monitor changes in the abiotic environment in order to quantify how solar collectors or heliostats are modifying the desert environment and producing new microenvironments for organisms. Before presenting specific biotic and abiotic hypotheses, a brief discussion is necessary to delimit (a) major categories of biotic change that may occur, and (b) the biotic and/or abiotic factors that are driving variables and may change in function due to alteration. The general biotic changes are: 1. Plant photosynthesis and above-ground production will change. The driving variables governing this change will be changes in available soil water content and the physical effects of shading. Soil water will primarily be influenced by a change in evaporation rate, which is affected by shading and air movement. Shading will also reduce heat load on the plant by reducing heat flux rates between the soil and atmosphere on a diurnal basis. Therefore, changes in plant production will be a function of changes in soil water content, incoming solar radiation, environmental temperatures, and atmospheric humidity. Monitoring these variables will allow correlation of production changes with abiotic changes. Compaction effects on soil water content may also be important to consider for some soil types. 2. Plant species composition will change because the following changing factors will cause some plants to drop out and others to be enhanced, a) The degree of aboveground destruction of both plant individuals and habitat during construction phases is extremely important, as it will dictate the potential for succession of new species to occur on the site. Destruction of habitat will involve degree of disruption of the fragile desert soil surface, or "desert pavement", as well as degree of microtopographic manipulation of the site, b) The degree of soil compaction occurring during construction of the facility is important because desert perennials are known to occur in specific soils, as water relations, root oxygen requirements, and root penetration ability varies among species. Monitoring bulk density, penetration resistance, water availability, and "credibility" is suggested if extensive soil compaction occurs. c) Shading is important because it may offer a competetive advantage to species better able to utilize the greater soil water content, or less tolerant of the normally severe conditions occurring in the open desert. This will again involve monitoring changes in the water and energy fluxes occurring in the environment.
RkJQdWJsaXNoZXIy MTU5NjU0Mg==