Natural Vegetation and its Influence on Weed Populations in Neighboring Fields

Project Overview

GS03-027
Project Type: Graduate Student
Funds awarded in 2003: $9,932.00
Projected End Date: 12/31/2004
Region: Southern
State: North Carolina
Graduate Student:
Major Professor:
Dr. J. Paul Mueller
North Carolina State University

Annual Reports

Commodities

  • Agronomic: corn, peanuts

Practices

  • Crop Production: windbreaks
  • Farm Business Management: whole farm planning
  • Natural Resources/Environment: biodiversity, habitat enhancement, hedgerows, wildlife, hedges - woody
  • Pest Management: weed ecology
  • Production Systems: agroecosystems

    Abstract:

    Natural vegetation on farms provide increased biodiversity, structural diversity,
    habitat for wildlife and beneficial insects, and can act as protective buffers against
    agrochemical drift. Nevertheless, farmers frequently view these areas as potential sources
    of weeds, insect pests, and diseases. Objectives of this study were to examine weed
    species richness and abundance in cropland bordered by managed versus unmanaged
    field margins to determine if differences in weed infestation exist. Weed abundance and
    richness were measured in crop fields along permanent transects that extended from the
    field edge to the center of the crop fields. Presence/absence data for all plant species in
    the field margin were also recorded.

    Transect data from fields with margins of natural vegetation were compared to
    transect data from fields with managed margins using analysis of variance. There were
    no differences between log total abundance of weeds in crop edges adjacent to managed
    and unmanaged field margins (P=0.44). For both margin types, more weeds were found
    near the field edge than in the center of the field (1.37±0.08 to 0.52±0.07 and 1.39±0.07
    to 0.41±0.06, for managed and unmanaged field margins respectively). Species richness
    was slightly higher along crop edges of managed field margins (7.35±0.32) than crop
    edges along unmanaged field margins (6.55±0.31). Managed field margins had lower species richness than unmanaged field margins – less than half the mean number of species (5.8±0.28 versus 14.7±0.62 species, respectively).

    No association was found between plant species occurring in the field margin and
    in the crop field by generating 2 x 2 contingency tables via PROC FREQ and testing the
    association with Fisher’s exact two-sided test. Using logistic regression via PROC
    GENMOD, margin type and weed presence in the field margin were not effective
    predictors of weed occurrence in the crop field.

    Introduction

    Natural vegetation on farms such as field margins, fallow fields and wooded areas provide increased biodiversity, structural diversity, habitat for wildlife and beneficial insects, and can act as protective buffers against agrochemical drift (Kleijn 1997). Nevertheless, farmers frequently view these areas as potential sources of weeds, pests, and diseases. The relationship between managed and unmanaged field margins and adjacent cropland was examined relative to diversity, abundance, and distribution of weedy species.

    Project objectives:

    • to determine if crop edges adjacent to unmanaged field margins are associated with higher weed species richness and abundance than crop edges bordering managed areas

      to determine how weedy species are distributed in the field with respect to distance from the field edge

      to assess the presence of weedy species in the field margins and boundary areas and to determine if there is an association between weeds occurring in the field margin and the presence of the same species in the crop field

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.