SGER: Immediate Post-fire Response of Soil Biology and Pedogenic Processes at the San Dimas Lysimeter Biosequence.

过去16年在相对稳定的环境条件下进行的研究表明，生物活动对圣迪马斯（加州）研究地点的土壤形成过程有很大影响。2002年9月，一场灾难性的野火几乎烧毁了加州南部的圣迪马斯实验森林。 这场野火代表了一个极端事件，但它仍然是查帕拉尔生态系统的特征。由于火灾前的条件已被如此彻底地研究，在圣迪马斯，一个难得的机会，以促进火灾后的土壤过程的理解。 本研究将通过以下假设来测量火灾后生物群落和土壤过程的初始响应：（1）燃料负荷的细尺度变化产生了火灾严重程度的马赛克，其中表面活性土壤动物和微生物的繁殖将从最小燃烧的斑块进行;（2）深层动物在干燥的土壤中休眠，不会立即受到影响，但随着未来几个月土壤变湿，（特别是蚯蚓）将下降，因为失去了食物来源，更严重的小气候，改变土壤化学条件;和（3）最初渗入土壤的水将是高碱性的，因为它穿过覆盖的白色灰，并将导致粘土分散，土壤团聚体的不稳定性，水性粘土的冲刷，以及硅酸盐矿物风化速率的增加。 这些假设将通过详细的实地取样、现场监测和实验室分析进行检验。这些测试将确定控制火灾后土壤生态系统恢复轨迹的机制。 该研究网站将继续通过实地考察和研究机会为不同的教育机构服务。

Research under relatively stable environmental conditions of the past 16 years has shown that biological activity strongly influences soil-forming processes at the San Dimas (California) research site. In September 2002, a catastrophic wildfire burned virtually all of the San Dimas Experimental Forest in southern California. This wildfire represents an extreme event that is nevertheless characteristic of chaparral ecosystems. Because the pre-fire conditions have been so thoroughly studied as at San Dimas, a rare opportunity is presented to advance the understanding of post-fire soil processes. This research will measure the initial post-fire response of biological communities and soil processes by addressing the following hypotheses: (1) Fine-scale variation in fuel loads created a fire severity mosaic in which recolonization by surface-active soil fauna and microbes will proceed from minimally burned patches; (2) Deeper-dwelling fauna were dormant in the dry soil and not immediately impacted, but as soils wet up in the coming months, these organisms (especially earthworms) will decline because of lost food sources, more severe microclimates, and altered soil chemical conditions; and (3) The initial water leaching into the soils will be highly alkaline because it passes through overlying white ash, and will lead to clay dispersion, destabilization of soil aggregates, a flush of waterborne clay, and increased silicate mineral weathering rates. These hypotheses will be tested by detailed field sampling, in situ monitoring, and laboratory analyses. These tests will identify mechanisms that control the trajectory of soil ecosystem recovery following fires. This research site will continue to serve diverse educational institutions through field trips and research opportunities.