Biological Invasions

, Volume 7, Issue 3, pp 477–488

Light limitation creates patchy distribution of an invasive grass in eastern deciduous forests

Article

DOI: 10.1007/s10530-004-5171-9

Cite this article as:
Cole, P.G. & Weltzin, J.F. Biol Invasions (2005) 7: 477. doi:10.1007/s10530-004-5171-9

Abstract

Species interactions and their indirect effects on the availability and distribution of resources have been considered strong determinants of community structure in many different ecological systems. In deciduous forests, the presence of overstory trees and shrubs creates a shifting mosaic of resources for understory plants, with implications for their distribution and abundance. Determination of the ultimate resource constraints on understory vegetation may aid management of these systems that have become increasingly susceptible to invasions by non-native plants. Microstegium vimineum (Japanese grass) is an invasive annual grass that has spread rapidly throughout the understory of forests across the eastern United States since it was first observed in Tennessee in 1919. M. vimineum occurs as extensive, dense patches in the understory of eastern deciduous forests, yet these patches often exhibit sharp boundaries and distinct gaps in cover. One example of this distributional pattern was observed relative to the native midstory tree Asimina triloba (pawpaw), whereby dense M. vimineum cover stopped abruptly at the drip line of the A. triloba patch and was absent beneath the A. triloba canopy. We conducted field and greenhouse experiments to test several hypotheses regarding the causes of this observed pattern of M. vimineum distribution, including allelopathy, seed dispersal, light limitations, and soil moisture, texture, and nutrient content. We concluded that light reduction by the A. triloba canopy was the environmental constraint that prevented establishment of M. vimineum beneath this tree. Whereas overstory tree canopy apparently facilitates the establishment of this shade-tolerant grass, the interaction of overstory canopy with midstory canopy interferes with M. vimineum by reducing the availability of sunflecks at the ground layer. It is likely that other midstory species influence the distribution and abundance of other herb-layer species, with implications for management of understory invasive plant species.

Keywords

Asimina triloba Japanese grass light Microstegium vimineum non-native plants resource limitations species distribution and abundance 

Abbreviations

A. triloba

Asimina triloba

M. vimineum

Microstegium vimineum

PFD

photon flux density

TDR

time domain reflectometer

VWC

volumetric water content

Copyright information

© Springer 2005

Authors and Affiliations

  1. 1.Department of Ecology and Evolutionary BiologyThe University of TennesseeKnoxvilleUSA

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