California statewide wildfire burn regime projections (2020-2100)

At the intersection of climate change and rural development, wildfire has emerged as a threat to agriculture in the western United States. This nexus is particularly problematic for the rapidly developing cannabis industry in California, which includes farms located outside of traditional agricultural zones and within landscapes potentially more prone to wildfire. With the goal of determining whether cannabis is uniquely vulnerable to direct wildfire impacts (in terms of crop loss to burning), we integrated fire hazard severity zone data, wildfire perimeters, and future burn regime projections in relation to the location and cultivated area of cannabis farming. We then applied descriptive statistics and generalized additive models (GAM) to compare the location of licensed cannabis farms to other agricultural types in California, including grapes, pasture, and all other general crops combined. We found cannabis farming was located more often in high and very high fire hazard severity zones and closer to wildfire perimeters than any other agricultural type. GAM estimates of likelihood of occurrence in high and very high severity zones were highest for cannabis, even after accounting for spatial clustering of farm types, although there was no reliable difference in predicted distances to wildfire. Cannabis more often occurred in projected (from 2020-2100) wildfire hotspots than all other agricultural types, with GAM estimates affirming a reliably higher likelihood of cannabis in future hotspots than pasture or general crops. Our findings highlight cannabis' particular vulnerability to wildfire in California, and may in fact underestimate wildfire risks given the potential indirect impacts of smoke to crops and farmworkers, which were not evaluated in this study. In light of the sector's growing economic importance in the state, these vulnerabilities should be considered in future cannabis and rural development policies.在气候变化与乡村发展的交叉领域，野火（wildfire）已成为美国西部农业面临的重大威胁。这一关联对加利福尼亚州快速发展的大麻（Cannabis）产业尤为不利：该产业的种植场不仅分布于传统农业区之外，还坐落于野火风险潜在更高的区域。本研究旨在明确大麻种植是否在直接野火影响（即焚烧导致的作物损失层面）上具有独特的脆弱性，为此我们整合了火灾风险严重性分区（fire hazard severity zone）数据、野火过火边界（wildfire perimeters）数据，以及与大麻种植场位置和种植面积相关的未来火况制度（burn regime）预测数据。随后我们采用描述性统计方法与广义加性模型（Generalized Additive Models, GAM），将加利福尼亚州持证大麻种植场的分布与其他农业类型进行对比，涵盖葡萄种植场、牧场及其他所有常规农作物种植场的总和。研究结果显示，相较于其他所有农业类型，大麻种植场更常分布于高、极高火灾风险严重性分区内，且距离野火过火边界更近。即便在控制了种植场类型的空间集聚效应后，基于GAM估算的大麻在高、极高风险分区内的出现概率仍为所有农业类型中最高；不过在预测的野火距离上，各类农业类型之间并无显著可靠差异。在2020至2100年的野火热点预测区域中，大麻种植场的分布占比同样高于其他所有农业类型；GAM估算结果证实，相较于牧场或常规农作物，大麻在未来野火热点区域内的出现概率显著更高。本研究结果凸显了加利福尼亚州大麻产业对野火的特有脆弱性；而考虑到烟雾对作物及农场工人的潜在间接影响（本研究未对此进行评估），实际野火风险可能较本研究估算值更高。鉴于该产业在加利福尼亚州的经济重要性日益提升，未来的大麻产业与乡村发展政策应纳入上述脆弱性考量因素。