Spatial characteristics between biodiversity and ecosystem services in a human-dominated watershed

Abstract

Biodiversity and ecosystem services are intrinsically linked. Since human activities have both intensive and extensive impacts on the environment, it is critical to understand spatial relationships between conservation priorities for biodiversity and ecosystem services. The manner in which various aspects of biodiversity relate to ecosystem services and the spatial congruence between biodiversity and these services, is, however, unclear. In the present study in the Baiyangdian watershed, China, we investigated spatial characteristics of biodiversity and ecosystem services using correlation, overlap, and principal component, analyses. The spatial correlations between biodiversity and ecosystem services were found to be high. Biodiversity was positively correlated with soil retention, water yield and carbon sequestration and negatively correlated with N/P retention and pollination. Pairwise overlap was found to be the highest between N and P retention, biodiversity and carbon sequestration, and biodiversity and water yield. Other couples indicated moderate or small overlap. Principal component analysis indicated that biodiversity and six ecosystem services could be divided into two groups, which could be managed and conserved separately. It can be concluded that biodiversity priorities co-occur with water yield, soil retention and carbon sequestration, and do not co-occur with N/P retention and pollination. Conservation of a biodiversity hotspot was associated with maintaining 45.02% of a carbon sequestration hotspot, 42.05% of a water yield hotspot, and 23.29% of a soil retention hotspot, indicating that conserving biodiversity will also result in the protection of these services. The bundling of biodiversity and ecosystem services is thus both possible and practical. Our findings provide valuable information on congruence and divergence among conservation hotspots and the protection of ecosystem services. They also indicate that a systematic and comprehensive approach that can have wide-ranging policy implications in terms of optimizing conservation strategies for multiple ecosystem services.

Introduction

Biodiversity and ecosystem services – i.e. the benefits that humans derive from ecosystems – are intrinsically linked: the former underpins most ecosystem services and the maintenance of ecosystem services is often used to justify biodiversity conservation actions, because of the importance of such services in sustaining human livelihoods (Bookbinder et al., 1998, MA, 2005, Naughton-Treves et al., 2005, Egoh et al., 2009). Nevertheless, both biodiversity and ecosystem services are increasingly threatened by human activities (MA, 2005). The hope among conservation biologists and policy-makers alike is that existing and future conservation strategies can deliver on both biodiversity, and ecosystem services (Janzen, 1998, Balvanera et al., 2001, Daily and Matson, 2008, Goldman et al., 2008, Eigenbrod et al., 2009, de Groot et al., 2010). To achieve this, it becomes necessary to explore the links between biodiversity and ecosystem services (Burkhard et al., 2010).

The relationship between biodiversity and ecosystem services has not been a central concern of ecologists and has not, therefore, been of direct relevance to public policy. Recent studies have identified various important relationships: increases in biodiversity positively affecting productivity but decreasing stability (Pfisterer and Schmid, 2002); and the observation that conservation of biodiversity also results in the provision of additional ecosystem services (e.g. Ricketts et al., 2004, Russ et al., 2004). An IUCN report on post-2010 targets (IUCN, 2009) suggested that new targets could focus on human benefits of biodiversity arising through ecosystem services, which reflect the view that protecting ecosystem services also helps to protect biodiversity. Contrary to these initiatives, Egoh et al. (2009) concluded that the match between biodiversity and ecosystem services is not strong. Naidoo et al. (2006) argues further that by ignoring the cost side of conservation planning, ecologists and conservation biologists are missing great opportunities to more efficiently achieve conservation objectives in a world of limited conservation resources. The debate continues.

A more comprehensive understanding of the relationships between biodiversity and ecosystem services and the effectiveness of biodiversity conservation strategies in providing both biodiversity and ecosystem services is thus currently an important ecological issue (Odling-Smee, 2005, Sutherland et al., 2006, Eigenbrod et al., 2009).

The links between biodiversity and ecosystem services are complex (Costanza et al., 2007). Despite extensive discussion on relationships between biodiversity and ecosystem services, details on the ways in which various aspects of biodiversity relate to ecosystem services, and to what extent the conservation of biodiversity will ensure the provision of these services, remain unclear (Egoh et al., 2009, Pert et al., 2010). At present, much conservation effort is geared towards biodiversity per se and our knowledge of conserving ecosystem services is still in its infancy (Balvanera et al., 2001, Egoh et al., 2007).

Some studies have, however, evaluated spatial relationships between biodiversity and ecosystem services. Chan et al. (2006) found a poor relationship between biodiversity and ecosystem services, a generally low correlation between biodiversity and ecosystem services, and a moderate overlap between the two. In another study, Turner et al. (2007) found a generally high overlap between biodiversity priorities and ecosystem services. The ambiguity of these findings suggests that there is a need to extend the investigation into new regions that have not been extensively researched (Egoh et al., 2009).

In an increasing number of regions, the human population is so dense that extensive wilderness areas are entirely lacking. Anthropogenic drivers and their impacts on the relationships between biodiversity and ecosystem services of human-dominated landscapes are thus not well understood. The need to protect biodiversity and ecosystem services within human-dominated landscapes has been recognized by practitioners (Eigenbrod et al., 2009). Given the limited time, available resources, and looming imminent threats, to both biodiversity and to ecosystem services, we emphasize the need to prioritize this process by including human-related factors. In this study we assess the spatial congruence between biodiversity and ecosystem services in the Baiyangdian watershed, China, which is a human-dominated landscape. Specifically, we assess the opportunities for bundling biodiversity conservation with ecosystem services at the watershed scale and identify areas where protection of multiple benefits would be the most efficient. The broad aim of our paper is to present a systematic methodology for protecting biodiversity and ecosystem services in the world's watersheds.

We do this by asking the following questions:

• How much of each service is being generated by each land parcel?

• To what extent does biodiversity correlate with, or overlap with, other ecosystem services?