A multi-scale 'portait' of factors influencing soil macrofauna biodiversity in Amazonia.
Mathieu, Jerome1, Rossi, Jean Pierre2, Mora, Philippe3, Lavelle, Patrick1, Grimaldi, Michel1, Rouland, Corinne1, 1 IRD, Laboratory of tropical soil ecology (LEST), Bondy, France2 INRA, Bordeaux, France3 Univ. of Paris 12, Créteil, France
ABSTRACT- The effects of deforestation on soil macrofauna communities remain largely understudied in Amazonia. Yet, soil macrofauna plays a great role in ecosystem functioning, through their action on the soil physical and chemical properties. We identified major environmental factors that shape the biodiversity of soil macrofauna in a landscape of actual deforestation, in south-east Amazonia. Thanks to our multi-scale sampling design, we show that the factors influencing the soil macrofauna change according to the scale considered. At the landscape level, the land use type and the landscape structure of the neighbourhood play an important role (up to 82 percent of the variance of the species richness can be explained). The diversity of the vegetation has no influence at this scale. At the plot level, the soil type influences the soil macrofauna through differences in water regime. At the transect level, the soil humidity has no more influence, but the presence of herb tuft in pasture, or the diversity of the litter in woodlands do. Thus, our study brings several new results: first it shows that landscape structure can influence below-ground biota. This is new to the problematic concerning above ground - below ground relationships. Second, we studied the effects of a wide range of environmental factors on soil macrofauna, at various scales, which offers the first multi-scale 'portrait' of the factors influencing the soil macrofauna biodiversity. Third, these results show that relationships between above ground and belowground biodiversity are scale dependent. This suggests that the scale of observation should absolutely be mentioned when talking about above ground - below ground biodiversity relationships.
Key words: soil biodiversity, landscape, above ground - below ground relationships, multi-scale
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