Long-term effect of density management on growth and yield of true fir (Abies concolor and Abies magnifica) stands in northern California

This data publication includes data from several long-term true fir (white fir (Abies concolor) and red fir (Abies magnifica)) studies established independently across northern California that underwent varying levels of thinning at each site. While some additional treatments such as fertilization were applied to some of the study sites, the primary focus was the effects of residual density following commercial thinning. The study sites include: Jennie Springs, Swain Mountain, and Swain Pole at Swain Mountain Experimental Forest within Lassen National Forest; Big Lake and Crater Peak at Lassen National Forest; Little Glass Mountain and Pumice Stone Mountain at Klamath National Forest; and LaTour site in LaTour Demonstration State Forest (California Department of Forestry and Fire Protection). Data collection years vary for each site, ranging from 1963 to 2023. Tree-level measurements at each site and plot include data such as: species, stand age, diameter at breast height, height, height to base of live crown, and tree condition. Two sites burned in the 2021 Dixie fire also include post-fire data collected in 2022 which include survival status, percentage crown volume affected and torched, crown scorch height and bark char height.
These studies were established to identify best practices in commercial thinning of true fir stands.
Summaries of these data can be found in multiple publications which are listed as cross-references below.

本数据集出版物收录了加州北部独立开展的多项长期真冷杉林研究数据，涉及的树种为白冷杉（Abies concolor）与红冷杉（Abies magnifica），各试验站点均实施了不同强度的疏伐处理。部分试验站点额外施加了施肥等干预措施，但研究核心聚焦于商品性疏伐后的林分保留密度效应。本次研究涵盖的试验站点包括：拉森国家森林内斯温山试验林场的珍妮斯普林斯、斯温山及斯温波尔样点；拉森国家森林内的大湖与火山峰样点；克拉马斯国家森林内的小玻璃山与浮石山样点；以及拉图尔示范州立森林（加州森林与消防部管辖）内的拉图尔样点。各站点的数据收集年份存在差异，跨度为1963年至2023年。各站点及样地的单木测量数据包含如下指标：树种、林分年龄、胸径、树高、活冠基部高度及树木健康状况。其中2个试验站点在2021年迪克西山火灾中受波及，研究团队采集了其2022年的灾后数据，内容涵盖树木存活状态、冠部受损体积占比与过火比例、冠部灼伤高度及树皮炭化高度。本系列研究旨在明确真冷杉林商品性疏伐的最优实践方案。上述数据的汇总成果可参见下文列出的多篇交叉引用出版物。