Influence of herbivory pressure on the growth rate and needle morphology of Taxus baccata L. juveniles

Damage by herbivore grazing negatively influences the development of subsequent forest generations. Little is known about the long-term impacts of grazing and interactions between grazing and light conditions on sapling growth after the cessation of herbivory impact. In this study, Taxus baccata saplings were grown over a period of four years in artificial shading at 2, 8, 30 and 100% of full sunlight (described as initial light). These saplings were planted in fenced and unfenced plots in a mixed forest in Poland. After six years with no protection from grazing, deer pressure was eliminated by fencing. In this study, we analysed sapling growth and needle morphology five years after deer suppression. Overall, grazing had a negative significant impact on the growth rate and needle morphology of T. baccata saplings. Saplings damaged by herbivores had a height increment approximately one-third that of non-grazed saplings. The grazed yew saplings had a lower needle area and length and a higher specific leaf area (SLA) than non-grazed saplings. Initial and current light conditions did not influence tree growth rates and needle morphology. However, we found positive correlations between sapling height and both leaf area and leaf length and a negative correlation between sapling height and SLA. Browsed yews also had a greater tendency to form polycormic (multi-stemmed) individuals. Lower growth rates, smaller needles and polycormic stems indicate a strategy of “escaping” herbivory pressure even five years after elimination of deer pressure

Vital rates and their multidecadal trends in the fir-beech old-growth forest of Badínsky prales

The study aimed to quantify annual mortality and recruitment rates on permanent research plots in the Badínsky prales old-growth forest. The data measured in four stands originate from six censuses, which together cover a 48-year period. The mean annual mortality rate reached 4.2% (DBH > 2 cm) or 2.3% (DBH > 8 cm). The mortality peaked in the first part of the observation period, probably indicating an intermediate disturbance activity, and the subsequent declining trend led to minimum annual mortality during the last 20 years. We found substantially higher fir mortality in comparison with beech, primarily during the first decades of the measurement period. Among three size categories, the stems with DBH 2-8 cm showed the highest mortality rate. We detected the minimum fir recruitment rate throughout the observation period; on the other hand, the beech recruitment rate was relatively high responding to the open canopy. Standing and lying deadwood volumes indicated similar trends like mortality did, and high values of fir standing deadwood observed during the first decades can signify that a relatively high proportion of mortality was related to the fir decline caused by air pollution

Gap Structure and Regeneration in the Mixed Old-Growth Forests of National Nature Reserve Sitno, Slovakia

Forest management mimicking natural processes represents an approach to maintain mixed, uneven-aged stands at small spatial scales. The reliance on natural processes, especially on natural regeneration leads to the use of gap-based regeneration as a fundamental silvicultural technique. As a baseline for such management, we investigated mixed forest in unmanaged National Nature Reserve Sitno in the Western Carpathians, which harbours extraordinary diversity on a rather small scale. To quantify the impact of gaps on gap-filling processes and to assess the role they play in recently observed changes in tree species composition we established a large (2.5 ha) permanent research plot and surveyed the status of natural regeneration, forest structure, tree species composition, and disturbance regime. Our research highlights the long-term and contemporary difficulties in the establishment of Quercus petraea (Matt.) Liebl and Fagus sylvatica (L.). Based on the provided evidence, the native tree species diversity in one of the few preserved old-growth multi-species beech-oak forest remnants is not likely to persist, what could have many implications for future ecosystem functioning. Our results suggest that variation in gap size is an important factor contributing to composition of tree species composition of natural regeneration. The recent intermediate-scale disturbance pattern dominating the old-growth beech-oak forest is beneficial to canopy recruitment of species less shade-tolerant than Fagus sylvatica, as Acer pseudoplatanus (L.), Acer platanoides (L.), and Fraxinus excelsior (L.). We discuss possible factors behind observed shifts in tree species composition and limitations for application of gap dynamics to forest practice in managed beech-oak forest systems. Overall, results of this study may help to design silvicultural measures promoting mixed-species forests to deliver a range of desired ecosystem services

Deer game, a key factor affecting population of European yew in beech forests of the Veľká Fatra Mts, Slovakia

Browsing and bark peeling by ungulates is known to affect biodiversity and may constitute the main driving factor of single tree population dynamics. In Slovakia, European yew (Taxus baccata L.) is a threatened species protected by law and present in many protected areas. In the study, we emphasize that protecting land and individual plants may not be sufficient for maintaining of yew populations, unless controlling over damage by deer game is also undertaken. Our results show that in beech forests of the Veľká Fatra Mts, browsing and bark peeling constitute the main negative factor affecting yew seedling-sapling ingrowth transition, and the mortality and vitality loss of adult yew trees. We argue that ungulates may have a larger effect on biodiversity conservation than currently realized

Irregular Shelterwood Cuttings Promote Viability of European Yew Population Growing in a Managed Forest: A Case Study from the Starohorské Mountains, Slovakia

The increasing probability of Taxus baccata (L.) decline given climate change brings forth many uncertainties for conservation management decisions. In this article, the authors present the effects of applying regeneration cuttings since the year 2000 on the viability of the understory yew population. By collecting data from a stand located at the centre of the largest population of European yew in Slovakia, containing approximately 160,000 individuals, and analysing tree-ring records from 38 sampled trees, the improved performance of yews, including stem growth, seed production, and number of regenerated individuals, was revealed. Thinning the canopy by removing 15% of the growing stock volume per decade, combined with the subsequent irregular shelterwood cuttings, was assessed as a useful strategy. Moreover, lower radial growth of females compared to males, but simultaneously their similar response to climate, suggests a possible trade-off between reproduction and growth. Release cuttings of up to 30% of the standing volume in the vicinity of the female trees, executed in the rainy summers following warmer winters, and consistent elimination of deer browsing, can further enhance the positive effects of applied cuts on yew viability. Overall, the suggested active measures could be considered as an effective option to preserve the unique biodiversity of calcareous beech-dominated forests in Central Europe

Multi-decade tree mortality in temperate old-growth forests of Europe and North America

Aim: Old-growth, mesic temperate forests are often assumed to be structured by gap-phase processes, resulting in quasi-equilibrial long-term dynamics. This assumption influences management focused on simulation of natural disturbance dynamics and is embedded in most models of forest successional dynamics. We use multi-decade monitoring of permanent plots in old-growth forests to assess demographic assumptions directly with respect to tree mortality rates. Location: Sixteen sites in mesic, temperate old-growth forests in eastern North America and Europe with multi-decade monitoring. Time period: Variable across sites, spanning c. 20%78 years from 1936 to 2014. Major taxa studied: Tree species of late-successional, cool-temperate forests of Europe and eastern North America. Methods: We calculated and compared the annualized mortality rates (m), with confidence intervals, by species, size class and measurement interval, for tree species of sufficient abundance. Results: Retrospective analysis shows dynamic and diverse demographic properties across populations and sites. Stand-scale mortality rates of 0.7%2.5%/ year average higher than previous estimates for old-growth temperate forests. Variations among species, over time and among size classes, suggest that gap-phase models are inadequate to explain stand dynamics, implying instead that rare disturbance events of moderate severity have long-lasting effects in old-growth forests and that indirect anthropogenic influences affect old-growth, unlogged forests. Main conclusions: Multi-decade baseline data, essential for understanding community assembly and long-term dynamics in these %slow systems,% are rare and poorly integrated. Our analysis demonstrates the value of the few long-term, %legacy% data sets. Results suggest that differences in life history interact with complex disturbance histories, resulting in non-equilibrial dynamics in old-growth temperate tree communities, and that changes in disturbance patterns through anthropogenic climate change might, there%fore, be an important driver of ecosystem change

Multi‐decade tree mortality in temperate old‐growth forests of Europe and North America: Non‐equilibrial dynamics and species‐individualistic response to disturbance

Aim: Old-growth, mesic temperate forests are often assumed to be structured by gap-phase processes, resulting in quasi-equilibrial long-term dynamics. This assumption influences management focused on simulation of natural disturbance dynamics and is embedded in most models of forest successional dynamics. We use multi-decade monitoring of permanent plots in old-growth forests to assess demographic assumptions directly with respect to tree mortality rates. Location: Sixteen sites in mesic, temperate old-growth forests in eastern North America and Europe with multi-decade monitoring. Time period: Variable across sites, spanning c. 20%78 years from 1936 to 2014. Major taxa studied: Tree species of late-successional, cool-temperate forests of Europe and eastern North America. Methods: We calculated and compared the annualized mortality rates (m), with confidence intervals, by species, size class and measurement interval, for tree species of sufficient abundance. Results: Retrospective analysis shows dynamic and diverse demographic properties across populations and sites. Stand-scale mortality rates of 0.7%2.5%/ year average higher than previous estimates for old-growth temperate forests. Variations among species, over time and among size classes, suggest that gap-phase models are inadequate to explain stand dynamics, implying instead that rare disturbance events of moderate severity have long-lasting effects in old-growth forests and that indirect anthropogenic influences affect old-growth, unlogged forests. Main conclusions: Multi-decade baseline data, essential for understanding community assembly and long-term dynamics in these %slow systems,% are rare and poorly integrated. Our analysis demonstrates the value of the few long-term, %legacy% data sets. Results suggest that differences in life history interact with complex disturbance histories, resulting in non-equilibrial dynamics in old-growth temperate tree communities, and that changes in disturbance patterns through anthropogenic climate change might, there%fore, be an important driver of ecosystem change