PARENT SESSION
Oral Session 81: Forest Ecology IV: Seeds, Growth, and Recruitment.
Presiding: J Kush
Wednesday, August 4, 1:30 PM to 5:00 PM, Meeting Room C 120.
Stand thinning affects foliar physiology in balsam fir and red spruce trees.
Minocha, Rakesh*,1, Long, Stephanie1, Wagner, Robert2, 1 USDA Forest Service, Durham, NH, USA2 University of Maine, Orono, ME, USA
ABSTRACT- It is important to assess early changes in foliar physiology caused by forest management practices such as thinning that may be linked to either increases or decreases in forest productivity. We are quantifying the possible effects of various commercial thinning treatments on the foliar chemistry of spruce and fir trees in northern Maine. Study plots were commercially thinned in 2000 and 2001 as part of a long-term study. One site had previously received pre-commercially thinned (PCT) and was 42 years old. Commercial thinning treatments in this stand included a factorial combination of timing of first entry (0, 5 or 10 yrs) and level of relative density reduction (33% or 50%). The other site had never received PCT and was 58 years old. For low cut lower dbh (diameter at breast height) trees were cut; for dominant cut dominant crop trees with largest dbh were cut; and for crown cut the dominant crop selected trees with largest dbh were kept and any competitors that fall within area of 1/3 of the height of the nearest selected tree were removed while retaining the small dbh trees except those that had to be removed to make room for the heavy machinery. In July 2003, red spruce and balsam fir foliar samples were collected at the two sites from up to 25-canopy trees/species/treatment. Data pooled by density reduction or by thinning method indicated that thinning significantly increased cellular levels of inorganic phosphorus, amino acids, and polyamines for both spruce and fir. The increases were generally greater for the more intensive thinning treatments. Within 3-4 years, it may be possible to determine the relationship between physiological parameters and overall changes in tree and stand growth associated with the thinning treatments. In the future, this information may be used to guide the selection of proper management practices.
Key words: physiology, amino acids, polyamines, phosphorus, red spruce, balsam fir, stand thinning, forest management