Suo - Mires and peat vol. 52 no. 3-4 | 2001
Metaanivuo länsi-siperialaiselta suolta.
English title: CH4 emissions from a West Siberian mire.
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Northern wetlands are an important source of the greenhouse gas CH4. We studied CH4 turnover in an oligotrophic mire near the Yenisej River in West Siberia in July 1996. CH4 emissions were determined using closed chambers. CH4 production and CH4 oxidation potentials were estimated from flask incubations. Mean CH4 emissions from lawn and mudbottoms were 117±19 mg m–2 d–1 (SE; n=47). CH4 concentrations, CH4 production and CH4 oxidation potentials in lawn samples were high, indicating that CH4 oxidation might be important in controlling CH4 emissions from this mire. Ridges showed low values in all parameters including CH4 emissions. The area-weighted estimate for the mire was 80 mg m–2 d–1, which makes this an area of medium to high CH4 emission. For the surrounding pine forest soil, a CH4 sink of about –1 mg m–2 d–1 was estimated, a value similar to that in other boreal forest soils. The area-weighted estimate for ca. 360 km2 of mire and forest around the site was a CH4 emission of at least 25 mg CH4 m–2 d–1 during summertime.
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Bosse,
Biology Department, Carleton University, Ottawa, ON K1S 5B6, Canada
Sähköposti:
ei.tietoa@nn.oo
- Frenzel, Sähköposti: ei.tietoa@nn.oo
Ojitettujen suokuusikoiden ravinnetarpeen määritys neulasanalyysillä.
English title: Nutritional diagnosis of Norway spruce stands growing on drained peatlands using foliar analysis.
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The purpose of this study was to determine critical nutrient concentration values for interpreting foliar analysis of Norway spruce stands growing on drained peatlands. During 1987–91, a total of 162 spruce needle samples from various peatland sites in Finland were taken and analysed for N, P, K, Ca, Mg, B, Cu, Fe, Mn and Zn. The mean height growth of the two preceding growing seasons was used as the growth parameter for multiple and simple regression analyses. Foliar concentrations significantly explained height growth. Simple regression analysis was used to estimate the following critical values indicating severe to moderate nutrient deficiencies for the main nutrients: N 1.15–1.30%, P 1.70–2.30 mg g-1 and K 5.40–6.60 mg g-1. Also the following tentative critical concentrations are suggested: Cu 2.0 mg kg-1, Fe 13.0 mg kg-1, Mg 0.80 mg g-1 and Zn 16.0 mg kg-1. Results for B are in accordance with previous, but unsubstantiated, critical values (6–8 mg g-1).
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Veijalainen,
The Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland
Sähköposti:
ei.tietoa@nn.oo
Terveyslannoituskohteen määrittely turvemailla.
English title: Determining the need of repairing fertilization on drained peatlands.
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In Finland there are approximately one million hectares of nitrogen-rich drained mires which may suffer from deficiency of potassium (and phosphorus). These site types are originally wet sedge fens with thick peat layers. The degree of deficiency of mineral nutrients varies, but it is propable that fertilizing with potassium and phosphorus would improve growth in most cases. This kind of fertilization which aims at rebalancing available nutrient stores for trees is called “repairing fertilization”. However, it is almost impossible to say when there is a question of repairing fertilization or normal fertilization meant to improve growth. This study introduced the assessment of repairing fertilization plan simultaneously with different methods to determine the need of such a fertilization. Earlier instructions emphasize visible potassium and phosphorus deficiency symptoms or needle analyses. However, these methods alone do not provide enough information to reliably determine the need of fertilization. For example the limit of severe potassium deficiency in Norway spruce needle analysis is 5.2 mg g-1 while visible deficiency symptoms will not be apparent until the value drops down to 4.0 mg g-1. In other words spruce may suffer from severe potassium deficiency long before it can be seen by human eyes. The problem of needle analysis is commonly it‘s reliability as needles are collected only from 5–10 trees per site.
The results indicate that determining the need of repairing fertilization should be based on both the mire site type (sedge fens) and the thickness of the peat layer (over 0.4–0.5 meter). Determining the need of repairing fertilization on drained mires should not be solely based on the needle analysis and visible potassium deficiency symptoms as the case has been so far.
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Silver,
Sähköposti:
ei.tietoa@nn.oo
- Saarinen, Sähköposti: ei.tietoa@nn.oo
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