Semester

Spring

Date of Graduation

2010

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Forest Resource Management

Committee Chair

Kathryn Piatek

Abstract

Eastern Hemlock Tsuga canadensis is a coniferous tree native to eastern North America. It ranges from northeastern Minnesota eastward through southern Quebec, and from the southern Appalachian Mountains to northern Georgia and Alabama.;This majestic tree is threatened with elimination by an invasive species Hemlock Woolly Adelgid (HWA) Adelges tsugae introduced in the USA in 1924, which is believed to be a native of Asia. HWA reduces shoot growth, provokes branch dieback, and eventually tree death.;One strategy to help mitigate the fast spread of HWA is to determine what may cause host potential resistance to HWA and how to use this information to develop HWA-resistant management program. This project was initiated to....;To do that, randomly selected trees have been studied in Allegheny National Forest in 2006 with monthly data collection by hand-held soil probe instruments measuring temperature and water content noting the time of sampling and also some of them have been instrumented with station recording equipment called Hobo with recorders inserted at 15 cm soil depth and collecting temperature and water content data continuously. Net N mineralization and net nitrification were calculated using the in situ incubation technique, in this method the values of extractable nitrate-N and ammonium-N in incubated soil are compared to the initial. Exchangeable ammonia was extracted from air-dried soil samples that were sieved through a 2 mm sieve, using 2 M KCl in a 10:1 solution:soil ratio.;Statistical analysis was conducted using SAS with data collected, the main effects were thinning treatment (reference, thinning), soil pH, soil organic matter percentage, tree DBH, soil temperature, sampling months.;The thinning (treatment) is statistically significant (p=0.053). The thinned plots mineralize more total nitrogen, almost 10 mg/kg of soil, approximately 50% than the reference plots. Thus, the observed N mineralization rate for the growing season was 21.7 mg/kg to 30 cm soil depth in control plots, or 65.8 kg N/ha. The estimated rate of N mineralization in HWA-infested stands was 30 times the observed rate, reaching 1973 kg/ha.;A series of spatial prediction maps of the landscape Nitrogen levels were created by using ArcGIS 9.2 software that helped acquire a spatial perspective of the soil N mineralization rates in forest ecosystems at a large scale. These spatial prediction maps will become increasingly important once the HWA infests the study site and will be visible impacts of N mineralization rates change in forest soil.;By creating a data base before HWA infestation of the stand and continuing gathering data after HWA infestation, with the help of the nitrogen mineralization model we will be able to elucidate the stand nutrient vs. HWA cause and effect relationship.;Nitrogen forms are an important water quality parameter, but in excess, it can be detrimental to waterways and their ecosystems. Enriched nutrient loads to streams may alter surface water quality and disrupt management of watersheds used by municipal treatment water. Nitrate and cations diffusion into the surface water can reduce its drinking quality. Blue-baby syndrome (Methemoglobinemia) can be caused by high nitrate found in drinking waters.

Download

Share

COinS