SIMULATED MINE LAND RECLAMATION IMPACT ON BIOMASS PARTITIONING AND NUTRIENT CONTENTS IN LOBLOLLY PINE

Forest productivity on reclaimed mine land is hindered by soil compaction. Different techniques have been used to alleviate the effect of compaction to various degrees of success. The Forestry Reclamation Approach (FRA) was developed in the Appalachians and has been used to improve forest productivity on reclaimed mines in this region. The FRA provides a step by step method designed to reduce compaction, control erosion, provide land stabilization and accelerate forest succession. This method had not been evaluated in the Gulf Coastal Plain, where the pan scraper reclamation method is commonly used. However, using pan scrapers increases mine soil compaction which reduces productivity. This study was carried out on an experimental site in Houston County, Texas managed by the Arthur Temple College of Forestry and Agriculture at Stephen F. Austin State University. The experiment was established as a randomized complete block design containing three treatments: pan scraper reclamation method traditionally used in this region, an FRA low compaction treatment, and an undisturbed control. Loblolly pine (Pinus taeda L.) seedlings of Texas provenance were hand-planted on each treatment. Loblolly pine seedlings were measured, harvested and analyzed to determine dry biomass and nutrient (N, P, K, Ca, Mg) contents for the three treatments. Allometric equations relating dry weights of foliage, stem, branches and roots to diameter at groundline and height were developed to estimate tree biomass. Estimated biomass accumulation improved with FRA treatment which produced a mean of 759 g foliage, 344 g branch, 440 g stem, 273 g root, 1579 g aboveground, and 1865 g total tree mass. On the pan scraper treatment, estimated biomass was: 159 g foliage, 67 g branch, 90 g stem, 77 g root, 334 g aboveground, 420 g total tree mass. On the control treatment, estimated mean biomass was: 244 g foliage, 111 g branch, 154 g stem, 102 g root, 537 g aboveground, 648 g total tree mass. All treatments allocated more biomass to foliage, however, biomass allocation to roots was relatively higher in the pan scraper treatment than FRA treatment. Nutrient accumulation in tree biomass was highest in FRA treatment and it followed the pattern of biomass accumulation. The nutrient concentrations in different tree tissues decreased in the order foliage \u3e stem \u3e root, except for N and Mg in the pan scraper treatment. Foliage concentrations for all treatments were either at or exceeded the adapted critical concentrations except for N which was slightly lower. However, N was generally the most abundant nutrient in all treatments and was highest in foliage biomass. In summary, these results show that FRA can be an effective reclamation method to improve seedling growth and biomass production in the Gulf Coastal Plain