Browsing by Author "Fields-Johnson, Christopher Warren"
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- Appalachian Surface Mine Reforestation Techniques: Effects of Grading, Cultural Treatments and Species SelectionFields-Johnson, Christopher Warren (Virginia Tech, 2011-01-21)Surface mining for coal in the Appalachian region has removed over 0.6 million Ha of mixed mesophytic forest. Successful reforestation would be beneficial, but questions remain concerning application of reclamation and reforestation methods on operational scales. Four experiments were performed testing these methods on newly reclaimed and previously reclaimed, but unused, former mines. On newly reclaimed sites, loose grading during reclamation reduced erosion and increased plant community diversity compared to smooth grading. Seeding only annual ryegrass (Lolium multiflorum) for erosion control, along with tree planting, increased plant community diversity and improved survival and growth of hybrid American chestnut (Castanea dentata x Castanea mollissima), compared to conventional seeding. Surface water infiltration was positively correlated with herbaceous ground cover. On older mines, subsoil ripping to alleviate compaction improved tree survival and growth, in some cases, after five growing seasons. Of the three species groups planted, including Eastern white pine (Pinus strobus), mixed native hardwoods had the best survival and hybrid poplar (Populus deltoides x Populus trichocarpa) produced the most biomass. Hybrid American chestnuts survived and grew better when planted as bare-root seedlings than when planted as ungerminated nuts in tree tubes, demonstrating the potential for planting bare-root chestnut seedlings along with other species when reforesting reclaimed surface mines. This can aid in restoring American chestnut, functionally extinct since the blight (Cryphonectria parasitica), to its former range. These cultural practices can be employed to accelerate reforestation of mined lands, but many questions remain about their capability to fully restore ecosystem structure and processes.
- Biochar in Land Reclamation, Biosolids Applications and Prescribed FiresFields-Johnson, Christopher Warren (Virginia Tech, 2016-12-01)Biochar is a form of stable organic carbon whose application to soils has the potential to sequester large amounts of atmospheric CO2 while improving the physical, chemical and biological properties of soil. However, the optimal rates and methods of biochar application are unknown for many situations. Three experiments were performed to test methods of biochar application to soils as a stand-alone amendment, in combination with biosolids as a complementary amendment and in-situ through controlled landscape burning. The first was a greenhouse pot study, which involved combining biochar with spoil from an Appalachian surface coal mine to grow trees. Biochar combined with mine soil produced a much higher growth rate for trees, and pure biochar helped tree root growth, suggesting that it might be useful as a broadcasted amendment, as a nursery growing medium or as a backfill in tree planting holes. The second experiment explored methods to combine biochar and biosolids materials to form a granular product. Combining biochar and biosolids before applications reduced windborne losses of biochar as well as the nutrient leachate produced by the biosolids. Drum rolling was found to work best for producing aggregate granules. Wetting pure biochar to 100% gravimetric water content before applications reduced windborne losses from over 50% to under 5% as compared to when it was applied as a dry product. A series of controlled burns were conducted in the third experiment to determine the ideal range of meteorological conditions to produce the highest possible biochar yields in-situ. Relative humidity, forest litter moisture and ambient temperature were found to be the governing factors over the tonnage of biochar produced. Up to 3.0 Mg Ha-1 of biochar were produced under ideal conditions by controlled burning. Repeated high-yielding burns have the potential accumulate large amounts of biochar in the soil to improve soil properties.