Résumé

The phrase “Small is Beautiful” was first used by the talented scholar Leopold Kohr (1909–1994), but it became more popular thanks to the essays of one of his students, the British economist E. F. Schumacher, and it was coined as a response to the socially established idea that “Big is Powerful”. It could be argued that this desire for “bigness” explains why current legal frameworks and the conservation planning and management related to standing waters often overlook ponds, despite their well-known value in terms of biodiversity and socio-economic benefits (Oertli et al., 2004; Céreghino et al., 2008). Of course, this is only one of several possible explanations, but it is important to understand that such long-established ideas can have a lasting effect upon the efficiency of our conservation actions. Beyond this social perspective, the history of science can also provide some explanation as to why ponds have been undervalued for so long. Some of the first limnological work was undertaken during the late nineteenth–early twentieth century by the Swiss scientist François-Alphonse Forel on the ecology of Lake Geneva (1892, 1895, 1904). From this, one of the firsts treatises of limnology—“Die Binnengewässer Mitteleuropas” (Thieneman, 1925)—included a chapter on standing waters that included lakes, ponds, pools and bogs, but most of the chapter focussed upon the larger bodies of water—a trend replicated in the limnology books which followed (e.g. Arévalo, 1929; Naumann, 1932; Ruttner, 1940; Dussart, 1966; Wetzel, 1975; Margalef, 1983). Lakes, therefore, were the “cradle” of limnological studies. During the second half of the twentieth century, the study of limnology broadened to include the ecological processes in rivers and streams, thanks mainly to the H. B. N. Hynes’ masterful revision of the subject (Hynes, 1970). Ponds, however, remained overlooked and received significantly less scientific attention than streams, rivers and lakes. This is more surprising when several studies have established that (1) on a global scale they cover a greater total area than lakes (Downing et al., 2006); (2) their typical characteristics, such as shallow waters and small size, imply a different ecological functioning (Oertli et al., 2002; Søndergaard et al., 2005); (3) they play a major role in global cycles (Downing, 2010) and (4) they have high aquatic biodiversity (Wood et al., 2003; Williams et al., 2004). Despite the evidence that ponds per se receive less scientific attention than other water bodies (Oertli et al., 2009), in the scientific literature “ponds” are often included under other terms such as “shallow lakes” (e.g. Scheffer et al., 1993; Moss et al., 2009) or “wetlands” (e.g. Gopal et al., 2000; van der Valk, 2006), as in the USA where the term “wetlands” is often used to describe “ponds” (Batzer & Wissinger, 1996 and references therein; Batzer et al., 1999). These more general definitions may significantly reduce the level of scientific interest and could go some way to explain some of the biases that are regularly observed today in Europe’s Water Framework Directive (WFD) (Miracle et al., 2010). Ponds are too small to fit the standard model of site-based protection and they do not fit the standard model of consent-based protection applicable to lakes and running waters under Europe’s most powerful piece of water legislation. In this context, three emerging ideas have to be taken into account in pond management decisions: (1) the importance of pond networks in addition to isolated ponds (Gibbs, 2000; Jeffries, 2005); (2) to consider lesser known floral and faunal groups which, nevertheless, contain high biodiversity (i.e. diatoms, meiofauna and insects), and to use surrogate species with caution (i.e. having some idea of their effectiveness for the circumstances in which they will be applied; Favreau et al., 2006; Gascón et al., 2009; Bagella et al., 2011); and (3) differences in the community structure and ecological functioning of water bodies throughout Europe imply, for example, that some limnological paradigms used in the management of cold temperate ponds cannot be generalised to the Mediterranean region (Álvarez-Cobelas et al., 2005; Brucet et al., 2009, 2010).

Einzelheiten

Aktionen

PDF