•The structure of forest patches and their spatial distribution are benevolent.•Spatial distribution of urban forests in Ljubljana is still favourable.•The real fragmentation occurred during the ...construction of the highway beltline.•Connectivity changes and nature preservation can be presented by a spatial model.•Connectivity among forest cores is an important index of habitat conditions.
Urbanisation development influences surrounding landscape processes, which are reflected by landscape structural patterns. Forest areas are often regarded as a spatial reserve for present and future urbanisation needs, while at the same time they often represent the last remnant of natural environment. In the present research we analysed (1) the change in forest cover in the area of suburban forests of Ljubljana between 1975 and 2012, (2) the connectivity and conservation buffers as one of the foundations for the assessment of biodiversity functions. Between 1975 and 2012, all the forests with important cores were subject to clearings for settlement- and agricultural purposes, but clearing usually did not extend beyond forest edges. The real fragmentation occurred during the construction of the highway beltline.
In the area of Ljubljana, connectivity changes and connectivity loss in two different time periods are presented by a spatial model based on the Graph Theory which can also be used in spatial planning.
Due to the high percentage of forest cover and the favourable distribution of forest patches and cores around the city of Ljubljana, no connection is currently in danger; the weakest link is stretching from the centre of Ljubljana towards the southeast.
In the process of evaluating the biodiversity of urban forests, it will be necessary to add connectivity among forest cores as an important index while evaluating the favourable conditions of different habitat types.
Urban and peri-urban forests are strongly influenced by urbanisation and infrastructure-driven development. The main objective of the study is to evaluate and assess key factors characterising of ...urban and peri-urban forests in Slovenian regions with large differences in landscape fragmentation, from the Pannonian Plain to the Alps and the Mediterranean Sea. To assess landscape fragmentation and potential urban and peri-urban forests (UPFs), we used a spatial model of landscape structure and spatial characteristics of forests’ fragmentation and connectivity. The basis for estimating landscape structure and spatial characteristics of UPFs was tested for the 69 settlements with city status and for 150 smaller, rural settlements, which are the centres of individual municipalities. Of the 219 Slovenian settlements analysed, forest core areas within walking distance were estimated for 98% of the settlements. The proportion of the walking distance area with forest cover and 100 m or more from the forest edge is no more than one tenth of this area for 45% of Slovenian towns and for 42% of smaller settlements. By assessing the gradients of landscape ecological variables and accessibility of UPFs, it is possible to compare UPFs in different regions and take them into account when preparing guidelines for spatial planning based on landscape structure principles at the local level. Large differences in the landscape and UPF fragmentation within cities and settlements highlight the importance of spatial planning that adapts to the individuality of the landscape and each UPF.
Due to a long history of intensive forest exploitation, few European beech (Fagus sylvatica L.) old-growth forests have been preserved in Europe.
We studied two beech forest reserves in southern ...Slovenia. We examined the structural characteristics of the two forest reserves based on data from sample plots and complete inventory obtained from four previous forest management plans. To gain a better understanding of disturbance dynamics, we used aerial imagery to study the characteristics of canopy gaps over an 11-year period in the Kopa forest reserve and a 20-year period in the Gorjanci forest reserve.
The results suggest that these forests are structurally heterogeneous over small spatial scales. Gap size analysis showed that gaps smaller than 500 m(2) are the dominant driving force of stand development. The percentage of forest area in canopy gaps ranged from 3.2 to 4.5% in the Kopa forest reserve and from 9.1 to 10.6% in the Gorjanci forest reserve. These forests exhibit relatively high annual rates of coverage by newly established (0.15 and 0.25%) and closed (0.08 and 0.16%) canopy gaps. New gap formation is dependant on senescent trees located throughout the reserve.
We conclude that these stands are not even-sized, but rather unevenly structured. This is due to the fact that the disturbance regime is characterized by low intensity, small-scale disturbances.
The concepts of ecotopes and forest sites are used to describe the correlative complexes defined by landform, vegetation structure, forest stand characteristics and the relationship between soil and ...physiography. Physically heterogeneous landscapes such as karst, which is characterized by abundant sinkholes and outcrops, exhibit diverse microtopography. Understanding the variation in the growth of trees in a heterogeneous topography is important for sustainable forest management. An R script for detailed stem analysis was used to reconstruct the height growth histories of individual trees (steam analysis). The results of this study reveal that the topographic factors influencing the height growth of silver fir trees can be detected within forest stands. Using topography modelling, we classified silver fir trees into groups with significant differences in height growth. This study provides a sound basis for the comparison of forest site differences and may be useful in the calibration of models for various tree species.
Close-to-nature urban forests and remnants of natural vegetation represent an important opportunity for urban residents to experience daily perception of and access to the natural environment. ...Despite there being a high percentage of forest cover (59%) and a favorable structure of the prevailing forested landscapes in Slovenia, urban expansion and infrastructure-driven development has severely weakened the connectivity and conservation of urban and suburban forests. The majority of urban settlements lie within walking distance of the surrounding forests (<1 km). However, only close-to-nature forests with relatively low silvicultural inputs offer ecosystem services sufficient to fulfil the supply and demand of the expanding urban population. In order to estimate the conservation of forests in the open space of Slovenian settlements, we used a spatial model of landscape structure and forest connectivity. The model can be enhanced with patterns of corridors and stepping stones of natural vegetation in the landscape matrix to provide support in the decision-making process of landscape planning and the conservation of urban and suburban forests.
In the presented research, we studied the forest edge structure of urban and peri-urban forests on the outskirts of Ljubljana (Slovenia) consisting of a number of patches covering the collective ...surface of 1884 ha. They differ from each other according to the degree of fragmentation and by the share of the interior forest area. On the basis of LiDAR data, we conducted an analysis of the edges of the persistent forest patches and estimated them with regard to the land use they bordered on. The horizontal estimation of forest edges and the changes of forest edges, in the last decades, were estimated using digital orthophoto images of cyclic aerial surveys of Slovenia, from 1975 to 2018. The data, provided by LiDAR, were used to obtain an accurate estimate of forest edges and the metrics of their vertical canopy structure. On the basis of the canopy height model (CHM), we determined the height classes, the heights of the tallest trees, and indices of canopy height diversity (CHD) as variables subjected to a k-means cluster analysis. To determine the forest edge and trees stability, their heights and diameters at breast height (DBH) were measured and their canopy length and h/d (height/diameter) dimension ratios were estimated. In the study area of the Golovec forest patch, more than half of the forest edge segments (56%) border on residential buildings. After the construction of buildings, 54% of the newly formed forest edges developed a high and steep structure. Unfavorable h/d dimension ratio was estimated for 16% of trees, more among the coniferous than among the deciduous trees. Similar characteristics of newly formed forest edges bordering on built-up areas were determined in other sub-urban forest patches, despite the smaller share of such forest edges (19% and 10%, respectively). Tools and methods presented in the research enable the implementation of concrete silvicultural practices in a realistic time period and extend to ensure that adequate forestry measures are taken to minimize possible disturbances.
Stratification based on Slovenian forest typology has been proposed for sampling forest land-use/ land-cover data and changes over time. Using land-use map and forest typology map we evaluated ...geographic scales of variance for landscape-level indices and compared stratification by administrative units and regions. As forest prevails in 10 out of 12 statistical regions in terms of its surface area, these regions cannot be effective stratification tool for sampling and mapping land-use. Statistical regions accounted for 21 percent of the total variance of percent agriculture and 17 percent of total variance in amount of forest. Through the classification of quadratic 1 square kilometre tiles according to the typology of forest site types, somewhat greater proportion of total variance has been explained by stratification than on the spatial scale of statistical regions, although on the account of the high number of groups (29 strata). The great differences in fragmentation indices for these forest groups illustrate that the spatial scale for the formation of strata is smaller than the regional one.
Based on previous measurements from 1962 to 2017 on forest research plots located on former slash-and-burn farming areas in the cadastral municipality of Koprivna, the diameter and height increment ...as well as volume increments of the two main tree species - spruce and larch - were calculated. These set-aside natural research plots have a smaller mean basal area diameter, but the number of trees is higher than in comparable managed forests. Due to the high-density of tree stands over the past thirty years, radial increment of spruce and larch has declined. To determine the influence of environmental factors on radial growth of spruce and larch, a dendrochronological analysis was conducted. According to the dendrochronological analysis of radial increment of trees, the number of years with a negative response has been higher since 1984.
•Soil probing revealed high variability of soil development in the Dinaric Mountains.•Stem analysis of 65 dominant silver fir trees displayed differences in height growth.•Tree age and soil ...parameters were the key factors for height growth of trees.•Competition intensity and soil parameters were the key factors for radial growth.•The influence of competition on radial increment was the highest on leached soils.
Tree growth can be influenced by a wide variety of complex interacting factors. The contribution of soil to site productivity is confounded by the interactions between other site factors and silviculture. The contribution of soil properties to the growth of silver fir (Abies alba Mill.) was studied in the Dinaric Mountains, which are characterised by abundant sinkholes and limestone outcrops, resulting in diverse micro topography and different soil development at small spatial scales. Basal area increment and height growth data were estimated based on stem analysis of dominant silver fir trees (n=65) on a 50m×50m sampling grid, and competition intensity was determined. The soil development around each tree was defined using morphological properties of the genetic horizons based on soil probing (n=65×12). In the study area, the chemical and physical soil characteristics (based on 21 soil profiles) were favourable for plant growth. Soil parameters e.g. soil depth, thickness of genetic soil horizons, share of soil types around each tree and soil associations were the factors controlling tree growth. Tree age and competition intensity were also influential factors in the case of height and radial tree growth respectively. Positive effects on height and radial growth were confirmed also for available water capacity of soil and location of tree in slope position (in the sinkhole, out of the sinkhole). The decrease in specific basal area increment with increasing competition intensity was most evident for trees growing on leached soils. The coefficient of determination and the statistical significance of the relationship between height growth and soil association over the last 100years emphasised the cumulative effect of the soil condition on tree height growth.
On Pahernik's forest estate it is possible to monitor the effects and success of at least half a century of forest management with uneven-aged forests. Based on the data from the control sampling ...method and the laser scanning of Slovenia, we assessed the structural diversity of forest stands with indicators and indices of stand densities, species and structural diversity of the DBH classes, the stand height classes and their heights. We compared land use in cadastral municipalities where Pahernik property is located (Vuhred, Planina, Orlica and Hudi Kot) in 1825, with land use from 2017. In all of the analyzed cadastral municipalities, the forest area share in land cover grew in the period from the 19th to 21st century. Forest cover increased by 21 % between 1825 and 2014 on Pahernik property as a whole. Differences in stand densities and in stand diversity indices between the stands where forest was not present in the 19th century and the stands on persistently forested lands were not statistically significant. In the prevalent forest site type montane and altimontane Fagus sylvatica forests on silicate bedrock we estimated that growing stock was by 20 % higher than in comparable forests of this site type elsewhere in Slovenia. At higher growing stocks and high values of indices of DBH variability in forests at Pahernik's forest estate, the estimated stand densities SDI were not higher than in forests of comparable forest site types. We estimated differences in height and structure of stand canopy according to the gradients of height classes, which have an impact on forest management within the individual forest type.
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