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.<br>These studies were established to identify best practices in commercial thinning of true fir stands.<br>Summaries of these data can be found in multiple publications which are listed as cross-references below.