Forests 2016, 7(10), 214; https://doi.org/10.3390/f7100214
Loblolly Pine Productivity and Water Relations in Response to Throughfall Reduction and Fertilizer Application on a Poorly Drained Site in Northern Florida
Maxwell G. Wightman 1,2,*
, Timothy A. Martin 1
, Carlos A. Gonzalez-Benecke 2, Eric J. Jokela 1, Wendell P. Cropper, Jr. 1 and Eric J. Ward 3,4
, Carlos A. Gonzalez-Benecke 2, Eric J. Jokela 1, Wendell P. Cropper, Jr. 1 and Eric J. Ward 3,4
1
School of Forest Resources and Conservation, University of Florida, Gainesville, FL 32611, USA
2
Department of Forest Engineering, Resources, and Management, Oregon State University, Corvallis, OR 97331, USA
3
Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
4
Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC 27606, USA
*
Author to whom correspondence should be addressed.
Academic Editor: Chris A. Maier
Received: 21 July 2016 / Revised: 2 September 2016 / Accepted: 15 September 2016 / Published: 26 September 2016
Abstract
Loblolly pine (Pinus taeda L.) forests are of great ecological and economic value in the southeastern United States, where nutrient availability frequently limits productivity. The impact of fertilizer application on the growth and water relations of loblolly pine has been investigated by numerous studies; however, few field experiments have examined the effects of drought. Drought is of particular interest due to the potential for climate change to alter soil water availability. In this study, we investigated the impact of fertilizer application and a 30% reduction in throughfall on loblolly pine productivity, transpiration, hydraulic conductance, and stomatal conductance. The study was installed in a ten-year-old loblolly pine plantation on a somewhat poorly drained site in northern Florida. Throughfall reduction did not impact tree productivity or water relations of the trees. This lack of response was attributed to abundant rainfall and the ability of trees to access the shallow water table at this site. Fertilizer application increased basal area production by 20% and maximum leaf area index by 0.5 m2∙m−2, but it did not affect whole-tree hydraulic conductance or the sensitivity of stomatal conductance to vapor pressure deficit. During the spring, when leaf area and vapor pressure deficit were high, the fertilizer-only treatment increased monthly transpiration by 17% when compared to the control. This relationship, however, was not significant during the rest of the year. View Full-TextKeywords:
Pinus taeda; throughfall exclusion; nutrient amelioration; transpiration; stomatal conductance; sap flow
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Wightman, M.G.; Martin, T.A.; Gonzalez-Benecke, C.A.; Jokela, E.J.; Cropper, W.P., Jr.; Ward, E.J. Loblolly Pine Productivity and Water Relations in Response to Throughfall Reduction and Fertilizer Application on a Poorly Drained Site in Northern Florida. Forests 2016, 7, 214.
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