Determining water use by common trees across North Carolina can help develop planting guidelines
Different forest tree species use water differently—for example, Forest Service scientists found that oaks use less water than any of the other common species studied in North Carolina. Knowledge of these differences can help land and water resource managers determine how best to set streamflow targets to sustain aquatic habitats and provide for downstream needs.
Forests cover 60 percent of North Carolina’s land surface, about 40 percent of which consists of hardwood forest. Softwood or conifer trees make up the next dominant forest type at 30 percent, while mixed stands of oak-pine and oak-gum-cypress cover the remaining 30 percent. Water use or transpiration by these trees varies across North Carolina and by species, due to unique climates and topographic conditions in different regions—mountain, Piedmont, and coastal plain—and unique tree species physiologies. Forest Service scientists used sapflow sensors to quantify water use by some common North Carolina trees—loblolly pine (Pinus taeda), longleaf pine (Pinus palustris), oaks (Quercus spp.), sweetgum (Liquidambar styraciflua), red maple (Acer rubrum), and tulip poplar (Liriodendron tulipifera). Results show that oak trees consistently use less water than all other species regardless of region. For example, in the Piedmont a seven inch diameter oak tree used three gallons of water per day while a similar sized tulip poplar and red maple used ten and 14 gallons of water per day, respectively. Red maple trees in the Piedmont used one and a half times more water than maples in the coastal plain. There are over 14 billion trees in North Carolina; continuing to help our partners and water resource managers understand how water moves through these forests will be crucial for developing future species planting guidelines.
Pictured: USDA Forest Service scientist Johnny Boggs explains how to measure tree water use with sapflow sensors.
External Partners/Collaborators: North Carolina Forest Service, North Carolina State University, North Carolina Department of Agriculture and Consumer Services.
Contact: Johnny Boggs, Biological Scientist, Eastern Forest Environmental Threat Assessment Center, johnny.boggs@usda.gov.
