Year of Publication

2012

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Agriculture

Department

Soil Science

First Advisor

Dr. Christopher Barton

Abstract

Headwater stream systems are important components of the overall hydrologic system. Forestry best management practices (BMP) are effective at minimizing non point source pollution from forest harvesting activities. Streamside management zones (SMZ) are one BMP used to protect surface water quality by maintaining shade near streams, filtering runoff, and minimizing soil disturbance near streams. An evaluation of BMP effectiveness on the watershed scale was conducted at the University of Kentucky’s Robinson Forest. Six watersheds were harvested using a two-age deferment harvest with one of three SMZ configurations applied to each watershed. Two unharvested watersheds served as controls.

Treatment 1 was based on the current Kentucky Forest Practice Guidelines for Water Quality Management and included a 16.8 m SMZ with 50% canopy retention for perennial streams, a 7.6 m SMZ with no canopy retention for intermittent streams, and no SMZ or canopy retention for ephemeral streams with unimproved crossings. Treatment 2 also included a 16.8 m perennial SMZ but increased canopy retention to 100%, as well as a 7.6 m intermittent SMZ with 25% canopy retention, and retention of channel bank trees and use of improved crossings for ephemeral streams. Treatment 3 required a 33.5 m perennial SMZ with 100% canopy retention, a 16.8 intermittent SMZ with 25% canopy retention, and a 7.6 m ephemeral SMZ with retention of channel bank trees and use of improved crossings.

Total suspended solids (TSS) concentration and turbidity was measured in storm samples in perennial and ephemeral streams, and in non-storm samples in perennial and intermittent streams. Nitrate-N, ammonium-N, and dissolved oxygen concentrations were also measured in non-storm samples in perennial and intermittent streams. Temperature and water level were recorded every 15 minutes for the duration of the study.

Results showed that treatment 3 was able to maintain TSS concentrations and turbidity levels similar to those measured in unharvested control watersheds. Increases in nitrate-N and mean daily temperature were measured for all treatments. Ammonium-N and dissolved oxygen concentrations were not different from unharvested control watersheds for any treatment. Storm hydrograph separation did not result in consistent changes post-harvest for any treatment.

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