Plant succession and biomass dynamics following logging and burning in Watersheds 1 and 3, Andrews Experimental Forest, 1962 to Present

Watersheds 1 and 3 in the HJ Andrews Experimental Forest have a long history of hydrologic, geomorphic, and ecological study. Long-term successional studies in the two watersheds are unprecedented in their scope and duration (1962 to present), spanning more than 50 years of post-logging measurements. To date, studies have focused on understory responses to logging and burning, early stand developmental processes (tree growth and mortality), and understory responses to canopy closure. Understory sampling was initiated in 1962, prior to harvest, and includes approximately 190, 2 x 2 m permanent understory plots. Measurements include estimates of ground-surface conditions and abundance (cover and biomass) of herbaceous, shrub, and tree species. Plots were sampled annually through 1972/1973, but less frequently thereafter (every 2-6 years). Studies of early stand development were initiated in 1979/1980 in conjunction with the understory plots. In each of approximately 190, 250 m2 tree plots all conifer and hardwood stems greater or equal to 1.4 m tall are tagged, measured for diameter, and assessed for status (live or dead, including the cause of mortality). Both watersheds have experienced recent snow-related windthrow (2019, 2020) and parts of WS1 have burned in a low-severity wildfire (2020) adding complexity to early successional outcomes.