CHANGES IN VEGETATION COVER OF LOWER SILESIAN MONUMENTAL PARKS DUE TO DEGRADATION OF DRAINAGE SYSTEM AND CONCEPTS OF THEIR RESTORATION

Aleksandra Lis
Department of Landscape Architecture, Wrocław University of Environmental and Life Sciences, Poland

ABSTRACT

This paper describes the most often found effects of the drainage system degradation or alteration in the Lower Silesian palace and mansion parks set up in fertile habitats. Based on an example of the landscape setting in Królikowice, the research results on the issue are discussed and the proposed concepts of its restoration are presented. The discussion makes references to classical preservation models for restoration of garden art objects, identifying the needs for more research and studies and for the application of ecological principles to shaping vegetation settings which have undergone transformations as a result of changes in water conditions, as is the case with the Lower Silesian parks.

Key words: parks, restoration, drainage system, rural landscape .

INTRODUCTION

In the area of Lower Silesia, 19th-century landscape parks were usually set up on the basis of the existing tree stands growing in fertile habitats (fresh forests, humid forests, alder carrs, alder-ash carrs, riverside carr woodland [7]). In case of very humid, marshy and riverside habitats, water conditions were regulated by a drainage system installed before the introduction of new plantings, which was usually accompanied with stagnant water bodies (ponds, water channels). Due to the park maintenance discontinuation in the post-war period, ditches and water bodies often became overgrown bringing about the substantial rise in groundwater level in park areas. At the same time, the drainage systems of adjacent agricultural land as well as of timber forests were often converted without caring for draining the park, which was occasionally used as a water discharge area. As a result, there was a considerable increase in irrigation of the park setting as compared to the period of its foundation.

In the case of 19th-century Lower Silesian parks and major landscape settings, the most often found effects of the above-mentioned changes in water conditions and discontinuation of park maintenance include:

• extinction of skeletal tree stand (old-growth forest) specific for less wetted habitats constituting a basis of the original botanical composition of the park,

• secondary succession of vegetation in park blocks – emersion of hydrophilous plant communities of different species than those composing the park and, consequently, change in their physiognomy,

• in park clearings and meadows, due to the discontinuation of mowing occasionally combined with ground water logging – emersion of tall-herb and rushes communities at the initial stage and then willow and alder brushwood and shallow, often seasonal, water bodies,

• in the case of degradation of drainage system of forests – restoration of original (existing before the introduction of drainage system) habitat conditions and, as a result, change in species making up the tree stand and great diversity of vegetation pieces, especially in lower layers (undergrowth and herbaceous layer)

• overgrowing of stagnant water bodies (those constituting an element of the setting as well as secondary ones)

The scale of the above-mentioned effects in Lower Silesian parks differs – from local changes in park fragments (e.g., in Slęża, Rzeszówek) to extensive changes including the whole landscape setting consisting of the park and jointly composed landscape. The landscape setting in Królikowice is an example of the latter.

The purpose of the study was to determine the scope and character of changes in vegetation cover due to the degradation of drainage system within the landscape setting in Królikowice and to make an evaluation. The results of this study will be used to define concepts of the restoration of this landscape setting.

The present state of research includes: Inventory of the palace and landscape setting in Królikowice prepared in 1980 [2], updated inventories of the object presented in unpublished papers (mostly master’s theses lead by B. Stępniewska-Janowska at the Faculty of Architecture of the Wrocław University of Technology), and the studies on the object (including palace and farm buildings) described in Chapter 5 of the paper on 18th-century Silesian mansions [6]. An example design solution for the restoration of the complex was also presented in that paper. The research into the palace and park complex in Królikowice carried out by the author since 1994 was partly presented in the wider study on the palace and park complexes in the Lower Silesia [3]. The above-mentioned studies focused on the history of architectural and spatial changes in the object and did not include any analyses concerning natural transformations.

MATERIAL AND METHODS

The extensive (approx. 80 ha) landscape setting founded at the end of the 19th century in Królikowice has been selected for the study. The setting consisted of a palace park (6 ha) and circumjacent woodland, meadows and arable land with midfield and alley tree plantings, which were spatially associated with the park and the baroque palace, and enriched by additional elements (forester’s house, pheasantries). Due to the high humidity of the area, its agricultural use required the introduction of the drainage system which also covered the areas of woodland and mansion park.

The post-war inattention to the park and to the existing drainage system brought about the significant changes in water conditions. The overgrown drainage ditches failed to discharge rainwater to the nearby watercourse, which brought about the substantial rise in groundwater level and partial, seasonal flooding of areas located in land depression. Some time later, part of the drainage system was put in order but, at the same time, its arrangement was also modified to a significant extent. Large amounts of water were directed to a pond located in the central area of the depression rather than being discharged to the nearby watercourse the bottom of which is approx. 1.5 m below the level of that depression located in the west part of the setting. Thus, an interior basin was created, bringing about the substantial rise in groundwater level and seasonal flooding of meadows and part of woodland. Some meadow areas were permanently flooded.

The purpose of the study was to determine the scope and character of changes caused by inattention and alteration of water conditions within the landscape setting and to make an evaluation. Further historical investigations were not conducted because of the existing research studies. Field examinations of the landscape setting area were conducted in the years 1996–2004 in different seasons of the year. They were supplemented by comparative analyses completed with the use of archival and present plans of the setting.

STUDY RESULTS

As a result of the study, a comparative analysis has been completed, between the composition and spatial arrangements of the setting in the last phase of its development (before World War II) and in the present day, along with the description and evaluation of changes that occurred.

Both spatial arrangements, with designation of cartographic types of vegetation and, in the case of present state, with specification of major plant communities of tall vegetation, major composition elements and their relationships, are presented in Figures 1 and 2.

Description of changes in the natural arrangement of the setting and their effect on the compositional and natural values of the setting is presented in Table 1.

Changes with respect to architectural forms (removal of two farm buildings, removal of pheasantries and forester’s house, considerable devastation of other buildings) were not the subject of the study and analyses.

CONCLUSIONS – PROPOSED CONCEPTS OF RESTORATION OF THE SETTING

The results of this study may be used to define concepts of the restoration of the landscape setting in Królikowice. The author’s view on the issue in light of the coexistence of natural and cultural values is a new view formed during her own research into the complex.

The remarkably well-preserved spatial arrangement of the composed landscape is an undisputable value of the setting. Therefore, its obliteration must not be allowed. The possibility that the wet meadows will be overgrown by arborescent vegetation is a real threat for the spatial arrangement and this process has already begun. The simplest way to counteract this process would be the drainage of meadows and their systematic mowing. However, such measures would cause the decrease in groundwater levels in the whole setting. As a result, there would be a serious threat to the riverside carr woodland the compositional, economic and ecological values of which are now greater than in the last, pre-war phase of shaping the setting. The economic value of higher situated arable land would also decrease. Furthermore, the meadows, in their present ecologically diversified form, have not only a great natural value but even greater compositional value than before. In this situation, the reconstruction of the former drainage system would not be the proper solution. The only way of preserving the meadows in their present form (i.e., to preserve the tall-herb and rushes communities and, at the same time, to suppress the succession of arborescent vegetation) is to maintain them in the same manner as the so-called ecological lawns (late-autumn mowing with leaving the finely cut grass clippings). Any self-sown trees should be cut off in the summer time. Forests that are adjacent to the park should be maintained in order to preserve the present species. The evergreens is the only element of compositional value which disappeared from the pre-war look of the forests. It has adversely changed their visual qualities, especially in the leafless period. Therefore, it would be advisable to restore the evergreens. However, it should not be Norway spruce but hemlock due to better fitness to forest habitats, red cedar in riverside forests, and Douglas fir in dry-ground forests [1], [8]. The suitability of the latter was confirmed in the past by planting a double row of Douglas fir along the road leading from the railway stop to the former forester’s house.

In addition to the removal of self-sown trees, the park restoration should address the habitat conditions and ecological value of the existing plant communities. First of all, it is necessary to manage the existing vegetation cover, and new plantings must be fully adapted to the habitat conditions. This means that the park should be shaped with the use of ecological methods by taking advantage of its existing natural values. It would not be allowed to “clean up” the park by removing the undergrowth and middle layer of self-sown trees, which is the most often used method for overgrown parks. Except for areas overgrown with stinging nettle, the ground cover should be mowed at the end of vegetation season and not in the most intensive plant growth period, which is a common practice now.

DISCUSSION

Within the classical meaning, the restoration of monumental green areas means to restore the lost values to garden art objects [4]. Based on this definition, the commonly adopted process of research, studies and analyses has been established, to be carried out before the restoration project of monumental garden is prepared. The above-mentioned process is described in detail, among other publications, in Model postępowania konserwatorskiego dla zdewastowanych założeń ogrodowych przejmowanych przez Agencję Własnosci Rolnej Skarbu Państwa [5]. In this model, the garden restoration is meant as the activities aimed to preserve the cultural values of the object, including formal (aesthetic), material (historic) and functional values [5]. The proposed restoration concept for the setting in Królikowice, as well as for the similar Lower Silesian parks which have undergone transformations due to the change in their water conditions, departures from the classical garden restoration model. However, in this case, it is necessary to take into consideration the specific situation of the object. Its park part subject to conservatory protection is characterized, as compared to other palace and park complexes in the Lower Silesia, by a small aesthetic value [3]. The transformations within its vegetation cover due to the change in water conditions has brought about, in some parts of the complex, the considerable rise in the natural value of plant communities as well as in their aesthetic value. An attempt to restore the former habitat conditions would bring about the degradation of these communities. Hence the proposed concept of activities is aimed at their preservation with the simultaneous protection of the most important compositional values of the setting arising from the association of the park with the surrounding landscape.

The situation of the landscape setting in Królikowice in relation to the changes due to drainage system degradation is not an isolated case – it recurs in other Lower Silesian parks. In order to perform proper evaluation and to establish guidelines for the restoration project, in these cases, it is necessary to expand the classical conservatory procedure by:

• studies aimed to identify the character of changes in habitat conditions and vegetation cover and to determine their causes,

• evaluation of the natural value of new (transformed) plant communities,

• comparative analysis of the aesthetic values of the park between the most valuable phase of its development and the present state giving consideration to the aesthetics of new plant communities,

• evaluation of the anticipated effects of former water condition restoration with respect to the existing vegetation.

Where the lost historical value of the whole or part of the park is insignificant, it may be advisable to consider an alteration of the method of protection with the preservation of plant communities the natural and aesthetic values of which give the object the new value.

The above proposed methods of restoration are based on the principles of ecological shaping of green settings. They may be referred to as the ecological concept of restoration. In the case of the setting in Królikowice, which is an enclave of disappearing communities of hydrophilous plants and their resultant ecosystems in the European scale, it is fully justified to treat the whole complex as an ecological land. This does not preclude the economic use of forests and arable land for which the agricultural chemicalization should be restricted and selective measures applied if necessary. However, it is also necessary to preserve the cultural values of the composed landscape, which will lead to the transformation of the setting into composed ecological land.

REFERENCES

1. Hrynkiewicz-Sudnik J., Sękowski B., Wilczkiewicz M., 1999. Rozmnażanie drzew i krzewów nagozalażkowych [Reproduction of gymnospermous trees and shrubs]. Warszawa, PWN [in Polish].

2. Idzikowska H., 1980. Ewidencja założenia pałacowo-parkowego w Królikowicach [Inventory of the palace and landscape setting in Królikowice]. BIPROZET, Wrocław [in Polish].

3. Lis A., 1997. Metoda waloryzacji założeń pałacowo-parkowych na przykładzie Dolnego Slaska [Method of palace and landscape setting evaluation on the example of Lower Silesia]. Ph.D.dissertation. Wrocław, Wydz. Arch. PWr [in Polish].

4. Majdecki L., 1993. Ochrona i konserwacja zabytkowych założeń ogrodowych [Protection and conservation of historic garden settings]. Warszawa, PWN [in Polish]

5. Mitkowska A., Fabijanowska K., Uruska-Suszek D, Zachariasz K., Tor K., 1994. Model postępowania konserwatorskiego dla zdewastowanych założeń ogrodowych przejmowanych przez Agencję Własnosci Rolnej Skarbu Państwa. [Model of conservation procedure for devastated garden settings taken over by the Agricultural Property Agency of the Treasury]. Studia i Materiały, seria: Ogrody 2(8) [in Polish].

6. Stępniewska B., 1993. Rezydencje na Slasku w XVIII wieku [Mansions in XVIII century Silesia]. Wrocław, Wyd. Pwr [in Polish].

7. Szymański S, 2000. Ekologiczne podstawy hodowli lasów [Ecological basis of silviculture]. Warszawa, Państwowe Wydawnictwo Rolnicze i Lesne [in Polish].

8. Tomanek J., 1994. Botanika lesna [Forest botany]. Warszawa, PWRiL [in Polish].

Accepted for print: 28.04.2007

Responses to this article, comments are invited and should be submitted within three months of the publication of the article. If accepted for publication, they will be published in the chapter headed 'Discussions' and hyperlinked to the article.