Are landscapes more than the sum of their patches?

作者：With Kimberly A^*

来源：Landscape Ecology, 2016, 31(5): 969-980.

DOI：10.1007/s10980-015-0328-8

• Species-area relationship
• Species richness
• Scaling effects
• Habitat amount
• Habitat fragmentation
• Arthropods

Context The species-area relationship (SAR) is the most ubiquitous scaling relationship in ecology, yet we still do not know how different aspects of scale affect this relationship. Scale is defined by grain, extent, and focus. Focus here pertains to whether patches or landscapes are used to derive SARs.
Objective To explore whether altering the focal scale influences the resulting SAR. If the SAR is scale-invariant, patch-based and landscape-based SARs should be congruent.
Methods I fit a power-law S = cA(z)) to arthropod data obtained from an experimental landscape system, in which habitat amount and configuration (clumped vs. fragmented) of red clover (Trifolium pratense) varied among plots (256 m(2)). The scaling coefficient (z) was compared among patch-based and landscape-based SARs for congruence.
Results Patches gained species at a faster rate than landscapes (z = 0.37 vs. 0.26, respectively), producing domains of incongruity in the SAR. Landscape richness (S-L) was greater than patch richness (S-P) below 30 % habitat, but S (P) > S-L above 60 % habitat. Landscape configuration contributed to this incongruity below 30 % habitat (fragmented S-L > clumped S-L), but landscape context (whether the largest patch was embedded in a fragmented or clumped landscape) was important above 60 % habitat for understanding the SAR in this domain.
Conclusions Landscape configuration exerts both direct (<30 % habitat) and indirect (>60 % habitat) effects on the SAR. Because patch-based and landscape-based SARs may not be congruent, we should exercise care when extrapolating from patches to landscapes to make inferences about the effects of habitat loss and fragmentation on species richness.

• 出版日期2016-6