Reapplication of Silvicultural Treatments Impacts Phenology and Photosynthetic Gas Exchange of Loblolly Pine

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A loblolly pine (Pinus taeda L.) plantation, established in 1981, was thinned and fertilized in 1988. Thinning and fertilization treatments were applied again in early 1995. The morphology of current flushes and needles were measured between March and October in 1995 through 1997. Physiological responses were monitored in the upper and lower crowns. Needle-fall was collected biweekly, and annual needle biomass was estimated. Although refertilization had little impact on needle-level physiology, it shifted bud burst 1 week earlier and significantly enhanced flush and needle growth. The fertilized trees produced more leaf area per shoot than the unfertilized trees. Refertilization increased tree-level and plot-level annual needle-fall biomass production. Rethinning increased leaf area per fascicle and annual needle-fall biomass per tree. As light level and crown exposure were increased after rethinning, rates of photosynthesis and transpiration of lower crown foliage on the thinned plots rose considerably, but daytime needle water potential remained unaffected.

  • Citation: Tang, Zhenmin; Chambers, Jim L.; Sword, Mary A.; Yu, Shufang; Barnett, James P. 2004. Reapplication of Silvicultural Treatments Impacts Phenology and Photosynthetic Gas Exchange of Loblolly Pine. Gen. Tech. Rep. SRS–71. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. pp. 450-457

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