BIRD AND MAMMAL DIVERSITY ON WOODY BIOMASS PLANTATIONS IN NORTH-AMERICA

In this paper, recent studies of birds and small mammals inhabiting Po puhus (hybrid poplar and cottonwood) plantations are summarized. Plant ations provide habitat at least as favorable for native birds and mamm als (as evidenced by overall density, species richness, and species co mposition) as agricultural croplands. However, by the same measures, p lantation habitat is poorer quality than natural or semi-natural fores t. Bird and small mammal species composition on plantations is a mixtu re of openland (crop and grassland) and forest species that is unique compared to other nearby habitats, and does not resemble that of eithe r grasslands or forests. Plantations may not function as forest at eit her habitat or landscape scales. For highly mobile animals such as bir ds, landscape composition plays a central role in determining occupanc y of plantations. For less mobile organisms, within-plantation habitat quality is more critical. Sources of non-uniformity in plantation veg etation are important determinants of occupancy. Although unplanned va riation in vegetation structure occurs on some plantations, assuring t he presence of heterogeneity may require specific planning. There is n o evidence of altered population interactions (nest predation or paras itism, small-mammal population performance, or interchange among local populations) as a result of plantation establishment. (C) 1998 Elsevi er Science Ltd. All rights reserved.