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

Abstract

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:

Griffiths, Natalie A. ^[1]; Jackson, C. Rhett ^[2]; Bitew, Menberu M. ^[2]; Fortner, Allison M. ^[1]; Fouts, Kevin L. ^[2]; McCracken, Kitty ^[1]; Phillips, Jana R. ^[1]

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+ Show Author Affiliations

1. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
2. University of Georgia, Athens, GA (United States)

Publication Date:

Mon Jun 12 00:00:00 EDT 2017

Research Org.:

Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE), Sustainable Transportation Office. Bioenergy Technologies Office

Contributing Org.:

USDA Forest Service-Savannah River, New Ellenton, SC

OSTI Identifier:

1362217

Alternate Identifier(s):

OSTI ID: 1495796; OSTI ID: 1572176

Report Number(s):

17-16-P
Journal ID: ISSN 0378-1127

Grant/Contract Number:  

AC05-00OR22725; EM0003622; AI09-00SR22188

Resource 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

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