title: Influence of Human Pressure on Forest Resources and Productivity at Stand and Tree Scales: The Case Study of Yunnan Pine in SW China.
abstract: This paper examines human impact on stands and individual trees ofPinus yunnanensisgrowing near the small mountain villages of Pianshui and Yangjuan in southwestern Sichuan Province, China. In an effort to assess whether use of these forests was sustainable, we examined the effects of human use in two ways. First, we directly measured the effect of cutting branches, for fuel and fodder, on tree growth. We hypothesized that branch cutting would negatively impact tree growth. We established 12 plots on four hills and compared 14 pairs of trees, one tree in each pair with an apparently full crown and the other with a considerable portion of the crown removed. Second, we assessed stand and tree properties over a 500 m elevation gradient above the villages where we hypothesized that as elevation increases, stand and tree properties should show fewer human impacts. Although extensive branch cutting reduced the live crown, tree height and diameter, compensatory processes likely enabled trees to recover and to add basal area increments (BAIs) similar to those added by trees with full crowns. Trees and stands close to villages showed less growth and lower basal areas, respectively, than stands and trees at intermediate or distant elevations from villages. Areas relatively close to the villages showed considerable effects of human-related disturbances such as branch cutting, grazing, tree and shrub removal, losses of litter, and human and animal trails. Such areas had increased soil erosion and often loss of the 'A' horizon. Stands close to villages had younger trees, lower stand basal areas, smaller basal area increments, and more stumps. Our results suggest an increasingly vulnerable interface between occupants of these two villages and their surrounding forests.
authors.affiliation: School of Environmental and Forest Sciences, University of Washington, Seattle, WA 98195, USA.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Hinckley
authors.affiliation: School of Environmental and Forest Sciences, University of Washington, Seattle, WA 98195, USA.
authors.forename: Phillip
authors.initials: P
authors.lastname: Chi
authors.affiliation: School of Environmental and Forest Sciences, University of Washington, Seattle, WA 98195, USA.
authors.forename: Keala
authors.initials: K
authors.lastname: Hagmann
authors.affiliation: Department of Anthropology and School of Environmental and Forest Sciences, University of Washington, Seattle, WA 98195, USA.
authors.forename: Stevan
authors.initials: S
authors.lastname: Harrell
authors.affiliation: Geology Department, Oberlin College, Oberlin, Ohio 44074, USA.
authors.forename: Amanda Henck
authors.initials: AH
authors.lastname: Schmidt
authors.affiliation: School of Environmental and Forest Sciences, University of Washington, Seattle, WA 98195, USA.
authors.forename: Lauren
authors.initials: L
authors.lastname: Urgenson
authors.affiliation: College of Life Sciences, Sichuan University, Chengdu 610064, China.
authors.forename: Zong-Yong
authors.initials: ZY
authors.lastname: Zeng
keywords: Basal area increment; Pinus yunnanensis; Ring width; Stand basal areas; Tree growth