Funded: Austrian Academy of Science - UNESCO programme "Man and the Biosphere"
|Projectleader:; Prof. G Grabherr|
|Coworker: G. Koch, H. Kirchmeir, K. Reiter|
|Collaboration:Federal Ministry for Agriculture and Forestry, Austrian Federal Forestry Research|
The term hemeroby was introduced to botanical terminology approx. 25 years ago and it has appeared in several scientific writings as a complementary term for "naturalness" ever since. These considerations were initiated by the observation that a significant number of plant species - this also holds true for animal species - in the agricultural landscapes of Europe are strongly influenced by and act as indicators of the intensity of agricultural and silvicultural utilisation. The Finnish botanist JALAS (1955) chose the term hemerochora which the German ecologist SUKOPP (1972) applied to entire ecosystems and attempted to describe the various intensities of agricultural utilisation by employing defined attributes.
In principle the concept of hemeroby is generally applicable and free of any connotations. The term hemeroby is exclusively used in scientific literature and thus less likely to be confused than the term "naturalness". This was the reason when assessing the naturalness of Austria's forests and forest ecosystems in general, that we decided to start from the other end by describing the situation of forests characterised by different intensities and modes of utilisation in hemeroby levels. Based on a very clear picture obtained from 4892 field samples to which assessment criteria were applied, it was finally decided to attempt a linguistic classification for naturalness levels in an expert group of ecologists and forestry specialists, based on hemeroby assessment. The classification terms agreed upon were "artificial", "altered", "moderately altered", "seminatural", "natural". The extensive final report on the project will describe these naturalness levels and explain graduations in detail.
The situation, however, can be best described with pictures. This was the motive for creating this small illustrated book. For every naturalness level, different stages are presented. Naturalness in a pine forest differs from naturalness in a spruce-beech forest. Strong external influence can also be determined on the basis of the composition of the tree layer and the understory or even by the age structure of the stand. In other words, the stage of the individual attributes used in the hemeroby or naturalness assessment can be made up quite differently for one and the same naturalness level. This is the reason why several pictures are provided for each level.
Occupying 46,2 % of the country's surface or 3.88 hectares of land (1994 Forest Report), the "forest" type of cultivated area is the most significant landscape element in terms of quantity. The question therefore often arises: to which extent or intensity has man influenced the forest ecosystem and how natural are the forests of Austria today?
Up to this day, this could not be answered at all or at best on the basis of subjective criteria. The research project "The hemeroby of Austrian Forest Ecosystems" was launched in 1992 through an initiative of the department for vegetation ecology and nature conservation research at University of Vienna and the Academy of Sciences in order to provide an answer to this question founded on scientific facts. This project is part of the international research initiative of the UNESCO programme "Man And The Biosphere".
The project was co-ordinated with the Federal Ministry for Agriculture and Forestry and a close collaboration with the Austrian Federal Forestry Research Institute (Forstliche Bundesversuchsanstalt) developed and investigations were carried out at their sample points. The project team members are pioneers in the first assessment of the naturalness of large forest surfaces world-wide. Within this context, the co-operation of nature conservation research on university level and a practice-oriented federal research institute under the auspices of the Academy of Sciences and the Federal Ministry for Agriculture and Forestry also deserves honourable mention.
In order to assess the naturalness of Austrian forests, the effects of wood cropping, forest pastures, hunting, tourism, and other forest uses on domestic forests were analysed. The anthropogenic influence on forests was determined on site for specific forest crops using reconstructible criteria, and a geographical distribution with varying degrees of naturalness or hemeroby was calculated on the basis of over 2 million data records. All data was stored in an information system with reference to geographical position (geographical information system).
Area of investigation and objectives
The area of investigation comprised the entire forest area of Austria which was studied on the basis of 4892 representative sample plots. The description units are forest-districts or forest ecoregions according to MAYER (1974) and KILIAN et al. (1994). The objectives set for the project were:
Method and concept of hemeroby
According to KOWARIK (1988), hemeroby is "a measure for man's cultivation influence on ecosystems, whereas assessment of hemeroby level is carried out based on the extent of effects of those anthropogenic influences which affect the system's development towards a final state".
The central issue is: "Which forest population does the current site support?". This is a new approach meaning that the current site conditions are used as the starting point for the analysis of man's influence on an ecosystem. The reference value (set value) of hemeroby assessment is the "potentially natural forest population" (HÄRDTLE 1989, POTT 1993, a.o.). This means the composition of species that would develop under the current environmental and site conditions if man no longer intervened and vegetation had time to develop up to its final state.
This study combined trend-setting work on hemeroby (BLUME & SUKOPP 1976, KOWARIK 1988) with detailed scientific approaches of ecological forest assessment (AMMER & UTSCHICK 1984, a.o.).
This led to the development of a special catalogue of criteria for assessing the hemeroby (or naturalness) of forests. The basis of data collection on the field are uniquely ascertainable and reconstructible individual criteria such as "naturalness of tree species", "naturalness of ground vegetation", "amount and quality of dead wood", "degree of exploitation", etc. as illustrated in Fig. 1
The naturalness levels are composed of links between 18 individual criteria (hemeroby levels) such as "naturalness of the combination of tree species", "naturalness of ground vegetation", "dead wood volume", "intensity of human exploitation", etc. These parameters were measured on the sampling areas and subsequently converted into an ordinal scale from 1 (artificial) to 9 (natural). In order to facilitate practical use, the levels were condensed to 5 naturalness levels which are represented in the present book by pictures of typical forest stands. The conversion of the values collected (solid measure of dead wood, vertical structure, etc.) in a relative value enable a pair by pair linking of the criteria to a hemeroby value (Fig. 1). This method of evaluation makes it easy to test and derive the hemeroby value and renders the procedure comprehensible and transparent.
The naturalness levels are composed of links between 18 individual criteria (hemeroby levels) such as "naturalness of the combination of tree species", "naturalness of ground vegetation", "dead wood volume", "intensity of human exploitation", etc. These parameters were measured on the sampling areas and subsequently converted into an ordinal scale from 1 (artificial) to 9 (natural). In order to facilitate practical use, the levels were condensed to 5 naturalness levels which are represented in the present book by pictures of typical forest stands. The conversion of the values collected (solid measure of dead wood, vertical structure, etc.) in a relative value enable a pair by pair linking of the criteria to a hemeroby value. This method of evaluation makes it easy to test and derive the hemeroby value and renders the procedure comprehensible and transparent.
Sample selection and field investigation
In selecting the samples, a combined method of systematic matrix and stratified random sample selection was used. Exclusively environmental criteria were taken into consideration for stratification, such as elevation, climate, forest ecoregion, or exposure. The selected samples coincide with the matrix points of the Austrian Institut für Forstinventur. One sample consists of an area of 625 m² on which the set of criteria was applied and inventory of the vegetation (see Fig. 3) was taken according to BRAUN-BLANQUET (1964). By coupling the hemeroby field investigation with the sample points of the Austrian Institut für Forstinventur, the results of this study can be linked to several data of the Federal Forestry Research Institute.
Out of a total forest area of ca. 3.88 million hectares, more than 20% can be classified as seminatural or natural, whereby these terms are used in a very strict sense. "Natural" means "without human impact". Despite the presence of historical influences these are no longer discernible today. These forest zones are located mainly in the Inner Alps and the Northern and Southern Limestone Alps. The remarkably high proportion of zones classified as seminatural comprises weakly exploited forests featuring a natural blend of tree species with low perturbations to ground vegetation and forest structure. The proportion that clearly ranks first are moderately altered forest zones. These forests are all exploited, however, at least some residual natural vegetation remains. The structure of the forest stand such as vertical structure or age has been distinctly altered by wood cropping and forest pasture practices. Approximately one third of the entire forest area is considered altered or artificial. These areas are heavily exploited and the composition of tree species no longer corresponds to natural conditions. These forests are often dominated by non local tree species.
The percentage of seminatural or unnatural forest areas varies greatly from province to province. Provinces featuring a high percentage of inner alpine mountain forests and a historically shaped farmer-tended forest structure boast the highest percentage of forests described as seminatural (Vorarlberg, Tyrol). Particularly Vorarlberg has a long-standing tradition of nature-adjusted wood cropping on a small area. Provinces with a high proportion of easily accessible forest areas (low cost development) and mixed forests have a high share in forest areas described as unnatural or artificial since the economically important spruce species does not occur or only rarely occurs there naturally and conifers, even exotic locally, were chosen for reforestation.The collection of data on individual forestry enterprises is not possible with the sample selection applied.
All data was stored in an information system with reference to geographical position (geographical information system). In the future this data shall be available for answering other scientific and practical questions.
Map: Hemeroby of Austrian forest Ecosystems