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1.
Species distribution models are often used to study the biodiversity of ecosystems. The modelling process uses a number of parameters to predict others, such as the occurrence of determinate species, population size, habitat suitability or biodiversity. It is well known that the heterogeneity of landscapes can lead to changes in species’ abundance and biodiversity. However, landscape metrics depend on maps and spatial scales when it comes to undertaking a GIS analysis.We explored the goodness of fit of several models using the metrics of landscape heterogeneity and altitude as predictors of bird diversity in different landscapes and spatial scales. Two variables were used to describe biodiversity: bird richness and trophic level diversity, both of which were obtained from a breeding bird survey by means of point counts. The relationships between biodiversity and landscape metrics were compared using multiple linear regressions. All of the analyses were repeated for 14 different spatial scales and for cultivated, forest and grassland environments to determine the optimal spatial scale for each landscape typology.Our results revealed that the relationships between species’ richness and landscape heterogeneity using 1:10,000 land cover maps were strongest when working on a spatial scale up to a radius of 125–250 m around the sampled point (circa 4.9–19.6 ha). Furthermore, the correlation between measures of landscape heterogeneity and bird diversity was greater in grasslands than in cultivated or forested areas. The multi-spatial scale approach is useful for (a) assessing the accuracy of surrogates of bird diversity in different landscapes and (b) optimizing spatial model procedures for biodiversity mapping, mainly over extensive areas.  相似文献   

2.
Community structure is expected to be affected by spatial heterogeneity in a landscape. We examined the spatial-scale-dependent effects of windthrow caused by a large typhoon on a forest bird community. Typhoon events of this magnitude are rare in Hokkaido, Japan, occurring only once or twice a century. To assess the “functional spatial scale” at which bird groups (community, species, body-size class, and foraging guild) specifically responded to landscape heterogeneity, the canopy gap rate (CGR, gap percentage) was evaluated at different spatial scales by varying the radius of a circular landscape sector from 100 to 500 m stepwise by 10 m. We then analysed bird community responses, in terms of species richness and abundance, to CGR. Bird species richness did not significantly depend on CGR. In contrast, abundance was significantly dependent on CGR in many groups (species, body-size class, and foraging guild). The guild-level response was clearer than the species-level response, which suggests that the integration and filtration of species traits by guild can reveal a clear response of bird abundance to the extent of canopy gaps. For example, the scale dependence of responses to disturbance clearly varied among body-size classes, where larger birds had larger functional spatial scales. These results reveal that different groups of organisms have different functional spatial scales at which they respond to habitat heterogeneity. Our results also suggest that monitoring only a small number of species could be misleading for conserving biodiversity at the landscape level.  相似文献   

3.
The conservation of biodiversity has gained prominence in ecological research for the last decades. Conservation actions require a measure of biodiversity such as species richness, but its assessment is very difficult, even for small areas and therefore the search for surrogates (i.e. indicators) of biodiversity has emerged as an active research topic. We investigated the relationships between butterfly species richness and landscape structure and composition in two pine plantation sites in Southwest France. We assessed the correlation between butterfly species richness and a set of 15 landscape metrics computed for 18 land-uses at 10 different spatial scales. Spatial scales were accounted for by computing landscape metrics for circular buffers with radius ranging from 100 to 1000 m. The joint use of the Partial Least Squares Regression (PLSR) and a stepwise regression procedure revealed strong correlations between butterfly species richness and various landscape metrics in both study sites. The selected landscape metrics differed from one site to another and mostly involved measures of landscape fragmentation. We found a very strong effect of the spatial scale of investigation upon the perception of the landscape–butterfly richness relationship. Our main conclusions are that (i) certain landscape attributes can potentially serve as indicators for butterfly species richness at the landscape scale; (ii) future indicators of biodiversity based on landscape features should consider various spatial scales.  相似文献   

4.
Different approaches for the assessment of biodiversity by means of remote sensing were developed over the last decades. A new approach, based on the spectral variation hypothesis, proposes that the spectral heterogeneity of a remotely sensed image is correlated with landscape structure and complexity which also reflects habitat heterogeneity which itself is known to enhance species diversity. In this context, previous studies only applied species richness as a measure of diversity. The aim of this paper was to analyze the relationship of richness and abundance-based diversity measures with spectral variability and compare the results at two scales. At three different test sites in Central Namibia, measures of vascular plant diversity was sampled at two scales – 100 m2 and 1000 m2. Hyperspectral remote sensing data were collected for the study sites and spectral variability, was calculated at plot level. Ordinary least square regression was used to test the relationship between species richness and the abundance-based Shannon Index and spectral variability. We found that Shannon Index permanently achieved better results at all test sites especially at 1000 m2, Even when all sites where pooled together, Shannon Index was still significantly related with spectral variability at 1000 m2. We suggest incorporating abundance-based diversity measures in studies of relationships between ecological and spectral variability. The contribution made by the high spectral and spatial resolution of the hyperspectral sensor is discussed.  相似文献   

5.
The endemic avifauna of Wallacea is of high conservation significance, but remains poorly studied. Identifying priority conservation areas requires a greater understanding of the habitat associations of these bird communities, and of how spatial scale of analysis can influence the interpretation of these associations. This study aims to determine which proxy habitat measures, at which spatial scales of analysis, can provide useful inferential data on the composition of Wallacean forest avifauna. Research was conducted within the Lambusango forest reserve, South-East Sulawesi, using point count surveys to sample avifauna. Habitat properties were characterised in three ways: broad classification of forest type, canopy remotely-sensed response derived from satellite imagery, and in situ measures of vegetation composition and structure. Furthermore, we examined avifauna–habitat relationships at three spatial scales: area (c.400 ha per sample site), transect (c.10 ha) and point (c.0.2 ha). Results demonstrate that broad forest type classifications at an area scale can help to determine conservation value, indicating that primary and old secondary forests are important for supporting many species with lower ecological tolerances, such as large-bodied frugivores. At the transect-scale, significant congruence occurs between bird community composition and several habitat variables derived from vegetation sampling and satellite imagery, particularly tree size, undergrowth density, and Normalised Difference Vegetation Index (NDVI) values; this highlights the importance small scale habitat associations can have on determining α-diversity. Analysis at the point-scale was ineffective in providing proxy indications for avifauna. These findings should be considered when determining future priority conservation areas for Wallacean avifauna.  相似文献   

6.
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.  相似文献   

7.
8.
Nature conservation and restoration activities require delineation of effective conservation networks. This paper presents a methodology which allows a quick evaluation of different planning options for extensive areas. We analyzed the spatial structure of remaining patches of the natural Cerrado vegetation in the Balsás sub-basin, South of Maranhão State of Brazil (about 25,590 km2) in order to understand how the remaining habitats are distributed and spatially configured. Conservation area network scenarios are based on hexagonal cells, referred to as analysis unit (AU) cells. A multi-scale analysis of 10,000 ha and 50,000 ha AU cells was set up to represent local and regional scales, respectively. For each AU at both local and regional scales we computed landscape metrics of native vegetation: NATIVE VEGETATION COVER: percentage of native vegetation cover; (NV-NP): number of patches; (NV-MSI): mean shape index. Subsequently, five different conservation and restoration strategies were defined: (a) only enforce nature conservation within legally established units; (b) target nature conservation only within the local AU landscape; (c) target regional management by combining neighboring AU; (d) management of both local landscape and region; (e) protect the legal conservation areas and promote local and regional conservation. We also generated scenarios of habitat capacity for mammals and matched these results with the different vegetation conservation scenarios. Results indicate that only 12% of the study area is well conserved and that 43% of the region is in a very critical condition. The percentage of AU cells where native vegetation conservation actions are required differ for the five conservation strategies: These results allow policy makers and other stakeholders to target the locations and extent of conservation units required. We suggest that about 45% of the sub-basin could be managed at local, regional or both scales. Regarding a mammal species diversity scenario an even higher percentage of the average habitat capacity of the selected species occurs in open cerrado and valleys areas that coincide with critical areas. The proposed multi-scale analysis unit cell approach can support the planning process of extensive areas as necessary in Brazil.  相似文献   

9.
Community concordance within aquatic biota could provide useful information for improving the methods used in bioassessment and biodiversity conservation management. The main goal of the study was to investigate the mechanism of community concordance between macroinvertebrates and fish in a single river basin (South Morava river Basin, Serbia). In order to achieve this, a Self organizing map (SOM) ordinated and classified sampling sites based on the community structures of five different taxa groups (macroinveretbrates (MIB), fish (FSH), Chironomidae (CHI), Macroinvertebrates without Chironomidae (MWC) and the Ephemeroptera Plecoptera Trichioptera group (EPT)). SOM also revealed 6 environmental gradients along the groups tested that significantly changed their community structures. Using the results of the SOM analysis as the input, the Mantel test quantified the highest community concordance between FSH and MIB (r = 0.42) followed by FSH and CHI (r = 0.29). The lowest concordance was recorded between FSH and EPT (r = 0.14). The indicator species analysis (IndVal) revealed 39 species to be responsible for the community patterns obtained. The Geo-SOM visualized the spatial distribution of the IndVal taxa, revealing the generators of community concordance. The strength of community concordance depends on the variability of the data on the aquatic biota. Thus, having an appropriate sampling and statistical design as well as high taxonomic resolution, as some of the factors which increase the variability in the data set, could present community concordance between fish and macroinvertebrates in an unbiased way.  相似文献   

10.
It has recently been stated that the global goal of halting the loss of biodiversity by 2010 has not been met highlighting the urgent need to monitor trends in biodiversity. Our study suggests that existing indicators of bird biodiversity in Denmark are inaccurate and we present a new objective method for accurately assessing trends in specific habitats using common bird species. Bird species were selected for creating habitat specific indicators by calculating their relative habitat use (RHU) in nine different habitat categories. RHU indicates the degree to which a habitat is preferred (RHU > 2) or avoided (RHU < 0.5) by a species, relative to other habitats. Indicator sets were constructed for each habitat type using species with an RHU > 2 and revealed that existing habitat indicators, based on species lists from the Pan-European Common Bird Monitoring Scheme (PECBMS), often included species that did not in fact have preferences for those particular habitats in Denmark. Habitat specific indicators based on the new species selection method showed significant negative trends in three of nine habitat categories: coniferous forest, bog/marsh and heath. Habitat classes were further combined to create overall indicators for forest, farmland and freshwater. A comparison of these indicators with the existing indicators revealed a negative overall trend for forest habitat, which had previously been overlooked, suggesting that species selection is crucial for the development of informative indicators. The habitat specific farmland indicator confirmed the negative trend in the current farmland indicator. The methodology for indicator species selection presented here could potentially be applied for use in a global context for a wider range of taxonomic groups.  相似文献   

11.
12.
Protected areas (that are usually designated) play an important role in the effort to halt on-going losses of biodiversity. However, areas outside of designated sites for protection can also hold important elements of biodiversity, and knowledge of their distribution is necessary to ensure effective conservation strategies. We collated and mapped vascular plant distribution data for species of conservation concern on the island of Ireland. For the first time in Ireland, we extracted 6078 distribution records of 176 species of conservation concern and mapped them at the tetrad (2 km × 2 km) scale. We examined the extent to which tetrads with records of species of conservation concern overlapped with designated areas (Natura 2000, Natural Heritage Areas, Areas of Special Scientific Interest). A conservative estimate suggests that many of these tetrads do not overlap with designated areas (in the range of 22–40% for available records). The coincidence of records of individual species with designated areas ranged from 0% to 100% (mean = 79%). The mapped distribution data for all vascular plant species offers guidance to where additional recording may be helpful in supporting conservation activities. The analysis of the distribution of species of conservation concern indicates the importance of both designated areas and the (non-designated) wider countryside for biodiversity conservation. In particular the presence of species of conservation concern in non-designated areas highlights the need for conservation measures outside of designated areas.  相似文献   

13.
《Acta Oecologica》2006,29(1):9-15
Broad-scale correlations between species richness and human population suggest that processes driving species richness, mainly related to high ecological productivity, may also drive human populations. However, it is still under debate if this coincidence implies conflicts between biodiversity conservation and human development. In this paper, we analyzed the relationships among human population size, species richness and irreplaceability in Brazilian Cerrado. We analyzed a dataset with 131 species of anurans distributed in 181 cells with 1° of spatial resolution covering the biome. We found a positive correlation between human population size and anuran species richness (r = 0.46; P = 0.033 with 19.5 geographically effective degrees of freedom, v*), but the irreplaceability of each cell was poorly correlated with human population size (r = 0.075; P = 0.323; v* = 173.9). The 17 cells in the 97 optimal reserve networks contained a total human population ranging from 2942,195 to 4319,845 people, representing on average 11.8% of the human population in the entire Cerrado grid. The comparison of these observed values with 10,000 values from randomly generated networks suggests a relatively high flexibility in optimal complementarity sets for reserve selection. Our results indicated that correlation between richness and human population does not necessarily result in conflicts, given the opportunities for conciliating conservation and development. However, the analyses performed here are initial explorations within the framework of conservation biogeography, so more detailed studies are necessary to establish conservation planning at regional and local scales.  相似文献   

14.
Lake Chaohu is one of the most eutrophic lakes in China. Research on this lake's seasonal and spatial variations in phytoplankton diversity is needed to understand the distribution of eutrophication, as well as to find appropriate comprehensive biodiversity indices to assess the eutrophication status of the lake. The present study indicated that the Margalef index of all samples was as low as 0.799 ± 0.543 in summer (August 2011) and as high as 1.467 ± 0.653 in winter (February 2012). The Margalef index of the river samples had a high mean value and substantial variation compared with the lake samples. The Peilou index of the lake samples was higher than that of the river samples in summer and autumn (November 2011) but lower than that of the river samples in winter. In spring (May 2012), the Peilou index of the western samples was lower than that of the eastern samples. The spatial distribution of the Shannon–Wiener index was more similar to that of the Peilou index in autumn and winter, while in spring and summer, the spatial distribution was affected by both species richness and evenness. High eutrophication levels occurred in the western lake in spring and summer, whereas high levels occurred in the eastern lake, especially in the middle of the lake, in autumn and winter. The total trophic state index (TSI) in all samples exhibited a significant negative correlation with the Margalef (r = −0.726) and Peilou (r = −0.530) indices but a significant positive correlation with the Shannon–Wiener (r = 0.654) index. The partial correlation analysis results implied that these phytoplankton biodiversity indices could serve as synthetic ecological indicators to assess the eutrophication condition of Lake Chaohu.  相似文献   

15.
In most species of vertebrates, teeth play a central role in the long-term performance of individuals. However, patterns of tooth development have been little investigated as an indicator of animal performance. We filled this gap using data collected during long-term capture-mark-recapture monitoring of 1152 roe deer fawns at Chizé, western France. This population fluctuated greatly in size during the 27 years of monitoring, offering a unique opportunity to assess how the eruption patterns of front teeth perform as indicator of animal performance. We used three indices of the eruption of permanent front teeth, the simplest being whether or not incisor I2 has erupted, and the most complex being a 12-level factor distinguishing the different stages of tooth eruption. We also assessed the relevance of these indices as compared to fawn body mass, a widely used indicator of animal performance of deer populations. Dental indices and body mass were positively correlated (all r > 0.62). Similarly to body mass, all indices based on tooth eruption patterns responded to changes of population size and can be reliably used to assess the relationship between roe deer and their environment. We found a linear decrease in body mass with increasing population size (r2 = 0.54) and a simultaneous delay in tooth development (r2 = 0.48–0.55 from the least to the most accurate indicator). However, tooth development would be not further delayed in years with the highest densities (>15 adult roe deer/100 ha). A path analysis supported the population density effect on tooth eruption patterns being mainly determined by the effect of population size on body mass. Our study provides managers with simple indices (e.g., presence-absence of I2) that provide a technically more easy way to standardize measurements of deer density-dependent responses over large geographical and temporal scales than would be possible with body mass.  相似文献   

16.
Because of limitation of manpower, funding, and land available in conservation, the problem of how to select essential regions to establish protection systems for biodiversity maintenance has been widely discussed. In an effort to address the problem, this study has aimed to select a set of priority areas and to determine their priority order by quantifying human disturbances for each area in the Yangtze River Basin (YRB). This basin covers 2.143 million km2, or more than 20% of China's territory. The habitats of 627 indicator species were predicted as a proxy for biodiversity. A conservation planning tool, MARXAN, was used to determine the optimal set of planning units, and three different target scenarios were generated. In addition, under the assumption that if two areas have equal value for conservation, the one suffering more severe disturbance needs more urgent protection than the other, priority ranking analysis was carried out using a 6-12-1 BP artificial neural network. Then hierarchical cluster analysis was applied to the classifications of human disturbances to formulate more detailed conservation strategies. By integrating the degree of irreplaceability of each unit, expert experience, and mountain boundaries, 17 biodiversity priority areas containing 33,200 units over an area of 0.83 million km2 were defined. These areas also protected 56% of 32 types of rare forest ecosystem and 76.4% of six types of rare grassland ecosystem on average. According to the evaluation of human impact, a priority order and five types of human disturbance areas were generated. Some protection gaps were also identified, such as the northern part of the Wuyi Mountains. Moreover, the determination of priority nature conservation areas on a large scale can be used to influence the building of a well-connected protection network in each individual area, so that effective genetic communication can occur between species or groups of species. Conservation decisions focusing on the dominant impact factors that are threatening biodiversity sustainability are required as well.  相似文献   

17.
This review critically evaluates indicators of tidal wetland condition based on 36 indicator development studies and indicators developed as part of U.S. state tidal wetland monitoring programs. Individual metrics were evaluated based on relative scores on two sets of evaluation factors. A rigor score evaluated metric development based on conceptual relevance, indicator development method, degree of independent validation, and temporal and spatial extent tested. An applicability score evaluated metrics based on cost of data collection, probable spatial extent of applicability, technical complexity, and indicator responsiveness. The majority of indicators could be classified as biotic condition indicators (81%), with vegetation (37%) and macroinvertebrate (28%) metrics composing the largest proportion. Most metrics provided a conceptual model or scientific justification (97%), were developed by correlation to environmental gradients (46%), were tested over multiple seasons or years (49%) and at multiple sites (88%). Few were independently validated (18%). Average rigor score was 10 (on a scale of 0–25) and ranged between 1 and 21. Highest rigor scores were for trematode community metrics (community similarity index, species richness) and metrics of grass shrimp (Palaemonetes pugio) individuals (gene expression, relative fecundity, embryo hatching success, larval survival). Most metrics had a high cost of data collection (63%), required field and laboratory processing (84%), would be applicable across the U.S. (72%), and were responsive to the variable of interest (44%). Mean applicability score was 4.9 (range: 2–8). Highest scores were found for metrics that only required field collection of data using simple or no instrumentation. Lowest scoring metrics required expensive equipment, specialized taxonomic knowledge, complex laboratory analysis, and/or culturing of organisms. Scores for individual metrics were grouped by indicator, then averaged and rescaled between 0 and 100 to provide a composite evaluation of the indicator they measured. Among major indicator types, biotic indicators had the highest rigor scores (mean = 44, range 20–79), followed by indicators of chemical/physical characteristics (mean = 36, range 16–56), landscape condition (mean = 31, range 24–37), and hydrology/geomorphology indicators (mean = 21, range 4–52). In contrast, biotic indicators scored lowest for applicability (mean = 58, range 25–100) and indicators of landscape condition scored highest. The results of this review suggest that the development and selection of tidal wetland indicators could be vastly improved by employing a standardized development methodology that provides uniform information about each indicator. In addition, tidal wetland indicator research should focus on the development of indicators of ecological processes and disturbance regimes.  相似文献   

18.
The Western Prairie Fringed Orchid (Platanthera praeclara) is a threatened species found on the Sheyenne National Grassland (SNG) in southeast North Dakota, USA. The SNG is subject to management for multiple uses including biodiversity conservation, livestock grazing and recreation. Therefore, there is a need for the development of indicators of suitable orchid habitat. The orchids are continuously monitored, but understanding of the relationship between landscape properties and orchid locations is limited. In this study data that characterize topography, moisture, and groundwater were used to construct indicators of landscape suitability and an overall Habitat Suitability Index (HSI) for the orchid. A LiDAR-derived DEM and groundwater well observations were used to develop landscape indicators. The Topographic Wetness Index (TWI: a measure of moisture on the landscape), the Topographic Position Index (TPI: a measure of position on the landscape), and the distance to groundwater (DTG: a measure of the distance from the land surface to the groundwater surface) provided the best set of indicators of orchid habitat. Point-based field observations of orchid occurrence were used to develop Orchid Suitability Metrics (OSMs) that identified the range of indicator values most strongly associated with orchids. These OSMs were used to define year by year suitability zones for each indicator that were combined to create the HSI. Comparison of orchid locations with groundwater elevations showed that orchids occurred on average 0.98 ± 0.39 (2σ) m above the water table. TWI and TPI demonstrated that orchids occur near flow paths and areas of lower elevation than their surroundings. HSI values of 0.67 and above were associated with 89.8% of all orchid observations used in the analysis. The landscape indicators, OSM concept and HSI could be generally applied to monitoring and conservation management of orchid habitat and the concept may be applicable to other valued species with similar niche properties.  相似文献   

19.
20.
The abandonment of traditional anthropogenic activities is an important driver shaping landscape patterns. Therefore, multi-scale pattern analysis over time is needed to identify appropriate scales for biodiversity conservation and monitoring of abandoned landscapes. We compared spatial and temporal changes in a pair of alpine watersheds in Italy (Cajada and Tovanella), which are similar in size, geo-climatic conditions, and land-use histories; but have had divergent anthropogenic abandonment processes since the 1950s. We hypothesize that this divergence has led to corresponding dissimilarities in multi-scale patterns of landscape change. To examine this hypothesis, we analyzed land cover maps from three years (1954, 1980/83, 2006) and described the changes using transition matrices. For each year and watershed, landscape heterogeneity and a set of class-level metrics (i.e. percentage of the landscape, area-weighted mean patch size, patch density, area-weighted mean shape index, edge density, and aggregation index) were also measured at different scales using random sampling techniques, and the results were summarized by using scalograms. Woodland expansion occurred mainly at the expenses of grasslands, meadows, and shrublands. These changes were greater during the first time-period (1954-80/83) than in the more recent period (1980/83-2006), with a mean annual value that decreased from +5.18 to +1.33 ha/year and from +4.08 to +1.96 ha/year in the abandoned and managed watersheds, respectively. Landscape heterogeneity decreased over time with a similar pattern in both watersheds, which indicates a general process of homogenization. Management regime affected the spatial-scale response of class-level metrics; these metrics showed a variety of multi-scalar responses, which were not always consistent over time and under different management regimes. When considering the response of the indices across spatial-scales for both watersheds, certain historical curves showed a scale break, representing a significant change in the shape and slope of the curve (i.e. scale divergence). The presence of scale breaks in the scalograms can potentially reveal important thresholds for biodiversity. For example, grassland and meadow patch density at small spatial scales (<200 m radius), which was found to be important for protected butterfly species, had a greater reduction over time in the managed watershed when compared to the abandoned watershed. In conclusion, the findings of this study indicate that there is good potential for understanding changes in landscape patterns under different management abandonment regimes by combining spatial and temporal analysis of class-level metrics.  相似文献   

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