Tree stand structure summary at Bonanza Creek Experimental Forest LTER sites

We measure trees and shrubs within 50 x 60 m permanent plots at LTER research sites within the Bonanza Creek Experimental Forest, as a means to monitor vegetation change and to estimate productivity. The 27 LTER research sites represent three replicates each of six successional stages of primary succession on the floodplain of the Tanana River and three stages of succession following wildfire in the uplands. All trees and tall shrubs within the plot are stem mapped, and the dbh is measured at least every 5 years. The condition of each tree is assessed at the time of measurement and following major disturbance events. Band dendrometers have been placed on select trees at each site where applicable. Litterfall and seedfall are collected and measured annually. White spruce seedlings are mapped and their heights measured every 2 years within the tree plots at younger successional stages. The DBH of alders and willows are measured. Shrub heights are measured annually at young floodplain stands. Changes in species composition through succession are a function of life history traits modified by facilitative and competitive interactions. Vegetation-caused changes in resource (light, nutrients, and moisture)availability during succession control vegetation biomass, productivity, and organic matter and nutrient distribution.