WETLAND RESTORATION ENHANCES THE DEVELOPMENT OF PROTECTED SPECIES (IRIS SIBERICA L.) A CASE STUDY

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1 POLISH JOURNAL OF ECOLOGY (Pol. J. Ecol.) Research note Monika SPOREK, Agnieszka ROMBEL-BRYZEK University of Opole, Department of Ecology and Nature Conservation, Kominka 4, Opole, Poland, mebis@uni.opole.pl WETLAND RESTORATION ENHANCES THE DEVELOPMENT OF PROTECTED SPECIES (IRIS SIBERICA L.) A CASE STUDY ABSTRACT: The diminution of biological diversity is widely observed throughout the world in a variety of plant communities. Species protection itself is an insufficient form of preservation of the Siberian Iris population. A serious threat to this species is systematic diminishing of its typical habitat Molinietum caeruleae plant community, i.e. Molinia meadows on calcareous, peaty or clayey-silt-laden soils. Its maintenance is possible only through conservation and restoration of the plant communities in which it occurs. KEY WORDS: Iris siberica, population study, wetland In Poland the Siberian Iris (Iris siberica L.) is a plant under strict legal species protection, with a requirement for active conservation (Rozporządzenie ). In the Polish Red List of threatened plants it is labelled with signature V (Vulnerable) which means that the species is moderately declining (Z arzycki and Szeląg 1992). A serious threat to this species is diminishing of its typical habitat Molinietum caeruleae Koch 1926 plant community, i.e. Molinia meadows on calcareous, peaty or clayey-silt-laden soils (Matuszkiewicz 2001; Denisiuk 1995). The Siberian Iris grows also in swamp alder woods Ribo nigri Alnetum, alluvial Alno Padion forests, and is exceptionally found in mesotrophic parts of moist pine forests Molinio Pinetum (Matuszkiewicz 1982). Species protection itself is an insufficient form of preservation of the Siberian Iris population. Its maintenance is possible only through conservation of the plant communities in which it occurs. The Molinion alliance can be found in Annex I to the Habitat Directive (Council Directive 92/43/EEC of 21 May 1992 on the Conservation of Natural Habitats and of Wild Fauna and Flora; Council Directive 97/62/EC of 27 October 1997 adapting to technical and scientific progress ). In order to protect this plant associated areas in which it grows should be included in the net NATURA 2000 as Special Areas of Conservation (SACs). The European system of habitat classification attributed code 6410 to Molinia meadows on calcareous, peaty or clayey-silt-laden soils (Molinion caeruleae) (Devillers and Devillers-Terschuren 1996; Interpretation Manual of European Union Habitats 2003). Molinia meadows, where the Siberian Iris occurs, are connected with extensive agriculture. These meadows, not fertilised or journal 4.indb :27:45

2 592 Monika Sporek, Agnieszka Rombel-Bryzek sown, and mown once a year in late summer, are conspicuous for their unusual floristic value. The traditional form of management favoured the development of a characteristic composition of species, which resulted in a floristically rich and colourful plant community. At present Molinia meadows are a rather rare element of flora. Considering them as non-agricultural sites, the cessation of the traditional management, afforestation, and the drainage are the main factors leading to a reduction of their area and disappearance of the valuable plant species occurring Table 1. Individual characters in the population of Iris siberica L. under study. Character Value min max mean Standard deviation Variation coefficient [%] Height of flowering plants Length of inflorescence Number of flowers [number] Length of leaves journal 4.indb :27:45

3 Wetland restoration 593 here, not only the Siberian Iris. That is why the World Conservation Union (IUNC) includes humid and wet meadows among the most threatened habitats of Europe (D enisiuk 1995). Because of the elimination of flooding, intensive land drainage, and changes to arable grounds (B ekker 1989, Garcia 1992), such habitats became extremely rare. A considerable part of their characteristic flora became classified as central European species under protection (S chnittler and Günther 1999). In upper Rhine, as well as in the valleys of the Elbe and Danube in Germany, a large scale restoration of wet meadows with a variety of their plant species has been undertaken (Hölzer and Otte 2003). Our research were focused on the study of population dynamics and biometrical analysis of the Siberian Iris (Iris siberica L.). A meadow situated on foothills in the southern part of Poland (Kaczawskie Foothills, 51º27 N, 16º20 E) was selected as the study area. The whole complex of meadows extends to an area of 100 ha being crossed with numerous drainageditches. Niewiadoma (1997) mentions that before the drainage performed in 1992, the highest abundance of Siberian Iris in the region and one of the highest in Poland was noted in this area. Due to drainage of the habitat the Siberian Iris population survived only in the eastern part of the meadow, covering an area of about 20 ha. In 1997 Niewiadoma (1997) recorded 280 clumps. However in the year clumps of Siberian Iris were found in this area. This means that since 1997 the population increased almost four times. Moreover, the clumps were growing mostly along drainageditches. The most probable reason of such a considerable increase in numbers of the Siberian Iris was an improvement of moisture conditions. In 1994 the cessation of agricultural management of the meadows by a local state-owned agricultural farm took place, as well as the maintenance of drainage-ditches. It caused an increase in soil moisture which in turn resulted in the expansion of the Siberian Iris population. This is in accordance with the observations of Cabała and others (Cabała et al. 1996), who pointed at high requirements of Siberian Iris in relation to moisture conditions of habitat. For analyses of individual features five clumps were chosen at random. They comprised 133 blooming individuals and 566 without flowers. The share of young plants, not blooming (in vegetative phase) in the population was 81%, while in the case of blooming individuals (in generative phase) only 19%; so the proportion between phases was 4:1. The biometrical analysis comprised only blooming individuals. All the measurements were taken in a period of full blooming of the studied population, i.e. in the second half of June. The following individual features were measured to the nearest 1 cm: the height of plants (of the inflorescence shoots) and the length of inflorescences. All flowers in each inflorescence were counted. Additionally, the length of 10 leaves chosen at random from each previously selected clump was measured. Based on the biometrical measurements one can state that the individuals of studied population were in good condition. The measured values of plant height ranged from 25.5 to cm (Table 1). A large number of shoots exceeded 1m, and the number of flowers in an inflorescence was 4, on average. The mean length of inflorescences of the studied population was 17 cm. It seems that not only the density of clumps in the study area (~ 20 ha) increased since 1997 but the individual status of plants indicates favourable conditions for their growth. The soil samples were taken from the rhizosphere layer i.e. from a depth of cm in the close vicinity of clumps. The obtained values of ph ranged from 4.73 to The soil was qualified as slightly acidic to acidic (Gl i ńsk i 1999). Lub o- wicka (1984) states that the optimum range of ph for Siberian Iris is between 5 7. According to Cabała and others (Cabała et al. 1996) this species prefers slightly acidic soils, whereas Fijałkowski (1994, 1995) gives ph value 6.6. Hence, the obtained results are consistent with these data, however, it seems that slightly acidic soil is more favourable for the growth of Siberian Iris; it is indicated by the greater height of individuals in such places. journal 4.indb :27:45

4 594 Monika Sporek, Agnieszka Rombel-Bryzek Beside the Siberian Iris two other rare plant species were also found, that is the Broad-leaved Marsh Orchid (Dactylorhiza majalis (Druce.) Soo.), and the Common Gladiolus (Gladiolus imbricatus) both species are strictly protected by the Polish law (Rozporządzenie 2004). The conclusions from the research are: Due to land melioration of humid and wet meadows carried out in the 90 s, the population of Iris siberica L currently occupies only 1/5 of the previous habitat (~20ha). However the natural conditions for this type of habitat (Molinietalia), (light acidity, higher humidity) even on such a small area resulted in the increase of Iris siberica density and good condition of individuals. It seems that even insignificant wetland patches in the rural area with extensive agriculture, may be adequate to support refugees of many species as presented on the example of Iris siberica L. Molinietum caeruleae i.e. Molinia meadows on calcareous, peaty or clayeysilt-laden soils are hot spot of biodiversity in the landscape of Poland, and species Iris siberica L. can be used when selecting protected areas. REFERENCES Bakker J. P Nature management by grazing and cuttinag Werger, Kluwer Acad. Publ., Dordrecht-Boston-London. Cabała S., Bula R., Janas E Kosaciec syberyjski na wyżynie Śląskiej i terenach przyległych [Siberian iris in the Silesian Uppland and adjacent areas] Przyroda Górnego Śląska, 4:8, The Centre of the Heritage of the Upper Silesia, Katowice (in Polish). C ouncil Directive 92/43/EEC of 21 May 1992 on the Conservation of Natural Habitats and of Wild Fauna and Flora Official Journal L 206, P, C ounci l Dire c t ive 97/62/EC of 27 October 1997 adapting to technical and scientific progress Directive 92/43/EEC on the Conservation of Natural Habitats and of Wild Fauna and Flora Official Journal L 305, P, Denisiuk Z Godne ochrony łąki w Opatkowicach pod Krakowem [Meadows worth protection in Opatkowice near Cracow] Chrońmy Przyr. Ojcz., 51(4): (in Polish). Devillers P., Devillers-Terschuren J A classification of Palearctic habitats Nature and Environment, 78: Fijałkowski D. 1994, 1995 Flora roślin naczyniowych Lubelszczyzny [Flora of vascular plants of the Lublin region], vol. I, II, The Lublin Scientific Society, Lublin (after: Franszczak-Być M., Dąbrowska K Nowe stanowisko kosacca syberyjskiego Iris sibirica na Lubelszczyźnie [A new site of the Siberian iris Iris sibirica in the Lublin region]) Chrońmy Przyr. Ojcz., 56(5): (in Polish). Garcia A Conserving the species-rich meadows of Europe Agric. Ecosyst. Environ., 40: Glińsk i J Chemiczne i fizykochemiczne własciwości gleb [Chemical and physicochemical properties of soils] (In: Gleboznawstwo [Soil science] Ed. S. Zawadzki) PWRiL, Warszawa (in Polish). Hölzel N., Otte A Restoration of a species rich flood meadow by topsoil removal and diaspore transfer with plant material App. Veg. Sci., 6: Interpretation Manual of European Union Habitats EUR 25, version of April 2003 European Commission, DG Environment. Nature and biodiversity. Lubowicka H Kosaćce [Irises] PWRiL, Warszawa (in Polish) Matuszkiewicz W Przewodnik do oznaczania zbiorowisk roślinnych Polski [Guide to identification of plant communities of Poland] PWN Polish Scientific Publishers, Warszawa (in Polish). Matuszkiewicz W Przewodnik do oznaczania zbiorowisk roślinnych Polski [Guide to identification of plant communities of Poland] PWN Polish Scientific Publishers, Warszawa (in Polish). Niewiadoma J Opracowanie florystyczne Projektowanego Użytku Ekologicznego U 4 ; maszynopis [Flora of projected ecological land U4; typescript] (in Polish). Rozporządzenie Ministra Środowiska z dnia 9 lipca 2004 r. w sprawie gatunków dziko występujących roślin objętych ochroną [Regulation of the Minister of Environment of 9 July 2004 on the wild-growing plant species under protection.] Dz. U. Nr 168, poz (in Polish). Schnittler M., Günther K. F Central European vascular plants requiring priority conservation measures an analysis from journal 4.indb :27:45

5 Wetland restoration 595 national Red Lists and distribution maps Biodiv. Conserv. 8: Zarzycki K., Szeląg Z Czerwona lista roślin naczyniowych zagrożonych w Polsce [The Red List of the vascular plants endangered in Poland] (In: Lista roślin zagrożonych w Polsce [The list of plants endangered in Poland] Ed. K. Zarzycki, W. Wojewoda, Z. Heinrich) 2 nd Ed. W. Szafera Bot. Inst., PAN, Kraków (in Polish). (Received after revising July 2005) journal 4.indb :27:45