Showing papers by "Guy F. Midgley published in 2002"

Conservation of Biodiversity in a Changing Climate

Abstract: *Center for Applied Biodiversity Science, Conservation International, Washington, D.C, 20037, U.S.A.†Climate Change Research Group, Ecology and Conservation, National Botanical Institute, Cape Town, South Africa‡The World Bank, Washington, D.C. 20433, U.S.A.§Botany Department, University of Cape Town, Cape Town, South Africa**Department of Biological Sciences, College of Science and Liberal Arts, Florida Institute of Technology, Melbourne,FL 32901–6975, U.S.A.††Environment Department, University of York, York, Y010 5DD, United Kingdom‡‡Adaptation and Impacts Research Group, Environment Canada at the Faculty of Environmental Studies, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada§§Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, United Kingdom

Climate change‐integrated conservation strategies

Abstract: Aim Conservation strategies currently include little consideration of climate change. Insights about the biotic impacts of climate change from biogeography and palaeoecology, therefore, have the potential to provide significant improvements in the effectiveness of conservation planning. We suggest a collaboration involving biogeography, ecology and applied conservation. The resulting Climate Change-integrated Conservation Strategies (CCS) apply available tools to respond to the conservation challenges posed by climate change. Location The focus of this analysis is global, with special reference to high biodiversity areas vulnerable to climate change, particularly tropical montane settings. Methods Current tools from climatology, biogeography and ecology applicable to conservation planning in response to climate change are reviewed. Conservation challenges posed by climate change are summarized. CCS elements are elaborated that use available tools to respond to these challenges. Results Five elements of CCS are described: regional modelling; expanding protected areas; management of the matrix; regional coordination; and transfer of resources. Regional modelling uses regional climate models, biotic response models and sensitivity analysis to identify climate change impacts on biodiversity at a regional scale appropriate for conservation planning. Expansion of protected areas management and systems within the planning region are based on modelling results. Management of the matrix between protected areas provides continuity for processes and species range shifts outside of parks. Regional coordination of park and off-park efforts allows harmonization of conservation goals across provincial and national boundaries. Finally, implementation of these CCS elements in the most biodiverse regions of the world will require technical and financial transfer of resources on a global scale. Main conclusions Collaboration across disciplines is necessary to plan conservation responses to climate change adequately. Biogeography and ecology provide insights into the effects of climate change on biodiversity that have not yet been fully integrated into conservation biology and applied conservation management. CCS provide a framework in which biogeographers, ecologists and conservation managers can collaborate to address this need. These planning exercises take place on a regional level, driven by regional climate models as well as general circulation models (GCMs), to ensure that regional climate drivers such as land use change and mesoscale topography are adequately represented. Sensitivity analysis can help address the substantial uncertainty inherent in projecting future climates and biodiversity response.

Assessing the vulnerability of species richness to anthropogenic climate change in a biodiversity hotspot

Abstract: Aim To compare theoretical approaches towards estimating risks of plant species loss to anthropogenic climate change impacts in a biodiversity hotspot, and to develop a practical method to detect signs of climate change impacts on natural populations. Location The Fynbos biome of South Africa, within the Cape Floristic Kingdom. Methods Bioclimatic modelling was used to identify environmental limits for vegetation at both biome and species scale. For the biome as a whole, and for 330 species of the endemic family Proteaceae, tolerance limits were determined for five temperature and water availability-related parameters assumed critical for plant survival. Climate scenarios for 2050 generated by the general circulation models HadCM2 and CSM were interpolated for the region. Geographic Information Systems-based methods were used to map current and future modelled ranges of the biome and 330 selected species. In the biome-based approach, predictions of biome areal loss were overlayed with species richness data for the family Proteaceae to estimate extinction risk. In the species-based approach, predictions of range dislocation (no overlap between current range and future projected range) were used as an indicator of extinction risk. A method of identifying local populations imminently threatened by climate change-induced mortality is also described. Results A loss of Fynbos biome area of between 51% and 65% is projected by 2050 (depending on the climate scenario used), and roughly 10% of the endemic Proteaceae have ranges restricted to the area lost. Species range projections suggest that a third could suffer complete range dislocation by 2050, and only 5% could retain more than two thirds of their range. Projected changes to individual species ranges could be sufficient to detect climate change impacts within ten years. Main conclusions The biome-level approach appears to underestimate the risk of species diversity loss from climate change impacts in the Fynbos Biome because many narrow range endemics suffer range dislocation throughout the biome, and not only in areas identified as biome contractions. We suggest that targeted vulnerable species could be monitored both for early warning signs of climate change and as empirical tests of predictions.

Economic impacts of climate change in South Africa: a preliminary analysis of unmitigated damage costs

Abstract: What are the predicted economic impacts of climate change in South Africa? This paper attempts to provide preliminary estimates based on secondary data from the findings of the Vulnerability and Adaptation Study for the South African Country Study on Climate Change (1999). The impacts on natural, agricultural, human-made and human capital are addressed using the change in production approach..Findings include the following:Tourism may be affected due to a loss of habitats and biodiversity, and due to changes in temperature, humidity and malaria risk, and represents the biggest potential economic loss since tourism contributes as much as 10% of GDP.Changes in ecosystem function, the loss of biodiversity and non-market impacts, brought about by changes in temperature and precipitation, represent the second largest potential economic impact.Significant decrease in river flow in the southern and western catchments are predicted, leading to a shrinkage of areas amenable to the country’s biomes to about half of their current extent, with huge losses in biodiversity.The productivity of rangelands increases due to a CO2 fertilisation effect.Whilst changes in terrestrial animal diversity could not be predicted accurately, the study suggests huge losses of species due to range shifts.Forests, small but locally valuable in terms of commercial production of timber and non-timber products stand to be entirely lost.Savannas, important for grazing and the subsistence harvest of numerous resources may be radically reduced, leading to large losses of productive value.Agricultural systems are not nearly as affected as natural systems with the impacts on crop production relatively minor in relation to the value of the sector as a whole.Finally, the impacts of climate change on human health are considered, concentrating on the increased incidence of malaria, the proportion of deaths being expected to increase and the costs in terms of the treatment costs of the sick and the loss of earnings of the sick or their carers.

Hierarchical processes define spatial pattern of avian assemblages restricted and endemic to the arid Karoo, South Africa

Abstract: Aim To identify and quantify biotic and abiotic factors associated with the regional gradients in the distribution and abundance of bird communities restricted and endemic to the Succulent and Nama Karoo biomes of South Africa. Location The arid Nama and Succulent Karoo biomes in South Africa. Methods The quarter degree grid cell (QDGC) was used to extract environmental data, while the bird data previously atlased, was linked to the same geo-referenced system, using a geographical information system (GIS). Bird species were grouped into different life-history assemblages. A quantitative, systematic analysis of the different bird communities spanning the Karoo was undertaken to examine contributions of broad- and local-scale physical environmental and biotic factors to regional variations in the species composition, using multivariate statistical and spatial analytical tools. These included two indirect gradient methods; principal components analysis (PCA) and detrended correspondence analysis (DCA), and two direct gradient methods; canonical correspondence analysis (CCA) and redundancy analysis (RDA). Results Principal components analysis results showed that the selected environmental variables accounted for about 85% of the variation in the region. The first two principal gradients defined regional temperature seasonality and variability especially in winter and summer. The third principal gradient mainly defined summer rainfall areas in association with the coefficient of variation of rain and regional primary production, while the fourth gradient defined winter rainfall areas, growth days and elements of landscape structure. CCA ⁄ RDA analysis produced shortened hierarchically ranked explanatory variables for each bird assemblage. Stepwise gradient analysis results showed summer rain, rainfall concentration, topographic heterogeneity and annual evapotranspiration, as the most important climate variables explaining species occurrence. Landscape, in terms of percentage transformation, morphology, coefficient of variation of primary productivity and distance between suitable habitat patches, were also important, but to a lesser degree. Total variation explained (TVE) by the supplied variables was between 23 and 37% of variation. Less than 20% of TVE was the intrinsic spatial component of environmental influence, indicating that any unmeasured factors were independent of spatial structuring. For all the eight bird assemblages, climate contributed most to TVE (24‐57%). Landscape characteristics (human-induced transformation, vegetation in terms of size if grassy clumps and the average distances between them) contributed the least to TVE for all the different assemblages (0‐6%), especially the granivorous assemblage where it was not significant at all (0%). Seasonal extremes and variability were more important in explaining species gradients than were annual climatic conditions, with the exception of annual potential evapotranspiration.

Why were dinosaurs so large? A food quality hypothesis

Abstract: Some dinosaurs, notably the sauropods, were the largest of all land animals, present or past. There is no generally agreed reason for this gigantism. We question the recent suggestion that this was due to high productivity, from high COP 2 concentrations, at the time of the dinosaurs. Instead, we suggest the reason for this large size was because typical Jurassic/Triassic plants, such as cycads and conifers, were of inherently low food quality (low nitrogen concentration). High CO 2 at the time of the dinosaurs would have resulted in an even lower food quality. Present-day megaherbivores are associated with relatively low-quality food-plants and we suggest this applied to sauropods.

Response to elevated CO2 from a natural spring in a C4-dominated grassland depends on seasonal phenology

Abstract: A South African C4-dominated grassland was exposed to twice-ambient atmospheric CO2 concentration using gas emitted by a natural CO2 spring and distributed over a 7m x 7m plot. A similar control plot was established 20m away at near-ambient CO2 concentrations. Photosynthetic CO2 response curves were performed on three C4 and one C3 grass species under both treatments, in spring (post-fire), mid-summer and autumn. Photosynthetic efficiency of the post-fire dominants, Alloteropsis semialata subsp. eckloniana (C3) and Andropogon appendiculatus (C4) was significantly enhanced in high CO2 only during the early season, when photosynthetic capacity was high. Thereafter, photosynthetic capacity decreased with advancing season in both species, and positive responses to high CO2 were lost or reduced. In the mid- to late-season dominant Themeda triandra (C4), photosynthetic capacity was maintained in elevated CO2 during the mid- to late-season, while decreasing in ambient CO2 relative to high CO2. Eragrostis racemos...