Forest Research Institute Sofia

Sofia, Bulgaria

Forest Research Institute Sofia

Sofia, Bulgaria
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Zlatanov T.,Forest Research Institute Sofia | Velichkov I.,Forest Research Institute Sofia | Hinkov G.,Forest Research Institute Sofia | Georgieva M.,Forest Research Institute Sofia | And 4 more authors.
Sumarski List | Year: 2012

Richards, Lundqvist-Korf and Hossfeld growth functions were fitted to age-height data of European chestnut (Castanea sativa Mill.) dominant trees on the northern slopes of Belasitsa mountain, Southwest Bulgaria. The model prediction performance was evaluated using quantitative as well as qualitative examinations. Goodness of fit of each model was estimated by the coefficient of determination, F-test for significance of the regression and t-tests for significance of the coefficients of the model. Models were further compared by the evaluation of the standard error of the model and Akaike's Information Criteria. Site index curves were constructed following the "guide curve method" procedure. In accordance with the evaluation tests, the Richards function was chosen as most adequate to express the age-dominant height relationship. Accordingly, it was further employed as a guide function to derive site index curves for studied chestnut population. It was recommended that the growth model and the site index curves elaborated in the current study are used within the data range 10-110 years.

Zlatanov T.,Forest Research Institute Sofia | Velichkov I.,Forest Research Institute Sofia | Georgieva M.,Forest Research Institute Sofia | Hinkov G.,Forest Research Institute Sofia | And 3 more authors.
IForest | Year: 2015

Chestnut forests in the Belasitsa Mountain region of southwest Bulgaria were traditionally intensively managed as orchard-like stands for nut production. More recently, management intensity has been sharply reduced as a result of rural abandonment, which combined with the effects of chestnut blight has led to marked structural changes in these forests. The focus of this paper is on the seed-based regeneration potential and seedling survival of chestnut in mixed stands managed over the past 15 years. Results suggest that management of stands under a high-forest system is appropriate, and regeneration from seed has advantages over coppicing if competing species can be controlled. An investigation into “sanitation cutting” performed since the 1990s shows that this had not a successful response to blight infestations. © SISEF.

Eastaugh C.S.,University of Natural Resources and Life Sciences, Vienna | Eastaugh C.S.,Southern Cross University of Australia | Kangur A.,Estonian University of Life Sciences | Korjus H.,Estonian University of Life Sciences | And 6 more authors.
Baltic Forestry | Year: 2013

Forest Ecosystem models are diagnostic tools to assess and understand ecosystem processes. Conflicting interests such as simplicity, observability and biological realism must be addressed to ensure a well balanced modelling approach. Because field observations are usually only available for short time periods or for a limited number of locations, models are important to extrapolate in space and time. The key to a successful modelling approach relies on finding the appropriate scale but is often limited by the availability of input data. In the practice of forest modelling, it is often necessary to produce meaningful outputs on the basis of rather weak information. In this paper we discuss spatial and temporal scaling issues within empirical modelling. Following the case studies the paper demonstrates how models address cross-scaling problems as they are relevant for the required data as well as the decision making and implementation process of specific end user needs.

Zlatanov T.,Forest Research Institute Sofia | Schleppi P.,Swiss Federal Institute of forest | Velichkov I.,Forest Research Institute Sofia | Hinkov G.,Forest Research Institute Sofia | And 4 more authors.
Forest Ecology and Management | Year: 2013

Components of structural diversity of abandoned chestnut (Castanea sativa Mill.)-dominated and co-dominated forests along an altitudinal gradient in the Belasitsa mountain region of Southwest Bulgaria were evaluated, including: (i) tree species composition; (ii) differentiation in diameter, height and age; (iii) tree crown defoliation and light transmission; and (iv) regeneration composition and abundance. Competition between tree species and its influence on current stand structure were analysed. Lack of management had triggered rapid structural and successional development in formerly chestnut mono-dominated forests which have now been invaded by midseral and later seral vegetation dominated by European beech (Fagus sylvatica L.) and sessile oak (Quercus petraea Liebl.). Distribution of sample plots according to diameter differentiation for chestnut showed positive differentiation values (dominance of chestnut with respect to other species) in 43 of a total of 46 plots sampled. Structure is much more balanced in terms of height differentiation. In the absence of management, chestnut blight has been a major stress factor and is likely an important driver of chestnut decline. The proportion of chestnut trees infected by chestnut blight disease exceeded 80% in 28 plots. Nearly one third (31%) of all sampled trees were characterized by a degree of defoliation of more than 60%. Despite the low levels of light at the forest floor, the density of the regeneration stratum was relatively high (averaging 19,300ha-1). An important finding is the retained regeneration potential of chestnut (31% of all seedlings). Chestnut seedlings, however, appeared to be poorly adapted to shading and rapidly declined in density and growth while seedlings of most competitors survived longer and dominated the regeneration stratum. © 2012 Elsevier B.V.

Zlatanov T.,Forest Research Institute Sofia | Elkin C.,University of Northern British Columbia | Irauschek F.,University of Natural Resources and Life Sciences, Vienna | Lexer M.J.,University of Natural Resources and Life Sciences, Vienna
Regional Environmental Change | Year: 2015

The vulnerability of forest ecosystem services to climate change is expected to depend on landscape characteristic and management history, but may also be influenced by the proximity to the southern range limit of constituent tree species. In the Western Rhodopes in South Bulgaria, Norway spruce is an important commercial species, but is approaching its current southern limit. Using climate sensitive forest models, we projected the impact of climate change on timber production, carbon storage, biodiversity and soil retention in two representative landscapes in the Western Rhodopes; a lower elevation landscape (1000–1450 m a.s.l) dominated by mixed species forests, and a higher elevation landscape (1550–2100 m a.s.l.) currently dominated by spruce. In both landscapes climate change is projected to induce a shift in forest composition, with drought-sensitive species, such as Norway spruce, being replaced by more drought-tolerant species such as Scots pine and black pine at lower elevations. In the higher elevation landscape a reduction in spruce growth is projected, particularly under the more severe climate change scenarios. Under most climate scenarios a reduction in growing stock is projected to occur, but under some scenarios a moderate increase in higher elevation stands (>1500 m a.s.l.) is expected. Climate change is projected to negatively influence carbon storage potential across landscapes with the magnitude depending on the severity of the climate change scenario. The impact of climate change on forest diversity and habitat availability is projected to differ considerably between the two landscapes, with diversity and habitat quality generally increasing at higher elevations, and being reduced at lower elevations. Our results suggest that if currently management practices are maintained the sensitivity of forests and forest ecosystem services in the Western Rhodopes to climate change will differ between low and higher elevation sites and will depend strongly on current forest composition. © 2015 Springer-Verlag Berlin Heidelberg

Groen T.,University of Twente | Fanta H.,University of Twente | Hinkov G.,Forest Research Institute Sofia | Velichkov I.,Forest Research Institute Sofia | And 2 more authors.
GIScience and Remote Sensing | Year: 2012

Monitoring the response of tree lines to climatic change requires long time series. Therefore ground-based studies, initially designed for other purposes, are used, causing a bias in the sampling design. Using historical satellite data might overcome this bias. This study explores the usability of historical spy-satellite imagery from the United States Hexagon missions to detect changes in tree lines. We find that both vertical and horizontal errors are within acceptable boundaries (± 18.0 m in horizontal direction and 5.5 m in vertical direction) to detect change. This opens opportunities to explore tree line changes globally with a more robust sampling strategy.

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