THE HUBBARD BROOK ECOSYSTEM STUDY - BIOGEOCHEMISTRY OF LEAD IN THE NORTHERN HARDWOOD FOREST

The average annual Pb input to the northern hardwood forest at the Hubbard Brook Experimental Forest in central New Hampshire was 266 g ha** minus **1 year** minus **1 based on 4 years of records. Lead output via stream-water and eroded particulate matter was 5. 0 and 1. 1 g ha** minus **1 year** minus **1, respectively. Lead concentration in precipitation averaged 22 mu g liter** minus **1 and showed a significant decline over the 4 sample years (1975-1978). Lead input to the ecosystem via meteorological vectors is accumulated in the forest floor. Within the forest floor, maximum Pb concentration is in the fermented layer. Total Pb content of the forest biomass was 1,248 g ha** minus **1. The order of lead concentration in the biota is given in the paper. Disturbance of the forest ecosystem through harvest cutting, other than through increased runoff, increased erosion, and transport of particulate matter, does not alter the biogeochemistry of Pb and does not result in increased mobility and export of Pb due to gross or subtle alternations of the behavior of Pb in the ecosystem.