Figure 5.1.4. Schematic diagram of species richness and ecosystem diversity. The graph shows species-area curves for two landscapes. Landscape 1 (solid line) is comprised of a single ecosystem type (A). As more area is sampled the total number of species recorded increases, but slope decreases as an increasing proportion of the total species richness of ecosystem A is recorded. Landscape 2 (dashed line) is comprised of three ecosystem types (A, B, C). The species-area curves for the two landscapes are equivalent as long as sampling is confined to ecosystem A. However, as sampling begins in ecosystem B the species-area curve in Landscape 2 increases sharply as many new species are recorded in this new ecosystem type. Sampling of ecosystem C results in another rapid increase in total species richness in Landscape 2. This schematic shows that for any sampling area (e.g., a') species richness is higher in landscapes containing multiple ecosystem types than in landscapes comprised of a single ecosystem type (e.g., s ₂ > s ₁).

      INTERACTIONS AMONG ECOSYSTEM TYPES

      As is the case in many subjects within ecology and conservation biology, the more we learn about ecosystems the more we realize how connected and interdependent they are. As noted above, classification of ecosystems into discrete ‘‘types’’ masks the fact that there are many important interactions among them. For example, seagrass ecosystems provide an important functional link and buffer between reefs and mangrove ecosystems (Chapters 5.3 and 5.4) and forest ecosystems provide key nutrient inputs into aquatic and cave ecosystems (Chapters 5.5 and 5.13). This interdependence means that when one ecosystem is damaged it can have strong and often unforeseen effects on adjacent ecosystems. For example, uncontrolled clear-cutting of forest not only negatively effects forest ecosystems; the resultant erosion can also lead to detrimental siltation of downstream aquatic ecosystems (Chapter 5.5) and sediment deposition that can cause major harm to coral reefs (Chapter 5.2). Similarly, the smoke resulting from large-scale burning of lowland forests and peat swamps can have effects on other ecosystem types. For instance, the fires that occurred in Sumatra and Kalimantan in 1997 led to red tide phytoplankton blooms that caused large-scale death of coral reefs in the Mentawai Islands (Abram et al. 2003, 2004) and Bali (van Woesik 2004). We are only beginning to understand the complexity of interactions among ecosystem types, but these examples warn us that degradation of one ecosystem can have broad cascading effects on other ecosystems.

      Papuan Conservation: An Ecosystem Perspective

      Conservationists address questions across a broad range of spatial scales. Each of these approaches can yield valuable insights and have important implications for the preservation of biodiversity. Here I briefly consider some of the issues relevant to conservation of entire ecosystems. I consider the services provided by Papua’s ecosystems, discuss research into the relationship between biodiversity and ecosystem function, assess the representation of different ecosystems in Papua’s protected areas network, and consider the implications of an ecosystem perspective on Papuan conservation issues.

      ECOSYSTEM SERVICES

      The earth’s ecosystems provide a wealth of services necessary for human health and well-being, many of which are taken for granted or severely undervalued. Such services include purification of air and drinking water, reduction in the severity of droughts and floods, generation and preservation of soils and soil fertility, pollination of crops, nutrient cycling, climate stabilization, carbon sequestration, control of infectious disease, and erosion protection (Daily 1997; Krebs 2001). The relatively new field of natural resource economics has helped to raise awareness of the immense financial value of ecosystem services (Balmford et al. 2002, 2003; Balm-ford and Whitten 2003; Costanza 1991; Costanza et al. 1997; James, Gaston, and Balmford 1999; Peet 1992; Chapter 6.5), but the true benefits and costs of ecosystem services and their loss are rarely incorporated into decisions about natural resource management, particularly in developing countries. The financial costs associated with loss of ecosystem services resulting from degradation are rarely (or never) fully offset by those perpetrating the degradation, and the social and health costs are frequently disproportionately paid by people in lower economic groups. For example, the health costs alone associated with the Indonesian forest fires in 1997 have been estimated at 145 million U.S. dollars, with the majority of morbidity and mortality falling upon the poorest people in the region (Barber and Schweithelm 2000). Similar fires burn almost yearly and those who profit financially from these ecological disasters are not held accountable.

      Papua’s ecosystems provide environmental services of immense local, regional, and global importance. For example, Papua’s forests maintain water quality and prevent soil erosion for numerous local communities. Regionally, Papua’s man-groves serve as important breeding grounds for endangered vertebrates and commercially important marine invertebrates, sequester pollutants and environmental contaminants, protect against coastal erosion, and can even serve as physical barriers protecting humans from tsunami (Alongi 2002; Danielsen et al. 2005). More broadly, Papua’s extensive forests and seagrass ecosystems serve as globally important sites of carbon sequestration that help to ameliorate global climate change. Therefore sound management and conservation of Papua’s ecosystems will ensure that the valuable environmental services they provide will enhance human health and well-being for future generations.

      DIVERSITY AND ECOSYSTEM FUNCTION

      Because ecosystems provide such a wide range of services crucial to human health, substantial theoretical, empirical, and experimental work has addressed the relationship between diversity (or, more specifically, species richness) and ecosystem function. Although the theoretical roots of this discussion go back decades (Mac-Arthur 1955; May 1972; Statzner and Moss 2004), the unprecedented extinction rates resulting from human degradation of natural ecosystems have made this issue one of considerable practical relevance in recent years (Cameron 2002; Kinzig 2001; Loreau et al. 2001, 2002; Naeem et al. 1994; Schwartz et al. 2000). Examination of this topic is complicated by several issues. First, until recently, unusually contentious academic debate over the role of biodiversity in ecosystem functioning has polarized discussion, hampered important syntheses, and created skepticism towards this important work among the general public (Mooney 2002; Naeem et al. 2002). 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