Submitted to: World Agroforestry Congress
Publication Type: Abstract Only
Publication Acceptance Date: 7/2/2004
Publication Date: 7/2/2004
Citation: Thomas, A.L., Defauw, S.L., Sauer, T.J., Brauer, D.K. 2004. Hydrologic influences on the growth of young grafted black walnut trees [abstract]. World Agroforestry Congress. p. 213. Interpretive Summary:
Technical Abstract: An Eastern Black Walnut (Juglans nigra) plantation consisting of 91 trees was established in the Fall of 1999 at a site in Northwestern Arkansas. Two-year old seedlings (pre-grafted to improved nut-producing cultivars) were transplanted with a spacing of 9.1 m within and 15.2 m between rows. Tree girth at 25 cm above the graft (N=52) was determined at the conclusion of the growing seasons in 2002 and 2003 for all surviving trees with surviving grafts. Each tree position was mapped and growth data were linked to a GIS database (ArcView 3.2a) established for the shallow ground water monitoring of a 4.25 ha silvopastoral field. Eighteen wells with depths varying from 0.51-3.48 m beneath the land surface datum were installed (from 2000-2001) in this 1.22 ha (3 acre) zone. Monitoring efforts (N=21) during the last two growing seasons (March-September 2002-2003) have revealed that 13 out of 18 wells have mean water table levels of less than 1.00 m beneath the surface, which challenges the characterization of 'dry upland site'. Four wells have hydrodynamic ranges in excess of 1.50 m (with subsurface fluctuations varying from 1.69-3.20 m); young trees in the vicinity of these wells are exhibiting substandard growth due to water deficit stress (with negative departures within 1-3 standard deviations from the mean 2-year girth increase of 15.4 mm). Preliminary geospatial analyses suggest that young trees emplaced in areas where the mean water table ranges from approximately 0.8-1.3 m are exhibiting the best growth on the plantation.