1. 1 Hydrogeomorphic Pothole Types in Agricultural Landscapes of East- Brandenburg Centre for Agricultural Landscape and Land Use Research (ZALF) Thomas Kalettka ZALF, Institute of Hydrology, tkalettka@zalf.de

2. 2 Agricultural landscape with potholes in spring

3. 3 Soll (German); pothole, kettle hole (English) = glacially shaped isolated depression within the sink of an internal catchment in the young moraine landscape standing water or wetland respectively - water area </= 1 ha - - depression area </= 3 ha - hydrogeomorphic (HGM) type (Brinson 1993): isolated depression with vertical water fluctuation

4. 4

5. 5 Water regime of potholes in agricultural landscapes of East-Brandenburg Mapping of wetness 1993-2002

6. 6 Morphological parameters of a pothole Cross section Top view EB = Edge border TSB = Top shore border BSB = Bottom shore border HwL = High water line MwL = Middel water line

7. 7 Classification of hydrogeomorphic variables of potholes VariablesClasses 12345 catchment area [ha] 1.0 very small 3.2 small 10.0 middle 31.6 big > 31.6 very big area ratio 3 very small 10 small 32 middle 100 big > 10 very big catchment reliefflatslightly rollingmiddle rollingstrong rollinghilly pothole area [ha] 0.03 very small 0.10 small 0.32 middle 1.00 big > 1.00 very big maxiumum depth bottom shore depth [m] 1.0 very wadeable 1.6 wadeable 2.5 very shallow 4.0 shallow > 4.0 deep shore slope [%] 10 flat 20 sloping 30 very sloping 40 steep > 40 very steep shore width [m] 4 very narrow 6 narrow 10 middle 16 wide > 16 very wide length/width at top shoreline 1.5 roundish 2.5 oval > 2.5 stretched water regimenever watertemporary (episodic) seasonally (periodic) semiper- manent permanent shore overflow tendency notpartlycompletely

8. 8 Factor analysis of hydrogeomorphic variables of potholes (n=144) VariablesCatchment and Pothole Area Factor Overflow Factor Relief and Shape Factor water regime 0.86 0.13-0.12 shore overflow tendency -0.06 0.85 0.07 catchment area 0.65 0.19-0.27 catchment relief 0.18 -0.05 -0.76 pothole area 0.81 0.24-0.24 maximum depth 0.75 -0.430.07 max. depth – bottom shore depth 0.81 -0.140.03 length/width 0.030.08 -0.77 shore slope -0.16 -0.86 0.11 explained variance (value)3.101.801.36 part of total variance %342015 extraction: main components; factor rotation: varimax; results: factor loadings of variables, marked loadings 0,65

9. 9 Cluster analysis for derivation of hydrogeomorphic pothole types Example: Cluster of shallow potholes (n=95, mean values, K-Means-Cluster analysis) WR = Water regime; SBT = Shore overflow tendency, CA = Catchment area; PA = Pothole area at top shore; SS = Shore slope

10. 10 potholes (isolated depressions with vertical water fluctuation) 2. Water bearing Types (permanent to temporary flooded, organic and mineral sediments) WR: 2-5 1. Fen-Type (growing fen) WR: 1-2 2.1 Storage-Type (permanent shore) WR: 2-5 2.2 Shore Overflow-Type (permanent shore) WR: 2-5 2.3 Puddle Type (nonpermanent shore) WR: 2 2.1.1 Big Deep WR: 4-5 2.1.2. Big Shallow WR: 3-5 2.1.3 Small Shallow WR: 2-3 2.1.4 Small Wadeable WR: 2-3 2.2.1a Big Shallow WR: 3-5 2.2.2 Big Wadeable WR: 3-5 2.2.3 Small Shallow WR: 2-4 2.2.4 Small Wadeable WR: 2-3 2.2.1b with peaty island WR: 3-5 WR = Water Regime 1: never, 2: episodic (temporary, 3: periodic (seasonal), 4: semipermanent, 5: permanent Hydrogeomorphic types of potholes in agricultural landscapes

11. 11 Short form of the determination key for water bearing hydrogeomorphic pothole types 1.2.3.4. Pothole TypeMDPermanent shore SSOTPACAWRCR never <3 Puddle type1---112- Small wadeable shore overflow type 1-2X (3-) 5 1-3 2-3 (-4) - Big wadwable shore overflow type 1-2X (-3) 3(3-) 4-5 3-4 (-5) - Small wadeable storage type 1-2X3-4 (-5) 11-3 2-3- Small shallow overflow type 3-4X1-35 (2-) 3-4 - Big shallow overflow type3-4X1-3(3-) 5 3-5(2-)3-4, 2 only if PA 1-2 3-5- Small shallow stoirage type 3-4X3-511-31-2(-3), 3 only if PA 1-2 2-3(-4)- Big shallow storage type3-4X3-51 3-43-4(-5)- Big deep storage type5X1-513-53-43-5X MD = max. depth; SS = Shore slope; OT = overflow tendency; PA = pothole area; CA = catchment area; WR = water regime; CR = catchment relief

12. 12 HGM-type: Big deep storage type Dom. veg.: Edge type with shore woods (Sambucus nigra, Salix cinerea)

13. 13 HGM-type:Small shallow shore overflow type Dom. vegetation: Edge type with Phalaris-reed (P. arundinacea)

14. 14 HGM-type:Big shallow shore overflow type Dom. veg.: Full reed type with sedges (C. elata) and reed (P. australis)

15. 15 HGM-type: Big shallow shore overflow type + peaty island Dominant vegetation: Wood type with Betula stand (B. pubescens)

16. 16 HGM-type: Big shallow storage type Dominant vegetation: Full reed type (Phragmites australis)

17. 17 HGM-type: Small wadeable overflow type Dominant vegetation: Full reed type (Phalaris arundinacea)

18. 18 HGM-type: Puddle typeDominant vegetation: Annual herbs

19. 19 Example of a target image for a hydrogeomorphic pothole type small wadeable storage type Morphology max. depth < 1. 6 m, shore slope 20-40 % Water Regime temporary (- seasonal), no shore overflow Water Quality high eutroph (-polytroph) Dominant Vegetation (edge type), full reed type, wood type Aquatic Vegetation usually no hydrophytes Amphibic Vegetation dominance of large area reeds (tall and little reeds) additionally mudflat herbs and Salix cinerea stands Terrestrial Vegetation perennial herbs, grasland, low share of nitrophile and ruderal species woods of low wet soils (Quercus, Ulmus, Tilia)

20. 20 Sink-FunktionsMGTSGFSKFSKSSGFAGSAKFAKSAP storage for surface water 0xxx xx xxX permanent water regime 0xxxxx00 000 temporary water regime xxxxxxxxx xx xxx deep water body in whole year 0xxxxxx0 xx00 accumulation of peat (growing fen) xxx0000xxx000 storage for relict peat xxxxx xx xxx moderate pollution by nutrients (water quality) xxx xxxx xx0 quick mineralisation by wet-dry-cycle 0xxxxxx xx xxx Potential abiotic functions for HGM pothole types in the agricultural landscape 0 – nox - lowxx – moderatexxx - high other functions: source function (groundwater recharge, gas emission) microclimat. function (slowing down of wind, local humidity)

21. 21 0 – nox - lowxx – moderatexxx - high Other functions: Hideaway for endangered species of open landscape Stepping stone in the biotope integrated system Potential habitat functions for vegetation of HGM pothole types in the agricultural landscape Functions forFBDSBSSSSSSWSBSOBWOSSOSWOP high biodiversity xxxxx xxxxxxxx x hydrophytes 0xxx xxx x xx tall reeds xxx xxxx xx 0 small reeds 0xxxxxxxxxxxxxxxxxxx sedges xxxx x0 xxx00 annual herbs 0xxxxxxxxxxxxxxxx swamp/fen woods xxxxx xxxxx0 woods of low wet shores xxx xx 00000

22. 22 slightly to middle rolling ground moraine 78 % small, 36 % wadeable, 52 % shore overflow hilly rolling ground moraine 88 % big, 6 % wadeable, 38 % shore overflow Distribution of hydrogeomorphic pothole types depending on landscape relief