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MICROHABITAT REVIEWED: ANALYSIS OF A PARADIGM
Citation:
Jorgensen*, E E. MICROHABITAT REVIEWED: ANALYSIS OF A PARADIGM. Presented at Conference of The American Society of Mammalogists, Missoula, MT, 6/16-20/01.
Description:
Small mammal microhabitat partitioning research has greatly influenced vertebrate community ecologists. It is not a stretch to assert that there exists a 'microhabitat paradigm' among small mammal specialists; sympatry among small mammal species is enabled by differential use of microhabitat. However, several studies have failed to detect microhabitat partitioning and research has consistently indicated that microhabitat phenomena do not scale to be expressed over larger spatial areas (i.e., macrohabitat). I explore possible reasons for these difficult to reconcile observations by reviewing and tabulating data from 68 published papers. The meaning of the term 'microhabitat' has subtly changed since 1969. Early studies hypothesized that small mammals "subdivide habitat". Later studies inaccurately portrayed these early studies as "microhabitat" studies and also refined the definition of microhabitat to include only physical structure. Contrary to prevailing belief, many of the studies underlying the microhabitat paradigm were conducted with modest levels of effort. Fifty percent of studies used #3 trapping grids, #5000 trap nights, or #3 co-occurring species. Fifty-nine percent of studies were conducted in only 1 type of vegetation and only 24% of studies measured vegetation to a spatial scale finer that 45 m2. Fifty percent of the published data is concentrated among 8 species. This review demonstrates that our existing knowledge of small mammal microhabitat partitioning is highly concentrated among small-scale studies, conducted with modest intensity, that measure microhabitat at inappropriate spatial scales. This concentration of knowledge is, I believe, an insufficient foundation upon which to accept microhabitat partitioning as a widely generalizable phenomenon. The views expressed are those of the author and do not necessarily reflect the views and policies of the U.S. Environmental Protection Agency (EPA).