NORDIC VEGETATION SURVEY-A STATUS OF PROGRESS AND FUTURE OUTLOOK

<p><img title="lawesson_j.e._512" src="http://ojs.uniroma1.it//public/site/images/francesco_spada/lawesson_j.e._512.jpg" alt="lawesson_j.e._512" width="512" height="394" /></p&gt

QUERCUS FORESTS IN THE NORD IC COUNTRIES, A PRELIMINARY OVERVIEW

Quercus is remarkable for its wide ecological amplitude, occuring from mild, humid and oceanic settings on dunes and ledges to drier, cooler continental conditions on gravel, sand, clays and moraines. It most probably constituted a prominent component of all forests in Denmark previously, but are now mainly found on oligotrophic soils, much resembling the oak forests in the rest of the Nordic area. Only relatively few eutrophic oak forests remain intact, as Fagus sylvatica artificially has replaced oaks in many places in Denmark. A review of the principal Danish oak forest types is given, with notes on related types in Norway, Sweden and Finland

PHYTOSOCIOLOGY IN DANMARK

<p>As a contribution to the European Vegetation Survey, this paper reviews the development of phytosociology in Denmark. Phytosociology in Denmark was initiated by Warming and Raunkier in the 1890’s with the production of important papers on how to describe vegetation units and to measure them. The followed a long period of collection of vegetation data and development of data treatment methods, such as the similarity index by Sorensen in 1948. Few of the studies were strictly phytosociological, but rather informal floristic vegetation descriptions and ecological accounts, often with most emphasis on species-environment relationship. A few papers deal with community ecology and syntaxonomy, often a s apart of regional revisions. A stringent and consequent approach to describe plant communities in Denmark is much needed but yet to be adopted. An updated view of the past and recent types of plant communities and their ecology and status is badly need for any future planning of land use and conservation actions, management and monitoring.</p&gt

SYSTEMATICS AND ECOLOGY OF DANISH SALT MARSH COMMUNITIES

A review of salt marsh communities and submerged saline communities in Denmark is presented. A total of 24 communities has been recognised from published accounts of Danish salt marsh vegetation along with own investigations. A floristical classification based on TWINSPAN analysis of 696 relevées has been performed. For each community the existing knowledge on ecology, succession and impacts of management are summarized

PHYTOSOCIOLOGY IN DANMARK

As a contribution to the European Vegetation Survey, this paper reviews the development of phytosociology in Denmark. Phytosociology in Denmark was initiated by Warming and Raunkier in the 1890&rsquo;s with the production of important papers on how to describe vegetation units and to measure them. The followed a long period of collection of vegetation data and development of data treatment methods, such as the similarity index by Sorensen in 1948. Few of the studies were strictly phytosociological, but rather informal floristic vegetation descriptions and ecological accounts, often with most emphasis on species-environment relationship. A few papers deal with community ecology and syntaxonomy, often a s apart of regional revisions. A stringent and consequent approach to describe plant communities in Denmark is much needed but yet to be adopted. An updated view of the past and recent types of plant communities and their ecology and status is badly need for any future planning of land use and conservation actions, management and monitoring.</p

Species diversity and area-relationships in Danish beech forests

The vascular flora of 62 Danish beech forests of eastern Jutland ranging in size from 1-445 ha, was investigated for species-area relations. Species richness reflecting total diversity, forest diversity, and of different habitat groups, were corrected for non-linearity by means of a log-log power function transformation and regressed to forest area. The transformed forest species diversity showed a negative relationship with forest area. It is highly questionable whether the often stated positive correlation between forest area and species number is valid when the total species numbers are corrected for the area-error. The often stated theorem that the larger the forest, the smaller the disturbance, is not valid in Danish broad-leaved forests. On the contrary, if the number of ruderals is taken as an indication of human disturbance, the correlation of area with the proportion of ruderals to all species and to forest species, both failed to detect correlation with area. This is probably due to the less intensive management regimes in small forests compared with larger forests. A substantially larger number of forest species is found in ancient forest than in middle-aged forest. This shows the great importance of forest continuity for the species diversity. Lists of indicator species for ancient and old broad-leaved forest are presented. The corrected species diversity value is recommended as a good nature quality indicator, to be used in comparative studies and for assessing biological quality for management and conservation actions