Arkadiusz Bruchwald

A growth model for European larch (Larix decidua Mill.) based on stand characteristics

Model wzrostu dla modrzewia europejskiego (Larix decidua Mill.) wykorzystujący cechy taksacyjne drzewostanu A growth model for European larch (Larix decidua Mill.) based on stand characteristics Data from each forest stand in all the Forest Districts in Poland (about 2.5 million stands) are available in the State Forests Information System (SILP). These data can be used to predict the development of timber resources and to drive growth models that determine the possibility of harvesting timber in pre-final and final felling. The Polish growth models used are individual-tree growth models consisting of four main algorithms: initial (W), thinning (T), tree mortality (S) and incremental (P). The model consists of several variants, differing only in their initial algorithm. The aim of this study is to describe an algorithm for one of the growth model variants for larch stands. The growth model variant presented employs the following characteristics of a stand as input data: mean age (W), average diameter breast height (Dg), average height (Hg), and stocking density (Zad). These data are used to generate the distribution of diameter breast heights of trees and assign an appropriate height to each tree. This enables the other growth model algorithms to subsequently be used to predict the development of larch timber resources. In Poland, growth models have been built for the following trees species: pine, spruce, fir, oak, beech, alder and birch. The growth model for larch stands completes the list and opens new research perspectives. Linking this model with those built for other tree species will lead to the development of a model for mixed stands and then for uneven-aged stands.

Model of development of terminal shoot and its branching of mature hair birch (Betula pubescens Ehrh.)

Model rozwoju pędu wierzchołkowego i jego ugałęzienia u dojrzałej brzozy omszonej (Betula pubescens Ehrh.) Model of development of terminal shoot and its branching of mature hair birch (Betula pubescens Ehrh.) Preparation of the model of the terminal shoot development and its branching in mature hair birch based on the growth analysis and branching of the terminal bud, including relationships between different features, was the goal of this paper. In order to accomplish this goal, the following questions have had to be answered: from which auxiliary buds of the principal shoot epicormic shoots will grow, which of the epicormic shoots have the highest survival rate, which of auxiliary buds stay dormant, what is the number of epicormic shoots growing on the principal shoot? 310 annual increments of terminal shoots taken from 31 monocultures of hair birch stands, aging from 26 to 112 years, were examined as empiric material. The length of the principal shoot oscillated between 1-67 cm (22 cm in average) and was negatively (but not very strongly) correlated with the age of a tree (r=0,264). The annual principal shoot was built, in average, of 10 internodes (3-20). Between the number of internodes and the length of a shoot a clear relationship was found (r=0,826), the longer shoot consisted of a larger number of internodes. The average length of the internode of the principal shoot was 2,8 cm (0,3-5,5 cm) and was correlated with the length this shoot (r=0,717); longer shoots also presented longer internodes. In average 3,3 (0-14) epicormic shoots grew on the principal shoot. The highest number of epicormic shoots was found in 1998. The least number (skipping syleptic shoots occurred in 2000 - the year of measurement) was noted in 1996 and resulted from advanced natural process of drying of epicormic shoots. The strong relationship between the number of epicormic shoots and the number of internodes of the principal shoot was found (r=0,853). The largest probability of growing out of an epicormic shoot was in the case of the highest situated internode and the smallest probability was at the lowest one. The probability of the occurrence of the epicormic shoot was related to the length of the principal shoot and thus with the number of its internodes. The probability of mortality or damage of the principle shoot was related to the number of its internodes, too. The probability of dormancy of an auxiliary bud lowered with the distance of an internode from the base of a shoot.

The method of determining risk of wind damage to tree stands.

Metoda określania ryzyka uszkodzenia drzewostanu przez wiatr The method of determining risk of wind damage to tree stands The project has developed models of damage risk to tree stands by wind. The models take into consideration the following groups of factors: varied and constant stand characteristics, location of forest district representing location of stand within country regions, where damages occurred in the past. Five variable stand characteristics were taken into account, including average height, age, species composition, average tree taper (or more precisely - its inverse), and stand density. The average tree height plays the most important role in evaluation of risk - high tree stands have the biggest risk of damage by wind. The constant stand characteristics included only forest site type, but further research should also consider other factors, such as land relief. The coefficients for the risk models were obtained from the data received from multiple forest districts of Poland, especially those, where stands were damaged by the Kyrill storm in 2007 (Regional Directorates of the State Forests in Wrocław and Katowice). The risk models give the basis for the method presented in this paper. The work also uses information from the database of the Informatics System of the State Forests. Each stand is assigned the damage risk on the scale from 0 to 3. The higher risk value shows higher probability of damage to tree stand in case of strong wind occurrence. The models of risk of wind damage to tree stands require further improvement, including the more detailed calculation of risk coefficients related to tree species, forest site type, location of forest districts within country regions, and also consequences of previous wind damage occurrences. For the mountainous areas, it would be important to develop risk models, which take into account land relief.