Nutrient fluxes through a boreal coniferous forest and the effects of clear-cutting (väitöskirja/dissertation).

Piirainen, Sirpa. 2002
Metsäntutkimuslaitoksen tiedonantoja 859. 50 p. + Papers I-V.
[ISBN 951-40-1839-7]
[Maksuton, toimituskulut 5 eur] Tilaa tiedonanto

Asiasanat:

base cations, carbon, deposition, harvesting, nitrogen, phosphorus, soil water

Sisällys:

Tiivistelmä:

The objective of this thesis was to study the impact of practical clear-cutting (stem only) on the fluxes of the major plant nutrients: C, N, P, S, Ca, Mg and K, through a podzolic soil in a Norway spruce dominated mixed boreal forest. Changes in deposition, litterfall and, after clear-cutting, logging residue inputs of nutrients to the soil were also included. Data presented were collected from three sample plots during 1993 - 1999 situated in eastern Finland. The clear-cutting was carried out in September 1996 at two of the plots. Litterfall, bulk deposition, throughfall, stemflow and soil percolate from below different soil horizons before and after clear-cutting were collected at the sample plots. Increased flux of dissolved organic carbon (DOC) from below the organic (O) horizon was observed after cutting. However, the flux (168 kg C ha-1 a-1) was small compared to the amount in the logging residues. The flux of DOC from below the illuvial (B) horizon (3 kg ha-1 a-1) was not affected by cutting. The deposition of total N (DTN) was small (4 kg ha-1 a-1), and the flux of dissolved inorganic N compounds through the soil was also small. After cutting some increased formation of NH4+ and NO3- was observed. However, the DTN flux from below the B-horizon (0.2 kg ha-1 a-1) did not increase markedly after clear-cutting and the main fraction was organic N, as also before cutting. Increased fluxes of P and K from below the O-horizon were observed after cutting and the fluxes were the highest in the first year. The P retention capacity of the mineral soil was considerable and no significant increased fluxes of P from below the B-horizon (0.01 kg ha-1 a-1) were observed. Increased fluxes of K and Mg from below the B-horizon (1.6 kg K ha-1 a-1; 0.1 kg Mg ha-1 a-1) were occasionally observed. The deposition of S (2.0 kg ha-1 a-1) due to clear-cutting (loss of canopy interaction) decreased the flux of S from below the O-horizon, as also from below the B-horizon (0.7 kg ha-1 a-1).

Yksikkö: Joensuun tutkimuskeskus
Hanke: Päätehakkuun vaikutus kangasmetsän vesi-, hiili- ja ravinnevirtoihin ja -varastoihin