Da. Kelt et al., Scale dependence and scale independence in habitat associations of small mammals in southern temperate rainforest, OIKOS, 85(2), 1999, pp. 320-334
Although field biologists commonly employ methodologies that either are tim
e-tested or are believed (usually for very good reason) to be suitable to t
he conditions that are encountered, it is rare that results generated using
differing methods can be compared on a single fauna. We reanalyze data fro
m three studies conducted on the small mammal fauna of Valdivian temperate
rainforests in southern Chile. By restricting our analyses to a relatively
homogeneous habitat type we avoid many problems associated with studies ove
r large spatial scales, such as increased species richness via beta diversi
ty. The studies involve a temporal transect, an elevational transect, and a
latitudinal transect, and comprise a spatially nested series. Because thes
e studies differed in their initial objectives, they employed different met
hodologies, both in the field and during subsequent data analysis. At all s
cales of analysis there is notable overlap in habitat use by all species. A
lthough we observed some seasonal differences in habitat use by species, th
ese were not substantial and involved a small subset of the species. At a l
ocal scale, numerically dominant species selected non-random microhabitats
but co-occurred with other species more frequently than expected by chance.
At a larger spatial scale species appeared to select large subsets of the
macrohabitat (i.e., "mesohabitat"), providing patterns suggestive of appare
nt competition among species. At an even larger spatial scale, that of temp
erate southern South America, we predict that species assemblages will agai
n exhibit positive associations. Thus, views on the importance of competiti
on and other biological processes depend critically on the spatial and temp
oral scales over which observations are made.