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Tong Zhai Rabi H. Mohtar Andrew R. Gillespie Guntram R. von Kiparski Keith D. Johnson Michael Neary 《Agroforestry Systems》2006,66(3):243-257
Tree effects on understory pasture growth in a silvopastoral system were modeled by explicit simulation of tree canopy light
and rainfall interception, evapotranspiration, and nutrient uptake. The algorithms to model these effects were incorporated
into a multispecies grazing simulation model, GRASIM, to form the Silvopasture GRASIM model (SGRASIM). The new model was evaluated
using forage biomass data and soil moisture data collected from a silvopasture field experiment with black walnut (Juglans nigra L.). The SGRASIM model performed well in simulating the growth of three competing dominant forage species (orchardgrass [Dactylis glomerata L.], Kentucky bluegrass [Poa pratensis L.], and tall fescue [Festuca arundinacea (Schreb.)] in the pasture both under tree canopy and in open pasture (linear regression of observed on simulated biomass
for the species gave r
2 values above 0.97). Model growth parameters for forage under tree canopy, compared with those for an open pasture, bear testament
to the shading effects from the forest canopy in terms of reduced photosynthetic efficiency, increased leaf area ratio, and
photosynthate partitioned to aboveground biomass. The new model reasonably followed the soil moisture time series in the upper
soil layer (0–30 cm), where the bulk of the forage roots reside. 相似文献
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