Nutrient cycling in secondary plant succession in a humid tropical forest region (Turrialba, Costa Rica) / Paul Albin Harcombe.

Tese (Ph.D.)-- Yale University, 1973.

A two-hectare area of tropical moist forest was clear felled, and an experiment was set up to test the following hypotheses: (1) that nutrient loss is significant during the first year following forest clearing, (2) that vegetation presence retards this loss, and (3) that nutrient loss is inversely related to rate of biomass accumulation. Experimental treatments included maintaining plots free of vegetation, allowing regeneration of successional vegetation from seed, and planting seedlings of Cecropia obtusifolia Bertol.; half the plots were fertilized to stimulate growth. Results indicate that nutrient loss occurred, that it was diminished by vegetation cover, but that it was not strongly related to amount of biomass accumulated in the first year. Succession was altered by fertilization, and the altered species composition resulted in differences in vegetation biomass and nutrient content. However, nutrient loss was not related to species composition, vegetation biomass, or vegetation nutrient content. To account for these results, it is hypothesized that levels of semi-available soil nutrients or of nutrient inputs may be as influential in determining the rate of vegetation recovery following forest disturbance as are levels of available soil nutrients.