@article {50736, title = {Disposition of rainwater under creosotebush}, journal = {Hydrological Processes}, volume = {17}, year = {2003}, note = {//NMSU//LTER IV//}, month = {2003}, pages = {2555-2566}, abstract = {

In desert shrubland ecosystems water and nutrients re concentrated beneath shrub canopies in {\textquoteright}resource islands{\textquoteright}. Rain falling onto these islands reaches the ground as either stemflow or throughfall and then either infiltrates into the soil or runs off as overland flow. This study investigates the partitioning of rainwater between stemflow and throughfall in the first instance and between infiltration and runoff in the second. Two series of 40 rainfall simulation experiments were performed on 16 creosotebush shrubs in the Jornada Basin, New Mexico. The first series of experiments was designed to measure the surface runoff and was performed with each shrub in its growth position. The second series was designed to measure stemflow reaching the shrub base and was conducted with the shrub suspended above the ground. The experimental data show that once equilibrium is achieved, 16\% of the rainfall intercepted by the canopy or 6.7\% of the rain falling inside the shrub area (i.e., the area inside the shrubs circumscribing ellipse) is funneled to the shrub base as stemflow. This redistribution of the rainfall by stemflow is a function of the ratio of canopy area (i.e., the area covered by the shrub canopy) to collar area (i.e., a circular area centered on the shrub base), with stemflow rate being positively correlated and throughfall rate being negatively correlated with this ration. The surface runoff rate expressed as a proportion of the rate at which rainwater arrives at a point (i.e., stemflow rate plus throughfall rate) is the runoff coefficient. A multiple regression reveals that 75\% of the variance in the runoff coefficient can be explained by three independent variables: the rainfall rate, the ratio of the canopy area to the collar area, and the presence or absence of subcanopy vegetation. Although the last variable is a dummy variable, it accounts for 66.4\% of the variance in the runoff coefficient. This suggests that the density and extent of the subcanopy vegetation is the single most important control of the partitioning of rainwater between runoff and infiltration beneath creosotebush. Although these findings pertain to creosotebush, similar findings might be expected for other desert shrubs that generate significant stemflow and have subcanopy vegetation. Copyright {\textcopyright} 2003 John Wiley \& Sons, Ltd.

}, keywords = {article, articles, creosotebush, hydrology, creosotebush,also SEE , hydrology, creosotebush, hydrology, infiltration, hydrology, overland flow, hydrology, resource islands, hydrology, stemflow, journal, journals, rainfall simulation, hydrology, rainwater, resource islands, hydrology}, doi = {10.1002/hyp.1272}, url = {files/bibliography/JRN00382.pdf}, author = {Athol D. Abrahams and A.J. Parsons and John Wainwright} } @article {52145, title = {A simulation model of primary production and carbon allocation in the creosotebush (Larrea tridentata [DC.] Cov.)}, journal = {Ecology}, volume = {59}, number = {1}, year = {1978}, note = {//NMSU//US-IBP//}, month = {1978}, pages = {37-52}, abstract = {A preliminary simulation model of primary productivity and carbon allocation in creosotebush (Larrea tridentata [DC] Cov.) is described. The model utilizes a systems approach in which movement of assimilate within the plant is in response to changes in source-sink strengths of leaves, stems, roots, early reproductive buds, maturing reproductive buds, flowers, and fruits. Two distinct compartments are defined per organ or developmental stage to separate assimilate into a pool fraction (labile or translocatable) and a structural fraction (nonlabile). The changes in magnitude (within upper and lower limits) of a pool compartment during the course of a simulation (i.e., growth and development of the plant) are a function of the rates of maintenance respiration and growth as well as a priority scheme governing allocation of assimilates; the increases and decreases in dry weight of a structural compartment are a function of aging and the magnitude of its associated pool (which determines structural growth and physiological death). A 1-yr simulation of a hypothetical Larrea plant shows that the model exhibits a reasonable behavior, although no validation is attempted at this stage in its development. The heuristic value of the model is illustrated in the sensitivity analysis, which shows the need for detailed knowledge of "priority" carbon movement during both vegetative and reproductive growth periods, the importance of substrate controlled respiration rates, and the need for further studies of the dynamics of labile pools in the plant. The model has been an excellant tool in our initial attempt to integrate the voluminous information on Larrea into a complete functional description of the autecology of the species. Further refinement of this model, as data from our current research and that of other investigators become available, should lead us to a better understanding of the ecological role of Larrea in desert ecosystems.}, keywords = {article, articles, creosotebush,also SEE , journal, journals, Larrea, carbon allocation, model,carbon allocation,Larrea, model,primary production,Larrea, primary production,Larrea, shrub, Larrea}, author = {Gary L. Cunningham and J. F. Reynolds} }