Decomposition of Blackberry and Broomsedge Bluestem as Influenced by Ozone
- J.S. Kim,
- A. H. Chappelka * and
- M. S. Miller-Goodman
Many researchers have reported on individual plant responses to O3, but few have investigated the effects of this pollutant on ecosystem function. Our investigation examined the influence of O3 on short-term (Phase I) litter decomposition of blackberry (Rubus cuneifolus Pursh.) and broomsedge bluestem (Andropogon virginicus L.), two plant species native to early successional forest communities in the southern USA. Mixed blackberry/broomsedge litter (1:1) collected from plants exposed to different levels of O3 for one growing season was placed in open-top chambers and exposed to different O3 levels of treatments for 24 wk. Litter also was incubated in microcosms in the laboratory at 25 or 30°C to determine the effects of climate change on O3-treated litter. Initial C and N concentrations of the collected foliage did not differ significantly among treatments for either species. Blackberry litter had approximately twice as much N as broomsedge, and when collected from 2X O3 chambers, had significantly greater permanganate lignin than the other treatments. Initial permanganate lignin concentration of blackberry, over all O3 treatments, correlated significantly with remaining mass of the litter mixture after 24 wk exposure. Litter decomposed more slowly in the 2X chambers than in the other treatment chambers, regardless of litter source. Elevated O3-exposed litter (2X) decomposed the slowest regardless of treatment applied. There were significant temperature and time effects observed with litter decomposition; litter incubated at 30°C decomposed faster than at 25°C. Our data suggest O3 may influence substrate quality and microbial activity, thus reducing the rate of litter decomposition in early successional forest communities.
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