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Goal: Apply Knowledge Globally Sustainable production of short-rotation woody crops on marginal lands

Technicions installing sap flow probes in Eastern cottonwood stems

Forest Service technician Shelly Hei-Kyung Hooke installing sap flow probes in Populus deltoides stems. (Forest Service photo by Chris Maier)

Introduction

Short-rotation woody crops (SRWC) are potentially an environmentally acceptable and economically sustainable method of producing wood for bioenergy, biofuels, and bioproducts. SRWC will likely be located on marginal sites that may face challenges from resource management (i.e., nutrients and water) and climate change. SRS scientists are working with collaborators in the U.S. and Chile to understand the ecological and economic functioning of SRWC systems.

Summary

Increased demand for wood biomass for bioenergy in the South may exceed supply from conventional forestry. Short-rotation woody crops can help fill this gap with appropriate species (e.g., Populus, Eucalyptus, Pinus). SRWC systems will likely be located on marginal land unsuitable for agriculture. However, low productivity and long rotations combined with high establishment and maintenance costs may limit profitability. The potential of SRWC systems is tied to their use of site resources and tolerance to changes in climate like multi-year droughts and extended periods of cold or heat. SRS scientists and collaborators from Virginia Tech, North Carolina State University, and the University of Concepcion, Chile are studying the biological potential and economics of SRWC systems.

Early results indicate that productivity and resource use efficiency are positively correlated. Furthermore, high and low density plantings (2,020 vs. 6,070 trees per acre) produced the same amount of biomass after five years. Planting at lower densities would reduce establishment costs. However, SRWC have high transpiration rates that exceed precipitation inputs in some cases. High water use may adversely affect groundwater and water yield in sensitive areas.

The research team is currently refining silvicultural practices that maximize resource use efficiency and economic potential of SRWC. Scientists are also investigating potential impacts to other ecosystem services such as soil stabilization, water quality, and carbon sequestration.