Modeling combined effects of forestry, agriculture and deposition on nitrogen export in a northern river basin in Finland

Citation
A. Lepisto et al., Modeling combined effects of forestry, agriculture and deposition on nitrogen export in a northern river basin in Finland, AMBIO, 30(6), 2001, pp. 338-348
Citations number
52
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Environment/Ecology,"Environmental Engineering & Energy
Journal title
AMBIO
ISSN journal
0044-7447 → ACNP
Volume
30
Issue
6
Year of publication
2001
Pages
338 - 348
Database
ISI
SICI code
0044-7447(200109)30:6<338:MCEOFA>2.0.ZU;2-8
Abstract
The development of the spatial N export and retention model N_EXRET for lar ge river basins is presented, utilizing remote-sensing-based land use and f orest classification. Export coefficients describing the contribution from agriculture, forestry and peat harvesting were estimated based on empirical studies. Representativeness of forest treatment coefficients have been eva luated by use of data from a small, well-documented test catchment. Simulat ion results from the application of the model to the Oulujoki river basin ( 22 840 km(2)) are discussed. Model estimated N fluxes were compared with me asured N fluxes in separate points of the river basin. Based on source appo rtionment, agriculture contributes 17% of the total export, varying between 8% in the uppermost subbasin and 38% in the lowermost subbasin close to th e sea. Forestry contributes almost as much, 16%, with less pronounced varia tion (11-24%) between the different subbasins. In the separate subbasins, 7 -37% of the incoming gross N export was retained. Based on mass balances an d sensitivity analyses, retention was estimated to be in the range of 5-10 kg ha(-1)yr(-1) in lakes and 0-1 kg ha(-1)yr(-1) in peatlands. The model re sults were validated by testing to data from the 3 closely situated river b asins. However, further testing is needed in river basins where land use an d deposition patterns differ clearly from these northern basins.