Disalvo Angela C, Hart Stephen C
School of Forestry, College of Ecosystem Science and Management and Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff 86011, USA.
Environ Manage. 2002 Nov;30(5):678-91. doi: 10.1007/s00267-002-2719-2.
Humans have severely impacted riparian ecosystems through water diversions, impoundments, and consumptive uses. Effective management of these important areas is becoming an increasingly high priority of land managers, particularly as municipal, industrial, and recreational demands for water increase. We examined radial tree growth of four riparian tree species ( Pinus jeffreyi, Populus trichocarpa, Betula occidentalis, and Pinus monophylla) along Bishop Creek, California, and developed models relating basal area increment (BAI) and relative basal area increment (RBAI) to climatic and stream flow variables. Between years 1995-1999, univariate regression analysis with stream flow explained 29 to 61% of the variation in BAI and RBAI among all species except P. trichocarpa; growth by P. trichocarpa was not significantly related to stream flows over this period. Stepwise linear regression indicated that species responded differently to climatic variables, and models based on these variables explained between 33 to 86% of variation in BAI and RBAI during the decade of the 1990s. We examined branch growth of P. trichocarpa for sensitivity to differences in stream flow regimes and found that annual branch growth did not vary between a high- and low-flow site, but that annual branch growth was significantly higher in wet years with greater stream flows. Our results support the establishment of site-specific management goals by land managers that take into account all of the important tree species present in riparian ecosystems and their differential responses to altered hydrologic condition. Instream flow requirements for maintaining tree growth and vigor are only one of the species-specific responses that need to be evaluated, and these assessments should attempt to separate experimentally stream-flow (managed) controls from climatic (unmanaged) controls on growth.
人类通过引水、蓄水和消耗性用水等方式对河岸生态系统造成了严重影响。对这些重要区域进行有效管理正日益成为土地管理者的首要任务，尤其是随着市政、工业和娱乐用水需求的增加。我们研究了加利福尼亚州毕晓普溪沿岸四种河岸树种（杰弗里松、毛果杨、西方桦和单叶松）的径向树木生长情况，并建立了将断面积生长量（BAI）和相对断面积生长量（RBAI）与气候和溪流流量变量相关联的模型。在1995年至1999年期间，除毛果杨外，所有物种中，单变量回归分析表明，溪流流量可解释BAI和RBAI变化的29%至61%；在此期间，毛果杨的生长与溪流流量无显著相关性。逐步线性回归表明，不同物种对气候变量的反应不同，基于这些变量的模型可解释20世纪90年代十年间BAI和RBAI变化的33%至86%。我们研究了毛果杨的树枝生长对不同溪流流量状况差异的敏感性，发现高流量和低流量站点之间的年树枝生长量没有差异，但在溪流流量较大的湿润年份，年树枝生长量显著更高。我们的研究结果支持土地管理者制定因地制宜的管理目标，这些目标应考虑到河岸生态系统中所有重要的树种及其对水文条件变化的不同反应。维持树木生长和活力所需的河道内流量要求只是需要评估的特定物种反应之一，这些评估应尝试通过实验将生长的溪流流量（可控）控制与气候（不可控）控制区分开来。
