© 2004 Heron Publishing—Victoria, Canada
Enhancement of understory productivity by asynchronous phenology with overstory competitors in a temperate deciduous forest
William M. Jolly (1, 2), Ramakrishna Nemani (1) and Steven W. Running (1)
1. NTSG, College of Forestry and Conservation, SC428, University of Montana, Missoula, MT 59812, USA / 2. Corresponding author (mattj@ntsg.umt.edu) / Received August 6, 2003; accepted January 10, 2004; published online July 1, 2004
Summary
Some saplings and shrubs growing in the understory of temperate deciduous forests extend their periods of leaf display beyond
that of the overstory, resulting in periods when understory radiation, and hence productivity, are not limited by the overstory
canopy. To assess the importance of the duration of leaf display on the productivity of understory and overstory trees of
deciduous forests in the north eastern United States, we applied the simulation model, BIOME-BGC with climate data for Hubbard
Brook Experimental Forest, New Hampshire, USA and mean ecophysiological data for species of deciduous, temperate forests.
Extension of the overstory leaf display period increased overstory leaf area index (LAI) by only 3 to 4% and productivity
by only 2 to 4%. In contrast, extending the growing season of the understory relative to the overstory by one week in both
spring and fall, increased understory LAI by 35% and productivity by 32%. A 2-week extension of the growing period in both
spring and fall increased understory LAI by 53% and productivity by 55%.
Keywords:
BIOME-BGC, fPAR, LAI, NPP, phenology, understory.
