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Value of merchantable timber in Scots pine stands of different densities

Bembenek M., Karaszewski Z., Kondracki K., Łacka A., Mederski P. S., Skorupski M., Strzeliński P., Sułkowski S., Wegiel A.

Drewno : prace naukowe, doniesienia, komunikaty

2014

vol. 57, nr 192

133--142

Differences in the intensity of silvicultural treatments, as well as natural tree mort- ality, insect damage and fungal disease can eventually lead to variable stand density even on sites of the same quality. In addition, the bigger the initial stand density, the smaller the crown and trunk volume of single trees. The objective of the research was a detailed analysis of the impact of stand density on the total stand volume and value of merchantable timber. The area studied was in Drawno Forest District, north-west Poland, on sites with sandy soil conditions typical for Scots pine (Pinus sylvestris L.). The total volume of merchantable roundwood was measured on 20 sample plots (each covering an area of 0.5 ha) of which 19 were in 82-year-old stands and one in an 87-year-old stand. The stands were divided into three stand density groups (SDG), where the average number of trees growing per group was as follows: 547 (SDG I), 651 (SDG II) and 765 (SDG III). The volume of a single tree was calculated using diameter (DBH) and height measurement. A quality classification of all 6432 tree stems was carried out in accordance with the Polish Standard. Statistical analysis did not indicate that density influenced the total timber volume of the stands studied, which was recorded as an average of 323 m3∙ha-1. However, statistically significant differences in the value of merchantable timber were observed: the highest value of 100 m3 of merchantable timber was recorded in SDG I (€ 5118.87), 6 and 12% higher than in SDGs II and III (€ 4842.09 and € 4565.80, respectively). The results obtained suggest that in the final phase (the last two age classes), pine stands growing in Polish conditions should be maintained at a lower stand density.

Bilans wodny (1987-1990) zlewni krasowej potoku Sąspówka (13,6 km2) w Ojcowskim Parku Narodowym

Suliński J., Owsiak K., Sułkowski S.

Czasopismo Techniczne. Środowisko

2005

R. 102, z. 10-Ś

119--131

Sąspówka is a right-hand side tributary of the Prądnik River in the Ojców National Park. This catchment is characterized by several features which could substantially influence its water balance: the upper part of the catchment, located in a plateau, is utilized for agriculture, while he lower part consists of steep slopes, largeIy covered by forests (Fig. I, Tab. I). The topic of this paper is developing a crude water balance for the entire catchment and for its parts; upper one and lower one, the latter one treated as a difference between entire catchment and the upper part. The detailed goals of this study were: presentation of the basic features of the water balance for different parts of the catchment and comparison of the balances for the forested and non-forested parts of the catchment [8]. The climate of the study area was characterized on the basis of data from climatic stations in Kraków and in Olkusz. In both stations precipitation is usually larger the evaporation.In Kraków for 19 analyzed years oni y in 7 the precipitation was lower than the potential evaporation; the situation in Olkusz (Fig. 2) was similar [8]. During this study, the first and third year were drier than the average, while the second year was very close to mean values. AlI components of the water balance were calculated as mean monthly values for the entire catchment and for its parts - the forested and non-forested ones (Tab. 3). The water losses (evaporation form the catchment area and runoff outside the main river bed) were calculated on the basis of the balance equation. The water losses were not correlated with the evaporation estimated on the basis of measurements conducted with the Piche's evaporimeter; we can assume this to be a characteristic feature of the karst regions (Fig. 4). Taking that into account, we can reasonably assume that mean monthly runoffs from the forested and non-forested parts of the catchment are not correlated (Fig. 5).Thus, the much larger runoff from the forested part of the catchment should be interpreted rather as a product of many additional water springs, located along the stream bed in the lower part of the valley and fed with the water infiltrating in the upper part of the catchment deep into the bedrock, than as a result of differences in land use between two parts of the catchment. In comparative studies on the influence of forest cover upon the amount and dynamics of water runoff from a catchment the effect of the leak tightness of the catchment upon the study results is usually underestimated. That was clearly shown in this study, conducted in a karst type catchment.