Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 10, 1625-1634, 2013
https://doi.org/10.5194/bg-10-1625-2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
11 Mar 2013
Decreased carbon limitation of litter respiration in a mortality-affected piñon–juniper woodland
E. Berryman1, J. D. Marshall2, T. Rahn3, M. Litvak4, and J. Butnor5 1Department of Forest and Rangeland Stewardship, Colorado State University, 1472 Campus Delivery, Fort Collins, CO, USA
2Department of Forest, Rangeland, and Fire Sciences, University of Idaho, CNR 203, Moscow, ID, USA
3Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, USA
4Department of Biology, Castetter Hall Room 133, University of New Mexico, Albuquerque, NM, USA
5USDA Forest Service, 81 Carrigan Drive, Aiken Center, Room 210, University of Vermont, Burlington, VT, USA
Abstract. Microbial respiration depends on microclimatic variables and carbon (C) substrate availability, all of which are altered when ecosystems experience major disturbance. Widespread tree mortality, currently affecting piñon–juniper ecosystems in southwestern North America, may affect C substrate availability in several ways, for example, via litterfall pulses and loss of root exudation. To determine piñon mortality effects on C and water limitation of microbial respiration, we applied field amendments (sucrose and water) to two piñon–juniper sites in central New Mexico, USA: one with a recent (< 1 yr), experimentally induced mortality event and a nearby site with live canopy. We monitored the respiration response to water and sucrose applications to the litter surface and to the underlying mineral soil surface, testing the following hypotheses: (1) soil respiration in a piñon–juniper woodland is water- and labile C-limited in both the litter layer and mineral soil; (2) piñon mortality reduces the C limitation of litter respiration; and (3) piñon mortality enhances the C limitation of mineral soil respiration. Litter respiration at both sites responded to increased water availability, yet surprisingly, mineral soil respiration was not limited by water. Consistent with hypothesis 2, C limitation of litter respiration was lower at the recent mortality site compared to the intact canopy site. Applications to the mineral soil showed evidence of reduction in CO2 flux on the girdled site and a non-significant increase on the control. We speculate that the reduction may have been driven by water-induced carbonate dissolution, which serves as a sink for CO2 and would reduce the net flux. Widespread piñon mortality may decrease labile C limitation of litter respiration, at least during the first growing season following mortality.

Citation: Berryman, E., Marshall, J. D., Rahn, T., Litvak, M., and Butnor, J.: Decreased carbon limitation of litter respiration in a mortality-affected piñon–juniper woodland, Biogeosciences, 10, 1625-1634, https://doi.org/10.5194/bg-10-1625-2013, 2013.
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