The effects of organic agriculture on biodiversity and abundance: a meta-analysis
Originally published in 2005 in the Journal of Applied Ecology.
Organic agricultural methods are believed to be more environmentally sound than intensive agriculture, which is dependent on the routine use of herbicides, pesticides and inorganic nutrient applications in the production of crops and animals. Recent research suggests that organic agriculture results in less leaching of nutrients and higher carbon storage (Drinkwater et al. 1995), less erosion (Reganold, Elliott & Unger 1987) and lower levels of pesticides in water systems (Kreuger, Peterson & Lundgren 1999; Mäder et al. 2002), but some of these results have been questioned (Trewawas 1999; Goklany 2002).
Organic farming is reported to increase diversity in the agricultural landscape, including, for example, carabid beetles (Dritschilo & Wanner 1980; Kromp 1989; Pfinner & Niggli 1996), vascular plants (Hyvönen & Salonen 2002) and birds (Freemark & Kirk 2001). Based on such studies, it has been argued that organic agricultural methods generally increase biodiversity (Paoletti et al. 1992; Schönning & RichardsdotterDirke 1996; Ahnström 2002). This is particularly relevant because modern agriculture has resulted in a loss of diversity in the agricultural landscape (Fuller et al. 1995; Krebs et al. 1999; Stoate et al. 2001; Benton et al. 2002; Benton, Vickery & Wilson 2003), and it has been suggested that large-scale conversion to organic farming could partly ameliorate this loss. In the present study we used meta-analysis to evaluate the proposition that organic agricultural methods generally enhance biodiversity, operationally defined as species richness in a variety of organism groups.