M. Zasada

Comparison of selected statistical distributions for modelling the diameter distributions in near-natural Abies–Fagus forests in the Świętokrzyski National Park (Poland)

The aim of the study is to compare selected theoretical distributions (normal, lognormal, Weibull, gamma, logistic, and exponential) in describing the tree diameter (DBH) distributions of mixed near-natural forests consisting of fir Abies alba Mill. and beech Fagus sylvatica L. growing in various vertical structures. Tree DBH data were collected between 1997 and 2008 from 51 sample plots established in the Świętokrzyski National Park in Poland. The empirical data represent differentiated DBH distributions, ranging from almost symmetric to extremely asymmetric ones. The chi-square test and the modified Kolmogorov–Smirnov test were chosen for the goodness-of-fit testing. In addition to the test statistics, the bias (B), the root mean square error (RMSE) and the graphical method (quantile–quantile plots) were used. In one-storied stands, the most suitable distributions were the normal and logistic distributions; in two-storied and multilayered stands, the Weibull and gamma distribution were the most suitable; and in selection stands, the exponential distribution was the most appropriate to describe the DBH distribution. The order of precision of the tested distributions (from the highest to the lowest) was Weibull, gamma, logistic, normal, exponential, and lognormal. The normal and exponential distribution should be applied only to one-storied and selection forests, respectively. The least suitable distribution for DBH distribution modelling was the lognormal one.

Climate influence on radial increment of oak (Quercus SP.) in central Poland

The study investigates the influence of climate conditions on radial increment of oak, with special concern to the situations when analysed trees formed conspicuously wider or narrower tree-rings. The research material was collected in four locations in central Poland within natural range of pedunculate and sessile oaks. The elaborated residual chronologies were correlated with CRUTS 2.1 climate data. The analyses included thermal and pluvial conditions spanning from April of the year prior to ring formation to September of the current growth year. Special interest was paid to simple water ability index that combined both temperature and precipitation during the vegetation season. Additionally, pointer year analysis was carried out to determine situations when conspicuously smaller or larger increment was formed.Investigated chronologies cover the period of 1927–1992 (Łochów), 1845–1992 (Płońsk), 1868–1992 (Pułtusk), and 1796–1992 (Sokołów). The analysed oaks from sites in central Poland exhibit growth patterns comparable with those known form previous studies concerning that species, where influence of precipitation (higher and positive) and temperature (negative) have been observed. Extreme growth reactions expressed by negative and positive pointer years turned to present high dependence of analysed oak’ growth on water availability during vegetation season.

Fuzzy Hough transform-based methods for extraction and measurements of single trees in large-volume 3D terrestrial LIDAR data

This startup study suggests that more accurate and quicker methods of forestry terrestrial LIDAR data analysis can be developed, but new benchmark data sets with the ground truth data known are necessary for these methods to be validated. It follows from the literature review that the improvement in the methods can be attained by the use of newer Hough transform-based (HT) and other robust fuzzy methods for data segmentation and tree measurements. Segmentation of trees can be done by the limit fuzzification of the data around the breast height. Several HT variants having different properties can be applied to measure the diameter at breast height and the accuracies better than those offered by the commercial software seem to be attainable.

Spatially explicit biomass supply sustainability analysis for bioenergy mill siting in Georgia, USA.

Forest production sustainability is a broad and controversial subject that is frequently argued but rarely computed. Especially in the context of private forest ownership the results of erroneous assessment of forest production sustainability, such as in the case of woody biomass production for local mill operations, may result in economical losses, in lower regional employment rates, and decreased prosperity and competitiveness. We describe in this article a simulation-based quantitative approach to sustainability analysis of forest biomass production and utilization in the context of new bioenergy mill siting. The analysis is based on the best available forest inventory data and on the most up- to-date knowledge of natural resource growth and yield dynamics as modelled by various studies available in the literature. The data used includes the USDA Forest Service FIA forest survey data as well as an enhanced analysis of data indicating locations of Intensive Management Plantations (IMP) at a county level, since such information, while not publicly available, has a significant impact on biomass production expectations. Using these data, simulated according to the state-of-the-art knowledge of regional growth and yield characteristics, we determine sustainable harvest levels (SHLs) for the purpose of siting bioenergy mills for 10- to 20-year production cycles. The simulations are conducted for each individual county of Georgia for four radii of procurement areas. The derived county level information on sustainable levels of biomass production, which vary for different units of analysis, can be used as a reference for effective forest utilization planning and for mill siting.