Lagged effects of experimental warming and doubled precipitation on annual and seasonal aboveground biomass production in a tallgrass prairie
Sherry, R. A., E. Weng, J.A. Arnone, D.W. Johnson, D. S. Schimel, P. S. Verburg, L. L. Wallace and Y. Luo. 2008. Global Change Biology 14: 2923-2936
Abstract
Global climate change is expected to result in a greater frequency of extreme weather,
which can cause lag effects on aboveground net primary production (ANPP). However,
our understanding of lag effects is limited. To explore lag effects following extreme
weather, we applied four treatments (control, doubled precipitation, 4 C warming, and
warming plus doubled precipitation) for 1 year in a randomized block design and
monitored changes in ecosystem processes for 3 years in an old-field tallgrass prairie in
central Oklahoma. Biomass was estimated twice in the pretreatment year, and three times
during the treatment and posttreatment years. Total plant biomass was increased by
warming in spring of the treatment year and by doubled precipitation in summer.
However, double precipitation suppressed fall production. During the following spring,
biomass production was significantly suppressed in the formerly warmed plots 2 months
after treatments ceased. Nine months after the end of treatments, fall production
remained suppressed in double precipitation and warming plus double precipitation
treatments. Also, the formerly warmed plots still had a significantly greater proportion of
C4 plants, while the warmed plus double precipitation plots retained a high proportion
of C3 plants. The lag effects of warming on biomass did not match the temporal patterns
of soil nitrogen availability determined by plant root simulator probes, but coincided
with warming-induced decreases in available soil moisture in the deepest layers of soil
which recovered to the pretreatment pattern approximately 10 months after the treatments
ceased. Analyzing the data with an ecosystem model showed that the lagged
temporal patterns of effects of warming and precipitation on biomass can be fully
explained by warming-induced differences in soil moisture. Thus, both the experimental
results and modeling analysis indicate that water availability regulates lag effects of
warming on biomass production.
Key Words
ANPP, biomass, climate change, global warming, lagged effects, precipitation, soil drying, soil moisture, soil water, warming
