Dorota Dobrowolska

Structure of silver fir (Abies alba Mill.) natural regeneration in the 'Jata' reserve in Poland

Over the last 20 years, investigations have been carried out to determine the influence of various ecological factors on silver fir natural regeneration in highlands and mountains. However, there has been little research on the structure and development of fir regeneration in lowlands. Results of this study indicate that three main stand characteristics play a very important part in the structure of fir regeneration in the lowland. The results revealed that the quantity, frequency and growth rate of fir regeneration were affected by site conditions. One of the most important ecological factors differentiating quantity and quality of fir regeneration was the proportion of fir in a stand. It was found that, with an increase in the percentage of fir in a stand, the quantity and the sum of heights and the sum of height increments of fir regeneration tends to increase. Results of this study showed that the number and development of fir regeneration were influenced by species composition of a stand; fir regenerated not only in pure fir stands but also in mixed forests. A positive influence of pine and birch canopy on initiation and development of fir regeneration was confirmed. Optimal conditions for the growth and development of fir with respect to species composition were found in mixed fir stands with an admixture of hornbeam. In contrast, results of the study suggest that the worst conditions for fir regeneration were found in the stands composed of species, such as ash, alder, oak, aspen, lime and spruce.

Climate change impacts in European forests: the expert views of local observers

Forests respond differently to changes in climate depending on individual site characteristics and tree status. Site conditions may buffer or boost impacts of heat, drought, and storm events. Considering contemporary changes in climate (Christensen et al. 2007), warming may increase forest productivity in those parts of Europe where growth resources like soil water are not limiting (Nabuurs et al. 2002). However, under conditions of limited resource supply and changed disturbance regime, we may expect a reduction of forest productivity and vitality (Lindner et al. 2010). Major climatic impacts on forests include both singular extreme events (changing climate variability) that are difficult to predict in time and location, as well as less obvious gradual changes (changing mean values) (Bolte et al. 2010; Reyer et al. 2013). This study presents an analysis of the diverse aspects of climate change impacts on forests in Europe based on the expert views of local observers. Local expert knowledge provides additional (often overlooked) information on climate change impacts and fills knowledge gaps for less-described European regions. Furthermore, we used expert knowledge to highlight a set of priorities for pro- and reactive forest management, taking into account differences and similarities among regions. Finally, we wanted to define “hot spots” of climate change impacts, i.e., regions, or selected tree species/stands in these regions, which are highly vulnerable and considerably exposed to negative impacts of climate change.

Ecology and silviculture of silver fir (Abies alba Mill.): a review

ABSTRACT Silver fir (Abies alba Mill.) is one of the most valuable conifer trees in Europe for historical and economic reasons. Growing interest in the species, along with the recognition that silver fir was subjected to inappropriate silvicultural measures during the 20th century due a lack of understanding of its ecology, have spurred recent studies from various disciplines which have yielded new insights into the gene ecology, history, ecology, structure and dynamics of fir populations. In this paper, we provide a multidisciplinary, synoptical review discussing the prospects for silver fir forestry in the 21st century. We describe the main characteristics of the history and ecology of silver fir, with a particular emphasis on gene ecology and the structure and dynamics of fir populations with respect to mixed stands and fir management. Fir is a fundamental species for maintaining high biodiversity in forested ecosystems because of its shade tolerance, plasticity to environmental conditions and ability to coexist with many tree species. Silver fir ecotypes show remarkable variation in features such as frost hardiness, drought resilience and shade tolerance. Fir can create stands of heterogeneous stand structure, from one-storied through to multi-storied structure and finally to selection structure. Natural regeneration of fir will be scarce if fir stands are managed inappropriately through the application of clear cutting, a short regeneration period and abrupt removal of shelter trees. Climate change is expected to reduce the abundance and distribution range of silver fir. Improvements in forest management treatments are recommended to improve silver fir conservation.

The Influence of Stand Structure on European Yew Taxus baccata Populations in Its Natural Habitats in Central Poland

ABSTRACT Taxus baccata is a rare species throughout its entire natural range and is often categorized as nationally threatened in countries where it occurs. In Poland yew is under protection and almost all sites with yew occurrences are subject to reserve protection. The aim of the study was to answer the following questions: What is the tree diameter structure of stands in three yew reserves? What is the stand biodiversity of three yew reserves in central Poland? How does the stand species composition influence natural regeneration of yew? What shall be done in the future to protect yew in its natural habitats? The study was conducted in three yew reserves in central Poland. Based on a detailed research on 30 circular sample plots established in each reserve we found high stand diversity in all investigated areas. Shannon-Weiner index (H´) was high in general and ranged from 1.50 to 1.69, and the Shannons index of evenness (E) ranged from 0.51 to 0.64. The diameter structure of two studied reserves was similar to natural multi-layered stand structure. The number of yew trees and their vitality was low. The species diversity of natural regeneration in all reserves was very high. However, the quantity and quality of yew regeneration in multi-layered diameter structure was significantly lower than in one-layered stand structure. To protect yew, appropriate conservation measures should be undertaken, including silvicultural treatments for in situ species conservation. We found that passive conservation is an inappropriate strategy for yew because of its weak competitiveness ability. We recommend active conservation approach, including silvicultural treatments. i.e. cutting broadleaved trees in places where the basal area is the highest, removing some trees in the upper layer of stand which compete with yews. Individual protection of yew seedlings and saplings is also necessary because of damages caused by herbivores.

Vitality of European Beech (Fagus sylvatica L.) at the Limit of Its Natural Range in Poland

ABSTRACT The European beech is a major component of central European forests, and the eastern limit of its range lies in Poland. However, the Holocene migration of the beech is not yet finished, especially in NE Poland, so the northern distribution of the beech continues to change. The main goal of this study was to determine if the beech will reach its northern limit in the future. The investigation was carried out in 18 beech stands in Poland. To study the status of the health of the trees, circular plots were established in grids of different sizes. The basal beech stand area ranged from 3.7 m2 ha-1 to 31.2 m2 ha-1. The density of trees exceeded a hundred trees per hectare in most of the plots (61%), and the average degree of defoliation was not greater than 60% in all of the investigated stands. Environmental conditions influenced defoliation of beech trees (Fishers test, F = 4.0204; P <0.0001). The vitality of the beech trees varied between stands (Kruskal-Walis test, H = 139.7433, P <0.0001) and was rather good in 56% of the study plots. Seedlings and saplings were observed in all of the investigated stands, and they covered from 5 to 39% and 21 to 80% of the study plots, respectively. Spontaneous beech regeneration was widespread and differed from stand to stand as well as within stands in all of the study plots. The number of tall seedlings in most of the study plots (56%) was greater than 10,000 individuals per hectare. The factors limiting beech regeneration were stand density and herb cover, and the number of beech seed trees influenced the quantity of small seedlings. Beech tree density positively influenced the number of small seedlings, and the strength of the correlation was moderate and statistically significant (Pearson correlation, r = 0.349). Beech tree density influenced the vitality of tall and small saplings (Pearsons correlations, r = 0.673 and r = 0.361, respectively). The spontaneous regeneration and strong vitality of seedlings and saplings suggests that beech can create stable stands in the future and that it is an expansive tree species both within its continuous range and at the limit of its distribution. It is quite possible that beech will reach its north-eastern limit in Poland in the future.

Stand structure and populations of yew (Taxus baccata L.) in the Cisy Rokickie and Bogdanieckie Cisy reserves

Abstract Yew Taxus baccata L. is an endangered tree species in parts of Europe. In Poland small populations grow in forest reserves. The study was conducted in two reserves established particularly for the protection of yew populations located in the region of Pomerania. The aim of the study was to know the number, vitality and growth conditions of natural yew regeneration and to identify threats to the regeneration of the species. The stand structure and regeneration of yew was described in 30 circular plots. The main tree species in stand canopy was Scots pine, however in Bogdanieckie Cisy beech also made up an important element of the stand. The density of yew regeneration was greater in Bogdanieckie Cisy than in Cisy Rokickie; the number of yew seedlings was 5000 individuals per hectare in Boganieckie Cisy and 3332 individuals per hectare in Cisy Rokickie. The vitality of yew regeneration was better under the beech-pine canopy in Bogdanieckie Cisy reserve than in Cisy Rokickie. Yew regeneration is grazed in the Cisy Rokickie reserve even though the fence. The forest floor influenced the amount of yew regeneration; the greater cover of herbs the lower the density of yew regeneration. The presence of yew in all phases (from seedlings to small trees) that regeneration processes continue in both reserves.