Post-Fire Hydrology, Biogeochemistry, and Vegetation Response

0327071梅克斯纳今年9月，一场取代看台的野火烧毁了圣迪马斯实验森林（SDEF）。 SDEF拥有60年的流域水文记录和20年的流域氮输出记录。 对SDEF火灾前条件的深入了解提供了一个千载难逢的机会，可以密切调查火灾作为查帕拉尔生态系统中的生态干扰的影响。 SDEF的现有数据表明，与火灾频率较低的流域相比，火灾频率较高的流域在长时间尺度上减少了径流和无机氮的输出。 这一现有数据特别重要，因为它表明了扰动状况与生态系统对大气沉降的敏感性之间的相互作用。 更一般地说，我们的研究结果将是相关的了解生态系统中的干扰和干扰对水文和地球化学过程的影响。 我们打算在这个火灾后的环境中调查四个主要问题。 首先，我们将通过观测网络和基于过程的研究确定火灾频率对沉积物和营养物输出的相对控制。 其次，我们将调查在火灾后的环境与强大的观测网络流域水文ET的变化的影响。 该观测系统由20世纪80年代作为规定的火灾实验的一部分被烧毁的几个流域以及几个控制流域组成。 第三，我们将调查如何高速率的N沉积影响植被恢复在火灾后的环境与植被调查在SDEF和低沉积的网站在南加州。 最后，我们将调查火灾历史如何影响流域水文和地球化学输出。 我们还将为未来的研究做好准备，详细评估森林的数字高程数据，利用火灾收集地面和遥感数据，并利用加州大学捐赠的时间和设备，更广泛的含义预先存在的设施和实验框架（详细的火灾历史，流域之间的差异）提供了一个真正独特的机会，调查火灾对人类可用水量的影响和火灾对水质的影响。 由于火灾是美国西部许多生态系统的主要生态系统过程，因此更好地了解火灾对水资源和水质的影响对土地管理人员至关重要。 该研究还将提供有关空气污染和干扰如何相互作用和影响加州目前发生的大规模植被变化的信息，这些变化威胁着该地区独特的生物多样性。 . 此外，圣迪马斯实验森林位于加州南部，人口多样，本科院校众多，为接触环境科学领域代表性不足的群体提供了绝佳的机会：城市人口和少数民族。 加州大学、滨江大学和长滩州立大学都主要为少数族裔人口服务。

0327071MeixnerA stand-replacing wildfire burned through the San Dimas Experimental Forest (SDEF) this past September. The SDEF has a 60-year record of watershed hydrology and a 20-year record of watershed nitrogen export for several watersheds. The intense understanding of pre-fire conditions at the SDEF presents a once in a lifetime opportunity to closely investigate the impacts of fire as an ecological disturbance in a chaparral ecosystem. Existing data at SDEF indicates that watersheds with more frequent fires have reduced streamflow and inorganic nitrogen export on long timescales compared to watersheds with less frequent fires. This existing data is especially important because it indicates an interaction between disturbance regime and the susceptibility of ecosystems to atmospheric deposition. More generally our results will be relevant to understanding disturbance in ecosystems and disturbance influences on hydrologic and biogeochemical processes. We intend to investigate four major questions in this post-fire environment. First, we will determine the relative control of fire frequency on sediment and nutrient export with an observational network and process based studies. Second, we will investigate the impact of changes in ET on watershed hydrology in the post-fire environment with a robust observation network. This observation system consists of several watersheds that were burned during the 1980's as part of a prescribed fire experiment as well as several control watersheds. Third, we will investigate how the high rates of N deposition influence vegetation recovery in the post-fire environment with vegetation surveys at SDEF and at a low deposition site in southern California. Finally, we will investigate how fire history affects watershed hydrologic and biogeochemical export. We will also prepare the ground for future studies with detailed assessment of digital elevation data at the forest taking advantage of fire to collect both on the ground and remotely sensed data as well as with preliminary measurements of ET with an eddy-flux system with time and equipment donated by the University of California, Irvine.Broader ImplicationsThe pre-existing facilities and experimental framework (detailed fire history with differences between watersheds) provide a truly unique opportunity to investigate the impact of fire on the amount of water available for human use and the impacts of fire on water quality. Since fire is such a dominant ecosystem process in many ecosystems of the western United States, better information on the impact of fire on water resources and water quality is critical information for land managers. The research will also provide information on how air pollution and disturbance interact and influence the large-scale vegetation change currently occurring in California that threatens the unique biodiversity of the region. . Additionally the location of the San Dimas Experimental Forest in southern California with its diverse population and numerous undergraduate institutions provide a perfect opportunity for outreach to underrepresented groups in the environmental sciences: urban populations and minorities. The University of California, Riverside and Long Beach State University both serve predominantly minority populations.