The need to develop a coherent research approach for climate change vulnerability impact assessment and adaptation in high-biodiversity terrestrial ecosystems

INTRODUCTION

It is important to assess the vulnerability of a broad range of ecosystems and biomes to the effects of anthropogenic climate change to inform appropriate adaptation responses. A striking feature of the key scientific document summarizing the vulnerabilities, and observed changes and responses of biodiversity to anthropogenic climate change is its reliance on studies of mid-to-high latitude Northern Hemisphere species and ecosystems (Fischlin et al. 2007; Parry et al. 2007; Rosenzweig et al. 2007; 2008). Relatively few studies have sought to identify actual- or projected-climate change impacts on globally recognized centres of species richness and endemism, most of which are located in the low-to-mid latitudes (Myers et al. 2000). This gap in knowledge may reflect an historical lack of investment in observation networks in these regions relative to the well-developed networks of the Northern Hemisphere.

It is yet to be established whether knowledge from regions in the Northern Hemisphere can be transferred globally. There may be aspects of high-biodiversity systems at low-to-mid latitudes that challenge the implementation of monitoring and modelling approaches which are considered appropriate for Northern Hemisphere higher-latitude ecosystems. We argue that there is a need to develop coherent science-based strategies for assessing vulnerability and measuring impacts and adapting to unavoidable climate change in high-biodiversity regions. Of particular concern are the global biodiversity hot spots in South-west Western Australia (SWWA) and the Cape in South Africa (Cape) both of which are predicted to become warmer and drier, and which are already under stress from a broad range of threatening processes (Myers et al. 2000; Christensen et al. 2007; CSIRO 2007; Bates et al. 2008). Relative climate stability during the Quaternary glacial/interglacial cycles probably explains at least partly the high levels of plant diversity in both regions and it is possible that anthropogenic climate change will exceed the climate range and rate of change that has buffered these systems against catastrophic extinction for millions of years (Jansson 2003; Hopper & Gioia 2004; Cowling et al. 2009; Verboom et al. 2009).

COMPARING AND CONTRASTING TWO STRONGLY RELATED HIGH-BIODIVERSITY REGIONS

Undertaking comparative research in two strongly related regions can yield important insights that might not be gained if activities were restricted to one region alone. South-west Western Australia and the Cape share many characteristics which make them ideal for such studies (for examples see Cowling et al. 1994; Cowling et al. 2005; Hopper et al. 2009). The two regions share a Gondwanan evolutionary heritage, similar Mediterranean climates, old and highly weathered nutrient poor soils with significant variation over short distances, and landscapes which experience recurrent fire (Hopper 2009). Similar ecosystems have evolved in both regions and many plant species share a number of convergent ecological traits (Cowling et al. 1994; Bond & van Wilgen 1996; Hopper & Gioia 2004; Cowling et al. 2005; Lambers et al. 2008; Hopper 2009). Patterns of plant diversity are characterized by moderate to high levels of local diversity within habitats and in adjacent habitats, but noteworthy are the exceptional levels of species turnover across the landscape (Cowling et al. 1994; Hopper & Gioia 2004; Rebelo et al. 2006). The floras in both regions are characterized by a mixture of ancient persistent and more recently radiated lineages indicating a potentially diverse set of responses to previous climate change (Hopper et al. 2009; Verboom et al. 2009). These characteristics pose many challenges for predicting and measuring the impacts of climate change and framing adaptation responses.

Also of value is the fact that there are striking differences between the two regions. Most notably, SWWA is topographically subdued with few opportunities for contraction into montane refuges, while the Cape is mountainous with some flat coastal plains. In addition, the Leeuwen Current brings warm tropical waters pole-ward to the coast of SWWA, while the Benguela upwelling system brings cold polar waters to the west coast of southern Africa creating localized climate effects. These differences enhance the utility of each region as a mutual control for the other.

Scientists in SWWA and the Cape have initiated a collaboration which aims to build the climate change and biodiversity science capacity in both regions. The initial outputs of the collaboration are three theme papers which follow in this volume (Abbott & Le Maitre 2009; Gioia 2009; Yates et al. 2009). The three papers review biodiversity modelling, monitoring and data management activities that will be critical for predicting and measuring climate change impacts and informing adaptation responses.

Species distribution models are one of the few spatially explicit tools available for predicting the impacts of climate change on biodiversity and are widely utilized. They are able to use data which are increasingly becoming available online through museum and herbarium collections and atlas projects. They have been widely used in the Cape and to a more limited extent in SWWA (e.g. Midgley et al. 2003; Fitzpatrick et al. 2008). Yates et al. (2009) review the utility of species distribution models in SWWA and the Cape in light of their many assumptions and the factors which have shaped species distributions in the two regions.

The predictions of species distribution models are seldom validated but where modelling and monitoring of population and range dynamics have been coupled, useful insights into model assumptions and the actual behaviour of systems have been gained (e.g. Foden et al. 2007). Abbott & Le Maitre (2009) discuss the critical role of monitoring in detecting the impacts of climate change on biodiversity, validating model predictions and in measuring the success of adaptive responses. They review the utility of different monitoring approaches in high-biodiversity systems such as SWWA and the Cape.

The effects of climate change on biodiversity and the success of adaptive management actions will take place over decadal scales. Monitoring biodiversity responses and associated environmental factors, including climate, will generate data that will need be stored and managed on a consistent and long-term basis, and in such a way that will serve analytical and evaluation applications. Gioia (2009) discusses the critical role of information management in science planning for climate change.