Articles by P. Kokkonen

Soil frost from the winter 1941-1942 was of a special form. To create such a strong soil frost there need to be capillary soil form and long period of permanent and intense cold, meaning minus temperatures.  The frost layer was thicker than normally.

Such a frost causes many problems on the fields and roads when the soil rises because of the frost and then falls unevenly back when the frost melts.

• Kokkonen, E-mail: pk@mm.unknown

The shape of land lots formed in parceling of land has been affected by many variables. It is an important economic factor when the land is used in forestry or agriculture. The report concentrates on the larger farms with relatively large forest holdings. In the general parceling of the land that started in the middle of 1700s, the allotted plots were often long and narrow, and the width of the plot could be 20‒50 meters. Later these farms may have been further parceled.

Narrow plots are difficult to manage from the forestry point of view. For example, it is not possible to build a forest road in the plot, and wood harvesting is difficult. To use natural regeneration for a specific tree species is impossible, because the seed trees in the adjacent plot are so near. When the boundaries are long and the properties narrow, there is bigger risk for felling trees on the land of the neighbour. The optimal form for a plot is rectangle which is 3‒6 times longer than its width. Local examples of parceling and the effects of the shape of the plots are given in the article.

The PDF includes a summary in German.

• Kokkonen, E-mail: pk@mm.unknown

Knowledge on the roots systems and their properties is needed when for example assessing the wintering properties of a plant. The article presents the studies on the roots and their functions made with rye, wheat, oat and barley.

The data has been collected during the whole growing season. The experiments took place in the green houses of the University of Helsinki and on the experiment field in Tikkurila, some kilometres north from Helsinki.

The roots of cultivable crop can be divided according their function, state of development, structure and position in the root system into four classes. The classes are sprouting roots, nutriment roots, nutriment-support roots and support roots.

The PDF contains a summary in Finnish. 

• Kokkonen, E-mail: pk@mm.unknown

The article presents the observations made on peatland “Savonneva” in summer 1929 in commune Pulkkila, north-west Finland. The study concentrates on the relationship between groundwater level and growth of trees. The areas was first ditched in 1894, when a main ditch and a side ditch were dug. The ditches were repaired several times, last time a year before the study took place.    

Parts of the area has been taken for agricultural purposes, and other areas have been naturally afforested. The size and abundance of trees varies strongly because the drainage of the area has been uneven. Closer to the main ditch the forest grows better than further away. There is a clear line between the afforested and open areas.

It seems that the tree growth decreases faster with certain groundwater levels than if the groundwater level is deeper.  

The volume 34 of Acta Forestalia Fennica is a jubileum publication of professor Aimo Kaarlo Cajander.

• Kokkonen, E-mail: pk@mm.unknown

In attempts to improve the autumn cereals, wheat and rye, hibernation plays an essential role. Those varieties that hibernate well should be marketed and others rejected. Concerning roots, it seems that varieties that hibernate well have more extent root system than those hibernating poorly.

Four varieties of rye were chosen for experiments, two that knowingly hibernate well and two that don’t. The experiments were grown in the Botanical gardens of the university and at the same time in experiment field in Tikkurila.

The results proof that plant hibernating well have more extensible roots than others and hence they survive better in frosting soil that extents.

The PDF contains a summary in English and in Finnish.

• Kokkonen, E-mail: pk@mm.unknown

The article presents some basic elements of soil frost and its occurrence.  The data contains observations from different regions and soil types in Finland. Different forms of soil frost and factors affecting its formulation are discussed. 

• Kokkonen, E-mail: pk@mm.unknown

Approximately 320,000 hectares of peatlands and paludified lands had been drained for agriculture and forestry purposes in Finland by 1920. The ditch network was not optimal in the early drained areas, and the condition of the ditches declined over time. In this study, the condition of drainage system, and the natural processes that affect them, was inspected in 18 drained peatlands.

Several processes can reduce of the size of the ditches. The process of crumbling of soil in the sides of the diches can last up to three years after the draining. Erosion of the main drains, caused by water flow can, however, continue longer. The ditches also sink when the peat dries. Soil frost can affect the ditches, but as the vegetation grows its effect gradually decreases. The vegetation that grows in the ditches may finally block the ditch completely.

The PDF includes a summary in English.

• Kokkonen, E-mail: pk@mm.unknown

The data has been collected during 1919 and 1920 in different region of Finland. The studied peatlands varied from fuscum pine swamps to pine swamps and partly to better sedge pine swamps.

The study presents five different forms of root systems. The root growth of pine on peatlands seems to vary strongly from the root form on mineral soils. On the peatlands, where the ground water near to soil cover is, can the roots grow only near the soil surface where the conditions are suitable. For the pine typical tap root is in most cases absent or grows along the soil surface. Also the frost heaving, snow and characteristics of peat affect the root system.   

• Kokkonen, E-mail: pk@mm.unknown