TREE SHELTER AND INTERPLANTED N-FIXING SHRUB EFFECTS ON CROP TREE GROWTH ON A CALCAREOUS MINESOIL

Abstract

In southeastern Ohio, we installed three studies to test the effects of plastic tube tree shelters and interplanted N-fixing shrubs on crop tree survival and growth. Study 1 on graded gray cast overburden used white ash (Fraxinus Americana L.) and a hybrid willow (Salix matsudana x alba, or Austree) as crop trees. These were tested in factorial combination with 1.2 m tall tree shelters (present or absent) and N-fixing shrubs [none, bristly locust (Robinia fertilis Ashe), or Siberian peashrub (Caragana arborescens Lam. )]. Study 2 evaluated growth of bur oak (Quercus macrocarpa Michx.) as affected by soil surf ace (graded cast overburden or ripped topsoil), presence of tree shelters, and presence of interplanted Siberian peashrub. Study 3 tested Austree growth as affected by soil surf ace and presence of tree shelters. After four or five growing seasons, overall crop tree survivals were white ash (80%), bur oak (52%), and Austree (10% in study 1 and 25% in study 3). All crop tree species tended to survive better with tree shelters but only Austree in study 3 (36% with shelter vs. 14% without shelter) showed a significant difference. Tree shelters increased heights of white ash (102 cm with shelter vs. 21more » cm without shelter) and bur oak (84 cm vs. 27 cm). Crop tree survival and growth were not affected significantly by interplanted N-fixing shrubs or by soil surface. In study 1 (cast overburden only), peashrub (64%) survived better than bristly locust (31%) but locust was taller (74 cm vs. 45 cm). In study 2, peashrub survived better on ripped topsoil (53%) than cast overburden (17%), but height was not impressive on either soil (41{+-}11 cm).« less