Endemic species and ecosystem sensitivity to climate change in Namibia

Abstract

We present a first assessment of the potential impacts of anthropogenic climate change on the endemic flora of Namibia, and on its vegetation structure and function, for a projected climate in similar to 2050 and similar to 2080. We used both niche-based models (NBM) to evaluate the sensitivity of 159 endemic species to climate change (of an original 1020 plant species modeled) and a dynamic global vegetation model (DGVM) to assess the impacts of climate change on vegetation structure and ecosystem functioning. Endemic species modeled by NBM are moderately sensitive to projected climate change. Fewer than 5% are predicted to experience complete range loss by 2080, although more than 47% of the species are expected to be vulnerable (range reduction > 30%) by 2080 if they are assumed unable to migrate. Disaggregation of results by life-form showed distinct patterns. Endemic species of perennial herb, geophyte and tree life-formsare predicted to be negatively impacted in Namibia, whereas annual herb and succulent endemic species remain relatively stable by 2050 and 2080. Endemic annual herb species are even predicted to extend their range north-eastward into the tree and shrub savanna with migration, and tolerance of novel substrates. The current protected area network is predicted to meet its mandate by protecting most of the current endemicity in Namibia into the future. Vegetation simulated by DGVM is projected to experience a reduction in cover, net primary productivity and leaf area index throughout much of the country by 2050, with important implications for the faunal component of Namibia's ecosystems, and the agricultural sector. The plant functional type (PFT) composition of the major biomes may be substantially affected by climate change and rising atmospheric CO2- currently widespread deciduous broad leaved trees and C-4 PFTs decline, with the C-4 PFT particularly negatively affected by rising atmospheric CO2 impacts by similar to 2080 and deciduous broad leaved trees more likely directly impacted by drying and warming. The C-3 PFT may increase in prominence in the northwestern quadrant of the country by similar to 2080 as CO2 concentrations increase. These results suggest that substantial changes in species diversity, vegetation structure and ecosystem functioning can be expected in Namibia with anticipated climate change, although endemic plant richness may persist in the topographically diverse central escarpment region

Potential, realised, future distribution and environmental suitability for Pterocarpus angolensis DC in southern Africa

“…Currently, the choice of predictors remains a challenge (Ashcroft et al, 2011) and it is remarkable that a lot of studies do not use an objective selection method (Acevedo et al, 2012;Elith and Leathwick, 2009;Elith et al, 2006;Phillips et al, 2006;Thuiller et al, 2006;Zimmermann et al, 2009) Early test runs of the models indicated that validation results also improved when both training and test points in Namibia and South Africa -that had a relative overrepresentation of occurrences and thus induced a bias in the data -were reduced. However, when only the training points were reduced, the model performed worse because of the bias in the test points.…”

Patterns of forest composition and their long term environmental drivers in the tropical dry forest transition zone of southern Africa

“…The impact of global change on Africa's dry forests is unclear as predicted climate changes vary at a regional scale while increasing CO 2 and drought can have opposite effects on tree cover (Hély et al 2006;Lucht et al 2006;Thuiller et al 2006;Leadley 2010;. Transition zones from open dry forest to shrub and grassland can expect the largest impact, particularly where mean annual rainfall has a pronounced effect on woody cover (Sankaran et al 2005(Sankaran et al , 2008 (Fig.…”

Are Swiss birds tracking climate change?

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