Is the riparian habitat creation an effective measure of plant conservation within the urbanized area?

Ecological Engineering 83 (2015) 125–134

Contents lists available at ScienceDirect

Ecological Engineering journal homepage: www.elsevier.com/locate/ecoleng

Is the riparian habitat creation an effective measure of plant conservation within the urbanized area? Arkadiusz Nowaka,b,d,* , Magdalena Ma
slakb , Marcin Nobisc , Sylwia Nowaka , Paweł Kojsb , Agata Smiejab a

Department of Biosystematics, Laboratory of Geobotany & Plant Conservation, Opole University, 45-052 Opole, Poland Silesian Botanical Garden, Mikołów, Poland Department of Plant Taxonomy, Phytogeography and Herbarium, Institute of Botany, Jagiellonian University, Kopernika St. 27, 31-501 Kraków, Poland d Department of Biology and Ecology, University of Ostrava, 710 00 Ostrava, Czech Republic b c

A R T I C L E I N F O

A B S T R A C T

Article history: Received 16 October 2014 Received in revised form 12 May 2015 Accepted 8 June 2015 Available online xxx

The study presents results of habitat creation and riparian vegetation recovery in artificial oxbow lakes in urbanized area within the large river valley. The investigation of open water, rush and wet meadows flora and vegetation in three ponds located in the city centre of Opole was conducted in years 2001–2013. Oxbow lakes were constructed as a compensation measure and no vegetation was transplanted into the ponds on purpose. 13-years observation showed that (1) the red-listed species are able to spontaneous reoccurrence after habitat restoration, but they can thrive only in first years of oxbow lakes recolonisation process, (2) there are some restoration constraints, especially in relation to Phragmites australis and Nuphar lutea expansion, but alien species invasions were insignificant and (3) the species number and vegetation cover was constantly increasing during the recolonisation process in recreated oxbow lakes. The dynamic of vegetation was considerable, especially in first 6 years of experiment when the significant increase in diversity and richness of native plant species was observed. After that time, the increasing expansion of P. australis and N. lutea was noted causing the decline of several species and vegetation types. So, restoring just the environmental conditions may be sufficient for a limited period of time only. Strong disturbances, much intense that moderate inundations, imitating disastrous flooding within the valley each 10–13 years are need to maintain the ecological niches for river corridor and riparian species. ã 2015 Elsevier B.V. All rights reserved.

Keywords: Constructed habitat Ecological restoration Odra river Plant diversity Poland Rush communities

1. Introduction Due to the richness of distinct plant and animal species, diversity of plant communities as well as significant decline of the number or quality of the oxbow lakes of large rivers in last centuries, these biotopes are valuable conservation areas in lowland Europe (Ot’ahel’ová et al., 2007; Erwin, 2009). This floodplain ecosystems are also recognized as one of the most susceptible to the climate change and are going to lose their functional capacity (Erwin, 2009). The needs of inland transport and the anti-flooding investments (ditches, dikes, embankments) cause considerable shrinkage of this type of habitats and as a consequence the withdrawal of many wetland species (Tockner and Stanford, 2002). As an example, in the southern Poland three main rivers, namely the Oder, Vistula and San were shortened by the river engineering works in the 19th century by about 20–30% (Tomiałoj
c, 1993; Jermaczek et al., 1996; Rast et al., 2000). Like in

* Corresponding author. E-mail address: [email protected] (A. Nowak). http://dx.doi.org/10.1016/j.ecoleng.2015.06.009 0925-8574/ ã 2015 Elsevier B.V. All rights reserved.

many other countries in Europe, the side lakes of the Oder River are subjected to strong impacts and influences. Among the most significant are enrichment of nutrients and eutrophication of water, often causing hypereutrophication. The stream channelization and flow regulation have also altered significantly the water regime of rivers. Along with this man-made changes of river floodplains, it is also worth considering that the surrounding of oxbow lakes has changed through centuries from forested areas, followed by grasslands to intensively used arable fields nowadays. The strong impact of agriculture combined with anti-flooding constructions make the oxbow lakes the last refuge for many wetland species (Gallardo et al., 2012; Knight et al., 2013). The habitat is protected by the EC Habitat Directive 92/43/EEC. Many endangered or rare species and plant communities have been found here. For example in Poland, the most valuable plants are Corrigiola litoralis,Carex buekii, Cnidium dubium, Thalictrum flavum, Mentha pulegium, Leonurus marrubiastrum, Euphorbia palustris, E. lucida, Wolffia arrhiza. There are also many other typical river valley plants of more frequent distribution like Alisma lanceolatum, Allium angulosum, Butomus umbellatus, Eryngium planum, Melampyrum

126

A. Nowak et al. / Ecological Engineering 83 (2015) 125–134

cristatum, Scrophularia scopoli, Stratiotes aloides, Symphytum tuberosum and others (Burkart, 2001; Nobis and Skórka, 2014). Also several important vegetation types still occur within the valley on the Opole Silesia section. After the disastrous flood in southern Poland in 1997, the central and regional authorities implemented a modernisation programme of hydrotechnical systems alongside the Oder River (Oder 2006 programme). The rebuilding of “hydrotechnical node Opole” was a part of this project which main goal was to increase the water capacity of the river valley during the inundations. As it was enumerated in the project, the regional authorities build new water embankments and a new bypass channel. As a result two oxbow lakes have to be eliminated. During the environmental impact assessment procedure the creation of three artificial oxbows has been imposed on investor as a compensation measure. The main goal of this study is to assess the vegetation changes and population dynamics of target species in these artificial oxbows. After habitat recreation, we started observations of the secondary succession to determine the directions of vegetation changes and predict the longevity of that kind of artificial reservoirs. At the beginning of our study it was hypothesised that the secondary succession would start shortly after recreation of oxbow lakes. The fast colonisation by different therophytes and anthropophytes as well as expansive native species and alien invasive species would happen on the lake banks. We expected also that spreading of expansive native plants like P. australis and increasing participation of alien invasive plants (common in the Oder valley) would occur after about 5 years further. However, we were not sure what the succession rate and the dynamics of distinct species populations would be. To assess the vegetation changes and population dynamics of target species in restored three artificial oxbow lakes, we are going to answer the following questions: (a) what is the diversity, composition and dynamics of vegetation in created oxbow lakes? (b) what are the restoration constraints, especially in relation to the P. australis expansion and alien species invasion in urbanised areas? and (c) are the red-listed species capable of spontaneous reoccurring after the habitat creation? 2. Methods 2.1. Study area The Oder river is crossing the Opolskie Province in a valley of different width, approximately 1 km in Morawa Gate and about 12 km in the central part of the regional section (Badora, 2001). The valley area had been intensively changed by humans already in Middle Ages. The river was used for transport, sailing and rafting. During those times many woodlands were changed into agricultural plots and the river was partially regulated (Rast et al., 2000). Today, the Oder valley landscape is a mosaic of forest patches, meadows, pastures, rushes, mud vegetation, arable lands, as well as dry grasslands developed on slopes of the valley margins and anti-flooding embankments. Because of the frequent floods in the city area in the second half of the 19th century in western part of the city the by-pass channel “Ulga” was built within the Odra River valley. The channel is about 6 km long, 200 m wide and is embanked on both sides. The three artificial oxbow lakes were dug between the Ulga channel embankments within the Oder River valley in central part of Opole in 2000 (Fig. 1). They have a rectangular shape, depth of 1.8 m and different surface area: 740 m2, 890 m2 and 2070 m2 (reservoirs 1, 2 and 3, respectively (Fig. 1)). The artificial oxbows were dig in the wings of the Oder valley in close vicinity of the Ulga Channel (about 30 m). Before the habitat creation works, the area was covered by the anthropogenic grassland with the dominance

Fig. 1. The location of research area in Poland.

of species typical to fresh meadow Arrhenatherion elatioris. The main contributors were Centaurea jacea, Poa trivialis, P. pratensis, Galium mollugo, Lathyrus pratensis, Leontodon autumnalis and Arrhenatherum elatius. Only a very narrow margin of the Ulga Channel stream was sparsely overgrown by rush vegetation with Bolboschoenus maritimus, P. australis and Scirpus lacustris. The aim of the lake digging was to create a substitute habitat for two natural oxbows of the Oder River undergoing destruction due to anti-flooding works within floodplain, about 4 km upstream. No plant translocation measures were taken after digging so the vegetation was spontaneously re-established with no conservation support. The area is regularly inundated by flooding waters. During the research, the inundations were observed each year between May and July, however with no destruction of vegetation cover occurred. The last catastrophic inundation took place in 1997. 2.2. Sampling Monitoring of spontaneous plant colonisation in the restoration site started in 2001 (i.e. the second growing season after habitat creation). Plant species composition and cover were sampled in fourteen 2 m  2 m plots distributed along 3 transects in each artificial oxbow lake (Fig. 2). The examined plots cover all types of wetland habitats, i.e. open water, rushes, edge vegetation (meadow or tall-herbs) and mud vegetation. Altogether 42 plots were sampled in 2001, 2002, 2003, 2005, 2007, 2009, 2011 and 2013. The

Fig. 2. Sampling design of the research in a one oxbow lake. Explanations: Waquatic (water) plot, R-riparian plot, M-meadow plot.

A. Nowak et al. / Ecological Engineering 83 (2015) 125–134

vegetation data were collected from 20 June to 30 July during the full vegetation season. The percentage scale was applied to estimate the cover of all vascular plants within plots. When a plant covered less than 1%, this was recorded as 0.5%. The nomenclature of the species follows Mirek et al. (2002). Taxa were classified into a vegetation units according to Matuszkiewicz (2001). They were classified into 6 major ecological groups: (1) aquatic plants (representatives of Potametea and Lemnetea, POLE), (2) late summer therophytes (Bidentetea tripartiti, BT), (3) rush plants (Phragmitetea, Phr), (4) water margin plants (Convolvuletalia sepium, Cs), (5) meadow plants (Molinio-Arrhenatheretea, MA) and (6) nitrophilous wet swards (Agropyro-Rumicion crispi, AR). When classifying plants into geographical or

127

conservation groups, the works of Tokarska-Guzik, 2005; Zaja˛c and Zaja˛c, 2009; Zaja˛c et al., 2009 (archaeophytes, kenophytes), Nowak et al., 2008 (red-listed species), Burkart, 2001; Nobis and Skórka 2014 (river corridor species) were applied. Ruderal species were defined as those occurring typically in vegetation plots of Stellarietea mediae, Artemisietalia vulgaris and Onopordetalia acanthii habitats (Matuszkiewicz, 2001). 2.3. Statistical analyses The relationships between the sample groups were examined using ordination techniques. The species data showed a clear unimodal response, enabling us to use the canonical

Fig. 3. Changes in the percentage cover of vegetation, archaeophytes, kenophytes, ruderal species, red-listed species, river corridor species, water species, nitrophilous wet sward species, late summer terophytes, water margin tall-herb species, meadow species and rush species. Abbreviation: see sampling section in methods.

128

A. Nowak et al. / Ecological Engineering 83 (2015) 125–134

correspondence analysis (CCA). To check relationships and tendencies in species composition in the following years and to show the relationships between the groups of indicator species the CCA was applied with the floristic abundance, log-transformed data, with downweighting of rare species. We used a detrended option to remove the arch effect and improve the fit to the Gaussian model. In order to clearly depict the results of analysis, we performed it separately for water, rush and meadow vegetation plots as well as for all samples. The significance of the environmental variables was calculated using a Monte Carlo test (499 permutations) and only predictors with a significance of p < 0.05 were included in the CCA model. Canoco for Windows 4.5 was used for the ordination, (ter Braak and Šmilauer, 2002; Lepš and Šmilauer, 2003).

To find the succession pattern of species and group of species in plots in a given year, we compared the mean values of summarised cover of species from a given habitat type (outside meadow, rushedge zone and open water) using the non-parametric Kruskal– Wallis one-way analysis of variance. The same statistical tool was used to find relations between cover values and richness of species from different ecological groups as well as groups with different significance for conservation (Phragmitetea, Convolvuletalia sepium, Lemnetea-Potametea, Agropyro-Rumicion crispi, Molinio-Arrhenatheretea, Bidentetea, B. tripartiti, woody species, ruderal species, archaeophytes, red-listed species and kenophytes). The Statistica software was used to perform these analyses (StatSoft Inc., 2010).

Fig. 4. Changes in total number of species, archaeophytes, kenophytes, ruderal species, red-listed species, river corridor species, water species, nitrophilous wet sward species, late summer terophytes, water margin tall-herb species, meadow species and rush species. Abbreviation: R-number of species, others—see Section 2.2.

A. Nowak et al. / Ecological Engineering 83 (2015) 125–134

129

3. Results 3.1. General vegetation cover, richness and diversity in various patches during the study period The total number of taxa recorded in all plots was 155, with 28 of which exceed 10% of frequency and 62 exceed 5%. The group with the highest record frequencies includes the following species: P. australis (135 records), P. trivialis (108), Festuca rubra (104), Carex hirta (96), Potentilla reptans (95), Trifolium hybridum (83), Vicia cracca (81), Plantago lanceolata (74), Phalaris arundinacea (68), Ranunculus repens (67) and Trifolium repens (66). The most frequent archaeophytes were Echinochloa crus-galli (29), Capsella bursapastoris (20) and Chenopodium ficifolium (19). The most common kenophytes in the research plots were Conyza canadensis (48) and Solidago canadensis (11). Among red-listed species Potamogeton pusillus (6) and Salvinia natans (6) have the highest frequencies. Both, the vegetation cover and richness of species in various plots increased very fast after the reservoirs were dug. Already after three years, the mean cover reached about 50% and the richness 9 taxa per plot. With steady, albeit slower growth in the following period, after 13 years the values reached about 85% and 16 species per plot, respectively (Figs. 3, 4). 3.2. Dynamics of individual vegetation types Analysing the development and speed of expansion of various plant types, attention should be paid to the fact of very early and abundant appearance of water species, late summer therophytes and nitrophilous wet swards (Figs. 5–8). The population size of such species as Bidens frondosa, C. ficifolium, Agrostis stolonifera (in the rush zone), C. hirta, Trifolium sp., C. canadensis (in the meadow zone) or P. pusillus (in water) rose very quickly and already after 2 years they covered a significant area of research plots. The delay was noted in the expansion of wet and water margins plants (Convolvuletalia sepium) which started to appear in the tested

Fig. 5. CCA ordination triplot for oxbow vegetation in 2001–2013 (p < 0.005, F = 11.62). Species name abbreviations: Agr.sto.-Agrostis stolonifera, Bid.fro.-Bidens frondosa, Bol.mar.-Bolboschoenus maritimus, Cal.sep.-Calystegia sepium, Car.hir.-Carex hirta, Che.fic.-Chenopodium ficifolium, Con.can.-Conyza canadensis, Cyp.fus.-Cyperus fuscus, Fes.rub.-Festuca rubra, Hie.odo.-Hierochloe odorata, Lem.min.-Lemna minor, Nup.lut.-Nuphar lutea, Pha.aru.-Phalaris arundinacea, Phr.aus.-Phragmites australis, Poa tri.-Poa trivialis, Pot.pus.-Potamogeton pusillus, Pot.luc-P. lucens, Pot.rep.Potentilla reptans, Sal.pur.-Salix purpurea, Sal.nat.-Salvinia natans, Spi.pol.-Spirodela polyrhiza, Tri.hyb.-Trifolium hybridum, Tri.rep.-Trifolium repens.

Fig. 6. DCCA ordination triplot for oxbow meadow vegetation in 2001–2013 (p < 0.005, F = 14.71). Species name abbreviations: Ach.mil.-Achillea millefolium, Alo. pra.-Alopecurus pratensis, Arr.ela.-Arrhenatherum elatius, Car.hir.-Carex hirta, Dac. glo.-Dactylis glomerata, Fes.rub.-Festuca rubra, Gal.mol.-Galium mollugo, Lat.pra.Lathyrus pratensis, Leu.vul.-Leucanthemum vulgare, Pla.lan.-Plantago lanceolata, Pot. rep.-Potentilla reptans Poa tri.-Poa trivialis, Tri.hyb.-Trifolium hybridum, Tri.pra.Trifolium pretense.

patches approximately 3 years after creation of habitats. A similar delay was observed in case of typically meadow and rush species (e.g. L. pratensis, P. reptans, P. trivialis, P. arundinacea), but in these groups the maximum levels were not reached even after 13 years, and the values are consistently growing. Particularly the rush vegetation reaches very high average share in the cover, although it shows a constant floristic impoverishment in terms of species richness (Figs. 3, 4). Over the course of time, the dominance of P. australis is increasingly visible and this species is responsible for an increased share in plots despite the decreasing overall number of Phragmitetea species (Figs. 3, 4).

Fig. 7. DCCA ordination triplot for oxbow water vegetation in 2001–2013 (p < 0.005, F = 8.64). Species name abbreviations: Cha.sp.-Chara sp., Ce.dem.-Ceratophyllum demersum, Lem.min.-Lemna minor, Lem.tri.-Lemna trisulca, Nup.lut.-Nuphar lutea, Pot. luc.-Potamogeton lucens, Pot.nat.-P. natans, Pot.pec.-P. pectinatus, Pot.pus.-P. pusillus, Sal.nat.-Salvinia natans, Spi.pol.-Spirodela polyrhiza.

130

A. Nowak et al. / Ecological Engineering 83 (2015) 125–134

4. Discussion 4.1. Dynamics of the vegetation

Fig. 8. DCCA ordination triplot for oxbow riparian vegetation in 2001–2013 (p < 0.005, F = 9.78). Species name abbreviations: Agr.sto.-Agrostis stolonifera, Bid. fro.-Bidens frondosa, Bol.mar.-Bolboschoenus maritimus, Cal.sep.-Calystegia sepium, Che.fic.-Chenopodium ficifolium, Che.rub.-Chenopodium rubrum, Car.ela.-Carex elata, Car.pse.-Carex pseudocyperus, Ele.pal.-Eleocharis palustris, Eup.can.-Eupatorium cannabinum, Fal.dum.-Fallopia dumetorum, Gly.max.-Glyceria maxima, Pha.aru.Phalaris arundinacea, Phr.aus.-Phragmites australis, Ror.amp.-Rorippa amphibia, Sch. lac.-Schoenoplectus lacustris, Typ.lat.-Typha latifolia.

3.3. Share of species from individual synanthropodynamic groups Initially, the floristic structure of the monitored plots along with the native plants often included alien species, including kenophytes (S. canadensis, Erigeron annuus, Echinocystis lobata, C. canadensis, B. frondosa and Aster lanceolatus) and archaeophytes such as C. bursa-pastoris, C. ficifolium, E. crus-galli, Erysimum cheiranthoides, Matricaria maritima subsp. inodora, Veronica peregrina, Vicia villosa and Viola arvensis). However, after 4–5 years their share, both in terms of number of species and the abundancy in the vegetation plots, decreased considerably almost to negligible values (Figs. 3–5, Table 1). The dynamics of red-listed species is a bit different. No target species were found in the monitored plots in the first year of observation. Then, their share consistently grew, and started to reduce gradually after about 7 years. The share and number of redlisted species is not considerably high. It is worth noting however that all species which triggered the restoration project, i.e. B. maritimus and B. umbellatus inhabited the new ecosystem. Additionally, the newly created habitat was inhabited by S. natans, Spirodela polyrhiza, P. pusillus, P. lucens, Cyperus fuscus, and even by Hierochloe odorata which is considered extinct in the region (Fig. 9). 3.4. Share of corridor species Both in terms of number of species found and their share in the patches, the river corridor indicators were not a significant element of vegetation within the monitored reservoirs (Fig. 8). Only the share and frequency of C. ficifolium in vegetation plots had considerable values, especially in the first 3 years. Also, the abundancy of S. natans increased in 2007 and 2008 in the smallest reservoir. Other species, like Rorippa austriaca, B. maritimus and Potentilla supina had insignificant covers.

It was not surprising that the spontaneous reestablishment of vegetation on the completely bare ground after digging the artificial oxbow lakes was so fast. In many researches it was reported that after just few years past the intervention the plant association could cover considerable surface (Prach and Pyšek, 2001; Norman et al., 2006; Poulin et al., 2012). We can observe sequences of the succession within this artificially created habitats as we know it from the natural reservoirs after disturbance. In the terrestrial habitats the first stage of succession is driven mainly by species typical for late summer vegetation of wet biotopes like river banks (Chytrý, 2011). They belong generally to Bidentetea tripartiti class represented mainly by Alopecurus aequalis, B. frondosa, Chenopodium rubrum, Ch. ficifolium, Polygonum hydropiper and Ranunculus sceleratus. Also plants from nitrophilous wet swards and meadows are quite common in first period of succession. In our case the most frequent species from this type of vegetation (Agropyro-Rumicion crispi) were A. stolonifera, P. reptans, Lysimachia nummularia, Potentilla anserina and R. austriaca. With increasing biomass accumulation, the rush and meadow species have come on the stage. The plots on margins of the reservoirs are overgrown by rush species in course of next few years. At the beginning the plots of rush vegetation are composed of several species which build a mosaic of different plant communities with domination of S. lacustris, Glyceria maxima, Typha latifolia, B. maritimus. After 6–7 years rushes tend to be unified along with the decrease of species richness. The P. australis stands dominate and as a strong competitors wipe out other rush communities. This is in line with research results in several other regions (Philipp and Field, 2005; Liu et al., 2012; Howard and Turluck, 2013). The abundance of Phragmites in research plots was probably related to the increased availability nitrogen and phosphates of in soil (Brülisauer and Klötzli, 1998). The accumulation of biomass during 13 years and eutrophic sediments of Odra River as result of yearly inundations support stands of P. australis which clearly benefits from these processes. The dense and widespread stands of P. australis could cause a loss of red-listed species which show significant decrease in abundance and richness after 7–9 years. Especially rush taxa like B. maritimus or B. umbellatus cannot withstand the competition with P. australis and disappear. Certain saturation in terms of floristic richness was noticed in the final years of observation. There was even a decrease in number of some species (Figs. 3, 4). The species richness indicators for therophyte, red-listed species, archaeophytes and almost all ecological groups (except for Molinio-Arrhenatheretea taxa) initially grow and then start to decrease, the reason being that the speed of species exchange is greater at the early stages of regeneration and the species durability is shorter. Hence, the presence of many species typical for different syntaxa. The habitats more advanced in regeneration of vegetation are more durable in terms of types of phytocoenoses present and at the same time they are poorer in terms of species diversity. The phenomenon of increasing species diversity along with the progress of regenerative succession, followed by saturation has been observed earlier (e.g. May and MacArthur, 1972; Huston, 1979). 4.2. No considerable encroachment of alien species In restoration sites in a first stage of succession, many invading species could considerably hamper the regeneration process and effectiveness of this conservation measure (Berling, 1995; Pyšek et al., 1995; Starfinger et al., 1998). It was a bit astonishing that after

A. Nowak et al. / Ecological Engineering 83 (2015) 125–134

131

Table 1 Averages of vegetation cover (SE), species richness, plot diversity and cover of geographical and ecological groups of species. Significant differences between values were tested with a Kruskal–Wallis test. Significant differences were shown in bold (p < 0.05). Abbreviation: H-plot species Shannon–Wiener diversity. Water plots

2001 2002 2003 2005 2007 2009 2011 2013

Species number

Species cover

H

Archeophytes cover

Kenophytes cover

Red-listed species cover

Corridor species cover

00 1.33  0.52 2.67  1.21 3.83  1.83 4.33  1.03 4.33  1.03 4.5  0.84 4.33  1.21

00 38.32  16.04 36.83  22.92 43.52  14.02 56.53  12.67 60.13  27.24 64.87  20.27 80.53  9.32

00 0.06  0.09 0.59  0.57 0.78  0.59 0.93  0.39 0.89  0.53 0.7  0.32 0.63  0.36

00 00 00 00 00 00 00 00

00 00 00 00 00 00 00 00

00 0.33  0.52 0.5  0.55 0.83  0.98 1  0.63 0.83  0.75 1  0.89 0.67  1.03

00 00 00 00 8.5  15.36 12.67  25.2 1  1.55 00

Species number

Species cover

H

Archeophytes cover

Kenophytes cover

Red-listed species cover

Corridor species cover

3.61  1.54 7.83  1.79 8.56  1.65 7.33  1.88 7.44  1.65 5.83  1.58 4.83  1.04 4.22  0.73

7.26  2.91 19.28  5.06 48.87  16.19 57.17  14.47 70.52  16.57 76.22  18.33 82.02  16.12 85.54  8.74

1.17  0.5 1.93  0.28 1.35  0.43 1.22  0.47 0.99  0.3 0.73  0.32 0.61  0.33 0.5  0.19

2.04  1.8 5.96  4.43 1.22  1.68 00 00 00 00 00

2.06  1.39 2.92  3.42 2.05  1.34 0.11  0.47 00 00 00 00

00 00 0.06  0.24 0.06  0.24 00 00 00 00

00 2.05  1.54 1.17  3.13 0.22  0.65 00 00 00 00

Species number

Species cover

H

Archeophytes cover

Kenophytes cover

Red-listed species cover

Corridor species cover

3.28  1.41 6.56  1.38 12.61  2.66 12.06  2.58 15.83  2.92 20.72  3.12 23.5  2.15 25.06  2.48

6.69  2.93 17.43  5.27 50.49  10.65 53.23  11.73 61.92  10.48 71.64  9.89 82.08  5.33 87.71  2.81

1.07  0.52 1.76  0.21 2.08  0.3 1.97  0.31 2.21  0.27 2.46  0.21 2.56  0.15 2.68  0.13

1.6  1.73 0.94  1.26 0.33  0.77 0.11  0.47 00 0.11  0.47 0.5  1.2 0.33  0.77

1.94  1.46 2.22  1.17 1.33  1.19 0.61  1.04 0.22  0.65 0.17  0.71 0.11  0.47 00

00 00 00 0.06  0.24 0.17  0.38 0.17  0.38 0.11  0.32 0.06  0.24

00 0.39  0.92 0.11  0.47 00 00 00 00 00

Species number

Species cover

H

Archeophytes cover

Kenophytes cover

Red-listed species cover

Corridor species cover

2.95  1.82 6.36  2.61 9.45  3.96 8.86  3.72 10.6  5.19 12  7.99 12.79  9.52 13.17  10.56

5.98  3.64 21.2  10.21 47.85  15.53 53.53  13.72 64.84  14.38 71.96  17.29 79.6  14.38 85.75  7.16

0.96  0.61 1.59  0.68 1.56  0.66 1.48  0.62 1.5  0.68 1.5  0.91 1.46  1 1.45  1.09

1.56  1.74 2.96  3.98 0.66  1.29 0.05  0.31 00 0.05  0.31 0.21  0.81 0.14  0.52

1.71  1.48 2.2  2.52 1.45  1.34 0.31  0.78 0.1  0.43 0.07  0.46 0.05  0.31 00

00 0.05  0.22 0.1  0.3 0.17  0.49 0.21  0.47 0.19  0.45 0.19  0.51 0.12  0.45

00 1.05  1.46 0.55  2.11 0.1  0.43 1.21   6.15 1.81  9.88 0.14  0.65 00

Riparian plots

2001 2002 2003 2005 2007 2009 2011 2013

Meadow plots

2001 2002 2003 2005 2007 2009 2011 2013

All plots pooled together

2001 2002 2003 2005 2007 2009 2011 2013

relatively short period of time, the alien species were scarce and occur in small population sizes. It was rather unexpected having in mind that Oder valley is commonly inhabited by several kenophytes like Acer negundo, E. lobata, Impatiens glandulifera, A. lanceolatus, Solidago serotina, Lycopersicon esculentum, Typha laxmannii and others (e.g. Dajdok et al., 1998; Dajdok and Ka˛cki, 2003; Nobis et al., 2006). The only exception is B. frondosa with relatively high frequency and abundance in researched plots. There are some native ruderal species achieving considerable cover values, however only in first two years (2 taxa on average and approximately 5% average cover). But even this group of species is outcompeted by native species typical for riparian habitats and declines after two years to negligible values about 1% of average cover value and approximately 0.5 species per plot. This is despite the fact that the artificial oxbows were dug in the city centre where the anthropogenic pressure by anglers, recreational activities, unregulated waste dumping is still present. The alien and ruderal species pool could also potentially influence the study area within the Odra river valley urbanised section. The insignificant encroachment of alien species to open habitats of bare and sandy lands in

the river valley rather contradicts the commonly accepted view that such kind of biotopes are seriously threatened by alien and invasive plants (e.g. Tokarska-Guzik, 2003; Kühn et al., 2003; Tokarska-Guzik, 2005; Chytrý et al., 2008; Botham et al., 2009). This could be probably explained that the spontaneous succession and regeneration after vegetation destruction (during the hydrotechnical works) is to a large extent driven by the natural processes of recolonization with great support of surrounding diaspore pool from the Oder River corridor. Also moderate cyclic flooding helps re-establish the vegetation cover which is composed in majority by native and typical for riparian habitats species. The number and abundance of alien or invasive species depends here mainly on the surrounding diaspore pool and types, strength and frequency of human intervention, which in our case were not so destructive. Similar results were obtained in researches of succession and restoration of anthropogenic habitats in the Czech Republic (Prach et al., 1999, 2001; Novák and Prach, 2003). The strong competitiveness potential of native species, mainly rush plants, creates unsuitable existence conditions for the alien species.

132

A. Nowak et al. / Ecological Engineering 83 (2015) 125–134

Fig. 9. The average cover values of red-listed species in sample plots during the research period.

4.3. Expansion of P. australis P. australis is a cosmopolitan, world-wide distributed species with increasing invasiveness potential in last decades (Warren et al., 2001). A common reed encroachment into different wetland habitats and various plant communities is widely observed across the world (e.g. Güsewell and Klötzli, 1998; Chambers et al., 1999; Philipp and Field, 2005; Tulbure and Johnston, 2010; Liu et al., 2012; Howard and Turluck, 2013). This “expansion” of Phragmites is generally regarded as a result of disturbance (human-caused and natural), increased habitat fertility and nutrient availability and new supplies of both seed and vegetative propagules (e.g. Philipp and Field, 2005). It was also proved that the highest invasion potential is positively related to the seed viability and patch-level genetic diversity of Phragmites (Kettenring et al., 2011). It is also commonly accepted that the strongest expansion of Phragmites is associated with the exotic genotypes and alien varieties of Phragmites populations (Saltonstall, 2003). Encroachment of P. australis could seriously alter the native species assemblages and diversity of plants and animals (Vitousek et al., 1997; Gratton and Denno, 2005). As we observed in our research, the species is able to effectively compete with strong populations of T. latifolia. It was formerly observed also in North America where P. australis outcompeted T. latifolia and T. angustifolia (Chun and Choi, 2009). Despite P. australis is a native species in SW Poland it could cause a considerable unification in natural spontaneous wetland vegetation. We observe restrictions and decline of Glycerietum maximae, Typhetum angustifoliae, Scirpetum lacustris plots as well as population of B. maritimus and C. fuscus directly due to Phragmites strong expansion. So, as it was demonstrated earlier (Beltman et al., 1995), also the native species may have an invasive behaviour in restored wetland habitats. Looking for other causes of Phragmites expansion we suggest that it could be triggered not only by the fertility increase but also by lack of destructive effects of inundations. After the Great Flood in 1997, the Hydrotechnical Node Opole was completely rebuilt and adjusted to higher levels of flood water. As a result, within a period of next 15 years, the research site was flooded each year, but no significant damage in habitats was done. The reservoirs maintained their shape, no considerable shore erosion was observed and no sand or gravel material were deposited within the research site. This stable habitat condition in our opinion supported the development and consequent domination of the strongest competitor P. australis. The whole wetland ecosystem responded to that by the species diversity decrease and probably entered the “arrested succession” stage (van der Valk, 1992). This is also in line with the intermediate

disturbance hypothesis (Connell, 1978). Lack of impact caused by humans or nature could lead to a decrease of species richness and patchiness of vegetation. Such domination of common or even invasive species can be decisive for further management and development of restored ecosystem. Analysing the red-listed species distribution and richness across the research period, for sustaining the proper conservation state it seems indispensable to provide the regular destructive intervention within the Phragmites belts around the water table. 4.4. Fluctuations of red-listed species The first occurrence of red-listed species was confirmed two years after the habitat creation (P. pusillus). During 13 years of restoration both target species (B. maritimus and B. umbellatus) which gave the impulse for the conservation action were observed in artificial oxbows in the research area as well. However, their occurrence was restricted to the short period between 2003 and 2005 and early successional stages. Then, the increasing abundance and domination of P. australis outcompeted those target species. Other red-listed species were also hampered by expansion of P. australis. Potamogeton lucens, H. odorata and S. natans disappeared between 2007 and 2011. Only Spirodela polyrhiza could thrive inside shadowy Phragmites stands in shallow waters. Of course, not only common reed has exerted a negative effect on the red-listed species. Especially in open water habitats it is apparent that N. lutea benefits from increasing fertility and overgrows almost all reservoir surfaces. Our observation supports conclusion that digging artificial reservoirs as a substitute habitat for river valley plants could be an effective conservation measure, however within a restricted time span. After about 10 years without any additional support (strong inundations with erosion and new sediments, elimination of dominating species, e.g. Phragmites, N. lutea), the ecosystems tend to be dominated by the most expansive or invasive plants and not so abundant and diverse as far as conservationally valuable species are concerned. Similar results regarding the red-listed species persistence and recolonization rate were observed in other wetland and marsh restoration sites (Thom et al., 2002; Wolters et al., 2005). The results of our study do not refer to the natural oxbow lakes in surrounding areas because of the lack of well-preserved natural river old branches in the city of Opole. However, regular observations on oxbow lakes outside urbanised areas show that domination of the strongest competitors like Phragmites or N. lutea is a typical and common phenomenon. During long periods without catastrophic floods, with no visible disturbance in ground

A. Nowak et al. / Ecological Engineering 83 (2015) 125–134

133

relief of river valleys, the wetland ecosystems are going to enter the terminal successional stages and decrease in species numbers and phytocoenosis patchiness. It is worth noting that in whole reservoirs area, in between monitoring plots, other red-listed species were additionally observed: Achillea ptarmica, Batrachium circinatum, Carex pseudocyperus, Potamogeton pectinatus. They also disappeared after 11 years of monitoring, with exception of C. pseudocyperus which is still present in ecotone zone between the Phragmites or P. arundinacea stands and open water (Fig. 9).

and vanishing species of the river wetlands to support their recolonization. So, not only does the habitat need be prepared according to natural oxbow lakes example, but also the management has to imitate the flooding regime of the river.

4.5. River corridor indicators

References

River valleys are considered to be an effective corridor for dispersal of various organisms through the landscape (Gurnell et al., 1994; Puth and Wilson, 2001). It is commonly observed that many vascular plant species grow mainly or exclusively in the valleys of large rivers. This species are confined into a group of so called ‘river corridor species’ (Burkart, 2001). According to Nobis and Skórka (2014), among the 44 native river corridor species known from the Silesian section of the Oder River valley only five were recorded within the research area (R. austriaca, B. maritimus, C. ficifolium, P. supina and S. natans). Even if we exclude some extinct species from the list, such as Dichostylis micheliana or E. palustris, and take into account that the artificial oxbows are not offering suitable habitats for forest or shrub species, the number of plants typical for river valleys is significantly low. As we know from the experiments by Fischer et al. (2010), the river corridor species benefit mainly from inundations which restrict other species. Even if not, they need cyclic dynamic and strong inundations to “refresh” their habitats in terms of creation of suitable sites for settlement and recruitment (Van Looy and Meire, 2009). So, it is possible that the scarcity of this kind of plants is mainly due to lack of destructive flooding in the city area. Maybe also the crucial role has been played by the small area of studied oxbows and limited number of plant associations which could harbour different river corridor species. Restricted soil seed bank plays a significant role in the recolonization of wetland habitats by river corridor species. Many authors suggest that the soil seed bank is often an insufficient source for recolonization (e.g. Jensen, 1998). Seed dispersal is often too limited to compensate for this deficiency (Middleton et al., 2006). 5. Conclusions and management implications The presented study provides an insight into the effectiveness of riparian habitat recreation by constructing an artificial oxbow lakes within the large river valley. Despite the permanent human impact on the site (angling, recreation) and considerable abundance of alien species within the Oder valley, the created oxbow lakes were rapidly overgrown by native plants and their assemblages. The anthropophytes in considerable abundance were observed only in early successional stages and then started to decline to almost negligible numbers. It has been also proved that several target species have successfully reestablished themselves within the area, including Bolboshoenus maritimus and B. umbellatus which were the incentive to undertake the conservation project. Typical river corridor species also inhabit the created habitats. However, after reaching the maximum abundance and frequencies almost all conservation important plants declined at the end of the research. This is related to the expansion of strong native competitors like P. australis or Nuphar lutea. So, restoring just the environmental conditions may be sufficient for a limited period of time only. Without strong and dynamic flooding processes within the valley after about 10-13 years there is a need to make intervention to create new suitable habitats for rare

Acknowledgements Gratitude is owed to the Regional Directorate for Water _ for making Management in Opole and personally to Józef Kałuza this research possible by creation of artificial oxbows.


Badora, K., 2001. Srodowisko fizyczno-geograficzne. In: Koziarski, S., Makowiecki, J. (Eds.), Walory przyrodniczo-krajobrazowe Stobrawskiego Parku Krajobrazowego. Uniwersytet Opolski, Opole, pp. 11–62. Beltman, B., van den Broek, T., Bloemen, S., 1995. Restoration of acidified rich-fen ecosystems in the vechtplassen area: successes and failures. In: Wheeler, B.D., Shaw, S.C., Fojt, W.J., Robertsen, R.A. (Eds.), Restoration of Temperate Wetlands. Wiley, Chichester, United Kingdom, pp. 273–286. Berling, D.J., 1995. General aspects of plant invasions: an overview. In: Pysek, P., Prach, K., Reimanek, M., Wade, M. (Eds.), Plant Invasions: General Aspects and Special Problems. SPB Academic Publishing, Amsterdam, pp. 237–247. Botham, M.S., Rothery, P., Hulme, P.E., Hill, M.O., Preston, C.D., Roy, D.B., 2009. Do urban areas act as a foci for the spread of alien plant species? An assessment of temporal trends in the UK. Divers. Distrib. 15, 338–345. Brülisauer, A., Klötzli, F., 1998. Habitat factors related to the invasion of reeds (Phragmites australis) into wet meadows of the Swiss Midlands. Z. Ökol. Naturschutz 7, 125–136. Burkart, M., 2001. River corridor plants (Stromtalpflanzen) in Central European lowland: a review of poorly understood plant distribution pattern. Glob. Ecol. Biogeogr. 10, 449–468. Chambers, R.M., Meyerson, L.A., Saltonstall, K., 1999. Expansion of Phragmites australis into tidal wetlands of North America. Aquat. Bot. 64, 261–273. Chun, Y.-M., Choi, Y.D., 2009. Expansion of Phragmites australis (Cav.) Trin. ex Steud. (Common Reed) into Typha spp. (Cattail) wetlands in northwestern Indiana, USA. J. Plant Biol. 52, 220–228. Chytrý, M., Maskell, M.C., Pino, J., Pyšek, P., Vilá, M., Font, X., Smart, S.M., 2008. Habitat invasions by alien plants: a quantitative comparison among Mediterranean, subcontinental and oceanic regions in Europe. J. Appl. Ecol. 45, 448–458.  Chytrý, M., 2011. Vegetace Ceské Republiky. 3. Vodní A Mokradni Vegetace. Academia, Praha. Connell, J.H., 1978. Diversity in tropical rainforest and coral reefs. Science 199, 1302– 1310. Dajdok, Z., Anioł-Kwiatkowska, J., Ka˛cki, Z., 1998. Impatiens glandulifera Royle in the floodplain vegetation of the odra river valley (west poland). In: Starfinger, U., Edwords, K., Kowarik, I., Williamson, M. (Eds.), Plant Invasions: Ecological Mechanisms and Human Responses. Backhuys Publishers, Leiden, The Netherlands, pp. 161–168. Dajdok, Z., Ka˛cki, Z., 2003. Kenophytes of the odra riversides. In: Zaja˛c, A., Zaja˛c, M., Zemanek, B. (Eds.), Phytogeographical Problems of Synanthropic Plants. Institute of Botany. Jagiellonian University, Kraków, pp. 131–136. Erwin, K.L., 2009. Wetlands and global climate change: the role of wetland restoration in a changing world. Wetl. Ecol. Manag. 17, 71–84. Fischer, M., Burkart, M., Pasqualetto, V., van Kleunen, M., 2010. Experiment meets biogeography: plants of river-corridor distribution are not more stress-tolerant but benefit less from more benign conditions elsewhere. J. Plant Ecol. 3, 149– 155. Gallardo, B., Cabezas, Á., Gonzalez, E., Comín, F.A., 2012. Effectiveness of a newly created oxbow lake to mitigate habitat loss and increase biodiversity in a regulated floodplain. Restor. Ecol. 20, 387–394. Gratton, C., Denno, R.F., 2005. Restoration of arthropod assemblages in a spartina salt marsh following removal of the invasive plant Phragmites australis. Restor. Ecol. 13, 358–375. Gurnell, A.M., Angold, P., Gregory, K.J., 1994. Classification of river corridors issues to be addressed in developing an operational methodology. Aquat. Conserv. 4, 219–231. Güsewell, S., Klötzli, F., 1998. Abundance of common reed (Phragmites australis), site conditions and conservation value of fen meadows in Switzerland. Acta Bot. Neerl. 47, 113–129. Howard, R.J., Turluck, T.D., 2013. Phragmites australis expansion in a restored brackish marsh: documentation at different time scales. Wetlands 33, 207–215. Huston, M., 1979. A general hypothesis of species diversity. Am. Nat. 113, 81–101. Jensen, K., 1998. Species composition of soil seed bank and seed rain of abandoned wet meadows and their relation to aboveground vegetation. Flora 193, 345–359. Jermaczek, A., Chojnacki, I., Kołodziejska, R., 1996. Ecological And Economical Aspects Of River Transport Development. Lubuski Klub Przyrodników,
Swiebodzin. Kettenring, K.M., McCormick, M.K., Baron, H.M., Whigham, D.F., 2011. Mechanisms of Phragmites australis invasion: feedbacks among genetic diversity, nutrients, and sexual reproduction. J. Appl. Ecol. 48, 1305–1313.

134

A. Nowak et al. / Ecological Engineering 83 (2015) 125–134

Knight, S.S., Locke, M.A., Smith, S., 2013. Effects of agricultural conservation practices on oxbow lake watersheds in the Mississippi River alluvial plain. Soil Water Res. 8, 113–123. Kühn, I., Brandl, R., May, R., Klotz, S., 2003. Plant distribution patterns in Germany— will aliens match natives? Feddes Reppert. 114, 559–573. Lepš, J., Šmilauer, P., 2003. Multivariate Analysis Of Ecological Data Using Canoco. Cambridge University Press, Cambridge. Liu, B., Liu, Z., Wang, L., 2012. The colonization of active sand dunes by rhizomatous plants through vegetative propagation and its role in vegetation restoration. Ecol. Eng. 44, 344–347. Matuszkiewicz, W., 2001. Przewodnik Do Oznaczania Zbiorowisk Ro
slinnych Polski. Vademecum Geobotanicum 3. Warszawa, Wydawnictwo Naukowe PWN. May, R.M., MacArthur, R.H., 1972. Niche overlap as a function of environmental variability. Proc. Nat. Acad. Sci. USA 69, 1109–1113. Middleton, B., Van Diggelen, R., Jensen, K., 2006. Seed dispersal in fens. Appl. Veg. Sci. 9, 279–284. Mirek, Z., Pie˛ko
s-Mirkowa, H., Zaja˛c, A., Zaja˛c, M., 2002. Flowering plants and pteridophytes of poland. a checklist. In: Mirek, Z. (Ed.), Biodiversity of Poland 1. W. Szafer Institute of Botany. Polish Academy of Sciences, Kraków, pp. 442. Nobis, A., Skórka, P., 2014. River corridor plants revisited: what drives their unique distribution pattern? Plant Biosyst. doi:http://dx.doi.org/10.1080/ 11263504.2014.972999. Nobis, M., Nobis, A., Nowak, A., 2006. Typhetum laxmannii (Ubrizsy 1961) Nedelcu 1968—the new plant association in Poland. Acta Soc. Bot. Pol. 77, 325–332. Nowak, A., Nowak, S., Spałek, K., 2008. Red list of vascular plants of Opole province— 2008. Nat. J. 41, 141–158. Norman, M.A., Koch, J.M., Grant, C.D., Morald, T.K., Ward, S.C., 2006. Vegetation succession after bauxite mining in Western Australia. Restor. Ecol. 14, 278–288. Novák, J., Prach, K., 2003. Vegetation succession in basalt quarries: pattern on a landscape scale. App. Veg. Sci. 6, 111–116. Ot’ahel’ová, H., Valachovi9 c, M., Hrivnák, R., 2007. The impact of environmental factors on the distribution pattern of aquatic plants along the Danube River corridor (Slovakia). Limnologica 37, 290–302. Philipp, K.R., Field, R.T., 2005. Phragmites australis expansion in Delaware Bay salt marshes. Ecol. Eng. 25, 275–294. Poulin, M., Andersen, R., Rochefort, L., 2012. A new approach for tracking vegetation change after restoration: a case study with peatlands. Restor. Ecol. 21, 363–371. Prach, K., Pyšek, P., 2001. Using the spontaneous succession for restoration of human disturbed habitats: experience from the Central Europe. Ecol. Eng. 17, 55–62. Prach, K., Pyšek, P., Bastl, M., 2001. Spontaneous vegetation succession in human disturbed habitats: a pattern across seres. Appl. Veg. Sci. 4, 83–88. Prach, K., Pyšek, P., Šmilauer, P., 1999. Prediction of vegetation succession in human disturbed habitats using an expert system. Restor. Ecol. 7, 15–23. Puth, L.M., Wilson, K.A., 2001. Boundaries and corridors as a continuum of ecological flow control: lessons from rivers and streams. Conserv. Biol. 15, 21–30. Pyšek, P., Prach, K., Šmilauer, P., 1995. Invasion success related to plant traits: an analysis of czech alien flora. In: Pyšek, P., Prach, K., Rejmánek, M., Wade, P. (Eds.),

Plant Invasions: General Aspects and Special Problems. SPB Academic Publishing, Amsterdam, pp. 39–60.
ski, P. (Eds). 2000. Atlas niv Odry. WWF Deutschland. Rast, G., Obrdlík, P., Nieznan Saltonstall, K., 2003. A rapid method for identifying the origin of North American Phragmites populations using RFLP analysis. Wetlands 23, 1043–1047. Starfinger, U., Edwards, K., Kowarik, I., Williamson, M., 1998. Plant Invasions: Ecological Mechanisms And Human Responses. Backhuys, Leiden, The Netherlands. StatSoft Inc, 2010. STATISTICA for Windows. Computer Program Manual. StatSoft, Inc., Tulsa, OK: 2300 East 14th Street, Tulsa. Thom, R.M., Ziegler, R., Borde, A.M., 2002. Floristic development patterns in a restored Elk River estuarine marsh, Grays Harbor, Washington. Restor. Ecol. 10, 487–496. Tockner, K., Stanford, J.A., 2002. Riverine flood plains: present state and future trends. Environ. Conserv. 29, 308–330. Tokarska-Guzik, B., 2003. Habitat preferences of some alien plants (kenophytes) occurring in poland. In: Zaja˛c, A., Zaja˛c, M., Zemanek, B. (Eds.), Phytogeographical Problems of Synanthropic Plants. Institute of Botany. Jagiellonian University, Kraków, pp. 75–83. Tokarska-Guzik, B., 2005. The Establishment And Spread Of Alien Plant Species (kenophytes) In The Flora Of Poland. Wyd. Uniw., la˛skiego, Katowice. ter Braak, C.J.F., Šmilauer, P., 2002. Canoco Reference Manual And Canodraw For Windows User’s Guide: Software For Canonical Community Ordination (version 4.5). Microcomputer Power, Ithaca, New York. Tomiałoj
c, L., 1993. Ochrona Przyrody I
srodowiska W Dolinach Nizinnych Rzek Polski. IOP PAN, Kraków. Tulbure, M.G., Johnston, C.A., 2010. Environmental conditions promoting nonnative Phragmites australis expansion in Great Lakes coastal wetlands. Wetlands 30, 577–587. Warren, R.S., Fell, P.E., Grimsby, J.L., Buck, E.L., Rilling, G.C., Fertik, R.A., 2001. Rates, patterns, and impacts of Phragmites australis expansion and effects of experimental Phragmites control on vegetation, macroinvertebrates, and fish within tidelands of the lower Connecticut River. Estuaries 24, 90–107. Wolters, M., Garbutt, A., Bakker, J.P., 2005. Salt-marsh restoration: evaluating the success of de-embankments in north–west Europe. Biol. Conserv. 123, 249–268. van der Valk, A., 1992. Establishment, colonization and persistence. In: GlennLewin, D.C., Peet, K., Veblen, Th.T. (Eds.), Plant Succession and Prediction. Chapman & Hall, London, pp. 60–102. Van Looy, K., Meire, P., 2009. A conservation paradox for riparian habitats and river corridor species. J. Nat. Conserv. 17, 33–46. Vitousek, P.M., D'Antonio, C.M., Loope, L.L., Rejmanek, M., Westbrooks, R., 1997. Introduced species: a significant component of human-caused global change. New Zeal. J. Ecol. 21, 1–16. Zaja˛c, M., Zaja˛c, A., 2009. The Geographical Elements Of Native Flora Of Poland. Laboratory of Computer Chorology, Institute of Botany Jagiellonian University, Kraków. Zaja˛c, M., Zaja˛c, A., Tokarska-Guzik, B., 2009. Extinct and endangered archaeophytes and the dynamics of their diversity in Poland. Biodiv. Res. Conserv. 13, 17–24.