Biodiversity and Ecosystem Functioning

Abstract

Functional diversity, i.e., the kind, range, and relative abundance of functional traits present in a given community, is one of the major factors influencing ecosystem functioning (Chapin et al. 2000b; Díaz and Cabido 2001; Loreau et al. 2001; Hooper et al. 2005). Through its effects on ecosystem functioning, plant functional diversity (hereafter FD) is both affected by and affects all the major global change drivers identified by the international scientific community (Fig. 7.1, path 1). Changes in climate, atmospheric composition, land-use and disturbance regime, and biotic exchanges (deliberate or accidental introduction of organisms to an ecosystem) all have non-random effects on FD, i.e., they select for or against species bearing certain traits. For example, the more drought- and/or frost-sensitive species are eliminated first under an increased frequency of climatic extreme events (Díaz et al. 1999). Slow-growing species are eliminated when ecosystems experience nitrogen loading (Thompson 1994). Non-resprouting species are strongly reduced by increased fire return intervals (Russell-Smith et al. 2002; Johnson and Cochrane 2003). At the same time, through its effect on ecosystem processes, FD influences climate, carbon exchange with the atmosphere, disturbance regime, and the susceptibility to, and consequences of biotic exchanges (Fig. 7.1, path 2). In this chapter we focus on the processes of mutual influence and feedbacks between global change drivers and FD, and discuss the empirical evidence supporting the effect of different components of FD.