US-EPA, Environmental Monitoring Research Laboratory, PO Box 93478, 89193, Las Vegas, NV, USA.
Environ Monit Assess. 1995 Jan;37(1-3):319-32. doi: 10.1007/BF00546898.
Studies of rainfall partitioning by shrubs, responses of shrub-dominated ecosystems to herbicide treatment, and experiments using drought and supplemental rainfall were conducted to test the hypothesis that the shrub-dominated ecosystems that have replaced desert grasslands are resistant and resilient to disturbance. Between 16 and 25% of the intercepted rainfall is channelized to deep soil storage by stemflow and root channelization. Stemflow water is nutrient enriched and contributes to the "islands of fertility" that develop under desert shrubs. Drought and rainfall augmentation experiments during the growing season after 5 consecutive years of summer drought found that (1) growth of creosotebushes, Larrea tridentata, was not significantly affected, (2) perennial grasses and forbs disappeared on droughted plots, (3) nitrogen mineralization increased in the short term, and (4) densities and biomass of spring annual plants increased on the droughted plots. Doubling summer rainfall for 5 consecutive years had less-significant effects. Coppice dunes treated with herbicide in 1979 to kill mesquite (Prosopis glandulosa) had the same frequency of occurrence of the shrub as the untreated dunes when remeasured in 1993. These data indicate that the shrub-dominated ecosystems persist because they are resistant and resilient to climatic and anthropogenic stresses.
对灌木截留降雨、灌木占主导的生态系统对除草剂处理的响应，以及干旱和补充降雨的实验进行了研究，以检验以下假设：取代沙漠草原的灌木占主导的生态系统对干扰具有抗性和弹性。截留降雨的 16%至 25%通过茎流和根导水作用被输送到深层土壤储存。茎流水富含养分，并有助于在沙漠灌木下形成“肥沃岛”。在连续 5 年夏季干旱后的生长季进行干旱和降雨增加实验发现：(1) 滨藜（Larrea tridentata）的生长没有受到显著影响；(2) 多年生草类和草本植物在干旱的地段消失；(3) 氮素矿化在短期内增加；(4) 干旱地段的春季一年生植物的密度和生物量增加。连续 5 年夏季降雨量增加的影响较小。1979 年用除草剂处理的灌丛沙丘杀死了牧豆树（Prosopis glandulosa），1993 年重新测量时，其灌木的出现频率与未处理的沙丘相同。这些数据表明，灌木占主导的生态系统得以持续存在，是因为它们对气候和人为压力具有抗性和弹性。
