Evaluation of bark volume of four tree species in Latvia
2015
Liepins, J., Latvian State Forest Research Inst. Silava, Salaspils (Latvia);Latvia Univ. of Agriculture, Jelgava (Latvia) | Liepins, K., Latvian State Forest Research Inst. Silava, Salaspils (Latvia)
The objective of this study is to elaborate the mathematical model describing the bark proportion (BP) in stems of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies [L.] Karst), silver birch (Betula pendula Roth.) and aspen (Populus tremula L.), as well as to analyze the vertical variation of the BP for the aforementioned species. The study material consists of data of 372 sample trees sampled in three regions of Latvia – Western (Kurzeme), Eastern (Latgale) and North-eastern (Vidzeme) during the years 2011 – 2014. The BP for each tree was calculated as a difference between the under-bark and over-bark stem volume. In this study, we compared the performance of three power regression models in predicting of BP using breast height diameter (DBH), tree height (H) and total volume (TV) as independent variables. The best fit to data was achieved by using tree height for the prediction of BP. Our results confirm that the highest proportion of the bark is at the upper part of the stem (relative height 95%) for all trees species. Pine stems have a lower BP of up to 30% relative height comparing to other species, while the spruce has the lowest bark percentage at the stem base relative to other tested species There were no significant differences found in BP among the stands from different regions for all studied species, indicating no need for derivation of separate equations for each region and ascertaining the possibility of use of the average BP values for the whole country.
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