RIPPING COMPACTED MINE SOILS IMPROVED TREE GROWTH 18 YEARS AFTER PLANTING

摘要

Since the implementation of SMCRA, mined land has been heavily graded and much of it has been severely compacted as coal operators attempted to return it to its approximate original contour. Tree survival and growth on compacted mine soils was invariably poor, which compelled mine operators to use non-forestry, post-mining, land reclamation. However, some landowners were interested in post-mining forests for products and services such as carbon sequestration and watershed control. The purpose of our study was to test the effects of ripping mine land after it had been graded and reclaimed using practices common since the implementation of SMCRA in 1978. In 1991, cooperating with a coal operator in Martin County, KY, we created three replications of two site preparation treatments in half-acre plots on level (<5%) and sloping land (40%). The treatments were 1) three grading passes plus tracking (Compacted), and 2) Compacted plus ripping (Ripped). In each of the six plots, three rows of sycamore (Platanus occidentialis), sweetgum Liquidambar styraciflua), yellow poplar (Liriodendron tulipifera), loblolly pine (Pinus taeda), and white pine {Pinus strobus) seedlings were planted on a 3-m spacing (trees were planted in rips). Tree survival, height, and diameter were measured in the fall of 2009. Average tree survival was 47% and 58% for the compacted and ripped treatments, respectively. Overall tree volume, which is an index of above-ground biomass, was 0.37 and 0.50 m3 on the standard and ripped treatments, respectively. Ripping significantly improved the growth of all species except white pine, but only 12% of the white pines survived in either treatment. Ripping proved to be an overall beneficial practice;;however, it did not fully mitigate the adverse effects of compaction. Tree growth potential on these ripped treatment plots was less than half that of pre-mining capability based on average productivity values listed in the county soil survey for the pre-mining soil type.