Soil CO2 efflux and water use efficiency across diverse cover types in southern Appalachian hardwood forestsThis article is part of a larger document. View the larger document here.
We are investigating biogeochemical cycling in a mixed hardwood forest in the Ridge and Valley physiographic province in Montgomery County, Virginia. The broad aim of the study is to understand how carbon, water and nutrient cycles vary among diverse stand types in a relatively small spatial area. The specific objectives here are to determine patterns in soil CO2 efflux or respiration (Rs) and water use efficiency among cover types. Four 0.02 ha sample plots, replicated four times, were established in four cover types – white oak (WO, Quercus alba), Scarlet oak (SO, Q, coccinea), chestnut oak (CO, Q. montana) and mixed pine – oak (PO, Pinus spp., Quercus spp.). In each plot, diameter at breast height was measured on all trees greater than 5.1 cm. Rs was measured monthly. Foliage from two dominant or co-dominant trees in each plot was sampled for water use efficiency using d13C discrimination analysis. Soil temperature alone explained 93 percent of the variation in Rs and the variance due to cover type was not significant. Water use efficiency was greatest in SO where d13C was -26.6 per- mille which was significant different than CO (-28.3) and WO (-28.5) values.