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Understanding the responses of different ontogenetic stages to environmental and human disturbance factors is essential for developing efficient conservation strategies for endangered plant species. We examined how three ontogenetic stages of a locally endangered tree species, Olea europaea subsp. cuspidata, responded to environmental factors and human disturbance in Hugumburda dry Afromontane forest in Ethiopia. We counted individual seedlings, saplings and adults of O. europaea in 70 20 × 20 m quadrats over ca. 2.8 ha, and measured biotic (woody species richness, canopy cover, aboveground tree biomass, herbaceous cover), abiotic (soil and topographic variables), and human disturbance factors (logging and tracks). To detect ontogenetic niche shifts, we compared observed vs. simulated locations of trees in the three life stages and how they related to the environmental and human disturbance factors. We found that the population structure of O. europaea showed generally low recruitment, with few seedlings per hectare compared with the abundance of saplings and adults. The probability of finding O. europaea individuals was influenced by biotic (woody species richness) and abiotic (soil depth, slope) environmental conditions and human disturbance (logging intensity), but the direction, strength and shape of the relationships differed between seedling, sapling and adult life stages, indicating ontogenetic niche shifts. All life stages showed a positive relationship with elevation. The observed environmental niches of the different lifestages of O. europaea, and their association with human disturbance levels, should be considered when conservation strategies are developed for this species. Human disturbance in terms of logging decreases the abundance of saplings, but may facilitate emerging seedlings through creation of gaps with improved light conditions. Recruitment is, however, very low in the study area, and seedlings should be protected from browsing to enhance survival. Woody species richness in general should be conserved to optimize conditions also for O. europaea saplings.

Understanding the effects of landscape fragmentation on global bumblebee declines requires going beyond estimates of abundance and richness and evaluating changes in community composition and trophic and competitive interactions. We studied the effects of forest fragmentation in a Scandinavian landscape that combines temperate forests and croplands. For that, we evaluated how forest fragmentation features (patch size, isolation and shape complexity, percentage of forest in the surroundings) as well as local flowering communities influenced bumblebee abundance, richness and community composition in 24 forest patches along a fragmentation gradient. In addition, we assessed the effect of fragmentation on bumblebee–plant network specialization (H2′), and potential inter- and intraspecific competition via shared plants. Patch isolation was associated with lower bumblebee abundance, whereas flower density was positively related to both bumblebee abundance and richness. Overall, forest fragmentation reduced the abundance of forest-specialists while increasing the abundance of open-habitat species. Patches with complex shapes and few flowers showed more generalized bumblebee–plant networks (i.e., fewer specific interactions). Patch shape complexity and the percentage of forest also modified inter- and intraspecific competitive interactions, with habitat generalists outcompeting forest specialists in fragmented areas. Understanding these mechanisms is necessary to anticipate to the impact of forest fragmentation on bumblebee decline., This study was supported by the projects 170532/V40 and 11551017, financed by the Norwegian Research Council and the Norwegian University of Life Sciences, respectively. During the writing of this manuscript AL was supported by a Ramón y Cajal (RYC-2015-19034) contract from the Spanish Ministry of Science, Innovation and Universities, the Spanish State Research Agency, European Social Funds (ESF invests in your future) and the University of the Balearic Islands. CGM was supported by project CGL2017-89254-R supported by Feder founds, the Spanish Ministry of Economy and Competitiveness and the Spanish Research Agency (FPI PRE2018-083185, Call 2018). JRP was supported by BIOINTFOREST funded by “Obra Social la Caixa” and “Fundación Caja Navarra” in the framework of UPNA's “Captación de Talento” program.

Habitat fragmentation threatens plant and pollinator communities, as well as their interactions. However, the effects of landscape fragmentation on the pollination of wild plant species are not well understood yet, partly because there are many correlated features in fragmented landscapes (e.g., decreased patch size, increased isolation, and patch complexity) whose influences are difficult to disentangle. Using a structural equation modeling approach, we assessed the direct and indirect effects of landscape fragmentation (patch size, isolation and complexity, percentage of surrounding land in forest) on the abundance, functional‐group richness, and evenness of pollinators of 24 habitat fragments within an agricultural landscape in Southern Norway. In addition, we studied how these variables affected visitation rates (visits per flower) and seed production (seed set, seed mass) in the four most abundant plant species in the area. Flower abundance was higher in larger and complex patches and decreased with the percentage of forest in the surroundings, while flower richness increased with patch complexity. We found a direct negative relationship between patch complexity and the overall number of pollinator visits that the habitat fragments received. Apart from this direct landscape effect, pollinator visits were mostly affected by the floral communities, with overall flower abundance and richness increasing both total number of pollinator visits and pollinator‐group richness, and flower richness having an additional negative influence on pollinator‐group evenness. Interestingly, we did not find any direct link between visitation rates and reproductive success for any of the study plant species. Instead, several landscape variables directly affected species seed production, although the effects of landscape on seed production were highly species specific. Patch complexity had a negative effect on seed production in two of the four focal species, while other components of the landscape had species‐specific effects. Increasing fragmentation of agricultural landscapes affects pollination interactions at the community level and the reproduction of wild plants. However, understanding the effects of fragmentation on seed production requires going beyond estimating visitation rates, since landscape effects on plant reproduction are not always related to overall interaction frequencies., This study was supported by the projects 170532/V40 and 11551017, financed by the Norwegian Research Council and the Norwegian University of Life Sciences, respectively. During the writing of this manuscript AL was supported by a Ramón y Cajal (RYC‐2015‐19034) contract from the Spanish Ministry of Science, Innovation and Universities, the Spanish State Research Agency, European Social Funds (ESF invests in your future) and the University of the Balearic Islands, and by project CGL2017‐89254‐R, financed by the Spanish Ministry of Economy and Competitiveness, Feder funds and the Spanish Research Agency.

Understanding the relationship between biotic, abiotic and disturbance factors in dry degraded forests is crucial for effective conservation of endangered plant species. We studied the relationship between two locally endangered tree species, Olea europaea subsp. cuspidata and Juniperus procera, and environmental conditions in the Hugumburda dry Afromontane forest in Northern Ethiopia. We surveyed species richness of woody plants, herbaceous plant cover, soil and human disturbance factors from 70 plots (20 m × 20 m). The abundance of both species was positively correlated with each other, and with woody species richness and elevation. Moreover, the biomass of both species correlated positively with total tree biomass and number of O. europaea cut stumps. The positive relationship between O. europaea trees and cut stumps suggests that illegal selective logging is taking place in O. europaea-dominated areas. Based on the observed relationships we predict that conserving woody species may result in an increase in the abundance of both O. europaea and J. procera in the forest.

Understanding how biotic interactions and abiotic conditions affect plant performance is important for predicting changes in ecosystem function and services in variable environments. We tested how performances of Astragalus rigidulus and Potentilla fruticosa change along gradients of biotic interactions (represented by plant species richness, abundance of the dominant plant species Kobresia pygmaea, and herbivory intensity) and abiotic conditions (represented by elevation, aspect, and slope steepness) across a semi-arid landscape in central Tibet. Redundancy analyses showed that the biotic variables explained 30 and 39 % of the variation in overall performance of A. rigidulus (P = 0.03) and P. fruticosa (P = 0.01), respectively. Abiotic variables did not contribute significantly to variation among A. rigidulus populations. Plant size decreased with species richness in both species and was larger on south- rather than north-facing slopes. Reproductive effort for both species was significantly negatively related to the abundance of K. pygmaea and both species had larger reproductive effort on south- rather than north- and west-facing slopes. The proportion of biomass allocated to sexual reproduction in P. fruticosa was negatively correlated with K. pygmaea abundance and herbivory intensity. The population density of P. fruticosa was positively related to elevation, species richness, and K. pygmaea abundance. We conclude that plant performance at a local scale was more strongly related to biotic than abiotic conditions, but different components of plant performance responded differently to predictor variables and the responses were species-specific. These findings have important implications for rangeland management under changing environmental conditions.

Motivation The BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community-led open-source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the Anthropocene. Main types of variables included The database contains 8,777,413 species abundance records, from assemblages consistently sampled for a minimum of 2 years, which need not necessarily be consecutive. In addition, the database contains metadata relating to sampling methodology and contextual information about each record. Spatial location and grain BioTIME is a global database of 547,161 unique sampling locations spanning the marine, freshwater and terrestrial realms. Grain size varies across datasets from 0.0000000158 km2 (158 cm2) to 100 km2 (1,000,000,000,000 cm2). Time period and grain BioTIME records span from 1874 to 2016. The minimal temporal grain across all datasets in BioTIME is a year. Major taxa and level of measurement BioTIME includes data from 44,440 species across the plant and animal kingdoms, ranging from plants, plankton and terrestrial invertebrates to small and large vertebrates. Software format .csv and .SQL., Global Ecology and Biogeography, 27 (7), ISSN:1466-822X, ISSN:1466-8238

Dominant woody species can determine the structure and composition of a plant community by affecting environmental conditions experienced by other species. We explored how dominant tree species affect the tree species richness, diversity, evenness and vertical structural heterogeneity of non-dominant species in wet and dry miombo woodlands of Tanzania. We sampled 146 plots from eight districts with miombo woodlands, covering a wide range of topographic and climatic conditions. We recorded 217 woody plant species belonging to 48 families and 122 genera. Regression analysis showed significant negative linear associations between tree species richness, relative species profile index of the non-dominant and the relative abundance of the dominant tree species (Brachystegia spiciformisandBrachystegia microphyllain wet, andBrachystegia spiciformisandJulbernardia globiflorain dry miombo woodlands). Shannon diversity and evenness had strong non-linear negative relationships with relative abundance of dominant tree species. A large number of small individual stems from dominant and non-dominant tree species suggesting good regeneration conditions, and intensive competition affecting survival. We suggest that dominant miombo tree species are suppressing the non-dominant miombo tree species, especially in areas with high recruitments, perhaps because of their important adaptive features (extensive root systems and ectomycorrhizal associations), which enhance their ability to access limited nutrients.

Summary Power line clearings are edge-creating disturbances in landscapes world-wide, but there have been few studies on their bordering vegetation. Our aim was to quantify edge effects on plant communities along such clearings in Norway and to identify factors that influence these edge effects. We surveyed understorey plant communities on either side of the power line clearing–forest edge at 51 sites, along four parallel transects at each site. Each transect had four plots located, respectively, in the clearing centre, clearing edge, forest edge and forest. We quantified the magnitude of edge effects (MEE) on either side by comparing edges with their corresponding ‘non-edge’ reference habitats. We also measured differences in species composition across the edge (clearing edge vs. forest edge). Habitat characteristics were sampled at plot and site level and from digital maps. Differences in species composition were greater between clearing centres and clearing edges than between forests and forest edges. Differences in species composition across the edge increased with edge contrast and forest productivity. Edge effects on species composition into the forest were smallest along north-facing edges, whereas those in the clearings increased with power line age. Species richness increased slightly towards the edge in forests but decreased considerably towards the edge in clearings. The direction and MEE on either side differed among functional groups. Edge contrast and edge aspect were the prime factors influencing the MEE into forests, whereas in clearings, these were influenced principally by tree regrowth in the clearings and by forest productivity. Synthesis and applications. Edge effects on plant communities bordering power line clearings were determined by factors that can be influenced by planners and managers. For existing power lines, management plans should differentiate between the following: (i) clearings through high conservation value forests, where edge effects into the adjacent forest should be limited; (ii) clearings that can act as replacement habitat for cultural landscape species, where maintaining open-canopy habitats should be prioritized; and (iii) ‘business-as-usual’ clearings, where continuing the current practice of cutting every 5–10 years is recommended.

Understanding how carbon storage and tree diversity are related in forests and woodlands is crucial for a sustainable flow of ecosystem goods and services. The goal of this study was to determine how tree species richness, evenness and environmental factors influence aboveground live tree carbon stocks (AGC) in two tropical vegetation types in Tanzania. We surveyed trees and sampled soil from 222 vegetation plots (20 m × 40 m) in montane forests (n = 60) and miombo woodlands (n = 162). We used a multimodel inference approach to determine how AGC related to tree species richness, evenness and environmental factors, and linear mixed effect models to test the role of tree sizes on the AGC-richness and evenness associations. AGC were related unimodally to tree species richness and evenness in the montane forest. Likewise, AGC in the miombo woodlands was positively related to tree species richness. AGC from small trees were related unimodally to tree species richness in both vegetation types. Apparently the AGC had both monotonically increasing and decreasing associations with all abiotic environmental factors in both vegetation types. We emphasize that both tree size, number of multi-stemed trees and environmental factors have an important role in determining how AGC are related to richness and evenness. Finally, management of montane forests and miombo woodlands of Tanzania to enhance ecosystem benefit, such as AGC, will require strategies that consider tree sizes, tree species richness, evenness and underlying environmental and disturbance factors.

Human influences affect plant species diversity and composition in many tropical forest ecosystems. We assess the effects of human use of woody plants on plant species composition and diversity in an intensively used open-access forest in Northern Ethiopia, and compare these community attributes with those of relatively intact forest patches. In each of 90 20 × 20 m plots in the open-access forest, we counted the number of woody plant species in different growth stages, and compared with those of 48 same-sized plots in nearby intact forest patches. Forest utilisation resulted in major shifts in dominance, with the dominant species in relatively intact forests being absent in open-access forest, whereas those species dominant in the open-access forest were absent from intact forests. Open-access forest had a lower total number of species, individuals and beta diversity than relatively intact forests. Intensive forest utilization has resulted in the dominance of disturbance-tolerant native and invasive species. Opuntia ficus-indica, regarded as a problem weed in Ethiopia, was abundant in the open-access forest. Dominance of a few species in the open-access forest could cause local and landscape-scale species loss. Relatively intact forest patches are therefore important for biodiversity conservation and ecological restoration in northern Ethiopia.

The species composition within communities is highly dependent on the rate of species immigration and whether immigrating species possess the functional traits required by the prevailing environmental conditions. Once established, random fluctuations in birth and death rates may reduce the diversity of ecologically equivalent species if local populations are not replenished by immigrating individuals. Consequently, three key processes drive community assembly: dispersal limitation, ecological filtering, and ecological drift. However, disentangling the relative contribution of these processes remains a challenge in community ecology. We used a binomial generalized linear mixed model to test whether the occurrences of solitary bees within 46 communities in southeast Norway were driven by (1) dispersal limitation, that is, the geographic distance to the nearest site where conspecifics occurred; (2) ecological filtering, that is, if forb species richness selected for non-Ericaceae-affiliated species; and (3) ecological drift, that is, if small, isolated communities were dominated by regionally common species. The regression slopes from the model for each potential driver of community composition were compared with those expected under a null model, in which species were treated as ecologically equivalent. Both dispersal limitation and ecological filtering influenced the probability of species occurring within communities. The occurrence of species decreased with elevation, and this relationship depended on the relative commonness of species and their floral preferences. For non-Ericaceae-affiliated species, the patterns of occurrence mirrored that expected under the null (neutral) model, resulting in the same patterns as would be expected under ecological drift. In contrast, the response of Ericaceae-affiliated species differed from what would be expected from the null model. Our results also indicate that processes leading to neutral dynamics in species compositions drive a large part of the gradient in species richness in Norwegian bee communities. These processes seem related to sampling effects so that large and interconnected communities have a higher probability of including regionally rare species than small, isolated communities. Our results suggest that targeting habitats—where the influence of ecological filtering is expected to be greater than that of neutral dynamics—can increase the success of habitat management plans aimed at promoting rare species.

Human disturbance, natural environmental conditions and seed dispersal are often inferred as important drivers of plant community richness and diversity in wetland ecosystems. However, plant functional groups within a plant community have different environmental requirements and may respond differently to human disturbance. Therefore, the understanding of the relative importance of these variables in determining community and functional groups richness and diversity is important for improved management and wise use of wetland resources. We collected data on vegetation and environmental conditions, human disturbance and seed dispersal from 60 plots of 20 × 50 m, to identify variables that potentially affect total species richness and Shannon-Wiener diversity of the grassland plant community at the Kilombero Valley wetland, Tanzania. We further tested whether important predictor variables for species richness and Shannon-Wiener diversity differ among graminoid, forb and shrub functional groups. Overall, our results suggest that environmental conditions, human disturbance and seed dispersal determine spatial variation in species richness and Shannon-Wiener diversity of the grassland vegetation. The total richness and Shannon-Wiener diversity and the richness of shrubs decreased with distance from the Kilombero River, whereas the total Shannon-Wiener diversity and the Shannon-Wiener diversity of graminoids decreased with the increase in grazing intensity. Shrub species richness was related to the spatial position of plots and decreased with total organic carbon of soil. Current increase in human disturbances through cattle husbandry and changes in natural environmental conditions (e.g. through water diversion and drainage) should be discouraged in order to restore and sustain biodiversity of the Kilombero wetland.

The negative effects of alien plant species on ecosystem structure and functions are increasingly recognised, and efforts to control these species are vital to restore degraded ecosystems and preserve biodiversity. However, we lack a full understanding of factors that determine alien species invasions along spatial gradients in herbaceous vegetation of tropical systems. We therefore examined the effects of community properties, environmental variables and human-related disturbance factors on the invasion of the alien grass Echinochloa colona (L.) Link at small- and large scales in the Kilombero Valley wetland, Tanzania. Generalized additive mixed models showed that E. colona abundance on a small scale was negatively related to above-ground biomass and evenness of resident species, whereas E. colona abundance was positively related to grazing intensity. On a large scale, biomass (negatively related to E. colona abundance) and distance to river (positive) were important in explaining E. colona abundance. These findings support the assertion that different factors may contribute to the invasion of alien plant species at different spatial scales, as also reported in many temperate systems. Overall, our results show that successful invasion of alien species is a function of plant community properties, human-related disturbance and favourable environmental conditions. Effective management strategies should consider mitigations that can increase the biomass and evenness of native species and a reduction of grazing pressure to restore the wetland and conserve biodiversity.

A central goal in ecology is to develop theories that explain the diversity and distribution of species. The evolutionary history of species and their functional traits may provide mechanistic links between community assembly and the environment. Such links may be hierarchically structured such that the strength of environmental filtering decreases in a step-wise manner from regional conditions through landscape heterogeneity to local habitat conditions. We sampled the wild bee species assemblages in power-line strips transecting forests in south-eastern Norway. We used altitude, landscape diversity surrounding sites and plant species composition, together with total plant cover as proxies for regional, landscape and local environmental filters, respectively. The species richness and abundance of wild bees decreased with altitude. The reduction in species richness and abundance was accompanied by a phylogenetic clustering of wild bee individuals. Furthermore, regional filters followed by local filters best explained the structure of the functional species composition. Sites at high altitudes and sites with Ericaceae-dominated plant communities tended to have larger bees and a higher proportion of social and spring-emerging bees. When Bombus species were excluded from the analysis, the proportion of pollen specialists increased with the dominance of Ericaceae. Furthermore, we also found that the taxonomic, phylogenetic and functional compositional turnover between sites was higher in the northern region than in the southern part of the study region. Altogether, these results suggest that regional filters drive the species richness and abundance in trait-groups whereas local filters have more descrete sorting effects. We conclude that the model of multi-level environmental filters provides a good conceptual model for community ecology. We suggest that future studies should focus on the relationship between the biogeographical history of species and their current distribution, and on the assumption that closely related species do indeed compete more intensely than distantly related species.

The bees (Hymenoptera: Apiformes) are important pollinators in many ecosystems, but their diversity has declined in Europe during the past century, mainly due to habitat loss. However, some of the habitat requirements of wild bees are met in anthropogenic landscape elements, such as road sides, power-line strips and field edges. Moreover, as the bee species assemblages change throughout the season the habitat requirements of the bee fauna may change accordingly. Understanding such seasonally distinct responses of solitary bees with different phenologies may be of high value for local conservation planning. The purpose of this study was to examine if the habitat quality of field edges for solitary bees change throughout the season, and how this temporal variation relates to local habitat and landscape conditions. By sampling solitary bees in 18 field edges in southeast Norway throughout the season we found that the species richness and abundance of bees was highest in sun exposed field edges, independently of the season. However, we found phenologically distinct responses to the landscape context. Moreover, field edges situated in landscapes with a high proportion of forests and semi-natural landscape elements hosted the most phenologically diverse bee species assemblages. We conclude that in order to fulfil the habitat requirements of bee species assemblages throughout the season, one should conserve and direct habitat restoration schemes towards increasing sun exposure at field edges with a diverse flora and a high proportion of semi-natural areas in the vicinity.

Plant community properties such as species richness, evenness, and composition vary along environmental gradients. Arid and semi-arid ecosystems, such as the central Tibetan Plateau, are thought to be sensitive to changes in temperature and water availability, and also influenced by a long history of herbivore grazing. We used linear mixed effect models and Canonical Correspondence Analysis to explore how plant community properties varied along gradients of elevation, soil moisture, grazing intensity, solar radiation, ground surface roughness (ground concavity), and pika abundance in an alpine meadow ecosystem in central Tibet. We found that species richness increased with elevation. Species evenness increased with soil moisture at lower elevation, but decreased with soil moisture at higher elevation. Species composition was significantly associated with all environmental variables except solar radiation. The abundance of the dominant plant species, K. pygmaea, which is driven primarily by soil m...

Woody plant encroachment alters the structure and function of rangeland ecosystems. The objective of this study was to explore the association between woody plant encroachment and various ecosystem properties (i.e. vascular plant species diversity, richness, evenness, soil organic matter, herbaceous biomass, leaf litter and bare ground cover) in a semiarid savanna rangeland, and also to test whether the relationships were influenced by woody species composition, elevation and site. We carried out a vegetation survey in four rangeland sites in the lower Omo region of southwestern Ethiopia, and regressed each one of the ecosystem properties, separately, against woody plant density, elevation and site using multiple linear regressions. We found that vascular plant species diversity, richness and evenness increased with woody plant density, most likely due to increased spatial heterogeneity and soil microclimate improvement. Bare ground cover increased significantly, whereas herbaceous biomass and soil organic matter did not respond to woody encroachment. In a subsequent investigation, we used a redundancy analysis to assess whether ecosystem properties were influenced by the identity of encroaching woody plant species. Species diversity and richness responded positively to Lannea triphylla, whereas leaf litter responded positively to Grewia tenax and G. villosa. Our findings suggest that woody plant encroachment in a semiarid rangeland does alter ecosystem properties. However, its impact is highly variable, influenced by a set of factors including the level of encroachment and identity of encroaching woody species.

Low nitrogen (N) supply is a limiting factor for plant growth in most terrestrial ecosystems. N-fixing legumes therefore have the potential to facilitate surrounding vegetation by increasing soil N levels. This effect should be especially pronounced in low-productivity habitats where ambient soil N levels are low, such as in alpine areas. We examined whether plant species composition, community diversity measures, and soil N levels differed with and without the presence of two alpine legumes, Oxytropis lapponica (Wahlenb.) Gay and Astragalus alpinus L., in a Dryas octopetala heath at Finse, Norway. Species composition and richness differed between plots with and without Oxytropis in one of two study sites, as other plant species were positively associated with the legume. None of the measured community properties differed between plots with and without the presence of Astragalus. The contrasting influence of the two legume species corresponds to our findings of higher soil N levels below Oxytropi...

Pollinator decline can disrupt the mutualistic interactions between plants and pollinators and potentially affect the maintenance of plant populations. However, there is still little knowledge on how changes in pollinator abundance can affect seedling recruitment, which is essential for population persistence. We experimentally simulated a community-wide reduction in pollinator availability during four years to examine its effects on seedling recruitment in 10 perennial herbs in a Norwegian hay meadow. Our experimental reduction in pollinator availability significantly reduced community-wide seedling diversity. Overall seedling abundance was also consistently lower under reduced pollinator availability, although this effect was only significant when the most abundant plant species in the community was excluded from the analysis. Despite an overall negative effect on seedling abundance, the experimental reduction in pollinator availability had contrasting effects on individual plant species. This tended to cause a larger change in seedling species composition in the experimental than in the control plots after the four study years. Our study demonstrates for the first time a direct causal link between reduced pollinator availability and reduced plant diversity and abundance.

Cultivation of annual crops in the initial stage of reforestation has been commonly practiced in the tropics. In recent decades, however, cultivation of such areas has been discontinued, resulting in widespread abandoned settlements. In this article we used a former forest village settlement in Kenya, which had been cleared, cultivated and then abandoned, to study how natural vegetation recovers after such disturbances. Species richness, abundance, and composition of tree seedlings, saplings, adult trees, shrubs, and herbs were recorded in different zones, from a heavily degraded zone in the center of the settlement, through less disturbed transition zones (TZs), and in the surrounding secondary forest (SF). Species richness and abundance of tree seedlings, saplings, and adult trees increased gradually from the heavily degraded zone to the SF, whereas shrub and herb richness were the same for TZs and SF and abundance was lowest in the SF. Total species richness was highest in the SF. Some pioneer tree species were highly associated with the TZs, whereas sub-canopy tree species were associated with the SF. A group of tree species were not particularly associated with any of the four zones. Thus, these species might have good potential as restoration species. The results of our study contribute to the knowledge of natural regeneration in general, and of individual species characterizing the different stages of recovery of abandoned settlements in particular. Such information is urgently needed in designing ecologically sound management strategies for restoring abandoned forest settlements in tropical areas.

Slash-and-burn agriculture is an important driver of deforestation and ecosystem degradation, with large effects on biodiversity and carbon sequestration. This study was conducted in a forest in Madagascar, which consists of fragments of slash-and-burn patches, within a matrix of secondary and primary forest. By recording species richness, abundance, and composition of trees, shrubs, and herbs in fallows of various age and slash-and-burn history, and in the secondary and primary forest, we show how slash-and-burn intensity (number of cycles, duration of abandonment), years since last abandonment, and environmental factors (distance to primary forest and topography) affect the natural succession and recovery of the forest ecosystem. We used ordination analyses to examine how the species composition varied between the different successions stages, and to examine tree recruitment. Our results show shrub dominance the first years after abandonment. Thereafter, a subsequent increase in species richness and abundance of tree seedlings and saplings suggests a succession towards the diversity and composition of the secondary and primary forest, although a big gap between the oldest fallows and the secondary forest shows that this will take much more than 30 years. A high number and frequency of slash-and-burn cycles decreased tree seedling and sapling richness and abundance, suggesting that reducing slash-and-burn intensity will increase the speed of tree recruitment and fallow recovery. Trees can be planted into fallows to speed up vegetation and soil recovery, such that fallows can be usable within needed time and thus the extension of cultivated areas reduced. We recommend further testing of six potential species for restoration based on their early colonization of the fallows and their survival through vegetation succession.

We examined the relationship between plant community diversity (species richness, evenness) and stability in an alpine Dryas octopetala heath exposed to four years of warming (open top chambers) and nutrient addition at Finse, southern Norway. Furthermore, we examined if different functional types responded differently to the interaction between environmental change and initial community diversity. We used the temporal change in species composition, calculated as the sum of change in sample scores in detrended correspondence analyses, as a measure of variability (opposite of stability). Under ambient conditions, a high initial species richness was associated with less stability of the total species composition. Under experimental warming, initial high species richness and evenness were associated with a more stable subsequent vascular species composition. Vascular stability decreased, however, with higher species richness under nutrient addition. When warming and nutrient addition were combined, high init...

Variations in species richness and diversity at a local scale are affected by a number of complex and interacting variables, including both natural environmental factors and human-made changes to the local environment. Here we identified the most important determinants of woody species richness and diversity at different growth stages (i.e. adult, sapling and seedling) in a bamboo–deciduous forest in northeast Thailand. A total of 20 environmental and human disturbance variables were used to determine the variation in species richness and diversity. In total, we identified 125 adult, 111 sapling (within fifty 20 × 20-m plots) and 89 seedling species (within one hundred and twenty 1 × 1-m subplots). Overall results from stepwise multiple regression analyses showed that environmental variables were by far the most important in explaining the variation in species richness and diversity. Forest structure (i.e. number of bamboo clumps and canopy cover) was important in determining the adult species richness and diversity (R 2 = 0.48, 0.30, respectively), while topography (i.e. elevation) and human disturbance (i.e. number of tree stumps) were important in determining the sapling species richness and diversity (R 2 = 0.55, 0.39, respectively). Seedling species richness and diversity were negatively related to soil phosphorus. Based on our results, we suggest that the presence of bamboos should be incorporated in management strategies for maintaining woody species richness and diversity in these forest ecosystems. Specifically, if bamboos cover the forest floor at high densities, it may be necessary to actively control these species for successful tree establishment.

Anthropogenic landscape elements, such as roadsides, hedgerows, field edges, and power line clearings, can be managed to provide important habitats for wild bees. However, the effects of habitat improvement schemes in power line clearings on components of diversity are poorly studied. We conducted a large‐scale experiment to test the effects of different management practices on the species, phylogenetic, and functional diversity of wild bees in power line clearings (n = 19 sites across southeastern Norway) and explored whether any treatment effects were modified by the environmental context. At each site, we conducted the following treatments: (1) Cut: all trees cut and left to decay in the clearing; (2) Cut + Remove: all trees cut and removed from the plot; and (3) Uncut: uncleared. The site‐specific environmental context (i.e., elevation and floral diversity) influenced the species, phylogenetic, and functional diversity within bee species assemblages. The largest number of species was found in the Cut + Remove treatment in plots with a high forb species richness, indicating that the outcome of management practices depends on the environmental context. Clearing of treatment plots with many forb species also appeared to alter the phylogenetic composition of bee species assemblages, that is, more closely related species were found in the Cut and the Cut + Remove plots than in the Uncut plots. Synthesis and applications: Our experimental simulation of management practices in power line clearings influenced the species, phylogenetic, and functional diversity of bee species assemblages. Frequent clearing and removal of the woody debris at low elevations with a high forb species richness can increase the value of power line clearings for solitary bees. It is therefore important for managers to consider the environmental context when designing habitat improvement schemes for solitary bees.

Alpine and arctic ecosystems may be particularly vulnerable to climate change. We know little about alpine plant community responses to the predicted abiotic changes, or to possible changes in the biotic environment caused by climate change. Four years of experimental warming and nutrient addition altered dominance hierarchies, community structure, and diversity of an alpine biodiversity hotspot in south Norway. The previously dominant dwarf shrub Dryas octopetala was replaced by graminoids and forbs under nutrient addition and warming with nutrients. Community diversity declined due to decreased bryophyte and lichen richness and abundances, and dwarf shrub abundances. In controls and in plots with only warming, where Dryas maintained dominance, the relationships between changes in Dryas cover and changes in community parameters were negative, suggesting that Dryas controls community processes. Under nutrient addition, bryophyte and lichen diversity decreased with decreasing Dryas cover, probably due to increased competition from graminoids and forbs. The shift in dominance hierarchies changed community structure and dynamics through increased biomass, vegetation height, and competition for light. Community diversity dropped primarily because changes in the abiotic environment modified biotic interactions, highlighting that species interaction must be considered in climate change experiments and in models predicting climate change effects.

Human disturbance may change dominance hierarchies of plant communities, and may cause substantial changes in biotic environmental conditions if the new dominant species have properties that differ from the previous dominant species. We examined the effects of bamboos (Bambusa tulda and Cephalostachyum pergracile) and their litter on the overall woody seedling abundance, species richness and diversity in a mixed deciduous forest in northeastern Thailand. These bamboo species are gaining dominance after human disturbance. Our results show that seedling abundance and species richness were reduced by bamboo canopies. Seedling abundance and species diversity under bamboo canopies were affected by bamboo litter, whereas seedling abundance and species diversity outside bamboo canopies did not respond to the mixed-tree litter manipulation. Removal of bamboo litter increased seedling abundance and species diversity. However, bamboo litter addition did not affect seedling abundance or species diversity compared to either control or litter removal. This may indicate that the effect of natural amount of bamboo litter is as high as for litter addition in preventing seedling establishment by woody species and hence in minimizing resource competition. We conclude that undergrowth bamboos and their litter affect tree seedling regeneration differently from mixed-tree litter, causing changes in plant community composition and species diversity. Increased human disturbance, causing a shift in dominance structure of these forests, may result in a concomitant reduction in their overall woody species abundance, richness and diversity. Thus, management of bamboos by controlling their distribution in areas of high bamboo density can be an important forest restoration method.

We have limited understanding of how tropical canopy foliage varies along environmental gradients, and how this may in turn affect forest processes and functions. Here, we analyse the relationships between canopy leaf area index (LAI) and above ground herbaceous biomass (AGBH) along environmental gradients in a moist forest and miombo woodland in Tanzania. We recorded canopy structure and herbaceous biomass in 100 permanent vegetation plots (20 m × 40 m), stratified by elevation. We quantified tree species richness, evenness, Shannon diversity and predominant height as measures of structural variability, and disturbance (tree stumps), soil nutrients and elevation as indicators of environmental variability. Moist forest and miombo woodland differed substantially with respect to nearly all variables tested. Both structural and environmental variables were found to affect LAI and AGBH, the latter being additionally dependent on LAI in moist forest but not in miombo, where other factors are limiting. Combining structural and environmental predictors yielded the most powerful models. In moist forest, they explained 76% and 25% of deviance in LAI and AGBH, respectively. In miombo woodland, they explained 82% and 45% of deviance in LAI and AGBH. In moist forest, LAI increased non-linearly with predominant height and linearly with tree richness, and decreased with soil nitrogen except under high disturbance. Miombo woodland LAI increased linearly with stem density, soil phosphorous and nitrogen, and decreased linearly with tree species evenness. AGBH in moist forest decreased with LAI at lower elevations whilst increasing slightly at higher elevations. AGBH in miombo woodland increased linearly with soil nitrogen and soil pH. Overall, moist forest plots had denser canopies and lower AGBH compared with miombo plots. Further field studies are encouraged, to disentangle the direct influence of LAI on AGBH from complex interrelationships between stand structure, environmental gradients and disturbance in African forests and woodlands.

We examined the impact of Salix lapponum canopies on plantcommunity structure in five sites along a climatic gradient in aglacier foreland in alpine south Norway. Species richness is lowerinside canopies compared to outside in climatically relativelybenign communities, while species richness is not affected bycanopies in the most severe communities closest to the glacier.Differences in species composition inside and outside canopies, asjudged by detrended correspondence analysis, are greater in thebenign communities compared to the severe communities. Variationin the differences in species richness or composition outside andinside canopies within a community is related to differences inthe reduction of photosynthetically active radiation (PAR) bycanopies in only one community. Canopy size does not explaindifferences in species richness or composition between outside andinside canopies in any except one benign community. Our resultssuggest that species responses to canopies are individualistic,and that at the whole-community level negative and positiveimpacts of canopies on species occurrences cancel each other outin severe communities, whereas in benign communities negativeeffects dominate slightly over positive ones in their effects onspecies persistence inside canopies.