The effects of drought and disturbance on the growth and developmental instability of loblolly pine (Pinus taeda L.) |
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| Affiliation: | 1. University of Vermont, Rubenstein School of Environment and Natural Resources, 81 Carrigan Drive, Burlington, VT 05405, United States;2. USDA Forest Service, Northern Research Station, 81 Carrigan Drive, Burlington, VT 05405, United States;1. Misión Biológica de Galicia, Consejo Superior de Investigaciones Científicas (MBG-CSIC), Apdo. 28, 36080 Pontevedra, Spain;2. Faculty of Forestry, Institute for Dehesa Research (INDEHESA), University of Extremadura, Avenida Virgen del Pue rto 2, 10600 Plasencia, Spain;3. Unit for Sustainable Forest and Environmental Management, University of Santiago de Compostela, 27002 Lugo, Spain;4. Department of Forest Ecology & Genetics, Forest Research Centre, INIA-CIFOR, Carretera de la Coruña km 7.5, 28040 Madrid, Spain;5. Sustainable Forest Management Research Institute, INIA-University of Valladolid, Avda. Madrid 44, 34004 Palencia, Spain;6. iuFOR-EiFAB, Universidad de Valladolid, Campus Duques de Soria, 42004 Soria, Spain;7. Laboratorio de Dendrocronología y Cambio Global, Facultad de Ciencias Forestales y Recursos Naturales, Universidad Austral de Chile, Valdivia, Chile;1. Institute of Desertification Studies, Chinese Academy of Forestry, Beijing 100091, China;2. Institute of Ecological Conservation and Restoration, Chinese Academy of Forestry, Beijing 100093, China;3. School of Forestry and Wildlife Science, Auburn University, AL 36830, United States;4. Institute of Ecological Restoration, Kongju National University, Chungcheongnam-do 32439, Republic of Korea |
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| Abstract: | Ecological indicators provide early warning of adverse environmental change, helping land managers adaptively manage their resources while minimizing costly remediation. In 1999 and 2000, we studied two such indicators, growth and developmental instability, of loblolly pine (Pinus taeda L.) influenced by mechanized infantry training at Fort Benning, Georgia. Disturbed areas were used for military training; tracked and wheeled vehicles damaged vegetation and soils. Highly disturbed sites had fewer trees, diminished ground cover, warmer soils in the summer, and more compacted soils with a shallower A-horizon. We hypothesized that disturbance would decrease the growth of needles, branches, and tree rings, increase the complexity of tree rings, and increase the developmental instability of needles. Contrary to our expectations, however, disturbance enhanced growth in the first year of the study, possibly by reducing competition. In the second year, a drought reduced growth of branches and needles, eliminating the stimulatory effect of disturbance. Growth-ring widths increased with growing-season precipitation, and decreased with growing-season temperature over the last 40 years. Disturbance had no effect on tree-ring complexity, as measured by the Hurst exponent. Within-fascicle variation of current-year needle length, a measure of developmental instability, differed among the study populations, but appeared unrelated to mechanical disturbance or drought. |
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