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Abstract: Understanding competition between trees is essential for sustainable forest management as interactions between trees in uneven-aged mixed forests play a key role in growth dynamics. This study investigated nine competition indices (CIs) for their suitability to model the effects of neighboring trees on silver fir (Abies alba) growth in Dinaric silver fir-European beech (Fagus sylvatica) forests. Although numerous competition indices have been developed, there is still limited consensus on their applicability in different forest types, especially in mature, structurally complex forest stands. The indices were evaluated using the adjusted coefficient of determination in a linear model wherein the volume growth of the last five years for 60 dominant silver fir trees was modeled as a function of tree volume and competition index. The results demonstrated that distance-dependent indices (e.g., the Hegyi height-distance competition and Rouvinen-Kuuluvainen diameter-distance competition indices), which consider the distance to competitors and their size, perform better than distance-independent indices. Using the optimization procedure in calculating the competition indices, only neighboring trees at a distance of up to 26-fold the diameter at breast height (DBH) of the selected tree (optimal search radius) and with a DBH of at least 20% of that of the target tree (optimal DBH) were considered competitors. Therefore, competition significantly influences the growth of dominant silver firs even in older age classes. The model based solely on tree volume explained 32.5% of the variability in volume growth, while the model that accounted for competition explained 64%. Optimizing the optimal search radius had a greater impact on model performance than optimizing the DBH threshold. This emphasizes the importance of balancing stand density and competition in silvicultural practice.
Keywords: sustainable forest management, Dinaric silver fir-European beech forests, Competition indices, CIs, optimal search distance, optimal diameter at breast height, DBH
Published in DiRROS: 05.06.2025; Views: 551; Downloads: 318
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Abstract: The ectomycorrhizal symbionts of silver fir have rarely been analyzed and identified, so little is known about their diversity and distribution. The aim of this study was (1) to analyze the diversity of ectomycorrhizal fungal species in three geographically distinct forest stands of Abies alba and (2) to demonstrate the high temporal variability of the ectomycorrhizal community over two consecutive growing seasons using repeated monthly sampling. Root samples were taken every month during two growing seasons in three silver fir-dominated forest stands. The ectomycorrhizal root tips were first assigned to a morphotype based on morphological characteristics and then identified by sequencing the internal transcribed spacer region. Alpha and beta diversity differed significantly between all three study sites, with the most diverse and even ectomycorrhizal community described in plot Jelovški boršt. The diversity indices over the growing season were different at two of the three study sites, supporting the idea of a fluctuation of ectomycorrhizal taxa during the growing seasons of the two consecutive years. While significant temporal variability was only confirmed for certain ectomycorrhizal taxa, there were no significant changes in the ectomycorrhizal community in general. Thus, we confirmed the high spatial but low temporal variability of the ectomycorrhizal community associated with silver fir.
Keywords: ectomycorrhizal community, spatiotemporal variation, silver fir, fungal diversity, forest, root-associated fungi
Published in DiRROS: 31.01.2025; Views: 585; Downloads: 402
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Keywords: climate-growth limitation, VS model, Carpathians, climate change, silver fir, European beech
Published in DiRROS: 03.09.2024; Views: 982; Downloads: 598
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Abstract: Predicting global change mitigations based on environmental variables, like temperature and water availability, although yielding insightful hypothesis still lacks the integration of environmental responses. Physiological limits should be assessed to obtain a complete representation of a species’ fundamental niche. Detailed ecophysiological studies on the response of trees along the latitudinal gradient are rare. They could shed light on the behaviour under different light intensities and other studied traits. The forests of the Dinaric Mountains and the Carpathians represent the largest contiguous forest complexes in south-eastern Europe. In uneven-aged Carpathian (8 plots) and Dinaric Mountain (11 plots) forests, net assimilation (Amax) and maximum quantum yield (Φ) were measured for beech and fir in three predefined light intensity categories according to the indirect site factor (ISF%) obtained by the analysis of hemispherical photographs in managed and old growth forests, all located above 800 m a.s.l. The measurements were carried out under fixed environmental conditions in each light category per plot for three consecutive years. Data from the last 50-year average period from the CRU TS 4.01 dataset were used for the comparison between Amax, Φ, and climate. The highest Φ for beech were observed in the central part of the Dinaric Mountains and in the south westernmost and northwesternmost part of the Carpathians for both beech and fir, while they were highest for fir in the Dinaric Mountains in the northwesternmost part of the study area. The Φ-value of beech decreased in both complexes with increasing mean annual temperature and was highest in the open landscape. For fir in the Carpathians, Φ decreased with increasing mean annual temperature, while in the Dinaric Mountains it increased with higher temperature and showed a more scattered response compared to the Carpathians. Short-term ecophysiological responses of beech and fir were consistent to long-term radial growth observations observed on same locations. The results may provide a basis and an indication of the future response of two tree species in their biogeographical range to climate change in terms of competitiveness, existence and consequently forest management decisions.
Keywords: silver fir, beech, light response, Carpathian Mountains, Dinaric Mountains, temperature, precipitation
Published in DiRROS: 08.05.2024; Views: 1254; Downloads: 998
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Abstract: esearch Highlights: Data of advanced-age provenance tests were reanalyzed applying a new approach, to directly estimate the growth of populations at their original sites under individually generated future climates. The results revealed the high resilience potential of fir species. Background and Objectives: The growth and survival of silver fir under future climatic scenarios are insufficiently investigated at the xeric limits. The selective signature of past climate determining the current and projected growth was investigated to analyze the prospects of adaptive silviculture and assisted transfer of silver fir populations, and the introduction of non-autochthonous species. Materials and Methods: Hargreaves% climatic moisture deficit was selected to model height responses of adult populations. Climatic transfer distance was used to assess the relative drought stress of populations at the test site, relating these to the past conditions to which the populations had adapted. ClimateEU and ClimateWNA pathway RCP8.5 data served to determine individually past, current, and future moisture deficit conditions. Besides silver fir, other fir species from South Europe and the American Northwest were also tested. Results: Drought tolerance profiles explained the responses of transferred provenances and predicted their future performance and survival. Silver fir displayed significant within-species differentiation regarding drought stress response. Applying the assumed drought tolerance limit of 100 mm relative moisture deficit, most of the tested silver fir populations seem to survive their projected climate at their origin until the end of the century. Survival is likely also for transferred Balkan fir species and for grand fir populations, but not for the Mediterranean species. Conclusions: The projections are less dramatic than provided by usual inventory assessments, considering also the resilience of populations. The method fills the existing gap between experimentally determined adaptive response and the predictions needed for management decisions. It also underscores the unique potential of provenance tests.
Keywords: climate change, common garden, provenance test, silver fir, grand fir, Balkan firs, drought stress, resilience, climate transfer distance, adaptation
Published in DiRROS: 05.07.2021; Views: 1944; Downloads: 1321
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