Dear listserv members: I've been reading a lot of literature recently on the effects of fragmentation and land-use conversion from forests to agroforests and have been really troubled by what seems a pervasive issue (at least in my mind); defining the biodiversity value of a human-modified habitat type (e.g. either fragment or agroforest). Almost all studies I've reviewed partition bird communities into categories of "forest species", "rainforest specialists", "agricultural generalists", among others, and proceed to compare these among different land-uses. This is not my issue per se, but rather, I find it very circular if one uses the data/observations they collected in a study to define these groups; e.g. all species encountered in a "control" site of extensive forest were defined as forest species. These make useful and note-worthy observations but if one then proceed to include control sites in a statistical comparison then I think there is major issue with circularity. This also seems to me a very different approach than having defined a priori (e.g. from distribution lists or other literature) a set of forest-candidate species which may or may not be present in any given site surveyed. Have others here found similar issues when reviewing papers dealing with the biodiversity values of secondary forest and agricultural habitats?
Brian Campbell
