Issues

Abstract

Surface and canopy fuel characteristics that influence the initiation and spread of wildland fires were measured in representative Black pine (Pinus nigra) plantations in Southern Bulgaria. Potential fire behavior (type of fire, probability of crown fire initiation, crown fire type, rate of spread, fire line intensity and flame length) in Black pine plantations was simulated with the most updated fire behavior models. The probability of crown fire initiation was high even under moderate burning conditions, mainly due to the low canopy base height and the heavy surface fuel load. Assessment of surface and canopy fuel characteristics and potential fire behavior can be useful in fuel management and fire suppression planning.
 

Abstract

Vertical gardens are a special type of interior phytodesign, getting more and more popular in the world landscape practice. They are specific arrangements of ornamental plants created in the exterior as well as in the in-door spaces, forming a self-maintaining system. In the interior the most appropriate and commonly used are the epiphytes. Principles of nutrition and their requirements to the environmental conditions are prerequisites for a successful use in the vertical gardens. In specialized collections and sales network in our country, that offer a variety of ornamental epifitytes, the plants are used and often treated as terrestrial plants. This article presents an analysis of the species composition of epiphytes in real world models of vertical gardens and the assortment of such species kept in collections or commercially available in our country. A survey on the diversity of imported and grown epiphytes carried out in June-September 2009 is presented. Totally 10 sites are audited (9 commercial garden centres and also the greenhouses of the Institute of Ornamental plants - Negovan).
 

Abstract

The aim of the present study was to study success and development of coniferous trees for the needs of intensive plantations for biomass production, used in the recultivation process of mine-spoilt banks of opencast mines in the Kolubara basin. For this purpose, an experiment with European larch seedlings, aged 2+0, which lasted for four years in plots with seven repetitions was set. The distance between the rows with the seedlings was 1 m, and 2.5 m between the plants in a row. Out of the initial 1,000 seedlings 90.5% and 77.4 % survived in the first and second year after planting, respectively. At the later stages, the decay of the plants almost stagnated (up to 74.8%). From autmn 2007 to spring 2010 total height increment of seedlings was 1.17 m. Total root collar diameter increment was nearly1.9 cm. The highest increment was reported during the last vegetation of seedlings (in spring 2010): diameter increment was about 1.2 cm and height increment was about 0.9 m. Differences between seedlings from sludge treated and untreated, control deposols (measured in spring 2010), were significant. Treated seedlings showed better results in mean root collar diameter as well as in mean height of seedlings (2.5 cm and 1.7 m, respectively) in comparing with untreated (control) ones (1.9 cm and 1.0 m, respectively). The results obtained justify the future more intensive establishment of plantations of this fast-growing conifer species. European larch also appears to be suitable for growing on mechanically damaged substratum.
 

Abstract

The importance of the soil organic matter pool on the terrestrial carbon (C) cycle is clearly reflected by the fact that every year around 10% of the atmospheric C circulates throughout the biomass and the soil. Not only the size of this pool but also the composition and lability of the organic compartments have a notable influence on the soil CO2 emissions, since its nature determines the resident times and persistence of the different C compounds into the soil. Therefore, two different types of deciduous forests of the temperate-humid zone (Quercus robur L. or Betula alba L.) were studied in order to evaluate the biodegradative processes of their soil organic matter. In Galicia (Northwestern Spain), 24 permanent forest plots were established to determine their potential C mineralization activity using long term incubation experiments that were carried out under laboratory controlled conditions. The cumulative data of the potential soil CO2 effluxes were fit to a double exponential kinetic model that considers two C pools of different lability and different instantaneous mineralization rates in order to estimate the labile and recalcitrant C pools in these soils. Differences on the total soil C content as well as on the soil organic matter mineralization kinetics between both forest types were found and the implications of the results obtained in the global warming mitigation strategies are discussed. The results obtained are useful not only to evaluate the quantity of CO2 released to the atmosphere from these Atlantic forests but also to contribute to a better prediction of the C balance in a global warming scenario.
 

Abstract

It is widely accepted that increasing concentrations of "greenhouse gases" will raise the temperatures of the Earth's atmosphere and oceans. By acting as C sinks, forest ecosystems can store significant amounts of CO2. There is, therefore, a growing need to evaluate the C cycle in forest ecosystems. Quatification of the C stored in forests, both in plants and soils (global balance between CO2 fixation and CO2 emission), and the knowledge of the main factors affecting net C fluxes in these ecosystems are basic and essential tools to control this environmental problem. This research work encompasses the study of the seasonal variations of the CO2 emissions from soils of two different types of deciduous forests of the temperate-humid zone (Quercus robur L. or Betula alba L.) located in Galicia (Northwestern Spain). With this objective, permanent forest plots were established and in situ determinations of soil CO2 effluxes were assessed using a portable infrared gas analyser. The determinations of the exchanges of this gas through the soil-atmosphere interphase were periodically carried out during a whole year (winter, spring, summer and autumn) in order to quantify the seasonal variations of these soil emissions. The significance of the seasonal variations observed for both types of forests and the implications of the results obtained in the global warming mitigation strategies, as well as the relation of these CO2 effluxes with soil temperature, are discussed.
 

Abstract

Microsphaera alphitoides Griff. et Maubl. is the most widespread and frequent disease in oak forests.The fungus is primary pathogene attacking plants in all developmental stages. Since it causes the greatest harms on young stands of pedunculate oak, when attacks are strong, chemical protection (treatment by fungicides) is applied. In Serbia fungicides for control of pathogenes in forest ecosystems are not registered. Therefore, it is necessary to select ecotoxicologically favourable fungicides registered in this region and obey FSC policy in application of pesticides. Bionfungicides are used for biological control of fungi causing plant diseases. This paper studies the independent influence of biofungicide AQ10 in concentrations 0.03 g, 0.05 g, and 0.07 g on agent of oak mildew. Preliminary studies of effect of biofungicide AQ10 are conducted by standard OEPP method PP1/69(2) (OEPP/EPPO, 1997) in pedunculate oak nurseries subject to infection potential of parasitic fungus M. alphitoides. Leaf infection was estimated by EPPO method (Guideline for efficacy evaluation of fungicides Podosphaera leucotricha) PP1/69(2); infection intensity was determined by Towsend-Heuberger's method, and efficiency by Abbott's.
 

Abstract

The aim of this study was to analyze height structure of pure Juniperus excelsa stands in Prespa National Park in Greece. Since many trees in these stands are multi-stemmed, the height structure based on the tallest stem in each tree was chosen as a representative measure of stand structure. During the summer of 2009, a plot of 100 m x 100 m, which was divided in four subplots of 50 m x 50 m, was established in a medium site quality stand, while a plot of 50 m x 50 m was established in a good site quality stand. Moreover, 90 plots of 25 m x 20 m were established in juniper stands and groups having different canopy cover percentage and forms of J. excelsa trees in good and medium site quality areas. In all plots the height of the tallest stem of each tree was measured. In most stands, in both sites, the height class of 5 m dominates in height structure. However, in some cases the class of 3 m dominates in medium site qualities and the class of 7 m in good site qualities. The highest trees found in medium and good site qualities were 12 m and 14 m respectively. The density of J. excelsa groups and stands ranged from 80 to 580 J. excelsa trees per ha. The rather low tree-height of Juniper trees in Prespa National Park as well as the height structure and density of J. excelsa stands are the result of anthropogenic disturbances. The results of this study will contribute to the knowledge and protection of this rare ecosystem in Greece.
 

Abstract

There are numerous design techniques that can be used to reduce the reduce impacts from surface-disturbing projects. The techniques described should be used in conjunction with visual resource contrast rating process wherein both the existing landscape and the proposed development or activity are analyzed for their basic elements of form, line, color, and texture. This discussion of design techniques is broken down into two categories: design fundamentals and design strategies. Design fundamentals are general design principles that can be used for all forms of activity or development, regardless of the resource value being addressed. Applying these three fundamentals will help solve most visual design problems: proper siting or location, reducing unnecessary disturbance, repeating the elements of form, line, color, and texture. Design strategies are more specific activities that can be applied to address visual design problems. Not all of these strategies will be applicable to every proposed project or activity: color selection, earthwork, vegetative manipulation, reclamation/restoration, linear alignment design considerations. The fundamentals and strategies are all interrelated, and when used together, can help resolve visual impacts from proposed activities or developments. The techniques presented are only a portion of the many design techniques available to help reduce the visual impacts resulting from surface-disturbing activities or projects. Further research into planning and design references and/or consultation with professional designers and engineers will help to further reduce the visual impacts of any development.
 

Abstract

The wild trout biomass density in four tributary streams of the Maritza river (Topolnitsa, Stryama, Yadenitsa and Chepinska) was investigated by electrofishing. The study was carried out in 100 m long closed test areas, from mid summer to autumn 2008. The theoretical density for two consecutive catches was calculated. It was found that the areas of populations of wild trout in the Topolnitsa and Stryama creeks are fragmented and with a very low-rate density. The theoretical density of wild trout estimated is as follows: for the Chepinska stream - 446 ha-1 and for the Yadenitsa stream - 608 ha-1. The theoretical number of wild trout with a length of 23 cm and more was calculated for the Stryama stream - 15 ha-1, for the Yadenitsa stream - 12 ha-1, and for the Chepinska stream - 4 ha-1 respectively. Within the four studied creeks the highest rate of wild trout theoretical biomass was found to be that of the Yadenitsa stream - 26.27 kg.ha-1, followed by stream Chepinska with 20.43 kg.ha-1. The quantity of fish allowed for fishing, with a length of 23 cm and more, according to the Law (Anonymous 2006), was very low in all the four creeks that were studied.
 

Abstract

A dynamic whole-stand growth model for birch (Betula pubescens Ehrh.) stands in Northwestern Spain is presented. In this model, the initial stand conditions at any point in time are defined by three state variables (number of trees per hectare, stand basal area and dominant height), and are used to estimate total or merchantable stand volume for a given projection age. The model uses three transition functions expressed as algebraic difference equations to project the corresponding stand state variables at any particular time. In addition, the model incorporates a function for predicting initial stand basal area, which can be used to establish the starting point for the simulation. Once the state variables are known for a specific moment, a distribution function is used to estimate the number of trees in each diameter class by recovering the parameters of the Weibull function, using the moments of first and second order of the distribution. By using a generalized height diameter function to estimate the height of the average tree in each diameter class, combined with a taper function that uses the above predicted diameter and height, it is then possible to estimate total or merchantable stand volume.
 

Abstract

Rapid growth is one of the most valuable characteristics of Douglas fir. In order to make the best use of this feature of its, it is necessary to investigate the growth characteristics of this tree species at level population. The objective of this research is to contribute in identifying promising provenances of Douglas fir in the experimental plantation in Konyavska Mountain. In order to attain the above objective methodologies for establishment and assessment of provenance experiments, early tests and statistics were applied. The average values for height of the trees for a period of five consecutive years: 5, 6, 7, 8 and nine as well as the current height increment for four years for each provenance in the trial plantation established with provenances from the states of Oregon, Washington, Arizona and New Mexico in State Forest Service Kyustendil were estimated. Based on data about the sums of precipitation and air temperature, drought and semi-drought periods were determined for corresponding years. The provenances are determined as promising if they meet the following two conditions: to be at the top of classification according to reached height and current increment in height, and to be of current increment in height influenced by the duration of dry and semi-dry periods to the least extent.
 

Abstract

In this paper an experimental study is exposed which has been conducted for determining the angles and the friction coefficients of seeds of some coniferous tree species. These parameters are used in the design and construction stages of forest planters and seeding machinery. These parameters can also be applied in the technological research of many forestry processes such as: dewinging, cleaning, sorting, seeds sowing etc. The object of research are seeds of some of the main coniferous tree species which are a subject of economic activity in our country - Scots pine (Pinus sylvestris L.), Black pine (Pinus nigra Arn.), Norway spruce (Picea abies Karst.) and Macedonian pine (Pinus peuce Griseb.). As a result of this study, the angle parameters and the friction coefficients of the studied seeds have been established. Results can be used in the design of forestry machinery and in the research of technological processes connected to the movement and processing of seeds.
 

Abstract

An environmental estimation is made of regenerative cuts in mountain beech (Fagus sylvatica L.) stands, based on a motormanual prime processing and transportation by wheel cable skidders. After the mechanized regenerative cuts, about one-third of the residual trees are damaged, fortunately most of them superficially. Predominantly the tree roots and stems are damaged. Inside the stands, the number of damaged trees is smaller, whereas around the skid roads almost half of the trees are damaged. In the first case, the residual trees are damaged by the felled trees (mainly higher than the first 1 m of the stem). In the second case the damages are caused by the skidded stems. The results show that the percentage of damaged understorey is about 16.89%, including 80% of it recoverable. To reduce tree damages along the skid roads and especially those along the curves, it is advisable to use some protective devices for prevention. To minimize the damages on the understorey it is necessary to use protective X-devices, diverting rollers and cones on the front of the logs. It is advisable to improve the professional skills of the loggers and to introduce effective stimulations for environmentally-sound logging operations.
 

Abstract

The aim of this study is to evaluate the wood chips production as fuel for energy sector in the State Forests Enterprise of Slovak Republic logging conditions. Working operations of primary transport are analyzed – ground-based skidding systems that drag or carry logs from stump to landing, transportation of energy wood chips in containers. The main result of the research is the possibility to optimize the energy wood chips transportation methods from environmental and economical point of view. The paper deals with the knowledge and experience of increasing the value of less valuable wood from thinnings.

Abstract

Forest policy and forest carbon accounting systems must be underpinned by appropriately accurate information, yet such information is often difficult and expensive to collect. This has led to the promotion of more cost-efficient forest sampling methodologies, and to the rise of modeling as a means to predict or interpolate changes to forest conditions in response to various stimuli. The accuracy of such modeling is usually determined through comparison with field data, often collected at a relatively limited number of sites.
Large bodies of relevant forest data are collected in National Forest Inventories, but there are inherent methodological problems in using this NFI data for model validation, particularly if such data is collected using angle-count sampling. Angle-count sampling has the advantage of being a relatively fast and cheap method of collecting forest data, but it is generally considered that at least four samples should be taken at a site for the results to be usefully precise. Some NFIs however take only a single angle-count sample at each fixed sampling point. Although at a broad scale these results may give useful figures, their usefulness at the plot scale is severely limited, especially if the intent is to judge plot timber volume increments or prepare forest carbon budgets. The availability of a time series does however allow for some statistical correction to single angle-count estimations. This study demonstrates the statistical uncertainties in using angle-count time series, and develops a method of reducing such 0 to a level that angle-count NFI data may be usefully used for comparisons with forest models.
 

Abstract

Beech forests in the Western part of Bulgaria have been monitored in order to assess the risk of harmful effects of lead (Pb) and cadmium (Cd) pollution by means of Critical Loads calculations and their exceedances by real deposition. Critical loads of Pb and Cd for two sites (Vitinya and Petrohan) have been determined using the 'Steady State Mass Balance' method based on the heavy metal uptake by the biomass and the leaching of the metals in the root zone. Real deposition of Pb and Cd was measured every two weeks during a one-year period by collecting the throughfall in plastic collectors (6 for each site). All samples have been analysed for their Pb and Cd content using atomic emission spectroscopy. The same method has been applied for measuring the content of Pb and Cd in the wood of beech trees. Fluxes of leaching water were measured in grid cells of 10 x 10 km for the entire country. The results obtained show that the critical loads of both Pb and Cd are lower for the Vitinya site demonstrating the higher sensitivity of beech to the pollution of heavy metals in comparison with the Petrohan site. In addition the real deposition of Pb and Cd has been higher at the Vitinya site. Although there were no exceedances of critical loads of Pb for both sites, additional deposition in the future will lead to a sooner exceedance of the critical load at the Vitinya site as compared to the Petrohan site. We conclude that the beech forest at the Vitinya site is at risk of damages by Cd pollution whereas the beech forest at the Petrohan site is more tolerant to heavy metal pollution due to its higher critical loads.

Abstract

The main objective of this study is to derive a diameter distribution model for Scots pine (Pinus sylvestris L.) plantations in Bulgaria, which predicts with high confidence the allocation pattern of the tree diameters from stand level variables. As the investigated stands showed predominantly unimodal distribution pattern, their diameter distributions were characterized by 2-parameter Weibull function. Six methods for its parameter estimation were examined: two methods for parameter recovery through moments (PRM_L and PRM_S), a method for parameter recovery through the stand basal area (PRM_B), two parameter prediction methods (PPM_NLS and PPM_MLE), and a modified parameter prediction method based on a mixed-effect model (PPM_Mixed). An empirical percentile model, not connected to a predefined functional form of the distribution, was fitted for comparison. The choice of the best performing model involved estimation of ranks based on Kolmogorov-Smirnov test and Error Index values for goodness of fit evaluation, against a fit and a validation data sets. Two of the parameter recovery methods (PRM_L and PRM_S) and one of the parameter prediction methods (PPM_NLS) performed best, PRM_S being the overall outperformer and PRM_L being the simplest for application. The empirical percentile model ranked fourth and was not advantageous for representing diameter distributions of Scots pine plantations. The two best models derived (PRM_L and PRM_S) describe well the diameter allocation pattern of the Scots pine plantations in Bulgaria and can be applied to estimate the diameter distributions from stand level variables in a simple and reliable way.
 

Abstract

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