Section 57
Chapter 56,577

Throughfall deposition and canopy exchange processes along a vertical gradient within the canopy of beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst)

Adriaenssens, S.; Hansen, K.; Staelens, J.; Wuyts, K.; De Schrijver, A.; Baeten, L.; Boeckx, P.; Samson, R.; Verheyen, K.

Science of the Total Environment 420: 168-182


ISSN/ISBN: 0048-9697
PMID: 22325986
DOI: 10.1016/j.scitotenv.2011.12.029
Accession: 056576856

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To assess the impact of air pollution on forest ecosystems, the canopy is usually considered as a constant single layer in interaction with the atmosphere and incident rain, which could influence the measurement accuracy. In this study the variation of througfall deposition and derived dry deposition and canopy exchange were studied along a vertical gradient in the canopy of one European beech (Fagus sylvaticaL.) tree and two Norway spruce (Picea abies(L.) Karst) trees. Throughfall and net throughfall deposition of all ions other than Hincreased significantly with canopy depth in the middle and lower canopy of the beech tree and in the whole canopy of the spruce trees. Moreover, throughfall and net throughfall of all ions in the spruce canopy decreased with increasing distance to the trunk. Dry deposition occurred mainly in the upper canopy and was highest during the growing season for H, NH4, NO3and highest during the dormant season for Na, Cl, SO4(beech and spruce) and K, Caand Mg(spruce only). Canopy leaching of K, Caand Mgwas observed at all canopy levels and was higher for the beech tree compared to the spruce trees. Canopy uptake of inorganic nitrogen and Hoccurred mainly in the upper canopy, although significant canopy uptake was found in the middle canopy as well. Canopy exchange was always higher during the growing season compared to the dormant season. This spatial and temporal variation indicates that biogeochemical deposition models would benefit from a multilayer approach for shade-tolerant tree species such as beech and spruce.We assess dry deposition and canopy exchange within a beech and two spruce canopies. Throughfall water was sampled along a vertical gradient and throughout the year. Dry deposition was highest in the upper canopy, as for canopy uptake of nitrogen. Canopy leaching occurred over the whole canopy. A multilayer approach is recommended for biogeochemical deposition models..

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