N deposition, N transformation and N leaching in acid forest soils

Autor: Séverine Bienaimé, Micheline Colin-Belgrand, Bernd Zeller, Jean-Hugues Jussy, Jacques Ranger, Etienne Dambrine
Přispěvatelé: Unité de recherche Biogéochimie des Ecosystèmes Forestiers (BEF), Institut National de la Recherche Agronomique (INRA)
Rok vydání: 2004
Předmět:
Zdroj: Biogeochemistry
Biogeochemistry, Springer Verlag, 2004, 69 (2), pp.241-262. ⟨10.1023/B:BIOG.0000031050.13663.82⟩
ISSN: 0168-2563
1573-515X
Popis: International audience; Nitrogen deposition, mineralisation, uptake and leaching were measured on a monthly basis in the field during 2 years in six forested stands on acidic soils under mountainous climate. Studies were conducted in three Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] plantations (D20: 20 year; D40: 40 yr; D60: 60 yr) on abandoned croplands in the Beaujolais Mounts; and two spruce (Picea abies Karst.) plantations (S45: 45 yr; S90: 90 yr) and an old beech (Fagus sylvatica L.) stand (B150: 150 yr) on ancient forest soils in a small catchment in the Vosges Mountains. N deposition in throughfall varied between 7–8 kg ha–1 year–1 (D20, B150, S45) and 15–21 kg ha–1 yr–1 (S90, D40, D60). N in annual litterfall varied between 20–29 kg ha–1 (D40, D60, S90), and 36–43 kg ha–1 (D20, S45, B150). N leaching below root depth varied among stands within a much larger range, between 1–9 kg ha–1 yr–1 (B150, S45, D60) and 28–66 kg ha–1 yr–1 (D40, S90, D20), with no simple relationship with N deposition, or N deposition minus N storage in stand biomass. N mineralisation was between 57–121 kg ha–1 yr–1 (S45, D40, S90) and between 176–209 kg ha–1 yr–1 in (B150, D60 and D20). The amounts of nitrogen annually mineralised and nitrified were positively related. Neither general soil parameters, such as pH, soil type, base saturation and C:N ratio, nor deposition in throughfall or litterfall were simply related to the intensity of mineralisation and/or nitrification. When root uptake was not allowed, nitrate leaching increased by 11 kg ha–1 yr–1 at S45, 36 kg ha–1 yr–1 at S90 and between 69 and 91 kg ha–1 yr–1 at D20, D40, B150 and D60, in relation to the nitrification rates of each plot. From this data set and recent data from the literature, we suggest that: high nitrification and nitrate leaching in Douglas-fir soils was likely related to the former agricultural land use. High nitrification rate but very low nitrate leaching in the old beech soil was related to intense recycling of mineralised N by beech roots. Medium nitrification and nitrate leaching in the old spruce stand was related to the average level of N deposition and to the deposition and declining health of the stand. Very low nitrification and N leaching in the young spruce stand were considered representative of fast growing spruce plantations receiving low N deposition on acidic soils of ancient coniferous forests. Consequently, we suggest that past land use and fine root cycling (which is dependent on to tree species and health) should be taken into account to explain the variability in the relation between N deposition and leaching in forests.
Databáze: OpenAIRE
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