The practice of salvage logging dead and damaged timber following large high severity disturbances has raised much controversy, partly because of the negative ecological effects that such practices have on forest ecosystems. Many of the studies on salvage logging effects, however, have been done on sites damaged by large, severe disturbances. Less is known about the ecological consequences of salvage logging following intermediate severity disturbances that cause partial canopy damage at smaller scales. We examined the response of the herbaceous layer and tree regeneration to salvaged and non-salvaged treatments following small-scale intermediate severity disturbances in eight mixed beech (Fagus sylvatica L.) dominated forest stands in Slovenia. The cover and diversity of herbaceous vegetation, as well as the density and diversity of tree regeneration were similar between treatments across the study sites.The only notable differences between the treatments were that salvaged sites had a larger proportion of shade intolerant tree species in the regeneration layer, while non-salvaged sites tended to have a more well developed regeneration layer in taller height classes. The results suggest that salvage logging following small-scale intermediate severity disturbances may not hinder forest recovery in mixed beech dominated forests.
Real-time synthesis of realistic tree models is a desirable functionality for computer games, simulators, and landscape design software. Self-organizing tree models that adapt to the environment are a welcome addition and central to various 3D design tools but present a challenging task for interactive use even on modern commodity hardware. The paper describes the implementation of a complete selforganizing tree synthesis method running on a contemporary graphics processing unit using OpenCL. We demonstrate that generation and display of tree-populated scenes with shadows at interactive rates can be achieved by utilizing the massively parallel GPU architecture to accelerate the computationally intensive steps of the method. A comparison with the performance of single-threaded and CPU-based OpenCL implementation of the same method is reported.
The research deals with the effects of forest tending on stand structure and composition on abandoned agricultural lands and possibilities of directing succession development of these stands. This attempt to evaluate the tending ran five vegetation seasons and was divided into three parts. In the first part we checked the initial condition and performed the tending. Setting the goals which are formed according to the development phase and consequent expediently performed silvicultural tending actions, on the abandoned agricultural lands in the thicket phase it is necessary to give priority primarily to the pioneer species due to their protective role, while in the pole stand phase the stress should be laid to the species, interesting from the silvicultural viewpoint, e.g. noble broadleaved trees, minority tree species and climax species. In the second (after three vegetation seasons) and third (after five vegetation seasons) part we again checked the condition and thereby the effects of tending. We applied statistical methods for studying the effects of tending. With the tending we stimulated shifting of the tree species, which are important stand builders in the preliminary phases of succession (above all sycamore maple), and increased diameter increment of the crop trees. Through timely tending actions it is possible to stimulate natural succession on the abandoned agricultural lands and direct it toward economically interesting and ecologically stable forest, whereby it is necessary to stress that low intensity actions are needed for a stable stand, otherwise stand stability is endangered. On the lands, where other roles are in the foreground, stand quality is of secondary importance. The costs of thicket tending on abandoned agricultural lands are lower than the costs of pole stand tending.
Quantitative descriptions of natural disturbance regimes are lacking for temperate forest regions in Europe, primarily because a long history of intensive land-use has been the overriding driver of forest structure and composition across the region. The following contribution is the first attempt to comprehensively describe the natural disturbance regime of the dominant forest communities in the Dinaric Mountain range, with an emphasis on the range of natural variability of regime components for the main disturbance agents. Compared to other forest regions in Europe, the mountain range has a history of less intensive forest exploitation and provides a suitable record of natural disturbance processes. Our synthesis is based on multiple types of evidence, including meteorological information, historical documentation, evidence from old-growth remnants, and salvage logging data from National forest inventories. Taken together, the results show that no single disturbance agent dominates the regime in the dominant forest types (i.e. beech and mixed beech-fir forests), and any given agent exhibits remarkable variation in terms of severity and spatial extent both within and among individual disturbance events. Thunderstorm winds cause the most severe damage (i.e. near stand replacement), but blowdown patches are typically limited to stand-scales (e.g. 10s of ha). Ice storms and heavy snow typically cause intermediate severity damage and affect much larger areas (e.g. 100s of km2). A notable exception was the 2014 ice storm, which was nearly an order of magnitude larger and more severe than any other event recorded in the synthesis. Severe and prolonged periods of drought have occurred several times over the past century, and along with secondary insect damage (e.g. bark beetles), have caused episodes of forest decline. Overall, our synthesis indicates that on top of the background of relatively continuous gap dynamics, stand-scale intermediate severity events are an important part of the regime; these events likely have rotation periods that are less than the lifespan of a tree cohort (e.g. several centuries) and create canopy openings large enough to alter successional trajectories.
We studied regeneration dynamics in forests disturbed by three different windthrow events in 2008 in Slovenia to assess the success of natural regeneration vs planting and subsequent silvicultural treatments. Fifty-three plots with planted saplings of Norway spruce and sycamore maple and 50 plots with dominant naturally regenerated saplings were selected in a randomly stratified manner. Sapling characteristics (height, height increment, root collar diameter, free-to-grow score, browsing and micro-site) were assessed in 2012 and 2014. Herbs and seedling establishment were studied in two subplots within each plot. Average seedling density was 13,074 and 14,674 ha%1 four and six years after the windthrows, respectively. Seedlings were irregularly distributed, which suggests micro-site differences in regeneration dynamics. The results indicated lower seedling success on sites that were southerly exposed, farther from the forest edge and seed trees, on undisturbed micro-sites and at higher altitudes. On such sites planting was justified. While seedling density indicated a positive relation to herb coverage, sapling survival was negatively associated with it as well as with browsing. Initial sapling height was the strongest predictor of survival. Spruce saplings had the lowest mortality, while shade-tolerant silver fir and beech experienced high mortality. The study indicated a high density and species diversity of naturally regenerated seedlings within windthrow areas, which was reduced by planting, mowing of competing vegetation and protection measures favouring planted saplings. Recommendations for the improvement of silvicultural operations for post windthrow restoration are given.