Prediction of changes in the occurrence of forest herbs in hedgerow networks along a climate gradient in north-western Europe

Many herbaceous forest plant species are endangered and suffer from habitat loss and fragmentation, especially in agricultural landscapes. Hedgerow networks represent a forested habitat that may serve as a refuge for forest herbs, even though also hedges have recently been strongly reduced in number and size. It is yet disputed to which extent hedgerows offer a suitable environment for forest herbs and which environmental factors may affect the frequency of these species in hedgerows. To develop an effective conservation strategy for forest herbs in hedgerows on a larger spatial scale, we aimed to combine a set of ecological and life history traits for predicting the frequency of these species in a local data set. A literature data set was used to examine the regional differences in the species composition of forest herbs and environmental conditions in hedgerows along a climate gradient across north-western Europe. Contrary to our expectations, the chosen set of variables in combination had a lower ability of predicting the local frequency of forest herbs in hedgerows than the single variable light availability. An ordination of species lists in the literature data set showed pronounced regional differences in the species pools of forest herbs in hedgerows, the floristic gradient being closely related to climatic continentality. Hedgerows in more continental regions had lower proportions of chamaephytes and, according to an indicator species analysis, drier and less acid soils.     

Assessing ecological habitat structure from local to landscape scales using synthetic aperture radar

Ecological studies need accurate environmental data such as vegetation characterization, landscape structure and organization, to predict and explain the spatial distribution of biodiversity. Few ecological studies use remote sensing data to assess the biophysical or structural properties of vegetation to understand species distribution. To date, synthetic aperture radar (SAR) data have seldom been used for ecological applications. However, these sensors provide data allowing access to the inner structure of vegetation which is a key information in ecology. The objective of this article is to compare the predictive power of ecological habitat structure variables derived from a TerraSAR-X image, an aerial photograph and a SPOT-5 image for species distribution. The test was run with a hedgerow network in Brittany and assessed the spatial distribution of the forest ground carabid beetles which inhabit these hedgerows. The results confirmed that radar and optical images can be indifferently used to extract hedgerow network and derived landscape metrics (hedgerow density, network grain) useful to explain the spatial distribution of forest carabid beetles. In comparison with passive optical remotely sensed data, VHSR SAR images provide new data to characterize vegetation structure and more particularly hedgerow canopy cover, a variable known to explain the spatial distribution of carabid beetles in an agricultural landscape, but not yet quantified at a fine scale. The hedgerow canopy cover derived from the SAR image is a strong predictor of the abundance of forest carabid beetles at two scales i.e., a local scale and a landscape scale.     

Plant diversity in three types of hedgerows adjacent to cropfields

The farming landscape of eastern Canada is dotted with three main types of hedgerows: (1) natural woody, (2) planted woody and (3) herbaceous. The objective of this study was to compare the value of these habitats as a repository of plant biodiversity in agricultural areas of southern Quebec. The overall plant diversity was higher in natural hedgerows and they contained more plant species of conservation values than other hedgerow types. Plant species richness per quadrat was, however, higher in planted woody hedgerows, and together with the species composition, lead to the conclusion that planted hedgerows in their entirety consisted of an ecotone type of vegetation such as is found in field edges which usually support high plant diversity and productivity but where transient plant species predominate. Consequently, this study indicated that natural hedgerows fare better than planted hedgerows in terms of diversity of plants of conservation interest. In spite of that, planted woody hedgerows contained plant (and bird) species of some interest and should be favoured over more desolate herbaceous hedgerows. In areas where hedgerows were removed and are not re-establishing naturally, a mixture of deciduous trees and conifers should be encouraged in further windbreak planting programs so as to conciliate both the conservation and agronomic objectives. Furthermore, management practices should optimise the growth of establishing plants of conservation values.     

Hedgerows as habitat corridors for forest herbs in central New York, USA

1 Samples from 32 hedgerows ( c.  6 m wide, with full-grown trees) in central New York included 39 forest herb taxa, comprising nearly 70% of the forest herb taxa found in adjacent forest samples.
2 We sampled three types of hedgerow. Two types were attached to forest: remnant hedgerows ( n  = 14), and regenerated hedgerows ( n  =  11 ) that had grown up spontaneously between open fields in the last 50 years. There were no significant differences between remnant and regenerated hedgerows in the richness or abundance of forest herbs, presumably indicating colonization of regenerated hedgerows. Such colonization implies that hedgerows serve a corridor function.
3 The species composition of forest herbs in hedgerows attached to forest stands showed a strong affinity with that of the adjacent stand, both for remnant and regenerated hedgerows.
4 There was a distance effect within hedgerows. Richness of forest herbs and similarity of composition to forest declined with distance along the hedgerow from forest, implying colonization from the adjacent attached stand.
5 The third type of hedgerow sampled, isolated remnants ( n  = 7), was not lower in richness or abundance of forest herbs than hedgerows attached to forest.     

Woody plant composition of forest layers: the importance of environmental conditions and spatial configuration

The species–environment relationships for woody species may vary according to the forest layers considered. In fragmented forest, spatial configuration may also influence forest layer composition. We investigated the relationships between four forest layer compositions and environmental conditions, and spatial variables accounting for forest fragmentation, in 59 forest stands. Field and shrub layer compositions were mainly linked to environmental conditions, particularly to soil pH and slope aspect, while the upper layer compositions were principally correlated to the spatial configuration. The distance from the forest edge was correlated with all the forest layer compositions. Our results suggest that woody species respond to factors acting at different spatial and temporal scales, depending on the forest layer they belong to. The species–environment relationship seems to weaken from the lower to upper layer, the upper layer being more closely linked to the spatial configuration and probably to the past management. This study underlines the importance of taking spatial configuration in addition to environmental conditions into account when studying woody plant diversity for different forest layers in stands located in deciduous fragmented forests. Moreover, stand history seems to have a lasting effect on woody plant composition, particularly for the tree layer.     

Hedgerows support rich communities of harvestmen (Opiliones) in upland agricultural landscape

Hedgerows play important roles in agricultural landscapes and they increase biodiversity by providing habitat refugia for species sensitive to agricultural disturbance. We have studied the characteristics of the communities of harvestmen (Opiliones) inhabiting hedgerows. Harvestmen are terrestrial arachnids associated with soil surface and subsurface and sensitive to land-use and disturbance. We were specifically interested in quantifying how hedgerow characteristics (e.g., elevation, length, width, connectivity, and plant diversity) affect harvestman diversity and community composition. We expected harvestman diversity and community composition to be positively related to both hedgerow size (area, length, width) and biological attributes of hedgerows (e.g., connectivity, plant community diversity). We surveyed hedgerow characteristics and harvestman communities of 20 hedgerows in an upland agricultural landscape in the Western Carpathians. Hedgerow characteristics were measured in the field or derived from GIS layers and we used correlation and ordination methods to relate them to harvestman community metrics. We found surprisingly high taxonomic richness of harvestmen within the studied hedgerows (15 species). Importantly, the Shannon index of harvestman communities was positively related to hedgerow length and hedgerow tree layer species richness and diversity. Harvestman community composition varied with hedgerow area and width. Despite their small total area, hedgerows represented an important habitat for diverse harvestman communities and hedgerow attributes such as size and tree diversity significantly affected the composition and the Shannon index of harvestman communities. Thus, greater lengths and widths of hedgerows can provide habitats for a higher Shannon index of harvestman communities, within surrounding agricultural landscapes.     

Diversity of Anurans Across Agricultural Ponds in Argentina

We examined the anuran diversity of 31 ponds (30 located on the border of soybean cropland and one within a protected forest) in mid-western Entre Ríos Province (Argentina). Moreover, each species found was characterised with respect to its vertical location. Using principal component (PCA) and canonical correspondence analyses (CCA) we quantified associations between species diversity and habitat and spatial variables. A total of 21 anuran species belonging to four families (Microhylidae, Bufonidae, Leptodactylidae and Hylidae) were detected in ponds surrounded by soybean croplands. PCA generated three principal components, which together explained variation in anuran diversity across the agricultural ponds and control site. Negative values of PC-1 described the smaller ponds with narrower hedgerow and monospecific shore vegetation. PC-2 had high loading on pond depth, and PC-3 had negative loading on air temperature. CCA showed a very strong association between the two data sets. We found all guilds related with pond area. Indeed, we found that arboreal species were recorded in large ponds with higher values of shore vegetation index and presence of wider hedgerow. Moreover, a higher number of terrestrial species was found to relate to large pond areas and greater shore vegetation diversity. Finally, aquatic species were related to pond area, shore vegetation index and depth. Anuran diversity across agricultural ponds of mid-western Entre Ríos Province can be affected by local habitat factors such as reduction in pond size and depth, shore vegetation richness, width of hedgerow and air temperatures. Management of anurans to reverse recent declines will require defining high-quality habitat for individual species or group of species, followed by efforts to retain or restore these aquatic habitat. The maintenance of shore vegetation of ponds and hedgerows may increases the number of species and diversity of anurans within agricultural landscapes.     

Forest vascular plants as indicators of plant species richness: A data analysis of a flora atlas from northwestern Germany

Abstract

Our study had the objective to examine whether the number of forest vascular plants in a forest-poor region may be indicative of total plant species richness and of the number of threatened plant species. We also related forest plant species richness to geological and soil variables. The analysis was based on a regional flora atlas from the Weser-Elbe region in northwestern Germany including incidence data of species in a total of 1109 grid cells (each ca. 2.8 × 2.8 km²). All taxa were classified either as forest or non-forest species. Total species richness in the grid cells ranged from 65 to 597, with a mean value of 308. The number of forest species varied between 20 and 309 (mean 176). Grid cells with or without particular geological units differed in total and forest species richness, with those containing peatland and marshland being particularly species-poor. Indicator value analysis showed that both total and forest species richness in the grid cells were related to soil acidity and nitrogen in a hump-backed manner, with the highest number of species found at moderately low values for nitrogen and at intermediate values of pH. Forest species richness was highly positively correlated with the number of non-forest species and threatened non-forest species. Indicators for high species richness were primarily those species that are confined to closed semi-natural forests with a varied topography and relatively base- and nutrient-rich soils. Grid cells including historically ancient forest exhibited a higher species richness than grid cells lacking ancient forest, indicating the importance of a long habitat continuity for a high phytodiversity. The “habitat coincidence” of high species richness is best explained by similar responses of forest species and species of other habitats to the main environmental gradients. It is suggested that the regional patterns found for the Weser-Elbe region can be transferred also to other forest-poor regions in Central Europe.     

Bee Preference for Native versus Exotic Plants in Restored Agricultural Hedgerows

Habitat restoration to promote wild pollinator populations is becoming increasingly common in agricultural lands. Yet, little is known about how wild bees, globally the most important wild pollinators, use resources in restored habitats. We compared bee use of native and exotic plants in two types of restored native plant hedgerows: mature hedgerows (>10 years from establishment) designed for natural enemy enhancement and new hedgerows (≤2 years from establishment) designed to enhance bee populations. Bees were collected from flowers using timed aerial netting and flowering plant cover was estimated by species using cover classes. At mature hedgerow sites, wild bee abundance, richness, and diversity were greater on native plants than exotic plants. At new sites, where native plants were small and had limited floral display, abundance of bees was greater on native plants than exotic plants; but, controlling for floral cover, there was no difference in bee diversity and richness between the two plant types. At both mature and new hedgerows, wild bees preferred to forage from native plants than exotic plants. Honey bees, which were from managed colonies, also preferred native plants at mature hedgerow sites but exhibited no preference at new sites. Our study shows that wild bees, and managed bees in some cases, prefer to forage on native plants in hedgerows over co‐occurring weedy, exotic plants. Semi‐quantitative ranking identified which native plants were most preferred. Hedgerow restoration with native plants may help enhance wild bee abundance and diversity, and maintain honey bee health, in agricultural areas.     

Hedgerows as an environment for forest plants: a comparative case study of five species

Many areas in Europe are dominated by agricultural land use, and as a consequence, many typical forest plant species suffer from habitat loss and fragmentation. Hedgerows, one of the common elements of rural landscapes, have been considered as potential refuges for these species. The main objective of this study was to examine whether forests and hedgerows differ in environmental conditions, and whether important life-history attributes of the populations differ between the two habitat types. We selected five species commonly found in the region in both forests and hedgerows (Adoxa moschatellina, Anemone nemorosa, Circaea lutetiana, Polygonatum multiflorum and Stellaria holostea), and sampled data on 10 populations of each species in each habitat type, including measurements of light and various soil factors. Hedgerows had higher relative light availability and tended to have higher soil nutrient contents and lower soil water values than forests. The comparison of plant performance values between habitat types did not show consistent patterns across species. Anemone and Polygonatum performed equally well in hedgerows and forests, whereas Stellaria appeared to have a higher fitness in hedgerows. In contrast, Circaea showed a higher reproduction under forest conditions. For Adoxa, the results were somewhat contradictory: whereas the reproductive output of this species was higher in forests, population density was higher in hedgerows. The abiotic factors most closely related to the performance values were relative light and soil water availability. The majority of plant performance values did not differ between hedgerows and forests. We therefore conclude that the tested forest species are capable of growing also in hedgerows and will survive equally well in forest and its “surrogate” habitat.     

Hedgerows as corridors for woodland plants: a test on the Po Plain,northern Italy

The use of hedgerows as corridors for forest vascular species has been widely studied, but only in humid oceanic and continental climates; no replicated trials have ever been performed on corridor function. Given these premises, a study was done on the eastern Po Plain, in a transition area between the Temperate (Eurosiberian) and Mediterranean climatic zones, adopting the same sample shape and dimensions as a North-American study [Corbit et al. (1999) J Ecol 87:220–232]. The following research questions were posed: (1) how common are forest species in hedgerows? (2) do origin, isolation, distance from source, width and adjacent land-use factors correlate with the frequency of forest species? (3) are hedgerows corridors for forest species? To address these, three functional types of hedgerows, identified by comparing old aerial-photos, were sampled: remnant attached (n = 12) and remnant isolated (n = 6) with respect to the nearest woodland and regenerated attached (n = 4). If wooded patches were a source for hedgerows, then regenerated hedgerows should be more similar to an adjacent woodland than an isolated remnant. A 900 m² circular plot in woodlands and an adjacent 90-m transect along hedgerows were sampled for the presence and cover of all plant species, then 39 woodland taxa were selected. Significant differences between the three hedgerow types emerged in forest species richness, but not in cover. The forest species composition in both remnant and regenerated attached hedgerows showed a strong affinity with the adjacent stand, implying a dispersal process from woodland (source) to regenerated hedgerows (sink). A distance effect on forest species distribution clearly linked to a corridor function was found only in regenerated hedgerows, while in the remnant attached ones, even with a composition similar to that of the nearest woodland source, other additional factors cannot be ignored to explain the fine scale distribution of forest species. The cover of the most common ant-dispersed species showed a similar distance effect while vertebrate-dispersed ones did not show any significant trend with distance from woodlands. Habitat suitability for forest species was affected by width, especially in hedges wider than 12 m, but not by adjacent land use.     

Effects of hedgerows on bats and bush crickets at different spatial scales

Biodiversity is threatened by the loss and fragmentation of habitats. The role of hedgerows in maintaining biodiversity is well established, but few studies have addressed the importance for biodiversity of the intrinsic characteristics of hedgerows and the quality of hedgerow networks along a spatial scale. We examined three quality indices providing information at different territorial levels: density in the landscape, structural diversity and wood production. We performed an acoustic survey in a grassland to estimate the species abundance and community composition of bats (9 taxa) and bush crickets (11 species). Using an approach based on species and traits, we assessed how hedgerow quality influenced the activity of these taxa at different spatial scales (from 50 to 1000 m) and focused on three types of traits: bush cricket mobility ability, bat foraging strategy and habitat specialization. In general, our results showed the importance of hedgerow quality for bats and bush crickets, but the strength of the association between taxa and hedgerows varied substantially among the species and the spatial scales. Although it depends on the taxa, the production, density and structural diversity of hedgerows each had an overall positive effect. Our results suggested that these effects were generally more important at large scales. The scale effect of the production index is the best predictor of activity for bat and bush cricket taxa and traits. Our results showed the importance of hedgerow quality for the ecology of bat and bush cricket communities and could be used to improve conservation management.     

Morphophysiologic traits of spruce trees in conditions of Izhevsk

Data on the condition of Picea genus (spruce) representatives in an urban environment have been analyzed. The viability under different environmental conditions and stand types is evaluated. The relative viability of forest stands is evaluated. Morphogenic traits of conifers are examined for the annual increment development. The photosynthetic pigments dynamics is tracked for two coniferous plants across various forest types, including park forests, roadside hedgerows, and plantings in the residential area. The specific responses of pigment system to the urban environment have been revealed for the two coniferous plant species. We have found an increased concentration of carotinoids and higher resilience of blue spruce (Picea pungens Engelm.) in an urban environment.     

The use of hedgerows as flight paths by moths in intensive farmland landscapes

Linear boundary features such as hedgerows are important habitats for invertebrates in agricultural landscapes. Such features can provide shelter, larval food plants and nectar resources. UK butterflies are known to rely on such features, however their use by moths is understudied. With moth species suffering from significant declines, research into their ecology is important. This research aimed to determine whether UK moth species are using hedgerows as flight paths in intensive farmland. The directional movements of moths were recorded along hedgerows at 1, 5 and 10 m from the hedgerow face. The majority of moths recorded within the study were observed at 1 m from the hedgerow (68 %), and of these individuals, 69 % were moving parallel in relation to the hedge. At further distances, the proportion of parallel movements was reduced. These results suggest that hedgerows may be providing sheltered corridors for flying insects in farmland landscapes, as well as likely providing food plants and nectar resources, emphasising the importance of resource-based approaches to conservation for Lepidoptera.     

The value of woody hedgerows for moth diversity on organic and conventional farms

Habitat destruction and degradation are important drivers of biodiversity loss within agro-ecosystems. However, little is known about the effect of farming practices and the value of woody hedgerows on Lepidoptera in North America. The purpose of this work was to study moth diversity in woody hedgerows and croplands of organic and conventional farms. In addition, the influence of vegetation composition and abiotic variables on species richness, abundance, and composition was examined. Moths were sampled with light traps during six weeks in the summer of 2001. Vegetation data and abiotic variables were obtained for all sites. In total, 26,020 individuals from 12 families and 408 species were captured. Most species were uncommon. Only 35 species included >100 individuals while for 71% of species <10 individuals were found. The Noctuidae represented 221 species and 85% of all individuals captured. Woody hedgerows harbored more species and in greater number than croplands. There was no significant difference in moth diversity between organic and conventional farms, except that the Notodontidae were significantly more species rich in organic than in conventional sites. Results show that species richness, abundance, and composition were greatly influenced by habitat types (hedgerow versus crop field) and abiotic variables (minimum temperature which was correlated to moon illumination, rainfall, and cloud cover). Moth species composition was significantly correlated to vegetation composition. This study broadens our understanding of the factors driving moth diversity and expands our knowledge of their geographic range. The maintenance of noncrop habitats such as woody hedgerows within agro-ecosystems seems paramount to preserving the biodiversity and abundance of many organisms, including moths.     

The relative roles of environment and history as controls of tree species composition and richness in Europe

Aim This study investigates the determinants of European‐scale patterns in tree species composition and richness, addressing the following questions: (1) What is the relative importance of environment and history? History refers to lasting effects of past large‐scale events and time‐dependent cumulative effects of ongoing processes, notably dispersal limited range dynamics. (2) Among the environmental determinants, what is the relative importance of climate, soils, and forest cover? (3) Do the answers to questions 1 and 2 differ between conifers and Fagales, the two major monophyletic groups of European trees? Location The study area comprises most of Europe (34° N–72° N and 11° W–32° E). Methods Atlas data on native distributions of 54 large tree species at 50 × 50 km resolution were linked with climatic, edaphic, and forest cover maps in a geographical information system. Unconstrained (principal components analysis using Hellinger distance transformation and detrended correspondence analysis) and constrained ordinations (redundancy analysis using Hellinger distance transformation and canonical correspondence analysis) and multiple linear regressions were used to investigate the determinants of species composition and species richness, respectively. History is expected to leave its mark as broad spatial patterns and was represented by the nine spatial terms of a cubic trend surface polynomial. Results The main floristic pattern identified by all ordinations was a latitude‐temperature gradient, while the lower axes corresponded mostly to spatial variables. Partitioning the floristic variation using constrained ordinations showed the mixed spatial‐environmental and pure spatial fractions to be much greater than the pure environmental fraction. Biplots, forward variable selection, and partial analyses all suggested climatic variables as more important floristic determinants than forest cover or soil variables. Tree species richness peaked in the mountainous regions of East‐Central and Southern Europe, except the Far West. Variation partitioning of species richness found the mixed spatial‐environmental and pure spatial fractions to be much greater than the pure environmental fraction for all species combined and Fagales, but not for conifers. The scaled regression coefficients indicated climate as a stronger determinant of richness than soils or forest cover. While the dominant patterns were similar for conifers and Fagales, conifers exhibited less predictable patterns overall, a smaller pure spatial variation fraction relative to pure environmental fraction, and a greater relative importance of climate; all differences being more pronounced for species richness than for species composition. Main conclusions The analyses suggest that history is at least as important as current environment in controlling species composition and richness of European trees, with the exception of conifer species richness. Strong support for interpreting the spatial patterns as outcomes of historical processes, notably dispersal limitation, came from the observation that many European tree species naturalize extensively outside their native ranges. Furthermore, it was confirmed that climate predominates among environmental determinants of distribution and diversity patterns at large spatial scales. Finally, the particular patterns exhibited by conifers probably reflect greater environmental specialization and greater human impact. These findings warn against expecting the European tree flora to be able track fast future climate changes on its own.     

Effects of woody plant species richness on mammal species richness in southern Africa

Aim To determine the relationship between the species richness of woody plants and that of mammals after accounting for the effect of environmental variables. Location Southern Africa, including Namibia, South Africa, Lesotho, Swaziland, Botswana, Zimbabwe, and part of Mozambique. Methods We used a comprehensive dataset including the species richness of mammals and of woody plants and environmental variables for 118 quadrats (each of 25,000 km²) across southern Africa, and used structural equation models (SEMs) and spatial regressions to examine the relationship between the species richness of woody plants and of mammal trophic guilds (herbivores, insectivores, carni/omnivores) and habitat guilds (aquatic/fossorial, ground‐living, climbers, aerial), after controlling for environment. We compared the results of SEMs with those of single‐predictor regressions (without controlling for environment) and of spatial regressions (controlling for both environment and residual spatial autocorrelation). Results The geographical variation of mammal species richness in southern Africa was strongly and positively related to that of woody plant species richness, and this relationship held for most mammal guilds even when the influence of environment and spatial autocorrelation had been accounted for. However, the effect of woody plant species richness on the richness of aquatic/fossorial species almost disappeared after controlling for environment, suggesting that the congruence in species richness patterns between these two groups results from similar responses to the same environmental variables. For many mammal guilds, the relative role of environmental predictors as measured by standardized partial regression coefficients changed depending on whether non‐spatial single‐predictor regressions, non‐spatial SEMs, or spatial regressions were used. Main conclusions Woody plants are important determinants of the species richness of most mammal guilds in southern Africa, even when controlling for environment and residual spatial autocorrelation. Environmental correlates with animal species richness as measured by simple correlations or single‐predictor regressions might not always reflect direct effects; they might, at least to some degree, result from indirect effects via woody plants. Interpretations of the strength of the effect of environmental variables on mammal species richness in southern Africa depend largely on whether spatial or non‐spatial models are used. We therefore stress the need for caution when interpreting environmental ‘effects’ on broad‐scale patterns of species richness if spatial and non‐spatial methods yield contrasting results.     

Pollination and reproduction of a self-incompatible forest herb in hedgerow corridors and forest patches

Habitat-corridors are assumed to counteract the negative impacts of habitat loss and fragmentation, but their efficiency in doing so depends on the maintenance of ecological processes in corridor conditions. For plants dispersing in linear habitats, one of these critical processes is the maintenance of adequate pollen transfer to insure seed production within the corridor. This study focuses on a common, self-incompatible forest herb, Trillium grandiflorum, to assess plant–pollinator interactions and the influence of spatial processes on plant reproduction in hedgerow corridors compared to forests. First, using pollen supplementation experiments over 2 years, we quantified the extent of pollen limitation in both habitats, testing the prediction of greater limitation in small hedgerow populations than in forests. While pollen limitation of fruit and seed set was common, its magnitude did not differ between habitats. Variations among sites, however, suggested an influence of landscape context on pollination services. Second, we examined the effect of isolation on plant reproduction by monitoring fruit and seed production, as well as pollinator activity and assemblage, in small flower arrays transplanted in hedgerows at increasing distances from forest and from each other. We detected no difference in the proportion of flowers setting fruit or in pollinator activity with isolation, but we observed some differences in pollinator assemblages. Seed set, on the other hand, declined significantly with increasing isolation in the second year of the study, but not in the first year, suggesting altered pollen transfer with distance. Overall, plants in hedgerow corridors and forests benefited from similar pollination services. In this system, plant–pollinator interactions and reproduction seem to be influenced more by variations in resource distribution over years and landscapes than by local habitat conditions. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Ferns and Melastomataceae as indicators of vascular plant composition in rain forests of Colombian Amazonia

In a case-study from Colombian Amazonia, species information from ferns and Melastomataceae was used to explain the compositional patterns of other vascular plant species in 40 widely distributed 0.1-ha plots. Canonical correspondence analysis was applied to regress vascular plant species composition in the forests against information from these two indicator groups (summarized as axes of principal coordinate analyses), together with that from soils, landscape, and the spatial sampling design. In total, 53,941 individuals of 2480 vascular plant species were recorded. Of these, 17,473 individuals and 132 species were from ferns and Melastomataceae. In 19 well-drained upland (tierra firme) plots 19,622 vascular plant individuals and 1716 species were found, with 3793 plants and 91 species from ferns and Melastomataceae. In both the set of all landscapes and the subset of tierra firme forests the principal PCoA axes of the two indicator groups were highly related to the main patterns of forest species composition. In principle, therefore, ferns and Melastomataceae can be used to detect and forecast changes in the forest composition of the study area. However, evidence was not obtained that ferns and Melastomataceae show more potential to predict the main patterns in species composition of forests than soil, landscape, and spatial variables. The partioning of the total variation in forest composition showed that the correlation of ferns and Melastomataceae with other forest plants was quite independent from that of soil, landscape, and space. Direct effects of ferns and Melastomataceae on other plants might be obtained from experimental studies of between-plant interactions, concentrating on the seedling or juvenile stages of trees and lianas, both above-ground as well as in the rooting environment.     

山西太岳山脱皮榆群落的生态梯度分析及环境解释

为了解释山西太岳山脱皮榆(Ulmus lamellosa)群落中物种的分布情况与该群落环境因子之间的相互关系,采用TWINSPAN数量分类和典范对应分析(CCA)与环境因子的变量分离进行讨论。结果表明,TWINSPAN将60个调查样方划分为7种群丛类型,体现了该脱皮榆群落主要以乔木脱皮榆和草本披针叶苔草(Carex lanceolata)为优势种。7种群丛类型与CCA排序结果一致,CCA排序第1轴主要体现了坡位和海拔;坡向与第2排序轴存在显著相关性。Monte Carlo检验结果表明,影响脱皮榆群落物种分布最主要的环境因子是海拔。在环境分离变量解释方面,环境因子解释了39.60%,空间因子解释了7.95%,空间因子与环境因子交互作用解释部分占10.89%。而其中不能解释的部分占41.56%。在该研究区,海拔对植物的分布有较好的解释力,其次是坡位和坡向。