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Identification of factors explaining diversity in plant responses to industrial pollution is crucial for predicting fates of polluted ecosystems. Meta-analysis based on 203 publications demonstrated that plants growing near point polluters showed similar decreases in characters reflecting growth (-13.1%) and reproduction processes (-8.5%). In herbaceous plants, root growth was reduced, while aboveground biomass did not change, because the decrease in leaf size was compensated by an increase in leaf number. In contrast, woody plants demonstrated no changes in allometry and their growth was reduced to a greater extent than growth of herbaceous plants. Raunkiaer's classification of life forms appeared the best predictor of species' responses to pollution. Within woody plants, trees and shrubs, but not dwarf shrubs, showed strong decreases in growth and reproduction. Within herbaceous plants, significant growth reduction was observed only in annuals. Longevity of foliage or plant phylogeny did not explain variation in species' responses. Adverse effects of pollution were stronger in regions with higher temperature and precipitation, hinting that existing pollution loads may become more harmful for plants as climate changes. Relatively minor explanatory value of the characteristics of individual polluters removes one of the principal obstacles to accounting for the effects of pollution in vegetation models and allows extrapolation of the effects observed near point polluters to both regional and global scales. We conclude that losses in productivity of plant communities due to aerial pollution can be approximately estimated on the basis of the life form spectra and climate. Key words: biomass, climate, life forms, point polluters, plant species, resource allocation, temperature. L'identification des facteurs expliquant la diversite des reactions des plantes envers la pollution industrielle represente un enjeu critique pour predire le devenir des eecosystemes polluees. Une meta-analyse portant sur 203 publications demontre que les plantes poussant pres de pollutions ponctuelles montrent des diminutions similaires pour des domrees refletant la croissance (-13.1 %) et les processus de reproduction (-8.5 %). Chez les plantes herbaceees, on observe une diminution de la croissance racinaire, alors que la biomasse eepigeee ne change pas, parce que l'augmentation du nombre de feuilles compense la dimension de leur surface. Au contraire, les plantes ligneuses ne demontrent aucun changement dans l'alleilomeetrie et leur croissance montre une plus forte diminution que les plantes herbaceees. La classification des formes de vie des plantes semble constituer le meilleur moyen pour predire les reactions des plantes a la pollution. Chez les plantes ligneuses, seuls les arbres et les arbustes, mais pas les arbustes nains, montrent de fortes diminutions de croissance et de reproduction. Chez les plantes herbaceees, l'on observe de fortes diminutions de croissance seulement chez les plantes annuelles. La longevite du feuillage et la phylogeenie veegetale n'expliquent pas la variation dans les reactions des especes. Les effets de la pollution s'aggravent dans les regions chaudes a fortes precipitations, ce qui suggere que les charges polluantes en place pourraient devenir plus nuisibles pour les plantes avec les changements climatiques. La valeur explicative relativement faible des caracteristiques des polluants individuels elimine un des principaux obstacles pour rendre compte des effets de la pollution dans les modeles de vegetation, permettant d'extrapoler les effets observes pres des pollutions ponctuelles, aux echelles regionales et globales. Les auteurs concluent que l'on peut estimer approximativement les pertes de productivite des communautesveegetales dues a la pollution aerienne sur la base des spectres des formes de vie et du climat. Mots-cles: biomasse, climat, formes de vie, polluants ponctuels, especes vegetales, allocation des ressources, temperature. [Traduit par la Redaction], Introduction Vegetation shapes terrestrial ecosystems and serves several crucial functions in the biosphere. Due to both the economic and psychological importance of vegetation for mankind, deterioration of plant communities caused [...]

Riparian zones are hotspots of plant species richness in temperate and boreal biomes. The phenomenon is believed to be caused primarily by river-related processes, and upland influences on riparian zones have received relatively little attention. We investigated the importance of discharge of groundwater derived from uplands on riparian patterns in vascular plant species composition. We found that groundwater discharge areas in riparian zones were 36-209% more species rich than non-discharge areas, depending on spatial scale (1-50 m wide transects from annual high-water levels to summer low-water levels) and river (one free-flowing and one regulated). Higher nitrogen availability and less drought stress during low river stages are suggested as the major causes for the higher species diversity in discharge areas. Riparian zones lacking groundwater discharge lost more species following water-level regulation than did discharge areas. This indicates that groundwater discharge areas are more resistant to regulation because both individual plants and plant populations may grow larger in discharge areas. These results demonstrate that riparian zones are controlled by water and nutrient input from upland parts of catchments in ways that have been overlooked despite more than three decades of research into linkages between stream ecosystems and their valleys. Key words: groundwater discharge; nitrogen; pH; riparian zones; river regulation; soil chemistry; species richness; Sweden; vascular plants.

Vascular plants strongly control belowground environments in most ecosystems. Invasion by vascular plants in coastal wetlands, and by cordgrasses (Spartina spp.) in particular, are increasing in incidence globally, with dramatic ecosystem-level consequences. We examined the trophic consequences of invasion by a Spartina hybrid (S. alterniflora x S. foliosa) in San Francisco Bay (USA) by documenting differences in biomass and trophic structure of benthic communities between sediments invaded by Spartina and uninvaded sediments. We found the invaded system shifted from an algae-based to a detritus-based food web. We then tested for a relationship between diet and tolerance to invasion, hypothesizing that species that consume Spartina detritus are more likely to inhabit invaded sediments than those that consume surface algae. Infaunal diets were initially examined with natural abundance stable isotope analyses and application of mixing models, but these yielded an ambiguous picture of food sources. Therefore, we conducted isotopic enrichment experiments by providing [sup.15]N-labeled Spartina detritus both on and below the sediment surface in areas that either contained Spartina or were unvegetated. Capitellid and nereid polychaetes, and oligochaetes, groups shown to persist following Spartina invasion of San Francisco Bay tidal flats, took up [sup.15]N from labeled native and invasive Spartina detritus. In contrast, we found that amphipods, bivalves, and other taxa less tolerant to invasion consumed primarily surficial algae, based on [sup.13]C enrichment experiments. Habitat (Spartina vs. unvegetated patches) and location of detritus (on or within sediments) did not affect [sup.15]N uptake from detritus. Our investigations support a 'trophic shift' model for ecosystem response to wetland plant invasion and preview loss of key trophic support for fishes and migratory birds by shifting dominance to species not widely consumed by species at higher trophic levels. Key words: deposit feeder; detritus; ecosystem modification; food chain; infauna; isotope enrichment; plant invasion; salt marsh; San Francisco Bay; Spartina foliosa; Spartina hybrid; stable isotope analysis.

A simultaneous analysis of the species richness of vascular plants and their insect herbivores in semi-natural grasslands with varying grazing intensities was conducted. The results showed that grazing management leads to a decrease in the species richness of the grassland insects, with a notable increase in the species density and richness of vascular plants.

Research on forest plots in Tuscany, Italy, show that vascular plants are not an effective tool to maximize species richness of fungi. Woody plant species yielded better results, but not in all combinations of sites.

The surrogate method is found to be a valuable tool in selecting and planning conservation areas for vascular plants, particularly in megadiverse countries. More than 100 flora inventories throughout Mexico were used to assess the method.

1 We evaluated geographical and climate distributions of 57 vascular plant genera that have disjunct distributions primarily restricted to south-eastern Asia (EAS) and south-eastern North America (ENA). Because clades of each genus in the two regions are considered sister taxa, differences in ecological relationships between the regions reflect independent evolutionary responses to environmental factors and allow a test of ecological conservatism or parallelism. 2 The disjunct genera were found to be distributed in 270 grid cells, 163 in EAS and 107 in ENA, each with 3.75[degrees] extent in latitude and longitude. Individual disjunct genera occupied larger areas and latitudinal ranges in eastern Asia than in eastern North America, which parallels the larger area and latitudinal range of suitable climate in eastern Asia. 3 For all EAS-ENA disjunct genera taken together, the midpoint latitude, northernmost latitude, latitude range and area occupied were all significantly correlated between the two regions. For woody genera, only the correlation for midpoint latitude was significant, whereas for herbaceous genera, all except midpoint latitude were significant. 4 A twinspan analysis partitioned the grid cells into four distinctive groups based on presence or absence of the disjunct genera. Grid cells representing these groups in EAS and ENA remained clustered when plotted on axes defined by floristic ordination (non-metric multidimensional scaling) or climate variables (discriminant analysis), showing that the disjunct genera have similar floristic relationships to each other within regions and respond, to a large degree, in parallel to climate variables. 5 The lack of correlation in distribution variables among woody genera between the continents in part reflects the greater propensity of eastern Asian woody disjunct genera to extend southwards into subtropical and tropical latitudes. 6 Although the disjunct genera exhibit significant conservatism in geographical and climate distribution, reflecting their common evolutionary ancestry, differences between regions in geography, physiography and climate have also acted to diversify environmental relationships between continents.

Research on vascular plant, butterfly, and bird communities in the Greater Yellowstone Ecosystem suggests that surrogate taxon success is dependent on the technique utilized to evaluate surrogacy and the particular approach used for conservation planning. Coarse-filter conservation may be less dependent on species richness than on measures of community similarity.

Tropical forest birds are particularly sensitive to habitat perturbations compared with other taxa such as vascular plants. Extinctions of forest avi-fauna from the tropics and subtropics, lying largely between the Tropics of Cancer and Capricorn, have been reviewed in a study.

A study of the ecological effects of rock climbing on vascular plant, bryophyte, and lichen communities along the Niagara Escarpment in southern Ontario is presented. The results show that conservation plans should be modified to include policies regarding recreational rock climbing for lands containing exposed cliffs and the establishment of new climbing routes is banned in protested areas along the Niagara Escarpment.