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How do short rotations and intensive management affect plant communities in pine plantations?
Jeffries, Stephanie*,1, Wentworth, Thomas1, Allen, H. Lee1, 1 North Carolina State University, Raleigh, North Carolina
ABSTRACT- Over the last several decades, researchers have expressed concern over the long-term sustainability of managed forests in the southeastern United States. Considerable interest has focused on the effects of high-intensity silvicultural practices and short rotations on biodiversity. We conducted a comparative study of second and third rotation plant communities in loblolly pine plantations in the Piedmont of North Carolina. Following harvest of the second rotation forest, a 2x2 factorial experiment was established using two site preparation (chop versus shear, pile, and disk) and two cultural (herbicide versus no herbicide) treatments. Presence/absence data for vascular plant taxa were recorded prior to harvest in year 22 for the second rotation and again at year 18 in the third rotation and analyzed using non-metric multidimensional scaling, cluster analysis, MRPP, and indicator species analysis. Results indicate a significant difference in species composition from the second to third rotation, with disturbance-responsive species associated with the more intensively managed third-rotation stands. The addition of these species to the more intensively managed stands largely accounts for an increase in species diversity from the second to the third rotation. The least intensively managed third-rotation stands (chop, no herbicide) associate more closely with the unmanaged stands of the second rotation. In addition, despite intensive treatments used in the third rotation, differences in species composition due to soil differences across the study site can still be seen. We can infer from these results that high intensity silvicultural practices, such as site preparation and use of herbicides, reduce initial competition and thus permit the persistence of early successional species later in the life of the stand, increasing overall diversity.
KEY WORDS: succession, sustainability, ordination, managed forests