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Morrison deer and invasive plants in suburban forests 2021 Ecoscience


Morrison, Janet (2021), Morrison deer and invasive plants in suburban forests 2021 Ecoscience, Dryad, Dataset,


Fragmented suburban forests of the northeastern US are challenged by abundant white-tailed deer and nonindigenous plant invasions. Deer browsing/grazing pressure varies among sites, potentially affecting herbivory on nonindigenous plants and their invasion success. We aimed to identify a useful deer pressure indicator for suburban forests and then use it to relate deer pressure to grazing on and abundance of two herbaceous invaders, Microstegum viminuem and Alliaria petiolata. We compared three indicators: fecal pellet accumulation rate, deer browse on indigenous woody plants, and indigenous shrub layer cover. The pellet method produced estimates generally far below the region’s known deer density. Browse rates and shrub layer cover were negatively correlated, and correlations of the three indicators with evidence of deer pressure from a subsequent 6.5-year exclosure experiment supported shrub layer cover as the better choice. Using that measure in ten forests, we detected a weak pattern of more grazed stands under greater deer pressure, but few plants per stand were grazed; any negative influence of deer on these species was limited to individuals, without population effects. Alliaria petiolata abundance was unrelated to deer pressure, but M. vimineum abundance was greater in forests with more deer pressure, suggesting facilitation of its invasion.


Data were collected in field sites in central New Jersey, USA, entered and managed in Excel files, and analyzed with SAS and R.

Usage Notes

A ReadMe file with extensive annotation is provided:

"README for Morrison_DeerAndInvasives_2021_Ecoscience.txt"


National Science Foundation, Award: NSF-DEB 1257833