tailieunhanh - Báo cáo khoa học: "Canopy uptake of N deposition in spruce (Picea abies L. Karst) stands"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: Canopy uptake of N deposition in spruce (Picea abies L. Karst) stands. | 113 Ann. For. Sci. 57 2000 113-120 INRA EDP Sciences Original article Canopy uptake of N deposition in spruce Picea abies L. Karst stands Nadia Ignatovaa and Étienne Dambrineb a Silviculture University 1056 Sofia Bulgaria b CRF-INRA Équipe Cycle Biogéochimique 54280 Champenoux France Received 10 March 1999 accepted 4 November 1999 Abstract - In order to quantify the total deposition and canopy uptake of N in spruce plastic Christmas trees were established next to real spruce trees of approximately similar height in clearings of the Strengbach catchment Vosges mountains France . Bulk precipitation and throughfall TF composition under the artificial trees the real spruce trees and in 3 spruce stands aged 15 35 and 90 years were monitored during months. Fluxes of inorganic N SO42- and Na in throughfall below plastic trees were 50 N to 30 Na higher to those in bulk precipitation whereas the flux of water was 30 lower. Net throughfall NTF fluxes of NH4 were higher below the plastic trees than below the real trees whereas the reverse was true for NO3-. The ratio between total inorganic nitrogen and Na or SO42- in NTF was higher below plastic trees than below closed spruce stands. Assuming that foliar leaching of Na or SO42- was negligible the ratios between Na or SO42- fluxes in net throughfall under living and plastic canopies were used as deposition indexes and dry occult deposition of N was computed for the real spruce trees in the clearings as well as in the 3 closed stands. Results confirmed a significant canopy uptake of dry occult deposited N and especially NH4 by spruce stands. dry deposition nitrogen throughfall net throughfall Picea abies Résumé - Absorption foliaire des depots azotes par des peuplements d épicéa. Afin de quantifier le dépôt et l absorption foliaire d azote dans des peuplements d épicéa Picea abies L. Karst nous avons placé des arbres de Noel en plastique à coté de jeunes épicéa de taille identique dans deux clairières du bassin versant du