US Geological Service, Forest and Rangeland Ecosystem Science Center, Boise ID, 83702, USA.
US Geological Service, Forest and Rangeland Ecosystem Science Center, Boise ID, 83702, USA.
J Environ Manage. 2024 Feb 27;353:120154. doi: 10.1016/j.jenvman.2024.120154. Epub 2024 Feb 2.
Fuel-treatments targeting shrubs and fire-prone exotic annual grasses (EAGs) are increasingly used to mitigate increased wildfire risks in arid and semiarid environments, and understanding their response to natural factors is needed for effective landscape management. Using field-data collected over four years from fuel-break treatments in semiarid sagebrush-steppe, we asked 1) how the outcomes of EAG and sagebrush fuel treatments varied with site biophysical properties, climate, and weather, and 2) how predictions of fire behavior using the Fuel Characteristic Classification System fire model related to land-management objectives of maintaining fire behavior expected of low-load, dry-climate grasslands. Generalized linear mixed effect modeling with build-up model selection was used to determine best-fit models, and marginal effects plots to assess responses for each fuel type. EAG cover decreased as antecedent-fall precipitation increased and increased as antecedent-spring temperatures and surface soil clay contents increased. Herbicides targeting EAGs were less effective where pre-treatment EAG cover was >40 % and antecedent spring temperatures were >9.5 °C. Sagebrush cover was inversely related to soil clay content, especially where clay contents were >17 %. Predicted fire behavior exceeded management objectives under 1) average fire weather conditions when EAG or sagebrush cover was >50 % or >26 %, respectively, or 2) extreme fire weather conditions when EAG or sagebrush cover was >10 % or >8 %, respectively. Consideration of the strong effects of natural variability in site properties and antecedent weather can help in justifying, planning and implementing fuel-treatments.
在干旱和半干旱环境中，针对灌木和易燃外来一年生草本植物（EAG）的燃料处理越来越多地被用于减轻野火风险增加的问题，为了进行有效的景观管理，需要了解它们对自然因素的反应。我们利用在半干旱的山艾灌丛草原中进行了四年的燃料隔离带处理收集的实地数据，提出了以下两个问题：1）EAG 和山艾灌丛燃料处理的结果如何随地点的生物物理特性、气候和天气而变化；2）使用燃料特征分类系统火灾模型预测火灾行为如何与保持低负荷、干旱气候草原预期火灾行为的土地管理目标相关。我们使用建立模型选择的广义线性混合效应模型来确定最佳拟合模型，并使用边际效应图来评估每种燃料类型的响应。前期秋季降水增加会导致 EAG 覆盖率降低，而前期春季温度和表层土壤粘粒含量增加会导致 EAG 覆盖率增加。针对 EAG 的除草剂在预处理 EAG 覆盖率>40%和前期春季温度>9.5°C 的情况下效果较差。山艾灌丛覆盖率与土壤粘粒含量呈反比，特别是在粘粒含量>17%的情况下。在以下情况下，预测的火灾行为超过了管理目标：1）当 EAG 或山艾灌丛覆盖率分别>50%或>26%时，平均火灾天气条件；或 2）当 EAG 或山艾灌丛覆盖率分别>10%或>8%时，极端火灾天气条件。考虑到场地属性和前期天气的自然变异性的强烈影响，可以帮助证明、规划和实施燃料处理。
