不同空间尺度三维建筑景观变化

以沈阳市铁西区建筑物三维信息为基础数据,从建筑高度、密度、体积与体形、分布均匀度与空间拥挤度等方面构建了三维建筑景观评价指标,分别从区域、功能分区和梯度带3个角度分析了三维建筑景观的变化特征.结果表明:从1997年到2008年,铁西区建筑向垂直方向扩张,建筑空间分布越来越不均匀,空间拥挤度、建筑平均体积与容积率逐渐增大;居住区平均高度、平均体积、覆盖率、容积率、空间拥挤程度最小,建筑分布最均匀;商业区除建筑高度变异系数和平均体形系数最小外,其余指标值最大;工业区高度变异系数和平均体形系数最大,空间分布最不均匀;从梯度带上看,建筑使用类型的差异决定了三维建筑景观的变化特征.     

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

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

Contrasting responses of arable spiders to the landscape matrix at different spatial scales

Aim Animal communities can be influenced by the composition of the surrounding landscape through immigration. Depending on habitat preferences, however, the effect of the landscape matrix can be positive or negative and can vary with scale. We tested this idea with arable spiders and tried to infer dispersal distances from relationships between local density and landscape composition at different spatial scales. Location Thirty‐eight landscapes around the cities of Göttingen and Giessen, Germany. Methods Spiders were captured with pitfall traps in one field of winter wheat in each landscape. Landscape composition around the fields was characterized at 11 scales from 95 m to 3 km radius by land‐use mapping and subsequent GIS analysis. Correlation tests were performed between landscape composition and local densities or species richness. Results In both study regions, local species richness was enhanced by non‐crop habitats on a landscape scale. The overall densities of wolf spiders (Lycosidae), long‐jawed spiders (Tetragnathidae), crab spiders (Thomisidae), and dwarf sheet spiders (Hahniidae) increased significantly in landscapes with high percentages of non‐crop habitats. Out of the 40 species tested, 19 responded positively to the percentage of non‐crop habitats in the surrounding landscape, and five responded negatively. Depending on the species, the spatial scales with the highest explanatory power ranged from 95 m to 3 km radius around the study fields, potentially reflecting dispersal distances. Main conclusions Arable spider species showed contrasting responses to the landscape context with respect both to the direction and to the spatial scale of the relationship. The variation in landscape requirements among species ensures high spider densities in a wide range of situations, which contributes to ecosystem resilience. However, species richness of arable spiders depends on heterogeneous landscapes with high percentages of non‐crop habitats.     

不同空间尺度景观特征对南流江水质的影响差异

流域景观特征决定了非点源污染物来源与地表景观削减消纳能力,但尚缺乏全流域不同空间尺度对二者关联性的认识。以广西北部湾南流江为例,分别在子流域、河岸缓冲带以及监测点圆形缓冲区三种尺度上,基于2020年Landsat 8 OLI遥感影像解译的土地利用类型特征,结合水质监测数据,运用数理统计和GIS空间分析方法,探讨了流域景观特征在不同空间尺度上对河流水质的影响。结果表明：(1)在子流域尺度,土地利用类型以林地为主,而在河岸缓冲带与监测点圆形缓冲区均以耕地为主;(2)水质指标高锰酸盐指数、生化需氧量与景观特征相关性最为显著,耕地、建设用地、其他用地和园地与其呈正相关,是南流江水质污染负荷的重要来源区;景观格局指数中,斑块密度、蔓延度指数、多样性指数、均匀度指数是引起河流水质指标变化的主要景观因子;(3)受流域内或不同子流域间景观特征差异,景观组成面积占比和景观格局指数均在河岸缓冲带尺度对水质状况影响最大,分别可解释57.0%和64.7%的水质指标变化;子流域尺度次之,圆形缓冲区尺度最小,且景观格局指数对水质状况的影响大于景观组成面积占比。建议在河岸带50 m范围内严格控制耕地面积,建设河岸缓...     

Site‐specific responses of foliar fungal microbiomes to nutrient addition and herbivory at different spatial scales

The plant microbiome can affect host function in many ways and characterizing the ecological factors that shape endophytic (microbes living inside host plant tissues) community diversity is a key step in understanding the impacts of environmental change on these communities. Phylogenetic relatedness among members of a community offers a way of quantifying phylogenetic diversity of a community and can provide insight into the ecological factors that shape endophyte microbiomes. We examined the effects of experimental nutrient addition and herbivory exclusion on the phylogenetic diversity of foliar fungal endophyte communities of the grass species Andropogon gerardii at four sites in the Great Plains of the central USA. Using amplicon sequencing, we characterized the effects of fertilization and herbivory on fungal community phylogenetic diversity at spatial scales that spanned within‐host to between sites across the Great Plains. Despite increasing fungal diversity and richness, at larger spatial scales, fungal microbiomes were composed of taxa showing random phylogenetic associations. Phylogenetic diversity did not differ systematically when summed across increasing spatial scales from a few meters within plots to hundreds of kilometers among sites. We observed substantial shifts in composition across sites, demonstrating distinct but similarly diverse fungal communities were maintained within sites across the region. In contrast, at the scale of within leaves, fungal communities tended to be comprised of closely related taxa regardless of the environment, but there were no shifts in phylogenetic composition among communities. We also found that nutrient addition (fertilization) and herbivory have varying effects at different sites. These results suggest that the direction and magnitude of the outcomes of environmental modifications likely depend on the spatial scale considered, and can also be constrained by regional site differences in microbial diversity and composition.     

Bark beetle diversity at different spatial scales

To determine how the scale of observation affects ecological patterns we studied bark beetle (Coleoptera, Scolytidae) diversity in southern Finland. A block covering 160 × 160 m of a forest was delimited in four stands of different site types. Each block was divided into 256 squares (10 × 10 m) in which the occurrence of bark beetle species was recorded. In addition, environmental variables describing site type, trees, and breeding material appropriate for bark beetles were measured. The species presence/absence data were combined at different scales of resolution (10 × 10 m. 20 × 20 m, 40 × 40 m, 80 × 80 m, 160 × 160 m). At the finest scale a recently thinned pine stand showed relatively high diversity compared to other study stands due to a few evenly distributed and abundant species. However, the species diversity increased faster toward larger scales in mature spruce stands with several sporadically distributed species. According to logistic regression analyses, breeding material and site characteristics explained the occurrence of most beetle species. However, these variables did not explain the occurrence of the six most frequent species, probably because the factors regulating their distribution and occurrence operate at larger scales.     

Herbivore metabolism and stoichiometry each constrain herbivory at different organizational scales across ecosystems

Plant-herbivore interactions mediate the trophic structure of ecosystems. We use a comprehensive data set extracted from the literature to test the relative explanatory power of two contrasting bodies of ecological theory, the metabolic theory of ecology (MTE) and ecological stoichiometry (ES), for per-capita and population-level rates of herbivory across ecosystems. We found that ambient temperature and herbivore body size (MTE) as well as stoichiometric mismatch (ES) both constrained herbivory, but at different scales of biological organization. Herbivore body size, which varied over 11 orders of magnitude, was the primary factor explaining variation in per-capita rates of herbivory. Stoichiometric mismatch explained more variation in population-level herbivory rates and also in per-capita rates when we examined data from within functionally similar trophic groups (e.g. zooplankton). Thus, predictions from metabolic and stoichiometric theories offer complementary explanations for patterns of herbivory that operate at different scales of biological organization.     

Modelling bird habitat suitability based on landscape parameters at different scales

Habitat suitability as characterized by the presence of a species and by reproductive success was modelled in relation to different parameters of landscape diversity at different scales. Parameters characterizing landscape pattern were determined for the UTM 10 km × 10 km cells covering the whole of Estonia and were correlated to the distribution of over 30 forest bird species. The landscape parameters include areas of lakes, mires and built-up areas, length of borders between different land cover units and length of selected line elements, share of different kinds of forest and peatland. The bird species are grouped by correlation into three major groups: (a) independent, (b) wetland preferring (with subgroups of those avoiding built-up areas and roads and those not) and (c) built-up area dependent (with subgroups depending on the importance of line elements). For selected predator species, nesting success was related to landscape parameters on a finer scale, using cells of 10 km². Land pattern was characterized by total length of line elements (streams, roads, borders, ecotones) and certain areal coverage (forest, mires, fields, built-up areas) within the cell. The impact of variations of food availability was linked to the relation. Possibilities for downscaling and upscaling of relations determined at different scales and areal coverage are discussed.     

Interactions of gall-forming species at different plant spatial scales

Interspecific competition has been intensely studied as an organizing force in insect herbivore communities that can be mediated by changes in resource availability. We analyzed patterns of interspecific association of three species of gall-forming insects at shoot length class and shrub levels for Bauhinia brevipes through a null model program. Results show that shoots galled by three species were distributed independently among shoot length classes over 3-years, hence, no evidence of competition for shoots was found. Nevertheless, at the plant level our results suggest that there was a positive association. We found no evidence of any reciprocal negative effect because the density of species did not differ among shoot length classes. We suggest that this lack of pattern was probably due to: (a) host-plant resistance mediating interactions; (b) higher abundance of plant resource available, or (c) free-feeding herbivores mediating interactions by manipulating the resources used by gall-forming species.     

Determinants of avian species richness at different spatial scales

ABSTRACT. Studies of factors influencing avian biodiversity yield very different results depending on the spatial scale at which species richness is calculated. Ecological studies at small spatial scales (plot size 0.0025–0.4 km²) emphasize the importance of habitat diversity, whereas biogeographical studies at large spatial scales (quadrat size 400–50,000 km²) emphasize variables related to available energy such as temperature. In order to bridge the gap between those two approaches the bird atlas data set of Lake Constance was used to study factors determining avian species diversity at the intermediate spatial scales of landscapes (quadrat size 4–36 km²). At these spatial scales bird species richness was influenced by habitat diversity and not by variables related to available energy probably because, at the landscape scale, variation in available energy is small. Changing quadrat size between 4 and 36 km², but keeping the geographical extension of the study constant resulted in profound changes in the degree to which the amount of different habitat types was correlated with species richness. This suggests that high species diversity is achieved by different management regimes depending on the spatial scale at which species richness is calculated. However, generally, avian species diversity seems to be determined by spatial heterogeneity at the corresponding spatial scale. Thus, protecting the diversity of landscapes and ecosystems appears to ensure also high levels of species diversity.     

Grains of connectivity: analysis at multiple spatial scales in landscape genetics

Landscape genetic analyses are typically conducted at one spatial scale. Considering multiple scales may be essential for identifying landscape features influencing gene flow. We examined landscape connectivity for woodland caribou (Rangifer tarandus caribou) at multiple spatial scales using a new approach based on landscape graphs that creates a Voronoi tessellation of the landscape. To illustrate the potential of the method, we generated five resistance surfaces to explain how landscape pattern may influence gene flow across the range of this population. We tested each resistance surface using a raster at the spatial grain of available landscape data (200 m grid squares). We then used our method to produce up to 127 additional grains for each resistance surface. We applied a causal modelling framework with partial Mantel tests, where evidence of landscape resistance is tested against an alternative hypothesis of isolation-by-distance, and found statistically significant support for landscape resistance to gene flow in 89 of the 507 spatial grains examined. We found evidence that major roads as well as the cumulative effects of natural and anthropogenic disturbance may be contributing to the genetic structure. Using only the original grid surface yielded no evidence for landscape resistance to gene flow. Our results show that using multiple spatial grains can reveal landscape influences on genetic structure that may be overlooked with a single grain, and suggest that coarsening the grain of landcover data may be appropriate for highly mobile species. We discuss how grains of connectivity and related analyses have potential landscape genetic applications in a broad range of systems.     

Conservation planning with insects at three different spatial scales

Deciding which areas to protect, and where to manage and how, are no easy tasks. Many protected areas were established opportunistically under strong political and economic constraints, which may have resulted in inefficient and ineffective conservation. Systematic conservation planning has helped us move from ad-hoc decisions to a quantitative and transparent decision-making process, identifying conservation priorities that achieve explicit objectives in a cost-efficient manner. Here we use Finnish butterflies to illustrate different modeling approaches to address three different types of situations in conservation planning at three different spatial scales. First, we employ species distribution models at the national scale to construct a conservation priority map for 91 species at the resolution of 10×10  km. Species distribution models interpolate sparse occurrence data to infer variation in habitat suitability and to predict species responses to habitat loss, management actions and climate change. Second, at the regional scale we select the optimal management plan to protect a set of habitat specialist species. And third, at the landscape scale, we use a metapopulation approach to manage a network of habitat patches for long-term persistence of a single butterfly species. These different modeling approaches illustrate trade-offs between complexity and tractability and between generality and precision. General correlation-based models are helpful to set priorities for multiple species at large spatial scales. More specific management questions at smaller scales require further data and more complex models. The vast numbers of insect species with diverse ecologies provide a source of information that has remained little used in systematic conservation planning.     

Community structure in ichneumonid parasitoids at different spatial scales

The processes underlying parasitoid community structure are little known. Stochastic niche-apportionment models provide one route to underlying assemblage rules in this and other groups. Previous work has applied this approach to parasitoids found on single host species in single populations. However, parasitoid communities are known to extend across multiple hosts and scales. The patterns of relative abundances generated by five niche-apportionment models were compared to those observed in assemblages of two sub-families of the Ichneumonidae, the Diplazontinae and Pimplinae, at landscape and patch scales, Yorkshire, UK. Three of the five models produced patterns that were significantly different to the observed pattern for all taxonomic levels at both spatial scales. The Diplazontinae fit the random fraction (RF) model at the landscape scale in broadleaved woods. This suggests that hierarchical structuring and biotic interactions may play a role in the structuring of Diplazontinae assemblages at this scale. In contrast the Pimplinae fit the RF model only at the patch scale and only at one site. However, the Pimplini tribe (all chiefly parasitoids of Lepidoptera) fit the random assortment (RA) model at both the landscape and the patch scales, whilst the Ephialtini tribe (wide range of hosts) fit no model at either scale. The ecological interpretation of the RA model suggests that the Pimplini tribe is an unsaturated assemblage, where some of the total available resources are unused. Our results show, through the fit of mechanistic niche-apportionment models, that the processes that may structure ichneumonid parasitoid assemblages are not consistent across taxa and spatial scales.     

Habitat fragmentation determines diversity of annual plant communities at landscape and fine spatial scales

The aim of this study was to disentangle the effects of landscape configuration (i.e., fragment area, connectivity, and proximity to a busy highway) on the assembly of annual plant communities at different spatial scales. Our main hypothesis was that larger and more connected fragments would have higher species densities per plot and this may result in differences in turnover and nestedness patterns at the fine spatial scales where plants interact. Specifically, since Mediterranean annuals are known to form strong competitive hierarchies, we expected to find a nested pattern of beta diversity due to sequential species loss. The study area was a fragmented gypsum habitat in central Spain with a semiarid climate where two fragmentation drivers coexist: agricultural practices and a roadway. Larger fragments had higher species densities per plot (20 × 20 m). Nevertheless, we detected no effect on the species assembly at fine spatial scales (30 × 30 cm). However, when the fragment connectivity was high the species that appeared in poor quadrats (30 × 30 cm) comprised a subset of the species in rich quadrats. These results agree well with the establishment of strong competitive hierarchies among annual species. The distance to the highway influenced the identity of the species established in the community (i.e., species composition) at fine spatial scales, but we detected no effect on species turnover, nestedness, or species densities. The main conclusion of our study is that the effects of habitat fragmentation extend beyond the landscape scale and they determine the spatial assembly at fine spatial scales.     

Impacts of a pesticide on pollinator species richness at different spatial scales

Pesticides are an important potential cause of biodiversity and pollinator decline. Little is known about the impacts of pesticides on wild pollinators in the field. Insect pollinators were sampled in an agricultural system in Italy with the aim of detecting the impacts of pesticide use. The insecticide fenitrothion was over 150 times greater in toxicity than other pesticides used in the area, so sampling was set up around its application. Species richness of wild bees, bumblebees and butterflies were sampled at three spatial scales to assess responses to pesticide application: (i) the ‘field’ scale along pesticide drift gradients; (ii) the ‘landscape’ scale sampling in different crops within the area and (iii) the ‘regional’ scale comparing two river basins with contrasting agricultural intensity. At the field scale, the interaction between the application regime of the insecticide and the point in the season was important for species richness. Wild bee species richness appeared to be unaffected by one insecticide application, but declined after two and three applications. At the landscape scale, the species richness of wild bees declined in vine fields where the insecticide was applied, but did not decline in maize or uncultivated fields. At the regional scale, lower bumblebee and butterfly species richness was found in the more intensively farmed basin with higher pesticide loads. Our results suggest that wild bees are an insect pollinator group at particular risk from pesticide use. Further investigation is needed on how the type, quantity and timing of pesticide application impacts pollinators.