Forest landscape patterns shaped by interactions between wildfire and sudden oak death disease
Forest landscape patterns shaped by interactions between wildfire and sudden oak death disease
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DOI：
10.1016/j.foreco.2021.118987
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发表时间：
2021-04
影响因子：
3.7
通讯作者：
Yinan He;Gang Chen;R. Cobb;K. Zhao;R. Meentemeyer
中科院分区：
文献类型：
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作者：
Yinan He;Gang Chen;R. Cobb;K. Zhao;R. Meentemeyer
森林生态系统日益受到一系列树木死亡事件的影响，这些事件可能永久性地改变森林的功能特征并破坏其生态系统服务。虽然对单个森林干扰进行了很好的研究，但多种干扰与森林景观空间格局变化之间的相互作用很少被量化。在这项研究中，我们的目的是分析野火在加州大索尔生态地区对疫霉（phytophthora ramorum）传播的作用，疫霉是一种导致橡树猝死的入侵病原体，是1000公里沿海、易发火灾的混合针叶树、常绿硬木和林地死亡的最重要驱动因素。我们研究了两个特定的问题，这些干扰的影响在景观尺度：(i)是否p的比率。森林大火后树木死亡率的变化？野火之后，疾病导致的持续死亡在多大程度上改变了森林分布？为了回答这些问题，我们分析了火灾后烧伤严重程度的遥感衍生产品和疾病导致的树木死亡率地图。烧伤和未烧伤地区的烧伤严重程度和火灾后疾病死亡率的量化为统计假设检验提供了参考条件。统计和三种景观格局分析（面积、形状和隔离）的结果表明，野火在这种入侵病原体的重新出现中发挥了重要作用。首先，野火后疾病导致的死亡率与烧伤严重程度呈负相关，这表明在火灾后森林恢复期间，一些由火灾驱动的疾病得到了控制。其次，在未燃烧区域，疾病与距离火灾边界的距离呈正相关，表明火灾对疾病的影响延伸到未燃烧区域，而随着距离烧伤距离的增加而减弱。最后，野火减少了健康树木斑块的面积、边缘密度和隔离度，并且在植被恢复8年后，这三个指标中的任何一个都没有恢复到火灾前的水平。鉴于疾病导致死亡率的普遍存在，火灾的重要性和频率，以及疫霉菌在广泛地理区域的归化，这些火-病相互作用有可能影响加利福尼亚和俄勒冈州数百万英亩森林荒地的森林结构和疾病动态。
Forest ecosystems are increasingly affected by a range of tree mortality events, which may permanently alter forest functional traits and disrupt their ecosystem services. While individual forest disturbances are well studied, interactions between multiple disturbances and changes of spatial patterns of forested landscapes are rarely quantified. In this study, we aim to analyze the role of wildfire in the Big Sur ecoregion of California on the spread ofPhytophthora ramorum, an invasive pathogen which causes sudden oak death, the most important driver of mortality across 1000 km of coastal, fire-prone mixed conifer, evergreen hardwood, and woodlands. We investigated two questions specific to the impacts of these disturbances at the landscape scale: (i) did rates ofP. ramorumcaused tree mortality change after wildfire? (ii) Following the wildfire, to what degree did the continued disease-driven mortality alter forest distribution? To answer these questions, we analyzed remote-sensing-derived products of post-fire burn severity and maps of disease-driven tree mortality. Quantification of burn severity and post fire disease mortality for the burned and unburned areas provided reference conditions for statistical hypothesis tests. The results from statistical and three landscape pattern analyses (area, shape, and isolation) suggest a significant role of wildfire in the reemergence of this invasive pathogen. First, rates of disease caused mortality after wildfire was negatively associated with burn severity suggesting some fire-driven containment of disease during post-fire forest recovery. Second, disease was positively correlated with the distance to fire boundary in unburned areas suggesting the effects of fire on disease extended into unburned areas while attenuating with distance from the burn. Lastly, wildfire reduced area, edge density and isolation of healthy tree patches and these effects did not recover to pre-fire levels for any of the three metrics after eight years of vegetation recovery. Given the widespread prevalence of disease-driven mortality, the importance and frequency of fire, as well as the naturalization ofPhytophthora ramorumacross a broad geographic area, these fire-disease interactions have potential to shape forest structure and disease dynamics across millions of acres of forested wildlands in California and Oregon.