Artikkelit jotka sisältää sanan 'Pinus sylvestris'

Should the frequency of drought increase in boreal forests due to climate change, seedlings planted in prepared peat mounds could become more susceptible to soil desiccation. The resistance of Scots pine (Pinus sylvestris L.) seedlings to drought will thus be a key factor in the regeneration success of pine-dominated, forestry-drained peatlands. In this study, we evaluated the physiological, metabolic, and morphological responses of year-old seedlings gradually exposed to extreme drought in highly decomposed Sphagnum-Carex peat blocks. Drought clearly suppressed root and shoot growth as well as fractional colonization of ectomycorrhizal fungi. Sustained declines in photochemical efficiency (Fv/Fm) of previous-year and current-year needles did not occur until the volumetric soil water content had dropped to 30% and 10%, respectively. Polyamine analysis revealed that new needles are preferred in protecting the different parts of the seedlings against drought stress. Despite growth losses, the maintenance of rather high photochemical efficiency in current-year needles under severe water stress would appear to indicate a potential for seedling recovery if water availability in the peat improved. Given the high tolerance exhibited by Scots pine seedlings, death by drought seems a lesser concern.

• Pearson, Finnish Forest Research Institute, Parkano Research Unit, Kaironiementie 15, FI-39700 Parkano, Finland Sähköposti: ei.tietoa@nn.oo
• Saarinen, Sähköposti: ei.tietoa@nn.oo
• Heiskanen, Sähköposti: ei.tietoa@nn.oo
• Sarjala, Sähköposti: ei.tietoa@nn.oo
• Laine, Sähköposti: ei.tietoa@nn.oo

The effects of potassium (K) fertilisation on the nutrient status and growth of Scots pine (Pinus sylvestris L.) stands on drained peatlands were studied on three field experiments in northern central Finland. The Scots pine stands were at a sapling or pole stage with a dominant height of 3–8 m when the experiments were set up. The stands differed from each other in their nutritional status, for example, the foliar K concentration varied considerably between the experiments. The experiments were fertilised with potassium chloride, rock phosphate (P 42kg ha-1) and urea (N 46kg ha-1) between 1979 and 1980. The potassium doses in terms of elemental K, were 50, 100, 200 and 400kg ha-1. The foliar samples were taken three times during the study period: 7–9 years, 14–15 years and 19–20 years after fertilisation. The stand measurements were done 19–22 years after the fertilisation. The rate and magnitude of stand response due to fertilisation depended essentially on the nutritional status of the trees. The strongest effect of PK-fertilisation was obtained on a nitrogen-rich peatland, where the stands suffered from severe phosphorus and potassium deficiencies (foliar P concentration < 1.2 mg g-1, K concentration < 3.5 mg g-1). During the study period, the annual stand volume growth on fertilised plots ranged from 3.9 to 5.4 m3 ha-1 a-1, and that of the unfertilised plots was 0.78 m3 ha-1 a-1. In other sites, where the lack of phosphorus and potassium was not so drastic, nor did the trees suffer from shortage of nitrogen, the effect of PK-treatment on tree growth was weak or almost non-existent. The foliar K concentrations rose with the amount of potassium chloride applied. The fertilisation effect of the dose of 100kg K ha-1 lasted 15–20 years, after which the foliar K concentration dropped close to the deficiency limit. The effect of the larger doses (200–400kg K ha-1) on the needle K concentration was more pronounced and still visible at the end of the study period. However, the stand growth responses gained with larger potassium applications were not essentially greater than those with the 100 kg ha-1 dose.

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

The development, structure, production and fertilisation of planted black spruce (Picea mariana (Mill.) B.S.P) and Scots pine (Pinus sylvestris L.) stands growing on a drained, originally treeless Sphagnum papillosum fen (LkKaN) in Central Finland up to the age of 30 years were studied. For black spruce the stem number was 2250 stems ha–1, dominant height was ca 7.1 m, the mean stand volume 26 m3 ha–1, the annual mean volume increment 1.5 m3 ha–1 and the total mortality based on stem number was 21%. For Scots pine the comparable characteristics were 1015 stems ha–1, 10.4 m, 45 m3 ha-1 , 3.3 m3 ha-1 and 59% respectively. Fertilisation had no apparent impact on the stand characteristics. About 63% of the planted black spruce individuals had at least one vegetatively generated layer. High number of layers seemed to have a negative effect on dominant parent tree growth. It is concluded that growth and yield of black spruce are generally not competitive in operational forestry in Finland. However, black spruce could be used as an alternative tree species in treeless areas that resist afforestation, and it might also be cultivated for decorative purposes.

• Sarkkola, Department of Forest Ecology, P. O. Box 27, Fin-00014 University of Helsinki Sähköposti: ei.tietoa@nn.oo
• Päivänen, Sähköposti: ei.tietoa@nn.oo

The effects of refertilisation and growing density on the soil and tree nutrition, root penetration and growth of Scots pine stands were studied in a cutaway peatland area with deep peat layers. The fertilisation treatments were control, N1975+PKB1985 and PK1975+PKB1996 refertilisations and those of the growing density <1 300, 1 654 and 1 954 trees ha-1. The maximum root penetration varied between 26 and 34 cm independently of the treatments. The N/P ratios in pine needles were quite high even on the refertilised plots (11.6-15.7). The duration of P fertilisation seems to be shorter (about 15 years) on cutaway peatlands with deep peat layers than on drained peatland forests. The greatest yield without natural removal (239 m3 ha-1, on an average) in 35-years-old stands was measured on plots, which had the highest growing density and had been repeatedly fertilised with PK. The results show that quite a high yield of Scots pine can be reached on cutaway peatlands. However, pine has to be fertilised with PK at the afforestation stage and at least once later if the remaining peat layer is 40-60 cm, and possibly several broadcast fertilisations are needed on peat layers deeper than 60 cm. It seems that growing tree stands on cutaway peatlands in higher densities than in conventional forestry may improve nutrient cycling in stands and hence decrease leaching of nutrients from the site.

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

This study aimed at finding out the effects of maintaining ditch systems by ditch cleaning and complementary ditching on volume growth of drained Scots pine (Pinus sylvestris L.) stands. Volume growth during the first ten post-treatment years was increased by 0.16 m3 ha-1 a-1 after ditch cleaning, 0.36 m3 ha-1 a-1 after complementary ditching, and 0.48 m3 ha-1 a-1 after the combined treatment. The average growth reactions during the second five-year period were considerably higher than during the first one. No drastic reductions in stand growth, however, occurred in the untreated plots during the post-treatment period of ten years.

• Lauhanen, The Finnish Forest Research Institute, Kaironiementie 54, FIN-39700 Parkano, Finland Sähköposti: ei.tietoa@nn.oo
• Ahti, 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

The effect of thinning on the groundwater table level was studied in four stands of Scots pine (Pinus sylvestris) on drained peatlands in northern Finland. Four thinning intensities (0-50% removal of the initial stocking), with three replications arranged using a randomized block design, were used in each experiment. If found to be in an unsatisfactory condition, the ditch networks were repaired at the time of thinning. Data from nine groundwater wells on each plot were used to determine the average depth of the groundwater table. The wells were monitored at two-week intervals during the latter parts of the growing seasons in 1991-1993. The mean groundwater table depth was used as the dependent variable in ANOVA with repeated measurements. In most cases, the groundwater table depth was lowest in the control plots, but significant differences between the treatments were found only in 1993 in two experiments. It was concluded that thinning caused no rise, or only a slight rise, in the groundwater table level. Keywords: Forest drainage, groundwater table, Pinus sylvestris, thinning

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

The post-drainage growth of a simulated model stand according to different thinning methods was predicted for 84 years by spatial single-tree growth models. In thinnings, the post-thinning stand density varied as a function of the distance of the ditch. The best yield and income were obtained by leaving the stand near ditches and extraction road midway between ditches denser than elsewhere. Keywords: growth model, Pinus sylvestris, stand management

• Miina, University of Joensuu, Faculty of Forestry, P.O.Box 111, FIN-80101 Joensuu, Finland Sähköposti: ei.tietoa@nn.oo
• Pukkala, Sähköposti: ei.tietoa@nn.oo

Liming (with applications of 1 000 to 8 000 kg ha1) had no long-term (1929-1985) effect on the growth of Scots pine on drained oligotrophic peatlands. Liming plus NPK fertilization had a variable effect on the growth of the stands. The same treatment could result in a very different response in different experimental areas. Both liming alone and liming plus NPK fertilization increased the calcium, magnesium and nitrogen contents of peat and decreased the C/N ratio and acidity. Liming plus fertilization decreased needle boron and manganese and increased calcium and nitrogen concentrations. The results of peat and needle analysis indicated that the changes in nitrogen availability to trees caused by liming have not been sufficient enough to affect tree growth. It was also concluded that boron deficiency was the main reason for the lowered yield. Key words: fertilization, needle nutrients, peat nutrients, Pinus sylvestris, tree growth

• Nieminen, The Finnish Forest Research Institute, P.O. Box 18, FIN-01301 Vantaa, Finland Sähköposti: ei.tietoa@nn.oo
• Pätilä, Sähköposti: ei.tietoa@nn.oo

Variation in nutrient concentrations in Scots pine needles in relation to crown position and needle age was examined at two drained peatland fertilization experiments. Samples were taken from plots which had received NPK fertilizer and from sites which had received only P fertilizer and are now suffering from potassium and phosphorus deficiency. In the NPK fertilized plots, potassium concentrations were the lowest in the needles of the uppermost branchlet and increased down the crown. On plots showing potassium deficiency the situation was the opposite. In both experiments phophorus, magnesium, iron, zinc, and boron concentrations decreased and calcium concentrations increased down the crown but in potassium and phosphorus deficient trees calcium and manganese concentrations decreased down the crown. In both experiments phosphorus, potassium, magnesium and boron concentrations decreased with needle age while calcium, iron and manganese concentrations increased. Zinc concentrations increased in NPK fertilized trees but decreased in potassium and phosphorus deficiency trees. Keywords: Crown position, needle analysis, nutrient variation, Pinus sylvestris

• Kolari, The Finnish Forest Research Institute, Box 18, FIN-0I301 Vantaa Sähköposti: ei.tietoa@nn.oo

Total fine root biomass was 397 g/m2 at an afforested and fertilized tall sedge fen (VSN), and 529 g/m2 at a tall sedge pine fen (VSR). The studied sites were located on the Lakkasuo mire complex in central Finland. The greater biomass on the VSR site could be a result of its lower nutrient status compared to that of the fertilized VSN site. Total root production during May-September 1991 was 178 g/m2 at the VSN site and 242 g/m2 at the VSR site when all significant increments in the living and dead root biomasses were summed up. Almost half of the fine root biomass was renewed during the summer. Keywords: Biomass, drainage, ground vegetation, necromass, Pinus sylvestris, production

• Finér, Finnish Forest Research Institute, Joensuu Research Station, P.O. Box 68, FIN-80101 Joensuu, Finland Sähköposti: ei.tietoa@nn.oo
• Laine, Sähköposti: ei.tietoa@nn.oo
• Halko, Sähköposti: ei.tietoa@nn.oo

This paper is based on four experiments established in 1960-1969. There were four sources of potassium: potassium chloride, double salt of potassium and magnesium sulphates, cement potassium and potassium sulphate. The application rates of fertilizer potassium varied from 0 to 664 kg/ha as pure element. Nitrogen and phosphorus or phosphorus alone were also given at the beginning. The experiments were inventoried in 1988. The peat potassium amounts were independent of the application rate. On the other hand, the foliar potassium concentrations were the higher the higher the application rate. Yet, the effect of currently used potassium fertilizer rate, (about 80 kg/ha of K), on the foliar potassium concentrations did not significantly differ from the effect of the double rate. Fertilization increased the basal area growth for 8-22 years, after which the growth started to decline. The reason can at least partly be attributed to the shortage of potassium. The growth response was independent of the potassium source and rate on the potassium fertilized plots. Key words: Foliar nutrients, peatland, peat nutrients, Pinus sylvestris

• Kaunisto, The Finnish Forest Research Institute, Parkano Research Station, SF-39700 Parkano, Finland Sähköposti: ei.tietoa@nn.oo

NPK fertilization increased volume growth by 6.3 m3 ha-1 and PK fertilization by 4.3 m3 ha-1 within six years after nutrient application. The results indicate that dominant and co-dominant trees respond to fertilization better than suppressed ones, and that the trees close to the ditches benefit almost as much from fertilization as those in the middle of the strip. NPK fertilization also increased the mortality of the intermediate trees. Keywords: bog, drainage, increment, Pinus sylvestris, tree class

• Finér, Finnish Forest Research Institute, Joensuu Research Station, P. O. Box 68, SF-80101 Joensuu, Finland Sähköposti: ei.tietoa@nn.oo