Annual Removal of Aboveground Plant Biomass Alters Soil Microbial Responses to Warming.
Clipping (i.e., harvesting aboveground plant biomass) is common in agriculture and for bioenergy production. However, microbial responses to clipping in the context of climate warming are poorly understood. We investigated the interactive effects of grassland warming and clipping on soil properties and plant and microbial communities, in particular, on microbial functional genes. Clipping alone did not change the plant biomass production, but warming and clipping combined increased the C4peak biomass by 47% and belowground net primary production by 110%. Clipping alone and in combination with warming decreased the soil carbon input from litter by 81% and 75%, respectively. With less carbon input, the abundances of genes involved in degrading relatively recalcitrant carbon increased by 38% to 137% in response to either clipping or the combined treatment, which could weaken long-term soil carbon stability and trigger positive feedback with respect to warming. Clipping alone also increased the abundance of genes for nitrogen fixation, mineralization, and denitrification by 32% to 39%. Such potentially stimulated nitrogen fixation could help compensate for the 20% decline in soil ammonium levels caused by clipping alone and could contribute to unchanged plant biomass levels. Moreover, clipping tended to interact antagonistically with warming, especially with respect to effects on nitrogen cycling genes, demonstrating that single-factor studies cannot predict multifactorial changes. These results revealed that clipping alone or in combination with warming altered soil and plant properties as well as the abundance and structure of soil microbial functional genes. Aboveground biomass removal for biofuel production needs to be reconsidered, as the long-term soil carbon stability may be weakened.


OBJECTIVE
Global change involves simultaneous alterations, including those caused by climate warming and land management practices (e.g., clipping). Data on the interactive effects of warming and clipping on ecosystems remain elusive, particularly in microbial ecology. This study found that clipping alters microbial responses to warming and demonstrated the effects of antagonistic interactions between clipping and warming on microbial functional genes. Clipping alone or combined with warming enriched genes degrading relatively recalcitrant carbon, likely reflecting the decreased quantity of soil carbon input from litter, which could weaken long-term soil C stability and trigger positive warming feedback. These results have important implications in assessing and predicting the consequences of global climate change and indicate that the removal of aboveground biomass for biofuel production may need to be reconsidered.
State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, China Institute for Environmental Genomics, University of Oklahoma, Norman, Oklahoma, USA Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA.
Kai
K
Xue
Institute for Environmental Genomics, University of Oklahoma, Norman, Oklahoma, USA Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA.
Mengting M
MM
Yuan
Institute for Environmental Genomics, University of Oklahoma, Norman, Oklahoma, USA Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA School of Mineral Processing and Bioengineering, Central South University, Changsha, Hunan, China.
Jianping
J
Xie
Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA.
Dejun
D
Li
Institute for Environmental Genomics, University of Oklahoma, Norman, Oklahoma, USA Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA.
Yujia
Y
Qin
Institute for Environmental Genomics, University of Oklahoma, Norman, Oklahoma, USA Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA.
Lauren E
http://orcid.org/0000-0002-2574-2225
LE
Hale
Institute for Environmental Genomics, University of Oklahoma, Norman, Oklahoma, USA Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA.
Liyou
L
Wu
Institute for Environmental Genomics, University of Oklahoma, Norman, Oklahoma, USA Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
Ye
Y
Deng
Institute for Environmental Genomics, University of Oklahoma, Norman, Oklahoma, USA Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA.
Zhili
Z
He
Institute for Environmental Genomics, University of Oklahoma, Norman, Oklahoma, USA Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA.
Joy D
JD
Van Nostrand
Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA.
Yiqi
Y
Luo
Center for Microbial Ecology, Michigan State University, East Lansing, Michigan, USA.
James M
JM
Tiedje
State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, China Institute for Environmental Genomics, University of Oklahoma, Norman, Oklahoma, USA Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA School of Civil Engineering and Environmental Sciences, University of Oklahoma, Norman, Oklahoma, USA Earth and Environmental Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA jzhou@ou.edu.
Jizhong
J
Zhou
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