PARENT SESSION
Poster Session #17: Restoration using Fire.
Tuesday, August 6. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC
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Effects of burning and mowing on arthropods in a reconstructed tallgrass prairie .
Cooper, Idelle*,1, Roeder, Elizabeth1, Brown, Jonathan1, 1 Grinnell College, Grinnell, IA
ABSTRACT- While most prairie managers use spring, dormant-season burns to promote fire-adapted native plants, more diverse communities may result from temporal and spatial variation in disturbance type. Insects are significant contributors to grassland diversity and function, and therefore should be considered when evaluating these practices. Our study examined the short-term effects of burning and mowing on arthropod abundance in a 12-year old reconstructed tallgrass prairie in central Iowa, USA. Twenty 10x10m experimental plots in a linear array were defined within a larger reconstruction, previously tilled land which was seeded with native prairie grasses and forbs in 1987 and burned annually in the spring from 1989-1996. In 1997, burning was halted on half of the plots, and, in 1999, this treatment was crossed with midsummer mowing in a two-way, randomized block design. Seven and 14 days following the mowing treatment, we measured soil conditions and sampled above- and belowground arthropods in each plot using pitfall traps, vegetation sweeping and Berlese extraction of soil cores. We evaluated effects of each treatment and their interaction on the soil measurements and insect abundance using ANOVA. Many insect groups showed no significant effects of the treatments; however, burning significantly increased abundance of aboveground Homoptera and Coleoptera, and significantly decreased belowground Araneae and Collembola. Mowing significantly decreased aboveground Coleoptera and Hymenoptera, but had no significant effects on belowground arthropods. Lower belowground insect abundance in burn plots may be due to higher soil temperature and lower soil moisture, or to changes in plant productivity, the resource base for the soil community. Aboveground mowing effects may have been caused by changes in soil surface conditions or lower nectar and pollen availability. Larger effects of mowing may appear gradually, as the yearly continuation of this treatment alters the plant community or triggers changes in decomposition processes.
KEY WORDS: tallgrass prairie, fire, mowing, arthropods