Articles containing the keyword 'peittävyys'

The study deals with the distribution of above-ground biomass of Vaccinium myrtillus L. along the vegetation continuum segregated by using phytosociological classification method composite clustering. The qualitative characteristics of forest sites corresponding to different vegetational clusters were defined on the basis of indirect gradient analysis of vegetation data and description of tree stand properties in stands in 160 sample areas in Southern Finland.

Six vegetation types differing from each other mainly in abundance of the most constant and dominant plant species were formed. Sample areas with rich grass-herb vegetation, as well as sample areas representing comparatively dry, barren site type were clearly separated from other groups of sample areas. Stand characteristics, particularly the proportional distribution of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) seems to be another important factor affecting the vegetation composition.

The lowest biomass values of blueberry were connected with herb-rich vegetation and shady spruce-dominated stands. Comparatively low values were connected to also other spruce-dominated sample areas. Pine-dominant or mixed pine-spruce stands the biomass values were significantly higher. Even if the site quality is essentially equal, the abundance relationships between Vaccinium myrtillus and other components of the ground vegetation may vary in wide ranges and cause difficulties in practical site classification.

The PDF includes a summary in English.

• Kuusipalo, E-mail: jk@mm.unknown

A mature Scots pine (Pinus sylvestris L.) stand growing on a site of the Vaccinium type in Southern Finland was fertilized with nitrogen-rich NPK fertilizer at a level of 150 kg pure nitrogen per hectare. The sample plots were also irrigated during four growing seasons. The total amount of irrigation during this period was 1,200 mm. Fertilization alone increased the coverage of grasses and dwarf shrubs. The culmination of the increase occurred during the second growing season after the start of the treatment. The rapid effect of irrigation on the coverage of ground vegetation was not so strong as that of fertilization. It was concluded on the basis of the developed growth model that the coverage of dwarf shrubs, especially Calluna vulgaris, was, however, increased with the fertilization treatment for a prolonged period. Fertilization and irrigation had no visible effect on the coverage of lichens and mosses.

The PDF includes a summary in Finnish.

• Mälkönen, E-mail: em@mm.unknown
• Aro-Heinilä, E-mail: va@mm.unknown
• Kellomäki, E-mail: sk@mm.unknown

The study deals with the relationship between biomass and coverage in ground vegetation of Vaccinium and Calluna forest types. The results show that the biomass of the field layer on both forest types can predict satisfactorily in both coverage values of some the most important species and groups of species. Their total height per plot was used as independent variables. The explaining power of the models constructed for Vaccinium type increased to approximately 57% and for the Calluna type to approximately 74% of the total variation in the amount of dry matter. When the biomass of the bottom layer was predicted using the same kind of variables, the explaining power for the Vaccinium type increased to approximately 35% of the total variation and for the Calluna type approximately 53% of the total variation in the amounts of dry matter. The models for field layer of both Vaccinium and Calluna types were quite well suited for describing the test material. In the case of the bottom layer, the constructed models were not suitable for describing the test material.

The PDF includes a summary in English.

• Kellomäki, E-mail: sk@mm.unknown

The possibilities of using results of coverage analyses for estimating the dry matter content of the ground vegetation has been examined in this study. The material covers 150 sample areas, 400 m² large, which represent ground vegetation of Myrtillus type in the final succession stage. When the material was subjected to linear regression analysis, the amount of dry matter in the field and ground layer has been used as dependant variables and the results of the coverage analysis as the independent variable.

The study shows that it is possible to predict satisfactorily the dry matter content of the ground vegetation by grouping the coverage, according to the coverage weight, into parts of equal size and the using them as independent explaining variables. In particular, the value of the prediction equation for the dry matter content of the field layer could be improved by using the height and density characteristics of the vegetation as explaining variables in addition to the coverage figures. Thus, slightly over 80% of the total variation of the dry matter content of the field layer could be predicted. In the case of the ground layer vegetation, the explaining power rose slightly above 70%.

The PDF includes a summary in English.

• Kellomäki, E-mail: sk@mm.unknown

The tree canopy adsorbs part of the rainfall falling on a forest, therefore only part of it reaches the soil. This report presents results concerning interception of precipitation and groundwater level in forests of varying canopy cover. The study belongs to a larger survey on afforestation of drained treeless bogs. The rainfall was measured daily in the open fields and in the adjacent forests. The forests, mainly Norway spruce (Picea abies (L.) Karst.) dominated, were divided by the canopy cover into five classes from over dense to sparsely stocked.

The results show that in a dense, tall Norway spruce stand, light rainfall can almost entirely be adsorbed by the canopy. The heavier the rainfall, the larger proportion of it reaches the ground. Only 30% of a 5 mm rainfall reaches the ground, while 80% of a 20 mm rainfall reaches the ground. Interception of precipitation decreases gradually when the density of the forest decreases. Canopy of Scots pine (Pinus sylvestris L.) and birch (Betula sp.) stands of corresponding density adsorb less rainfall than Norway spruce canopy. Groundwater level was higher in treeless areas than in areas covered with forest. Widescale clear cuttings should, therefore, be considered carefully in forest areas that are prone to become peaty.

• Lukkala, E-mail: ol@mm.unknown