Several small fragments can have higher species richness than a single large: the SLOSS debate in agricultural landscapes

Abstract

Whether a Single Large (SL) is better than Several Small (SS) areas of natural vegetation (SLOSS) to maintain biodiversity in human-altered landscapes is still contentious. Here, we argue that the SLOSS debate has no single solution, because SS may have higher species richness (γ-diversity) than a SL and that it is critical for biodiversity conservation. We used multitaxa data from different years sampled in an experimental area designed to test SLOSS predictions and dominated by intensive farming. We compared whether a SL patch of natural vegetation has higher species richness than the sum of SS patches with total area equal to the SL. We found that for most taxa SS had higher γ-gamma diversity than a SL. Furthermore, beta diversity among SS was not correlated with spatial distance among them for most taxa. Our findings underscore that the contribution of SL or SS to maintain species richness cannot be generalized. Therefore, the importance of SS for maintaining biodiversity in agricultural landscapes, which intrinsically can support different mechanisms and interactions compared to landscapes with lower anthropic influence, need to be properly recognized, keeping the SS in a leading role as they are most of the natural vegetation areas remaining worldwide.