ABOVEGROUND NET PRIMARY PRODUCTIVITY AND NITROGEN MINERALIZATION IN A MIXED MESOPHYTIC FOREST OF EASTERN KENTUCKY

Above-ground net primary productivity (ANPP) and potential nitrogen (N) mineralization were measured in four forest types along a soil fertility gradient in eastern Kentucky to test the hypothesis that ANPP in the mixed mesophytic forest region is related to both species composition and mineralizable N. N mineralization differed significantly among the four forest types, with the lowest values occurring on sites containing oak forest and the highest rates occurring on sites containing a mixed mesophytic forest. However, ANPP did not differ among forest types, and was unrelated to mineralizable N. ANPP averaged 6306 kg ha-1 year-1, of which 56% was woody production and 44% was above-ground litter production. The poor relationship between ANPP and site fertility may reflect differential patterns of nutrient use efficiency among the deciduous species which make up the vegetation gradients of eastern Kentucky.