Happily, recent collaborative syntheses have reduced these tensions and identified important new directions of investigation (e.g., Loreau et al. 2001; Hooper et al. 2005). Second, there are different measures of ecosystem function relevant to human well-being, including primary and secondary productivity, stability, resistance to invasion, and resilience, and there is little reason to expect that these different characteristics will be affected by biodiversity losses in similar ways (Hooper et al. 2005; Loreau et al. 2001; Schwartz et al. 2000). Third, multiple mechanisms may be responsible for observed relationships between diversity and ecosystem function (Loreau et al. 2002), highlighting one of the frequent difficul-ties ecologists face in attempting to infer processes from patterns. Finally, much of the recent experimental work has focused on studying the effects of manipulation of small-scale systems with relatively low species richness (e.g., McGrady-Steed et al. 1997; Petchey et al. 1999; Thébault and Loreau 2003; Tilman 1999). As most applied conservationists are primarily concerned with complex, large-scale systems, the practical relevance of insights gained from the study of much simpler systems is debatable on several grounds (e.g., Aarson 1997; Carpenter 1996; Hooper and Vitousek 1997; Huston 1999; Huston and McBride 2002; Rosenfeld 2002; Strivastava and Vellend 2005).
From a conservation standpoint, the key question is related to ecological redundancy (Lawton and Brown 1993; Rosenfeld 2002): are all species in an ecosystem necessary to sustain normal function, or can most ecosystem services be provided by a small subset of species (i.e., are many species functionally redundant)? It is unlikely that there is a universal relationship between diversity and ecosystem function across all ecosystem types and functions (Hooper et al. 2005; Naeem et al. 1994). Some studies indicate that there are relatively high degrees of ecological redundancy and that substantial losses in biodiversity may have limited effects on the provision of certain ecosystem services, especially at small temporal and spatial scales or when environmental variability is relatively low (Hooper et al. 2005; Loreau et al. 2001; Schwartz et al. 2000, but see Rosenfeld 2002). However it should be noted that these studies typically use a limited definition of ecosystem function (often restricted to the effects of biodiversity loss on plant biomass), and many restrict their analyses to examining the effects of biodiversity loss within one trophic level. At larger temporal and spatial scales and in changing environments the number of species required to maintain ecosystem services increases (Hooper et al. 2005; Loreau et al. 2001, 2002). Research has now largely shifted away from focusing on simple indices of species richness to attempting to identify key functional species or groups that have disproportionate effects on ecosystem services (Loreau et al. 2001; Naeem and Wright 2003; Rosenfeld 2002).
There is debate over the extent to which biodiversity-ecosystem function studies have direct relevance for conservation biology (Hector et al. 2001; Lawler et al. 2001; Schwartz et al. 2000; Srivastava and Vellend 2005). The lack of universal support for a direct link between biodiversity and ecosystem function has led some to suggest that widespread use of this linkage as a justification for conservation goals is unwise (Krebs 2001; Lawler et al. 2001; Schwartz et al. 2000). Others acknowledge this point but argue that interactions between biodiversity and ecosystem services can provide useful additional arguments in support of conservation (Hector et al. 2001). It has also been suggested that although research on the relationship between biodiversity and ecosystem function has had limited conservation applications to date, this area promises to provide important insights into conservation policy in the foreseeable future (Lawler et al. 2001; Srivastava and Vellend 2005). While there is much debate in academic circles on how reduction in species richness or loss of key functional groups will effect the function and stability of ecosystems (and the pertinence of these debates to more applied conservation issues), the vast majority of ecologists agree that these losses will increase susceptibility to invasion by exotic species (and presumably also pathogens), reduce environmental services, and negatively impact the biosphere (Hooper et al. 2005; Loreau et al. 2001; Schla¨pfer et al. 1999). Therefore, as ecologists work to identify which species and functional groups are irreplaceable, a precautionary approach to biodiversity preservation should serve as a broad governing theme in conservation management in Papua.
THE PAPUAN PROTECTED AREAS NETWORK
The Papuan protected areas network encompasses approximately 66,500 km2 of terrestrial habitats. The major ecosystems are not equally or proportionately represented within Papua’s protected area system (Table 5.1.3). The most well protected land cover classes are lower montane forests and subalpine forests, with over 45% of each ecosystem type found within formally protected areas. However, lowland evergreen forest, by far the most dominant ecosystem type in Papua (61% of land area), is proportionately the least well represented in protected areas, with only 14.5% of this ecosystem type occurring within currently designated parks and reserves. This is a source of major concern as lowland forest is the ecosystem type most likely to suffer heavy degradation from uncontrolled human development, logging, and mining. In other parts of Indonesia almost all lowland forest found outside protected areas has disappeared or been severely degraded (Fuller et al. 2004; Holmes 2002; Jepson et al. 2001; van Schaik et al. 2001; World Bank 2001), with substantial losses even occurring within protected areas (Curran et al. 2004). Although this trajectory of habitat loss is far from inevitable in Papua, we would be well advised to consider the worst-case scenario that few forests in Papua will exist in their present state outside protected areas at the end of the 21st century. Under this scenario the current protected areas network in Papua is unlikely to be sufficient to protect the full complement of species, ecological processes, and ecosystem functions that is found there today. Assessment of this possibility will require careful consideration of the representation of ecosystem types within the current Papuan protected areas network, the prospects for maintaining connectivity between ecosystems, and the potential effects of global and regional climate change on the spatial distribution of ecosystems.
Unforested lands are excluded. GIS analysis of protected areas map overlaying Landsat 7 ETM imagery of Papua, using a combination of images acquired in 1999 and 2000.
Source: Forest Watch Indonesia–Conservation International–Ministry of Forestry.
ECOSYSTEM-BASED CONSERVATION APPROACHES
Numerous strategies are currently employed and championed by scientists, conservation organizations, and government agencies involved in natural resource management. The widely-publicized ‘‘Biodiversity Hotspots’’ approach advocates prioritizing severely threatened areas of high species richness and endemism (Myers et al. 2000). Other strategies suggest that preservation of large wilderness areas that are ecologically intact and sparsely populated represent important opportunities for biodiversity conservation (Mittermeier et al. 2003). Some have argued that conservation efforts should focus almost exclusively on landscapes that are largely unaltered by humans (e.g., Myers 1980; Noss 1991), while others embrace the conservation potential of the careful management of lands that have already been substantially impacted (e.g., by development or logging, Fimbel 1994; Fimbel et al. 2001; Frumhoff 1995; Johns 1983; Marshall et al. 2006; Meijaard et al. 2005). Integrated conservation and development projects promise simultaneously to protect biodiversity and promote human well-being, health, and poverty alleviation (Goodwin and Swingland 1996; McShane and Wells 2004; Salafsky et al. 2001), while others suggest that the most effective way to conserve wildlife and habitats is strict protection and exclusion of most local people from protected areas (e.g., Terborgh 1999). Numerous campaigns have focused on the conservation of single species or specific taxonomic groups (e.g., Mittermeier et al. 2005; Stattersfield et al. 1998) and others work to preserve ecosystems, ecoregions, or functional landscapes (Hudson 1991; Noss 1996; Pressey et al. 1993; Woinarski et al. 1996). Each approach has strengths and limitations (Bonn and Gaston 2005; Kareiva and Marvier 2003; Kiss 2004; Young 1999; Orme et al. 2005; Possingham and Wilson 2005), and it is likely that the most favorable conservation outcomes will result from careful application of a broad portfolio of conservation tactics and strategies.
Although a range of conservation strategies have applicability to Papua, the fact that Papua’s ecosystems provide services of local, regional, and
