Selection of secondary growth areas by vervet monkeys (Cercopithecus aethiops)

Habitat selection by a group of vervet monkeys (Cercopithecus aethiops) living on the savanna peninsula of St. Kitts was investigated by the intensive sampling of 12 transects. The vervets exhibited nonrandom use of habitats. Examination of 20 ecological variables in each of the habitat types revealed that the vervets preferentially used areas of secondary growth characterized by high density and diversity of tall food plants. It is suggested that the preferential use of secondary growth habitat can be attributed to the fact that these areas have high levels of plant productivity and that they have a large proportion of their productivity available for consumption.     

Rodent Diversity and Land Use in Montebello,Chiapas, Mexico

We analyzed the abundance and diversity of Heteromyid and Murid rodents in the Lagos de Montebello National Park and adjacent areas, Chiapas, Mexico. We sampled three habitat types with different degrees of disturbance: pine-oak-liquidambar forest, ecotone and crop farming lands. Habitat types were defined considering characteristics such as heterogeneity, structural complexity and arboreal cover. We obtained ancillary habitat data considered important for small mammal requirements. Data on rodent communities were obtained by capture-mark-recapture between February and October 1996. We made 410 captures in 3820 trap-nights effort. Ten species were recorded, including one endemic with restricted distribution in Chiapas. Mouse diversity in the forest was significantly higher than within the farm lands. A Kendall correlation analysis showed positive relationship between rodent community species richness and habitat heterogeneity. Diversity of rodents was associated with the habitat complexity and structural elements, and negatively correlated with farming intensity. We found a high beta diversity and low similarity of the rodent communities in the three different habitats. Community composition strongly changed from the forest through the ecotone into the farm lands, with five species gained and seven species lost. The highest species richness was found in the ecotone; however, it showed a strong dominance of a single species that can convert into a plague of crops, and relatively low abundance of the other species. The pine-oak-liquidambar forest had the highest diversity indices, sheltering a particular rodent community within the study area, it therefore probably has the most important role in the conservation of the local biodiversity.     

Habitat quality and range use of white-headed langurs in Fusui, China

The socioecology of white-headed langurs (Trachypithecus leucocephalus) was studied in Fusui Precious Animal Reserve, Guangxi, China, in 1997/1998. Habitat quality was classified according to the level of human disturbance. Plant species diversity increased with habitat quality. Important foods for the langurs occurred more in high-quality habitat. Home range size varied from 28 to 48 ha, and the home range area per individual decreased as habitat quality increased. Small polygynous langur groups had poorly defended ranges, but large groups defended their ranges intensively. Only harem males were involved in group defence, apparently competing for females by defending their habitat. High-quality habitat was more attractive to females; accordingly, group size increased significantly with habitat quality.     

Population Characteristics of Howlers: Ecological Conditions or Group History

We examined the relative importance of ecological parameters—habitat productivity and seasonality—and group history—episodic predation, disease, and sudden habitat deterioration—to explain variation in the density and group structure of howlers (Alouatta spp.). We use data from a census of Guanacaste National Park, Costa Rica, and a literature review characterizing 80 howler populations. In Guanacaste National Park both habitat type and degree of protection affect howler density and group structure. Howlers were found at the highest density and in the largest groups in areas of semievergreen forest, which ecological sampling indicates have the most consistent level of food production. Differences in density between the sector of the park that first received protected status and more recently protected areas may be due partially to the degree of protection the areas received. We test the prediction that howler density and group structure would be influenced by habitat productivity as indexed by rainfall. Average group size and sex ratios differ among species, but female-to-immature ratios do not. Considering all censuses at one site to be independent, there are significant interspecific differences in density, with Alouatta pigra occurring at lower densities than the other species. In spite of such variability, there is no relationship between annual rainfall and howler density, and rainfall had a variable effect on group size depending on the level of independence that was considered. While such ecological comparisons are unrefined, e.g., rainfall must be used as a surrogate for habitat production, the fact that so few relationships were documented suggests that factors other than the ecological factors considered here are responsible for the observed differences in population characteristics. We suggest that much of the variability in howler population characteristics is related to events occurring in the recent history of the groups, such as habitat alteration, hunting, food tree crop failure, and disease.     

Effects of habitat complexity on ant assemblages

We investigated responses of ant communities to habitat complexity, with the aim of assessing complexity as a useful surrogate for ant species diversity. We used pitfall traps to sample ants at twenty-eight sites, fourteen each of low and high habitat complexity, spread over ca 12 km in Sydney sandstone ridge-top woodland in Australia. Ant species richness was higher in low complexity areas, and negatively associated with ground herb cover, tree canopy cover, soil moisture and leaf litter. Ant community composition was affected by habitat complexity, with morphospecies from the genera Monomorium, Rhytidoponera and Meranoplus being the most significant contributors to compositional differences. Functional group responses to anthropogenic disturbance may be facilitated by local changes in habitat complexity. Habitat complexity, measured as a function of differences in multiple strata in forests, may be of great worth as a surrogate for the diversity of a range of arthropod groups including ants.     

Forest Fragment and Breeding Habitat Characteristics Explain Frog Diversity and Abundance in Singapore

Habitat loss and fragmentation can have severe negative and irreversible effects on biodiversity. We investigated the effects of forest fragmentation on frog diversity in Singapore because of its high rates of deforestation and the demonstration that frogs are some of the most sensitive species to habitat degradation. We surveyed frog species in 12 forest fragments varying from 11 to 935 ha. We compared differences in species richness, abundance, and Shannon's index in relation to forest fragment size, connectivity (distance between fragments), and breeding habitat heterogeneity. A total of 20 species from 12 genera and five families were encountered in 12 fragments. Larger fragments and those closer to larger fragments had higher species richness. Abundance, however, was not correlated with forest area or connectivity, but we found fewer individual frogs in the larger fragments. We also found that breeding habitat heterogeneity best explained frog species diversity and abundance in forest fragments. Fragments with a high diversity of breeding habitats had more species. We found no evidence to suggest that abundance and diversity are strongly correlated, particularly in disturbed areas, but that breeding habitat heterogeneity is an under-appreciated factor that should be considered when prioritizing areas for anuran conservation. Enriching breeding habitat heterogeneity, creating corridors between fragments, and reforesting degraded areas are some of the most beneficial strategies for preserving urban frog biodiversity.     

Plant functional group composition and large‐scale species richness in European agricultural landscapes

Question: Which are the plant functional groups responding most clearly to agricultural disturbances? Which are the relative roles of habitat availability, landscape configuration and agricultural land use intensity in affecting the functional composition and diversity of vascular plants in agricultural landscapes? Location: 25 agricultural landscape areas in seven European countries. Methods: We examined the plant species richness and abundance in 4 km × 4 km landscape study sites. The plant functional group classification was derived from the BIOLFLOR database. Factorial decomposition of functional groups was applied. Results: Natural habitat availability and low land use intensity supported the abundance and richness of perennials, sedges, pteridophytes and high nature quality indicator species. The abundance of clonal species, C and S strategists was also correlated with habitat area. An increasing density of field edges explained a decrease in richness of high nature quality species and an increase in richness of annual graminoids. Intensive agriculture enhanced the richness of annuals and low nature quality species. Conclusions: Habitat patch availability and habitat quality are the main drivers of functional group composition and plant species richness in European agricultural landscapes. Linear elements do not compensate for the loss of habitats, as they mostly support disturbance tolerant generalist species. In order to conserve vascular plant species diversity in agricultural landscapes, the protection and enlargement of existing patches of (semi‐) natural habitats appears to be more effective than relying on the rescue effect of linear elements. This should be done in combination with appropriate agricultural management techniques to limit the effect of agrochemicals to the fields.     

Benefits of habitat restoration to small mammal diversity and abundance in a pastoral agricultural landscape in mid-Wales

Changes in agricultural practice are predicted across the UK following agricultural reform driven by government policy. The suitability of agri-environment schemes for many species is currently debated because limited quantitative data are collected. In order to understand the changes to biodiversity due to agri-environment schemes, there is a need for studies to not just compare biodiversity and species composition in and out of agri-environment areas, but to factor in the influence of temporal habitat changes. In this study, we investigate the suitability of an agri-environment initiative to support and enhance a small mammal fauna among pastoral hill farms in mid-Wales. Grazed and ungrazed woodlands, riparian habitats, and broadleaf plantations, were compared for small mammal abundance and diversity following a trapping study. Mammal diversity was similar across habitats, though abundance varied significantly. A principle component analysis identified that mammal abundance clustered into three main habitat groups separated by seral stage (early, mid, late). No relationship between mammal abundance and stock grazing was found. A canonical correspondence analysis confirmed that vegetation structure was important in explaining the distribution of captures of mammal species across the landscape. The results for habitat type, and habitat context, suggest that a mix of vegetation seral stages, reflecting a varied vegetation structure, is important to maintain small mammal diversity and abundance across the study area. Heterogeneity in structural diversity at the landscape scale is important to maintain a variety of ground-dwelling mammal species, and particularly because trends in countryside surveys show that woodlands are skewed towards late seral stages. Habitat heterogeneity can be maintained because the hill farms neighbour each other, and the farmers co-operate as a group to manage the landscape. Habitat diversity is therefore possible. These results help us to advocate, and anticipate, the benefits of groups of farms within a landscape.     

Habitat complementarity and butterfly traits are essential considerations when mitigating the effects of exotic plantation forestry

Habitat loss threatens insect diversity globally. However, complementary vegetation types in remaining habitat increases opportunities for species survival. We assess the extent to which indigenous forest patches moderate the impact of exotic commercial afforestation on grassland butterflies. Butterflies were sampled in grassland along uncorrelated gradients of landscape-scale indigenous forest and plantation cover, while controlling for variation in local vegetation composition. We separately assessed responses by butterfly groups differing in habitat preference, larval diet, and mobility. There was no effect of landscape- or local-scale variables on species richness, but there was a strong interactive effect of forest and plantation cover on butterfly assemblage structure. The effect varied according to species traits. When forest cover was high, assemblages did not differ at different levels of plantation cover. However, plantation cover significantly influenced assemblage structure when forest cover was low. Grassland with limited forest cover in the protected area supported unique assemblages with high frequency of less mobile, specialized species with herbaceous larval host plants, whereas grassland with low forest cover near plantations had a prevalence of mobile, generalist species. A positive association between forest cover and butterflies with woody larval host plants suggests that indigenous forest patches improved the suitability of fragmented grassland for a subset of butterflies, emphasising the value of natural heterogeneity in transformed areas. However, certain butterfly traits associated with large, open grassland were under-represented in grassland between plantations, underscoring the importance of open areas in the broader landscape to conserve the full diversity of species.

     

Habitat degradation,topography and rainfall variability interact to determine seed distribution and recruitment in a sand dune grassland

Question: Understanding the mechanisms underlying how habitat degradation, topography and rainfall variability interactively affect seed distribution and seedling recruitment is crucial for explaining plant community patterns and dynamics. Interactions between these major factors were studied together in a semiarid sand dune grassland. Location: Eastern Inner Mongolia, China. Methods: The study system used four sites of fixed, semifixed, semishifting and shifting sand dune grasslands, representing a gradient of habitat degradation. We investigated the density of germinable seeds deposited in the top 5 cm of soil and in situ seedling emergence (number of seedlings emerging early in the growing season) and establishment (number of plants recruited at the end of the growing season) at three topographic positions (dune top, windward and leeward sides) within each site over 2 years that differed in rainfall. Habitat characteristics (i.e. vegetation cover, plant species composition and diversity, soil moisture and nutrient availability and soil erodibility) of the four sites were also measured. Results: Habitat degradation (i.e. decreased vegetation cover and enhanced wind erosion rate) significantly reduced the size of the germinable soil seed bank. On average, germinable seed number from the high‐vegetation cover fixed dune was 36‐fold larger than the low‐vegetation cover shifting dune, and eight‐ and two‐fold larger, respectively, than the semishifting and semifixed dunes with intermediate vegetation cover. We observed within‐habitat variability in seed distribution, but among‐topographic position variation differed among habitats. Seedling recruitment showed large between‐year, and among‐ and within‐habitat variability, but these variations varied significantly depending on the response variables evaluated (i.e. initial seedling density, final plant density, emergence rate and recruitment rate). Path analysis revealed complex density‐dependent positive and negative, direct and indirect effects of germinable seed density and initial seedling density on recruitment, but the relative importance of these density‐dependent effects varied depending on habitat type and rainfall availability. Conclusion: Our results suggest that habitat degradation, microtopography and rainfall availability interact in shaping sand dune seed bank and plant community recruitment patterns and dynamics. Their effects were mainly mediated through changes in both the biotic and abiotic environment during the process of habitat deterioration.     

Environmental factors affecting patterns of distribution and co‐occurrence of two competing raptor species

Habitat selection is a complex process, that is affected by several factors, including habitat characteristics, environmental conditions, and both intra‐ and interspecific interactions. We analysed habitat preferences of two top avian predators, Peregrine Falcon Falco peregrinus, a medium‐sized diurnal raptor, and Eagle Owl Bubo bubo, a large nocturnal raptor. These two species are known to compete for preferred nest‐sites, and proximity to cliffs with Eagle Owls may reduce Peregrine breeding output through predation of young Falcons. We investigated the environmental factors affecting occurrence and coexistence of the two species and the potential role of habitat suitability in favouring co‐occurrence in 3519 km² of the central pre‐Alps of Italy, where the two species breed on cliffs and sometimes co‐occur on the same cliff. Peregrines settled on long, steep and favourably orientated cliffs in woodland landscapes close to urban areas. Eagle Owls settled on topographically similar cliffs, but in lower rainfall areas compared with cliffs occupied by Peregrines and cliffs unoccupied by either species. Sites where the two species co‐occurred were characterized by more horizontally extended cliffs compared with sites of exclusive occurrence of each species. An analysis of relative habitat suitability revealed that sites where the two species co‐occurred had the highest predicted probability of occupancy for both species, suggesting that those sites should be regarded as high‐quality sites. Breeding productivity of Eagle Owls was negatively affected by the co‐occurrence of Peregrines, whereas the effect of Eagle Owl proximity on Peregrine productivity varied according to cliff suitability for the Peregrines. Habitat selection had fitness consequences for Eagle Owls because breeding productivity increased with cliff length. Environmental conditions, particularly climatic factors, could allow the widespread coexistence of these competing raptors at the landscape scale, whereas at the local scale co‐occurrence could take place only on larger cliffs. These were preferred sites for both species, presumably because breeding at such sites offsets the costs of settling close to the competitor species.     

森林生态系统年净初级生产力和生境复杂度对小型兽类物种多样性影响

本研究主要探讨黄龙自然保护区森林生态系统年净初级生产力水平和栖息地复杂程度对小型兽类物种多样性的影响。将调查区按海拔高度分为4 个调查点,每点的年净初级生产力水平各不相同,分别为: 24.9 MJ / (m²·a) ; 21.5 MJ / (m²·a) ; 17.5 MJ / (m²·a) 和14.1 MJ / (m²·a) 。在选择调查点时,同时考虑栖息地复杂程度,在生产力水平较高的调查点选择栖息地复杂程度较低的地点,而在生产力较低的调查点选择栖息地复杂程度较高的地点调查,以便分析森林生态系统年净初级生产力水平与栖息地复杂程度对小型兽类物种多样性的影响。采用鼠铗捕获小型兽类。结果表明,小型兽类物种多样性与森林生态系统年净初级生产力水平有密切关系,随着海拔升高,森林生态系统年净初级生产力的降低,所捕获的小型兽类生物量随之降低,其物种多样性也随之下降。小型兽类物种多样性也与栖息地复杂程度有关,森林生态系统年净初级生产力水平在一定范围内,大于17.5 MJ / (m²·a) ,栖息地复杂度的增加可以降低年净初级生产力水平对小型兽类物种多样性的影响。然而,森林生态系统年净初级生产力水平降低到一定程度时,小于14.1 MJ / (m²·a) ,生产力水平则为影响小型兽类物种多样性的主要因子。此外,小型兽类的生物量与森林生态系统年净初级生产力和栖息地复杂程度也有类似的关系。     

Bottlenecks, drift and differentiation: the population structure and demographic history of sika deer (Cervus nippon) in the Japanese archipelago

We assessed genetic differentiation and diversity in 14 populations of sika deer (Cervus nippon) from Japan and four populations of sika deer introduced to the UK, using nine microsatellite loci. We observed extreme levels of differentiation and significant differences in diversity between populations. Our results do not support morphological subspecies designations, but are consistent with previous mitochondrial DNA analyses which suggest the existence of two genetically distinct lineages of sika deer in Japan. The source of sika introduced to the UK was identified as Kyushu. The underlying structure of Japanese populations probably derives from drift in separate glacial refugia and male dispersal limited by distance. This structure has been perturbed by bottlenecks and habitat fragmentation, resulting from human activity from the mid-nineteenth century. Most current genetic differentiation and differences in diversity among populations probably result from recent drift. Coalescent model analysis suggests sika on each of the main Japanese islands have experienced different recent population histories. Hokkaido, which has large areas of continuous habitat, has maintained high levels of gene flow. In Honshu the population is highly fragmented and is likely to have been evolving by drift alone. In Kyushu there has been a balance between gene flow and drift but all the populations have experienced high levels of drift. Habitat fragment size was not significantly associated with genetic diversity in populations but there was a significant correlation between habitat fragment size and effective population size.     

Correlates of Zooplankton Beta Diversity in Tropical Lake Systems

The changes in species composition between habitat patches (beta diversity) are likely related to a number of factors, including environmental heterogeneity, connectivity, disturbance and productivity. Here, we used data from aquatic environments in five Brazilian regions over two years and two seasons (rainy and dry seasons or high and low water level periods in floodplain lakes) in each year to test hypotheses underlying zooplankton beta diversity variation. The regions present different levels of hydrological connectivity, where three regions present lakes that are permanent and connected with the main river, while the water bodies of the other two regions consist of permanent lakes and temporary ponds, with no hydrological connections between them. We tested for relationships between zooplankton beta diversity and environmental heterogeneity, spatial extent, hydrological connectivity, seasonality, disturbance and productivity. Negative relationships were detected between zooplankton beta diversity and both hydrological connectivity and disturbance (periodic dry-outs). Hydrological connectivity is likely to affect beta diversity by facilitating dispersal between habitats. In addition, the harsh environmental filter imposed by disturbance selected for only a small portion of the species from the regional pool that were able to cope with periodic dry-outs (e.g., those with a high production of resting eggs). In summary, this study suggests that faunal exchange and disturbance play important roles in structuring local zooplankton communities.     

The relationship between population density, habitat position and habitat breadth within a neotropical forest bird community

We examined the relationship between local abundance, habitat position and habitat breadth across bird species in a large Atlantic forest reserve in Brazil. This appears to be the first such study for any rainforest taxon. Habitat position for a species was its mean foraging height, along with the mean scores on three principal habitat axes for census stations at which it was recorded. Habitat breadth was the standard deviation of recorded foraging heights and the standard deviations of "positive" station scores on the habitat axes. We also examined differences in habitat position and breadth between endemic and wide-ranging taxa and amongst dietary groups. Amongst 31 species for which density estimation was possible, there were no correlations between local abundance and breadth of habitat use on any of the habitat axes. Breadth of habitat used did not vary with degree of endemism, but herbivores used a greater breadth of habitats on the axis describing canopy closure than did omnivores. Habitat position did not vary with endemic status, but herbivores preferred higher-biomass habitats than faunivores, and higher foraging heights than either faunivores or omnivores. Local abundance was linked weakly to habitat position with commoner species tending to forage in the lower strata of open-canopied areas. The 31 most commonly recorded species tended to occupy "middle-range" habitat positions, while 28 rarer species occupied habitats toward one or other end of the vegetation axes. These results suggest an association between the local abundance of a species and its habitat position, and especially its preference for common or mid-range habitats, rather than with its ability to utilise a wide range of habitats.     

Temporal scales of density‐dependent habitat selection in a large grazing herbivore

Habitat selection is a density‐dependent process, but little is known regarding how this relationship may vary across different temporal scales. Over long time scales, grazing shapes the structure, diversity and functioning of terrestrial ecosystems, and grazing‐induced changes in forage production over time are likely to affect the level of density dependence in habitat selection. In this fully‐replicated, landscape‐scale experiment, we investigated how density‐dependent habitat selection by a large grazing herbivore, sheep Ovis aries, develops over the time scale of a decade. We also address an often‐neglected challenge in habitat selection studies; namely, whether there is variation in use within a particular habitat or vegetation type and why. We found clear evidence of density dependence in habitat selection, with a wider use of habitats at high density. Despite a change in the standing biomass of high‐productivity vegetation at high herbivore density over the years, with herb biomass declining and graminoid biomass increasing, there was no clear evidence that these grazing‐induced changes in habitat over the years were strong enough to affect the level of density‐dependent habitat selection. The difference in selection for high versus low‐productivity habitats remained similar, despite annual fluctuations in the strength of selection. We found strong variation in selection within each vegetation type, even when vegetation types were mapped at a fine‐resolution scale. Our study shows that despite the interactive effects of herbivores and habitats, they are not always sufficiently strong enough to affect the level of density‐dependent habitat selection.     

Interactions between climate and habitat loss effects on biodiversity: a systematic review and meta‐analysis

Climate change and habitat loss are both key threatening processes driving the global loss in biodiversity. Yet little is known about their synergistic effects on biological populations due to the complexity underlying both processes. If the combined effects of habitat loss and climate change are greater than the effects of each threat individually, current conservation management strategies may be inefficient and at worst ineffective. Therefore, there is a pressing need to identify whether interacting effects between climate change and habitat loss exist and, if so, quantify the magnitude of their impact. In this article, we present a meta‐analysis of studies that quantify the effect of habitat loss on biological populations and examine whether the magnitude of these effects depends on current climatic conditions and historical rates of climate change. We examined 1319 papers on habitat loss and fragmentation, identified from the past 20 years, representing a range of taxa, landscapes, land‐uses, geographic locations and climatic conditions. We find that current climate and climate change are important factors determining the negative effects of habitat loss on species density and/or diversity. The most important determinant of habitat loss and fragmentation effects, averaged across species and geographic regions, was current maximum temperature, with mean precipitation change over the last 100 years of secondary importance. Habitat loss and fragmentation effects were greatest in areas with high maximum temperatures. Conversely, they were lowest in areas where average rainfall has increased over time. To our knowledge, this is the first study to conduct a global terrestrial analysis of existing data to quantify and test for interacting effects between current climate, climatic change and habitat loss on biological populations. Understanding the synergistic effects between climate change and other threatening processes has critical implications for our ability to support and incorporate climate change adaptation measures into policy development and management response.     

Habitat availability does not explain the species richness patterns of European lentic and lotic freshwater animals

Aim In Europe, the relationships between species richness and latitude differ for lentic (standing water) and lotic (running water) species. Freshwater animals are highly dependent on suitable habitat, and thus the distribution of available habitat should strongly influence large‐scale patterns of species richness. We tested whether habitat availability can account for the differences in species richness patterns between European lentic and lotic freshwater animals. Location Europe. Methods We compiled occurrence data of 1959 lentic and 2445 lotic species as well as data on the amount of lentic and lotic habitats across 25 pre‐defined biogeographical regions of European freshwaters. We used the range of elevation of each region as a proxy for habitat diversity. We investigated the relationships between species richness, habitat availability and habitat diversity with univariate and multiple regression analyses. Results Species richness increased with habitat availability for lentic species but not for lotic species. Species richness increased with elevational range for lotic species but decreased for lentic species. For both groups, neither habitat availability nor diversity could account for previously reported latitudinal patterns in species richness. For lotic species, richness declined with latitude, whereas there was no relationship between habitat availability and latitude. For lentic species, richness showed a hump‐shaped relationship with latitude, whereas available habitat increased with latitude. Main conclusions Habitat availability and diversity are poor predictors of species richness of the European freshwater fauna across large scales. Our results indicate that the distributions of European freshwater animals are probably not in equilibrium and may still be influenced by history, namely the recurrent European glaciations and possible differences in post‐glacial recolonization. The distributions of lentic species appear to be closer to equilibrium than those of lotic species. This lends further support to the hypothesis that lentic species have a higher propensity for dispersal than lotic species.     

Leaf Dry Matter Content Predicts Herbivore Productivity,but Its Functional Diversity Is Positively Related to Resilience in Grasslands

This paper addresses whether the ecosystem service of animal production from grasslands depends upon plant functional identity, plant functional diversity or if the resilience of production is a function of this diversity. Using the results of nine grazing experiments the paper shows that productivity is highly dependent on one leaf trait, leaf dry matter content, as well as rainfall. Animal (secondary) productivity is not dependent on plant functional diversity, but the variability in productivity of grasslands is related to the functional diversity of leaf dry matter content. This and a range of independent studies have shown that functional diversity is reduced at high levels of grassland productivity, so it appears that there is a trade-off between productivity and the resilience of productivity in the face of environmental variation.     

西双版纳片段化石灰岩森林附生兰科植物多样性研究

西双版纳石灰岩地区拥有丰富的兰科植物资源,但近年来随着橡胶树的大面积种植,使得该地区很多石灰岩森林呈片段化。为了解片段化石灰岩森林中附生兰科植物多样性状况以及片段化对附生兰科植物的影响,该研究选取了生境片段化的青岩寨和曼纳览,以及连续生境的绿石林和巴卡新寨等4个样地的29个样方进行多样性调查和对比研究。结果表明:4个石灰岩森林样共记录到附生兰科植物34属76种1 528株(丛)。通过对坡向、坡度、海拔、地形、郁闭度和森林类型等6个环境因子与附生兰科植物丰富度进行CCA分析,发现石灰岩地区附生兰科植物的分布主要受海拔和森林类型2个因素的影响,在海拔较高的青岩寨和巴卡新寨附生兰科植物物种丰富度高于低海拔的绿石林和曼纳览,而片段化对附生兰科植物的物种多样性和多度均无显著影响,这可能与片段化的历史较短有关。虽然目前来看生境片段化对石灰岩地区的附生兰科植物多样性无显著影响,但生境脆弱的石灰岩森林植被的保护对于兰科植物多样性保护则更具重要性。