Current issue: 53(2)
Under compilation: 53(3)
In a natural state growing closed forest the amount of timber grows yearly. However, in the same time the timber volume also decreases when part of the trees die in the competition for light and other growth factors.
There are many interactive functions and characteristic that influence the growth and drain in a stand. These can be illustrated as mathematical models. The article discusses a set of models.
The volume 34 of Acta Forestalia Fennica is a jubileum publication of professor Aimo Kaarlo Cajander.
The article is a presentation given by the author on occasion of visit from Austrian timber industry and foresters (August 17th 1923), and again for the German visitors (August 20th 1923) in Punkaharju, Finland. The speech deals with the question of the overuse of Finnish forest compared to their growth. The developments of slash-and-burn-culture and forest inventories are described. The results of the inventories show, though still in preliminary state, that there is no nationwide overuse in total, though there are some locations where the felling are bigger than growth.
This study estimates the supply of soil water required for the annual and total production of energy material by the biomass of 32-year-old plantation of red pine, Pinus resinosa Ait. in Wisconsin, the United States.
The supply of transpiration water was determined as the sum of summer precipitation, winter stored water, and condensed vapor, minus gravitational discharge and evaporation of intercepted rainfall. On the average, the 1,20 m root zone of coarse sandy soils of central Wisconsin receives 2,750 M.T. of water per hectare. During the 32nd year of plantation growth, the increment biomass, including 43% of merchantable timber, was 10,100 kg/ha, or 162 x 105 kcal/g. At this time of the culminating growth, the production of 1 kg of wood material consumed 272 kg of water. The corresponding transpiration coefficient 0,37% is near the maximum for the ecosystem of hard pines – sandy soils of glacial outwash with field capacity between 7 and 9%. On the weight basis, the annual leaf fall constituted 32% of the biomass and over 80% of merchantable timber.
The entire supply of water of 96,000 M.T./ha produces in 32 years 211,112 kg of total dry matter at a rate of 1 kg of wood per 455 kg of water, with corresponding transpiration coefficient of 0,22%. The evapogravitational losses during the early stages of the stand’s growth decreased the water utilization efficiency of trees about 40%.
The information obtained permitted to outline several hydrological relationships pertinent to forest culture, namely: maximum rate of forest growth as delineated by the supply of available transpiration water; content of available moisture in soils of high tension capacity; contribution to soil water rendered by natural subirrigation and condensation of athmospehric vapor; growth depressing effect of weeds.
The PDF includes a summary in Finnish.
Silva Fennica issue 52 includes presentations held in professional development courses, arranged for foresters working in public administration in 1938. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service.
This presentation describes different methods of assessing tree growth.