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Povzetek: Trees represent an important archive that can be used to reconstruct the spatial and temporal patterns of rockfall events. Rockfall impacts can be recorded in the form of anomalies in tree rings and impact scars on the tree stem. In this paper we demonstrate the use of an approach based on counting scars for reconstructing the frequency and spatial pattern of past rockfalls. The approach was applied by counting the visible scars on the stem surface of 52 European beech trees (Fagus sylvatica L.) in the area of the Trenta Valley, Slovenia. The average number of impacts per trees was 7, and the impacts were mostly classified as old, indicating reduced rockfall activity in recent years. The average recurrence interval was 31.8 years, which was reduced by 1.2 years by the application of the conditional impact probability. The spatial pattern of rockfall impacts shows that rockfall activity is higher in the middle part of the studied slope.
Ključne besede: rockfall, natural hazards, dendrogeomorphology, tree rings, stem scars, recurrence interval
Objavljeno v DiRROS: 01.04.2020; Ogledov: 3939; Prenosov: 2999
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Povzetek: An increased frequency of fire events on the Slovenian Karst is in line with future climate-change scenarios for drought-prone environments worldwide. It is therefore of the utmost importance to better understand tree-fire-climate interactions for predicting the impact of changing environment on tree functioning. To this purpose, we studied the post-fire effects on leaf development, leaf carbon isotope composition (%13C), radial growth patterns and the xylem and phloem anatomy in undamaged (H-trees) and fire-damaged trees (F-trees) of Q. pubescens with good re-sprouting ability in spring 2017, the growing season after a rangeland fire in August 2016. We found that the fully developed canopy of F-trees reached only half of the LAI values measured in H-trees. Throughout the season, F-trees were characterised by higher water potential and stomatal conductivity and achieved higher photosynthetic rates compared to unburnt H-trees. The foliage of F-trees had more negative %13C values than those of H-trees. This reflects that F-trees less frequently meet stomatal limitations due to reduced transpirational area and more favourable leaf-to-root ratio. In addition, the growth of leaves in F-trees relied more on the recent photosynthates than on reserves due to the fire disturbed starch accumulation in the previous season. Cambial production stopped 3 weeks later in F-trees, resulting in 60% and 22% wider xylem and phloem increments, respectively. A novel approach by including phloem anatomy in the analyses revealed that fire caused changes in conduit dimensions in the early phloem but not in the earlywood. However, premature formation of the tyloses in the earlywood vessels of the youngest two xylem increments in F-trees implies that xylem hydraulic integrity was also affected by heat. Analyses of secondary tissues showed that although xylem and phloem tissues are interlinked changes in their transport systems due to heat damage are not necessarily coordinated.
Ključne besede: pubescent oak, cambium, radial growth, xylem, phloem, anatomy, sub-Mediterranean
Objavljeno v DiRROS: 19.03.2020; Ogledov: 2420; Prenosov: 1290
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Povzetek: The conservation and sustainable use of forests and forest genetic resources (FGR) is a challenging task for scientists and foresters. Forest management practices can affect diversity on various levels: genetic, species, and ecosystem. Understanding past natural disturbance dynamics and their level of dependence on human disturbances and management practices is essential for the conservation and management of FGR, especially in the light of climate change. In this review, forest management practices and their impact on genetic composition are reviewed, synthesized, and interpreted in the light of existing national and international forest monitoring schemes and concepts from various European projects. There is a clear need and mandate for forest genetic monitoring (FGM), while the requirements thereof lack complementarity with existing forest monitoring. Due to certain obstacles (e.g., the lack of unified FGM implementation procedures across the countries, high implementation costs, large number of indicators and verifiers for FGM proposed in the past), merging FGM with existing forest monitoring is complicated. Nevertheless, FGM is of paramount importance for forestry and the natural environment in the future, regardless of the presence or existence of other monitoring systems, as it provides information no other monitoring system can yield. FGM can provide information related to adaptive and neutral genetic diversity changes over time, on a species and/or on a population basis and can serve as an early warning system for the detection of potentially harmful changes of forest adaptability. In addition, FGM offers knowledge on the adaptive potential of forests under the changing environment, which is important for the long-term conservation of FGR
Ključne besede: forest monitoring, forest genetic monitoring, forest genetic diversity, silviculture
Objavljeno v DiRROS: 20.02.2020; Ogledov: 2023; Prenosov: 1280
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Povzetek: Root-associated fungal communities are important components in ecosystem processes, impacting plant growth and vigor by influencing the quality, direction, and flow of nutrients and water between plants and fungi. Linkages of plant phenological characteristics with belowground root-associated fungal communities have rarely been investigated, and thus our aim was to search for an interplay between contrasting phenology of host ectomycorrhizal trees from the same location and root-associated fungal communities (ectomycorrhizal, endophytic, saprotrophic and pathogenic rootassociated fungi) in young and in adult silver fir trees. The study was performed in a managed silver fir forest site. Twenty-four soil samples collected under two phenologically contrasting silver fir groups were analyzed for differences in rootassociated fungal communities using Illumina sequencing of a total root-associated fungal community. Significant differences in beta diversity and in mean alpha diversity were confirmed for overall community of ectomycorrhizal root-associated fungi, whereas for ecologically different non-ectomycorrhizal root-associated fungal communities the differences were significant only for beta diversity and not for mean alpha diversity. At genus level root-associated fungal communities differed significantly between early and late flushing young and adult silver fir trees. We discuss the interactions through which the phenology of host plants either drives or is driven by the root-associated fungal communities in conditions of a sustainably co-naturally managed silver fir forest.
Ključne besede: host phenology, stand age, root-associated fungi, silver fir, fungal community
Objavljeno v DiRROS: 20.02.2020; Ogledov: 1972; Prenosov: 1390
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Povzetek: WorldClim version 1 is a high-resolution, global climate gridded dataset covering 1961-1990; a ˝normal˝ climate. It has been widely used for ecological studies thanks to its free availability and global coverage. This study aims to evaluate the quality of WorldClim data by quantifying any discrepancies by comparison with an independent dataset of measured temperature and precipitation records across Europe. BIO1 (mean annual temperature, MAT) and BIO12 (mean total annual precipitation, MAP) were used as proxies to evaluate the spatial accuracy of the WorldClim grids. While good representativeness was detected for MAT, the study demonstrated a bias with respect to MAP. The average difference between WorldClim predictions and climate observations was around +0.2 °C for MAT and -48.7 mm for MAP, with large variability. The regression analysis revealed a good correlation and adequate proportion of explained variance for MAT (adjusted R2 = 0.856) but results for MAP were poor, with just 64% of the variance explained (adjusted R2 = 0.642). Moreover no spatial structure was found across Europe, nor any statistical relationship with elevation, latitude, or longitude, the environmental predictors used to generate climate surfaces. A detectable spatial autocorrelation was only detectable for the two most thoroughly sampled countries (Germany and Sweden). Although further adjustments might be evaluated by means of geostatistical methods (i.e., kriging), the huge environmental variability of the European environment deeply stressed the WorldClim database. Overall, these results show the importance of an adequate spatial structure of meteorological stations as fundamental to improve the reliability of climate surfaces and derived products of the research (i.e., statistical models, future projections).
Ključne besede: spatial analysis, spatial interpolation, geostatistics, ecological mathematics
Objavljeno v DiRROS: 20.02.2020; Ogledov: 1736; Prenosov: 1047
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