Climate Change, Connectivity, and Conservation Success

Ten years ago in the pages of Conservation Biology, Whitten et al. (2001) asked whether writing about conservation biology served as displacement behavior for biologists. Their point was that extensive destruction of forests in Southeast Asia coincided with a surge in publications about conservation in the region (Whitten et al. 2001). Were biologists writing papers because they had lost the real conservation battle? The same question applies today to climate change. Is studying climate-change biology a kind of displacement behavior for conservation professionals? Is our professional community writing so much about climate change because we have been impotent in addressing habitat loss, the real alpha male of modern conservation? It is a challenge to address future threats without allowing them to distract all attention from current action. Although each of us needs to reflect on our motivations and effectiveness, the scientific basis for action can be more objectively evaluated. Scientists have been exploring climate-change biology for approximately the same amount of time that Conservation Biology has been published. The seminal papers of Peters and others (e.g., Peters Mawdsley et al. 2009). These elements can now be implemented and the experience from that action used to refine theory and practice, iteratively improving our practical abilities. Establishment of protected areas, a leading conservation tool before climate change gained attention, is also an effective measure in response to climate change (Hannah et al. 2007). The placement of new protected areas can anticipate climate change, substantially improving the probability that species and ecosystem functions will be maintained in reserves. Where protected areas are too small to encompass species and ecosystem functions, connectivity between present and future populations is required. Populations, rather than protected areas, are the key elements to be connected, as is explored below. Where natural processes are more extensive than individual protected areas, adaptive management can facilitate range shifts (Hansen et al. 2003). Coordination across management units is critical. Species may need to be relocated to persist given the very rapid pace of human-induced climate change (McLachlan et al. 2007). For instance, where agricultural or urban land or a topographic barrier interrupts a range shift, artificial movement of the species or its propagules may be warranted (Hoegh-Guldberg et al. 2008). When all else fails, ex situ measures, including captive breeding and gene banking, may be necessary to preserve species and their genetic information. Gene and seed banks that expressly consider climate change are already being established. Protected areas and connectivity are the most important of these elements to implement because these responses have the potential to conserve the greatest number of species and ecosystems. By the time a species or ecosystem needs managed relocation or ex situ management, the potential for other types of action to conserve them is very limited. Connectivity is perhaps the most misunderstood of these essential tools. Connectivity is one of the most difficult concepts to apply to current practice because confusion exists in the literature about what needs to be connected. Multiple concepts of connectivity are used, often without definition. Connectivity for different purposes and at different scales is sometimes confounded. Concepts of connectivity as a response to climate change began to emerge with the first publications on climate change and biological diversity. Peters and Darling (1985) and Peters and Lovejoy (1992) recognized that species ranges shift in response to climate, whereas protected areas are fixed in space. Species ranges as characterized in these early concepts were monolithic (i.e., large, continuous areas in which the species was present everywhere and beyond which it was absent). These were representations of the extent of occurrence, the rough equivalent of a species’ range map in a field guide. To communicate the point that species ranges would shift as human-driven climate change accelerates these representations were sufficient. But when a conservation strategy needs to be developed, a much more nuanced view is needed, that of area of occupancy (habitat patches occupied by individual populations within the extent of occurrence). These are the populations that will be established or extirpated for climate change and that will collectively determine whether the species persists or becomes extinct. The early concepts of range shifts seemed consistent with emphasizing connectivity among protected areas. A species was either inside or outside a protected area, and if it moved out it would need to be protected at all steps along its travels until it was again in a protected site. A linear corridor between two protected areas seemed a logical mechanism for capturing this dynamic. A more nuanced view emphasizes populations. Most species exist in multiple populations within a protected area, as well as outside. As climate changes, some of these populations may increase in size while others decrease, and each population will represent a larger or smaller proportion of the total abundance of the species. Populations have a probability of extirpation and also a probability of colonization or recolonization as a function of the ability of propagules or individuals to move (Davis they are realms of action that must be tested and refined in the real world. There must be rapid movement along this learning curve so that responses precede the undesirable effects of climate change. Equally urgent is the need to recognize the speed at which thresholds are approaching. In Europe and the United States, loss of natural habitats has slowed and in some cases is reversing. In much of the tropics, habitat loss continues unabated. Madagascar is an extreme example, but not, unfortunately, the only one. Clearly, climate change needs to be understood at the same time habitat losses need to be halted or reversed. Yet a search of the recent peer-reviewed literature reveals that over the past year, over 2600 articles have appeared that address climate change and conservation strategies, while less than 50 have addressed whether funding for global conservation efforts is adequate or the targets of the Convention on Biological Diversity have been reached. Climate change is more complex than habitat loss. Adequate funding and achievement of Convention on Biological Diversity targets are relatively straightforward, but fundamentally important to what conservation professionals do and how successful we are in the near term. So, we may be justified in studying and writing about climate change. Responses to climate change will determine whether long-term conservation is successful. But if we do not also write about and secure the resources to avoid the land-use change threshold, we will ultimately be writing to ourselves, grooming each other, while the alpha males have dominion in Madagascar, Southeast Asia, and elsewhere.