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LONG-TERM TRENDS IN GROWTH OF PINUS PALUSTRIS AND PINUS ELLIOTTII GROWING ALONG A HYDROLOGICAL GRADIENT IN CENTRAL FLORIDA
Foster, T. E. AND J R. Brooks. LONG-TERM TRENDS IN GROWTH OF PINUS PALUSTRIS AND PINUS ELLIOTTII GROWING ALONG A HYDROLOGICAL GRADIENT IN CENTRAL FLORIDA. CANADIAN JOURNAL OF FOREST RESEARCH. NRC Research Press, Ottawa, Canada, 31:1661-1670, (2001).
Land-use change and urbanization has led to changes in the hydrologic regime in wet central Florida, with a trend toward lowered water table levels. These hydrologic changes are having environmental consequences in wetlands, where shifts in species composition and fire frequency accompany the drier conditions. Decreases in water table levels may also be impacting ecologically important upland systems, such as pine flatwoods and sandhills. In this study, we determine how the growth of response of Pinus pelliottii var. elliottii Engelm. (Slash pine) and Pinus palustris Mill. (Longleaf pine) to climate varies along a hydrologic gradient from mesic flatwoods to xeric sandhills. Pinus elliottii individuals responded negatively to high water availability on sites with shallow water table (<1m) but responded positively on sites with a deeper water table with individuals having a 41% lower basal area increment (BAI) on the drier site. In contrast the growth response of P. palustris, which only grows in the dryer sites, was similar along the hydrologic gradient, with growth being positively related to water availability and only a 16% lower BAI on the driest site. Reductions in growth and increases in fire frequency caused by drier conditions suggest that lowered water table levels at this site would favor P. palustris.