Articles by Jukka Laine

The influence of different fertilization treatments and ditch spacings on the height growth of young Scots pine (Pinus sylvestris L.) seedling stands growing under various climatic regimes were determined. Comparisons were made between naturally regenerated and planted seedling stands. The effective temperature sum had a stronger effect on the height growth of planted seedlings, and in Northern Finland the planted seedlings seemed to be influenced to a greater degree by the adverse climatic conditions. The heavier the dose of fertilizer that had been applied, the greater the difference in growth caused by macroclimate. A considerably larger proportion of natural seedlings were located on hummocks compared with that of planted seedlings, irrespective of the region. On plots with wider ditch spacings, seedlings growing on hummocks were superior in height growth to those on flat surfaces.

The PDF includes an abstract in Finnish.

• Miyazava, E-mail: tm@mm.unknown
• Laine, E-mail: jl@mm.unknown

The effect of drainage on structure of tree stands is analysed by comparing the average structural characteristics (e.g. diameter distribution) of stands in the data for different drainage age classes and selected site types. The material consists of ca. 4,400 relascope sample plots, which are part of a large drainage area inventory project. The uneven-aged structure of the virgin peatland forest is preserved for several decades after drainage. This is enhanced by the post-drainage increase of small-diameter trees, especially birch. The number of trees per hectare increased during a period of ca. 30 years and levelled off thereafter. The increase in the number of saw log stems is clearly related to the fertility of the site and its geographical location.

The PDF includes a summary in English.

• Hökkä, E-mail: hh@mm.unknown
• Laine, E-mail: jl@mm.unknown

This is the latest report in a series of publications from an on-going investigation which is concerned with the influence of different fertilization treatments and ditch spacings on the growth of Scots pine (Pinus sylvestris L.) seedlings and transplants growing on nutrient drained poor bogs in different parts of Finland. This paper concentrates on duration of the growth response to NPK-fertilization on the experimental plots. The experiment was established and the treatments performed in 1965–66.

The results show that climate, expressed as effective temperature sum (dd°C, threshold +5°C) has a clear influence on the duration of the fertilization effect. In Southern Finland (>1,200 dd°C), the duration was at least 15 years. In Central Finland (1,200–1,000 dd°C), it appears to be almost 10 years, and in Northern Finland (<1,000 dd°C), slightly shorter. The amount of fertilizer applied clearly influenced the duration of the fertilization effect. The dosage of 500 kg/ha (N 14, P 7.8, K 8.3 per cent) had, on average, a shorter duration than the greater dosages of 1,000 and 1,500 kg/ha. However, there was no clear difference between the latter two dosages.

The PDF includes a summary in Finnish.

• Heikurainen, E-mail: lh@mm.unknown
• Laine, E-mail: jl@mm.unknown

Transects from upland to peatland sites were laid out so as to encounter a wide range of nutritional and hydrological conditions and volumetric soil samples were taken at 20 m intervals. For organic material, in particular peats, the correlation of ignition loss with CEC and total N were clearly higher when the variables were expressed volumetrically. The volumetric expression of variables made comparison of soils with varying organic matter contents possible. In preliminary analyses of the relationships between soil variables and dominant height of the tree stand on mineral soil sites volumetric exchangeable bases, pH and C/N -ratio in the raw humus layer showed a significant correlation.

The PDF includes a summary in Finnish.

• Westman, E-mail: cw@mm.unknown
• Laine, E-mail: jl@mm.unknown
• Starr, E-mail: ms@mm.unknown

The effects of variations in the intensity of drainage and NPK fertilization on the natural regeneration and planting results and the subsequent development of seedling stands under various climatic conditions on drained nutrient poor pine bogs was investigated in a 16-year-old study.

Comparison of height development of Scots pine (Pinus sylvestris L.) stands on drained peatlands to that of pine stands growing in mineral soil sites show that in Southern Finland the most efficient forest improvement measures (10 m ditch spacing and 1,000 kg/ha NPK-fertilization) resulted in growth that corresponds a to a height index of a stand in a Vaccinium type site. Less efficient treatment (30 m ditch spacing and no fertilizer) resulted in growth corresponding the development of young stand in a Calluna type site. In Northern Finland the effect of fertilization on height growth was almost negligible. This is possibly due to a decrease in the nitrogen mobilization from south to north of Finland. Thus, it seems evident that fertilization of young Scots pine stands on nutrient poor drained peatlands can be recommended only in the southern part of the country.

The effect of ditch spacing is same in the whole country. The narrower the spacing the better the height growth. In the south planted stands thrive better than naturally regenerated stands, but the situation is reversed in the north.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown
• Laine, E-mail: jl@mm.unknown
• Lepola, E-mail: jl@mm.unknown

An extensive field-based survey was conducted to establish the distribution of site types on drained peatlands, the condition of the drainage networks, the post-drainage development of the tree stands, their structure and silvicultural condition and the corresponding requirements for operational measures. The data is based on sampling of the forest drainage undertaking during 1930–78 and consists of 1,312 km inventory transect, 6,030 relascope sample plots and 21,700 studied ditches.

Of the studied peatlands more than 60% were Scots pine (Pinus sylvestris L.) mires, slightly under 20% Norway spruce (Picea abies) mires, and under 10% each treeless mires and paludified upland forest sites. The remaining peatland area that is to be considered suitable for forest drainage according to criteria used by Heikurainen (1960) now consists mainly of spruce mires and paludified upland forest types; about 1 million ha both groups still remain undrained.

The proportion of ditches in need of ditch cleaning was estimated to be under 10% in the youngest drained areas and under 30% in the oldest. The mean tree stand volumes of the drained peatlands of different site types show the same dependence on the trophic level as in earlier studies but the volumes seem to be some 5–10% lower. These results compare favourably with those of the 7th national forest inventory.

Trends in the post-drainage development of tree stand volumes and increment are also, generally, in accordance with earlier findings but have somewhat lower values. The development of the nutrient-poor site type stands, especially in Northern Finland, seems to be significantly poorer than was earlier assumed.

The PDF includes a summary in English.

• Keltikangas, E-mail: mk@mm.unknown
• Laine, E-mail: jl@mm.unknown
• Puttonen, E-mail: pp@mm.unknown
• Seppälä, E-mail: ks@mm.unknown

An attempt was made in this study to determine which nutrients and in what amounts should be used in the fertilization of Scots pine (Pinus sylvestris L.) seedling stands on nutrient-poor open bogs in order to obtain optimum seedling growth and to minimize the risk of elk damage.

The most important nutrient to improve seedling growth in the experiments was phosphorus. Already rather small amounts produced a significant effect although the effect of higher dosages seemed to be longer lasting. After fertilization also nitrogen gave significant increase in growth. The number of seedlings damaged by elk increased the most on N-fertilized plots. Also, phosphorus increased the occurrence of elk damage, but effect seemed to be related to the better growth and more suitable size of P-fertilized seedlings. The effect of potassium on seedling growth and on occurrence of elk damage was negligible.

The PDF includes a summary in English.

• Laine, E-mail: jl@mm.unknown
• Mannerkoski, E-mail: hm@mm.unknown

The paper presents some preliminary results of a 10-year-old study the purpose of which is to determine the effect of simultaneous variations in the intensity of drainage and fertilization on the development of planted and natural seedlings on peatlands under various climatic conditions. The development of the Scots pine (Pinus sylvestris L.) seedlings appeared to be better the more intensive the degree of drainage and fertilization used. The increase in the temperature sum had a positive effect on the development of pine seedlings and decreased the mortality rate.

The best growth result was obtained with a 10 m ditch spacing and strong fertilization. As it is difficult to decrease the 10 m ditch spacing for cost reasons, it can be concluded that on such oligotrophic peatlands as were used in this experiment, only an average growth level in the seedling stands can be reached even with the most efficient forest improvement measures. Broadcast fertilization used in the experiment, at least in large doses, increases seedling mortality, as well as the coverage of the ground vegetation, particularly that of cottongrass and fireweed, and also the shrub height, thus increasing competition. It cannot be recommended for afforestation, and today spot fertilization is used. According to this experiment natural seedlings seem once they have recovered after the first years, to grow better than the planted seedlings. This was true especially in the north and in areas, where drainage was not efficient. The height and height growth of the seedlings were to a large extent dependent on the temperature sum.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown
• Laine, E-mail: jl@mm.unknown

• Pearson, Finnish Forest Research Institute, Western Finland Regional Unit, Kaironiementie 15, FI-39700 Parkano, Finland E-mail: meeri.pearson@metla.fi
• Saarinen, Finnish Forest Research Institute, Western Finland Regional Unit, Kaironiementie 15, FI-39700 Parkano, Finland E-mail: ms@nn.fi
• Minkkinen, University of Helsinki, Department of Forest Sciences, Helsinki, Finland E-mail: km@nn.fi
• Silvan, Finnish Forest Research Institute, Western Finland Regional Unit, Kaironiementie 15, FI-39700 Parkano, Finland E-mail: ns@nn.fi
• Laine, Finnish Forest Research Institute, Western Finland Regional Unit, Kaironiementie 15, FI-39700 Parkano, Finland E-mail: jl@nn.fi

• Laiho, University of Helsinki, Department of Forest Ecology, FI-00014 University of Helsinki, Finland E-mail: raija.laiho@helsinki.fi
• Sarkkola, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: ss@nn.fi
• Kaunisto, Finnish Forest Research Institute, Parkano Research Unit, Kaironiementie 54, FI-39700 Parkano, Finland E-mail: sk@nn.fi
• Laine, Finnish Forest Research Institute, Parkano Research Unit, Kaironiementie 54, FI-39700 Parkano, Finland E-mail: jl@nn.fi
• Minkkinen, University of Helsinki, Department of Forest Ecology, FI-00014 University of Helsinki, Finland E-mail: km@nn.fi

• Laiho, Univ. of Helsinki, Dept. of Forest Ecology, Peatland Ecology Group, P.O. Box 27, FIN-00014 University of Helsinki, Finland E-mail: raija.laiho@helsinki.fi
• Penttilä, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: tp@nn.fi
• Laine, Univ. of Helsinki, Dept. of Forest Ecology, Peatland Ecology Group, P.O. Box 27, FIN-00014 University of Helsinki, Finland E-mail: jl@nn.fi

• Minkkinen, University of Helsinki, Department of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland E-mail: kari.minkkinen@helsinki.fi
• Laine, University of Helsinki, Department of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland E-mail: jl@nn.fi
• Hökkä, Finnish Forest Research Institute, Rovaniemi Research Station, P.O. Box 16, FIN-96301 Rovaniemi, Finland E-mail: hh@nn.fi