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Warsaw, Poland

Forest management in the State Forests in the past two decades (1990-2009) focused solely on the aging of forest stands and augmentation of forest resources. This period saw an increase in the average age of forest stands from 54 to 61 years, the average standing volume from 186 to 245 m3/ha, and the share of harvested volume in annual increment volume from 50 to 58%. As a result, the share of stands older than 80 years increased from 21 to 28% while that of plantations and young stands decreased from 14.4 to 11%. This resulted in the deterioration of the health and sanitary condition of forests.

The studies initiated by Włoczewski in 1936 revealed changes in the species composition of forest stands in the Bialowieża National Park. This led to the question about what these changes would be in the future. The aim of our study was to predict changes in the volume of tree species in the so called Strict Reserve in the Białowieża National Park over the period of 40 years. A size-class growth model was developed for this purpose. The average merchantable timber volume for each of the eleven taxa was calculated for the successive 10-year intervals, and the increase in standing volume as well as the volume of tree loss (mortality) and ingrowth were calculated for these intervals. The empirical material was taken from the permanent and temporary sample plots. The permanent plots (160) were measured in 2000, 2002, 2004 and 2011. The empirical data were used to determine, separately for each species, the relationship between trees dbh and mortality (fig. 1), diameter growth (fig. 2) or the rate of saplings (height of 0.3-1.3 m) growth into the first dbh class (0.1-1.9 cm). The temporary sample plots (460) were measured in 1995 and 2005, and the data were used to validate the size-class growth model and predict timber volume in the period 1995-2005 (tab.). The results of the validation may indicate significant changes in standing volume for the majority of tree species in the period 2005-2045 (fig. 3). In 2045, hornbeam will dominate. The volume increment in the period 2005-2045 will remain at almost the same level, the volume of tree loss will decrease and the volume of ingrowth will slightly increase, beginning from 2015 (fig. 4). Only five taxa will have a significant share in the ingrowth throughout the period 2005-2045, of which approx. 85% will be hornbeam in the period 2035-2045 (fig. 5). The observed changes in the species composition of forest stands in the Bialowieza National Park may be the result of global, regional as well as local factors such as the pressure of herbivorous ungulates on young trees. Anticipating changes in the structure of forest stands may be useful in planning the protection of forest areas by reducing the impact of local factors on forest stands (regeneration) in an indirect way.

The adopted rotation age and prescribed cut are found not to be fully respected at any stage of regulation, planning and implementation of cutting plans. As a result, timber, the main crop in forestry, is not uniform in terms of rotation age and fails the adopted criteria of crop maturity. Protective forests are not subject to management unless cut determination derives from silvicultural needs, without specifying the criteria for these needs. The level of cuts subjectively determined by quality control inspectors is not respected in forest management practice and should be recommended for use in the forests administered by the State Forests.

Brach M.,Katedra Urzadzania Lasu | Bielak K.,Katedra Hodowli Lasu | Drozdowski S.,Katedra Hodowli Lasu
Sylwan | Year: 2013

Paper presents results of measurement accuracy evaluation of two laser rangefmders (TruPulse and ForestPro integrated with MapStar compass) mounted on monopod and tripod under the forest conditions. The precise data on spatial coordinates of 34 trees in the Rogów Arboretum and 8 points from the geodetic control network in the Głuchów Forest were used. The results show that the measurement sets equipped with ForestPro and MapStar were more accurate than TruPulse ones. However, no significant influence of applied stands on the measurement accuracy was observed.

Airborne laser scanning (ALS) technology allows collecting data describing top forest layer in a very accurate way. This provides a possibility to generate crown height models (CHM) with resolution in which single tree crowns can be detected. In presented study highly automatic algorithm for single tree detection is presented. FALCON II ALS acquired data in Forest Experimental Station in Rogów (central Poland). Data used for algorithm accuracy evaluation were acquired by measuring sample plots on VSD photogrammetric station. CHM with the resolution of 0.5 m has been used in the presented research. Algorithm, in automatic or semi-automatic way, defines single crowns. Each of the end segments was additionally processed for correctly defined size and area of the crown projection. Received accuracy of correctly detected trees was 69% for all samples (71% for pine stands and 61% mixed stands) in automatic method and 74% (78% and 65% respectively) in semi-automatic method.

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