Food Reserves in Mountain Longleaf Pine Roots during Shoot Elongation

Survival and growth of longleaf pine seedlings depends upon a well-developed root system. Soil moisture is also critical for the seedling to emerge from the grass-stage. When longleaf pine seedlings emerge from the grass stage, they grow rapidly in height and diameter. Branches are often few in number and, if present, may have low photosynthesis rates. This growth pattern is seen on all longleaf pine sites, including low fertility mountain soils. Root growth patterns on poor soils suggest that biochemical adaptations are occurring when compared to those of Coastal Plain soils. Our results show that roots of mountain longleaf pine have a normal anatomy but also have unusual amounts of starch when compared to loblolly pine roots growing during phenologically equivalent time periods. Longleaf pine roots from mountain soils appeared large in diameter and appeared to grow much nearer the soil surface than roots we observed from Coastal Plain longleaf pine. Among the variables examined to determine root food reserves, numbers of starch grains were found to be easiest to quantify. Starch grains were large in size and uniformly filled root cells. Nuclear staining served to verify the observed root cells were healthy. These results yield methodology potentially useful in assessment of health and productivity of longleaf pine. 1Emeritus Forest Service, Plant Pathologist, Institute of Tree-Root Biology, USDA Forest Service, 320 Green Street, Athens, GA 30602, respectively. Figure 1—Location of longleaf pine saplings used in this study. and extensively to support height growth rates of 1.0 to 2.0 meters per year. The stand of several thousand sapling longleaf pine was approximately 3.5 m in height. The randomly sampled trees ranged from 6.0 to 8.0 cm d.b.h. (diameter at breast height). Buds had not expanded at the time of sampling. Roots were also sampled from randomly selected adult longleaf pine in northwestern South Carolina (Savannah River Site, New Ellenton SC). Trees sampled at this Citation for proceedings: Outcalt, Kenneth W., ed. 2002. Proceedings of the eleventh biennial southern silvicultural research conference. Gen. Tech. Rep. SRS–48. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 622 p.