The bees of Niagara: a test of the intermediate disturbance hypothesis /

This study examined the bee fauna of the Carolinian Zone in Ontario, Canada. In 2003, 15687 individuals from 152 species of bees were collected. Tliere were many rare species but few abundant species. There were three distinct bee seasons. The Niagara bee assemblage was less diverse compared to other Carolinian Zone assemblages and types of landscapes. This study also examined how anthropogenic disturbance affects the diversity of bee assemblages. The intermediate disturbance hypothesis (IDH) was tested by selecting field sites subject to low, intermediate, and high disturbance. Intermediate disturbance had the highest species richness (SR=1 15) and most bees (N=556I), followed by low disturbance (SR= 100, N=2975), then high disturbance (SR=72, N=1364), supporting the IDH. Increased species richness in areas of intermediate disturbance was due to higher abundance, possibly because more blooming flowers were found there. Bees were larger in high disturbance areas but smaller in areas of high and intermediate disturbance.

Bee Communities in Restored Landfill Sites of Niagara Region

This study examined the impact of habitat restoration on bee communities (Hymenoptera: Apidae) of the Niagara Region, Ontario, Canada. Bee abundance and diversity was studied in three restored landfill sites: the Glenridge Quarry Naturalization Site (GQNS) in St. Catharines, Elm Street Naturalization Site in Port Colborne, and Station Road Naturalization Site in Wainfleet during 2011 and 2012. GQNS represented older sites restored from 2001-2003. Elm and Station sites represented newly restored landfills as of 2011. These sites were compared to control sites at Brock University where bee communities are well established and again to other landfills where no stable habitat was available before restoration. The objective of this study is to investigate the impact of restoration level on bee abundance and diversity in restored landfill sites of the Niagara Region. Based on the increased disturbance hypothesis (InDH) and the intermediate disturbance hypothesis (IDH), I hypothesized that bee abundance and diversity will follow two patterns. First pattern according to InDH suggest that as the disturbance decrease the bee abundance and diversity will increased. Second pattern according to the IDH bee abundance and diversity will be the highest at the intermediate level of disturbance. A total of 7 173 bees were collected using pan traps and flower collections, from May to October 2011 and 2012. Bees were classified to five families, 21 genera and sub-genera, containing at least 78 species. In 2011 bee abundance was not significantly different among restoration levels while in 2012 bee abundance was significant difference among restoration level. According to family there were no significant difference in Halictidae and Apidae abundance among restoration level while Colletidae and Megachilidae abundance were varied among restoration levels. The bee species richness was highest in the newly restored sites followed by restored control sites, and then the control site. The current study demonstrates that habitat restoration results in rapid increases in bee abundance and diversity for newly restored sites, and, further, that it takes only 2-3 years for bee assemblages in newly restored sites to arrive at the same levels of abundance and diversity as in nearby control sites where bee communities are well established.

Restoration and succession of a bee community in southern St. Catharines, Ontario, within a ten-year study period

A wild bee community in southern St. Catharines, Ontario, Canada, was studied from 2003 to 2012 to analyze the effects of primary succession on abundance and diversity. At a former landfill site near Brock University, which previously contained no bees, the number of bees and bee species was expected to increase rapidly following measures to restore the site to grassy meadow habitat. The Intermediate Disturbance Hypothesis (IDH) states that over time, succession occurs. Abundance and diversity increase initially and peak when pioneers coexist with specialized species, then decline because of competitive exclusion. Alternatively, abundance and diversity may continue to increase and stabilize without declining. Bees were sampled repeatedly among years from newer restoration sites (revegetated in 2003), older restoration sites on the periphery of the former landfill (revegetated in 2000), and nearby low disturbance grassy field (i.e. control) sites. In the newer sites, bee abundance and diversity increased then decreased while in older restoration and control sites mainly decreased. This pattern of succession matches the general predictions of the IDH, although declines were at least partially related to drought. By 2006, total bee abundance levels converged among all sites, indicating rapid colonization and succession, and by 2012 diversity levels were similar among sites as well, suggesting that the bee community was fully restored or nearly so within the ten-year study period.