Author
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LANE L J - 5342-45-00 |
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HAKONSTON T E - COLO. STATE UNIV. |
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BOSTICK K V - LOS ALAMOS NAT. LAB. |
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Submitted to: Wildland Shrub and Arid Land Restoration Symposium Proceedings
Publication Type: Proceedings Publication Acceptance Date: 4/14/1995 Publication Date: N/A Citation: N/A Interpretive Summary: Plant productivity can be estimated by estimating plant water use. Predictions of plant water use can be based on precipitation, evapotranspiration, or transpiration. Hydrologic models can be used to calculate a water balance and to estimate evapotranspiration and transpiration. Various approaches to calculating a water balance are described in this paper. The hydrologic component of the CREAMS model was used to determine a water balance and annual values of actual transpiration for an experimental site at Rock Valley, near Mercury, NV, in the northern Mojave Desert. Above-ground net primary productivity was estimated by multiplying annual actual transpiration by a water use efficiency factor. The water balance-water use efficiency approach can be used for screening, experimental design including determining the length of records needed to sample climatic variability, and analysis of soil properties affecting plant productivity. However, it does have limitations. The main weakness of the water balance-water use efficiency approach is that it poorly represents plant physiology, stresses from nutrient deficiency, competition, herbivory, and disease, and is thus weak in reflecting feedback and the impacts of land use and management on plant productivity. Technical Abstract: Plant productivity is often estimated using precipitation, evapotranspiration, or transpiration as a predictor for plant water use. Hydrologic models are used to calculate a water balance and to estimate evapotranspiration and transpiration. The water balance approach accounts for first order environmental effects in plant productivity and is adequate efor many applications. The water balance approach can be used for screening, experimental design including determining the length of records needed to sample climatic variability, and analysis of soil properties affecting plant productivity. However, it does have limitations. Stresses due to nutrients, competition, herbivory, disease, etc. are not directly considered. The approach is process-based in terms of climate, hydrology, and soil water dynamics but is empirically based in terms of biological activities |
