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1.
Land cover and climate change are both major threats for biodiversity. In mountain ecosystems species have to adapt to fragmented habitats and harsh environmental conditions but so far, altitudinal effects in combination with land cover change have been rarely studied. The objective of this study was to determine the effects of altitude and historical land cover change on butterfly diversity. We studied species richness patterns of butterflies occuring in wetlands and other open habitats along an altitudinal gradient in a low mountain region (340–750 m a.s.l., Bavaria, Germany) with drastic loss of open habitats within the last 40–60 years. We recorded in 27 sites a total of 4,523 individuals of 49 butterfly species and five species of burnet moths. Species richness peaked at mid elevation and increased with patch size. Land cover change was most pronounced at high altitudes, but neither current open habitats, nor the historical loss of open habitats affected the species richness of butterflies. Neither open land specialized butterflies nor generalist and forest species were significantly affected by the loss of open habitats. However, increasing forest area in high altitudes reduces possible refuge open habitats for butterflies at their thermal distribution limits. This could lead to extinction of such butterfly species when temperatures further rise due to global warming.  相似文献   

2.
During the last decades, farmland habitats in central European countries have changed significantly, seriously affecting populations of many farmland bird species. We compiled available published data on densities of three owl species, Athene noctua, Asio otus and Strix aluco collected in the Polish farmland. All results of censuses based on the playback method conducted between 1980–2005 were included in the analysis. The proportions of grassland, fields, built-up land and forest at each studied plot were estimated and used as predictors in additive models. Proportions of main land use types, extracted with the principal component analysis, explained much of the variation found in owl densities, although some of the relationships were nonlinear. In general, owl densities were found to be affected positively by a high percentage of grasslands and built-up land, and negatively by the amount of fields and forests. Little owl densities showed a significant negative trend over the study period. It seems that high prey availability is an important factor accounting for the positive relationship between grassland proportion and owl density. The significant decrease in grassland areas and increase in forest coverage that were recently recorded in Poland may thus negatively affect populations of the three owl species studied here.  相似文献   

3.
AIM: As accurate and up-to-date distribution data for plant species are rarely available, cumulative records over long periods of time are frequently used for mapping distributions, without taking into account that species do not persist in their historical localities forever. However, persistence is highly relevant in changing modern landscapes, especially for invasive species that dynamically spread in unstable human-made habitats. We studied how an invasive species, Heracleum mantegazzianum, persists at sites once colonized and how its ability to persist affects its distribution. LOCATION: The Czech Republic. METHODS: We visited 521 localities of H. mantegazzianum occurrence reported in the literature and herbaria to determine whether the species still occurs at these sites. By using G-tests and classification trees, we explored the roles of various factors affecting its persistence at a site. RESULTS: Of the total number of 521 historical sites at which the species has occurred since the end of the 19th century, it persists at only 124 (23.8%). The persistence rate differs with respect to habitat type and is highest in meadows and forest margins. Analysis using classification trees indicated that the factors that best explain persistence are: type of habitat (with meadow and forest margins over-represented); urbanity (with a higher persistence outside urban areas); proximity to the place of the species' introduction into the country; metapopulation connectivity; and distance to the nearest neighbouring population. MAIN CONCLUSIONS: The use of cumulative historical records as a measure of species distribution, which is common in invasion literature, can seriously overestimate the actual distribution of alien plant species with low persistence. In the case of alien species such as H. mantegazzanium, which is non-clonal and reproduces only by seed, estimates of distribution and spread based on historical data are informative about potentially suitable habitat but may be unreliable as indicators of current occurrence and invasion dynamics.  相似文献   

4.
Plant species richness in central and northern European seminatural grasslands is often more closely linked to past than present habitat configuration, which is indicative of an extinction debt. In this study, we investigate whether signs of historical grassland management can be found in clear‐cuts after at least 80 years as coniferous production forest by comparing floras between clear‐cuts with a history as meadow and as forest in the 1870s in Sweden. Study sites were selected using old land‐use maps and data on present‐day clear‐cuts. Species traits reflecting high capacities for dispersal and persistence were used to explain any possible links between the plants and the historical land use. Clear‐cuts that were formerly meadow had, on average, 36% higher species richness and 35% higher richness of grassland indicator species, as well as a larger overall seed mass and lower anemochory, compared to clear‐cuts with history as forest. We suggest that the plants in former meadows never disappeared after afforestation but survived as remnant populations. Many contemporary forests in Sweden were managed as grasslands in the 1800s. As conservation of remaining grassland fragments will not be enough to reduce the existing extinction debts of the flora, these young forests offer opportunities for grassland restoration at large scales. Our study supports the concept of remnant populations and highlights the importance of considering historical land use for understanding the distribution of grassland plant species in fragmented landscapes, as well as for policy‐making and conservation.  相似文献   

5.
Landscape context and contrast are major features of transformed landscapes. These concepts are largely described in terms of vegetation and land use, and are rarely used on how other biodiversity responds to these anthropogenic boundaries. South African grassland matrix is naturally dotted with indigenous forest patches which have recently been transformed with plantations of non-native species. We investigate how various arthropod groups (detritivores, predators, ants) respond to juxtaposition of pines, natural forests and grasslands. We assess landscape context effects between natural forests and pines by determining how species that commonly occur in the interiors of these habitats use the adjacent habitat, and how landscape contrast between natural forests and grassland affects these groups proportionately. We sampled arthropods using pitfall traps and active searches in transects running from natural forest interiors across the edge into the matrix interior (grassland or pines). Natural forests had higher predator and detritivore diversity, while grassland had greater ant diversity. Results highlighted the complementarity of natural forests and grassland for arthropod diversity. Higher beta-diversity was recorded across landscape contrast than landscape context. Pine and natural forest associated species overlapped into adjacent habitats indicating that pines are used by certain natural forest species. However, pines are not true natural forest extensions, with only some species being supported. Pines may be connecting naturally isolated arthropod populations, which could have important evolutionary consequences. Only through appreciation of a range of arthropod groups and their response to context and contrast across the whole landscape can we undertake meaningful biodiversity conservation.  相似文献   

6.
To discern mechanisms maintaining the diversity of grassland and forest butterflies in coppice woods managed for the production of Japanese forest mushroom logs, we investigated the butterfly fauna in cut-over land tracts shortly after felling and 5 year later, and in forest stands 10, 15, and 25 year after felling (here, we use the term “forests” when referring to the chronosequence of these treed stands). Butterfly species richness and diversity (H′) and the densities of individuals were highest in cut-over lands 5 year after clear-cutting, followed by 25-year-old forest stands. In forests, the richness and densities of forest butterfly species were higher than were those of grassland species. Among forest stands of different ages, forest butterfly species’ richness and the densities of individuals were highest in 25-year-old woods nearing felling time. Some forest butterfly species were observed only in forests. The species richness and densities of grassland butterflies were much higher in cut-over lands 0 and 5 year post felling than in forests; grassland species were rarely found in stands ≥10 year old. Thus, cut-over lands seem to function as temporary habitats for grassland species. Furthermore, the number of forest butterfly species was the same in cut-over lands 5 year after felling and in 25-year-old forest stands; the densities of forest butterfly species was higher in these cut-over lands than in the forest stands. Forest butterfly species living on cut-over land 5 year post felling sipped flower nectar, laid eggs on host plants, and practiced territorial behaviour involved in mate finding. Hence, these cut-over lands functioned as important habitats for various developmental stages of forest butterflies. In conclusion, traditional coppicing in woods for production of Japanese forest mushroom logs is very important for the maintenance of diversity in grassland and forest butterfly species.  相似文献   

7.
A long-term assumption in ecology is that species distributions correspond with their niche requirements, but evidence that species can persist in unsuitable habitat for centuries undermines the link between species and habitat. Moreover, species may be more dependent on mutualist partners than specific habitats. Most evidence connecting indigenous cultures with plant dispersal is anecdotal, but historical records suggest that Native Americans transported and cultivated many species, including Gleditsia triacanthos ("Honey locust"). Gleditsia triacanthos was an important medicinal/culinary (e.g., sugar), cultural (e.g., game sticks) and spiritual tree for the Cherokee (southeastern U.S. Native Americans). This study tests the hypothesis that a Cherokee cultivation legacy drives current regional G. triacanthos distribution patterns. Gleditsia triacanthos occurs in rocky uplands and xeric fields, but inexplicably also occurs in mesic riverine corridors and floodplains where Cherokee once settled and farmed. I combined field experiments and surveys in the Southern Appalachian Mountain region (U.S.) to investigate G. triacanthos recruitment requirements and distribution patterns to determine whether there is a quantifiable G. triacanthos association with former Cherokee settlements. Moreover, I also investigated alternate dispersal mechanisms, such as stream transport and domestic cattle. The results indicate that a centuries-old legacy of Native American cultivation remains intact as G. triacanthos'' current southern Appalachian distribution appears better explained Cherokee settlement patterns than habitat. The data indicate that the tree is severely dispersal limited in the region, only moving appreciable distances from former Cherokee settlements where cattle grazing is prevalent. Human land use legacy may play a long-term role in shaping species distributions, and pre-European settlement activity appears underrated as a factor influencing modern tree species distributions.  相似文献   

8.
European calcareous grasslands have decreased dramatically in area and number during the last two centuries. As a result, many populations of calcareous grassland species are confined to small and isolated fragments, where their long-term survival is to some extent uncertain. Recently, several restoration projects have been initiated to enlarge the current grassland area in order to maintain the exceptionally high species richness. However, from a genetic point of view, the success of these restoration measures is not necessarily guaranteed, as strong historical decreases in population size and limited gene flow may have led to low genetic diversity through genetic bottlenecks and drift. In this study, we investigated genetic diversity and structure of 16 populations of the calcareous grassland specialist Cirsium acaule in a severely fragmented landscape in south-western Belgium. The overall distribution of this species in the study area was significantly and positively related to patch area, suggesting that small patches do not allow survival of this species. Both allelic richness and genetic diversity were significantly and positively related to population size. Estimation of observed and expected gene diversity provided evidence for population bottlenecks in the history of not less than 31% of all sampled populations. Reconstruction of the historical land use showed that patch area decline in populations that went through a recent bottleneck was significantly larger than that in populations that showed no evidence of a bottleneck. Assignment analyses showed low migration rates, suggesting that replenishment of lost alleles through gene flow is highly unlikely. Overall, our results indicate that in the absence of gene flow strong decreases in calcareous grassland area may have long-lasting effects on genetic diversity of plant populations and may hamper the success of restoration projects that simply aim at restoring initial habitat conditions or enlarging population fragments, as indicated by the fact that none of the recently restored areas has been occupied by C. acaule.  相似文献   

9.
马琦  李爱民  邓合黎 《生态学报》2012,32(5):1458-1470
在三峡库区蝶类物种多样性调查基础上,从等级多样性角度进行分析,结果表明,蝴蝶属级,科级和等级多样性指数在灌丛生境较高,森林、农田和草地生境多样性较低;非参数检验和方差分析结果表明4种生境在属级和等级多样性上差异显著,灌丛生境和其他生境差异显著。海拔500-1500m高度,蝴蝶的生物多样性相对较高,是库区蝴蝶最重要的生存地带。属级和科级多样性指数的变异系数在森林植被型样本间最大,前者有4个小生境在100%以上,后者有6个小生境超过100%;农田科的变异系数有1个小生境超过100%;草地的属和科变异系数均是1个小生境超过100%;灌丛则全部低于100%。这些数值,反映了三峡库区的形成对蝴蝶的生存及分布的产生了很大的影响,进一步证明库区蝶类生存环境的多样性和破碎化;其中,森林对蝴蝶生存的影响是最复杂的;通过蝴蝶做环境质量评估时,灌丛可作为首选考察对象。  相似文献   

10.
Seed bank species-composition and seed-density were determined in a successional calcareous (alvar) grassland in western Estonia. Three similar study areas were chosen to compare two different successional stages: open alvar grassland and overgrown areas with young pine forest 30 to 40 years old. In both successional stages, the centre and the edge of a relatively uniform stand were examined. Fifteen soil samples (7 cm in diameter, 5 cm deep) were taken from each of twelve sampling sites. The seedling emergence method was used to estimate seeds in the soil samples. A total of 69 species were detected in the seed bank, of which 18 did not occur in the vegetation. Eighty-nine taxa were recorded in the vegetation and of these 38 were not detected in the seed bank. Fifty-one species occurred both in the seed bank and in the vegetation. The three most abundant taxa in the seed bank wereCarex tomentosa, Linum catharticum andPlantago media, which together made up 49% of the seedlings recorded. Differences in the species compositions of seed bank samples from grassland and forest sites were negligible, although the species richness per area of the above-ground vegetation was significantly higher in the open grassland. The only species tending to be lost from forest site vegetation but still occurring in the forest soil seed bank wereArenaria serpylifolia, Cerastium fontanum andLinum catharticum. About half of all the emerged species from all samples belonged to the transient or short-term persistent seed bank. In the grassland sites there were more species which belonged to the transient seed bank than in the forest sites, where the seed bank contained more short-term persistent type seeds. The seed density was significantly higher in forest sites and lower in grassland sites, which may be explained by the better germination conditions in well-illuminated communities. On the basis of the current study it might be assumed that the soil seed banks of overgrown alvar grasslands which include young pine forests can play a certain role in grassland restoration management.  相似文献   

11.
We studied the distribution of millipedes in a forest interior-forest edge-grassland habitat complex in the Hajdúság Landscape Protection Area (NE Hungary). The habitat types were as follows: (1) lowland oak forest, (2) forest edge with increased ground vegetation and shrub cover, and (3) mesophilous grassland. We collected millipedes by litter and soil sifting. There were overall 30 sifted litter and soil samples: 3 habitat types × 2 replicates × 5 soil and litter samples per habitats. We collected 9 millipede species; the most abundant species was Glomeris tetrasticha, which was the most abundant species in the forest edge as well. The most abundant species in the forest interior was Kryphioiulus occultus, while the most abundant species in the grassland was Megaphyllum unilineatum. Our result showed that the number of millipede species was significantly lower in the grassland than in the forest or in the edge, however there were no significant difference in the number of species between the forest interior and the forest edge. We found significantly the highest number of millipede individuals in the forest edge. There were differences in the composition of the millipede assemblages of the three habitats. The results of the DCCA showed that forest edge and forest interior habitats were clearly separated from the grassland habitats. The forest edge habitat was characterized by high air temperature, high soil moisture, high soil pH, high soil enzyme activity, high shrub cover and low canopy cover. The IndVal and the DCCA methods revealed the following character species of the forest edge habitats: Glomeris tetrasticha and Leptoiulus cibdellus. Changes in millipede abundance and composition were highly correlated with the vegetation structure.  相似文献   

12.
Endophytic fungi are known to be commonly associated with herbaceous plants, however, there are few studies focusing on their occurrence and distribution in plant roots from ecosystems with different land uses. To explore the phylogenetic diversity and community structure of Sebacinales endophytes from agricultural and grassland habitats under different land uses, we analysed the roots of herbaceous plants using strain isolation, polymerase chain reaction (PCR), transmission electron microscopy (TEM) and co-cultivation experiments. A new sebacinoid strain named Serendipita herbamans belonging to Sebacinales group B was isolated from the roots of Bistorta vivipara, which is characterized by colourless monilioid cells (chlamydospores) that become yellow with age. This species was very common and widely distributed in association with a broad spectrum of herbaceous plant families in diverse habitats, independent of land use type. Ultrastructurally, the presence of S. herbamans was detected in the cortical cells of Plantago media, Potentilla anserina and Triticum aestivum. In addition, 13 few frequent molecular operational taxonomic units (MOTUs) or species were found across agricultural and grassland habitats, which did not exhibit a distinctive phylogenetic structure. Laboratory-based assays indicate that S. herbamans has the ability to colonize fine roots and stimulate plant growth. Although endophytic Sebacinales are widely distributed across agricultural and grassland habitats, TEM and nested PCR analyses reinforce the observation that these microorganisms are present in low quantity in plant roots, with no evidence of host specificity.  相似文献   

13.
Upland calcareous grassland landscapes are typically comprised of a matrix of calcareous grassland, acid grassland and limestone heath plant communities. This matrix of habitats is produced by a combination of underlying geology, climate and management. These landscapes are typically managed through grazing, with management targeted to maintain particular plant communities in the calcareous grassland habitat, whilst patches of acid grassland and limestone heath are not targeted by conservation management. The biodiversity value of acid grassland and limestone heath patches within the calcareous grassland matrix are unknown. This study provides the first assessment of their biodiversity value by examining aspects of epigeal spider diversity supported by these non-target habitat patches in comparison to calcareous grassland. Spiders were sampled in each habitat from April to August 2014 using pitfall traps across three upland regions in Great Britain. Spider species assemblages were distinct between limestone heath and both grassland types. Distinction in species assemblages are likely due to differences in vegetation structure and microclimate, e.g., humidity, degree of shade. Each habitat type supported several rare species (e.g., Jacksonella falconeri, Agyneta subtilis) revealing the contribution to spider fauna. The distinct spider species assemblage and presence of rare species in limestone heath patches demonstrate their importance in the upland calcareous grassland matrix. This study highlights the value of monitoring biodiversity in non-target habitats within a habitat matrix alongside those that are actively targeted by management.  相似文献   

14.
Many grassland specialist plant populations in Europe have become restricted to remnant habitats. The performance of these populations depends on both species‐specific traits and local and landscape level aspects of habitat quality. Understanding which specific local or landscape level conditions determine the performance of grassland species populations in remnant habitats would help design the restoration of the habitats and to detect the conditions that favour the long‐term persistence of grassland species in them. Such information is especially needed in urbanised landscapes, where remnant habitats engulfed by urban land use types may experience increased erosion, higher temperatures and invasion by alien species. This study investigates the population performance determinants of Carex caryophyllea (VU), a grassland specialist, in 43 remnant grasslands in an urban‐rural gradient in Finland. The population performance was assessed with metrics of persistence, establishment and reproduction, and related to environmental conditions with generalized additive models and redundancy analysis. The most important positive determinants for the performance of C. caryophyllea populations were disturbance through management or ground erosion, a warm microclimate, large habitat area and high historical connectivity to suitable grassland habitats. Present connectivity to other C. caryophyllea populations had a weak and near‐significant positive relationship with population performance. Urbanisation of the surrounding landscape correlated with population performance as well, possibly due to the high historical cover of grasslands in presently urbanised landscapes. The results imply that the most effective restoration method of remnant C. caryophyllea populations would be reinstating disturbance regimes in overgrown habitats with warm microclimates close to suitable habitats and other existing populations, whether urban or rural. This would counteract the species future decline due to possible extinction debts and help the species persist in the study area in the long term.  相似文献   

15.
We present logistic regression models predicting the distribution and abundance of a threatened cryptic lizard, Delma impar (Pygopodidae), in the Australian Capital Territory (ACT). The models incorporate current habitat and historical land use and habitat change (woodland clearance, ploughing, grazing, fertilizer application). Information on historical land use was acquired from land survey maps, aerial photographs and from floristic indices of land management. Floristic indices were developed from a survey of local agronomists who scored individual plant species, responses to grazing, ploughing and fertilizer application. Floristic indicies proved to be more informative than floristic ordination analyses. It emerged that historical factors were of key importance for predicting the distribution and abundance of D. impar. Since European settlement, D. impar has apparently spread from primary (naturally treeless grasslands) into secondary grasslands (grassland formerly with an overstorey of trees) and has been locally excluded by some farming activities such as ploughing. We conclude that a combination of current habitat and past changes in habitat may be necessary to understand the current distributions of plant and animal species that have limited dispersal ability and that are susceptible to local temporary habitat destruction. Active conservation strategies involving, for example, assisted dispersal, may be important for these species.  相似文献   

16.
We tested the prediction that forest habitat types with relatively high productivity are not only relatively low in species richness but are also regionally uncommon. This relationship was supported by an analysis of data from 146 forest communities in southern Ontario, Canada. Potential forest habitat productivity was determined based on a classification scheme developed for the Canadian Land Inventory (CLI) project. Vascular plant species richness approximated a unimodal distribution across forest productivity classes with the lowest mean species richness recorded for the two most productive classes. The contemporary regional commonness of forest habitat productivity classes were also displayed as a unimodal frequency distribution. Hence, mean species richness per CLI class was positively correlated with the regional area of land encompassing each of these productivity classes and this relationship was increasingly significant at increasingly larger spatial scales of regional CLI class land areas. These results are consistent with the species pool hypothesis, which postulates that species richness is relatively low in highly productive habitats because such habitats have been relatively uncommon in both space and time and hence, have had relatively little historical opportunity for the origination of adapted species.  相似文献   

17.

Questions

What are the most important drivers of plant species richness (gamma‐diversity) and species turnover (beta‐diversity) in the field layer of a forest edge? Does the tree and shrub species richness structure and complexity affect the richness of forest and grassland specialist species?

Location

Southeast Sweden.

Methods

We sampled 50 forest edges with different levels of structural complexity in agricultural landscapes. In each border we recorded trees, shrubs and herb layer species in a 50‐m transect parallel with the forest. We investigated species composition and species turnover in relation to the proportions of gaps in the border and the diversity of trees and shrubs.

Results

Total plant species richness in the field layer was mainly explained by the proportion of gaps to areas with full canopy cover and tree diversity. Increasing number of gaps promoted higher diversity of grassland specialist species within the field layer, resulting in open forest borders with the highest overall species richness. Gaps did however have a negative impact on forest species richness. Conversely, increasing forest species richness was positively related to tree diversity, but the number of grassland specialist species was negatively affected by tree diversity.

Conclusions

Managing forest borders, and therefore increasing the area of semi‐open habitats in fragmented agricultural landscapes, provides future opportunities to create a network of suitable habitats for both grassland and deciduous forest specialist species. Such measures therefore have the potential to increase functional connectivity and support dispersal of species in homogeneous forest/agricultural landscapes.  相似文献   

18.
Greater sage‐grouse Centrocercus urophasianus (Bonaparte) currently occupy approximately half of their historical distribution across western North America. Sage‐grouse are a candidate for endangered species listing due to habitat and population fragmentation coupled with inadequate regulation to control development in critical areas. Conservation planning would benefit from accurate maps delineating required habitats and movement corridors. However, developing a species distribution model that incorporates the diversity of habitats used by sage‐grouse across their widespread distribution has statistical and logistical challenges. We first identified the ecological minimums limiting sage‐grouse, mapped similarity to the multivariate set of minimums, and delineated connectivity across a 920,000 km2 region. We partitioned a Mahalanobis D2 model of habitat use into k separate additive components each representing independent combinations of species–habitat relationships to identify the ecological minimums required by sage‐grouse. We constructed the model from abiotic, land cover, and anthropogenic variables measured at leks (breeding) and surrounding areas within 5 km. We evaluated model partitions using a random subset of leks and historic locations and selected D2 (k = 10) for mapping a habitat similarity index (HSI). Finally, we delineated connectivity by converting the mapped HSI to a resistance surface. Sage‐grouse required sagebrush‐dominated landscapes containing minimal levels of human land use. Sage‐grouse used relatively arid regions characterized by shallow slopes, even terrain, and low amounts of forest, grassland, and agriculture in the surrounding landscape. Most populations were interconnected although several outlying populations were isolated because of distance or lack of habitat corridors for exchange. Land management agencies currently are revising land‐use plans and designating critical habitat to conserve sage‐grouse and avoid endangered species listing. Our results identifying attributes important for delineating habitats or modeling connectivity will facilitate conservation and management of landscapes important for supporting current and future sage‐grouse populations.  相似文献   

19.
The conservation and sustainable management of forests has become an important issue, especially in ecosystems where keystone species form unique and marginal forest habitats with narrow distribution. With increasing pressures and threats to nature, the establishment of Protected Areas has been recognized as a major tool for maintaining well-functioning forest ecosystems and their associated ecosystem services (ES). This study aims at assessing the changes in the status of a narrowly distributed Mediterranean forest through the perspective of land cover dynamics and the ES framework. Using the priority habitat of Cedrus brevifolia forest as a case study, the distribution of land use and land cover (LULC) was mapped and simulated, together with the supply of multiple ES before and after the implementation of conservation measures. The results prior applying the management actions revealed a general pattern of forest densification that did not act fully in favor of C. brevifolia due to competitions among forest species. From an ES viewpoint, forest densification led to landscape homogenization affecting important ES such as the increase in the supply of regulating services, and the decrease in the ability to support nursery populations and habitats. By contrast, the future simulation of LULC integrated with afforestation and thinning measures showed an expected increase in both high-density vegetation and cedar trees, benefiting multiple ES. The current findings highlight the importance of sustainable forest management in enhancing the co-occurrence of several ES and supporting the overall multi-functionality of ecosystems. The holistic approach presented in this study can offer new insights into the relation between ES and natural ecosystem and/or habitats’ management while avoiding potential negative impacts on human well-being and ecosystem resilience.  相似文献   

20.
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