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Monodominant woody species are frequent in the Pantanal. Monodominant forests of Erythrina fusca (Fabaceae) occur in Northern Pantanal, but little is known about the environmental factors that influence this dominance. This work investigated the relationship between flooding and soil characteristics and the E. fusca monodominance. We hypothesized that the dominance of E. fusca is mainly associated with extended flooding periods and lower soil fertility, factors frequently related to monodominance. We sampled 16 sites within the study area of 115 km2. We sampled three 50 × 5 m vegetation plots in each site, for species composition and abundance in multispecies forests and E. fusca monodominant forests. Soil samples were taken in each plot, and the duration of flooding was determined. We performed Canonical Correspondence Analysis and Regression Trees to verify the variation of species composition along environmental gradients and to identify which environmental factors influence this monodominance. We observed that flooding is the main factor driving E. fusca dominance, where higher flooding duration led to higher dominance. Further, the dominance of E. fusca is related to low soil fertility and higher concentration of sulfur and organic matter, than multispecies forests. Our findings confirm the hypothesis that dominance of E. fusca is associated with high flooding regimes with low soil fertility, which together act as a strong filter for other riparian forest species, thus favoring the dominance of E. fusca. [ABSTRACT FROM AUTHOR]

Agroforestry is a land-use system that combines arable and/or livestock management with tree cultivation, which has been shown to provide a wide range of socio-economic and ecological benefits. It is considered a promising strategy for enhancing resilience of agricultural systems that must remain productive despite increasing environmental and societal pressures. However, agroforestry systems pose a number of challenges for experimental research and scientific hypothesis testing because of their inherent spatiotemporal complexity. We reviewed current approaches to data analysis and sampling strategies of bio-physico-chemical indicators, including crop yield, in European temperate agroforestry systems to examine the existing statistical methods used in agroforestry experiments. We found multilevel models, which are commonly employed in ecology, to be underused and under-described in agroforestry system analysis. This Short Communication together with a companion R script are designed to act as an introduction to multilevel models and to promote their use in agroforestry research. [ABSTRACT FROM AUTHOR]

Land use is known to influence the diversity of vascular plants in the Miombo woodlands. However, little is known about the interaction between soil and land use in herbaceous and woody species. We compared the diversity of vascular plants at the plot level (20 m × 50 m) and site level for three sites in the Miombo woodlands of western Zambia subject to different levels of intensity classes of diffuse land use (e.g., livestock herbivory and selective timber harvesting). For each of the sites, twenty plots were randomly selected for assessment of species composition of vascular plant species, indicators of land-use intensity, and soil chemistry per plot. We hypothesized that the site with the lowest human impact would have the highest richness and diversity of woody and herbaceous species. At the site level, we found that richness and diversity of woody species were unaffected by land-use intensity, whereas herbaceous species richness was higher for the protected site (28 species on average per 1000 m2) than the two other sites (23 and 21 species on average per 1000 m2). At the plot level, herbaceous species richness was positively associated with woodcutting and soil pH. We interpret the positive effect of woodcutting on herbaceous species richness as the effect of lower competition by the woody component for resources such as water, nutrients, and light. With regard to the absence of any effect of land-use intensity on the richness of woody species, we conclude that in our study areas selective timber harvesting may be at a sustainable level and might even have a positive effect on the diversity of the herbaceous layer. [ABSTRACT FROM AUTHOR]

Psammotermes allocerus Silvestri, 1908 is the only described species representing the genus Psammotermes Desneux, 1902 in Southern Africa. The large geographical range of this subterranean termite covers both summer and winter rainfall regimes. Deadwood is the preferred food when available, but in more arid habitats, both live and dead grasses form the major dietary component. Along the Namib Desert margins, the species' localised herbivory creates circular bare patches known as fairy circles. For a regional phylogeographic study of this species, we sampled 65 sand termite populations within drier parts of Namibia, South Africa, and Angola. Based on combined molecular and ecological data, we found considerable genetic diversification within P. allocerus. Analyses of two mitochondrial markers (COI, COII), including a Bayesian inference tree, haplotype analysis and genetic distances suggest a delineation into seven highly differentiated genetic groups. The 'Succulent Karoo' group is additionally characterised by unique features of the royal chamber, nest and tunnel system. In conclusion, our data suggest that P. allocerus should be not regarded as one species but as a species complex. Termites of each analysed group 'Northern Namib', 'Western Kalahari Basin', 'Nama', 'Southwestern Kalahari', 'East Gariep', 'Southern Namib' and 'Succulent Karoo' should be considered as distinct species. The species name P. allocerus should be used for termites of the 'Succulent Karoo'. [ABSTRACT FROM AUTHOR]

Termite mounds contribute to the heterogeneity and productivity of many semi‐arid ecosystems worldwide. Regular spatial patterns of termite mounds are well documented but the underlying pattern‐building mechanisms remain to be clarified. This study analysed a comprehensive data set of Macrotermes michaelseni mound metrics, spatial patterns and dynamics, recorded 12 years apart within 1 km2 of Namibian thornbush savanna. We used both unmarked and marked point pattern analyses to assess spatial distributions of termite mounds. We recorded 485 termite mounds in 2007 and 2019. Out of the investigated 142 active termite mounds in 2007, 81 were active 12 years later. Only 2% (n = 3/129) of remnant mound sites in 2007 were newly colonised in 2019. All mounds were distributed at regular distances. Mounds higher than 2 m and long‐term active mounds (active in 2007 and 2019) showed high regularity. Mounds up to 0.7 m height and new mounds occurred in clusters and showed a spatial repulsion to large and long‐term active colonies. The spatial distribution of Boscia albitrunca trees generally clustered around termite mounds, but did not cluster around young colonies. The results contradict the hypothesis of preferred colony settlement on previously inhabited mound sites. Remnant mounds are relatively unlikely to be recolonised when recently abandoned. The observed spatial patterns show that intraspecific competition between large colonies is the decisive factor for regular spatial patterns of termite colonies, whereas small and young colonies are limited to unoccupied patches. Surrounding trees are a pattern‐building factor of only secondary importance. The spatio‐temporal scale in our study reveals general trends of termite mound life histories and spatial pattern‐building mechanisms. Availability of not previously inhabited sites form the patterns of founding new colonies. Well‐established mounds are highly regulated by intraspecific competition. This highlights that termites contribute to ecosystem heterogeneity through self‐organised spatial regularity. [ABSTRACT FROM AUTHOR]

Island biogeography provides concepts for conservation management as fragmented habitats are comparable to ocean islands. Remote sensing can help to extract terrestrial habitat islands on the landscape scale. However, little is known about the effects of image resolution and classification algorithms on resulting island size and related parameters. We study the combined effect of three image resolutions (2, 10, and 30 m) and three classification algorithms (Artificial Neural Network, Random Forest, Support Vector Machine) by extracting quartz islands from WorldView‐2 imagery using image segmentation. We compared four island parameters (i.e., area, distance, shape index, and perimeter–area ratio between resolutions and classifiers). We found that in all cases, image resolution and classification algorithms had a strong effect. However, image resolution was more important for area and shape. Artificial Neural Network always provided the best performance as a classifier (OA: 0.880, kappa: 0.801, F1: 0.912). Hence, conservation strategies could lead to different results when different pattern extraction strategies are applied. Future studies which aim at extracting terrestrial habitat islands from image datasets should aim for the highest possible resolution and compare the outcomes of different classifiers to ensure the best possible results. [ABSTRACT FROM AUTHOR]

Understanding the ecological requirements and thresholds of individual species is crucial to better predict potential outcomes of climate change on species distribution. In particular, species optima and lower and upper limits along resource gradients require attention. Based on Huisman‐Olff‐Fresco (HOF) models, we determined species‐specific responses along gradients of nine environmental parameters including depth in order to estimate niche attributes of 30 deep‐sea benthic amphipods occurring around Iceland. We, furthermore, examined the relationships between niche breadth, occupancy, and geographic range assuming that species with a wider niche are spatially more widely dispersed and vice versa. Overall, our results reveal that species react very differently to environmental gradients, which is independent of the family affiliation of the respective species. We could infer a strong relationship between occupancy and geographic range and also relate this to differences in niche breadth; that is specialist species with a narrow niche had a more limited distribution and may thus be more threatened by changing environmental conditions than generalist species, which are more widespread. Given the preponderance of rare species in the deep sea, this implies that many species could be at risk. However, this must be carefully weighed against geographical data gaps in this area, given that many deep‐sea areas are severely undersampled and the true distribution of most species is unknown. After all, our results underline that an accurate taxonomic classification is of crucial importance, without which ecological niche properties cannot be determined and which is hence fundamental for the assessment and understanding of changes in biodiversity in the face of increasing human perturbations. [ABSTRACT FROM AUTHOR]

We report the introduction of the central and eastern European helicid land snail Caucasotachea vindobonensis in North America. It was first recorded from Rensselaer County in the state of New York in 2015 by a community scientist. From 2016 to 2020, 14 additional occurrences in Rensselaer County, neighbouring Albany County and an imprecisely localized site in the Adirondack Mountains were recorded by community scientists. In 2020, the species was newly recorded at two sites in Schoharie County, NY, and at three sites in Québec, one of them approximately 700 km to the north of the initial record. Partial mitochondrial cox1 sequences from Rensselaer differ from an eastern Ukrainian haplotype only in a single substitution. Therefore, a Ukrainian origin for this introduction is likely, although not certain: the Rensselaer haplotype also differs in only two substitutions from a more widespread haplotype known from Ukraine, Hungary, Slovakia, Czechia, Serbia, and Bulgaria. An environmental niche model of the species based on occurrence data from central and eastern Europe indicated that a large region from the northern east coast to the midwestern United States is suitable for C. vindobonensis. The Canadian occurrences may indicate that the North American lineage is able to survive colder winters than predicted by the environmental niche model. Caucasotachea vindobonensis is not listed as a pest in Europe and it is unlikely to become an agricultural pest in North America as it prefers rotting plant material over living parts of plants, but its impact on native organisms can hardly be predicted. [ABSTRACT FROM AUTHOR]

The global struggle to conserve as many species as possible with limited resources requires an improvement of our knowledge on the distribution of biodiversity. In Iran, the state of knowledge is poor for most groups of organisms, except few vertebrate groups and vascular plants. Reptiles are one of the best known, most diverse vertebrate groups in Iran, with a high rate of endemism (ca. 29%), but distribution patterns and related environmental drivers remain poorly understood. In the present study, based on a large publicly available dataset, we use general additive modelling (GAM) to identify explanatory variables for species richness of reptiles in Iran. Results indicate heterogeneity parameters (range +entropy) as the variables with the highest explanatory values. Based on the grid cells of the predicted environmental richness, using hotspot analysis, we suggest seven hotspots of reptile diversity (HRDs) across the country. Our results corroborate the previously recognized HRDs and detect three additional ones, located alongside the major mountain ranges around the central deserts plateau, particularly in the Zagros Mountains. Four of the largest HRDs (ca. 90%) situate within the Irano‐Anatolian and Caucasus global biodiversity hotspot. In addition, our results reveal a large gap between identified HRDs and the current network of protected areas (PAs) in the country. While three of the detected HRDs in this study are partially touched (ca. 18%) by the PA network, overall, these areas are only covered by less than 10%. Therefore, the effectiveness of the current PAs for the protection of the reptile diversity of Iran is questionable. [ABSTRACT FROM AUTHOR]

1. Circular bare patches occur in high numbers among the vegetation of the Namib Desert margin. There is an ongoing scientific debate on the origin of these so‐called "fairy circles" (FCs). One of the most frequently discussed hypotheses regards the bare patches to be the result of localised herbivory by sand termites of the genus Psammotermes (family Rhinotermitidae). 2. In all earlier publications, the fairy circles of the Namib Desert region within their entire range from Angola through Namibia to South Africa were, in principle, regarded to be of one type, albeit increasing in size towards the north. Here we present evidence that at −16.23° latitude there is an abrupt discontinuity which separates the FCs on either side from each other. 3. South of this discontinuity all studied FCs share the properties of the previously described fairy circles in Namibia and South Africa, especially the presence of Psammotermes termites. 4. In contrast, north of −16.23°S the FCs are much larger and are caused by a different and undescribed termite species, most closely related to the harvester termite genus Microhodotermes (family Hodotermitidae). The two sets of fairy circles differ in a specific set of morphological features, associated termites, and soil parameters. 5. The observed juxtaposition of the newly discovered large structures caused by a hodotermitid termite and the Psammotermes FCs caused by a rhinotermitid species is interpreted as an interesting example of convergent evolution resulting in similar ecological structures. [ABSTRACT FROM AUTHOR]

While saltmarsh communities are endangered in many parts of the world due to anthropogenic impact, the risk of invasion by exotic plants is considered to be low because of their saline conditions. However, in urban areas, saltmarshes receive high nutrient freshwater input through stormwater discharge. We tested if invasion of saltmarsh by exotic plant species was facilitated by increased nutrients and reduced salinity associated with urban stormwater input. In a manipulative glasshouse experiment, we grew saltmarsh communities under four treatments: high salinity–low nutrients (control), high salinity–high nutrients, low salinity–low nutrients and low salinity–high nutrients. We then invaded the saltmarsh communities with four common invasive exotic plants. Their survival rates were monitored weekly for seven weeks before final harvesting. All exotic species showed significantly higher survival in the 'low salinity' treatment compared to the 'high salinity' treatment. There was variability among species, with three of four having low survival rates (0–3%) under 'high salinity' conditions, while survival of Protasparagus aethiopicus was reduced to only 53–59%. Our findings suggest that under natural conditions of saltmarshes, the establishment of exotic plant seedlings is restricted. Additional freshwater increased the survival of invading exotic species significantly, whereas adding nutrients increased biomass production but not necessarily survival of exotics. However, the results can be highly species dependant as shown by the unexpected salinity tolerance of P. aethiopicus. Reduction in salinity of saltmarsh due to stormwater input facilitates invasion by exotic plant species that would otherwise be unable to tolerate the highly saline environment. [ABSTRACT FROM AUTHOR]

The waters around Iceland, bounding the Northern North Atlantic and the Nordic seas, are a region characterized by complex hydrography and seabed topography. This and the presence of the Greenland-Iceland-Faroe-Scotland ridge (GIFR) are likely to have a major impact on the diversity and distribution of the benthic fauna there. Biodiversity in this region is also under increasing threat from climate-induced changes, ocean warming and acidification in particular, affecting the marine realm. The aim of the present study was to investigate the biodiversity and distributional patterns of amphipod crustaceans in Icelandic waters and how it relates to environmental variables and depth. A comprehensive data set from the literature and recent expeditions was compiled constituting distributional records for 355 amphipod species across a major depth gradient (18–3,700 m). Using a 1o hexagonal grid to map amphipod distributions and a set of environmental factors (depth, pH, phytobiomass, velocity, dissolved oxygen, dissolved iron, salinity and temperature) we could identify four distinct amphipod assemblages: A Deep-North, Deep-South, and a Coastal cluster as well as one restricted to the GIFR. In addition to depth, salinity and temperature were the main parameters that determined the distribution of amphipods. Diversity differed greatly between the depth clusters and was significantly higher in coastal and GIFR assemblages compared to the deep-sea clusters north and south of the GIFR. A variety of factors and processes are likely to be responsible for the perceived biodiversity patterns, which, however, appear to vary according to region and depth. Low diversity of amphipod communities in the Nordic basins can be interpreted as a reflection of the prevailing harsh environmental conditions in combination with a barrier effect of the GIFR. By contrast, low diversity of the deep North Atlantic assemblages might be linked to the variable nature of the oceanographic environment in the region over multiple spatio-temporal scales. Overall, our study highlights the importance of amphipods as a constituent part of Icelandic benthos. The strong responses of amphipod communities to certain water. mass variables raise the question of whether and how their distribution will change due to climate alteration, which should be a focus of future studies. [ABSTRACT FROM AUTHOR]

Questions: Habitat islands are often characterized by the presence of more or less sharp boundaries to adjacent matrix habitats. However, knowledge on boundaries of natural habitat islands is scarce, especially regarding patterns of beta diversity and its two underlying components: species turnover and nestedness. We therefore aim to quantify the effects of fine-scaled and sharp boundaries of quartz islands (quartz gravel-covered soils) on the different components of plant beta diversity and how they are linked to different soil environmental drivers. Location: Knersvlakte, Western Cape, South Africa. Methods: We sampled plant species richness in 56 fine-scale transects of 6 m × 1 m plots across eight different boundary types (four quartz island to matrix, four between habitats on quartz islands). Soil depth and chemistry (pH, electrical conductivity) were analyzed for each 1 m² plot. Differences in the two beta diversity components (turnover and nestedness) for each boundary type were tested by t tests. We used linear models to test relationships between species and environmental dissimilarity. Results: All boundary types showed high beta diversity. Species turnover was the prevailing component for six boundary types, the nestedness component was only important for two boundary types. We found a significant linear increase of species dissimilarity with increasing dissimilarity in soil pH and distinct plant communities for the habitat types, but no significant increase for electrical conductivity or soil depth. Conclusions: The spatial distinctiveness of the quartz islands leads to sharp boundaries, which result in high beta diversity, mainly through species turnover. This reflects the high levels of diversification and adaptation of the local plant communities. Nestedness occurred at two boundaries to the matrix, indicating that the latter does not necessarily represent an impermeable boundary for all species of the respective ecosystem. Studying diversity patterns across boundaries contributes to the question of applicability of island biogeography theory to habitat islands. [ABSTRACT FROM AUTHOR]

Questions: Inundation is an important feature linked to monodominance in tropical wetlands. The occurrence of neighbouring monodominant species indicates that soil can also have an important role. This study aimed to determine if variations in densities of three neighbouring monodominant species, Byrsonima cydoniifolia, Copernicia alba and Tabebuia aurea, are related primarily to variation of flooding patterns and secondarily to soil physicochemical variations in the Pantanal. Location: This study was performed in the southern Pantanal subregion of Miranda. Methods: We sampled 74 plots of 25 m × 25 m distributed among 15 patches of these species (five patches of each species). In each plot, we sampled all individuals of all shrub and tree species, checked the water mark left on tree trunks by the last flooding, and collected soil samples. Data were analyzed using canonical correspondence analysis (CCA) and regression trees. Results: We found that the main driver splitting these monodominant stands is soil, and that the secondary driver is inundation. The main drivers for Copernicia alba were higher soil pH, higher inundation and soil contents of Mg. For Byrsonima cydoniifolia, the main drivers were low Ca and Mg contents and high content of fine sand. Tabebuia aurea was the only species for which inundation was the main driver. Conclusions: We reject the hypothesis that inundation is the main driver splitting these monodominant stands. Differences in flooding levels were not crucial for two of the three species. Except for Tabebuia aurea, which was more influenced by inundation, soils were found to play an essential role in this spatial separation. [ABSTRACT FROM AUTHOR]

Aim: This study aimed to predict the alpha and beta plant diversity of an arid mountain based on environmental variables derived from remotely sensed and ground truth data. Location: Gebel Elba, Egypt. Methods: Based on 133 vegetation plots of 100 m2, we calculated alpha (Shannon index) and beta [the first ordination axis of nonmetric multidimensional scaling (NMDS1)] plant diversity. Generalized additive models (GAMs) were used to map alpha and beta diversity based on various environmental variables derived from a digital elevation model, the SoilGrids dataset, and very high resolution PlanetScope satellite imagery. The predictive models for alpha and beta diversity were mapped within the northern slopes of Gebel Elba. An ANOVA post hoc test was used to compare Shannon index and NMDS1 values among plant communities. Results: The selected models revealed the importance of altitude, landforms, solar insolation, catchment area, and modified soil‐adjusted vegetation index for Shannon diversity and NMDS1. The GAMs explained 54.9% of Shannon diversity and 80.6% of NMDS1. The predicted diversity maps showed that the mountainous area was more diverse and substantially different from the open desert. The post‐hoc test revealed a clear separation of mountain and desert vegetation. Conclusions: Employing remotely sensed variables combined with ground truth data offers great opportunities for exploring spatial patterns of biodiversity. By mapping alpha and beta diversity, it was possible to determine the spatial distribution of plant diversity in Gebel Elba; the results highlighted the importance of the wadi systems and higher slopes of this mountain area. We expect our findings can be generalized to similar arid mountains in the region.In this paper, we have created the first model‐based plant diversity maps for the arid mountain Gebel Elba. We found that topographical parameters and plant productivity played important roles in explaining predictive models of alpha and beta diversity on the northern slopes of this mountain. We expect that our findings can be generalized to similar arid mountains in the region. [ABSTRACT FROM AUTHOR]

Plant species that negatively affect their environment by encroachment require constant management and monitoring through field surveys. Drones have been suggested to support field surveyors allowing more accurate mapping with just-in-time aerial imagery. Furthermore, object-based image analysis tools could increase the accuracy of species maps. However, only few studies compare species distribution maps resulting from traditional field surveys and object-based image analysis using drone imagery. We acquired drone imagery for a saltmarsh area (18 ha) on the Hallig Nordstrandischmoor (Germany) with patches of Elymus athericus, a tall grass which encroaches higher parts of saltmarshes. A field survey was conducted afterwards using the drone orthoimagery as a baseline. We used object-based image analysis (OBIA) to segment CIR imagery into polygons which were classified into eight land cover classes. Finally, we compared polygons of the field-based and OBIA-based maps visually and for location, area, and overlap before and after post-processing. OBIA-based classification yielded good results (kappa = 0.937) and agreed in general with the field-based maps (field = 6.29 ha, drone = 6.22 ha with E. athericus dominance). Post-processing revealed 0.31 ha of misclassified polygons, which were often related to water runnels or shadows, leaving 5.91 ha of E. athericus cover. Overlap of both polygon maps was only 70% resulting from many small patches identified where E. athericus was absent. In sum, drones can greatly support field surveys in monitoring of plant species by allowing for accurate species maps and just-in-time captured very-high-resolution imagery. [ABSTRACT FROM AUTHOR]

Welwitschia mirabilis is one of the most extraordinary plant species on earth. With a fossil record of 112 My and phylogenetically isolated within the order Gnetales, the monotypic genus Welwitschia has survived only in the northern Namib Desert in Angola and Namibia. Despite its iconic role, the biogeography, ecological niche, and evolutionary history of the species remain poorly understood. Here we present the first comprehensive map of the strongly disjunct species range, and we explore the genetic relationships among all range fragments based on six SSR markers. We also assess the variation of the environmental niche and habitat preference. Our results confirm genetic divergence, which is consistent with the hypothetical existence of two subspecies within Welwitschia. We identify an efficient geographical barrier separating two gene pools at 18.7°S in northern Namibia. We also identify further diversification within each of the two subspecies, with several different gene pools in ten isolated range fragments. Given the presence of well-isolated populations with unique gene pools and the association with different bioclimatic variables, rock types, and habitats within arid river catchments, we can hypothesize that the present intraspecific diversity may have evolved at least in part within the present refuge of the northern Namib Desert. [ABSTRACT FROM AUTHOR]

Alien tree species have been introduced to Europe and often used as roadside trees. Currently, preference is given to species that are adapted to urban climate and drier conditions. Native epiphytic lichens are adapted to local tree species; however, little is known whether a shift toward more alien roadside trees would affect the diversity of epiphytic lichens within cities. We considered three genera of roadside trees that are common in Hamburg (Germany) Acer, Tilia , and Quercus , each with a native and an alien species per genus. Species numbers, frequency and diversity of epiphytic lichens were assessed and compared. Tree locations were grouped according to three classes of increasing traffic volume as a proxy for air pollution. Mean bark pH values have been recorded for each tree individual. The species pairs Quercus robur/rubra and Acer platanoides/saccharinum showed significant differences in the diversity and abundance of lichens, with the alien species showing lower values. The species pair Tilia cordata/tomentosa did not show any significant differences. The number of nitrogen-tolerant lichen species differed little among all tree species. Lichen species richness decreased with increasing traffic volume for all tree species pairs, thus demonstrating the inhibiting effect of traffic on the occurrence of lichens. Bark pH differed little between the species pairs yet high traffic volume resulted in an increased bark pH. In conclusion, two out of three alien species had negative effects on lichen diversity. Further tree species should be assessed to better estimate the effect of alien roadside trees on lichen diversity. [ABSTRACT FROM AUTHOR]

Questions: The arid Kalahari is prone to desertification as a result of climate change and/or land use. We analysed the effects of climatic variables and game herbivory on the vegetation composition to answer the question of how different life‐form types respond to climate, browsers and grazers as drivers of vegetation change. Location: The study was situated in the arid savanna of the South African Kalahari. Methods: Vegetation monitoring was conducted on 20 randomly selected permanent plots (100 m2) within a biodiversity observatory. For each plot, individuals per species (abundance) were counted annually and grouped into eight life‐form types (annual and perennial graminoid and annual and perennial forb, geophyte, dwarf shrub, large shrub and tree). We ran generalised linear mixed models (GLMM) with abundance per life‐form type as response variable and a seasonal drought index (Standardised Precipitation–Evapotranspiration Index [SPEI]), total annual rainfall, year, density of large game and springbok as fixed effects, plot as random effect and year as random slope. Results: Seasonal SPEI and density of large game and springbok had the strongest effect on abundance per life‐form type. Annual rainfall did not show any effect. The grazing large game had positive effects on the abundance of herbaceous life forms and dwarf shrubs. The predominantly browsing springbok had negative effects on perennial forbs, dwarf shrubs and trees. Directional trends in abundance per life form over time (increase of annual and decrease of perennial graminoids and forbs, increase of large shrubs) and decrease of total annual cover suggest early stages of vegetation degradation and shrub encroachment in response to both herbivory and climate. Conclusions: Our study showed that studies aimed at understanding the dynamics of arid systems should include both variance of intra‐annual climatic conditions and herbivore density as environmental drivers, related to abundance per life‐form/strategy type to reveal their specific responses to the environment. [ABSTRACT FROM AUTHOR]

1. Recently documented insect declines have caused major concerns and an increased interest in studies using long‐term population‐monitoring data. 2. Samples from a 12.2‐m suction trap were used to examine trends in phenology and abundance of Diptera over four decades. 3. The timing of peak flight has advanced by an average of 17 days, from 23 July in 1974 to 6 July in 2014. 4. The abundance of flies has decreased by 37% over the studied period (from April to September), and peak abundance has decreased by 48%. The flight period has started earlier in recent years, and in 2014, the number of flies was higher in spring until the 31st of May than in 1974. Possible causes and impacts of these changes are discussed. [ABSTRACT FROM AUTHOR]

Aim: Species–area relationships (SARs) are among the best investigated patterns in ecology, yet the shape of the function that should describe SARs and the biological meaning of the function parameters are disputed. Elevational gradients offer the opportunity of investigating how biodiversity responds to large variations in environmental characteristics within small geographical areas. We asked which function describes SARs at different elevations and explored how variations in environmental characteristics influence SAR shape. Location: Alborz Mountains (Iran). Taxon: Vascular plants. Methods: We used sets of nested plots (0.001 to 100 m2) placed at 100 m intervals from 2,000 to 4,500 m elevation to construct series of nested SARs as species accumulation curves. Then, we used these curves to assess the appropriateness of different SAR functions at different elevations. We investigated how parameters of the power function varied along the elevational gradient in response to variation in environmental parameters (ruggedness, temperature, precipitation, exposed rock, percentages of soil sand and total nitrogen, and productivity, expressed by the normalized difference vegetation index). Results: The most frequently observed best fit model was the power function, which is controlled by two parameters: z (the velocity in species accumulation with sampled area) and c (the species richness per unit area). z was positively influenced by temperature and soil nitrogen, decreasing with elevation. c was positively influenced by temperature and soil nitrogen, and negatively by rock cover, decreasing with elevation. Main conclusions: The decrease in c‐values with elevation is consistent with the altitudinal decrease in species richness and is explained by the increase in bare rock. By contrast, c was positively influenced by temperature and total nitrogen, which are two factors promoting plant growth. Similarly, z‐values decreased with elevation, thus indicating a decrease in beta diversity. [ABSTRACT FROM AUTHOR]

Background. In arid environments, plant primary productivity is generally low and highly variable both spatially and temporally. Resources are not evenly distributed in space and time (e.g., soil nutrients, water), and depend on global (El Niño/ Southern Oscillation) and local climate parameters. The launch of the Sentinel2-satellite, part of the European Copernicus program, has led to the provision of freely available data with a high spatial resolution (10 m per pixel). Here, we aimed to test whether Sentinel2-imagery can be used to quantify the spatial variability of a minor tussock grass (Enneapogon spp.) in an Australian arid area and whether we can identify different vegetation cover (e.g., grass from shrubs) along different temporal scenarios. Although short-lasting, the Enneapogon grassland has been identified as a key primary food source to animals in the arid environment. If we are able to identify and monitor the productivity of this species remotely, it will provide an important new tool for examining food resource dynamics and subsequent animal responses to them in arid habitat. Methods. We combined field vegetation surveys and Sentinel2-imagery to test if satellite spectral data can predict the spatial variability of Enneapogon over time, through GLMMs. Additionally, a cluster analysis (‘gower’ distance, ‘complete’ method), based on Enneapogon seed-productivity, and total vegetation cover in October 2016, identified three clusters: bare ground, grass dominated and shrub dominated. We compared the vegetation indices between these different clusters from October 2016 to January 2017. Results. We found that MSAVI2 and NDVI correlated with the proportion of Enneapogon with seeds across the landscape and this relationship changed over time. Both vegetation indices (MSAVI2 and NDVI) were higher in patches with high seed-productivity of Enneapogon than in bare soil, but only in October, a climatically-favorable period during which this dominant grass reached peak seed-productivity. Discussion. MSAVI2 and NDVI provided reliable estimates of the heterogeneity of vegetation type across the landscape only when measured in the Austral spring. This means that grass cover is related to seed-productivity and it is possible to remotely and reliably predict food resource availability in arid habitat, but only in certain conditions. The lack of significant differences between clusters in the summer was likely driven by the short-lasting nature of the vegetation in the study and the sparseness of the grass-dominated vegetation, in contrast to the shrub vegetation cluster that was particularly well measured by the NDVI. Conclusions. Overall, our study highlights the potential for Sentinel2-imagery to estimate and monitor the change in grass seed availability remotely in arid environments. However, heterogeneity in grassland cover is not as reliably measured as other types of vegetation and may only be well detected during periods of peak productivity (e.g., October 2016). [ABSTRACT FROM AUTHOR]

Aims: Gebel Elba is an arid mountain range supporting biological diversity that is incomparable to any other region of Egypt. This mountain has a vegetation structure and floristic community similar to the highlands of East Africa and the southwestern Arabian Peninsula. We aimed to provide the first classification of the vegetation units on Gebel Elba and identify the environmental factors controlling their distribution. Study area: Wadi Yahmib and its tributaries, which drain the north-western slopes of Gebel Elba, south-eastern Egypt. Methods: On the basis of 169 relevés, we used TWINSPAN to classify the perennial vegetation. We calculated separate GAMs for the deciduous and evergreen species to describe the patterns for each leaf strategy type with elevation. We used CCA to quantify the relationship between the perennial vegetation and the studied environmental factors. To estimate diversity and our sampling strategy, we used rarefaction curves for species richness. Results: We identified seven communities along the elevational gradient of Wadi Yahmib and its tributaries. We found that each community was restricted to a confined habitat depending on its drought resistance ability. Deciduous Vachellia woodland was the main vegetation type on Gebel Elba, while evergreen Olea woodland appeared in small fragments at higher elevations. We analysed the distribution patterns of deciduous and evergreen trees along the elevational gradient. We found a turnover at 500 m, indicating a potential ecotone between the Vachellia and Olea woodlands that was occupied by a Ficus community. CCA revealed the importance of altitude and soil quality in determining the vegetation structure of Gebel Elba. The species richness increased with elevation as a result of reduced stress and increased water availability at the upper wadis. Conclusions: This study identified seven vegetation units in the study area and showed the importance of orographic precipitation, soil quality and the complex topography in determining the habitats. [ABSTRACT FROM AUTHOR]

Satellite remote sensing has greatly facilitated the assessment of aboveground biomass in rangelands. Soil-adjusted vegetation indices have been developed to provide better predictions of aboveground biomass, especially for dryland regions. Semi-arid rangelands often complicate a remote sensing based assessment of aboveground biomass due to bright reflecting soils combined with sparse vegetation cover. We aim at evaluating whether soil-adjusted vegetation indices perform better than standard, i.e. unadjusted, vegetation indices in predicting dry aboveground biomass of a saline and semi-arid rangeland in NE-Iran. 672 biomass plots of 2 × 2 m were gathered and aggregated into 13 sites. Generalized Linear Regression Models (GLM) were compared for six different vegetation indices, three standard and three soil-adjusted vegetation indices. Vegetation indices were calculated from the MODIS MCD43A4 product. Model comparison was done using Akaike Information Criterion (AICc), Akaike weights and pseudo R2. Model fits for dry biomass showed that transformed NDVI and NDVI fitted best with R2 = 0.47 and R2 = 0.33, respectively. The optimized soil-adjusted vegetation index (OSAVI) behaved similar to NDVI but less precise. The soil-adjusted vegetation index (SAVI), the modified soil-adjusted vegetation index (MSAVI2) and the enhanced vegetation index (EVI) performed worse than a null model. Hence, soil-adjusted indices based on the soil-line concept performed worse than a simple square root transformation of the NDVI. However, more studies that compare MODIS based vegetation indices for rangeland biomass estimation are required to support our findings. We suggest applying a similar model comparison approach as performed in this study instead of relying on single vegetation indices in order to find optimal relationships with aboveground biomass estimation in rangelands. [ABSTRACT FROM AUTHOR]

Globally, the intensification of land use for agriculture, timber and fuel is considered the leading threat to the diversity and biomass of forests and woodlands. To suggest management options, it is important to understand the patterns and drivers of diversity, structure, biomass and carbon stock of woodland vegetation. In this study we used data from three sites in the Miombo woodlands of western Zambia, which are subject to low, medium and high land-use intensity. We sampled 20 plots of 1 000 m² at each of these sites. Woody vegetation was sampled for richness and structure to provide an understanding of the impact of land-use intensity. Woody plant species richness was not affected by land-use intensity. However, an ANOVA revealed that stem diameter at breast height (DBH) was higher at the low land-use intensity (national park) than at medium and high land-use intensities (selective timber harvest, and non-selective harvest for crop fields and timber). We tested three different allometric equations (one global and two regionally adapted) to determine woody aboveground biomass (AGB) and carbon stock at the three sites. The estimated AGB using the regionally adapted allometric equation of Ryan et al. and the global tropical equation of Brown et al. revealed that the AGB for low and high land-use intensity sites were significantly different from each other with the medium land-use intensity site being intermediate. We concluded that DBH and AGB estimations were influenced by the land-use intensity in the Miombo woodlands as suggested by other studies in the tropical forest and woodlands. [ABSTRACT FROM AUTHOR]

Copyright of African Journal of Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Climate and environmental heterogeneity are currently discussed as the most important drivers of plant diversity along altitudinal gradients. Compared to functional diversity, taxonomic diversity has received much more attention in research on altitudinal gradients, although functional diversity may provide more information on the ecological mechanisms shaping plant diversity. We assessed the importance of climatic and environmental heterogeneity as drivers of functional diversity in relation to altitude in the central Alborz Mountains, Iran. We sampled 132 vegetation plots along two altitudinal transects. Plant traits including life history, growth form, stem‐leaf ratio, spinescence, hairiness, leaf consistency, dispersal type and plant height were recorded. Functional diversity was measured as functional richness, Rao's quadratic entropy, and their standardized effect sizes (SESs). In general, functional diversity decreased with altitude. The decrease in observed functional diversity was related to the decrease in taxonomic richness. SESs of functional diversity showed contrasting trends, depending on transect and index. At both transects, climatic stress best explained the variation in observed and expected functional diversity. Harsh climatic conditions at higher altitudes decreased the number of species and thus the functional trait space. Environmental heterogeneity played only a minor role for shaping functional diversity. We expect this effect to be due to the length of the sampled altitudinal transects. With increasing length, small‐scale drivers become less effective. The two transects favoured different environmental drivers, meaning that transferability of single studies could be difficult. [ABSTRACT FROM AUTHOR]

An important indicator of the rangeland health, associated with land degradation, is the ability of semi-natural rangelands to provide forage of sufficient quality for livestock production. In Qilian Mountains (Gansu Province, NW China) biomass production and forage quality are dependent on the seasonality of precipitation and temperature; most of the precipitation falls during summer season, when sheep, goats and yaks graze mountain rangelands. To sustain the rangelands and to improve the management strategies, the assessment of the forage quality should be implemented. The purpose of this research was to study the response of biomass, forage quality and macronutrient content different levels of grazing intensity in Qilian rangelands. We sampled aboveground biomass in the growing seasons in 2012 and 2013 within spring/autumn or summer grazing regimes in two altitudinal zones below and above 3000 m a.s.l. (montane-subalpine and subalpine-alpine respectively). In order to estimate forage quality, biomass was sampled in 1 m × 1 m plots, assigned to the center of 10 ×10 m sites, from which we collected different indicator parameters of rangeland health. Mineral and fiber content of forage biomass was estimated under different levels of grazing intensity with regard to the growing period. It was found that an increase in grazing intensity led to a decrease in dry matter weight. No linearity was observed in the relationship between nutritive value and grazing intensity. The highest fiber content (59.20 %) was found in plots mostly disturbed by grazing. The highest protein (16.30 %) and the lowest fiber (51.30 %) contents were associated with slightly grazing intensity. Concentrations of the mineral elements, such as Zn, P, K and S varied significantly and showed maximum values under low grazing intensity. [ABSTRACT FROM AUTHOR]

The Succulent Karoo biome is a renowned centre of biodiversity and endemism in the arid winter rainfall region of South Africa that is threatened by climate change. On 20 permanently marked plots within a biodiversity observatory, species richness and cover were assessed annually from 2002 to 2017 during the growing season. We were interested, firstly, in whether the vegetation showed any trends in response to the strong decrease in grazing pressure, which occurred at the beginning of the monitoring period, and secondly, in the effect of seasonal climate on the vegetation. We analysed the responses of species richness and cover in four life forms to seasonal rainfall and the standardised precipitation-evapotranspiration index (SPEI) using linear mixed-effect models. Time had a positive effect on richness of annual species and a negative effect on cover of shrubs and annuals, which increased in response to SPEI and less strongly to rainfall during autumn and winter. Habitat did not have any effect and geophytes and perennial herbs did not show any significant response. The importance of SPEI during autumn and winter is discussed in relation to potential germination cues and the projected decrease in rainfall and increase in temperature during these seasons. [ABSTRACT FROM AUTHOR]

Abstract: Aim: The impact of invasive species may depend on dissimilarity of their functional traits relative to the native community. Therefore, comparing species traits in a multidimensional space can help to better understand invader impacts, but novel methods are needed to effectively measure multiple traits across diverse plant communities. The main aim was to assess biochemical leaf parameters based on field spectra in a whole‐community approach. Our specific objectives were to assess (1) biochemical differentiation within the plant community, (2) accuracy of spectroscopic prediction models of biochemical parameters, and (3) ability to depict the multivariate differentiation using field spectroscopy. Location: Mediterranean dune ecosystems, Atlantic coast, southwest Portugal. Methods: We analysed leaf biomass of 18 species, including two invasive acacias, for C, δ13C, N, δ15N, lignin, fibre and tannin. Additionally, we collected leaf and canopy field spectra of each sampled plant. We used partial least squares (PLS) regression to predict biochemical parameters from field spectra. Further, we assessed the biochemical differentiation of the species using PCA based on wet chemically determined as well as spectroscopically predicted values. Results: We found high biochemical variation among species and, in particular, marked trait dissimilarity between invasive Acacia spp. and native species, primarily with respect to N content. Biochemical parameters were predicted successfully based on field spectra. Prediction accuracies were particularly high with C, δ13C, N and tannin. A PCA of biochemical parameters showed that invasive Acacia spp. were distinct from native species of the same life form, but grouped with native dwarf shrubs. This pattern was accurately reproduced by a PCA using spectroscopically predicted values. Conclusions: Invasive Acacia spp. have different leaf traits compared to native species of similar growth form. Their trait dissimilarity likely exacerbates their impacts on the ecosystem. This trait dissimilarity in leaf biochemistry can be accurately predicted with hyperspectral whole‐community models. Thus, field spectroscopy can substantially increase the spatial and temporal resolution of measurements and hence facilitate assessments of ecosystem functioning and invader impacts at ecosystem scale. [ABSTRACT FROM AUTHOR]

Seedling establishment is a crucial factor for spatial dynamics of treelines. However, safe sites for successful tree regeneration which is a basic prerequisite for a supposed treeline advance in response to climate warming have not been fully characterised, especially in the Himalayas. In this study, we aim at analysing safe sites of the tree species Abies spectabilis, Betula utilis and Rhododendron campanulatum, dominating the near-natural treeline ecotone in Rolwaling Himal, Nepal. We investigated microhabitat ground cover of established seedlings in rectangular plots along the treeline ecotone from subalpine forest stands via the krummholz belt to alpine dwarf shrub heaths (3800-4200 m). We examined protective elements that potentially ameliorate seedlings' growth conditions and quantified the distance of seedlings to the nearest protective element. Our results showed species-specific microhabitat preferences for seedling establishment. While A. spectabilis seedlings establish on ground that is covered in average by 70% with litter, B. utilis and R. campanulatum seedlings primarily emerge on bryophyte mats (mean site cover 80%). Microhabitat structure did not vary significantly in relation to different vegetation types encompassing the treeline ecotone. The majority of seedlings of all species grew in maximum 2 m distance to at least one potentially protective element. Geomorphic elements and deadwood were the most important shelters for seedling establishment. Our results emphasise the importance of safe sites for successful tree regeneration in harsh environments. As growth conditions in high mountain ecosystems may substantially alter under contemporary climate change, the necessity of safe sites may increase to buffer potential extremes. [ABSTRACT FROM AUTHOR]

Aim: The social-ecological systems of south east Angola currently undergo rapid transformations and at the same time the region is highly understudied. We aim to provide a first comprehensive analysis of vegetation types, their environmental drivers and woody species diversity of the region. Study area: Cubango River Basin in south-east Angola and northern Namibia. Methods: We conducted a plot-based vegetation survey covering all major terrestrial vegetation types. 190 relevés of 1000 m2 were classified based on a numerical classification approach. We used NMDS ordination and data on soils from field sampling, topography, climate and remotely sensed land surface phenology to investigate vegetation-environment relationships. The number of woody species was estimated using four non-parametric species richness estimators and rarefaction curves. Results: We provided a detailed description of the resulting twelve woody plant communities, in terms of species composition, structure, and habitat characteristics. At the scale of the Cubango Basin, differences in the regional climate were the most important drivers of plant species composition. Topsoil properties did not vary much throughout the study area, but higher contents of silt and clay in the lower soil horizons appeared to drive species composition in the miombo woodlands. Furthermore, we demonstrated how the usage of land surface phenology metrics add value to the interpretation of ecological properties of plant communities in providing insights on the timing of the growing season and on different aspects of above-ground biomass. The number of woody species in the entire Cubango Basin was estimated to be 471 (SD=29) species, for the miombo woodlands 302 (SD=11) species, and for the Baikiaea woodlands 262 (SD=20) species. Conclusion: The presented classification scheme and the analysis of environmental drivers of vegetation types provide a solid basis for future investigations of the vegetation of southeast Angola, and will provide important baseline data for conservation planning and sustainable natural resource management. [ABSTRACT FROM AUTHOR]

Mountains are an excellent system for evaluating ecological and biogeographical patterns. The obvious variations of the environmental factors along the altitude create different zones with adapted plant assemblages. However, few studies make use of plant functional type (PFT) for describing the variation of vegetation along altitudinal gradients. A PFT is a group of taxa with similar traits which respond similarly to the environmental gradients. In this study, we used PFTs as indicators describing five vegetation zones in the western Alborz Mt, Iran from 2000 - 4500 m. The plant trait data presented here covers six plant traits including growth form, stemleaf ratio, spinescence, hairiness, leaf consistency and plant height of 297 species. We considered altitude and soil factors to test the importance of environmental variables. We applied a multivariate analysis of three table ordination, i.e. environmental, species, and traits data to identify the PFTs. We further applied fourth-corner statistic to quantify trait-environment relationships. A constrained hierarchical clustering was used to detect five altitudinal zones and two zones of low and high nitrogen concentration. With regard to altitude we discuss the distribution of species, traits and PFTs. Growth form, plant height and stem-leaf ratio were significantly related to altitude and nitrogen. We identified 19 PFTs from which 18 were significantly associated to one or more altitudinal zones. While the lower altitudinal zones contain a variety of PFTs higher altitudes contain less PFTs with the highest altitude containing only one single PFT, tiny rosette plants with soft mesomorphic leaves. We identified grazing and climatic harshness as well as rockiness as the most important drivers of the distribution of plant functional traits and types across the studied gradient. [ABSTRACT FROM AUTHOR]

Copyright of African Journal of Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Questions: Species composition and ecology of treeline vegetation types in the Rolwaling Valley is largely unknown to date. The aim of this study is to differentiate plant communities along the elevational gradient in the treeline ecotone, and to identify site factors which cause the differentiation of the treeline ecotone vegetation. Study area: Rolwaling Valley (27°52' N; 86°25' E) in the central Himalaya, Nepal. Methods: We included 91 phytosociological relevés along three elevational transects in this analysis, ranging from 3745 to 4300 m a.s.l. Plant communities were differentiated and vegetation-environment relationships analysed using cluster analysis and ordination. For each community and higher ranked unit, we detected diagnostic species according to their fidelity index (phi coefficient). Ecological preferences of each community were examined using one-way analysis of variance (ANOVA). Results and conclusions: We identified five communities, belonging to two different classes: the Synotis alata-Abies spectabilis and Ribes glaciale-Abies spectabilis communities occupy the upper part of the subalpine forest zone, representing the uppermost forest stands below treeline. These communities are primarily comprised of Abies spectabilis and Betula utilis in the tree layer, with varying cover of several tree species and distinct differences within the herb layer. Above treeline, the mixed forest stands are replaced by the species-poor Boschniakia himalaica-Rhododendron campanulatum community, forming a dense krummholz belt. We assigned the forest and krummholz communities to the class Betula utilis-Abies spectabilis forests. In the alpine zone two communities were classified and assigned to the class Dasiphora arbuscula-Rhododendron anthopogon dwarf shrub heaths.The species-poor Pedicularis cf. microcalyx-Rhododendron anthopogon community has a less developed herbaceous layer, whereas the Anaphalis royleana-Rhododendron anthopogon community is characterized by higher cover and higher species richness of herbs and grasses. Species composition of identified communities is mainly differentiated by soil temperature, nitrogen supply and availability, and soil moisture content. [ABSTRACT FROM AUTHOR]

Climate warming is expected to advance treelines to higher elevations. However, empirical studies in diverse mountain ranges give evidence of both advancing alpine treelines as well as rather insignificant responses. In this context, we aim at investigating the sensitivity and responsiveness of the near-natural treeline ecotone in Rolwaling Himal, Nepal, to climate warming. We analysed population densities of tree species along the treeline ecotone from closed forest stands via the krummholz belt to alpine dwarf shrub heaths (3700-4200 m) at 50 plots in 2013 and 2014. We quantified species - environment relationships, i.e. the change of environmental conditions (e.g., nutrient and thermal deficits, plant interactions) across the ecotone by means of redundancy analyses, variation partitioning and distance-based Moran's eigenvector maps. In particular, we focus on explaining the high competitiveness of Rhododendron campanulatum forming a dense krummholz belt and on the implications for the responsiveness of Himalayan krummholz treelines to climate change. Results indicate that treeline trees in the ecotone show species-specific responses to the influence of environmental parameters, and that juvenile and adult tree responses are modulated by environmental constraints in differing intensity. Moreover, the species - environment relationships suggest that the investigated krummholz belt will largely prevent the upward migration of other tree species and thus constrain the future response of Himalayan krummholz treelines to climate warming. [ABSTRACT FROM AUTHOR]

Environmental heterogeneity and plant-plant interactions are key factors shaping plant communities. However, the spatial dimension of plant-plant interactions has seldom been addressed in field studies. This is at least partially rooted in a lack of methods that can accurately resolve functional processes in a spatially explicit manner. Isoscapes, that is, spatially explicit representations of stable isotope data, provide a versatile means to trace functional changes on spatial scales, for example, related to N-cycling (foliar δ15N) and water use efficiency (WUEi, foliar δ13C). In a case study in a nutrient-depleted Mediterranean dune ecosystem, we analysed the spatial impact of the invasive N2-fixing Acacia longifolia on three native species of different functional types using δ15N and δ13C isoscapes and spatial autocorrelation analyses. Isoscapes revealed strong spatial patterns in δ15N and δ13C with pronounced species-specific differences, demonstrating distinct spatial ranges of plant-plant interactions. A coniferous tree and an ericaceous dwarf shrub showed significant enrichment in δ15N within a range of 5-8 m surrounding the canopy of A. longifolia, indicating input of N originating from symbiotic N2-fixation by the invader. In the dwarf shrub, which was most responsive to invader influence, enrichment in δ13C additionally demonstrated spatially explicit changes to WUEi, while a native N2-fixer was unresponsive to the presence of the invader. Furthermore, δ15N and δ13C isoscapes yielded different patterns, indicating that plant-plant interactions can have distinct spatial distributions and ranges based on the process measured. Additionally, the magnitude of the effect differed between field situations with high and low invasion pressure. This study highlights that the spatial scale must be accounted for when assessing the effects and outcome of species interactions. Functional tracers such as stable isotopes enable us to quantify spatial ranges of plant-plant interactions, providing empirical data that can help to better understand and predict complex species interactions in multifaceted natural environments. [ABSTRACT FROM AUTHOR]

Understanding interactions between native and invasive plant species in field settings and quantifying the impact of invaders in heterogeneous native ecosystems requires resolving the spatial scale on which these processes take place. Therefore, functional tracers are needed that enable resolving the alterations induced by exotic plant invasion in contrast to natural variation in a spatially explicit way. 15N isoscapes, i.e., spatially referenced representations of stable nitrogen isotopic signatures, have recently provided such a tracer. However, different processes, e.g. water, nitrogen or carbon cycles, may be affected at different spatial scales. Thus multi-isotope studies, by using different functional tracers, can potentially return a more integrated picture of invader impact. This is particularly true when isoscapes are submitted to statistical methods suitable to find homogeneous subgroups in multivariate data such as cluster analysis. Here, we used model-based clustering of spatially explicit foliar δ15N and δ13C isoscapes together with N concentration of a native indicator species, Corema album, to map regions of influence in a Portuguese dune ecosystem invaded by the N2-fixing Acacia longifolia. Cluster analysis identified regions with pronounced alterations in N budget and water use efficiency in the native species, with a more than twofold increase in foliar N, and δ13C and δ15N enrichment of up to 2‰ and 8‰ closer to the invader, respectively. Furthermore, clusters of multiple functional tracers indicated a spatial shift from facilitation through N addition in the proximity of the invader to competition for resources other than N in close contact. Finding homogeneous subgroups in multi-isotope data by means of model-based cluster analysis provided an effective tool for detecting spatial structure in processes affecting plant physiology and performance. The proposed method can give an objective measure of the spatial extent of influence of plant-plant interactions, thus improving our understanding of spatial pattern and interactions in plant communities. [ABSTRACT FROM AUTHOR]

Inundation and fire can affect the structure of riparian vegetation in wetlands. Our aim was to verify if there are differences in richness, abundance, basal area, composition and topographic preference of woody species in riparian forests related to the fire history, flooding duration, or the interaction between both. The study was conducted in the riparian forests of the Paraguay River some of which were burned three times between 2001 and 2011. We sampled trees with a girth of at least 5 cm at breast height in 150 5 × 10 m plots (79 burned and 71 unburned). We also measured height of the flood mark and estimated the flooding duration of each plot. We performed Generalized Linear Mixed Models to verify differences in richness, basal area, and abundance of individuals associated to interaction of fire and inundation. We used an analysis of similarity (ANOSIM) and indicator species analysis to identify differences in composition of species and the association with burned and unburned area according to different levels of inundation. Finally, we used a hierarchical set of Generalized Linear Models (GLM), the so-called HOF models, to analyse each species’ specific response to inundation based on topography and to determine their preferred optimal topographic position for both burned as well as unburned areas. Richness was positively associated with elevation only in burned areas while abundance was negatively influenced by inundation only in burned areas. Basal area was negatively associated with time of inundation independent of fire history. There were 15 species which were significant indicators for at least one combination of the studied factors. We found nine species in burned areas and 15 in unburned areas, with response curves in HOF models along the inundation gradient. From these, five species shifted their optimal position along the inundation gradient in burned areas. The interaction of fire and inundation did not appear to affect the basal area, but it did affect the richness, number of individuals, success of some species, and seemed to shape the boundary of these forests as shown by the difference in the positioning of these species along the inundation gradient. [ABSTRACT FROM AUTHOR]

In many parts of Africa, spatially-explicit information on plant α-diversity, i.e., the number of species in a given area, is missing as baseline information for spatial planning. We present an approach on how to combine vegetation-plot databases and remotely-sensed land surface phenology (LSP) metrics to predict plant α-diversity on a regional scale. We gathered data on plant α-diversity, measured as species density, from 999 vegetation plots sized 20 m × 50 m covering all major vegetation units of the Okavango basin in the countries of Angola, Namibia and Botswana. As predictor variables, we used MODIS LSP metrics averaged over 12 years (250-m spatial resolution) and three topographic attributes calculated from the SRTM digital elevation model. Furthermore, we tested whether additional climatic data could improve predictions. We tested three predictor subsets: (1) remote sensing variables; (2) climatic variables; and (3) all variables combined. We used two statistical modeling approaches, random forests and boosted regression trees, to predict vascular plant α-diversity. The resulting maps showed that the Miombo woodlands of the Angolan Central Plateau featured the highest diversity, and the lowest values were predicted for the thornbush savanna in the Okavango Delta area. Models built on the entire dataset exhibited the best performance followed by climate-only models and remote sensing-only models. However, models including climate data showed artifacts. In spite of lower model performance, models based only on LSP metrics produced the most realistic maps. Furthermore, they revealed local differences in plant diversity of the landscape mosaic that were blurred by homogenous belts as predicted by climate-based models. This study pinpoints the high potential of LSP metrics used in conjunction with biodiversity data derived from vegetation-plot databases to produce spatial information on a regional scale that is urgently needed for basic natural resource management applications. [ABSTRACT FROM AUTHOR]

In this article, the author discusses biological nature of the fairy circle (FC), role of sand termite in FC and interaction of desert grasses in sand ecosystem. The author highlights plant growth, water consumption and forming soil water in vegetations growth location. The author mentions hypothesis regarding vegetation.

Epidermal structures (ES) of leaves are known to affect the functional properties and spectral responses. Spectral studies focused mostly on the effect of hairs or wax layers only. We studied a wider range of different ES and their impact on spectral properties. Additionally, we identified spectral regions that allow distinguishing different ES. We used a field spectrometer to measure ex situ leaf spectral responses from 350 nm-2500 nm. A spectral library for 25 species of the succulent family Aizoaceae was assembled. Five functional types were defined based on ES: flat epidermal cell surface, convex to papillary epidermal cell surface, bladder cells, hairs and wax cover. We tested the separability of ES using partial least squares discriminant analysis (PLS-DA) based on the spectral data. Subsequently, variable importance (VIP) was calculated to identify spectral regions relevant for discriminating our functional types (classes). Classification performance was high, with a kappa value of 0.9 indicating well-separable spectral classes. VIP calculations identified six spectral regions of increased importance for the classification. We confirmed and extended previous findings regarding the visible-near-infrared spectral region. Our experiments also confirmed that epidermal leaf traits can be classified due to clearly distinguishable spectral signatures across species and genera within the Aizoaceae. [ABSTRACT FROM AUTHOR]

Background: Wild plants are used as food for human populations where people still depend on natural resources to survive. This study aimed at identifying wild plants and edible uses known in four rural communities of the Pantanal-Brazil, estimating the use value and understanding how distance to the urban areas, gender, age and number of different environments available in the vicinity can influence the knowledge and use of these plants by local people. Methods: Data on edible plants with known uses by communities were obtained through semi-structured interviews. A form with standardized information was used for all communities in order to obtain comparable data for analysis. For the quantitative analysis of the factors that could influence the number of species known by the population, a generalized linear model (GLM) was conducted using a negative binomial distribution as the data consisted of counts (number of citations). Results: A total of 54 wild species were identified with food uses, included in 44 genera and 30 families of angiosperms. Besides food use, the species are also known as medicine, bait, construction, technology and other. The species with the highest use value was Acrocomia aculeata. Older people, aged more than 60 years, and those living in more remote communities farther from cities know more wild edible plants. Statistical analysis showed no difference regarding gender or number of vegetation types available in the vicinity and the number of plants known by locals. Conclusion: This study indicated more knowledge retained in communities more distant from the urban area, indifference in distribution of knowledge between genders and the higher cultural competence of elderly people in respect to knowledge of wild edible botanicals. [ABSTRACT FROM AUTHOR]

Linking remote sensing methodology to stable isotope ecology provides a promising approach to study ecological processes from small to large spatial scales. Here, we show that δ15N can be detected in fresh leaf reflectance spectra of field samples along a spatial gradient of increasing nitrogen input from an N2-fixing invasive species. However, in field data it is unclear whether δ15N directly influences leaf reflectance spectra or if the relationship is based on covariation between δ15N and foliar nitrogen content or other leaf properties. Using a 15N-labeling approach, we experimentally varied δ15N independently of any other leaf properties in three plant species across different leaf developmental and physiological states. δ15N could successfully be modeled by means of partial least squares (PLSs) regressions, using leaf reflectance spectra as predictor variables. PLS models explained 53–73% of the variation in δ15N within species. Several wavelength regions important for predicting δ15N were consistent across species and could furthermore be related to known absorption features of N-containing molecular bonds. By eliminating covariation with other leaf properties as an explanation for the relationship between reflectance and δ15N, our results demonstrate that 15N itself has an inherent effect on leaf reflectance spectra. Thus, our study substantiates the use of spectroscopic measurements to retrieve isotopic signatures for ecological studies and encourages future development. Furthermore, our results highlight the great potential of optical measurements for up-scaling isotope ecology to larger spatial scales. [ABSTRACT FROM AUTHOR]

The invasive shrub, Acacia longifolia, native to southeastern Australia, has a negative impact on vegetation and ecosystem functioning in Portuguese dune ecosystems. In order to spectrally discriminate A. longifolia from other non-native and native species, we developed a classification model based on leaf reflectance spectra (350-2500 nm) and condensed leaf tannin content. High variation of leaf tannin content is common for Mediterranean shrub and tree species, in particular between N-fixing and non-N-fixing species, as well as within the genus, Acacia. However, variation in leaf tannin content has not been studied in coastal dune ecosystems in southwest Portugal. We hypothesized that condensed tannin concentration varies significantly across species, further allowing for distinguishing invasive, nitrogen-fixing A. longifolia from other vegetation based on leaf spectral reflectance data. Spectral field measurements were carried out using an ASD FieldSpec FR spectroradiometer attached to an ASD leaf clip in order to collect 750 in situ leaf reflectance spectra of seven frequent plant species at three study sites in southwest Portugal. We applied partial least squares (PLS) regression to predict the obtained leaf reflectance spectra of A. longifolia individuals to their corresponding tannin concentration. A. longifolia had the lowest tannin concentration of all investigated species. Four wavelength regions (675-710 nm, 1060-1170 nm, 1360-1450 nm and 1630-1740 nm) were identified as being highly correlated with tannin concentration. A spectra-based classification model of the different plant species was calculated using a principal component analysis-linear discriminant analysis (PCA-LDA). The best prediction of A. longifolia was achieved by using wavelength regions between 1360-1450 nm and 1630-1740 nm, resulting in a user's accuracy of 98.9%. In comparison, selecting the entire wavelength range, the best user accuracy only reached 86.5% for A. longifolia individuals. [ABSTRACT FROM AUTHOR]

The phylogeographic structure of the land snail Xerocrassa mesostena on Crete inferred from AFLP markers and mitochondrial cox1 sequences can be explained by three mechanisms: gene flow restriction, population expansion and leptokurtic dispersal. Gene flow restriction by geographic barriers caused subdivision of the gene pool into distinct clusters. Population expansion was probably facilitated by deforestation of Crete in the postglacial. Newly available areas were colonized by leptokurtic dispersal, i.e. slow active expansion resulting in isolation by distance within the clusters and occasional long distance dispersal events that resulted in departures from the isolation by distance model. Less than one percent of the AFLP markers show correlations with environmental variables. Random phylogeographic breaks in the distribution of the mitochondrial haplotype groups indicate that single locus markers, especially mitochondrial DNA, might result in a misleading picture of the phylogeographic structure of a species. Restriction of gene flow between metapopulations caused by geographical barriers can interact with sexual selection resulting in the differentiation of these metapopulations into separate species without noticeable ecological differentiation. Evidence for gene flow between parapatrically distributed evolutionary units representing different stages of the speciation process suggests that the ongoing process of fragmentation of the X. mesostena complex might be an example for parapatric speciation. The lack of ecological differentiation between these units confirms theoretical predictions that divergent selection for local adaptation is not required for rapid speciation. [ABSTRACT FROM AUTHOR]

Databases on plant traits as well as the availability of global coverage of high spatial and spectral resolution remote-sensing data are constantly growing. However, little effort has been made to analyse the relationship between plant traits and remote-sensing data while simultaneously taking species identity and abundance into consideration. We correlated quantitative and qualitative plant traits from a dwarf shrub savanna in Namibia, with spectral indices derived from two hyperspectral sensors, HyMap and the Compact High Resolution Imaging Spectrometer Project for On-Board Autonomy (CHRIS-PROBA), which differ in their spatial and spectral resolution. We used RLQ analysis and the fourth-corner statistic, which are two three-table ordination approaches that circumvent the so-called fourth-corner problem. A higher spatial resolution helped to identify trait–index correlations linked to vegetation structure, while a lower spatial resolution pointed at traits linked to vegetation cover. A higher spectral resolution did not improve the relationships between spectral indices and plant traits. However, continuous hyperspectral signatures allowed for the calculation of spectral indices that make use of the detailed spectra allowing for more sophisticated spectral indices. We propose RLQ and the fourth-corner statistic as suitable tools for the remote sensing and Earth observation community that allow the direct correlation of trait databases with remotely sensed information. [ABSTRACT FROM AUTHOR]

Local people's perceptions of plant species are an important source of information on species distribution and rarity, as well as long-term vegetation change. This study involves an ethnobotanical survey and the identification of potential factors that explain differences in the perceptions and valuation of woody plant species in three ethnic groups (Fulani, Mossi and Samo) of the sub-Sahel of Burkina Faso. Some 87 groups of informants from 20 villages were interviewed for this study. A species list of woody plants and their estimated abundance was categorized in terms of their uses: food, medicine, fodder, construction, energy and handicrafts. In addition, the most important species, and those considered a priority for conservation, were identified. A total of 90 woody species were mentioned in the six categories. They were from 64 genera and 32 families and sub-families, of which the Caesalpinioideae, Combretaceae, Mimosoideae and the Capparaceae dominated. In all three ethnic groups, more than 80 % of the reported species were used for energy, 60 % for medicine and 40-50 % for food. Gender was not a determinant of plant use. However, age was found to have an impact on plant knowledge in all three ethnic groups, with older people (over 50 years) reporting significantly more species than younger people (25-50 years): ( U = 425, df: 15, 14, z = −4.42, p < 0.05). There was a significant difference in plant use among the three ethnic groups (ANOSIM; R = 0.64, p < 0.001), and this could be explained by differences in culture and local environmental conditions controlling species distribution and availability. Balanites aegyptiaca was the most used species by all three ethnic groups. The most important species and identified conservation priorities, from the informants' perspective, were similar for all ethnic groups and were mainly food species with a high socioeconomic value: Vitellaria paradoxa, Adansonia digitata, Tamarindus indica, Parkia biglobosa, Lannea microcarpa and Ziziphus mauritiana. Development projects should incorporate the preferences of local people for certain species as part of the overall strategy for poverty alleviation in Burkina Faso. [ABSTRACT FROM AUTHOR]

Transhumant pastoralism is an important activity in southern Morocco. Migration pattern of transhumant pastoralists can be affected by physical factors (e.g. droughts and diseases) or socioeconomic factors (e.g. schooling options for children and migration costs). We studied the spatio-temporal rangeland usage of the three tribes Ait Mgoun, Ait Zekri, and Ait Toumert in the south-central Atlas region with a two-fold approach. First, we tracked the migration movements of one representative transhumant herd using the Advanced Research and Global Observation Satellite (ARGOS) collars, which record coordinates from satellite signals. Second, we interviewed herders to obtain information about general grazing practices of the respective tribe and to gain more direct information on motivations underlying decisions. For each tribe we observed small-, medium- and large-scale movements. We found that the most important drivers of migration decisions were seasonal fodder availability and weather conditions in combination with herd-specific risk and cost assessment, as well as personal factors. In conclusion, general migration patterns vary in time, both between and within the tribes, but according to a regulatory framework. Moreover, it appears that both the customary rules and its flexible adaptation to physical constraints are generally beneficial in terms of conservation of the arid and semiarid rangeland resources. [ABSTRACT FROM AUTHOR]

Questions Which plant traits consistently respond to grazing in different years and across habitat-related environmental heterogeneity? Does the proposed partial RLQ approach allow partitioning of grazing-related environmental parameters from other environmental and temporal variations? Location Semi-arid savannas of central Namibia. Methods We recorded nine quantitative and 12 categorical traits from 87 plant species along grazing gradients in semi-arid Namibian rangelands. We sampled from gradients in different habitat settings in 2 yr with differing total rainfall amounts. We first examined trait-environment relations with RLQ analysis. To remove confounding effects of temporal and habitat-related environmental variation on trait performance, we introduced a novel partial RLQ analysis approach. Furthermore, we used the fourth-corner statistic to quantify and test relations between traits, environmental factors and RLQ axes. Results Habitats and years had strong influences on trait patterns. After removing environmental variation caused by habitats and years, grazing became the most influential factor on trait responses. Traits negatively correlated with increasing grazing pressure were common to perennial grasses, such as long and entire leaves, anemochorous dispersal and rhizomatous growth. Positively correlated traits were those common to herbaceous, annual plants with a prostrate-creeping habit, compound leaves, high specific leaf area ( SLA) and exo- or endozoochorous dispersal. Some previously acknowledged grazing response traits, like growth form and plant height, were strongly influenced by variations in habitats and years and showed no significant correlation with grazing pressure. Conclusion We emphasize that some traits that respond to grazing may also vary under different habitat conditions and among years, especially in highly variable environments like semi-arid savannas. When analysing trait-environment relations we recommend using approaches that partition environmental variation, particularly when applying broad sampling schemes at larger geographical scales. [ABSTRACT FROM AUTHOR]