Physio-climatic classification of South Africa's woodland biome

In an effort to develop more holistic ecosystem approaches to resource assessment and management, landscapes need to be stratified into homogeneous geographic regions. These regions can then be used in a monitoring framework to develop reliable estimates of ecosystem productivity. A regional characterization of the woodland biome has been developed for South Africa, delineated by satellite imagery and using environmental data and a rigorous statistical methodology. Distribution maps of key environmental variables are analyzed by factor analysis, an iterative clustering technique and maximum likelihood classification to quantify and identify homogeneous physio-climatic units.A spatial clustering technique was used to identify regions, which are statistically different with regard to five physiographic, climatic and edaphic variables deemed important within southern African savanna woodlands. The woodland biome of South Africa at 1km resolution was successively divided. Thirty year mean monthly temperature, total plant-available water balance of soil, elevation, landscape topographic position, and landscape soil fertility were used as input classification variables.The map data were submitted to a factor analysis and varimax axis rotation. The factor analysis removes correlations from the input variables, reduces the dimensionality, and normalizes the axis measurements. A cluster analysis was performed on the three principal factor scores using a modified iterative optimization clustering procedure to determine the finest level of classes statistically permitable. Twenty-seven identified unimodal cluster signatures were then submitted to a maximum likelihood classification where the statistical probability of the GIS cell assignment is carried out to determine class membership. The final map of custom physio-climatic regions is described, and these custom regions are compared with a vegetation potential map of the woodland types identified in the South African summer rainfall zone.     

The exotic mammals of Argentina

Exotic mammals in South America represent about 20% of world mammal introductions. The aim of our paper is to provide a global assessment of the exotic mammals of Argentina, their pathways, impacts, and a synthesis of their attributes as potential invasive species. We reviewed and compiled data from a diversity of sources and databases on alien mammals occurring in feral state exclusively. We recorded 18 species of exotic mammals for Argentina. The majority of introductions occurred between the 18th and 19th centuries and their ports of entry were located in temperate ecosystems, between 34° and 55° SL. Most of their entry pathways were associated with human activities (e.g. sport hunting, food and fur industry). The exotic mammals occupy ecoregions similar to their original distributions, but most of them have experienced a range expansion to novel habitats. The fauna of exotic mammals of Argentina represents a good opportunity to understand the dynamics of the invasion process as they represent a diversity of ecological groups and environmental contexts.     

Representation of Andean Dry Ecoregions in the Protected Areas of Bolivia: The Situation in Relation to the New Phytogeographical Findings

Bolivia is a megadiverse country. A large part of its biodiversity is due to the fact that in its territory different biogeographical regions meet. As a preliminary means to understand how this biodiversity is being protected, three previous studies undertook an evaluation of how well represented the ecological regions were in the National System of Protected Areas (NSPA). However, the most recent biogeographical findings in Bolivia call for a new analysis of this sort. We try to achieve this, emphasizing the situation in the Andean dry regions, which have been given scarce priority, despite their high biological value. In general, xeric ecoregions are under-represented while humid ones are over-represented. The Prepuna and the central altiplano (which includes the Dry Puna sub-ecoregion) are not represented within the NSPA, nor is the Beni Cerrado sub-ecoregion. The Inter-Andean Dry Valleys cover only ca. 0.5% of the protected area, in spite of their diverse flora and status as one of Bolivia’s most important centers or endemism. Although the diverse Chiquitos Dry Forest is well represented, it is protected mostly as an ‘Integrated Management Natural Area’, and thus lacks full protection. The Semi-Humid Puna and the Flooded Savannas of the Moxos Plains, important subdivisions of two main ecoregions, are markedly under-represented in the NSPA, despite the importance of Moxos plains as a center of endemism for birds. Other ecoregions have a representation in the NSPA which can be considered adequate or even excessive. The over-representation of the humid Yungas mountain forests seems to be justified as this is probably Bolivia’s most important center of diversity and endemism. There is a need for a more proper distribution of some protected areas which consider true limits, size, diversity, endemism and other attributes of the different ecoregions in a more rigorous manner.     

Hotspots and ecoregions: a test of conservation priorities using taxonomic data

The loss of biodiversity is now recognized as a global problem of significant magnitude [ Science 289: 2279]. Conservation efforts focus on measuring species diversity and distribution, assessing biodiversity threats, and managing habitats to maintain that diversity. The accuracy of measuring species diversity depends on the quality and scale of the data. Recently indirect estimates of diversity based on the skilled opinions of international taxonomic authorities were used to define 25 global conservation hotspots [ Nature 403: 853–858] and 871 ecoregions [ Bioscience 51: 933–938]. These data, originating from first-hand fieldwork and museum study, are readily available, but not necessarily repeatable nor testable. If this type of information prevails for conservation purposes, it is critical that we test the quality of this information with verifiable data at finer scales (e.g., regional inventories, specimen records, and accumulated distribution data). Here we perform such a test for the hotspots and ecoregions found in the Indo-Pacific by comparing the estimates of the expert scientists with authenticated published diversity data on flowering plants. We found a high correlation between our counts of species richness and endemism with the experts' estimates, but surprisingly found less congruity among the seven families examined. A revised list of conservation priority regions based on our plant data is provided.     

Key Neotropical ecoregions for conservation of terrestrial vertebrates

Conservation planning analyses show a striking progression from endeavors targeted at single species or at individual sites, to the systematic assessment of entire taxa at large scales. These, in turn, inform wide-reaching conservation policies and financial investments. The latter are epitomized by global-scale prioritization frameworks, such as the Biodiversity Hotspots. We examine the entire Neotropical region to identify sets of areas of high conservation priority according to terrestrial vertebrate distribution patterns. We identified a set of 49 ecoregions in which 90, 82 and 83%, respectively of total, endemic and threatened vertebrates are represented. A core subset of 11 ecoregions captured 55, 27 and 38% of these groups. The Neotropics hold the largest remaining wilderness areas in the world, and encompass most of the tropical ecosystems still offering significant options for successful broad-scale conservation action. Our analysis helps to elucidate where conservation is likely to yield best returns at the ecoregion scale.     

A trait-based approach to assess climate change sensitivity of freshwater invertebrates across Swedish ecoregions

Freshwater habitats and organisms are among the most threatened on Earth, and freshwater ecosystems have been subject to large biodiversity losses. We developed a Climate Change Sensitivity （CCS） indicator based on trait information for a selection of stream- and lake-dwelling Ephemeroptera, Plecoptera and Trichoptera taxa. We calculated the CCS scores based on ten species traits identified as sensitive to global climate change. We then assessed climate change sensitivity between the six main ecoregions of Sweden as well as the three Swedish regions based on lilies. This was done using biological data from 1,382 stream and lake sites where we compared large-scale （ecoregional） patterns in climate change sensitivity with potential future exposure of these ecosystems to increased temperatures using ensemble-modelled future changes in air temperature. Current （1961-1990） measured temperature and ensemble-modelled future （2100） temperature showed an increase from the northernmost towards the southern ecoregions, whereas the predicted temperature change increased from south to north. The CCS indicator scores were highest in the two northernmost boreal ecoregions where we also can expect the largest global climate change-induced increase in temperature, indicating an unfortunate congruence of exposure and sensitivity to climate change. These results are of vital importance when planning and implementing management and conservation strategies in freshwater ecosystems, e.g., to mitigate increased temperatures using riparian buffer strips. We conclude that traits information on taxa specialization, e.g., in terms of feeding specialism or taxa having a preference for high altitudes as well as sensitivity to changes in temperature are important when assessing the risk from future global climate change to freshwater ecosystems [Current Zoology 60 （2）： 221-232, 2014].     

Integrative exposure assessment through classification and regression trees on bioaccumulation of metals, related sampling site characteristics and ecoregions

The UNECE Heavy Metals in Mosses Surveys measure and spatially predict environmental concentration (PEC) of metals in mosses for ecotoxicological risk assessments. Up to now, no statistical sound investigation was dedicated to those boundary conditions which, aside from the atmospheric depositions of metals from the atmosphere down to the land surface, might influence the bioaccumulation of metals. Thus, the article focuses on the integrative analysis of the data on the bioaccumulation of metals in Germany 1990, 1995 and 2000 on the one hand and of data on conceivable boundary conditions on the other hand. To this end Classification and Regression Trees (CART) were used because CART is a very powerful statistical technique that enables to uncover structures in large data sets containing categorical and continuous data without any transformation of scale dignity. Within the framework of the Metals in Mosses Surveys, moss samples were taken at 592 sites in 1990, at 1026 sites in 1995 and at 1028 sites in 2000 in Germany. At each of them mosses were sampled and the concentrations of up to 40 metals were measured. The sampling, the ecological characteristics of the sampling sites, and the chemical analysis were documented in a metadata base. An ecoregionalisation of Germany was calculated with data on natural vegetation, altitude, soil texture and climate by means of CART. The ecoregions were mapped by GIS and intersected with multi-metal bioaccumulation indices calculated from the monitoring data 1990, 1995 and 2000. These indices were calculated by percentile statistics and the concentrations of As, Cd, Cr, Cu, Fe, Hg, Ni, Pb, V and Zn were integrated. To reach an integrative exposure assessment, for each survey a CART-model was computed encompassing the multi-metal bioaccumulation indices, the metadata and the ecoregionalization. The models describe the multivariate correlations of metal bioaccumulation with site-specific and ecoregional characteristics in a comprehensive and holistic manner over time, space and metal species. This is of crucial importance for the next step in ecological risk assessment, i.e. the interpretation of the exposure data with regard to predicted no effect concentrations (PNEC) and the sensitivity of ecosystems.     

Patterns in the species composition of fish assemblages among Wisconsin streams

Synopsis To better understand patterns of fish assemblage composition in Wisconsin streams in relation to major environmental gradients, I carried out multivariate direct gradient analysis (canonical correspondence analysis) of two large independent datasets on fish species abundance in Wisconsin streams. Analysis of the two datasets yielded similar results, suggesting that observed patterns and relationships were real. Stream sites were distributed along fish species-environment gradients, but segregation into distinct stream temperature and geographic groups was also evident. The strongest gradient in both datasets was related to summer water temperature patterns, and encompassed a transition from small, coldwater streams dominated by salmonids, cottids, certain cyprinids, and few other species, to both small and large, warmwater streams dominated by a high diversity of different cyprinids, catostomids, ictalurids, centrarchids, and percids. A second gradient in both datasets was complex but largely geographic. Within it, sites from each of the four ecoregions that occupy Wisconsin formed fairly discrete groups. The strongest differences were between sites in the two southern Wisconsin ecoregions, the Driftless Area and the Southeastern Wisconsin Till Plains, that were dominated by certain cyprinids, ictalurids, and centrarchids, and sites in the two northern Wisconsin ecoregions, the North Central Hardwood Forests and the Northern Lakes and Forests, that were dominated by a different set of cyprinids and ictalurids, plus some petromyzontids, salmonids, catostomids, and percids. Sites from the Driftless Area that were mostly higher-gradient (steep stream slope) and had many riffle-dwelling species could also be distinguished from sites in the Southeastern Wisconsin Till Plains that were mostly lower-gradient and had many pool-dwelling species. The patterns of fish assemblage composition among sites and the associated fish species-environment relationships that were revealed by the analyses provided a framework for developing an ecologically meaningful hierarchical classification of Wisconsin stream sites based on stream thermal regime, ecoregion, stream size, and stream gradient.