Prospects of fen restoration in relation to changing land use—An example from central Poland

Landscape and Urban Planning 97 (2010) 249–257

Contents lists available at ScienceDirect

Landscape and Urban Planning journal homepage: www.elsevier.com/locate/landurbplan

Prospects of fen restoration in relation to changing land use—An example from central Poland ˙ c , Ab P. Grootjans d,g , Wiktor Kotowski c,e , Rudy VAN Diggelen f Agata Klimkowska a,b,c,∗ , Paulina Dzierza a

Community and Conservation Ecology Group, Centre for Ecological and Evolutionary Studies, University of Groningen, P.O. Box 14, 9750 AA Haren, The Netherlands Institute for Land Reclamation and Grassland Farming (IMUZ), Falenty, Al. Hrabska 3, 05-090 Raszyn, Poland Wetland Conservation Centre, Raszy´ nska 32/44 App. 140, 02-262 Warsaw, Poland d Center for Energy and Environmental Studies, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands e Department of Plant Ecology and Nature Protection, Institute of Botany, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland f Ecosystem Management Research Group, University of Antwerp, Department of Biology, Universiteitsplein 1, B-2610 Wilrijk, Belgium g Institute for Water and Wetland Research Radboud, University of Nijmegen, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands b c

a r t i c l e

i n f o

Article history: Received 23 September 2009 Received in revised form 15 June 2010 Accepted 20 June 2010

Keywords: Drainage Fen system Groundwater discharge Water budget

a b s t r a c t We carried out an eco-hydrological analysis to evaluate the most important effects of land use changes on the hydrological functioning of a fen system in Poland. We measured water levels (hydraulic heads) and water flow along a transect through the study area and also analysed land use changes using historical maps. Major hydrological changes occurred after c. 1950 when a dense drainage network was constructed and in the last decade when large fishponds were built. Nowadays, water levels in most of the fens and fen meadows are too low and the fluctuations too large for a long-term preservation of fen ecosystems. The mean water tables range from 0.3 to 0.8 m below soil surface with fluctuations from 0.7 up to 1.5 m. A second important cause of the hydrological changes of the system was the afforestation of the adjacent infiltration areas leading to increased evapotranspiration and a decreased groundwater flow to the wetlands. Finally, a recent increase in groundwater abstraction for agricultural purposes has probably lowered the groundwater even further. We conclude that a full restoration of the fen is not possible under the present conditions. An alternative restoration goal could be conservation and restoration of species-rich fen meadows, but also then improving the hydrological conditions will be necessary. While the focus is often on the local factors influencing the restoration prospects of a fen system, the regional processes are at least equally important. In this paper we discuss an importance of both local and regional factors. © 2010 Elsevier B.V. All rights reserved.

1. Introduction In the presented study we discuss the prospect for restoration of groundwater fed fens with altered hydrology and consider both local and regional causes of fens degradation. Such fens and fen meadows provide multiple ecosystem services and host a high biodiversity (Zedler, 2000; Millennium Ecosystem Assessment, 2005; van Diggelen et al., 2006), but most of these ecosystems have disappeared from the European landscape and the remaining ones are often highly degraded (Joosten and Clark, 2002). The loss of undisturbed mires in the 20th century in Poland was estimated to be more than 80% (Kotowski and Piórkowski, 2003) whereas grasslands on severely degraded peat soils occupy over 1,000,000 ha ´ at the same time (Grzyb and Pronczuk, 1994; Jankowska-Huflejt,

∗ Corresponding author. Present address: Alterra, Centrum Landscape, Postbus 47, 6700 AA Wageningen, The Netherlands. Tel.: +31 0 317 481683. E-mail address: [email protected] (A. Klimkowska). 0169-2046/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.landurbplan.2010.06.009

2006). Conservation of the remaining undisturbed sites has gained political support all over Europe during the last decades and efforts to restore disturbed sites are increasing in numbers (Lamers et al., 2002; Klimkowska et al., 2007a). Fens and fen meadows rely heavily on groundwater supply from the surrounding landscape (Wassen et al., 1990, 1996; Jansen et al., 2000). A good understanding of past and present landscape arrangement is essential for effective conservation and restoration of these vulnerable ecosystems (Grootjans and van Diggelen, 1995; van Diggelen et al., 2006). Different land use systems may affect infiltration rates and indirectly determine the feasibility of restoration targets. Explicit and quantified relations between land use practices in a catchment and fen restoration prospects are difficult to identify and often stay unspecified. This knowledge is urgently needed to formulate adequate plans for conservation and restoration of peatlands as elaborated in European and national biodiversity action plans. This is especially relevant for large and highly degraded peatlands in Central and Eastern Europe. To gain more insight in the effects of land use practices, we studied a typical

250

A. Klimkowska et al. / Landscape and Urban Planning 97 (2010) 249–257

example of a degraded fen in central Poland, where many various changes in the hydrology have occurred. This case study can thus serve as template for many similar areas. We selected the Całowanie fen system, together with its infiltration area, where various land use types may potentially affect the outcome of restoration activities. These land use types include low intensity agriculture (hay meadows), nature conservation, forestry, water abstraction for agriculture (greenhouse production), fishery and peat extraction. The study area still has a high nature conservation value, but the quality is decreasing and parts of the peatland ´ are already severely degraded (Jabłonska and Pawlikowski, 2004; Klimkowska et al., 2007b). A re-establishment of a low intensity management regime in this area since 2004 had only limited effect (Wetlands Conservation Centre, unpublished data), possibly because of changes in the hydrological system outside the project area. It is a typical situation where authorities have to find solutions to potentially conflicting land use practices. On the one hand regional authorities are committed to national policies to conserve and also improve conditions of legally protected fen meadow species, while at the same time they stimulate multifunctional use of the area (by farms, forestry, nature conservation, fishery). The goal of the presented study is to identify major land use changes and resulting hydrological changes in the Całowanie fen system and to evaluate the prospects for its restoration. We studied three main questions: 1. What have been the most important land use changes that occurred in the Całowanie fen system since 1900? 2. Does groundwater discharge still occur in the study area? 3. Can we restore the original hydrology associated with fen system? If not, what are the prospects for restoring meadows with a high richness of species associated with fens or fen meadows in this location?

suggest eolian processes and regular flooding by the Jagodzianka ˙ River or Wisła River (Zurek, 1990; Schild et al., 1999). The peat descriptions show that in the past the vegetation was dominated by Carex lasiocarpa and C. diandra, with frequent occurrence of C. rostrata, C. limosa, C. paradoxa, Menyanthes trifoliata, Phragmites australis, and brown mosses. Tall sedges and sedge-reed beds occurred at the fen borders, while alder wood dominated the veg˙ etation in the northern part (Zurek, 1990; O´swit and Dembek, 2001). The northern part of the peatland is currently the wettest, because a road bank obstructs water outflow (O´swit and Dembek, 1984).In the past, the local farmers were extracting the peat for fuel. This small-scale extraction was done by digging shallow peat-cuts (0.5–1.0 m deep) and hardly influenced the hydrological situation since these peat-cuts were not connected to the drainage ditches and did not result in draining meadows in the surroundings. When regularly mown, these peat-cuts became a refuge for fen plant species when the fen area was reclaimed and drained (Podbielkowski, 1960; Klimkowska et al., 2007b). Gradual land abandonment, starting from 1980s, resulted in willow encroachment in fen meadows and development of tall herbs and birch-alder wood in part of the area (O´swit and Dembek, 1984). In 2004, a restoration project was started to maintain the valuable habitats of fen meadows and to stop further degradation of peatland. The project was carried out in the eastern part of the area (c. 7 ha) and consisted of shrub removal (2004–2005), reintroduction of annual mowing and small-scale rewetting (2004). 2. Materials and methods We present here a rather simple and low-cost method that can be used easily to investigate system functioning and system transformation.

1.1. Study area

2.1. Eco-hydrological analysis

Całowanie fen is located on the slopes of the Wisła River valley ˙ at the base of an upland moraine (Zurek, 1990; O´swit and Dembek, 2001) in central Poland (52◦ 00 47 N, 21◦ 20 24 E), and is recognized as a Natura 2000 site. The mean annual rainfall in the area is 555 mm (Mioduszewski, W. Falenty station). The annual precipitation (station Warsaw—airport) was 523 mm in 2004, 490 mm in 2005, 479 mm in 2006, and 590 mm in 2007.The mean annual temperature in the region is 7.4 ◦ C (Olszewski, 2003). The long-term average sum of potential evapotranspiration in central Poland is 549 mm ˙ ´ 2005). A sum of actual measured (Kozuchowski and Degirmendˇzic, evapotranspiration during the growing season in the similar vege˛ tation ranges between 450 and 490 mm (Łabedzki et al., 2003).The large difference in height between upland and fen (c. 40 m) and impermeable layers of the moraine result in intensive groundwater discharge into the fen from the East. The main direction of groundwater flow is from East to West. Run-off water from the upland ˙ forms creeks, flowing also from East to West (Zurek, 1990; O´swit and Dembek, 1984). The middle and northern parts of the fen dis´ charge water to the channelized River Jagodzianka (Bielinskiego Channel) at the western border of the fen. The middle and southern parts of the peatland were always fed by calcareous groundwater, which can be derived from thick low sedge-brown moss peat deposits with calcareous gyttja lay˙ ers (O´swit and Dembek, 1984, 2001; Zurek, 1990). Paleoecological records suggest that peat formation started in the Alleröd period (12,000–11,000 year BP), from shallow groundwater pools, leading to the development of oligotrophic to mesotrophic vegetation (Schild et al., 1999; O´swit and Dembek, 1984). Numerous sand and clay layers in the peat profile and the presence of parabolic dunes

We investigated the hydrological system by measuring water levels (hydraulic heads) and flow velocity. We also reconstructed the historical development in the area by analysing various cartographic sources including the map of the Mazovia district in the Atlas of the Polish Kingdom (Atlas Królestwa Polskiego) by J. Kolberg (1826–1827, 1:126,000), the Austrian military map (c. 1912, 1:200,000), maps of 1933 (Military Geographic Institute, 1:25,000), maps of 1960s (Rudnicka, 1961; The National Geodetic and Cartographic Service 1:25,000), and recent topographical maps (The National Geodetic and Cartographic Service, 1996, 1:25,000, 1:50,000). Field studies were carried out from 2004 until 2007, with focus on a cross-section between the villages Podbiel and Całowanie (Fig. 1), where we installed 10 piezometers in a transect perpen´ dicular to the Bielinskiego Channel. The piezometers consisted of a pvc pipe (diameter 25 mm) and filter (30 cm long, 0.5 mm × 10 mm perforated pvc pipe), with four layers of thin mesh gaze around it. The filters were isolated with filter sand (1–1.6 mm grain). The space around the tubes was sealed with bentonite. The piezometers were placed at least 50 m away from the main ditch and down to the mineral subsoil (2–4 m depth). In three locations, we set up paired piezometers in the sandy subsoil and in the peat. The shallow piezometers placed in the peat were 1–1.5 m deep. Piezometers were monitored every 2–3 weeks from April through October (2004–2007). We also measured elevation along the crosssection through the peatland. Additionally, we analysed the groundwater (in 2004) from several locations within the peatlands and around, for ions HCO3 − , Ca2+ , Mg2+ , Fe3+ ,Cl− , SO4 2− , PO4 3− , electric conductivity (EC) and pH, to assess the presence of mineral-rich seepage (described at

A. Klimkowska et al. / Landscape and Urban Planning 97 (2010) 249–257

251

Fig. 1. Location of study area within the Całowanie fen peatland (A). Also the extent of the infiltration area and data on water abstraction were presented. Layout of the transect study (B) (fragment of a topographic map, The National Geodetic and Cartographic Service, 1996, 1:25,000).

Klimkowska, 2008). Groundwater was sampled from piezometers. Water samples were taken after emptying the piezometers (by pumping away the stagnating water) to allow refilling with fresh groundwater. The samples were analysed several days after sampling, thus reduced forms and complexes (e.g. Fe2+ ) could not be detected. Water velocity was measured across ditch profiles in spring and summer 2005 with a current-meter OTT Nautilus 2000 (Swiatek et al., 2008), and water flow was calculated and summed over the ditch profile. The flow was measured during a period of high and low water level in the Wisła River (April and June 2005, respectively, data of the Institute of Meteorology and Water Management), which were most probably highest and lowest water flows of that year. As there is no other drainage infrastructure, connected to the ponds accept of the main ditch (central ditch) and no other minor ditches in this section of the central ditch, we assumed that the difference between water flow before and after ponds is a volume of groundwater discharge from the ponds. For a rough estimation of the water budget, we calculated the influx of water using data on precipitation (555 mm year−1 ), potential evapotranspiration (pEv, based on Penman formula) (532 mm during the growing season period April–September) and esti-

mated evapotranspiration for the meadows and forests (based on literature). Evapotranspiration was estimated separately for the infiltration area (upland) and peatland area (corrected for the percentage of forested area and open meadow vegetation in both). The actual evapotranspiration of meadow vegetation was estimated as: pEv/aEv = 1.2, where pEv—potential evapotranspiration, aEv—actual evapotranspiration (Jaksic et al., 2006; Ryszkowski and ˛ Kedziora, 1987). The evapotranspiration of forest (pine forest and alder or birch-alder forest) was estimated to be 550 mm (Reynolds and Thompson, 1988; Stephanson, 1998). We also estimated the percentage of forested area in the beginning of the century and assumed the same sum of precipitation as nowadays, but ˙ ´ 40 mm lower evapotranspiration (Kozuchowski and Degirmendˇzic, ˙ 2005). Kozuchowski and Degirmendˇzic´ (2005) showed significant increase in potential evapotranspiration in central Poland with on average 44 mm higher evapotranspiration at the end of 20th century, compared with the 1950. The change in temperature and precipitation patterns in central Poland shows a clear trend of warming (Degirmendˇzic´ et al., 2004). As the data from before 1950 are not available and it is unlikely that this trend could be extrapolated into the past, we assumed that the evapotranspiration rates in the beginning of 20th century were similar to these in

252

A. Klimkowska et al. / Landscape and Urban Planning 97 (2010) 249–257

Fig. 2. System changes of the Całowanie fen (scale not maintained): (A) natural situation of mire (<19th century), (B) semi-natural situation (c. 1850), (C) semi-natural situation (c. 1900), and (D) present situation (2004–2007).

the 1950 ties. The water budget was defined as: P − aEv = Q, where P—precipitation, aEv—actual evapotranspiration, Q—outflow.

3. Results 3.1. System functioning

2.2. Data analysis We calculate the mean phreatic level with standard deviation and amplitude (maximum minus minimum observed level, further referred to as water table fluctuations). A t-test (for dependent samples) was used to detect differences between water levels in paired piezometers. Cumulative frequency lines were calculated for the growing season (April–October) to characterize water level requirements for the vegetation. We used data from the best preserved fen meadows in the same area as reference meadows data. Unfortunately there was no similar fen area with close-to-original hydrological system present near-by and no detailed hydrological data of study area from the past. More or less pristine fens in East Poland had different origin and functioning than our study area, and, therefore, data from such areas could not be used as a reference. We estimated the quantities of water pumped by greenhouse complexes near Janów, Piotrowice, Karczew (west of peatland) and by groundwater abstraction facilities near Osieck (east of peatland) (Fig. 1A). We used the official water use permits for production purposes (issued in the past 10 years) to assess the quantity of ground water abstracted.

Natural fen: Before human interference, the infiltration area was probably forested, but the fen area was open, with alder wood present along the borders and in the northern part of the mire (Fig. 2A). Later, the infiltration area was kept open by farmers. In the 19th century farmers had already connected the little streams that drained a seepage area to the river (map of 1926, Fig. 2B). The area was still in a relatively natural state and the river meandered through the peatland. Semi-natural fen meadows: The River Jagodzianka was regulated around 1900. Fen meadows that developed in a large part of the study area were present until c. 1950 (maps of 1912, 1933; Rudnicka, 1961). Many drainage ditches were constructed between 1960 and 1980 and this resulted in a major transformation of the system. O´swit and Dembek (1984) reported that after these hydrological changes the water levels in wells on the upland used by farmers dropped 1.2–1.5 m. The vegetation developed in this period into drier, moderately eutrophic fen meadows types (Calthion palustris, Molinion caeruleae alliances) (Podbielkowski, 1960; Rudnicka, 1961, Fig. 2C). Later these meadows were deeply drained and probably fertilized, and vegetation of the Alopecurion pratensis and

Fe3+ (mg L−1 )

0.04 – 0.88 – – – – 1.85 0.78 0.46 – – – 0.12 1.33 – 0.001 2.93 3.49 1.42 1.89 – 6.15 4.89 4.03 3.38 9.16 – 1.23 1.41 – 3.74 4.54 0.88 7.43 6.76 7.35 – 6.68 7.52 9.45 9.32 16.84 17.6 16.67 8.74 4.37 8.23

Mg2+ (mg L−1 ) Ca2+ (mg L−1 )

33.22 47.00 68.38 58.55 58.59 – 61.19 78.20 65.77 69.76 123.61 152.20 116.89 76.31 – 56.87 15.37 5.98 2.60 5.27 1.74 – 1.78 1.29 2.08 2.99 2.02 1.20 5.85 7.09 2.44 0.99 28.09 43.79 63.68 57.87 10.34 – 5.60 4.69 3.16 1.44 6.50 4.29 2.17 13.85 – 14.09 33.09 16.45 31.76 23.21 6.67 19.10 7.27 19.98 7.85 9.71 11.57 9.67 6.75 20.20 14.47 10.98

Cl− (mg L−1 ) HCO3 − (mg L−1 )

24.4 84.55 103.7 131.27 196.79 142.13 212.5 253.03 267.40 267.91 450.06 557.8 453.84 264.98 391.86 208.01 6.9 6.2 6.11 6.76 7.5 7.26 7.43 7.02 7.26 7.11 7.25 6.74 7.21 7.8 7.08 7.7

pH (field) EC25 (␮S cm−1 )

419 286 364 428 348 407 373 452 445 445 706 866 706 494 671 378

K+ (mg L−1 )

In the mineral upland (east of peatland, piezometer 1) water tables were relatively low below the surface (mean ± SD level 0.77 ± 0.17 m), with fluctuations of 0.76 m. In the restoration area in the eastern part of the peatland (piezometers 5–6), water tables were relatively high and ranged from 0.11 ± 0.17 m to 0.30 ± 0.22 m

c. 4650 2685 2609 2370 2370 2196 2196 2087 1913 1913 1696 1696 1152 804 196 0

SO4 3− (mg L−1 )

3.2. Water tables

Distance (m)

Arrhenatherion elatioris alliances developed (O´swit and Dembek, 1984). Present situation: In the 1990s the central ditch from Podbiel to Całowanie villages was deepened and fishponds were dug in the centre of the peatland (Fig. 2D). These fishponds (3.5–4 m deep) have been excavated to sandy subsoil and, since they were connected to the drainage network, they drained surrounding meadows. A drop in water tables of c. 0.5 m was reported in the upland areas (pers. comm. local farmers). We estimate that between 1960 and 1980 summer water tables in the central part of the peatland have dropped c. 30 cm (Rudnicka, 1961; O´swit and Dembek, 1984) and after 1980 they have dropped an additional 30–65 cm. From the mid-1980s and 1990s onwards, degraded species-poor meadows developed, because of deep drainage (O´swit and Dembek, 1984; Klimkowska et al., 2007b).

Table 1 ´ Results of chemical analysis of water. Symbols: distance–distance to the Bielinskiego channel (W–E);—no data.

Fig. 3. (A) Surface level and water levels. We presented average for spring (April–May) and summer (June–August) as well as annual mean (upper graph). Error bars indicate SD. (B) The distribution of the duration lines (lower graph) was presented for local reference fen meadows (location 4–6), meadows influenced by the river flooding (location 10) and degraded meadows (location 8). Graphs are based on data of 4 years of observations.

Well in upland areas on mineral soils 1 2 3 Groundwater 3a (deep) 4 4a 5 6 6 (6a) 7 7a 8 9 10 Bielinskiego channel

PO4 3− (mg L−1 )

A. Klimkowska et al. / Landscape and Urban Planning 97 (2010) 249–257

253

254

A. Klimkowska et al. / Landscape and Urban Planning 97 (2010) 249–257

Fig. 4. Water flux in the ditches measured in April (A) and June (B) 2005. The area in black indicates a position of ‘fish ponds’ and area in grey a position of sand dunes. ‘?’ —water flow was not measured.

below soil surface, with fluctuations of 0.75 m (Fig. 3A). The shallow peat-cuts, with the fen meadow vegetation are c. 35 cm lower than the surroundings (mean ± SD: 97.31 ± 0.10 m vs. 97.65 ± 0.18 m a.s.l.). In the central part of peatland (piezometer 7–8), water tables were much lower (0.58 ± 0.28 and 0.83 ± 0.25 m below surface, respectively), with large fluctuations (1.25 and 1.1 m, respectively). ´ Near the Bielinskiego Channel, the water levels were higher again (water table 0.27 ± 0.28 m below soil surface), but the fluctuations were large (1.48 m). In paired piezometers (point 4, 6 and 7, location presented on Fig. 1), the hydraulic heads in the shallow piezometers were higher than in the deep ones, which indicate prevailing infiltration conditions. In point 4 there was 2.3 cm difference (t = −6.59, p < 0.0001), in point 6, 2.5 cm difference (t = −3.65, p < 0.001) and in point 7, 15.9 cm difference (t = −6.11, p < 0.0001). However, the hydraulic head in the deepest piezometer (point 3, 5 m deep) was above the soil surface (Fig. 3A). The cumulative frequency duration lines have been grouped into three categories: well developed reference meadows, flooded meadows, and degraded meadows (Fig. 3B). In the fen meadows the water tables were above or close to the surface in spring, indicating

a temporary discharge of groundwater, but in summer the water tables dropped to 25–30 cm below the surface. The duration lines of the degraded meadows in the central part of the area indicate that their water level regime is out of the range of fen meadows and, therefore, regeneration of the fen meadows here is unlikely. The duration lines there indicated an infiltration pattern, similar to the one on the mineral area, east of the peatland (not presented ´ here). The flooded meadows near the Bielinskiego Channel partly overlapped with the duration line of the reference meadows, but they showed lower water tables during most of the season, due to drainage effect of the nearby river (Fig. 3B). We found a relatively high pH of groundwater (above 7.0), associated with high values of EC25 , and high concentrations of HCO3 − , Fe3+ and Ca2+ in the peatland area, indicating presence of mineralrich groundwater. The water composition in most of the peatland was similar to the local groundwater reference (piezometer 3A, Table 1), indicating in-flow of deep groundwater in the area. Water from upland areas and from the eastern edge of peatland contained relatively high Cl− and SO4 2− concentrations (similar as river water), which suggested groundwater pollution. In the central part of the peatland Cl− and SO4 2− concentrations were low. In the peat-

Table 2 ´ Estimated water budget for the central part of Całowanie fen (A) and for entire part of peatland, which is drained by the Bielinskiego Channel (B). Symbols: S—estimate surface area; P—precipitation; aEv—estimated actual evaportranspiration, P − aEv—surplus of water infiltrating to the groundwater (100% refers to the past situation), Q—measured outflow from drainage. # Estimated in April 2005; ∞ estimated in June 2005; ˆ estimated in summer 1984 (O´swit and Dembek, 1984). Vales for P, aEv, P − aEv and Q are given in m3 year−1 × 106 . S (km2 )

% forested 1912

% forested 2000

P

aEv 1912

aEv 2000

17.66 8.29

15.3 6.75

16.56 6.99

P − aEv 1912

P − aEv 2000

Q

A Infiltration area Peatland Sum

31.81 14.94

50% 30%

72% 23%

2.37 1.57 3.91

1.09 1.30 2.39

100%

61%

7.26 1.85 9.11 100%

2.89 1.42 4.32 47%

7.24# 3.76∞ 5.26ˆ

B Infiltration area Peatland Sum

88.19 21.37

45% 42%

74% 42%

48.94 11.86

41.68 10.02

46.05 10.44

12.37#

A. Klimkowska et al. / Landscape and Urban Planning 97 (2010) 249–257

land area, concentrations of PO4 3− in the groundwater were higher than in the mineral upland (c. 0.8 mg L−1 vs. 0.04 mg L−1 ). The values of EC25 were higher than 300 ␮S cm−1 along almost the entire transect, with highest values (up to 700 ␮S cm−1 ) in the central part of the peatland. 3.3. Water fluxes in the central part of the peatland The water fluxes measured in the main ditches in spring and summer indicated large changes in water outflow (Fig. 4). The central ditch Podbiel–Całowanie contributed much to the total outflow, especially in summer. The summer outflow values here were 78% of the spring value, indicating a very stable supply of groundwater. The water flow in this central ditch increased 3–4-fold after passing the fishponds, indicating a large water discharge from these fishponds. Based on mean flow measurements from these ponds we estimated an annual loss from the groundwater system of about 0.7 × 106 m3 year−1 . Water discharge from the restoration areas was very small. The small-scale rewetting measures in the restoration areas (several wooden dams in a small ditch, with water rise of 40 cm in total) increased the water level in the spring, however, they could not prevent a considerable drop in water level in summer. These measures were thus insufficient for increasing groundwater discharge and for providing more stable hydrological conditions. 3.4. Water budget The water budget for the study area was estimated for the conditions of 1912 and for the present situation (Table 2). Our results showed that on an annual basis, the outflow in the area mainly consisted of groundwater from the mineral upland (east of the peatland) and possibly from some deeper aquifers. Land use changes, especially an increase in the forested areas resulted in increased evapotranspiration. The calculated reduction in infiltration was as large as 40% (Table 2). We found that water abstraction in the surroundings of peatland was considerable. Water extraction occurred from sandy layers, at 6–15 m depth, from an aquifer that has hydraulic connection to the peatland. The water extraction from this shallow aquifer amounted to approximately 0.75 × 106 m3 year−1 , which was 17% of the yearly replenishment of the groundwater body connected to the central and northern part of the peatland (see Fig. 1A and Table 2). 4. Discussion and conclusions 4.1. Land use changes and their impact on the fen system Although before the 20th century human activities, such as cutting natural forest and slight drainage of meadows, have had an impact on the Całowanie fen system, the most profound impacts started rather recently. During the last century large-scale impacts occurred due to the regulation of the Jagodzianka River and Wisła River and the construction of an intensive drainage network. These activities have resulted in lowering of the groundwater tables, leading to a conversion of fens into fen meadows. The next important change was the large-scale planting of pine forests in the infiltration area and the invasion of willow and alder shrubs in the abandoned meadows, which resulted in increased evapotranspiration (Vertessy, 2001; Huxman et al., 2005; van der Salm et al., 2006; Wassen et al., 2006). Removal of trees and shrubs from fens was found to limit evapotranspiration even by 100–170 mm year−1 and result in raising water tables (Jauhiainen et al., 2002; Huxman et al., 2005). Our estimates of the actual evapotranspiration in meadows (443.3 mm in vegeta-

255

tive period) are similar to values given by other authors (Bavina, 1967; Pribar and Ondok, 1980) and measured in wet meadows and marshes (475–490 mm in West Russia; 400–525 mm West Poland) ˛ (Reynolds and Thompson, 1988; Łabedzki et al., 2003). Evapotranspiration rates of pine forests usually amount up to c. 500–580 mm in climatic conditions similar to ours, with higher values from this range in young (40–60 year) pine stands (Reynolds and Thompson, 1988; Stephanson, 1998). Our water budget estimates suggested that the groundwater recharge has decreased with c. 40% since the beginning of the century. The hydrological conditions have changed further in the last decade, both through changes internal to the fen (digging of fishponds) and to external processes (groundwater abstraction). The lowering of the groundwater levels was largest in the central part of the area, around the fishponds. Excavation into the mineral subsoil and connection of the ponds to the drainage network has resulted in a short-circuit between ground and surface water systems. The large water outflow from the fishponds has resulted in desiccation and degradation of meadows in the surroundings and drainage effect on fen meadows in the eastern part of the area. Regional water use by large-scale horticulture, industry and for drinking water has also increased significantly over the last decade to a level of almost 20% of the yearly groundwater recharge. Only large and recent water extraction facilities were included in our assessment, probably leading to under-estimation of the real figures. Especially greenhouse horticulture (e.g. tomato production) may consume large amounts of water (c. 1 m3 m−2 year−1 , pers. comm. Dr W. O´swiecimski, Grodan, Poland). A further growth of the human population, together with the anticipated increase in life standard may raise this demand further and therefore, impose serious threats to groundwater-depended ecosystems in the region and Europewide (van Diggelen et al., 1994; Bragg and Lindsay, 2003; Grootjans and Wołejko, 2007; Banaszuk and Kamocki, 2008). Further hydrological research, using quantitative hydrological models, is highly recommended in order to evaluate the seriousness of these threats. 4.2. Feasibility of alternative restoration targets A continuous supply of mineral-rich groundwater is necessary to restore a groundwater fed fen system (van Diggelen et al., 1991, 1994; Zedler and Kercher, 2005) and this is no longer the case in Całowanie fen. The water tables are far below those in reference sites, where they do not drop any further than 10–20 cm below surface (De Mars et al., 1996; Wierda et al., 1997; Wassen and Olde Venterink, 2006). In the restoration area the fluctuation pattern of the water table corresponds better with that of fen meadows. However, under such conditions a gradual disappearance of the typical fen species can be expected (De Mars et al., 1996; Wierda et al., 1997). The prospects for restoration are most promising in the eastern part of the study area, although the conditions here are still sub-optimal in comparison to reference communities (Grootjans and ten Klooster, 1980). Water levels in the central part of the peatland were far too low for fen meadows and point to strong infiltration. Infiltration rather than exfiltration during most of the year in the top peat layer eventually results in increasing influence of rainwater and a decrease of the soil base saturation by leaching. This causes leaching of cations (Ca, Fe) from the soil exchange complex and eventually leads to acidification (van Diggelen et al., 1991; Beltman et al., 2001). High HCO3 − , Ca2+ , Fe3+ concentrations and low concentrations of SO4 2− and Cl− in the eastern and central part of the peatland, indicated discharge of mineral-rich groundwater (van Diggelen et al., 1996; Wassen et al., 1996). High calcium and iron concentrations were proposed as key-factors for maintaining a high base saturation of the soil and protecting against acidification and eutrophication (Kemmers et al., 2003). A high concentration of SO4 2− and Cl− in the

256

A. Klimkowska et al. / Landscape and Urban Planning 97 (2010) 249–257

upland areas and in the eastern edge of peatland indicated pollution, possibly from farms. In the central part of the peatland SO4 2− and Cl− concentrations were low, which also indicated discharge of clean, mineral-rich groundwater (van Diggelen et al., 1996; Wassen et al., 1996; Trepel and Kluge, 2002). Similar to other authors, we found relatively high concentrations of PO4 3− in the groundwater in the degrading fen meadows, compared to much lower values that were measured in the more pristine fens (Wassen et al., 1996). ´ An increasing influence of river water (Bielinskiego Channel) was indicated by increasing concentration of SO4 2− , Cl− and PO4 3− in the groundwater (Wassen et al., 1996). Intensive drainage also leads to peat compaction and soil subsidence, which for fen peat in our climatic conditions has been estimated to be up to 20 mm year−1 (Armentano and Menges, 1986; Eggelsmann et al., 1993; Ilnicki and Zeitz, 2003). Very likely over 40 years this has resulted in a subsidence of c. 80 cm and an associated decrease in capillary water rise and hydraulic conductivity (Brandyk et al., 2003). Hence, rising water levels in the central part of the peatland might not result in restoring the original water flow through the peat body but instead lead to surface flooding and creation of eutrophic shallow lake (Richert et al., 2000; Trepel and Kluge, 2002; Timmermann et al., 2006; Tiemeyer et al., 2006). A feasible target than might be to prevent further soil degradation and CO2 emissions. Limited restoration prospects of the fen system can be ascribed to changing land use. Until recently we were mainly concerned with the negative effects of direct changes within the fen such as drainage, peat extraction and/or fish production in artificial ponds. The present study shows how external land use changes also affect the conservation status and restoration prospects through changes in hydrology. Moreover, a fen system reflects the longterm processes and this implies that historic landscape conditions also determine the present status of a fen. Contrary to the present paradigm of beneficial multifunctional land use we have shown a case where different types of land use compete for space and resources (water). Optimising the conditions for one type of land use puts constraints on restoration of the other one and vice versa. Instead of trying to combine incompatible uses such as intensive agriculture and fen meadow conservation we suggest to choose and optimise the conditions for that particular function. What is needed here is a real choice for sustainable use of this peatland area. This requires planning and research on the level of the water catchment as a whole. The low intensity agriculture (including organic agriculture) combined with the recreational and water (& carbon) retention services should be stimulated. In the areas with high nature values a limited land use should be allowed. A fraction of the drainage facilities, which are not necessary for low intensity meadow use, could be removed. This would result in more water retention and partial rewetting of the area, beneficial for biodiversity. Stricter control and limitation of the groundwater use would be desirable. Also more control of land use changes, with sound analysis of the impact on the fen ecosystem is recommended. The discussed area is designated as a Natura 2000 site and hopefully the planning and land development procedures will be adapted.

References Armentano, T.V., Menges, E.S., 1986. Patterns of change in the carbon balance of organic soil—wetlands of the temperate zone. J. Ecol. 74, 755–774. Banaszuk, P., Kamocki, A., 2008. Effects of climatic fluctuations and land-use changes on the hydrology of temperate fluviogenous mire. Ecol. Eng. 32, 133–146. Bavina, L.G., 1967. Refinement of parameters for calculating evaporation from bogs on the basis of observation at bog stations. Sov. Hydrol. Sel. Pap., 348–370. Beltman, B., van den Broek, T., Barendregt, A., Bootsma, M.C., Grootjans, A.P., 2001. Rehabilitation of acidified and eutrophied fens in the Netherlands: effects of hydrologic manipulation and liming. Ecol. Eng. 17, 21–31.

Brandyk, T., Szatylowicz, J., Oleszczuk, R., Gnatowski, T., 2003. Water-related physical attributes of organic soils. In: Parent, L.-E., Ilnicki, P. (Eds.), Organic Soils and Peat Material for Sustainable Agriculture. CRC Press, pp. 15–32. Bragg, O., Lindsay, R. (Eds.), 2003. Strategy and Action Plan for Mire and Peatland Conservation in Central Europe. Wetlands International, Wageningen, The Netherlands. Information Press Ltd, Oxford, UK. ˙ ´ J., Kozuchowski, ˙ Degirmendˇzic, K., Zmudzka, E., 2004. Changes of air temperature and precipitation in Poland in the period 1951–2000 and their relationship to atmospheric circulation. Int. J. Climatol. 24, 291–310. Eggelsmann, R., Heathwaite, A.L., Gross-Brauckmann, G., Kuster, E., Naucke, W., Schuch, M., et al., 1993. Physical processes and properties of mires. In: Heathwaite, A.L., Gottlich, K. (Eds.), Mires–processes, exploitation and conservation. John Willey & Sons Ltd, Chichester, pp. 171–262. Grootjans, A.P., ten Klooster, W.Ph., 1980. Changes of groundwater regime in wet meadows. Acta Bot. Neerl. 29, 541–554. Grootjans, A.P., van Diggelen, R., 1995. Assessing the restoration prospects of degraded fens. Restoration of temperate wetlands. In: Wheeler, B.D., Shaw, S.C., Fojt, W., Robertson, R.A. (Eds.), Restoration of Temperate Wetlands. John Willey & Sons Ltd, Chichester, pp. 73–89. Grootjans, A.P., Wołejko, L., 2007. Conservation of Wetlands in Polish Agricultural Landscapes. Nature Club Poland, Szczecin. ´ Grzyb, S., Pronczuk, J., 1994. Division and evaluation of meadow habitats and the assessment of their productive potential. In: Development of the grassland science in view of the present knowledge in its most important branches. Proceedings Polish Conference on Grasslands. Wydawnictwo SGGW, Warszawa, pp. 51–63. Huxman, T.E., Wilcox, B.P., Breshears, D.D., Scott, R.L., Snyder, K.A., Small, E.E., Hultine, K., Pockman, W.T., Jackson, R.B., 2005. Ecohydrological implications of woody plant encroachment. Ecology 86, 308–319. Ilnicki, P., Zeitz, J., 2003. Irreversible loss of organic soil function after reclamation. In: Parent, L.-E., Ilnicki, P. (Eds.), Organic Soils and Peat Material for Sustainable Agriculture. CRC Press, pp. 15–32. ´ Jabłonska, E., Pawlikowski, P., 2004. Betula humilis schrank in the Całowanie fen distribution dynamics, habitat changes and survival chances of the species in degraded peatland. Publication of the Polish Academy of Science, Lublin. Teka ´ Komisji Ochrony i Kształtowania Srodowiska Przyrodniczego I, 83–88. Jaksic, V., Kiely, G., Albertson, J., Oren, R., Katul, G., Leahy, P., et al., 2006. Net ecosystem exchange of grassland in contrasting wet and dry years. Agric. For. Meteorol. 139, 323–334. Jankowska-Huflejt, H., 2006. The function of permanent grasslands in water resources protection. J. Water Land Dev. 10, 55–65. Jansen, A.J.M., Grootjans, A.P., Jalink, M.H., 2000. Hydrology of Dutch CirsioMolinietum meadows: prospects for restoration. Appl. Veg. Sci. 3, 51–64. Joosten, H., Clark, D., 2002. Wise use of mires and peatlands. International Mire Conservation Group & International Peat Society, Saarijarvi, Finland. Jauhiainen, S., Laiho, R., Vasander, H., 2002. Ecological and vegetational changes in a restored bog and fen. Ann. Bot. Fenn. 39, 185–199. Kemmers, R.H., Van Delft, S.P.J., Jansen, P.C., 2003. Iron and sulphate as possible key factors in the restoration ecology of rich fens in discharge areas. Wetlands Ecol. Manage. 11, 367–381. Klimkowska, A., van Diggelen, R., Bakker, J.P., Grootjans, A.P., 2007a. Wet meadow restoration in Western Europe: a quantitative assessment of the effectiveness of several techniques. Biol. Cons. 140, 318–328. ˙ P., Brzezinska, ´ Klimkowska, A., Dzierza, K., Kotowski, W., van Diggelen, R., 2007b. Całowanie peatland. In: Grootjans, A.P., Wołejko, L. (Eds.), Conservation of Wetlands in Polish Agricultural Landscapes. Nature Club Poland, Szczecin, pp. 41–61. Klimkowska, A., 2008. Restoration of severely degraded fens: ecological feasibility, opportunities and constraints. PhD Thesis. University of Antwerp. Kotowski, W., Piórkowski, H., 2003. Poland. In: Bragg, O., Lindsay, R. (Eds.), Strategy and Action Plan for Mire and Peatlands Conservation in Central Europe Wetlands International. Information Press, Oxford, UK, pp. 49–53. ˙ ´ J., 2005. Contemporary changes of climate in Kozuchowski, K., Degirmendˇzic, Poland: trends and variation in thermal and solar conditions related to plant vegetation. Pol. J. Ecol. 53, 283–297. Lamers, L.P.M., Smolders, A.J.P., Roelofs, J.G.M., 2002. The restoration of fens in the Netherlands. Hydrobiologia 478, 107–130. ˛ Łabedzki, L., Roguski, W., Kasperska-Wołowicz, W., 2003. Ewapotranspiracja i ˛ dwuko´snej na glebie torfowo-murszowej w dolinie Noteci plonowanie łaki (Evapotranspiration and production on the double swath meadow on peat, in the ´ Notec River valley). Woda–Srodowisko–Obszary Wiejski 3 (9) Wydawnictwo IMUZ, Falenty (in Polish). De Mars, H., Wassen, M.J., Peeters, W.H.M., 1996. The effect of drainage and management on peat chemistry and nutrient deficiency in the former Jegrzniafloodplain (NE-Poland). Vegetatio 126, 59–72. Millennium Ecosystem Assessment, 2005. Ecosystems and Human Well-Being: Current State and Trends. Findings of the Condition and Trends Working Group. Island Press. Olszewski, K., 2003. Klimat mazowsza (Climat of Mazovia). In: Richling, A. (Ed.), Przyroda Mazowsza i jej antropogeniczne przekształcenia. Pułtusk (in Polish). ˛ O´swit, J., Dembek, W., 1984. Ekspertyza przyrodniczo-łakarska obiektu Całowanie–Podbiel (Production and natural values of the Całowanie–Podbiel peatland). In: IMUZ, Zakład Przyrodniczych Podstaw Melioracji, Falenty (in Polish). O´swit, J., Dembek, W., 2001. Geomorfologiczno-hydrologiczne uwarónkowania rozwoju mokradeł na przykładzie torfowiska Całowanie w dolinie s´ rodkowej Wisły (Geomorphological and hydrological conditions of the wet-

A. Klimkowska et al. / Landscape and Urban Planning 97 (2010) 249–257 lands development—an example of Calowanie fen in the middle Vistula River ´ valley). Woda–Srodowisko–Obszary Wiejski 1 (3) Wydawnictwo IMUZ, Falenty (in Polish). Podbielkowski, Z., 1960. Zarastanie dołów potorfowych (The development of Vegetation in Peat pits). Monographiae Botanicae 10, PWN, Warszawa (in Polish). Pribar, K., Ondok, J.P., 1980. The daily and seasonal course of evapotranspiration from a Central European sedge-grass marsh. J. Ecol. 68, 547–559. Reynolds, E.R.C., Thompson, F.B., 1988. Forests, Climate, and Hydrology. The United Nations University. Kefford Press, Singapore. Richert, M., Dietrich, O., Koppisch, D., Roth, S., 2000. The influence of rewetting on vegetation development and decomposition in a degraded fen. Restor. Ecol. 8, 186–195. Rudnicka, W., 1961. Dokumentacja geologiczna torfowiska Całowanie (Geological documentation of Calowanie Fen). Uniwersytet Warszawski, Warszawa (in Polish). ˛ Ryszkowski, L., Kedziora, A., 1987. Impact of agricultural landscape structure on energy flow and water cycling. Landscape Ecol. 1, 85–94. Schild, R., Tobolski, K., Kubiak-Martens, L., Pazdur, M.F., Pazdur, A., Vogel, J.C., et al., 1999. Stratigraphy, palaeoecology and radiochronology of the site of Całowanie. Folia Quaternaria 70, 239–268. Stephanson, N.L., 1998. Actual evapotranspiration and deficit: biologically meaningful correlates of vegetation distribution across spatial scales. J. Biogeogr. 25, 855–870. ´ Swiatek, D., Verhoeven, R., Chormanski, J., Okruszko, T., Ignar, S., Banasiak, R., 2008. Determination of influence of vegetation on the friction factors of the Biebrza River. Electron. J. Pol. Agric. Univ. 11, 05. Tiemeyer, B., Lennartz, B., Vegelin, K., 2006. Hydrological modeling of a re-wetted peatland on the basis of a limited dataset for water management. J. Hydrol. 325, 376–389. Timmermann, T., Margoczi, K., Gabor, T., Vegelin, K., 2006. Restoration of peat forming vegetation by rewetting species-poor fen grasslands. Appl. Veg. Sci. 9, 241–250. Trepel, M., Kluge, W., 2002. Ecohydrological characteristics of a degraded valley peatland in Northern Germany for use in restoration. J. Nat. Conservat. 10, 155–169. van der Salm, C., van der Gon, H.D., Wieggers, R., Bleeker, A., van den Toorn, A., 2006. The effect of afforestation on water recharge and nitrogen leaching in The Netherlands. Forest Ecol. Manage. 221, 170–182. van Diggelen, R., Grootjans, A.P., Kemmers, R.H., Kooijman, A.M., Succow, M., de Vries, N.P.J., van Wirdum, G., 1991. Hydro-ecological analysis of the fen system Lieper Posse, eastern Germany. J. Veg. Sci. 2, 465–476.

257

van Diggelen, R., Grootjans, A.P., Burkunk, R., 1994. Assessing restoration prospects of disturbed brook valley: the gorecht area, The Netherlands. Restor. Ecol. 2, 87–96. van Diggelen, R., Molenaar, W.J., Kooijman, A.M., 1996. Vegetation succession in a floating mire in relation to management and hydrology. J. Veg. Sci. 7, 809– 820. van Diggelen, R., Middleton, B., Bakker, J., Grootjans, A.P., Wassen, M., 2006. Fens and floodplains of the temperate zone: present status, threats, conservation and restoration. Appl. Veg. Sci. 9, 157–162. Vertessy, R.A., 2001. Impacts of plantation forestry on catchment runoff. In: Nambiar, E.K.S., Brown, A.G. (Eds.), Plantations, Farm Forestry and Water: Proceedings of a national workshop 20–21 July 2000, pp. 9–19, RIRDC Publication No. 01/20. Wassen, M.J., Barendregt, A., Palczynski, A., de Smidt, J.T., De Mars, H., 1990. The relationship between fen vegetation gradients, groundwater flow and flooding in an undrained valley mire at Biebrza, Poland. J. Ecol. 78, 1106–1122. Wassen, M.J., van Diggelen, R., Wolejko, L., Verhoeven, J.T.A., 1996. A comparison of fens in natural and artificial landscapes. Vegetatio 126, 5–26. Wassen, M.J., Olde Venterink, H., 2006. Comparison of nitrogen and phosphorus fluxes in some European fens and floodplains. Appl. Veg. Sci. 9, 213–222. Wassen, M.J., Okruszko, T., Kardel, I., Chormanski, J., Swiatek, D., Mioduszewski, W., Bleuten, W., Querner, E.P., El Kahloun, M., Batelaan, O., Meire, P., 2006. Ecohydrological functioning of the Biebrza wetlands: lessons for the conservation and restoration of deteriorated wetlands. In: Bobbink, R., Beltman, B., Verhoeven, J.T.A., Whigham, D.F. (Eds.), Wetlands: Functioning, Biodiversity Conservation, and Restoration. Springer-Verlag, Berlin, Heidelberg, pp. 285–310, Ecological Studies, 191. Wierda, A., Fresco, L.F.M., Grootjans, A.P., van Diggelen, R., 1997. Numerical assessment of plant species as indicators of the groundwater regime. J. Veg. Sci. 8, 707–716. Zedler, J.B., 2000. Progress in wetlands restoration ecology. Trends Ecol. Evol. 15, 402–407. Zedler, J.B., Kercher, S., 2005. Wetland resources: status, trends, ecosystem services, and restorability. Annu. Rev. Environ. Resour. 30, 39–74. ˙ ˛ Zurek, S., 1990. Zwiazek procesu zatorfienia z elementami s´ rodowiska przyrodniczego wschodniej Polski (A relation between peat forming and the natural environment in East Poland). Roczniki Nauk Rolniczych, Monografie 220, PWN, Warszawa (in Polish).