Climate change alters seedling emergence and establishment in an old-field ecosystem.
BACKGROUND
Ecological succession drives large-scale changes in ecosystem composition over time, but the mechanisms whereby climatic change might alter succession remain unresolved. Here, we asked if the effects of atmospheric and climatic change would alter tree seedling emergence and establishment in an old-field ecosystem, recognizing that small shifts in rates of seedling emergence and establishment of different species may have long-term repercussions on the transition of fields to forests in the future.


RESULTS
We introduced seeds from three early successional tree species into constructed old-field plant communities that had been subjected for 4 years to altered temperature, precipitation, and atmospheric CO(2) regimes in an experimental facility. Our experiment revealed that different combinations of atmospheric CO(2) concentration, air temperature, and soil moisture altered seedling emergence and establishment. Treatments directly and indirectly affected soil moisture, which was the best predictor of seedling establishment, though treatment effects differed among species.


CONCLUSIONS
The observed impacts, coupled with variations in the timing of seed arrival, are demonstrated as predictors of seedling emergence and establishment in ecosystems under global change.
Classen
Aimée T
AT
Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, Tennessee, United States of America. aclassen@utk.edu
Norby
Richard J
RJ
Campany
Courtney E
CE
Sides
Katherine E
KE
Weltzin
Jake F
JF
D001272:Atmosphere; D002245:Carbon Dioxide / Q000032:analysis; D057231:Climate Change; D017753:Ecosystem; D014197:Trees / Q000254:growth & development*
D002245:Carbon Dioxide