Recent reports of insect biomass decline have raised concern about the future of insect dependent
food webs and ecosystem services, such as pollination and nutrient cycling. The
causes of insect decline are difficult to pinpoint, but urbanization is a clear threat. Cities, however,
are mosaics of land uses, which likely have different effects on different insect groups. Moreover,
patterns in non-urban systems predict that urban forests will support the greatest net primary
productivity (NPP) and insect biomass. Here we examine links between land use, NPP, and insect
biomass and diversity across land uses in Raleigh, NC. First, we will develop land use–insect
biomass relationships for five urban land use types based on level of development impact
(greenways, parks, residential, commercial, and industrial areas) by sampling insects with malaise traps and pitfall traps at 30 sites in Raleigh, NC. Second, we will measure within- city NPP variation and canopy cover using geospatial data and correlate this data with insect biomass and diversity data. We hypothesize that land uses with greater canopy cover will have greater NPP and more insect biomass and diversity city-wide.
Results/Conclusions
Results/Conclusion
In our preliminary analysis, we have observed greater insect biomass in malaise traps at greenway sites. Commercial sites overall had the least amount of insect biomass. We also found that greenway sites and residential sites had the highest values of canopy cover. Mean canopy cover within 1km of sites ranged from 26-70%. We expect to find that higher areas of canopy cover will also have higher overall NPP. Together our analyses suggests that conserving canopy cover within cities may be a means to conserve insect biomass, which may have broader implications for conservation of wildlife, such as birds and other fauna, in urban spaces. Urban land uses such as greenways could serve as priority conservation areas for insects and wildlife in urban land use planning. Ultimately, the results from our study will inform insect conservation in cities in North Carolina and beyond, and will provide city planners with practical tools to identify future areas of conservation.
