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  • Author: Róbert Marušák x
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Abstract

There has been an increasing demand for environmental considerations (e.g. unharvested patches) in forest harvest scheduling in the last decades. In Slovakia and the Czech Republic, allowable cut indicators are not based on the spatial structure; thus, they are unable to incorporate these additional conditions. Many harvest scheduling models based on integer and mixed integer programming have been developed throughout the world, but their use in forest management in Slovakia and the Czech Republic is rare. These approaches have mostly been developed for clear-cut management systems and do not exist for shelterwood systems. Harvest scheduling approaches for a two-phase, small-scale shelterwood system and a clear-cut system are presented. The models also include environmental requirements that restrict area of forest stands that are not to be harvested over the planning horizon. A mathematical formulation of that requirement was integrated into the forestry decision support system Optimal to solve all analysed harvest scheduling alternatives for small-scale shelterwood and clear-cut systems. Our results indicated that the total harvest volume amounts could be higher when a two-phase, small- -scale shelterwood system is applied. While there are legal adjacency constraints regulating clear-cut harvests, the influence of additional environmental requirements on the total harvested amount is more restrictive for the shelterwood system because of greater area available for harvest. Both scenarios of maximization of harvested volume and net present value provided comparable results.

Abstract

Peatland Norway spruce (Picea abies L. Karst.) forests represent very valuable ecosystems with considerable importance for nature conservation. However, a lot of peatland forests have been drained or used for opencast mining of peat. Since dendrochronological and dendroecological studies on trees growing on peatlands in Europe are not many, this study aimed to reconstruct the impact of drainage to the growth of trees in forest stands older than 100 years in the moment of drainage. Dendrochronological analysis was performed on two 0.25-ha square sampling plots (50*50 m) in two pre-selected stands (control site vs. drained site) with similar natural conditions and age. The mean-value functions of the ring indices, comparing the drained site with the control site, in the period after 1940 revealed very similar radial-growth trends. After the year 1992, when one site was substantially drained, the radial-growth trends not showed any significant change. Likewise, the result of the independent two sample t-test for the period after 1992 has not revealed any substantial statistically important difference in the mean index between the control site and the drained site

Abstract

This paper presents two alternative approaches of final cut scheduling for a fifty year strategic planning horizon. One approach is represented by cutting percentage, which is a classical timber indicator commonly used in the Czech and Slovak Republics. The second approach is represented by two optimisation models of integer programming; the first model without spatial aspect and the second model including adjacency constraints. Both optimisation models are derived for the clear cut management system with the scheduling approaches applied on an example of a forest management area with over-mature stands.

The main aim of the paper is to compare two suggested optimisation models with the classical scheduling approach and to demonstrate their positive effect on the age class distribution of forests. The further aim is to include green-up constraints in the scheduling, which respect legislative conditions. The results show that even in the case of a single management system, without considering different ecosystem services, the optimisation model that does not consider the spatial aspect gives comparable results to the approach that r includes the adjacency constraints. The primary hypothesis, that the regular age-class distribution and flow harvesting cannot be achieved when considering green-up constraints, was rejected

Abstract

One of the expected consequences of climate change and its inherent phenomena to forest ecosystems is the gradual modification of their tree species composition (i.e. expansion of resistant species instead of less resistant ones). Climate change accompanied with increasing temperatures and a lack of precipitations may present a threat especially to spruce stands in the European part of the temperate zone. European beech is one of the possible forest tree species which might replace the potentially endangered spruce. In this paper, we observed, by using a combination of continual measurements and destructive whole-tree sampling, standing stocks of above-ground biomass (i.e. stem, branches, and foliage) and its annual net primary productivity (NPP) in naturally regenerated young stands of beech and spruce. We intentionally selected a site where the changing climate conditions are better suited to the ecological demands of beech rather than spruce (the species is dominant in the observed area). We recorded only small differences in the standing stock of stems of the beech, if based on tons per ha. However, this is in favor of spruce if based on cubic meters per ha. The largest difference between the species was found for the standing stock of foliage, spruce retained three times the biomass of beech. Also, beech allocated more carbohydrates to stem than spruce. On the other hand, we estimated nearly the same production of foliages and branches in both stands.

Abstract

Extracting cores from a tree using an increment borer has been standard practice in dendrochronological studies for a long time. Although empirical rules exist regarding how many samples to take and which methodology to apply, comparatively few studies provide quantification of the similarity of relative tree-ring-widths (TRW) around the stem circumference. The aim of this study was therefore to precisely measure the similarity of standardised TRWs around the stem circumference and to provide objective suggestions for optimal core sampling of Norway spruce (Picea abies Karst. [L.]) and European beech (Fagus sylvatica L.) growing in Central European temperate forests.

A large sample of cross-sectional discs was used from Norway spruce and European beech trees growing on various slopes, at different altitudes and biogeographic regions across the Czech Republic and Slovakia. The similarity of TRWs measured in different coring directions was analysed by testing the relativized TRW around the trunk (rTRW). Comparison of rTRWs revealed no significant differences between coring directions, indicating that the relative increment was the same around the radius. The results also showed the high similarity between the rTRWs to be independent of both slope inclination and altitude. Moreover, the reconstruction of proportional tree diameters and basal areas backward in time from one core sample and one measurement of tree diameter (basal area) at the time of sample extraction is possible with reasonable precision.

Abstract

The Small-leaved lime (Tilia cordata Mill.) is currently not commercially important species, therefore the knowledge of biomass partitioning in a tree is rather incomplete. Moreover, lime biomass is estimated mostly using biomass functions designated for other species, without the knowledge of limits of such a use. For these reasons, we developed functions for the estimation of lime biomass in the aboveground woody parts. The functions were parameterized using 81 tree samples collected in two plots in the Czech Republic. In addition, we compared the biomass estimates produced by our functions with estimates produced by a function for beech, which have been obviously used as a surrogate for missing lime models in the Czech Republic and Slovakia.

On average, 78% of lime aboveground biomass was found to account for tree stem, 20% for branches and 2% for stump. Average biomass density was 374 kg m−3 and no significant differences between tree compartments were found. Accuracy of all models in terms of the Root Mean Square Error (RMSE) significantly differed between tree diameter classes; in case of total aboveground biomass, the RMSE was ca. 20% of the average biomass weight in a given class up to a diameter of 45 cm, and then it rose sharply. The RMSE was higher in case of compartments with variable dimensions, such as branches and stump. RMSE was slightly higher in case of estimates produced using a beech-specific function than using that developed in the current study (average RMSE 27.95 and 29.42%, respectively); at the same time, beech-specific function overestimated lime stem biomass by ca 12%. The almost equal RMSE implies the usability of both parameterisations for lime biomass estimation, though the correction of the mentioned overestimation should be applied.

Abstract

The fine roots are considered the key organs for plant survival, growth and productivity. Measurement of fine roots variables is easily and conveniently achieved by means of digital image. The descriptive variables like root area, surface, total length and diameter distribution may be obtained from the image. Analysis of digital image consists from several steps, each of them represents potential source of the error. In this article we want to evaluate the automatic thresholding and its impact on principal variables obtainable from digital scans of the fine roots. We compare 16 different thresholding methods and compare them with the human processed binary images of roots of cork oak (Quercus suber L.). We found some of the thresholding methods perform significantly better than others in the estimation of total projected area however the length estimation error points out a little different order of accuracy

Abstract

In the past few decades, ecological and environmental issues have dominated the forest industry worldwide, but economic aspects have been much less studied in this dynamic period. However, a sustainable and efficient forest biomass supply is critical for socio-economic development in many regions, particularly in rural areas. Nature protection efforts have contributed to reduced harvesting quotas, which have resulted in an imbalance of the environmental functions of the forests and forest management, particularly wood supply.

Considering the size and distribution of forest production management units and the forest stands that compose those units, there is a clear need for improved decision-making tools that help forest managers in planning harvest sequences. The optimization of harvest scheduling should consider economic and spatial factors, which may reduce production costs by increasing the logistic efficiency. Moreover, incorporating maximum harvesting opening size constraints into planning can help preserve biodiversity.

This article presents a new spatial harvest scheduling model based on the integer programming method; it was developed using real data from a forest production unit located in the northern part of the southeast region of Brazil. The goal of the proposed scheduling approach is to maximize the net present value and concentrate the harvesting locations in each period. In spite of the fact that the object of the study is plantation forest under management different to common conditions in Europe or North America, the model is flexible and can be used in management of forest in Central Europe.