Effect of Thinning and Slash Burning on Nitrogen and Carbon in Ecosystems of Young Dense Ponderosa Pine

Author: Klemmedson, J. O.

Source: Forest Science, Volume 22, Number 1, 1 March 1976 , pp. 45-53(9)

Publisher: Society of American Foresters

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Abstract:

Biomass, N, and C removed in thinning two young dense stands of ponderosa pine in Arizona was estimated by sampling loose and piled slash, and pulpwood on 1/3 hectare areas. Quantities of N and C in thinnings were compared with amounts in the unthinned forest ecosystem. The effect of slash burning on N and C was evaluated by sampling the residual slash and burned residue for 2 years after the slash fires. Nearly 21,000 kg/ha, or from 8.5 to 12.4 percent, of ecosystem C and from 75 to 101 kg/ha, or 1.2 to 1.6 percent, of ecosystem N were removed from the standing crop by thinning. Loss of N in pulpwood was only 0.2 percent. Losses of N from combined thinning and burning operations ranged from 59 to 91 kg/ha and exceeded amounts of N in piled slash because of heavy losses of N from forest floor under piled slash. Losses of C and N from burning averaged 79 and 87 percent, respectively. Loss of N, although low on the basis of ecosystem N, may be important in view of low rates of N fixation and the relative size and stability of resistant fractions of soil humus. Loss of nutrients could have been reduced by attention to moisture content of the forest floor and method of piling slash. Forest Sci. 22:45-53.

Keywords: Sapling-pole stands; biomass; forest floor; litter; Pinus ponderosa

Document Type: Journal article

Affiliations: 1: Professor, School of Renewable Natural Resources, University of Arizona, Tucson, Arizona 85721

Publication date: 1976-03-01

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