The Organic Matter and Nutrient Elements in the Precipitation Beneath a Sessile Oak (Quercus Petraea) Canopy

Abstract

The nutrient, carbon and energy contents of the incident rainfall above the tree canopy and of the throughfall beneath it were measured in a sessile oak (Quercus petraea) woodland on a siliceous site in a high rainfall (171 cm/annum) area. The N, P, K, Ca, Mg, and Na contents of the incident rainfall were 9.54, 0.43, 2.96, 7.30, 4.63 and 35.34 kg/ha/annum, respectively; the contents of these elements in the throughfall were 8.82, 1.31, 28.14, 17.18, 9.36 and 55.55 kg/ha/annum, respectively. The total amounts of these elements falling to be ground layer in the throughfall and litter were 49.88, 3.50, 38.65, 41.01, 13.23 and 57.22 kg/ha/annum, respectively; the total energy content of the organic matter in the litter and throughfall was 21.11 x 106 kcal/ha/annum. Large amounts (67.80 kg/ha/month) of carbohydrate came down in the throughfall in Aug., consisting mainly of melezitose, a trisaccharide found in honeydew. 17.7% of the N, 37.4% P, 72.8% K, 41.9% Ca, 70.7% Mg and 97.1% Na in the litter+ throughfall was present in the throughfall. Inorganic N and P were removed from the precipitation as it passed through the tree canopy, and there was evidence of a complex exchange system between the tree and the rainfall. Not all the materials added to the throughfall were necessarily leached from the leaf and branch tissue, but could have originated partly from compounds adsorbed on the plant surfaces.