The Effects of Land Management on Fire Regimes and Landscape-Scale Vegetation Patterns in the Mountain Ranges of Southern California

加州南部的陆地生态系统受到周期性野火的影响，但历史上的火灾制度已经通过灭火而改变，并从夏季的自然闪电点火转变为人为点火源和极端火灾天气期间的灾难性火灾。一个改变了的火制度对植被结构，组成和景观格局，以及野火对人类的危害有着深远的影响。在拟议的研究中，一个模拟景观动态的计算机模型（LANDIS，由大卫Mladenoff和其他人开发）将被用来预测火灾频率，强度和大小的变化对植物群落演替的影响，以及由此产生的植被组成和结构的模式在南加州的区域尺度。这些变化的火灾制度可能会导致灭火，人为点火，土地利用的变化，气候变化，或这些之间的相互作用。它们可能导致当地植物物种或群落的丧失（否则被认为是广泛的，而不是罕见的），栖息地模式的变化，对具有有限的传播能力或特定栖息地要求的动物可能产生负面影响，以及对火灾制度的反馈（或多或少，易燃景观）模拟建模用于预测空间和时间尺度上的变化，对于这些变化，实验是不可能的，并且监测数据在空间上是稀疏的，时间以下将通过模拟实验解决：火灾之间的间隔增加导致大规模的变化，森林和查帕拉尔物种优势和景观年龄结构？预测的变化发生在哪里？模型结果将通过以下方式进行评估：a）测试重复模型运行产生的景观格局指标差异的显著性; B）与火灾历史图进行比较; c）与文献中报告的特定地点植被动态格局进行比较，并通过重新调查ca.首次调查的植被地块确定。1930.模型预测可以为今后生态系统动态的地理分层长期监测提出建议。

The terrestrial ecosystems of southern California are subject to periodic wildfires, but fire regimes have been altered historically by fire suppression, and a shift from natural lightning ignitions in summer to human-caused ignition sources and catastrophic fires during extreme fire weather. An altered fire regime has a profound influence on vegetation structure, composition and landscape pattern, and wildfire hazards for humans. In the proposed research, a computer model that simulates landscape dynamics (LANDIS, developed by David Mladenoff and others) will be used to predict the effects of changes in fire frequency, intensity and size on plant community succession, and on the resulting patterns of vegetation composition and structure at a regional scale in southern California. These changes to the fire regime may result from fire suppression, anthropogenic ignition, land use change, climate change, or interactions among these. They could result in local loss of plant species or communities (that are otherwise thought of as widespread, not rare), changes in habitat pattern with potentially negative effects on animals with limited dispersal ability or specific habitat requirements, and feedbacks to the fire regime (a more, or less, flammable landscape).Simulation modeling is used to predict changes over spatial and temporal scales for which experimentation is impossible and monitoring data are sparse in space and time. The following will be addressed through modeling experiments: Do increased intervals between fires lead to large-scale changes in forest and chaparral species dominance and landscape age structure? Where do the predicted changes occur? The model results will be evaluated by a) testing for the significance of the difference in landscape patterns metrics resulting from replicated model runs; b) comparison with fire history maps; and c) comparison with site-specific patterns of vegetation dynamics reported in the literature and determined through re-survey of vegetation plots first surveyed in ca. 1930. Model predictions can yield recommendations for geographicallystratified long-term monitoring of future ecosystem dynamics.