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1.
Different taxonomic groups perceive and respond to the environment at different scales. We examined the effects of spatial scale on diversity patterns of butterflies and birds in the central Great Basin of the western USA. We partitioned the landscape into three hierarchical spatial levels: mountain ranges, canyons, and sites within can yons. We evaluated the relative contribution of each level to species richness and quantified changes in species composition at each level. Using additive partitioning, we calculated the contribution of spatial level to overall species diversity. Both canyon and mountain range had significant effects on landscape-level species richness of butterflies and birds. Species composition of butterflies was more similar in space than species composition of birds, but assemblages of both groups that were closer together in space were less similar than assemblages that were further apart. These results likely reflect differences in resource specificity and the distribution of resources for each group. Additive partitioning showed that alpha diversity within canyon segments was the dominant component of overall species richness of butterflies but not of birds. As the size of a sampling unit increased, its contribution to overall species richness of birds increased monotonically, but the relationship between spatial scale and species richness of butterflies was not linear. Our work emphasizes that the most appropriate scales for studying and conserving different taxonomic groups are not the same. The ability of butterflies and birds to serve as surrogate measures of each others diversity appears to be scale-dependent.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
2.
3.
Gap Analysis takes a proactive landscape-level approach to conserving native species by identifying nodes of high biological diversity. It uses vertebrate species richness as an index of overall biological diversity. However, it remains unknown whether or not the spatial distribution of vertebrate diversity corresponds with the diversity of other taxa. We tested whether landscape-level diversity patterns corresponded between a vertebrate and an invertebrate taxon, mammals and ants, across the southern half of the Florida peninsula, USA. Composite digital maps with a 30-m spatial resolution were produced for each taxon. Spatial correspondence between the taxa was determined by normalizing and then subtracting the composite maps. There were large areas of spatial correspondence – indicating that richness between mammals and ants was similar over much of southern Florida. However, spatial correspondence occurred where the richness of both taxa was low or moderate, and areas with the highest species richness (highest 20%) for each taxon, the explicit focus of Gap Analyses, corresponded over only 8752 ha. Gap Analysis provides a much needed assessment of landscape-level diversity patterns and proactive reserve design, but it must be explicit that the results are applicable for vertebrate diversity, which does not necessarily correspond with diversity patterns of other taxa. The two taxa investigated differ by orders of magnitude in the scale that they perceive their environment, and it is likely that diversity hotspots vary as the scale of investigation – and the taxa mapped – vary. 相似文献
4.
Land-bridge islands formed by dam construction are considered to be “experimental” systems for studying the effects of habitat
loss and fragmentation, offering many distinct advantages over terrestrial fragments. The Thousand Island Lake in Southeast
China is one such land-bridge system with more than 1000 islands. Based on a field survey of vascular plant richness on 154
land-bridge islands during 2007–2008, we examined the effects of island and landscape attributes on plant species richness
and patterns of species nestedness. We also examined the different responses of plant functional groups (classified according
to growth form and shade tolerance) to fragmentation. We found that island area explained the greatest amount of variation
in plant species richness. Island area and shape index positively affected species diversity and the degree of nestedness
exhibited by plant communities while the perimeter to area ratio of the islands had a negative effect. Shade-tolerant plants
were the most sensitive species group to habitat fragmentation. Isolation negatively affected the degree of nestedness in
herb and shade-intolerant plants including species with various dispersal abilities in the fragmented landscape. Based on
these results, we concluded that the effects of habitat loss and fragmentation on overall species richness depended mostly
on the degree of habitat loss, but patterns of nestedness were generated from different ecological mechanisms due to species-specific
responses to different characteristics of habitat patches. 相似文献
5.
Urban parks comprise diverse microhabitats, such as vegetation units of lawn and arbour forests, with differing biodiversity potentials. However, the influences of microhabitats on butterfly diversity and the mechanisms involved remain unclear. This study used butterfly survey data from 112 plots in 27 urban parks in the central metropolitan area of Beijing, China, from June to September 2020. Based on the growth form of larval host plants, recorded butterfly species were classified into three functional groups: woody plant-feeding taxa (WF), herb-feeding taxa (HF), and feeding on multiple plant growth forms taxa (MF). We analysed the effects of 11 variables among three facets, namely, vegetation composition, vegetation structure, and human activity, on the butterfly diversity (species richness and abundance) of the whole community, three functional groups using generalised linear mixed models. Twenty-five butterfly species observed mainly feed on herbs rather than on woody plants. Our results demonstrated that vegetation community characteristics explain up to 24% and 43% variation in butterfly species richness and abundance, respectively. Of this, vegetation structure facets crucially affected butterfly species richness, and vegetation composition facets had the most significant influence on the abundance of the whole butterfly community. However, the impact of human activity factors was minimal. Light availability and herb height belonging to vegetation structure factors and nectar plant species richness and nectar abundance which belonged to vegetation composition factors showed the most important and positive effects on butterfly diversity. The positive impact of the above significant factors was found especially on herb-feeding butterfly diversity. In contrast, the diversity of butterflies feeding on woody plants was most positively influenced by herb height. We thus suggest that it is necessary to guarantee the presence of a well-developed herb layer, which provides abundant nectar sources and maintain specific open spaces to ensure light availability. In conclusion, our findings imply that the critical role of the spatial structure of vegetation community is conspicuous in the formation of suitable microhabitats for butterflies, and managers could combine vegetation management practices with the needs of specific functional groups. 相似文献
6.
Habitat fragmentation strongly affects insect species diversity and community composition, but few studies have examined landscape
effects on long term development of insect communities. As mobile consumers, insects should be sensitive to both local plant
community and landscape context. We tested this prediction using sweep-net transects to sample insect communities for 8 years
at an experimentally fragmented old-field site in northeastern Kansas, USA. The site included habitat patches undergoing secondary
succession, surrounded by a low turf matrix. During the first 5 years, plant richness and cover were measured in patches.
Insect species richness, total density, and trophic diversity increased over time on all transects. Cover of woody plants
and perennial forbs increased each year, adding structural complexity to successional patches and potentially contributing
to increased insect diversity. Within years, insect richness was significantly greater on transects through large successional
patches (5000 m2) than on transects through fragmented arrays of 6 medium-sized (total area 1728 m2) or 15 small (480 m2) patches. However, plant cover did not differ among patch types and was uncorrelated with insect richness within years. Insect
richness was strongly correlated with insect density, but trophic and α diversities did not differ among patch types, indicating
that patch insect communities were subsets of a common species pool. We argue that differences in insect richness resulted
from landscape effects on the size of these subsets, not patch succession rates. Greater insect richness on large patches
can be explained as a community-level consequence of population responses to resource concentration. 相似文献
7.
Different organisms respond to landscape configuration and spatial structure in different terms and across different spatial
scales. Here, regression models with variation partitioning were applied to determine relative influence of the three groups
of variables (climate, land use and environmental heterogeneity) and spatial structure variables on plant, bird, orthopteran
and butterfly species richness in a region of the Southern Alps, ranging in elevation from the sea level to 2,780 m. Grassland
and forest cover were positively correlated with species richness in both taxonomic groups, whilst species richness decreased
with increasing urban elements and arable land. The variation was mainly explained by the shared component between the three
groups in plants and between landscape and environmental heterogeneity in birds. The variation was related to independent
land use effect in insects. The distribution in species richness was spatially structured for plants, birds and orthopterans,
whilst in butterflies, no spatial structure was detected. Plant richness was associated with linear trend variation and broad-scale
spatial structure in the northern part of the region, whilst bird richness with broad-scale variation which occurs on the
external Alpine ridge. Orthopteran diversity was strongly related to fine-scale spatial structure, generated by dynamic processes
or by unmeasured spatially structured abiotic factors. Although the study was carried out in relatively small area, the four
taxonomic groups seem to respond to biodiversity drivers in a surprisingly different way. This has considerable implications
for conservation planning as it restricts the usefulness of simple indicators in prioritizing areas for conservation purposes. 相似文献
8.
Context
The world is becoming increasingly urbanized, with more than half of the global population now living in cities. Understanding the factors impacting natural communities in fragmented landscapes is therefore crucial for predicting how the remaining ecosystems will respond to global change. Ground-active arthropods, which are important in nutrient cycling, are likely sensitive to habitat changes resulting from urbanization.Objectives
We addressed two questions: (1) What is the relative importance of local and landscape factors in shaping ground-active arthropod communities in urban woodlands? (2) How does body size (as a surrogate for dispersal ability) affect sensitivity to landscape-level factors?Methods
In the summers of 2010 and 2011, we sampled ground-active arthropod communities in 19 woodlands in the Chicago metropolitan region using pitfall traps. We also assessed local plant and soil characteristics, as well as landscape-level variables using GIS.Results
Redundancy analyses and variation partitioning revealed that local factors, particularly invasive woody-plant cover and soil nitrate, had the most influence on arthropod communities, explaining 12% of the total variation. Of the landscape-level variables, landscape richness, which is one measure of landscape fragmentation, explained the most variation; however, the shared variance between landscape and local variables was responsible for half (16%) of the total explained variation (32%). Landscape factors alone explained only 4% of variation. No relationship between arthropod body size and landscape variables was observed, but several groups (e.g. ants and ground beetles) were correlated with landscape-level factors.Conclusions
Our research shows that both local and landscape variables are important in influencing ground-active arthropods, but the majority of explained variance is attributed to the covariation between landscape richness, invasive woody-plant cover, and soil nitrate. We therefore conclude that landscape fragmentation is likely affecting the ground-active arthropods through its positive influence on invasive woody plants and soil nitrogen.9.
G.H. Stewart C.D. Meurk M.E. Ignatieva H.L. Buckley A. Magueur B.S. Case M. Hudson M. Parker 《Urban Forestry & Urban Greening》2009,8(3):149-162
Urban forests are increasingly valued for multiple benefits such as amenity, cultural values, native biodiversity, ecosystem services, and carbon sequestration. Urban biodiversity in particular, is the new focus although global homogenisation is undermining regional differentiation. In the northern hemisphere (e.g., Canada and USA) and in the southern hemisphere, particularly in countries like South Africa, Australia, South America and New Zealand, local biodiversity is further impacted by historical colonisation from Europe. After several centuries, urban forests are now composed of synthetic and spontaneous mixtures of native species, and exotic species from around the temperate world (e.g., Europe, North and South America, South Africa, Asia). As far as we are aware no-one has carried out in-depth study of these synthetic forests in any Southern Hemisphere city. Here we describe the composition, structure, and biodiversity conservation imperatives of urban temperate forests at 90 random locations in Christchurch city, New Zealand.We document considerable plant diversity; the total number of species encountered in the 253 sampled urban forest patches was 486. Despite this incredibly variable data set, our ability to explain variation in species richness was surprisingly good and clearly indicates that total species richness was higher in larger patches with greater litter and vegetation cover, and taller canopy height. Species richness was also higher in patches surrounded by higher population densities and closer to very large native forest patches. Native species richness was higher in patches with higher soil pH, lower canopy height, and greater litter cover and in patches closer to very large native forest patches indicating dispersal out of native areas and into gardens. Eight distinct forest communities were identified by Two-Way INdicator SPecies ANalysis (TWINSPAN) using the occurrence of 241 species that occurred in more than two out of all 253 forest patches.Christchurch urban forest canopies were dominated by exotic tree species in parklands and in street tree plantings (linear parkland). Native tree and shrub species were not as common in public spaces but their overall density high in residential gardens. There was some explanatory power in our data, since less deprivation resulted in greater diversity and density, and more native species, which in turn is associated with private ownership. We hypothesise that a number of other factors, which were not well reflected in our measured environmental variables, are responsible for much of the remaining variation in the plant community structure, e.g., advertising, peoples choice. For a more sustainable asset base of native trees in New Zealand cities we need more, longer-lived native species, in large public spaces, including a greater proportion of species that bear fruit and nectar suitable for native wildlife. We may then achieve cities with ecological integrity that present multiple historical dimensions, and sequester carbon in legible landscapes. 相似文献
10.
Marie-Hélène Lizée Stéphanie Manel Jean-Fran?ois Mauffrey Thierry Tatoni Magali Deschamps-Cottin 《Landscape Ecology》2012,27(2):159-169
The aim of this paper is to examine the role of urban public parks in maintaining connectivity and butterfly assemblages.
Using a regression framework, we first test the relative importance of park size and isolation in predicting abundance and
species richness of butterfly assemblages across a set of 24 public parks within a large metropolitan area, Marseille (South-East
France). Then, we focus on landscape features that affect diversity patterns of the recorded butterfly communities. In this
second part, the urban landscape surrounding each park is described (within a 1 × 1 km window) according to two major components:
vegetated areas (habitat patches) and impervious or built areas (matrix patches). Specifically, we aim to test whether the
incorporation of this built component (matrix) in the landscape analysis provides new insights into the understanding of ecological
connectivity in the urban environment. We found a significant effect of both matrix configuration (shape complexity of the
built patches) and distance from regional species pool (park isolation) on diversity of butterflies that overrides park size
in their contribution to variation in species richness. This result suggests that many previous studies of interactions between
biodiversity and urban landscape have overlooked the influence of the built elements. 相似文献
11.
Despite good theoretical knowledge about determinants of plant species richness in mosaic landscapes, validations based on
complete surveys are scarce. We conducted a case study in a highly fragmented, traditional agricultural landscape. In 199
patches of 20 representative multi-patch-plots (MPPs, 1 ha) we recorded a total of 371 plant species. In addition to an additive
partitioning of species diversity at the (a) patch- and (b) MPP-scale, we adopted the recently proposed ‘specificity’ measure
to quantify the contribution of a spatial subunit to landscape species richness (subunit-to-landscape-contribution, SLC).
SLC-values were calculated at both scales with respect to various spatial extents. General regression models were used to
quantify the relative importance of hypothesis-driven determinants for species richness and SLC-values.
At the patch scale, habitat type was the main determinant of species richness, followed by area and elongated shape. For SLC-values,
area was more important than habitat type, and its relevance increased with the extent of the considered landscape. Influences
of elongated shape and vegetation context were minor. Differences between habitat types were pronounced for species richness
and also partly scale-dependent for SLC-values.
Relevant predictors at the MPP-scale were nonlinear habitat richness, the gradient from anthropogenic to seminatural vegetation,
and the proportions of natural vegetation and rare habitats. Linear elements and habitat configuration did not contribute
to species richness and SLC. Results at the MPP-scale were in complete accordance with the predictions of the mosaic concept.
Hence, our study represents its first empirical validation for plant species diversity in mosaic landscapes. 相似文献
12.
The aim of this study was to explore different components of avian diversity in two types of urban green areas, parks and cemeteries, in four European countries in relation to environmental characteristics. We studied bird species richness, functional diversity and evolutionary distinctiveness in 79 parks and 90 cemeteries located in four European countries: the Czech Republic, France, Italy and Poland.First, we found no significant differences between cemeteries and parks in bird diversity. However, in both parks and cemeteries, only: two community metrics were affected by different environmental characteristics, including local vegetation structure and presence of human-related structures. Species richness was positively correlated with tree coverage and site size, functional diversity was unrelated to any of the measured variables, while the mean evolutionary distinctiveness score was positively correlated with tree coverage and negatively associated with the coverage of flowerbeds and number of street lamps.Our findings can be useful for urban planning: by increasing tree coverage and site size it is possible to increase both taxonomic richness and evolutionary uniqueness of bird communities. In both parks and cemeteries, the potential association between light pollution and bird species richness was negligible. We also identified some thresholds where bird diversity was higher. Bird species richness was maximized in parks/cemeteries larger than 1.4 ha, with grass coverage lower than 65%. The evolutionary uniqueness of bird communities was higher in areas with tree coverage higher than 45%. In conclusion, the findings of this study provide evidence that cemeteries work similarly than urban parks supporting avian diversity. 相似文献
13.
Reclamation usually involves modification of the local environment to achieve some biotic target, but if the influence of
Landscape Condition on that target is great, we may fail to meet it despite efforts at the local-level. We sought to determine
the relative influence of local- and landscape-level habitat on aquatic plant diversity in shallow open-water wetlands. Furthermore,
we asked whether the influence of Landscape Condition should be attributed to direct (dispersal-related) effects, or to the
indirect effect of landscape variables that influence local habitat quality. Finally, we asked if spatial scale (300–2000 m)
would affect conclusions about the relative influence of local- and landscape-level effects. Using structural equation modeling,
we found that Local Condition is consistently more influential than Landscape Condition. As landscape size increases, the
relative importance of Landscape Condition declines and there is a trade-off between its direct and indirect components. At
≤500 m direct landscape effects were of greater importance than indirect effects, whereas indirect effects of Landscape Condition
became more important at ≥1500 m. This suggests that the dominant mechanism by which land use influences diversity depends
on the spatial extent of the landscape. We recommend that reclamation designs include a high proportion of wetland habitat
and incorporate seeding/planting if diverse plant communities are desired. Additionally, we note that the influence of the
landscape is strongest within 300 m. Thus, the focus of reclamation efforts should remain at the in-lake level and the immediate
surroundings: this is where efforts will achieve the greatest effect on aquatic plant diversity. 相似文献
14.
Landscape analysis of plant diversity 总被引：9，自引：0，他引：9
Stohlgren Thomas J. Coughenour Michael B. Chong Geneva W. Binkley Dan Kalkhan Mohammed A. Schell Lisa D. Buckley David J. Berry Joseph K. 《Landscape Ecology》1997,12(3):155-170
Studies to identify gaps in the protection of habitat for speciesof concern have been inconclusive and hampered by single-scale orpoor multi-scale sampling methods, large minimum mapping units(MMU's of 2 ha to 100 ha), limited and subjectively selected fieldobservations, and poor mathematical and ecological models. Weovercome these obstacles with improved multi-scale samplingtechniques, smaller MMU's (< 0.02 ha), an unbiased sampling designbased on double sampling, improved mathematical models includingspecies-area curves corrected for habitat heterogeneity, andgeographic information system-based ecological models. We applythis landscape analysis approach to address resource issues inRocky Mountain National Park, Colorado. Specifically, we quantifythe effects of elk grazing on plant diversity, identify areas ofhigh or unique plant diversity needing increased protection, andevaluate the patterns of non-native plant species on thelandscape.Double sampling techniques use satellite imagery,aerial photography, and field data to stratify homogeneous andheterogeneous units and keystone ecosystems (ecosystems thatcontain or support a high number of species or have distinctivespecies compositions). We show how a multi-scale vegetationsampling design, species-area curves, analyses of within- andbetween-vegetation type species overlap, and geographic informationsystem (GIS) models can be used to quantify landscape-scalepatterns of vascular plant diversity in the Park.The new multi-scale vegetation plot techniques quickly differentiated plantspecies differences in paired study sites. Three plots in the OuzelBurn area (burned in 1978) contained 75 plant species, while only17 plant species were found in paired plots outside the burn.Riparian areas contained 109 plant species, compared to just 55species in paired plots in adjacent forests. However, plant speciesrichness patterns inside and outside elk exclosures were morecomplex. One elk exclosure contained more species than its adjacentopen range (52 species inside and 48 species outside). Two elkexclosures contained fewer species inside than outside (105 and 41species inside and 112 and 74 species outside, respectively).However, there was only 26% to 48% overlap (using Jaccard'sCoefficient) of plant species composition inside and outside theexclosures. One elk exclosure had 13% cover of non-indigenousspecies inside the exclosure compared to 4% outside, butnon-indigenous species cover varied by location.We compared plantdiversity patterns from vegetation maps made with 100 ha, 50 ha, 2ha, and 0.02 ha MMU's in the 754 ha Beaver Meadows study area usingfour 0.025 ha and twenty-one 0.1 ha multi-scale vegetation plots.Preliminary data suggested that the 2 ha MMU provided an accurateestimate of the number of plant species (–14%) for a study area,but the number of habitats (polygons) was reduced by 67%, andaspen, a unique and important habitat type, was missed entirely. Wedescribe a hypothesis-driven approach to the design andimplementation of geospatial databases for local resourcemonitoring and ecosystem management. 相似文献
15.
Urban plant diversity influences the social functioning and well-being of urban dwellers. However, the patterns and drivers of plant diversity in tropical urban areas are still not entirely understood. In response to the knowledge deficiencies in this area, we investigated spontaneous and cultivated plant richness and their phylogenetic diversity and relatedness in 260 Urban Functional Units (UFUs), which represented nine different land use types according to anthropogenic function, in the tropical coastal city of Zhanjiang, China. Plant diversity was modelled as a function of UFU characteristics and human maintenance practices. Spontaneous species richness was highest in urban villages and vacant lands and lowest in transportation areas, while phylogenetic diversity was highest in utilities and lowest in parks. In comparison, cultivated species richness was highest in multi-family residential areas and lowest in vacant lands, while phylogenetic diversity of cultivated species was highest in commercial/industry areas and lowest in agriculture areas. The number of cultivated species and the degree of phylogenetic relatedness of spontaneous species were positively correlated with the human population density. The phylogenetic diversity of cultivated species within UFUs was generally higher than that of spontaneous species. Human maintenance of landscapes acted as an environmental filter for spontaneous species, but also promoted the number of cultivated plants. We conclude that appropriate investment in urban green areas may improve both plant species richness and phylogenetic diversity in urban environments. 相似文献
16.
The effects of habitat fragmentation on species richness and composition have been extensively studied. However, little is known about how fragmentation affects functional diversity patterns. Fragmentation can indeed affect functional diversity directly (e.g. by promoting traits associated to long-distance dispersal when fragment isolation increases) or indirectly (e.g. by decreasing species richness, hence trait diversity, when fragment area decreases). Here, we used structural equation modeling to determine whether factors associated to forest fragmentation, namely area, habitat heterogeneity, spatial isolation and age have a direct effect on forest herb functional diversity. Using occurrence data from 243 forest fragments located in northern France and six plant life-history traits, we estimated species richness and calculated functional diversity in each of these 243 forest fragments. We found that species richness was the primary driver of functional diversity in these fragments, with a strong positive and direct relationship between species richness and functional diversity. Interestingly, both fragment isolation and age had a direct negative effect on functional diversity independent of their effects on species richness. Isolation selected life-history traits associated with long-distance dispersal, while age selected for life-history traits typical of forest habitat specialists. Isolated and/or older forest fragments are thus at greater risk of local species and functional extinctions, and hence making these forest fragments particularly vulnerable to future global changes. 相似文献
17.
Habitat loss and fragmentation of natural and semi-natural habitats are considered as major threats to plant species richness.
Recently several studies have pinpointed the need to analyse past landscape patterns to understand effects of fragmentation,
as the response to landscape change may be slow in many organisms, plants in particular. We compared species richness in continuously
grazed and abandoned grasslands in different commonplace rural landscapes in Sweden, and analysed effects of isolation and
area in three time-steps (100 and 50 years ago and today). Old cadastral maps and aerial photographs were used to analyse
past and present landscape patterns in 25 sites. Two plant diversity measures were investigated; total species richness and
species density. During the last 100 years grassland area and connectivity have been reduced by about 90%. Present-day habitat
area was positively related to total species richness in both habitats. There was also a relationship to habitat area 50 years
ago for continuously grazed grasslands. Only present management was related to species density: continuously grazed grasslands
had the highest species density. There were no relationships between grassland connectivity, present or past, and any diversity
measure. We conclude that landscape history is not directly important for present-day plant diversity patterns in ordinary
landscapes, although past grassland management is a prerequisite for the grassland habitats that can be found there today.
It is important that studies are conducted, not only in very diverse landscapes, but also in managed landscapes in order to
assess the effects of fragmentation on species. 相似文献
18.
Habitat specificity indices reflect richness (α) and/or distinctiveness (β) components of diversity. The latter may be defined by α and γ (landscape) diversity in two alternative ways: multiplicatively () and additively (). We demonstrate that the original habitat specificity concept of Wagner and Edwards (Landscape Ecol 16:121–131, 2001) consists of three independent components: core habitat specificity (uniqueness of the species composition), patch area and
patch species richness. We describe habitat specificity as a family of indices that may include either area or richness components,
or none or both, and open for use of different types of mean in calculation of core habitat specificity. Core habitat specificity
is a beta diversity measure: the effective number of completely distinct communities in the landscape. Habitat specificity
weighted by species number is a gamma diversity measure: the effective number of species that a patch contributes to landscape
richness. We compared 12 habitat specificity indices by theoretical reasoning and by use of field data (vascular plant species
in SE Norwegian agricultural landscapes). Habitat specificity indices are strongly influenced by weights for patch area and
patch species richness, and the relative contribution of rare vs. common species (type of mean). The relevance of properties
emphasized by each habitat specificity index for evaluation of patches in a biodiversity context is discussed. Core habitat
specificity is emphasized as an ecologically interpretable measure that specifically addresses patch uniqueness while habitat
specificity weighted by species number combines species richness and species composition in ways relevant for conservation
biological assessment.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
19.
Elsa Aggemyr Alistair G. Auffret Love Jädergård Sara A. O. Cousins 《Landscape Ecology》2018,33(12):2273-2284
Context
Understanding how landscape patterns affect species diversity is of great importance in the fields of biogeography, landscape ecology and conservation planning, but despite the rapid advance in biodiversity analysis, investigations of spatial effects on biodiversity are still largely focused on species richness.Objectives
We wanted to know if and how species richness and species composition are differentially driven by the spatial measures dominating studies in landscape ecology and biogeography. As both measures require the same limited presence/absence information, it is important to choose an appropriate diversity measure, as differing results could have important consequences for interpreting ecological processes.Methods
We recorded plant occurrences on 112 islands in the Baltic archipelago. Species richness and composition were calculated for each island, and the explanatory power of island area and habitat heterogeneity, distance to mainland and structural connectivity at three different landscape sizes were examined.Results
A total of 354 different plant species were recorded. The influence of landscape variables differed depending on which diversity measure was used. Island area and structural connectivity determined plant species richness, while species composition revealed a more complex pattern, being influenced by island area, habitat heterogeneity and structural connectivity.Conclusions
Although both measures require the same basic input data, species composition can reveal more about the ecological processes affecting plant communities in fragmented landscapes than species richness alone. Therefore, we recommend that species community composition should be used as an additional standard measure of diversity for biogeography, landscape ecology and conservation planning.20.
Homegardens are principally known as integrated man-made ecosystems with annuals and perennials where trees play a significant role in storing atmospheric carbon in the vegetation as above-ground biomass (AGB). Being one of the agroforestry systems, homegardens could ease the pressure on natural forest cover in the process of carbon sequestration and carbon storage, while reducing the greenhouse gas accumulation (CO2) in the atmosphere. Thus, they could be described as a promising approach for mitigation of climatic changes. A study was conducted to assess the tree diversity and AGB carbon stock of homegardens in Matale district, Sri Lanka. A total of 122 homegardens ranging from urban dwellings up to natural eco-systems across 05 agro-ecological regions (AER) were surveyed, capturing a vast diversity. A total of 5140 woody trees were recorded from 100 genera and 45 families, covering 16.67 ha of homegardens. Six and three tree species were identified as vulnerable and near threatened, respectively in terms of national-level conservation status. Shannon-Wiener index (SWI) of 1.90 ± 0.49 ranging between 0.49 and 2.83 indicated compositional diversity of the tree species. The AGB was widely varying between 0.8 and 139.4 Mg C/ha (mean AGB of 36.5 ± 27.4 Mg C/ha). AGB and SWI were higher in small-scale (38.8 ± 29.7 Mg C/ha and 1.91 ± 0.50, respectively) than in medium-scale homegardens (28.0 ± 14.9 Mg C/ha and 1.86 ± 0.50, respectively). Species richness and number of species per hectare were higher in small scale (<0.2 ha) homegardens compared to medium scale (0.2–0.8 ha). A considerable variation of tree diversity and AGB was observed among the homegardens in different AERs. The variation of AGB was primarily governed by tree density (trees/ha) and species diversity. Focusing on that, optimizing the potential of homegardens in terms of storing atmospheric carbon as AGB in the study area can be considered as a timely strategy in mitigating impacts of climate change and assisting domestic food security. 相似文献