A trait-based comparison of old-field and brownfield plant-pollinator communities in north-central New Jersey

New Jersey is the most densely populated state in the U.S. and as such has many anthropogenically-modified ecosystems, including abandoned brownfields and old-fields.   These areas are increasingly being considered important greenspace for urban and suburban populations, however, their ecological function is not well understood and is likely impacted by their particular land-use history.  This study seeks to determine the influence of former land-use on plant-pollinator communities. We predicted that early-successional sites found in urban areas would have simpler (i.e., less species rich) plant communities than those of former agricultural areas because of the higher levels of fragmentation and greater environmental stressors in these areas.  Bees, an important pollinator taxon, are dependent on plant communities for survival.  Therefore we predicted a difference in bee communities based on both former land-use and plant community composition.  We predicted that bee communities would be less species rich and less abundant in former industrial areas as compared to former agricultural areas due to both the indirect effect of land use on plant diversity and abundance, and also on direct effects of land use history, such as pollution. During the summer of 2010, we established census plots in four old-field and four brownfield sites within north-central New Jersey. Bee communities were sampled using “bee bowls” (small blue, yellow and white pan traps) and the plant community was subsequently surveyed.  Results suggest that urban sites do have lower plant species richness but that bee species richness is similar across urban and rural sites.  However, there is a trend for rural sites to contain more belowground nesting bees than urban sites.