Shrub, Seedling and Sapling Density at Bonanza Creek LTER Research Sites (2006-Present)

This study is a survey of the density of tall shrubs, saplings, and seedlings at Bonanza Creek LTER Control Plots. Densities have been measured at some sites since 1975 while others began in the mid 1980's. In 2006 methodology was changed in attempt to better capture the spatial variability of shrub and tree species within the research sites. The current method, presented here, uses a 2 meter wide transect along two site boundarys covering 220m2. All seedlings, saplings, and tall shrubs >1m (regardless of species) are counted by species and size class along the transect. The previous method used 4m2 circular plots at 20 points on a 10mx10m grid within the control plot for an area of 80m2. The circular method measured all seedlings, saplings, and a certain set of "tall shrubs" (see metadata for <a href="http://www.lter.uaf.edu/data_detail.cfm?datafile_pkey=175"> Vegetation Plots of the Bonanza Creek LTER Control Plots: Species Count (1975 - 2004) </a> for a definition of "tall shrubs"), regardless of height. The height requirement creates an issue when comparing the old and new methods for early successional stands. For Alnus and Salix this is likely only a problem in the FP0 sites as they are the only sites with a high density of shrubs shorter than 1m. Shrub community changes at these early successional sites should be analyzed using precent cover data. At the later successional sites most Alnus and Salix shrubs are greater than 1m so the transect method likely does not underrepresent density. The raw data from the circular method can be found in <a href="http://www.lter.uaf.edu/data_detail.cfm?datafile_pkey=175"> Vegetation Plots of the Bonanza Creek LTER Control Plots: Species Count (1975 - 2004) </a>.