Climate change is projected to significantly affect the vulnerability of forests across the western United States to wildfires, insects, disease, and droughts. Here, we provide recent mortality estimates for large trees for 53 species across 48 ecological sections using an analysis of 23,215 Forest Inventory plots and a Random Forest classification model. Models were also used to predict mortality in future FIA inventories under the RCP 4.5 emissions scenario. Model performance indicated species identity as the most important predictor of mortality under both current and future scenarios, with contributions from climate and soil variables. Our results show relatively high levels of recent mortality in the Middle and Southern Rocky Mountains driven by high mortality in Populus tremuloides, Pinus contorta, Pinus albicaulis, and Abies lasiocarpa. Low levels of mortality were observed in several species, with <1% annual mortality observed throughout all other sections. Future mortality was predicted to increase significantly for most species and correlated well with recent mortality at the species level, but not at the plot level. These results suggest that future attempts to model or predict widespread forest mortality would benefit from more research on vulnerable species and that significant mortality events in some species may not be important for dynamics across all systems.

中文翻译：

---

使用森林清单和随机森林分类预测美国西部森林的树木死亡率

预计气候变化将严重影响美国西部森林遭受野火，昆虫，疾病和干旱的脆弱性。在这里，我们使用23,215份森林资源清单图和随机森林分类模型，提供了48个生态区中53种树种的大树的近期死亡率估算。还使用模型来预测RCP 4.5排放情景下未来国际汽联清单中的死亡率。模型的性能表明，在气候和土壤变量的影响下，物种身份是当前和未来情况下死亡率的最重要预测指标。我们的研究结果显示，由于杨树胡杨（Populus tremuloides）的高死亡率，中洛矶山脉和南部洛基山脉的近期死亡率相对较高，扭叶松松，松albicaulis和冷杉金莲。在几个物种中观察到较低的死亡率水平，在所有其他部分中观察到的年死亡率<1％。预测大多数物种的未来死亡率将显着增加，并且与物种级别（而非地块级别）的近期死亡率有很好的相关性。这些结果表明，未来的模拟或预测广泛森林死亡的尝试将受益于对脆弱物种的更多研究，并且某些物种的重大死亡事件可能对整个系统的动态变化并不重要。