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Title: Water quality effects of short-rotation pine management for bioenergy feedstocks in the southeastern United States

There is growing interest in renewable and domestically produced energy which motivates the evaluation of woody bioenergy feedstock production. In the southeastern U.S., woody feedstock plantations, primarily of loblolly pine (Pinus taeda), would be intensively managed over short rotations (10–12 years) to achieve high yields. The primary differences in managing woody feedstocks for bioenergy production vs for pulp/sawtimber production include a higher frequency of pesticide and fertilizer applications, whole-tree removal, and greater ground disturbance (i.e., more bare ground during stand establishment and more frequent disturbance). And while the effects of pulp/sawtimber production on water quality are well-studied, the effects of growing short-rotation loblolly pine on water quality and the efficacy of current forestry Best Management Practices (BMPs) have not been evaluated for this emerging management system. We used a watershed-scale experiment in a before-after, control-impact design to evaluate the effects of growing loblolly pine for bioenergy on water quality in the Upper Coastal Plain of the southeastern U.S. Intensive management for bioenergy production and implementation of current forestry BMPs occurred on ~50% of two treatment watersheds, with one reference watershed in a minimally managed pine forest. Water quality metrics (nutrient and pesticide concentrations) were measured in stream water, groundwater, andmore » interflow (i.e., shallow subsurface flow) for a two-year pre-treatment period, and for 3.5 years post-treatment. After 3.5 years, there was little change to stream water quality. Here, we report on observations where there were a few occurrences of saturated overland flow, but there were sediments and water dissipated within the streamside management zones in over 75% of these instances. Stream nutrient concentrations were low and temporal changes mainly reflected seasonal patterns in nitrogen cycling. Nitrate concentrations increased in groundwater post-treatment to < 2 mg N L -1, and these concentrations were below the U.S. drinking water standard (10 mg N L -1). Applied pesticides were almost always below detection in streams and groundwater. Overall, these findings highlight that current forestry BMPs can protect stream water quality from intensive pine management for bioenergy in the first 3.5 years. However, groundwater quality and transit times need to be considered in these low-gradient watersheds of the southeastern U.S. that are likely to become an important location for woody bioenergy feedstock production.« less
Authors:
 [1] ;  [2] ;  [2] ;  [3] ;  [2] ;  [3] ;  [3]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Climate Change Science Inst. and Environmental Sciences Division
  2. Univ. of Georgia, Athens, GA (United States). Warnell School of Forestry and Natural Resources
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division
Publication Date:
Grant/Contract Number:
AC05-00OR22725; AI09-00SR22188
Type:
Accepted Manuscript
Journal Name:
Forest Ecology and Management
Additional Journal Information:
Journal Volume: 400; Journal Issue: C; Journal ID: ISSN 0378-1127
Publisher:
Elsevier
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Bioenergy Technologies Office (EE-3B)
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; 54 ENVIRONMENTAL SCIENCES; Intensive silviculture; Short-rotation woody crops; Nitrogen; Concentrated flow tracks; Interflow; Surface water
OSTI Identifier:
1362217