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Aims: Historical land‐use legacies and chemical soil characteristics both explain either directly or indirectly the habitat quality of Nardus grassland, which is protected under the European habitat directive. Yet the relative importance and complementarity of both sets of variables are generally unknown. This knowledge is also relevant for practical reasons, as historical land‐use variables can be used in desktop spatial analyses, whereas soil characteristics require field surveys to collect samples for laboratory analyses. To this end, we aim to disentangle the relative importance of historical land‐use legacies and soil chemistry for the Nardus grassland quality, and determine the potential of habitat suitability mapping for predicting potential restoration areas. Location: Natura 2000 grasslands in Flanders (northern Belgium). Methods: We compared the model performance of three generalized additive models (GAMs), using either land‐use history metrics, soil chemistry, or both as explanatory variables, with the Nardus grassland indicator species count as response. Results: All three models were able to predict areas suitable for at least three Nardus grassland indicator species with high sensitivity and specificity. However, a minimum of four indicator species are required for a favorable conservation status of Natura 2000 Nardus grasslands in Flanders. Using this threshold to detect high‐priority zones, the model based on historical land‐use variables resulted in a lower sensitivity than models which included soil chemistry. Conclusions: We suggest a two‐step approach, with an a priori desktop spatial analysis based on historical land‐use variables subdivided in a high‐priority zone and a lower‐priority zone. If the targeted area for restoration or conservation can be found within the high‐priority zone, additional soil analyses are only required to help guide conservation and restoration measures. If additional sites are considered within the lower‐priority zone, a field survey to collect additional soil data is recommended. [ABSTRACT FROM AUTHOR]

The dreams of Humboldt and many of his successors have not yet come true. Despite the great achievements of the last century, we still do not know the total number of vegetation types or the difference in the patterns of the distribution of diversity above and below the ground, we cannot predict all the effects of climate change on vegetation at the regional and global scale, we do not know the hidden and dark parts of species diversity in most ecosystems, nor are we able to make historical vegetation maps for many areas of the Earth. We also do not know the cultural contribution of many plant communities for the development of human populations and civilization, nor do we know the future recreational and therapeutical potential of vegetation (e.g., aromatherapy, ecotherapy). Geobotanical methods can effectively contribute to finding the answers to hot questions in current ecology. Since there are so many gaps in our geobotanical knowledge and so many young researchers still speechless with delight when looking at endless steppes, lush rainforests, tall-herbs, or colorful meadows, there is no doubt that geobotany will be a thriving and developing discipline in the future. Its driving force is the passion of researchers and admiration for the beauty of various types of vegetation and their dynamics as well as awareness of the need to protect them for generations to come.

The dreams of Humboldt and many of his successors have not yet come true. Despite the great achievements of the last century, we still do not know the total number of vegetation types or the difference in the patterns of the distribution of diversity above and below the ground, we cannot predict all the effects of climate change on vegetation at the regional and global scale, we do not know the hidden and dark parts of species diversity in most ecosystems, nor are we able to make historical vegetation maps for many areas of the Earth. We also do not know the cultural contribution of many plant communities for the development of human populations and civilization, nor do we know the future recreational and therapeutical potential of vegetation (e.g., aromatherapy, ecotherapy). Geobotanical methods can effectively contribute to finding the answers to hot questions in current ecology. Since there are so many gaps in our geobotanical knowledge and so many young researchers still speechless with delight when looking at endless steppes, lush rainforests, tall-herbs, or colorful meadows, there is no doubt that geobotany will be a thriving and developing discipline in the future. Its driving force is the passion of researchers and admiration for the beauty of various types of vegetation and their dynamics as well as awareness of the need to protect them for generations to come. [ABSTRACT FROM AUTHOR]

The uneven presence of the cork oak (Quercus suber L.) within its distribution range is not only determined by its climatic requirements but also by specific edaphic needs. Although most of the natural populations thrive in acidic soils deriving from metamorphic or volcanic rock outcrops, some cork oak populations are found growing in soils deriving from calcareous bedrock, which are considered less suitable. We carried out a multidisciplinary investigation at the south eastern edge of the Q. suber distribution range (Mountains of Palermo, NW Sicily), including soil, floristic, and vegetation surveys, aimed at: (i) assessing the native or introduced origin of some peculiar cork oak populations; (ii) describing the associated plant communities and soils; (iii) identifying the ecological factors which could explain the local adaptation to soils deriving from calcareous bedrock; (iv) discussing the ecological role played by this species in the study area and within its distribution range. The collected information suggest that the detected cork oak stands are native to these areas. We hypothesized that the co-occurrence of high fire frequency, high soil calcium content and erosion, which caused the intermixing of different parent materials, might favor its competitive interactions with other Mediterranean tree species, thus accounting for the local presence of Q. suber. The study of cork oak populations thriving in peculiar substrates at the driest end of the range could be of great importance for the future conservation of this species, which is expected to face growing threats in the coming decades.

Organisms with different life histories are able to act as indicators of different characteristics of their environment. Here, we compared the precision of habitat indication by the vegetation and soil microbial communities in four salt-affected pastures: annual open salt sward, Pannonic Puccinellia limosa hollow, Artemisia saline puszta and grassy saline puszta. Dissimilarity of habitats was evaluated by standardized principal component analysis (PCA) based on four different datasets: catabolic profiles of microbial communities in June (a) and September (b), composition of vascular vegetation (c) and physical and chemical properties of the soil (d). Procrustes analysis was used to quantify the resemblance between pairs of PCA ordinations based on soil properties (d) and various biotic communities (a, b, c). PCA ordination based on vegetation most closely matched the soil data-based ordination, thus vegetation appears to better indicate habitat conditions than soil microbial communities do. For microbial communities, a better agreement with the soil data-based ordination was reached in September than in June. Most probably, the long-lived sedentary habit of perennial plants in these communities requires adaptation to long-term average habitat conditions. In contrast, short-lived soil microbes can quickly follow environmental changes, thus the composition of soil microbial communities better reflect actual soil conditions.

Despite a growing awareness that the herbaceous layer serves a special role in maintaining the structure and function of forests, this stratum remains an underappreciated aspect of forest ecosystems. In this article I review and synthesize information concerning the herb layer's structure, composition, and dynamics to emphasize its rote as an integral component of forest ecosystems. Because species diversity is highest in the herb layer among all forest strata, forest biodiversity is largely a function of the herb-layer community. Competitive interactions within the herb layer can determine the initial success of plants occupying higher strata, including the regeneration of dominant overstory tree species. Furthermore, the herb layer and the overstory can become linked through parallel responses to similar environmental gradients. These relationships between strata vary both spatially and temporally. Because the herb layer responds sensitively to disturbance across broad spatial and temporal scales, its dynamics can provide important information regarding the site characteristics of forests, including patterns of past land-use practices. Thus, the herb layer has a significance that belies its diminutive stature. [ABSTRACT FROM AUTHOR]

LÁJER (2007) raised the problem of using a non-random sample for statistical testing of plant community data. He argued that this violates basic assumptions of the tests, resulting thus in non-significant results. However, a huge part of present-day knowledge of vegetation science is still based on non-random, preferentially collected data of plant communities. I argue that, given the inherent limits of preferential sampling, a change of approach is now necessary, with the adoption of sampling based on random principles seeming the obvious choice. However, a complete transition to random-based sampling designs in vegetation science is limited by the yet undefined nature of plant communities and by the still diffused opinion that plant communities have a discrete nature. Randomly searching for such entities is almost impossible, given their dependence on scale of observation, plot size and shape, and the need for finding well-defined types. I conclude that the only way to solve this conundrum is to consider and study plant communities as operational units. If the limits of the plant communities are defined operationally, they can be investigated using proper sampling techniques and the collected data analyzed using adequate statistical tools. [ABSTRACT FROM AUTHOR]

1 This review brings into focus what is known about the response of the herbaceous layer of forest ecosystems to increasing nitrogen deposition. The emphasis on forests in general is important for two reasons. First, forests often occupy areas receiving high rates of atmospheric deposition of N. Second, compared with herb-dominated communities, about which much is known regarding response to excess N, forests generally display greater biological and structural complexity. The more specific focus on the herbaceous layer – here defined as all vascular (herbaceous and woody) plants ≤ 1 m in height – is warranted because most of the species diversity of forests occurs in the herb layer. 2 Most responses of forest ecosystems to N saturation, defined here as ecosystem supply of N exceeding ecosystem demand for N, can be characterized by two complementary hypotheses, each emphasizing different facets of ecosystem structure and function. One focuses on ecosystem processes, such as net primary productivity, whereas the other addresses seasonal patterns of concentrations of in stream water. Although neither hypothesis considers the effects of chronically elevated N deposition on forest herbs, both share a prediction – a dramatic increase in availability of – that is relevant to forest herb response. Such a shift towards dominance has important implications for changes in herbaceous layer dynamics. For example, increases in soil pools can increase invasibility by exotic species. Also, because preferential use of vs. can be highly species-specific among forest herbs, predominance of availability can bring about further changes in herb layer species composition. Also important to forest herbs is the tendency for enhanced mobility of to increase mobility and decrease availability of essential cations, such as Ca2+. 3 The response of plant species of the herbaceous layer of forest ecosystems to excess N availability can arise from N-mediated changes in several processes. Here I identify six – competition, herbivory, mycorrhizal infection, disease, species invasions and exotic earthworm activity – and discuss how they respond to excess N and how this response affects the herb layer of forests. With the exception of the activity of exotic earthworms (which is correlated with, but not necessarily caused by, high N deposition), there is compelling evidence that all processes respond sensitively to N deposition and that this response generally leads to drastic shifts in species composition and decreases in biodiversity of forest herb communities. 4 A hypothesis is suggested – the nitrogen homogeneity hypothesis – that predicts loss of biodiversity in forest ecosystems experiencing chronically elevated N deposition. This hypothesis is based on the decrease in spatial heterogeneity of N availability that is typically high in forest soils under N-limited conditions. [ABSTRACT FROM AUTHOR]

An expansion of the foundations of the theory of landscape ecology can relocate its different approaches in a deeper biological vision. To this purpose, I directed my efforts towards comprehension of the landscape and of its main component—the vegetation mosaic—as a proper biological system. As suggested by Naveh, I have revised landscape ecology according to new scientific paradigms, ranging from the Principle of Emerging Properties to the “order through fluctuation” processes. Considering that a landscape is much more than a set of spatial characters, I tried to focus its ecological elements and processes, proposing new concepts (e.g., ecocenotope, ecotissue), new functions (e.g., biological and territorial aspects of vegetation), and new applications (e.g., evaluation of vegetation, etc.). This improves vegetation science through (1) a critical review of the limits of phytosociology in studying the landscape, (2) a more coherent study of both natural and anthropogenic vegetation, (3) a better understanding of transformation processes, (4) a confirmation of the necessity to abandon deterministic concepts (e.g., potential vegetation), and, especially, through (5) a new capacity for landscape vegetation diagnosis. [ABSTRACT FROM AUTHOR]

The article discusses the development of an automatic ordination and neural network (NN) which predict the conservation value of the habitat quality. It states that the NN classifier help evaluates the richness, nativeness, rarity and diversity of the species. It also notes that the classifier help assess the biological integrity of the plant communities.

Plants have considerable ability to respond to herbivory, both with (above-ground) regrowth and with increased defense. We simulated both leaf and shoot herbivory in controlled, replicated experiments on individuals of Acacia drepanolobium in Laikipia, Kenya. These experiments were carried out on individuals that had experienced different, experimentally controlled histories of large mammalian herbivory. Both forms of simulated herbivory were associated with compensatory regrowth. Branches whose shoots had been removed grew significantly more over the next year than paired control branches, fully compensating for the lost shoot length. Branches whose leaves were removed both grew faster and had more leaves one year later than did control branches. Shoot removal, but not leaf removal, increased the production of side shoots. However, because past herbivore pressure was negatively associated with net shoot growth, there may be a long-term cost of herbivory even when plants appear to fully compensate for herbivory in the short term. In contrast to the effects on growth, simulated herbivory did not significantly increase physical (spines) or chemical (tannins) defenses, and there were no significant negative correlations between compensatory growth and plant defense. [ABSTRACT FROM AUTHOR]

Wild bee communities were studied on one- to five-year-old set-aside fields with naturally developed vegetation (n=20), and old orchard meadows (n=4) to analyse effects of secondary succession on species diversity, resource use and associated life history traits. General theory predicts a steady increase of species richness with age of succession. In contrast, we found a first maximum in species richness of bees on two-year-old set-aside fields and a second on old meadows. Successional changes of bee communities were related to changes of vegetation. The transition from pioneer successional stages, dominated by annuals, to early successional stages, dominated by perennials, resulted in the highest species richness of flowering plants in the second year within the first five years of succession. Species richness of flowering plants was the best predictor variable for species richness of bees, whereas the cover of flowering plants correlated with the abundance of bees. Annual plants were visited more often and perennials less often than expected from their flower cover. Halictidae tended to prefer flowers of annuals, whereas Megachilidae, Apidae and Anthophoridae significantly preferred perennials. In departure from successional theory, body size, proportion of specialised bees and proportion of parasitic bees did not significantly increase with successional age, but number of generations and the proportion of soil-nesting bees decreased with successional age. Comparison of different management types showed that set-aside fields with naturally developed vegetation supported much more specialised and endangered bee species than set-aside fields sown with Phacelia tanacetifolia. [ABSTRACT FROM AUTHOR]

We investigate the potential use of structural characteristics of vegetation as predictors of the densities of pasture arthropods in three Azorean islands. Two types of upland pastures, recent sown pastures(3-4 years old) and wet semi-natural old pastures (more than 35 years old), were studied in three Azorean islands (S. Maria, Terceira andPico). Three arthropod assemblages, of particular importance in pasture habitats, were assessed: insect forb-feeders, insect grass-feeders and web-building spiders. These are numerically abundant and represent a range of feeding strategies. Point quadrats for plants and suction (Vortis) for arthropods were used as sampling methods. Several vegetation indices were investigated, but only three (cover abundance of perennial forbs, cover abundance of perennial grasses and the totalvegetation alpha-diversity) were good predictors of invertebrate abundance. Vegetation structure, defined by a Height Index, was of minorpredictive value. In sown and semi-natural pastureland, diverse and structurally complex pasture sites support more individual insect forb-feeders, grass-feeders and web-building spiders per unit area than less complex ones. [ABSTRACT FROM AUTHOR]

In this study, we investigated the effect of reindeer grazing on tundra heath vegetation in northern Norway. Fences, erected 30 yr ago, allowed us to compare winter grazed, lightly summer grazed and heavily summer grazed vegetation at four different sites. At two sites, graminoids dominated the heavily grazed zone completely, while ericoid dwarf shrubs had almost disappeared. In the other two areas, the increase of graminoids was almost significant. At one of the sites where graminoids dominated the heavily grazed area, we also measured plant biomass, primary production and nitrogen cycling. In this site, heavy grazing increased primary production and rate of nitrogen cycling, while moderate grazing decreased primary production. These results were inconsistent with the view that the highest productivity is found at intermediate grazing pressure. These results rather support the hypothesis that intensive grazing can promote a transition of moss-rich heath tundra into productive, graminoid-dominated steppe-like tundra vegetation. Moreover the results suggests that intermittent intensive reindeer grazing can enhance productivity of summer ranges. [ABSTRACT FROM AUTHOR]

Fragmentation of lowland tropical rain forests has resulted in loss of animal and plant species and isolation of remaining populations that puts them at risk. At Los Tuxtlas, Mexico, lowland rain forests are particularly diverse in the bat fauna they contain and while most of the forests have been fragmented by human activity, many of the fragments still harbor diverse assemblages of bat species. To assess the effectiveness of corridors, among other options, to ameliorate the negative effects of fragmentation, we investigated bat species richness and relative abundance in one 6 km long section of live fences (LF) bordering a dirt road and in three 6 km long sections of residual forest vegetation along the sides of three permanent streams (BS, MS, HS). Netting of bats resulted in the capture of 967 bats. At the LF site we captured 12 bat species, 15 at the BS site, 18 at the MS site and 23 at the HS site. Species richness was associated with average area of forest fragments within a 1000 m band on each side of each corridor (r=0.97, p=0.01). Only 28% of the species were common among sites. Frugivorous and insectivorous species accounted for 48% each of bat captures while nectarivores accounted for 3%, sanguinivores for 0.5% and carnivore-frugivores for 0.5%. Edge habitat species such as Pteronotus parnelli and Sturnira lilium accounted for 50% of the captures. Frugivorous species such as Carollia brevicauda, Vampyrodes caraccioli, Dermanura phaeotis, D. toltecus and A. jamaicensis accounted for another 25% of bat captures. Recaptures of bats indicated bat movements from forest fragments to corridors and between corridors, with recapture distances ranging from 200 to 2000 m. Within corridor recaptures separated by several months from the original recapture date indicated individual bat revisitation to these sites. We discuss the value of these corridors to bats as stepping stones in the fragmented landscape. [ABSTRACT FROM AUTHOR]

The distribution of the flora with different species attributes are investigated in two studies of forest ecosystems in Denmark. One study compared 17 forests with different degrees of management, the other study compared the flora of 25 old forests with that of 6 new forests. No effect of forest management could be detected in the distribution of species attributes in the flora, whereas the forest continuity was correlated with almost all of the 14 traits investigated. Species with heavy seeds, transient seedbanks, ant dispersed seeds, early and short flowering time, low stature and high extent of lateral spread were more common in old forests, while the proportion of species with small, short-lived seeds, epizoochorous dispersal, little lateral spread and later and longer flowering period was higher in new forests. In particular, Raunkiaers therophytes, and ruderal species were more common in new forests than in old. Differences in the effects of the two types of disturbance – forest management, and breaks in forest continuity – are discussed in relation to survival strategies of the forest flora. The importance of persistence ability in contrast to colonisation ability is stressed for many forest plants. [ABSTRACT FROM AUTHOR]

We investigated the relative contributions of size and growth form (biomass allocation) to competitive effects between grasses and shrubs in western Canada for two years. We measured the effects of grasses and shrubs on each other at the population level using removal experiments in natural vegetation. In prairie where shrub abundance was low, shrubs suppressed grasses as much as grasses suppressed shrubs, even though shrubs had six times more standing crop. In adjacent brush clumps, however, where shrub standing crop was 37 times grass standing crop, shrubs suppressed grasses strongly, whereas grasses did not suppress shrubs. Shrubs reduced available soil nitrogen more strongly than grasses did, but shrubs and grasses did not differ in their effects on light or soil water. On a per-gram basis, however, shrubs had smaller effects on light, nitrogen, and water consumption than grasses did. In spite of their smaller per-gram effects on resources, the secondary growth of shrubs allowed them to accumulate more mass and height, and to eventually displace grasses. During this process, competition between the woody and the herbaceous growth form changed from symmetric to asymmetric. [ABSTRACT FROM AUTHOR]

Interspecific variation in leaf life span reflects the variation in nutrient conservation ability among different plant species and is considered to be associated with nutrient availability in the characteristic habitat. As defoliation interferes with nutrient conservation by the long-lived leaves, we hypothesized that disturbance rate is another important environmental factor working as a selective force on interspecific variation in leaf life span. In order to investigate this, we measured leaf life span of 32 grass species in mature garden-grown individuals. Variation in leaf life span was compared to measured leaf traits, to available data on species occurrence along gradients of nutrient availability and disturbance, and to published relative growth rates of the species. Leaf life span was associated positively with leaf tissue mass density and negatively with specific leaf area. Leaf life span correlated negatively with the disturbance rate in the characteristic habitat of a species, but not with nutrient availability. The latter relationship did not come about due to the long leaf life spans of species from nutrient-rich habitats with a relatively low disturbance rate, and to some extent also due to the short leaf life spans of annual species from relatively nutrient-poor sites. We conclude that although leaf longevity is an important means of reducing nutrient losses, this is a selective advantage only if the plant is not subjected to frequent defoliation. The frequently postulated association between leaf life span of a species and nutrient availability in its characteristic habitat may occur among species of habitats with positively correlated nutrient availability and disturbance rate. Leaf life span is negatively associated with seedling RGR, but there may be deviations in this relationship due to species with contrasting characteristics at seedling stage and at maturity. [ABSTRACT FROM AUTHOR]

Grasslands are often characterised by small-scale mosaics in plant community composition that contribute to their diversity. Although above- and belowground biota can both cause such mosaics, few studies have addressed their interacting effects. We studied multi-trophic interactions between aboveground vertebrate grazers, subterranean ants, plant-pathogenic soil biota (especially nematodes) and the vegetation in a temperate grassland. We found that when rabbits and cattle locally omit vegetation patches, yellow ants (Lasius flavus ) respond to the taller vegetation by digging up more sand from deeper soil layers (hence making taller nest mounds), probably to maintain sufficiently high soil temperatures. We found that this ant digging affects other soil biota, as the mounds contain fewer plant-parasitic and fungivore nematodes. Also, the mounds have lower moisture content and soil bulk densities, and higher pH and available nutrient content than the directly surrounding soil. The clonal sedge Carex arenaria grows vigorously on the mounds, producing more shoots and shorter rhizome internode lengths than in surrounding vegetation. Other plant species, such as the grass Festuca rubra , dominate the surrounding vegetation. A greenhouse bioassay experiment revealed that harmful soil organisms (as plant-parasitic nematodes and pathogenic fungi) outweighed the effect of beneficial organisms (e.g., mycorrhizae) in this system. Rhizome biomass and shoot production of C. arenaria were indeed inhibited less by biota in soil from ant mounds than by biota in soil from the surrounding vegetation. However, the total biomass production of C. arenaria was inhibited as strongly in both soil types. F. rubra was inhibited more strongly by biota in the surrounding soil. We suggest that various direct and indirect interactions between above- and belowground biota can contribute to community mosaics and hence diversity in grasslands. [ABSTRACT FROM AUTHOR]

We examined the occurrence of vertically via host seeds transmitted endophyte infections of 14 grass species in natural populations in Finland and totally 97 agricultural cultivars of 13 grass species. Although endophyte infections were widespread in native grass species, overall endophyte occurrence and frequencies were lower than published reports have suggested. In natural populations, 10 out of 14 grass species examined harbor fungal endophytes in their seeds. The highest species-specific mean incidences of endophyte infected plants in infected populations were found in Agrostis capillaris, Festuca arundinacea, F. ovina, F. pratensis, F. rubra and Phleum pratense (67%, 98%, 29%, 42%, 32% and 33%, respectively). Mean incidences were <20% in Dactylis glomerata, Deschampsia flexuosa, D. cespitosa and Elymus repens, and no infections were detected in Calamagrostis lapponica, C. epigejos, Alopecurus pratensis and Phalaris arundinacea. However, we detected a very high variation in infection incidences among natural populations and a large proportion of populations was, indeed, endophyte-free. This supports the ideas that 1) endophytic fungi provide selective advantage of infected grasses to their uninfected conspecifics in some habitats, and/or 2) fungi are occasionally transmitted horizontally by spores. In grass cultivars, endophyte infected seeds were detected only in F. pratensis and Lolium perenne, and endophyte frequencies were either very high or very low. Cultivars of 11 other grass species were endophyte-free. [ABSTRACT FROM AUTHOR]

Resprouting is an efficient means by which woody plants regain biomass lost during disturbance, but there is a life history trade-off that occurs in all disturbance regimes between investment in the current generation through resprouting vs investment in future generations at the same or more distant sites. The relative allocation to resprouting vs seeding in woody plant communities is dictated by the nature of disturbance regimes. Resprouting is the predominant response to the least severe disturbance regimes, but is also a common response in disturbance regimes of high severity, those that destroy most or all above-ground biomass, and which occur at medium to high frequency. The response to disturbance either by resprouting or seeding is dictated by the site's productivity. We present a comprehensive model for relative allocation to resprouting vs seeding across a range of disturbance regimes. Competition between plants that mostly seed vs those that mostly resprout should accentuate differences in allocation along a gradient of disturbance frequency. However the patchy nature of disturbance in time and space, coupled with gene flow among populations undergoing different disturbance regimes, ensures that it is unlikely that either resprouting or seeding will be the sole response in most plant communities at most disturbance frequencies. Additional influences on resprouting in woody plant communities include changes in allocation during the lifespan of individual plants and phylogenetic constraints that are expressed as biogeographic patterns. [ABSTRACT FROM AUTHOR]

The dwarf shrub Indigofera spinosa, indigenous to arid and semi-arid rangelands of northeastern Africa, is an important food source for livestock. Proper management of the shrub requires improved understanding of the effects of grazing and climatic variability on aboveground dry-matter allocation. Between 1986 and 1990, we compared the temporal variability of aboveground dry-matter allocation to different plant biomass compartments. We also compared dry-matter transfers between components; total live biomass to litter, standing dead to litter and live biomass to standing dead between continuously grazed and an ungrazed treatments. Partitioning of combined total dry-matter production among different structural organs (called allocation ratio) is influenced by phenological changes, episodic rainfall and herbivory. Dry-matter production in the grazed treatment responded more markedly to episodic rainfall events more than in the ungrazed treatment. Exclusion of grazers failed to improve the relative growth rate (RGR) of shrub biomass, while grazing improved it. RGR declined in the ungrazed treatment following the accumulation of standing dead dry-matter, while in the grazed treatment it declined following the shedding of leaves. The shrub allocated more to total live biomass than to standing dead. Greater reduction of total live allocation ratio in the grazed than in the ungrazed treatment occurred during a dry year. The ungrazed treatment had higher standing dead allocation ratio than did the grazed treatment. Plants transferred more dry-matter from total live biomass compartment to litter, than from standing dead to litter or from total live biomass to standing dead independent of treatment. The rates of transfer were higher in the ungrazed than in the grazed treatment. The results suggest that I. spinosa has evolved to respond to climatic variability and grazing by allocating dry-matter differently between various compartments. [ABSTRACT FROM AUTHOR]

Organisms with different life histories are able to act as indicators of different characteristics of their environment. Here, we compared the precision of habitat indication by the vegetation and soil microbial communities in four salt-affected pastures: annual open salt sward, Pannonic Puccinellia limosa hollow, Artemisia saline puszta and grassy saline puszta. Dissimilarity of habitats was evaluated by standardized principal component analysis (PCA) based on four different datasets: catabolic profiles of microbial communities in June (a) and September (b), composition of vascular vegetation (c) and physical and chemical properties of the soil (d). Procrustes analysis was used to quantify the resemblance between pairs of PCA ordinations based on soil properties (d) and various biotic communities (a, b, c). PCA ordination based on vegetation most closely matched the soil data-based ordination, thus vegetation appears to better indicate habitat conditions than soil microbial communities do. For microbial communities, a better agreement with the soil data-based ordination was reached in September than in June. Most probably, the long-lived sedentary habit of perennial plants in these communities requires adaptation to long-term average habitat conditions. In contrast, short-lived soil microbes can quickly follow environmental changes, thus the composition of soil microbial communities better reflect actual soil conditions. [ABSTRACT FROM AUTHOR]

We tested the hypothesis that roads in arid central Australia modifyroadside hydrology and nutrient patterns creating better habitat formistletoes (Loranthaceae). In two areas of mulga woodland near AliceSprings where mulgas (Acacia aneura) are the principal mistletoe host, we compared mistletoe abundance, and host foliar water and nutrient content between roadside and interior (100 m from the road) sites. Mistletoes were significantly more abundant close to roadsides than at interior sites and mulgas had significantly higher foliar water contents at roadside compared to interior sites. Mulga foliar P and N levels were not, however, significantly different between roadside and interior sites. We conclude that roads exert a strong influence on the adjacent biota in arid central Australia primarily through facilitating water infiltration at roadside sites. [ABSTRACT FROM AUTHOR]

Plant community composition and its likely environmental controls were investigated for 200 sample plots (each 100 m2) from Mediterranean-type vegetation in the Little Desert National Park, Victoria. TWINSPAN classification revealed four readily identifiable vegetation types; mallee-broombush, heathland, stringybark open woodland, and an assemblage intermediate between mallee-broombush and heathlandreferred to here as broom-heath. Mallee-broombush was found on Parilla Sands characterized by high Ca levels relative to heathland and stringybark open woodlands on unconsolidated Lowan Sands. The first axis of a 2 dimensional non-metric MDS ordination also divided heathlands (high axis scores) from mallee-broombush (low scores), while the second separated these vegetation types from stringybark woodlands and broom-heath. Vector-fitting revealed significant correlations betweenthe locations of samples in ordination space and exchangeable soil Ca, soil colour, aspect and Shannon-Weiner diversity. Highest species richness/diversity was associated with the ecotonal area between Parilla and Lowan Sands (i.e. broom-heath) where a number of species characteristic of different assemblages had overlapping ranges. The fire-sensitive conifer, Callitris rhomboidea, was preferentially located in stringybark woodland and broom-heath vegetation types. Its presencewas positively associated with high species richness and aspects having a southerly component. Four Callitris stands sampled for population structure were all > 40 years old and showed evidence of interfirerecruitment from seeds released by old, serotinous cones. Overall, results suggest that variations in plant community composition and structure in the eastern block of the Little Desert are primarily due tovariations in soil properties associated with the distribution of the two dominant substrate types, Parilla Sand and Lowan Sand. However,the interplay of topography and fire behaviour has probably been more impo [ABSTRACT FROM AUTHOR]

The native annual Sorghum populations of the Australian wet-dry tropics are highly resilient to dry season fires. During the early wet season, however, fires that occur after the new grass population has emerged can cause catastrophic population crashes. We examined savanna plots that had been burnt in this way, and compared them with adjacent unburnt plots. We found that Sorghum densities in the burnt plots were lower on average by a factor of 10, but that some fires had reduced the density only to one-third of the unburnt plots. It is not clear whether these differences relate directly to site or seasonal factors, or to differences in the way the burning was carried out. Other vegetation components responded to the fires differently: forbs (dicotyledonous herbs) increased in cover, while perennial grasses, woody plants, and overall species richness, were not significantly affected.The amount of leaf litter declined. A population model for Sorghum based on the demography of unburnt populations predicted that they should recover from a wet season burn, taking 7-16 years to return to normal densities. However, the actual field populations did not seem tobe recovering, suggesting that wet season fires not only lower densities, but may also fundamentally change population processes in theseannual grasses. [ABSTRACT FROM AUTHOR]

A model for tree influence on understory vegetation in boreal spruceforests is developed according to the principles of ecological fieldtheory. Single-tree influence at a point in space was modeled as theproduct of two factors: (1) the size (diameter at breast height) of the tree relative to that of the largest tree encountered in the area; a parameter specifies the weight given to large trees), and (2) thepoint4s distance from the center of the stem (one parameter specifies the zone of influence of a tree in crown radius units, another parameter specifies the relative weight given to closeness to, versus distance from, the tree stem). The total tree influence at the point is calculated from single-tree influence by a multiplicative model. Optimal choice of model parameters was found by maximizing the eigenvalueof a constrained ordination (CO) axis, obtained by use of the tree influence index as the only constraining variable. Two CO methods, Redundancy Analysis (RDA) and Canonical Correspondence Analysis (CCA), were applied to one vegetation data set with two subsets from a borealspruce forest in SE Norway. The eigenvalue of CO axes constrained bythe optimized tree influence index differed between the two CO methods, amounting to 9-10% of total inertia with RDA and 3% with CCA. Thehigher eigenvalue-to-total-inertia ratio with RDA was interpreted asdue mainly to the low species turnover (low beta diversity) along the tree influence gradient, as demonstrated by the monotonic responsesof a majority of species to tree influence. The linear species response model in RDA was therefore more appropriate in this case than theunimodal model of CCA. Vascular plants and cryptogamic species differed with respect to optimal parameters in the tree influence model. These differences were in accordance with throughfall precipitation and time in hydrated state as the most important determinants of cryptogamic species performance, and soil moisture and incoming radiation as the most [ABSTRACT FROM AUTHOR]

A long-term research programme, conducted mainly in northern England, has involved field surveys (1965-77), laboratory screening (1974-96), monitoring of permanent plots (1958 to date) and manipulative experiments (1987 to date). The so-called C-S-R classification of plant functional types developed from all this activity. Patterns of covariation among the traits used in the classification have recently been validated in this journal. The C-S-R classification appears to be applicable to vegetation in general. It thus has considerable potential for interpreting and predicting vegetation and ecosystem properties ona world-wide scale. However, to realize this potential we need to develop simplified procedures to extrapolate the C-S-R system to the many species which have not been the subject of previous ecological investigation. Here we describe a rapid method for attribution of C-S-R type and we test its accuracy in Britain by comparing it with an independent classification based upon more laborious procedures. The new method allocates a functional type to an unknown herbaceous subject using few, simple predictor variables. We have developed spreadsheets to perform all of the necessary calculations. These may be downloadedfrom the UCPE website at http://www.shef.ac.uk/uni/academic/N-Q/nuocpe, or obtained by direct application to the E-mail address ucpe@sheffield.ac.uk [ABSTRACT FROM AUTHOR]

The effects of pasture management options (sowing introduced legumesand grasses, timber treatment, applying fertilizer, cultivation before sowing, and stocking rate) on species diversity were measured at two experimental sites (Hillgrove and Cardigan) near Charters Towers, northeast Queensland. Species were divided into three groups (sown, native and exotic) and diversity was measured as species density (number of species recorded in each plot and number of species/quadrat) annually from 1982 to 1992. The responses of individual native and naturalized species to treatment were also determined. All management options affected diversity but the responses varied with site and season, and with the different measurement scales. The density of sown species either increased or was unaffected by all the management options;there were no significant decreases. The density of native species showed both positive and negative responses; it increased at high stocking rates and with tree killing at Hillgrove, and decreased with pasture sowing and cultivation. The density of exotic species increased as stocking rate was increased and decreased when pastures were sown (although not at the quadrat scale at Hillgrove). Overall the most diverse vegetation was on plots grazed at high stocking rates; at the plot scale these were native pastures but at the quadrat scale the sown pastures had more species. Among the native and naturalized species, only Portulaca spp. were more frequent on the oversown plots than the native pasture plots; 48% (Hillgrove) and 68% (Cardigan) of the species were less frequent on the oversown plots. Fertilizer application had little effect on species frequencies, while timber treatment resulted in both increases and decreases in frequency of a small numberof species. The species were divided into four groups on the basis of their responses to stocking rate: a grazing-sensitive group (e.g. Themeda triandra), two grazing-tolerant groups which either slightly decr [ABSTRACT FROM AUTHOR]

Invasion by exotic species following clearfelling of Eucalyptus regnans F. Muell. (Mountain Ash) forest was examined in the Toolangi State Forest in the Central Highlands of Victoria. Coupes ranging in age from <1- to 10-years-old and the spar-stage forests (1939 bushfire regrowth) adjacent to each of these coupes and a mature, 250-year-old forest were surveyed. The dispersal and establishment of weeds was facilitated by clearfelling. An influx of seeds of exotic species was detected in recently felled coupes but not in the adjacent, unlogged forests. Vehicles and frequently disturbed areas, such as roadside verges, are likely sources of the seeds of exotic species. The soil seed bank of younger coupes had a greater number and percentage of seeds of exotics than the 10-year-old coupes and the spar-stage and mature forests. Exotic species were a minor component (< 1 % vegetation cover) in the more recently logged coupes and were not present in 10-year-old coupes and the spar-stage and mature forests. These particular exotic species did not persist in the dense regeneration nor exist in the older forests because the weeds were ruderal species (light-demanding, short-lived and short-statured plants). The degree of influence that these particular exotic species have on the regeneration and survival of native species in E. regnans forests is almost negligible. However, the current management practices may need to be addressed to prevent a more threatening exotic species from establishing in these coupes and forests. [ABSTRACT FROM AUTHOR]

The objective was to determine the effects of root and shoot competition on seedling establishment of the unpalatable grasses Stipa gynerioides and S. tenuissima in a native grassland of central Argentina dominated by the palatable grass S. clarazii. Seeds of the two unpalatable species were sown in natural occurring microsites with shoot androot competition from the palatable species, and in artificially created microsites without either shoot competition or shoot and root competition. In addition, fresh seeds of the unpalatable species were subjected to daily alternating temperatures under laboratory and fieldconditions to determine the effect on seed dormancy and germination.Seedling establishment of S. gynerioides and S. tenuissima occurred only in microsites without shoot and root competition. Also, the fluctuation of temperature near the soil surface in these microsites reduced dormancy and promoted rapid germination in both species. Our results support the hypothesis that, in swards dominated by palatable grasses, vegetation gaps of low competitive pressure favour seedling establishment of unpalatable grasses. It is suggested that the creation of these gaps by overgrazing can be an important mechanism in the process of species replacement in native grasslands. [ABSTRACT FROM AUTHOR]

Successful ecosystem restoration requires the re-establishment of fundamental ecological processes, many of which involve plant-animal interactions. Myrmecochory (seed dispersal by ants) is a particularly important plant-animal mutualism in Australia, but little is known about its response to either disturbance or restoration following disturbance. Here we investigate the effects of disturbance on seed dispersal by ants, and the extent to which the ant-seed relationship has re-established at sites undergoing rehabilitation, at Ranger uranium mine in the seasonal tropics of Australia's Northern Territory. We focused on the composition of seed-dispersing ant assemblages, rates of seed removal by ants, and the dispersal curves generated by ants, as determined by observations of removal from seed depots. Ten sites were studied, comprising four 'natural' (undisturbed) sites representing arange of savanna habitats occurring in the region, four disturbed sites representing a range of habitat disturbance but with intact soil,and two waste rock sites subject to preliminary revegetation trials.A total of 22 ant species from 10 genera were observed during 154 observations of seed removal, most commonly Rhytidoponera aurata (53 records), Monomorzum (rothsteini gp) sp. 1 (14), Iridomyrmex sanguineus(13), Iridomyrmex pallidus (12) and Pheidole sp. 3 (10). Removal rates (over 3 h) averaged 29% across all sites and time periods, varyingmarkedly both between and within sites. However, mean rates of removal were similar between natural, disturbed and waste rock sites (29%,28% and 31%, respectively). A high incidence (62% of all depots) of `aril robbing' by ants (primarily Monomorium spp.) eating arils in situ, without removal, was observed. Dispersal distances varied markedly between ant species, with Iridomyrmex sanguineus having both the highest mean (7.25 m) and maximum (13.08 m) dispersal distances. Species of Pheidole typically dispersed seeds less than 0.5 m, and Meranoplus, Mo [ABSTRACT FROM AUTHOR]

The influence of factors associated with fire on seed germination ofAustralian native species is generally well documented, but examplesinvolving the use of smoke as a fire analogue for ecological research remain limited. The role of season of treatment in the efficacy of smoke as a promotive germination agent was investigated over two growing seasons using natural soil stored seedbanks in Banksia woodland near Perth, Western Australia. Smoke was applied to unburnt sites in the autumn, winter and spring of 1994. Germinant emergence and seedling survival of 37 species representing 18 families was monitored in both unburnt sites and in adjacent, recently burnt sites until the second spring after treatment (October 1995). Recruitment from seed was found to be profoundly affected by the season in which dormancy breaking treatment had been applied. The promotive effect extended beyond the initial year of application. For the majority of the species investigated, application of smoke to unburnt sites in autumn promoted a significantly greater germination response than treatment in winter orspring. In only three cases (introduced annuals, the Fabaceae and Hibbertia amplexicaulis) did autumn smoke treatment not yield better germination than in summer-burnt counterparts. However, in almost half of the cases examined, proportions of seedlings surviving past their first summer after emergence in burnt areas were consistently greaterthan those in smoked or untreated sites. Most notably, no seedlings emerging during the spring of the first year of study survived into the following summer. Implications of the results with respect to future seed bank research and management of native vegetation are discussed. [ABSTRACT FROM AUTHOR]

Heterogeneous soil resources may cause vegetation heterogeneity on abandoned fields and grasslands. We tested effects of resource enrichment and heterogeneity at scales from a single plant to small plot community on vegetation composition and rate of early succession on two fields. Enriched plots of three heterogeneity scales were establishedby fertilizing alternate trenched subplots. Unenriched plots were established with trenched but unfertilized subplots as controls for trenching heterogeneity. Vegetation was censused every other year for six years. We asked if nutrient enrichment or heterogeneity affects vegetation diversity or rate of succession, and if resource effects change over time. Species richness was lower in fertilized plots on both fields. Species turnover reflected an early gain of species on one field and loss on the other. Turnover differed between enriched and unenriched plots, but not over heterogeneity scales. Plot enrichment, but not heterogeneity, influenced initial abundance and establishment of a dominant, Ambrosia trifida, on one field and the later dominant Solidago altissima on the other field. Ambrosia responses slowed, and Solidago responses increased, succession on enriched plots. There wasa weak trend of increasing strength of soil resource effects over time in both fields. We found no strong evidence that vegetation trackssoil resource heterogeneity of the patch sizes, arrangement, and contrast tested. However, differential growth of the dominant species and richness of minor taxa between enriched and unenriched plots created vegetation heterogeneity on both fields through early succession. [ABSTRACT FROM AUTHOR]