Artikkelit jotka sisältää sanan '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

Relationships between the peat nutrient concentrations and the degree of humification, the ground vegetation and the botanical composition of the peat were studied on an afforested, originally treeless mire with a wide nitrogen gradient. The afforestation was carried out in 1971 using spot sowing and spot fertilisation. A broadcast fertilisation experiment that involved six replicates with four treatments, (i) a control, (ii) PK (rock phosphate and KCl), (iii) PK+ B, Cu and (iiii) wood ash was established in 1981–82. The surface peat layers were sampled for nutrient analyses in 1995 and for peat type determinations in 1997. The ground vegetation was inventoried in 1995. In 1995, the peat total nitrogen concentration varied from 8.7 to 29.1 mg g-1 in the 0–5 cm peat layer. The total nitrogen, phosphorus and iron concentrations and the degree of humification in the peat were all positively correlated with the proportion of Carex components and with each other. The frequency of Sphagnum mosses correlated negatively but that of forest mosses positively with the peat total nitrogen concentration. Broadcast fertilisation with wood ash increased the concentrations of phosphorus, potassium, calcium, magnesium, manganese, boron, copper and zinc especially in the 0–5 cm peat layer but did not affect other peat properties or the ground vegetation.

• Hartman, Finnish Forest Research Institute, Vantaa Reseach Centre, P.O. Box 18, 01301 Vantaa Sähköposti: ei.tietoa@nn.oo
• Kaunisto, Sähköposti: ei.tietoa@nn.oo
• Silfverberg, 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

A natural property of mires is their ability to accumulate carbon and nutrients in the form of peat.Drainage and agricultural land use have changed the nutrient balance from accumulation to mobilisation.In this study, the effect of land use and hydrology on nitrogen dynamics is quantified using a GIS-based dynamic modelling approach.In the simulation, the nitrogen budget is controlled by drainage depth, land use type and fertilizer application.Denitrification is, next to harvest, the quantitatively most impor tant output pathway from peat soils with a predominant vertical water flow.Only for the wet Caricion elatae type was a net nitrogen accumulation simulated.The spatial visualisation of the nitrogen balance shows a high variability based on the heterogene ity of the peatland.Rewetting and extensivication can reduce the deficit in the nitrogen balance and lead to a slight increase of the accumulating area.These simulation results can be used in environmental planning to define a more sustainable land use in the future.

• Trepel, Royal Danish School of Pharmacy, Section of Environmental Chemistry, Universitetsparken 2, DK-2100 Copenhagen, Denmark Sähköposti: ei.tietoa@nn.oo
• Davidsson, Sähköposti: ei.tietoa@nn.oo
• Jørgensen, Sähköposti: ei.tietoa@nn.oo

The effects of fertilization and refertilization on the growth of pubescent birch (Betula pubescens) stands growing on drained peatlands in northern Finland were studied in eight field experiments. The treatments were: (i) control with no fertilization, (ii) fertilization with nitrogen (N), (iii) fertilization with phosphorus and potassium (PK), and (iv) fertilization with nitrogen, phosphorus, and potassium (NPK). The sites represented four different mesotrophic to eutrophic site types with stand median heights ranging from 7 m to 13 m. Tree growth was monitored at stand level during periods of five to eleven years following the setting up of the experiments and during periods of 4 to 7 years following the repetition of the treatments in 1985. At the end of the second period, sun-exposed leaves were sampled from two stands in August 1990 for the purpose of conducting foliar nutrient analyses. The first-time fertilization treatments did not affect tree growth on any of the site types. Following the repetition of the treatments, the stands responded positively to NPK or PK fertilization on all site types except on the shallow-peated herb-rich peatland forest. There was no response to mere N-fertilization on any of the site types. The growth responses observed were weaker than those reported for Scots pine in similar climatic conditions. Key words: Betula pubescens, foliar nutrients, growth responses, nitrogen, peatland, phosphorus, potassium

• Penttilä, The Finnish Forest Research Institute, Rovaniemi Research Station, P.O.Box 16, FIN-96301 Rovaniemi, Finland Sähköposti: ei.tietoa@nn.oo
• Moilanen, Sähköposti: ei.tietoa@nn.oo

Abstract: The stand-level responses to fertilization and refertilization were studied in seven factorial field experiments established in 1974-1976. The factors were nitrogen fertilization (N) and phosphorus-potassium fertilization (PK). The factorial treatments were applied at two levels: (i) control and (ii) fertilized with a dosage following the currently used Finnish forest fertilization guide-lines. The spruce-dominated stands were selected from areas drained according to normal forestry practises between 1932 and 1969. The sites covered fairly well the trophic variation that occurs on spruce-dominated peatlands in the mid-boreal zone in Finland. Tree growth was monitored during two periods of five to seven years. The second period followed the refertilization in 1985. At the end of the second period, one-year-old sun-exposed needles were sampled from the four southernmost stands for nutrient analyses. The effects of fertilization on tree growth were generally fairly weak and insignificant, especially during the first study period. After refertilization, the effect of N was positive in three stands on mesotrophic sites. The foliar nutrient analyses of unfertilized spruces showed low concentrations of N, P and Cu. PK-fertilization increased foliar P concentrations and, in some cases, also K concentrations. Since the PK-fertilizer included some borate, it also increased foliar B concentrations. N-fertilization did not affect foliar N, P or K concentrations but it decreased foliar concentrations of Ca, Zn, and B in some cases. Both the growth responses and the foliar nutrient analyses indicated that nitrogen was the most deficient macro-nutrient. Key words: foliar nutrients, growth responses, mires, nitrogen, phosphorus, Picea abies, potassium

• Moilanen, The Finnish Forest Research Institute, Muhos Research Station, Kirkkosaarentie, FIN-91500 Muhos, Finland Sähköposti: ei.tietoa@nn.oo
• Penttilä, Sähköposti: ei.tietoa@nn.oo
• Issakainen, Sähköposti: ei.tietoa@nn.oo

The short-term effects of wood ash, PK and NPK fertilizers on total N and P contents of various mosses at an old drainage area in eastern Finland are studied. Total N contents increased after NPK treatment and total P contents increased after treatments that contained phosphorus (NPK, PK, wood ash). N contents of some mosses also increased after treatments which did not contain any nitrogen (PK and wood ash). On these plots drainage and obviously the fertilizer treatment fastened the decomposition rate of the peat and at the same time the mobilization of the nutrients. On the control plots (no fertilization) the N contents of the mosses did not differ statistically between the years in either of the study sites. The P contents of some mosses decreased on the control plots of the spruce swamp. One reason for this was apparently the level of the ground water, which did not lower so much in the spruce swamp than in the pine mire, and so the mobilization of the nutrients remained smaller. The observed nutrient contents of the peat mosses were much smaller than those of the forest mosses and the nutrient contents were also smaller at pine mire than at spruce swamp. Keywords: bryophytes, fertilization, drained peatlands, nitrogen, phosphorus.

• Jäppinen, University of Joensuu. Department of Biology. P.O. Box 111, SF-80101 Joensuu, Finland Sähköposti: ei.tietoa@nn.oo