Establishment of Upland and Bottomland Hardwood Agroforestry Plantations in Tennessee and Mississippi

The feasibility of alley cropping as a means of afforestation was studied across seven different study sites in western Tennessee and northern Mississippi. Seeds were collected from 11 oak (Quercus spp) species and black walnut (Jug/ans nigra L.) trees in the region and grown under nursery protocols that are designed to produce seedlings of optimal size in one year. Seedlings were lifted by genetic family after one year and initial seedling measurements were recorded. Four bottomland studies and three upland studies were then sorted into an incomplete block design with multiple species and families within each block. Seedlings were planted by augers in an alley cropping design during the spring of 2003. Shortly after flushing, two of the bottomland sites were completely inundated by backwater flooding from Mississippi River tributaries for up to three weeks. The other two bottomland studies experienced soil saturation into June. First year growth, survival, and damage was recorded in the fall of 2003. First year survival on bottomland sites was clearly affected by flood intensity and revealed a clear flood tolerance differentiation among species. Survival fell from 90 percent on one of the saturated sites to 35 percent on the most severely flooded site. Nuttall oak (Quercus texana Buckley), willow oak (Quercus phellos L.), swamp chestnut oak (Quercus michauxii Nutt.), and bur oak (Quercus macrocarpa Michx.) generally had the greatest survival across sites and appeared the least affected by flooding. The survival of all species increased with increasing root collar diameters and first order lateral roots. Each bottomland site had an overall negative height growth (dieback) ranging from -14 to -62 cm. Water oak (Quercus nigra L.) and willow oak generally had the greatest amount of dieback. Height growth did not follow the flood tolerance of species as closely as survival, but was clearly affected by initial height in a negative relationship and root collar diameter and first order lateral roots in a positive relationship. Basal sprouting was a common response of water oak and willow oak to flooding and appeared to increase as flood severity increased to a certain point and then declined. Upland survival was greater than 90 percent across study sites. Height growth means were good across sites except for the dieback on the northern red oak study site (Quercus rubra L.), which was probably due to late planting and drier than average roots at the time of planting. Soybeans were planted between the tree rows on three sites. Soybean production was lower overall than the previous year, but still helped offset the cost of seedling establishment