Overstory-understory biomass changes over a 35-year period in southcentral Oregon

Forest canopy development is known to influence understory biomass relationships. An 85,268 ha area in southcentral Oregon was examined for changes in overstory canopy closure using 1953 and 1988 aerial and satellite imagery and a geographic information system. A negative exponential curve predicted a loss of approximately half of understory biomass over the 35-year interval. Reductions in understory biomass were most pronounced at higher elevations where growing conditions for conifers and canopy closure changes were most pronounced. The loss of understory biomass was related to declines in mule deer (Odocoileus hemionus) populations in the area. (C) 2001 Elsevier Science B.V. All rights reserved.