COS 1-1 - Land use alters seedling recruitment patterns along an urban-rural gradient

Monday, August 8, 2011: 1:30 PM
Ballroom B, Austin Convention Center
Benjamin T. Connor Barrie, School of Natural Resources and the Environment, University of Michigan, Ypsilanti, MI and Ines Ibanez, School of Natural Resources and Environment, University of Michigan, Ann Arbor, MI

Patterns of human land use vary as distance from an urban center increases. These changes in land use alter nutrient loads, invasive species pressure and have been associated with altered patterns in plant communities. Additionally, habitat fragmentation decreases with distance form urban centers ushering in further environmental changes (edge effects, increases in dispersal distance, etc.) that also affect plant communities. The combined impacts of habitat fragmentation and human land use patterns may further alter plant communities. Few studies however, have empirically tested the impacts of these land use changes on plant species. Here, we analyzed the impacts of land use on the growth and survival of 6 species of native and 2 species of invasive tree seedlings. We planted the seedlings at 3 sites in oak-hickory forests along a 35 km transect running from urban Ann Arbor to rural Livingston County. Over the course of the summer we measured seedling growth and mortality. In addition we measured soil moisture and light availability to account for the abiotic environment the seedlings experienced. We collected information about the type of land use surrounding each site from land cover data using GIS. To analyze our data, we constructed a hierarchical Bayesian model.


Our model shows differential growth and survival along this land use gradient. The results show that our invasive species had greater growth and survival closer to urban areas. Additionally, several large seeded native species had lower survival rates closer to urban centers. Seedling predation is a potential mechanism explaining this result. These results suggest that human land use patterns around urban centers could be an important mechanism that shapes forest communities.

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