EFFECTS OF REED CANARY GRASS (PHALARIS ARUNDINACEA) ON TERRESTRIAL ARTHROPOD 
ABUNDANCE, BIOMASS, AND DIVERSITY IN UPPER MIDWESTERN RIPARIAN WET MEADOWS.

Melissa S. Meier1, 2, Eileen M. Kirsch1, and Robin Tyser2.
1U.S. Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, 
WI 54603, 2University of Wisconsin-La Crosse, La Crosse, WI 54601.

Reed canary grass occurs in temperate regions of the northern hemisphere and is 
native to North America.  However, cultivated Eurasian strains, introduced to 
the United States by European settlers, blended with the native varieties and 
made reed canary grass more aggressive.  Reed canary grass tolerates a wide 
range of growing conditions, and is considered invasive because it can quickly 
develop into dense, monotypic stands that displace native vegetation.  Invasive 
plant species, such as reed canary grass, have altered grasslands and wetlands 
by reducing plant diversity and structure.  Studies have shown that plant 
diversity and arthropod diversity are positively correlated.  Arthropods are 
abundant in terrestrial habitats and are critical components of ecosystems.  
However, little is known about how arthropods respond to the presence of reed 
canary grass.  The purpose of this research was to determine if abundance, 
biomass, and diversity of arthropods were higher in areas dominated by diverse, 
native vegetation compared to areas dominated by reed canary grass.  Arthropod 
sampling was conducted in July 2001 and July 2002 at 12 and 13 wet-
meadow/grassland plots, respectively, in southeastern Minnesota and southwestern 
Wisconsin.  The plots varied in size from 4.5 ha to 16.5 ha and ranged from low 
to high reed canary grass abundance.  Arthropods were sampled with sweep-nets at 
randomly selected points on each plot, which represented one sweep-net sample 
per 1.5 ha of plot (n=73 in 2001, and n=80 in 2002).  For each sample, the 
number of arthropods, the wet weight (g) of the total sample, and the number of 
individuals in each Order were recorded.  Preliminary results suggested that 
average arthropod numbers were similar among the plots, but average sample 
biomass tended to be slightly higher in plots with low and intermediate levels 
of reed canary grass.  Also, the average number of Orders represented in samples 
for each plot were similar, but there may be differences in the average number 
of individuals per Order related to reed canary grass abundance on the plots.  
Additional analysis of the 2001 data and analysis of the 2002 data are currently 
in progress.     

Keywords: invasive species, Phalaris arundinacea, reed canary grass, terrestrial 
arthropods, wet meadows