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Warming and drying suppress microbial activity and carbon cycling in boreal forest soils
 

Summary: Warming and drying suppress microbial activity and
carbon cycling in boreal forest soils
S T E V E N D . A L L I S O N and K AT H L E E N K . T R E S E D E R
Departments of Ecology and Evolutionary Biology and Earth System Science, University of California, Irvine, 5205 McGaugh Hall,
Irvine, CA 92697, USA
Abstract
Climate warming is expected to have particularly strong effects on tundra and boreal
ecosystems, yet relatively few studies have examined soil responses to temperature
change in these systems. We used closed-top greenhouses to examine the response of soil
respiration, nutrient availability, microbial abundance, and active fungal communities to
soil warming in an Alaskan boreal forest dominated by mature black spruce. This
treatment raised soil temperature by 0.5 1C and also resulted in a 22% decline in soil
water content. We hypothesized that microbial abundance and activity would increase
with the greenhouse treatment. Instead, we found that bacterial and fungal abundance
declined by over 50%, and there was a trend toward lower activity of the chitin-degrading
enzyme N-acetyl-glucosaminidase. Soil respiration also declined by up to 50%, but only
late in the growing season. These changes were accompanied by significant shifts in the
community structure of active fungi, with decreased relative abundance of a dominant
Thelephoroid fungus and increased relative abundance of Ascomycetes and Zygomy-
cetes in response to warming. In line with our hypothesis, we found that warming

  

Source: Allison, Steven D. - Departments of Ecology and Evolutionary Biology & Earth System Science, University of California, Irvine

 

Collections: Environmental Sciences and Ecology