Current issue: 56(4)
Under compilation: 57(1)
A system for measuring the net photosynthesis, transpiration and environmental factors within the canopy and ground cover vegetation is described. The system operates continuously throughout the growing season in a young Scots pine (Pinus sylvestris L.) stand. A data-logging unit controls the system and carries out the measurements on the readings of the sensors of photosynthesis, transpiration, light intensity outside the canopy, light climate inside the assimilation chambers, and dry and wet temperatures from selected points. These measurements are shown digitally and automatically punched onto paper tape.
The PDF includes a summary in Finnish.
The article presents the background of increment calculations and periodic measurements of forests, as well the historical development of increment calculations in North-America, Middle-Europe, Scandinavia and Finland. The measurements and calculations are presented for individual trees, for a forest stand and for the total resource of a normal forest stand.
The practice of increment calculations has still some problems regarding the measurements of standing and harvested trees. The article discusses some ways to overcome the problems.
Water and amount of light are the most important growth factors and the article discusses their relationship. It is knows that the more space is needed by a tree the worse the site is. The number of stems varies between tree species. Common understanding is that amount of light is decisive to self-thinning and regeneration of a stand. On a good site the adequacy of water may substitute the lack of light. However, the fertility of soil and moisture content is more important than light.
The question of the importance of light, soil fertility and water content, as well as their relationship is important when optimizing the forest management.
The PDF contains a summary in Finnish.
The study is based on the results of the soil studies by Valmari (1921) and the growth inventories of respective areas. The aim is to show the connection of soil fertility (nutrient content) and forest growth with means of correlation calculations. The examined nutrients were nitrogen, calcium and phosphorus, also the electrolyte content was studied.The results show that with increase of nitrogen content of the soil the growth of pine stand increases as well. The correlation is clearly identified. The number of birch and spruce stands is too small for systematic review. For calcium there is a similar kind of relation. With phosphorus content or amount of electrolytes the correlation with doesn’t exist. Also the loss on ignition test was conducted. The relation found is somewhat weak.