Print PageOdum, in his seminal Science paper, raised the question: “Are humans getting to much of a good thing?”. This rhetorical question lies at the very core of biofuels and sustainability science. Empirical studies have provided useful insight on the short-term effects of harvesting regimes on soil productivity; however, these studies reflect only a few harvest rotations for forests and long-term data for agriculture are limited. Ecosystem process models offer the opportunity to simulate the short- and long-term effects of different harvest regimes for biofuels production on long-term soil productivity. Here we use an ecosystem process model, BIOME-BGC, to examine the short- and long-term implications of harvest regime (e.g. residue removal rates, harvest frequency, etc.) on long-term soil carbon and nitrogen dynamics.
Results/Conclusions
The model simulation of NPP, soil C accumulation, and NEP agreed reasonably well with biometric and eddy-covariance measurements of these two ecosystems. For forests, he rate of change in mineral soil C decreased the greatest in the most intensive biomass removal scenarios (-0.012 and -0.072 tC ha-1 yr-1 relative to no-harvest for jack pine and sugar maple, respectively) and the smallest decrease was observed in the least intensive biomass removal scenarios (-0.002 and -0.009 tC ha-1 yr-1 relative to no-harvest for jack pine and sugar maple, respectively). The more intensive biomass removal harvest scenarios in sugar maple significantly decreased peak productivity (NPP) in the simulation period. Similar reductions in soil carbon and nitrogen were observed for corn and switchgrass. The model results compare favorably to field studies and suggest increased residue removal will decrease soil carbon and nitrogen.
