Reality check: issues of scale and abstraction in biodiversity research, and potential solutions
Tasman P. Crowe, Matthew E. S. Bracken, and Nessa E. O'Connor
Over the past few decades, there has been extensive research into the relationship between biodiversity and the functioning of ecosystems—BEF research. Much of it has been done in terrestrial systems, and many of the seminal papers were terrestrially focused (e.g. Walker, 1992; Naeem et al. 1994; Tilman et al. 1996; Hector et al. 1999). This dominance and the tendency for terrestrial ecologists to ignore aquatic literature have both been documented (e.g. Raffaelli et al. 2005; Menge et al. 2009). However, BEF research in marine systems has proliferated in recent years (Stachowicz et al. 2007). There is a clear need to bridge the gap between terrestrial and marine ecologists, and to foster greater exchange of concepts, approaches and technology (Menge et al. 2009). Marine systems have a number of advantages for BEF research and are now yielding some influential findings (e.g. Stachowicz et al. 1999; Duffy et al. 2003; Solan et al. 2004; Bracken et al. 2008). Based on evidence to date, there appear to be some differences between BEF relationships in marine and terrestrial systems (Stachowicz et al. 2007 ). However, these comparisons may be hampered by differences in the approaches taken to terrestrial and marine BEF research (Stachowicz et al. 2008a ). Recent re-analyses of two large meta-datasets of BEF studies did not identify an overall tendency for biodiversity effects to vary among ecosystems, and the findings suggested that similar mechanistic processes may underpin BEF relationships in terrestrial and aquatic systems (Schmid et al. 2009).
It is important to recognize that BEF research can be primarily motivated by different overall objectives: (a) pure ecological research, to understand something about how the natural world works, and (b) to generate results applicable to real-world management problems. Of course this distinction is not by any means exclusive, but it can influence decisions about approaches to research because each of these objectives has different requirements and constraints. Much of the research undertaken to date has been justified by the need to understand the consequences of changing biodiversity because of potential links between biodiversity loss, and the loss of ecosystem goods and services provided by organisms in intact ecosystems. However, much of it is more correctly classified as pure ecological research, based on abstracted systems (Duffy 2009). Particularly in marine systems, the majority of published studies have been undertaken in laboratory mesocosms (Figure 13.1), which potentially limits their applicability to real-world biodiversity declines. In pure ecological terms, a considerable degree of progress has been made, and some widely accepted generalities are emerging (Hooper et al. 2005 ; Stachowicz et al. 2007). However, the extent to which these findings can be applied to specific management or conservation issues is less clear (Srivastava and Vellend 2005).
)n this chapter, we examine the nature of BEF research to date in marine systems, and specifically contrast it with that done in terrestrial systems. We then discuss limitations of our current knowledge, attributable in part to the approaches taken, before
Marine Biodiversity and Ecosystem Functioning. First Edition. Edited by Martin Solan, Rebecca J. Aspden, and David M. Paterson. © Oxford University Press 2012. Published 2012 by Oxford University Press.
Figure 13.1 Experimental arenas of all marine BEF studies, including those evaluating both consumer and primary producer diversity. Data are based on papers summarized in Stachowicz ef al. (2007). Relatively few studies (32%) have been conducted in the field; most (68%) have been done in the lab or in mesocosms. Parenthetical numbers over bars indicate the number of studies.
considering the relative merits of different approaches towards different objectives and making some suggestions for future research.