Regeneration dynamics in an alluvial dense ash (Fraxinus excelsior L.) stand

Broadleaves regeneration dynamics and the succession mechanism were studied within a transect of 14 m x 56 m in a dense 80-year-old ash stand situated on an alluvial soil. For this purpose, abundance and height of all naturally regenerated species at different development stages were analyzed and their distribution over the juvenile and older growth stages determined. The study reveals that from the main broadleaved tree species, Quercus robur and Fagus sylvatica regeneration scarcely occur at any growth stages. No Fraxinus excelsior regeneration, except 1 unit, taller than sapling (1.5-4 m) can be found on this soil type. On the contrary, Acer pseudoplatanus represents different development stages (seedling, sapling, thicket, small pole and large pole) and in stand patches where an understorey is practically lacking, its regeneration is well developed. Results generally show that at the juvenile and older growth stages Acer proceeds Fraxinus and regeneration is largely dominated by the invasive Acer. It is expected that this succession process will continue and that Acer will overcome in the overstorey and even gradually form an almost single-species dominating stage. Direct interventions are unavoidable in order to regulate the primary mixture patterns.

Distribution of soil moisture content and its effect on the potential growth of the over-story species in North-East Chalkidiki

This study deals with the soil moisture distribution and its effect on the potential growth and adaptation of the over-story species in north-east Chalkidiki. These species are: Quercus dalechampii Ten, Quercus conferta Kit, Quercus pubescens Willd, Castanea sativa Mill, Fagus moesiaca Maly-Domin and also Taxus baccata L. in mixed stands with Fagus moesiaca. Samples of soil, 1-2 kg per 20cm depth, were taken and the moisture content of each sample was measured in order to determine soil moisture distribution and its contribution to the growth of the forest species. The most important results are: i) available water is influenced by the soil depth. During the summer, at a soil depth of 10 cm a significant restriction was observed. ii) the large duration of the dry period in the deep soil layers has less adverse effect on stands growth than in the case of the soil surface layers, due to the fact that the root system mainly spreads out at a soil depth of 40 cm iii) in the beginning of the growing season, the soil moisture content is greater than 30 % at a soil depth of 60 cm, in beech and mixed beech-yew stands, is 10-15 % in the Q. pubescens stands and it's more than 30 % at a soil depth of 60 cm in Q. dalechampii stands.

Aspects of biodiversity of Scots pine forests in Europe

Management of Scots pine, the most widely distributed conifer in the world, was often based on clearfelling and replanting regimes, resulting in a rather poor biodiversity value. However, there is nowadays a general expectation to increase biodiversity by applying a more complex silviculture. Although present knowledge of genetic factors is insufficient to draw firm conclusions on the desirable level of genetic diversity, it seems unlikely that current silvicultural practices will limit genetic diversity in Scots pine Native pinewoods are rare in Europe, but have a flora and fauna of high conservation value. Therefore they must be recognized as a priority habitat under the European Commission's Habitat Directive. The high conservation value of native stands is a function of their old-growth structure that provides a rare habitat. A number of measures should be taken in all types of Scots pine forests to enhance biodiversity. Firstly, old growth habitats should be promoted. Foresters have to accept that a small percentage of the pine resource should be managed upon much longer rotations. Secondly, retention of deadwood should be encouraged. Dead and dying wood are key components of stand structure and act as key substrates for many associated species, such as microbes, invertebrates, small mammals and birds. Furthermore, a complex stand structure should be promoted at both the horizontal and the vertical scale. A small scale forestry, group regeneration systems, natural regeneration, introduction of broadleaves and stronger thinnings are strongly recommended. Availability of quite precise niches significantly increases biodiversity value. Conservation of isolated populations, found under extreme environmental conditions, is an absolute need. Populations endangered either by their small size or by environmental stresses, hybridization with other species or human interference should be primarily conserved. Forest edges support a range of taxa, and open habitats can comprise many different plant community types. A large number of organisms are directly or indirectly dependent on or favoured by fire. However, enhancing biodiversity provokes also some risks. Generally, browsing is considered as a moderate risk. Introduced species, such as aspen, act as an alternate host to the rust. Open species can present a threat to the European pine marten, dying and deadwood can provide breeding habitats for pest species (Tomicus piniperda), burning increases the risk of seedlings being attacked pine fire fungus (Rhizina undulata) and forest edges may be an attractive habitat for pest insects. An extension of existing growth models is needed to incorporate biodiversity issues in forest management planning. Distance dependent individual tree growth models should be developed. Sets of indicators for biodiversity must integrate compositional, structural and functional attributes. Attributes such as species richness, species abundance, species diversity, horizontal and vertical distribution, tree age, tree size, stand diversity, architectural complexity, genetic variants and deadwood are needed for the establishment of biodiversity indices. Assessment of functional phenomena needs the knowledge of the driving biotic environmental factors.

Experiences with participatory approaches in the forestry field in Flanders

Participation into the forestry decision making is in Flanders not to be considered as a real new fact. A number of important forestry topics can be mentioned; whereby participation played a role: (1) forest legislation and forest policy; (2) management plans; (3) National Forest Plan; (4) criteria for sustainable forestry; (5) the Spatial Structure Plan Flanders; (6) establishment of urban forests. The Forest administration, the Flemish Supreme Forestry Council, forest owners, forest associations and scientific institutes are well known internal actors, whereas the agricultural sector and the nature conservation sector are the most salient external actors. However, a distinction must be made between participation and external pressure. Real participation supposes that it is institutionalized and that it is considered as a normal fact. Today, the pressure behind the screen is very great and the real decision making obviously occurs there. At least the impression exists that external actors such as the economic sector, the nature sector and the agricultural sector, which are often not directly involved in the forest decision making, pIesently ore determine many forest policy topics than the forestry sector itself. Besides, participation is not a priori a basis of success.

Structure and development patterns analysis of Fagus sylvatica s.l.- Quercus dalechampii Ten. stands in two areas in the Rhodope mountains of Xanthi region

This study was conducted in Fagus sylvatica-Quercus dalechampii stands in two areas in the Rhodope mountains of Xanthi. In order to analyse the structure and the development patterns of our stands, 23 plots were established, increment cores were taken, and stem analysis was conducted in 2 couples of dominant (competitive) beech and oak trees. The main results of this research indicate that a) In the mountainous part of the study area, natural and anthropogenic disturbances form the initiation, development and structure of beech-oak stands. However the fact that a number of oak trees survived after the disturbance in combination with landscape topography, which inhibited the dispersion of pine seeds, the species biology and the local climate, which is warmer than that of adjacent areas, influenced the succession pathways in the area and allowed oak to act as a pioneer species. b) Even though only one of the two structural types, tound in the submountainous part of the study area, was initiated by (anthropogenic) disturbances, the structure and composition of both structural types stands were and still are formed by illegal cuttings in which the oak wood is preferred. c) In both competing couples, the beech trees, after the first 80-85 years of their life, showed by far higher volume growth rates than the adjacent competitive oak trees which, in combination with the trees height growth patterns, implies, that in the future, a total domination of beech trees (in the two couples) will be observed. d) Forest practice must preserve the mixture of beech and oak in the mountainous part of the study area and enhance the presence of oak component in the submountainous part of the study area, in order to maintain· the diversity of these stands, to avoid the disadvantages of a homogenous forest and to mediate an orderly transition of community types, if the predicted increase in the average global temperatures comes true.

Long Term Plan Forestry and Action Plan Forestry in Flanders

In Flanders, the first serious regulations to set up a "National Forest Program" (NFP) were taken by the Forest Act in 1990. Consequently, a comprehensive scientific study and analysis of the forest and forest policy were carried out. A first Action Plan Forestry was drawn up in 1994, but it never got a legal character. The Flemish Environmental Policy Plan of 1977 insisted to set up an Action Plan Forestry. In 1998 the Flemish Forest Service launched two documents: the "Long Term Plan Forestry" and the "Action Plan Forestry". Together they were considered as the Flemish National Forest Program, in accordance with the recommendations of the International Panel on Forestry. However, although approved by several advice committees, these documents have never been legally approved. The Long Term Plan Forestry is based on four touchstones: sustainability, multiple use, international developments and commitments, and social support. In this frame four key notions are distinguished: forest maintenance quantitatively, forest maintenance qualitatively, forest extension, and integrated task fulfillment. To concretize this plan an Action Plan Forestry with 29 actions and 19 regulating initiatives was launched. The objectives of both action plans were only partly implemented. The too ambitious program was probably the most important reason. The great challenge in Flanders is to legally approve an NFP. It is clear that such a program can only be approved when its ambitions are not too high, so that the interest of other sectors are not directly threatened. The value of such a minimal NFP is, however, very limited. Therefore it is probably better to draw up regularly an ambitious, actualized and well founded forestry document, which is not legally approved, but with a high moral value.

The mixed forests of Greece

Greece is a mountainous Mediterranean country characterised by a variety of microenvironments. As a result, a great number of mixed forest types appear. These stands are natural by unevenaged stands with a lot of ecological and social advantages (as resistance against biotic and abiotic factors) high biodiversity and aesthetical beauty. For this reason, these forests must be protected and managed in a sustainable way, in order to fulfil their valuable services. This paper is dealing with the most important and representative mixed-species stands of Greece beginning from those existing in the lower elevations (zone of evergreen broadleaves) and continuing to the higher ones (zone of boreal conifers).

Results of a forest species trial in an arboretum of North Greece

This study deals with the survival, growth and silvicultural characteristics of some exotic, Mediterranean and native species planted in the Vassilika Arboretum, North Greece (South Europe) under Mediterranean climatic conditions. The results obtained 25 years after trial establishment showed that, from the ten species planted only the native species Pinus halepensis, Pinus brutia, Cupressus sempervirens and to a lesser extent Pinus pinea and one east Mediterranean but not native in Greece Cedrus libani, managed to show a good result. The fast growing exotic species (Pinus radiata, Eucalyptus globulus) showed good growth in the early years, but a low survival rate after 25 years. Species outside of the floristic zone Pinus nigra and Pinus sylvestris presented very low growth and finally died due to harsh climatic conditions.

Die Tätigkeit des Flämischen hohen Forstrates

Die Aufgaben des Flämischen Hohen Forstrates werden hauptsächlich durch das Forstgesetz bestimmt, teilweise auch durch das Naturschutzgesetz. Er soll nicht nur den Minister und die Forstverwaltung in der Forstpolitik beraten, sondern sich auch mit der Behandlung des Waldes in verwandten Politikbereichen beschäftigen. Die Hälfte der Mitglieder müssen Waldbesitzer oder Vertreter von Waldbesitzern sein. Der Rat formuliert eine Vielzahl von Stellungnahmen. In den Jahren 1997, 1998 und 1999 standen die folgenden Themen im Vordergrund: das flämische Forstgesetz, Kriterien für nachhaltige Waldwirtschaft in Flandern, die langfristige Forstwirtschaftsplanung und der Aktionsplan Forstwirtschaft, das Naturschutzgesetz, die Raumordnung, das Verhältnis zwischen Naturschutz und Waldsektor, Bewirtschaftung von Privatwäldern, Waldgruppierungen (Zusammenschlüsse von Waldbesitzern), Erbschaftssteuer für Waldflächen und die künftige Waldpolitik. Eine Evaluation des Rates ergab eine Reihe von Stärken und Schwächen. Die Sitzungen des Rates finden sehr häufig statt. Er hat eine besondere Aufmerksamkeit für Berührungspunkte mit verwandten Sektoren und Angelegenheiten. Trotz einer gewissen Dominanz der Privatwaldbesitzer sind die Stellungnahmen ziemlich ausgeglichen. Ein besonders positiver Punkt ist, dass er im hohen Mass zur Mitwirkung der Basis beigetragen hat. Die Kapazität innerhalb des Rates ist jedoch nicht immer ausreichend. Es zeigt sich, dass der Minister und die Forstverwaltung die Stellungnahmen des Rates nicht sehr hoch scnätzen. Der direkte Einfluss des Rates auf die Forstpolitik und auf die Politik von verwandten Sektoren ist eher beschränkt.

Dynamics and development patterns of Pinus sylvestris L. - Fagus sylvatica L. stands in Central Rhodope

The study was conducted in second growth stands in the central Rhodope mountains and (specially) in the region of Xanthi. In order to determine the dynamics and the development patterns of Pinus sylvestris - Fagus sylvatica stands, 39 plots were established, trees were cut, increment cores were taken, and stem analysis was conducted in 4 couples of dominant (competitive) pine and beech trees. The main results of this research indicate that a) The population structures, the regeneration and development patterns are strongly influenced by human and natural disturbances and species 'life history characteristics'. b) The difference in site quality between site types results in differences in the duration of beech invasion (under pine) and in species basal area distribution. c) In good site qualities when individual dominant beech and Scots pine (competitive) trees with a small age difference grew together, the beech trees, in some cases, have almost the same height growth as the pines and the pine trees showed a delayed (for the species) culmination in current annual volume increment which is not followed by a abrupt fall. d) The process of secondary succession is influenced by disturbances regime, environment, propagule availability and species biology.