Municipal wastewater effects on nitrogen cycling in a mature hardwood forest

dc.contributor.authorKim, Dong Yeoben
dc.contributor.committeechairBurger, James A.en
dc.contributor.committeememberJohnson, James E.en
dc.contributor.committeememberReneau, Raymond B. Jr.en
dc.contributor.committeememberSeiler, John R.en
dc.contributor.committeememberZelazny, Lucian W.en
dc.contributor.departmentForestryen
dc.date.accessioned2014-03-14T21:21:56Zen
dc.date.adate2005-10-21en
dc.date.available2014-03-14T21:21:56Zen
dc.date.issued1992-03-26en
dc.date.rdate2005-10-21en
dc.date.sdate2005-10-21en
dc.description.abstractLand disposal of municipal wastewater is considered ecologically acceptable and cost effective. The success of land treatment systems, however, requires proper functioning of all ecosystem components. The impact of municipal wastewater irrigation on the structure and function of an Appalachian hardwood forest in Virginia was investigated. Four irrigation rates (17.5, 35, 70, and 140 em yr⁻¹ ) were applied in this hardwood forest, and their effects on forest nutrient cycling were monitored for two years. Tree growth, seedling reproduction, tree mortality, species diversity, and N sequestering by vegetation were not changed significantly. Herbaceous ground cover increased due to irrigation, except for the 140 cm yr⁻¹ treatment where the heavy spray caused physical damage to the cover. Depending on the rate applied, the mature hardwood forest system sequestered only -3.4 to 8.2 kg N ha yr⁻¹ in the above ground biomass. Therefore, the fate of added N to the system became a function of N transformation processes in the soil. Nitrogen mineralization and nitrification increased as irrigation increased. Denitrification rates were not affected by irrigation; the process of denitrification did not constitute a significant N output from the forest system. The additional soil nitrate (N0₃) was left to leach because of the low assimilation by the plant/soil system and the low denitrification rate. Nitrogen storage decreased in the forest floor due to the increase in litter decomposition, and increased in the surface soil due to the increase in microbial N assimilation. Total soil N increased on the low irrigation sites and decreased on the high irrigation sites, indicating that high rates of irrigation stimulated N loss from the soil by enhancing soil N transformations. The health of the forest ecosystem was not adversely affected during this period, but the forest did not serve as a net sink for N. There was little opportunity for N sequestering in this mature hardwood forest. Without harvesting and regeneration, the system is likely to lose system N when wastewater is applied. When wastewater is applied to lands, N sequestering and denitrification should be maximized in order to minimize the pollution potential of N0₃ leaching to groundwater systems.en
dc.description.degreePh. D.en
dc.format.extentxi, 128 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-10212005-123011en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-10212005-123011/en
dc.identifier.urihttp://hdl.handle.net/10919/40072en
dc.language.isoenen
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V856_1992.K5585.pdfen
dc.relation.isformatofOCLC# 26354082en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.lccLD5655.V856 1992.K5585en
dc.subject.lcshHardwoodsen
dc.subject.lcshNitrogen cycleen
dc.subject.lcshSewageen
dc.titleMunicipal wastewater effects on nitrogen cycling in a mature hardwood foresten
dc.typeDissertationen
dc.type.dcmitypeTexten
thesis.degree.disciplineForestryen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en
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