Published in Colloques Phytosociologiques, 23: 473-485

IAVS Symposium "Large area vegetation surveys", Bailleul 1994

FOREST CONDITIONS UNDER THE AIR-POLLUTION IMPACT IN EUROPE (SOME RESULTS OF THE INTERNATIONAL CO-OPERATIVE PROGRAMME)

Matějka Karel

Etat des forêts sous l'influence des polluants atmosphériques en Europe (guelques résultats du programme international)

Le programme de la coopération internationale (ICP Forests) représente le projet paneuropéen fondamental de surveillance de l'état des écosystèmes forestièrs. Dans le cadre de ce programme on prêt attention principale à l'état (degrée de detérioration) des arbres, à quelques propriétés des terres, à l'état de la nutrition des peuplements forestièrs, à la charge des écosystèmes forestièrs par la pollution atmosphérique et aux rapports phytocénologiqes. Cette qustion dernière, il faut la solver sur la base plus générale de la classification des associations végétales des forêts cultivées. Les résultats présent‚s proviennent du traitment des trois ensembles de données établis en République Tchèque. Pour la sélection des données ont été adoptés les procédés de la classification et ordination numérique.

Forest conditions under the air-pollution impact in europe (some results of the international co-operative programme)

The international co-operative programme on assessment and monitoring of air pollution effects on forests (ICP-Forests) is a basic project of the forest state monitoring. It includes the investigation of tree health state (degree of damage), some soil properties, level of nutrient availability using foliar analysis, air pollution loads of forest ecosystems, and plant coenology. The last topic is necessary to solve within more common base of the man-influenced forest classification. Results presented in this paper reflects an analyse of three data sets from the Czech republic. Used approach consists in numerical processing (classification and ordination) of relevés.

DEVELOPMENT OF THE FOREST MONITORING PROGRAMME

Deterioration of the health state of forest stands in different countries within Europe called out the necessity of an evidence of negative changes in stands. Single determination of the state has been changed gradually into the system of repeated investigation - some monitoring systems have been developed and applied. The system developed in the Czech Republic has been probably the first one. This priority was called mainly by the fact that in late fifties and early sixties a great number of forest ecosystems in higher altitudes, disturbed by air pollution, have been observed. From Central Europe the situation spread gradually, and with different intensity, to other parts of the continent. The other factors with adverse effect on forest health status and destabilisation of forest ecosystems followed.

In different climate zones diverse problems have been observed. In Scandinavia it has been a chronic acidification (e.g.

The necessity of the unified system of monitoring of forest health state developed within Europe. The impact of air pollution was the basic unifying factor. So called "Fichtelgebirge-project" in Germany (Schulze, Lange, Oren, 1989) ran in time of the unification of approaches in different countries. The project is today nearly the classic one. In similar position is the Polish project of influence air pollution on forest vegetation (Grodzinski et al., 1984).

The monitoring activities of investigation on forest health state have been developed within the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP-Forests) of the Economic Commission for Europe of the United Nations (UN/ECE), in a close collaboration with the Commission of the European Communities. Following the first Strasbourg Resolution of the Ministerial Conference on the Protection of Forests in Europe, the signatory states are obliged in participating on the ICP-Forests programme (for details see LANDMANN, 1993). Three basic study levels have been defined (PCC-West, PCC-East, 1994):

• Level 1 - Large representative survey and assessment,
• Level 2 - Intensive studies on permanent plots,
• Level 3 - Special forest ecosystem analysis.

This paper will be dealing mainly with two issues - examples of some ICP-Forests results and a linkage the monitoring programme and plant coenological studies on man-influenced forests in the Central Europe.

PRESENTATION OF THE ICP-FORESTS

The estimation of defoliation (loss of needles/leaves) is the basic parameter of the investigation of tree health status. The estimation is provided with the accuracy 5% on chosen permanently signed trees. The evaluation of the whole stand is based on counting of average defoliation and/or assessing the share of trees with certain (low or high) defoliation degree. Following classes of defoliation are commonly used for all tree species (originally defined for Norway spruce):

The survey in Table 1 shows the development of defoliation within Europe and especially in Czech Republic during the course of ICP-Forests. All European results follow the year-to-year reports the last of which was published byUN-ECE, CEC (1994).

Together with defoliation observing also the properties of soil and the tree stand nutrition are investigated. The study of forest soil is concentrated on content of some chemical elements, mainly nutrient and heavy metals.

Similarly the investigation of nutrition status and environmental load, based on foliar analysis is realised. The data for the Czech Republic show that results of such analysis can be used also to delimitation regions of specific nutrition/load. Sampling has been done in 1991 in young spruce stands. Nutrients (N, P, K, Ca), heavy metals (Pb, Cd, Cr) and some other elements (S, Na, Al, Fe, Mn, Zn, Cu) have been determined. The first to fourth needle-year-classes have been analysed. The data were processed using multivariate statistical analysis (PCA). The description of behaviour of different elements in different needle-year-classes and their correlation are the basic results (compare Figs. 1-2). The first needle-year-class and second one are very similar in the correlation structure of the element contents. A parallel similarity exists between the third and fourth needle-year-class. It has been shown, that possibility of investigation of the nutrient status is better on the base of the first or second needle-year-class. In contrary the environment load can be monitored on the base of third and/or fourth ones. Some areas with distinct element composition in needles of the first year class were drafted on the basis of 1st and 2nd ordination axes (e.g. Fig. 3.).

Several countries (including the Czech Republic) suppose the plant-coenological investigating within the study plots network as a basic part of study in the level 1. There is clear evidence of importance of the plant coenological studies within forest damage investigation (e.g. Medwecka-Kornas, Gawronski, 1990; Tyler, 1987; Wojterski, 1990). In the frame of ICP-Forests, a set of relevés have been gathered. It is necessary to evaluate this set. The classification of the material collected has to be done at the first stage. The classification could help also e.g. in more detailed specification of different forest-vegetation units with different type and degree of damage. However, in Central Europe there is one urgent problem - up to data only few authors have been dealing with phytocoenology of managed (man-influenced or man-made) forests, mainly forests of changed species composition of the tree layer.

SYNTAXONOMY OF THE MAN-INFLUENCED FORESTS IN CENTRAL EUROPE

There are a lot of systems to use in forestry applications and forest coenology (see Jahn, 1982). They are based largely on a classification of environmental conditions regarding to the potential vegetation. Many coenological papers deal only with natural forest communities. Real contemporary situation in the Central Europe call for another approach.

The study of Hadač and Sofron (1980) is among the few in Central Europe, concentrated on syntaxonomy of man-made forest communities. The authors clearly showed on examples that in man-influenced forests stabilised processes occur. It heads towards the creation of relatively stable species combinations useable for distinguishing the coenological unit system. It is obvious, that names as Senecioni fuchsii-culti-Piceetum and Deschampsio flexuosae-culti-Pinetum are not valid from the viewpoint of the nomenclature code (Barkman, Moravec, Rauschers, 1986). They do not meet the principle stated in Article 34 of the Code.

Not taking in account presented communities with locust tree, following system of the man-influenced forests can be presented:

Luzulo-Fagion Lohmeyer et Tüxen in Tüxen 1954

Senecioni fuchsii-culti-Piceeetum Hadač et Sofron 1980

Vaccinio-Piceion Br.-Bl. 1939

Avenello flexuosae-Piceetum Hadač et al. 1969

Vaccinio myrtilli-Piceetum Sofron in Hadač et Sofron 1980

Oxalido-Piceion (Krajina 1933) Březina et Hadač 1962

Oxalido acetosae-Piceetum (Krajina 1933) Březina et Hadač 1969

Pino-Quercion Medwecka-Kornas, Kornas, Pawlowski 1959

Deschampsio flexuosae-culti-Pinetum Hadač et Sofron 1980

Vaccacinio myrtilli-culti-Pinetum Hadač et Sofron 1980

Numerical syntaxonomy is useful tool in forest stand classification (e.g. Makirinta, 1990;Tonteri, Hontanen, Kuusipalo, 1990). The numerical analysis (cluster analysis [method SSC/ED], detrended correspondence analysis; both procedures using data of the original Domin-Hadač's scale of species coverage, data transformed into average percentage coverage and with presence-absence data) of the herb layer of 33 plant coenological relevés presented by Hadač andSofron has been done (Figs. 4-5). The results confirming the problem of differentiation of associations are described. It is obvious that problems can occur mainly within acidophilous man-influenced forest with Avenella flexuosa and Vaccinium myrtyllus, and also with the border between communities with Oxalis acetosella (sometimes classified within the above-association units of natural forest communities) and communities of the coniferous stands with Senecio fuchsii with open canopies. In material analysed there is only a few examples of the stands with minimal cover of herb layer. A lot of stands with absence of herb and moss layers make the real situation more complicated.

In South Bohemia a study has been done by Matějka (1993), presenting associations to which the samples analysed could be assigned as the man-influenced forest variants:

Alno-Ulmion Br.-Bl. et Tüxen ex Tchou 1948 em. Th.Müler et Görs 1958

Arunco sylvestris-Alnetum Tüxen 1957

Carpinion Issler 1931 em. Mayer 1937

Stellario-Tilietum Moravec 1964

Tilio-Acerion Klika 1955

Lunario-Aceretum Schlüter in Grüneberg et Schlüter 1957

Fagion Luquet 1926

Eu-Fagenion Oberdorfer 1957 em. Tüxen in Tüxen et Oberdorfer 1957

Dentario enneaphylli-Fagetum Oberdorfer ex W. et A. Matuszkiewicz 1960

Galio-Abietenion Oberdorfer 1962

Abieto-Quercetum Mráz 1959

Alnion glutinosae Malcuit 1929

Carici elongatae-Alnetum Koch 1926

Genisto germanicae-Quecion Neuhäusl et Neuhäuslová-Novotná 1967

Luzulo albidae-Quercetum (Hilitzer 1932) Passarge 1953

The new association Avenello flexuosae-Pinetum sylvestris Matějka 1994 within alliace Dicrano-Pinion Libbert 1993 has been described. This syntaxon represents a secondary plant community of the man-influenced forests with Scots pine on acid soils without any influence of high water level. Avenella flexuosa and Vaccinium myrtillus are the dominant plant species. Some communities with Norway spruce show a similar structure. The unit is wide comprehended. This approach helps to solve the problem mentioned by analysing the paper of Hadač and Sofron (1980).

However, a great part of the material remains unclassified in practice. The classification of the whole set of relevés has been done with the use of mathematical methods. Five basic groups of community types of man-influenced forests of the region investigated have been assigned using the procedure TWINSPAN:

1. Stands of the alliance Dicrano-Pinion as secondary man-made stands of Scots pine or Norway spruce in 3rd (oak-beech) or 4th (beech) forest vegetation altitudinal belt (FVB),
2. Man-influenced forest stands of less changed species composition of trees in (mainly) 3rd FVB,
3. Forests of different degree of species composition change on rich soils,
4. Less changed forest stands of the 4th FVB in the suballiance Eu-Fagenion or the alliance Tilio-Acerion,
5. Hygrophylic forests of the spring areas and the floodplain sites.

Also specific environmental conditions and structural characteristics of investigated types of groups have been mentioned (Matějka, 1993). In a more detailed scale, "community types" without syntaxonomic specification have been used.

Another sample material has been collected within the whole area of the Czech Republic in the frame of ICP-Forests. Part of it, Hadač's relevés, and the set to be discussed above (Matějka, 1994) were analysed together by multivariate statistics. The basic results are interpretable in next points (compare Fig. 6.):

• There are possibility of a good delimitation of the association Avenello flexuosae-Piceetum Hadač et al. 1969, Avenello flexuosae-Pinetum Matějka 1994 (both var. typicum and var. with Vaccinium myrtillus), and man-influenced forests of association Luzulo albidae-Quercetum (Hilitzer 1932) Passarge 1953 var. with Calamagrostis arundinacea.
• An existence of the association Senecioni fuchsii-culti-Piceetum Hadač et Sofron 1980 is not well founded for its heterogeneity.
• There is a possibility belonging of the communities named Oxalido acetosellae-Piceetum Březina et Hadač 1969 to various syntaxa. A meeting of this stands with the original diagnose of natural mountain community (Hadač et al., 1969) is discussible.

• Man-influenced communities with Fagus sylvatica (Carpinus betulus, Acer pseudoplatanus or Alnus glutinosa) shows small differences comparing natural ones. It is one of reasons for classification they into syntaxa of natural forests in a form of degradation stadia.
• The group of man-influenced forests growing in 3rd to 5th forest-vegetation altitudinal belt (oak-beech to spruce-beech belt) without influence of under-ground water level in the active soil horizons is very heterogeneous, their classification is most problematic. Base on their instance an idea of classification of the man-influenced forests is viable to introduce. This idea consist in a combination both the classification of natural forests and the classification of changes (not only community structure but also environment).

Surveying the list of higher vegetation units on the area of the Czech Republic (Moravec, 1983), only three units have been mentioned in connection with man-influenced forest stands:

• alliance Luzulo-Fagion Lohmeyer et Tüxen in Tüxen 1954 (with comment 'on the nutrient rich soils as a secondary degradation stadia following herb rich beech and silver spruce-beech natural forests'),
• alliance Dicrano-Pinion Libbert 1933 (with comment 'Scots pine forests on the sandy soils embrace secondary stands, too'),
• class Robinietea Jurko ex Hadač et Sofron 1980 (communities of man-made locust stands).

Roo-Zelinska and Solon (1990) have published a paper to the typology and coenology of Polish man-influenced forests with oak and larch, prevailing young stadia. Unfortunately, a proper data set - relevés are missing.

Detailed study on vegetation in all sample plots of ICP-Forests has been done in Austria (Karrer, 1992). The total of 513 samples presented. Nevertheless, the syntaxonomical classification is up to data minimal. In the work cited, there are less than two pages dealing with it. Any syntaxon has not been named.

CONCLUSIONS

At the end it is necessary to stress, that several parallel approaches to the classification of man-influenced forest communities can exist. The first stage should be concentrated on determining of basic types of communities, not considering the phytocoenological system. It can be expected, that some of types can be described as associations, Their development is man-determined similarly to ruderal, segetal or some meadow phytocoenoses. The association Avenello flexuosae-Pinetum Matějka 1994 can be an example of such association. With the other types, only assigning to the unit of above-association level (alliance, order or class) can be expected. Thus the results are similar to those of deductive syntaxonomical classification used for the ruderal vegetation (see Kopecký, Hejný, 1978).

REFERENCES

ABRAHAMSEN, G., STUANES, A.O., TVEITE, B., eds., 1994. - Long-term experiments with acid rain in Norwegian forest ecosystems. Ecological Studies, New York, Vol. 104, 342pp.

BARKMAN, J.J., MORAVEC, J., RAUSCHERT, S., 1986. - Code of Phytosociological Nomenclature. 2nd edition. Vegetatio, 67: 145-195.

GRODZINSKI, W., WEINER, J., MAYCOCK, P.F., 1984. - Forest ecosystems in industrial regions. Studies on the cycling of energy nutrien and pollutants in the Niepolonice forest, Southern Poland. Ecological Studies, Vol. 49, Stuttgart etc., 277 pp.

HADAČ, E. et al., 1969. - Die Pflanzengesellschaften des Tales "Dolina Siedmich pramenov" in der Belaer Tatra. Vegetácia ČSSR, Bratislava, Ser. B., Vol. 2, 343 pp.

JAHN, G., ed., 1992. - Application of vegetation science to forestry. Handbook of Vegetation Science, Vol. 12, The Hague, 405 pp.

JAMSSON, P.-E., ed., 1990. - Air pollution, tree vitality, forest damage and production. The Skogaby Project. Project description. - University of Lunf, Uppsala, 80 pp.

KARRER, G., 1992. - Österreichische Waldboden-zustandsinventur. Teil VII: Vegetations-ökologische Analzsen. Mitteilungen der Forstlichen Bundesversuchsanstalt Wien, 168. Heft, Band II, p. 193-242.

KOPECKÝ, K., HEJNÝ, S., 1978. - Die Anwedung einer deduktiven Methode syntaxomischer Klassifikation bei der Bearbeitung der strassenbegleitenden Pflanzengesellschaften Nordostböhmens. Vegetatio, 36: 43-51.

LANDMANN, G., ed., 1993. - European network of permanent sample plots for monitoring of forest systems. In: Report on the follow-up, Ministerial conference on the protection of forests in Europe, 16-17 June 1993 in Helsinki, of the Strasbourg Resolutions. - Helsinki, p. 17-58.

LUISI, N., LERARIO, P., VANNINI, A., ed., 1993. - Recent advances in studies on oak decline. Proceedings of an International Congress Selva di Fasano (Brindisi), Italy, September 13-18, 1992. - Bari (Italy).

MAKIRINTA, U., 1990. - Validation of the Finish forest types by numerical methods illustrated by means of two sets of relevé data. Vegetatio, 88: 143-150.

MATĚJKA, K., 1993. - Diversity of ecological groups of species in cultural forests of South Bohemia. Ekológia (Bratislava), 12: 299-316.

MATĚJKA, K., 1994. - Phytocoenological and environmental conditions of the cultural forests in South Bohemia. In: K. Matějka, ed.: Investigation of the forest ecosystems and of forest damage. Lowland and submountain forests and monitoring of the forest status. - Praha, p. 8-28.

MEDWECKA-KORNAS, A., GAWRONSKI, S., 1990. - The dieback of fir Abies alba Mill. and changes in the Pino-Quercetum stands in the Ojcow National Park (Southern Poland). Vegetatio, 87: 175-186.

MORAVEC, J. et al., 1983. - Survey of the higher vegetation units of the Czech Socialist Republic. - Preslia, Praha, 55: 97-122.

PCC-West, PCC-East, 1994. - Manual on methods and criteria for harmonized sampling, assessment, monitoring and analysis of the effects of air pollution on forests. - Hamburg and Prague, 177 pp.

ROO-ZELINSKA, E., SOLON, J., 1990. - Phytosociological typology and phytoindicator value of young oak and larch forest communities near Pinczow (southern Poland). Vegetatio, 88: 67-78.

SCHULZE, E.-D., LANGE, O.L., OREN, R., eds., 1989. - Forest decline and air pollution. A study of spruce (Picea abies) on acid soils. Ecological Studies, Vol. 77, Berlin etc., 475 pp.

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Table 1. Defoliation of conifers in some countries during years 1986-94.

Fig. 1. Distribution of some chemical elements in the space of first two ordination axes of PCA on the basis of samples of spruce (Picea abies) first-year-class needles from 243 plots in the Czech republic (sampling year 1991). Similar distribution was obtained by the needles of 2nd-year-class.

Fig. 2. Distribution of some chemical elements in the space of first two ordination axes of PCA on the basis of samples of spruce (Picea abies) 3rd-year-class needles from 98 plots in the Czech republic (sampling year 1991). Similar distribution was obtained by the needles of 4th-year-class.

Fig. 3. Classification of the forest sampling plots in the Czech republic according results of foliar analysis (Picea abies needles of first-year-class) processed by principal component analysis (PCA; see Fig. 1). The classes in this map were distinguished using score on the 1st PCA axis. Borders of the selected regions were fitted using a combination of results first two PCA axes.

Fig. 4. Numerical classification (Ward's method with the Euclidean distance measure) of relevés presented by Hadač andSofron (1980). The presence/absence data of species in the herb layer was used. Relevé abbreviation consists of the original relevé number and an abbreviation of the association name (Sf-P Senecioni fuchsii-culti-Piceetum, Oa-P Oxalido acetosellae-Piceetum, Af-P Avenello flexuosae-Piceetum, Vm-P Vaccinio myrtilli-Piceetum, VmcP Vaccinio myrtilli-culti-Pinetum).

Fig. 5. Numerical classification (Ward's method with the Euclidean distance measure) of relevés presented by Hadač andSofron (1980). Original data of Domin-Hadač's abundance and dominance scale was used. Relevé abbreviations are the same as in Fig. 4.

Fig. 6. Numerical classification (Ward's method with the Euclidean distance measure) of relevés from three sets (Hadač, Sofron, 1980;Matějka, 1994; data obtained during course of monitoring under ICP-Forests) on the basis of the species covers in the herb layer. Several groups of communities were distinguished well: Qw some species rich oak forests, Qc oak forests with Calamagrostis arundinacea, g3+4 communities of classification groups 3 and 4 (Matějka, 1994), g5 communities of classification group 5 (Matějka, 1994), A-Q ass. Abieto-Quercetum (man-influenced forests), cover<5% coniferous stands with total cover of herb layer less then 5%, L-Q ass. Luzulo albidae-Quercetum (man-influenced forests), A-Pin1 ass. Avenello flexuosae-Pinetum, A-Pin2 ass. Avenello flexuosae-Pinetum (prevailing part of stands in South Bohemia).

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