Influence of light and moisture on longleaf pine seedling growth in selection silviculture

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Selection silviculture has become increasingly common for longleaf pine management, yet questions remain regarding residual canopy effects on seedling survival and growth. To determine what levels of residual overstory promote adequate seedling recruitment, 600 containerized longleaf pine seedlings were planted on two sites during the 2007-2008 dormant season. To differentiate overstory from understory influences, half of the seedlings were randomly selected for understory removal (with herbicide). Canopy gap fraction was determined using hemispherical photography and average soil moisture was determined from four time domain reflectometer (TDR) measurements during the 2008 and 2009 growing seasons. Seedling groundline diameter (GLD) was measured at planting and in August, 2008 and 2009. First-year results showed weakly positive relationships between soil moisture and seedling growth, whereas generally negative but statistically non-significant relationships existed between gap fraction and seedling growth. Second-year results showed few significant relationships, but generally positive trends between gap fraction and GLD growth. No general trend was present between soil moisture and GLD growth. Data collected during this study support previous research suggesting that initial longleaf pine survival and growth are limited by moisture availability, but following establishment, light becomes the primary driver of longleaf pine seedling growth.

  • Citation: Dyson, David S.; Loewenstein, Edward F.; Jack, Steven B.; Brockway, Dale G. 2012. Influence of light and moisture on longleaf pine seedling growth in selection silviculture. In: Butnor, John R., ed. 2012. Proceedings of the 16th biennial southern silvicultural research conference. e-Gen. Tech. Rep. SRS-156. Asheville, NC: U.S. Department of Agriculture Forest Service, Southern Research Station. 109-116.

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