Effects of species conversion on transpiration and streamflow in the Piedmont of North Carolina

PARTNERS: North Carolina Forest Service; North Carolina State University; North Carolina Department of Agriculture and Consumer Services

SUMMARY: In the 1950s there were virtually no pine plantations in the southern United States. Now there are over 39 million acres of planted pine with most of that expansion occurring over the last twenty five years. Land management practices that include species conversion or vegetation manipulation to meet rising wood demands and biofuel market needs can have consequences to surface water availability and groundwater recharge through altered transpiration (i.e., water use) processes.

Data quantifying changes in stream discharge and tree transpiration following the conversion of mixed pine-hardwood stands to single species stands in the North Carolina Piedmont are limited. As biofuel and other timber markets continue to emerge, species conversion studies need to be further explored as options to meet energy and wood production needs without compromising the quantity of water resources and their aquatic benefits.

EFETAC's ROLE: Eastern Threat Center biological scientist Johnny Boggs leads this research project.

STATUS: Ongoing

PROGRESS: In 2010, two mixed-pine hardwood stands were clearcut from two North Carolina Piedmont watersheds. Later in 2010, one watershed was replanted with loblolly pine trees and the other was replanted with shortleaf pine trees. Researchers are monitoring continuous transpiration, streamflow, and soil moisture from both watersheds to determine how runoff and water use will change now that the stand has be converted from hardwoods to pines.

In 2013, researchers began measuring annual tree growth and monthly leaf area index. They will link biomass changes and land cover conditions to water balances and stream discharge rates. Flow monitoring and vegetation surveys will likely continue through 2025.

Results from this work will refine what is known about the effects of vegetation manipulation and regrowth on headwater catchment hydrology in the Piedmont of North Carolina and expand the understanding of how managers can most effectively sustain forest and water resources following silvicultural activities.


Pictured: Researchers will link biomass changes and land cover conditions to water balances and stream discharge rates. Click to enlarge.


Johnny Boggs, Eastern Threat Center Biological Scientist, johnny.boggs@usda.gov or 919-549-4060

Updated July 2018

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