Importance / Issues

Aspen stands provide an important source of understory plant diversity in the conifer dominated forests of Lassen Volcanic National Park (LAVO) and may be considered a keystone species.  However, studies indicate aspen are declining in the region and throughout the West.  Preliminary results from an aspen inventory and assessment of LAVO indicate a similar trend.  Most stands are small in size (median size of currently mapped stands is 0.135 hectare), heavily browsed by deer, and experiencing moderate to high levels of conifer encroachment.  The implication is that as aspen stands decline in area, the under story plant diversity harbored beneath them is lost. 

Few studies have sought to measure loss of plant diversity from aspen stands in decline.  This study will quantify the amount and rate of conifer encroachment in 36 aspen stands at LAVO over the period 1952-2005, and will measure current levels of understory diversity in aspen stands over the local range of conifer encroachment.  It will describe the amount of biodiversity that is at risk of loss, the rate at which it is changing, and evaluate the association between conifer encroachment and understory diversity.  This approach will provide managers with the information needed to stabilize changing aspen communities at LAVO.

Principal Investigators

Dr. Kenneth W. Tate
Department of Plant Science
University of California, Davis

and

Sarah McCullough
Graduate Student
Department of Plant Science
University of California, Davis

Objectives

The first objective is to quantify the amount and overall rate of conifer encroachment from 1952-2005 in aspen stands using remote sensing methods.

The second objective is to examine the association between the degree of conifer encroachment and understory diversity in aspen stands over the full range of encroachment levels.

Parks

Lassen Volcanic National Park

Project Status

The final field season was wrapped up in 2008 and a final report will be completed in 2009.