TY - JOUR
T1 - Forest soil carbon and nitrogen cycles under biomass harvest
T2 - Stability, transient response, and feedback
AU - Parolari, Anthony J.
AU - Porporato, Amilcare
N1 - Funding Information:
The authors thank G. Katul and D.DeB. Richter for helpful discussions and comments and acknowledge support from the U.S. Department of Energy (DOE) through the Office of Biological and Environmental Research (BER) Terrestrial Carbon Processes (TCP) program ( DE-SC0006967 ); the National Science Foundation ( DGE-1068871 , NSF-EAR-0838301 , NSF-EAR-1331846 , and NSF-EAR-1316258 ); and the United States Department of Agriculture through the Agriculture and Food Research Initiative ( 2011-67003-30222 ). We acknowledge the thoughtful comments of two anonymous reviewers.
Publisher Copyright:
© 2016 Elsevier B.V.
PY - 2016/6/10
Y1 - 2016/6/10
N2 - Biomass harvest generates an imbalance in forest carbon (C) and nitrogen (N) cycles and the nonlinear biogeochemical responses may have long-term consequences for soil fertility and sustainable management. We analyze these dynamics and characterize the impact of biomass harvest and N fertilization on soil biogeochemistry and ecosystem yield with an ecosystem model of intermediate complexity that couples plant and soil C and N cycles. Two harvest schemes are modeled: continuous harvest at low intensity and periodic clear-cut harvest. Continuously-harvested systems sustain N harvest at steady-state under net mineralization conditions, which depends on the C:N ratio and respiration rate of decomposers. Further, linear stability analysis reveals steady-state harvest regimes are associated with stable foci, indicating oscillations in C and N pools that decay with time after harvest. Modeled ecosystems under periodic clear-cut harvest operate in a limit-cycle with net mineralization on average. However, when N limitation is strong, soil C-N cycling switches between net immobilization and net mineralization through time. The model predicts an optimal rotation length associated with a maximum sustainable yield (MSY) and minimum external N losses. Through non-linear plant-soil feedbacks triggered by harvest, strong N limitation promotes short periods of immobilization and mineral N retention, which alter the relation between MSY and N losses. Rotational systems use N more efficiently than continuous systems with equivalent biomass yield as immobilization protects mineral N from leaching losses. These results highlight dynamic soil C-N cycle responses to harvest strategy that influence a range of functional characteristics, including N retention, leaching, and biomass yield.
AB - Biomass harvest generates an imbalance in forest carbon (C) and nitrogen (N) cycles and the nonlinear biogeochemical responses may have long-term consequences for soil fertility and sustainable management. We analyze these dynamics and characterize the impact of biomass harvest and N fertilization on soil biogeochemistry and ecosystem yield with an ecosystem model of intermediate complexity that couples plant and soil C and N cycles. Two harvest schemes are modeled: continuous harvest at low intensity and periodic clear-cut harvest. Continuously-harvested systems sustain N harvest at steady-state under net mineralization conditions, which depends on the C:N ratio and respiration rate of decomposers. Further, linear stability analysis reveals steady-state harvest regimes are associated with stable foci, indicating oscillations in C and N pools that decay with time after harvest. Modeled ecosystems under periodic clear-cut harvest operate in a limit-cycle with net mineralization on average. However, when N limitation is strong, soil C-N cycling switches between net immobilization and net mineralization through time. The model predicts an optimal rotation length associated with a maximum sustainable yield (MSY) and minimum external N losses. Through non-linear plant-soil feedbacks triggered by harvest, strong N limitation promotes short periods of immobilization and mineral N retention, which alter the relation between MSY and N losses. Rotational systems use N more efficiently than continuous systems with equivalent biomass yield as immobilization protects mineral N from leaching losses. These results highlight dynamic soil C-N cycle responses to harvest strategy that influence a range of functional characteristics, including N retention, leaching, and biomass yield.
KW - Biomass harvest
KW - Ecosystem nitrogen use efficiency
KW - Maximum sustainable yield
KW - Mineralization-immobilization
KW - Plant-soil feedback
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U2 - 10.1016/j.ecolmodel.2016.03.003
DO - 10.1016/j.ecolmodel.2016.03.003
M3 - Article
AN - SCOPUS:84960900803
SN - 0304-3800
VL - 329
SP - 64
EP - 76
JO - Ecological Modelling
JF - Ecological Modelling
ER -