Clearcutting and pine planting effects on nutrient concentrations and export in two mixed use headwater streams: Upper Coastal Plain, Southeastern USA

Abstract

Timber harvest temporarily increases water yield; however, relationships between hydrologic and nutrient chemistry changes have not been consistent. This study quantified the effects of forest harvesting and site preparation without fertilization and with modern best management practices on nutrient concentrations and yields in small headwater streams of the Southeastern Coastal Plain. We monitored two watershed pairs for 2 years prior to and 1 year following timber harvest and for 2 more years following site preparation and planting. Treatment watersheds were clearcut, and downstream portions of streamside management zones were thinned in Fall 2003. Site preparation (herbicide application and burning) and planting followed a year later. All operations followed 1999 Georgia forestry best management practices. Previously published research revealed a large increase in water yield following harvest. Nutrient concentrations varied significantly within and between monitoring periods, even in reference watersheds. Silvicultural activities had no discernible effect on phosphorus and ammonium concentrations; however, statistically significant increases in nitrate/nitrite (67–340 µg L−1) and total nitrogen concentrations (100–400 µg L−1) in treatment watersheds followed stand re‐establishment. Nutrient yields increased after timber harvest largely as a result of increased water yields, although increased nutrient yields were small relative to inter‐annual and inter‐watershed variability and variability. Annual water yield largely explained the variability in annual nitrogen and phosphorus export from reference and treatment streams (r2 values from 0.65 to 0.98). High NOx concentrations coming from an upstream agricultural area decreased 1600–1800 µg L−1 over several hundred metres in the treatment streams by dilution, uptake or denitrification. Copyright © 2013 John Wiley & Sons, Ltd.

Assessing multi-satellite remote sensing, reanalysis, and land surface models' products in characterizing agricultural drought in East Africa

“…It is likely that lower concentrations of inorganic-N in the more severe organic matter removal treatment are at least in part attributable to higher rates of N-losses. For example, changes in microclimate conditions following harvest such as increases in solar radiation reaching the soil surface, decreases in transpiration and rainfall interception, and increases in the amount of precipitation reaching and infiltrating the forest floor and into the soil would favor higher rates of leaching (Vitousek et al, 1997;Carlyle et al, 1998;Holmes and Zak, 1999;Marchman et al, 2015) and denitrification (Brumme, 1995) following treatment application.…”

Environmental effects of short‐rotation woody crops for bioenergy: What is and isn't known

“…In general, most recent studies conclude that current forestry practices coupled with BMPs have small and short‐term effects on stream water quality (Fraser, Jackson, & Radcliffe, ; Grace, ; Keim & Schoenholtz, ; McBroom, Beasley, Chang, & Ice, ; Witt, Barton, Stringer, Bowker, & Kolka, ; Wynn et al, ). Timber harvesting can increase dissolved nutrient concentrations, particularly nitrate (Aust & Blinn, ; Gravelle, Ice, Link, & Cook, ; Marchman et al, ), due to reduced nutrient uptake by vegetation and increased soil temperatures that accelerate mineralization (Bormann, Likens, Fisher, & Pierce, ; Fox, Buger, & Kreh, ; Kreutzweiser, Hazlett, & Gunn, ). Soil disturbance during harvest can increase sediment concentrations in streams (Grace, ); although most increases in sediment inputs are associated with the construction or use of roads (Anderson & Lockaby, ; Croke & Hairsine, ; Sheridan & Noske, ).…”

Analyses of hydrological and hydrochemical fluxes in selected catchments of the Cerrado and Amazon biomes

“…Although many studies have evaluated the dynamics of carbon and nutrients in streams in several regions of the world (e.g. Southeastern USA (Marchman et al, 2015), subtropical China (Yan et al, 2015), Germany (Strohmeier et al, 2013) and Canada (Jollymore et al, 2012)), studies of carbon export dynamics in low-order tropical catchments are still scarce (de…”