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Scale‐dependent species–area and species–isolation relationships: a review and a test study from a fragmented semi‐arid agro‐ecosystem
Author(s) -
Giladi Itamar,
May Felix,
Ristow Michael,
Jeltsch Florian,
Ziv Yaron
Publication year - 2014
Publication title -
journal of biogeography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 158
eISSN - 1365-2699
pISSN - 0305-0270
DOI - 10.1111/jbi.12299
Subject(s) - arid , species richness , ecosystem , biological dispersal , ecology , sampling (signal processing) , geography , biology , population , demography , sociology , filter (signal processing) , computer science , computer vision
Aim Patterns that relate species richness with fragment area (the species–area relationship, SAR ) and with isolation (the species–isolation relationship, SIR ) are well documented. However, those that relate species density – the number of species within a standardized area – with fragment area (D‐ SAR ) or isolation (D‐ SIR ) have not been sufficiently explored, despite the potential for such an analysis to disentangle the underlying mechanisms of SAR s and SIR s. Previous spatial theory predicts that a significant D‐ SAR or D‐ SIR is unlikely to emerge in taxa with high dispersal limitation, such as plants. Furthermore, a recent model predicts that the detection and the significance of D‐ SAR s or D‐ SIR s may decrease with grain size. We combined a literature review with grain size‐dependent sampling in a fragmented landscape to evaluate the prevalence and grain size‐dependent nature of D‐ SAR s and D‐ SIR s in plants. Location Worldwide (review) and a semi‐arid agro‐ecosystem in Israel (case study). Methods We combined an extensive literature review of 31 D‐ SAR studies of plants in fragmented landscapes with an empirical study in which we analysed grain size‐dependent D‐ SAR s and D‐ SIR s using a grain size‐dependent hierarchical sampling of species density and species richness in a fragmented, semi‐arid agro‐ecosystem. Results We found that significantly increasing D‐ SAR s are rare in plant studies. Furthermore, we found that the detection of a significant D‐ SAR is often possible only after the data have been stratified by species, habitat or landscape characteristics. The results from our case study indicated that the significance and the slopes of both D‐ SAR s and D‐ SIR s increase as grain size decreases. Main conclusions These results call for a careful consideration of scale while analysing and interpreting the responses of species richness and species density to fragmentation. Our results suggest that grain size‐dependent analyses of D‐ SAR s and D‐ SIR s may help to disentangle the mechanisms that generate SAR s and SIR s and may enable early detection of the effects of fragmentation on plant biodiversity.