Artikkelit jotka sisältää sanan 'peat nitrogen'

The total peat nitrogen (N) concentration is an important factor when determining stand heights and volumes in areas of poor climate conditions. This study explores the effect of peat nitrogen on the height and volume of Scots pine (Pinus sylvestris L.) stands in drained peatland sites in three temperature sum regions (Susivaara 909, Hepokangas 930, and Haapua 987 dd) in northern Finland. The peat nitrogen concentration ranged from 0.7% to 3.0%. In all experimental fields, the concentrations of foliar nutrients (nitrogen (N), potassium (K), phosphorus (P), and boron (B)) were analyzed. A total of 550 peat samples, 440 foliar samples, and 1687 sample trees were measured. We found nitrogen deficiencies in the foliar samples of all experimental fields. At Haapua, the stands were the highest, about 140 dm, when the peat N-concentration was at its maximum (3.0%). In the areas of Susivaara and Hepokangas, the stand heights were lower than in Haapua, about 90 dm, when N-concentrations of peat were at their maximum (2.5% and 2.8%). The stand volumes were largest at Haapua (about 190 m3/ha, N = 3.0%). At Susivaara (80 m3/ha, N = 2.5%) and Hepokangas (70 m3/ha, N = 2.8%), lower stand volumes were measured. We found a strong positive relationship between peat N-concentration and stand height as well as stand volume at Hepokangas and Haapua. At Susivaara, however, this relationship was weak. The results show that the total peat nitrogen concentration strongly affects stand height and volume on drained peatlands. The information of this study can be utilized, for example, when assessing the feasibility of forest management practices, such as the profitability of ditch network maintenance and fertilizations on peatlands.

• Korkalainen, University of Joensuu, Department of Geography, P.O. Box 111, 80101 Joensuu, Finland Sähköposti: ei.tietoa@nn.oo
• Pietiläinen, Sähköposti: ei.tietoa@nn.oo
• Colpaert, Sähköposti: ei.tietoa@nn.oo

Wood production capacity on drained peatlands depends on the site type and temperature sum. Site type is closely related to the peat total nitrogen concentration. This study aims at clarifying the effect of peat nitrogen, fertilization and refertilization on the foliar nitrogen concentration of Scots pine in different temperature sum conditions (850, 950 and 1080 d.d.) on peatland sites with a wide peat nitrogen gradient (0.79- 2.80% in the 0-10 cm layer). In the coldest region, regardless of the peat total nitrogen concentrations in the 0-10 cm surface peat layer and PK- fertilization or PK-refertilization (37 and 26 years earlier respectively), the needle nitrogen concentrations were mostly below the severe deficiency limit (N = 1.2%) and also the arginine concentrations revealed a nitrogen shortage (<0.5 mg g-1). In the middle region the mean nitrogen concentrations in the needles were clearly higher and in the PK- fertilization and PK-refertilizations (32 and 22 years earlier respectively) surpassed the slight nitrogen deficiency limit (N = 1.3%). Also the arginine concentrations surpassed the deficiency limit (0.5 mg g-1 ) in both fertilization treatments although the mean arginine concentrations were near or under the deficiency limit. In the warmest region 25-26 years after the spot fertilization the mean nitrogen concentration was 1.84% and the arginine concentration was 3.04 mg g-1 revealing a surplus of nitrogen caused by phosphorus and potassium deficiencies. The PK-fertilization given 10 years later decreased the nitrogen concentration to 1.56% and the arginine concentration to 0.58 mg g-1. In the more favourable conditions the nitrogen and arginine in the needles increased when the nitrogen in the peat increased. In conclusion, tree growth in the middle and the warmest temperature sum region would respond to PK-refertilisation above a certain total peat nitrogen level but in the coldest temperature sum region tree growth would not respond to PK-refertilization in any of the studied peat total nitrogen conditions because of nitrogen deficiency.

• Pietiläinen, The Finnish Forest Research Institute, Muhos Research Station, Kirkkosaarentie 7, FIN-91500 Muhos, Finland Sähköposti: ei.tietoa@nn.oo
• Kaunisto, Sähköposti: ei.tietoa@nn.oo

The mycorrhizal infection of the roots of four-year-old Scots pine seedlings was stud ied by analysing root ergosterol, endogenous polyamines, nitrogen, phosphorus and potassium concentrations after two years in the field.The seedlings had been planted in a 25-year-old pine plantation on an originally treeless mire representing a wide peat nitrogen gradient.Common mycorrhizal types with Scots pine, such as Cenococcum Piloderma and Boletaceae types, and a number of unidentified types were found in the roots.The roots contained quite normal or a little lower levels of ergosterol than re ported elsewhere on tree roots in mineral soil forests.After two growing seasons in the field a positive correlation (r =0.584**)was found between the root ergosterol and peat nitrogen concentrations.The root ergosterol and spermidine concentrations correlated positively.This may be due to a more abundant physical presence of the fungal tissue which contains more spermidine than the other polyamines, or it may be due to a posi tive effect of the mycorrhizal fungi on the metabolic activity of the roots.

• Sarjala, Finnish Forest Research Institute, Parkano Research Station, Kaironiementie 54, FIN-39700 Parkano, Finland Sähköposti: ei.tietoa@nn.oo
• Kaunisto, Sähköposti: ei.tietoa@nn.oo