Selecting the right shade-tolerant forages for restoring savannas or woodlands and implementing different agroforestry practices
Ground covers of forage, native grasses, and legumes provide nutrients, especially nitrogen, to facilitate tree growth. Selection of these species for use as ground covers is enhanced when shade tolerance of the ground covers is known. Forest Service scientists screened 43 species of native and introduced legumes and grasses multiple times under three levels of shade cloth in the absence of competition from tree roots. They found that annual biomass yields for all forages did not statistically differ when grown under 45 and 100 percent of ambient sunlight. Thirty-one of the species also had no statistical differences in annual yields when grown under 20 and 100 percent of ambient sunlight. When shade tolerance was measured as yield under different light intensities, cool-season grasses were found to have the greatest shade tolerance. Cool-season legumes had the least shade tolerance, while warm-season grasses and legumes were on average intermediate to the cool-season forages. Research results suggest most forages can perform as well under shade of open-grown trees (if tree root competition can be minimized) as under full sun, providing land managers with a wide selection of forage and legume species they can use to achieve desired results when implementing agroforestry practices or restoring savannas or woodlands.
Forest Service Partners