Sphagnum bogs… …would they be as acid by any other name?

1. Sphagnum bogs……would they be as acid by any other name?

2. Louise Kulzer Water quality specialist, Aquatic ecologist King County Department of Natural Resources (Scott Luchessa, Fred Weinmann, Sarah Cooke collaborators)

3. Why we’re here... “In the end, we will conserve only what we love, we will love only what we understand, and we will understand only what we are taught.” -- Baba Dioum, Senegal

4. Goals • To understand the unique characteristics of sphagnum bogs • To understand how human influences can adversely impact sphagnum bogs • To see a peat system first-hand

5. What you’ll learn about... • Where & how bogs are formed • How sphagnum moss creates it’s own niche • Physical & chemical gradients in wetlands & where bogs fit in • Plant & animal communities in bogs • How human activities can disrupt bogs

6. Definitions (after Bridgham, 1998) Peatland is a generic term applied to wetlands in which the rate of accumulation of organic matter exceeds the rate of decomposition, and where at least 1 foot ( 30 - 40 cm) of peat has accumulated (Glaser, 1987) (Mire is the European name for peatlands) Two basic divisions in peatlands: bogs -- acidic peatlands, Sphagnum moss forms dense mat fens-- depends on classification-- usually more sedges, less acidic

7. Definitions, cont’dOther peatland types muskeg-- northern peatlands covered with stunted black spruce (Crum, 1992) rooted in Sphagnum moors-- in Britain, bleak, uncultivated land, not necessarily peaty. “High-moor” is characterized by calcium poor substrates and Sphagnum mosses. heath--in Britain, areas of infertile, often peaty soils supporting shrubby vegetation. Typically over-grazed historically. carr-- a peat system, usually not Sphagnum-dominated, supporting deciduous trees

8. Types of bogs terrestrialization • lake-fill or kettle-hole bogs • flat basin • plateau or raised bogs • Blanket bogs • flat valley • slope bogs carpets, lawns (use differs with authors) open hummock/hollow, usually w/ shrubs forested paludification

9. Bogs form in specific environmental situations Precipitation exceeds evaporation

10. Bogs form in specific environmental situations • Drainage is poor (plateaus, drainage divides) • Poor soils, often glaciated • Kettle holes • Cool temperatures • Oceanic influence common-- rainfall higher in Na & Cl • Northern latitudes • in lakes, protected from wind, upstream flowpaths

11. Distribution of bogs

12. Sequence /age of peat profile Puget Sound region • Often underlain by blue clay • sedge peat • pumicite layer (laid down 6,700 yr b.p. (151 obs.)) • sphagnum peat • 11,900 yr. b.p. average for beginning of peat accumulation • 41 years/ inch of peat accumulation (151 obs, Puget Sound lowlands) Other NW bogs: 49 years / inch (55 obs in NE Wa, Idaho, BC) Northern Minnesota-- 4,000 yr. BP (mid-holocene)

13. Characteristics of sphagnum bogs • form mats which are at least somewhat buoyant • mats often form hummocks & hollows, support a unique assemblage of plants • water acidic • bacterial communities severely depressed, but aquatic fungi thrive • lack of dissolved oxygen, minerals and nutrients in water • typically have a moat or “lagg” at periphery

14. Gradients operating in peatlands • source of water rain runoff  groundwater • water mobility stagnant  flowing • water chemistry (pH, cations, anions, nutrients) low  high • water levels stable  fluctuating

15. More gradients • sunlight shade • summer winter • hummock hollow • mat lagg or moat

16. rich fen poor fen rheophilous geogenous (minerotrophic) Vegetation community gradients responding to abiotic gradients, made up of many attributes. Different investigators draw the line between the names (fens vs. bogs) in different ways. Bridgham, et al., 1996, call for new paradigm (“Multiple limiting gradients in peatlands, a call for a new paradigm.” Wetlands, Vol. 16, No. 1, March 1996, pp. 45-65) bog ombrophilous ombrogenous (ombrotrophic) What’s in a name?

17. What’s in a name? Makes sense to use a “weight of evidence” approach in referring to peatlands as either bogs or fens rather than a single indicator. Vegetation, esp. Sphagnum, should be one of the indicators. Variable, especially across latitudinal and altitudinal gradients Sphagnum BOG FEN

18. water source mobility chemistry pH cations anions nutrients water level bogs fens rainwater surface & groundwater stagnant flowing acid neutral or basic scarce abundant Cl dominant CO3, HCO3 dominant low high stable stable or fluctuating Generally

19. Bottom line: Sphagnum bogs are isolated from the influences of groundwater &/or surface water runoff in some way • topography (small watershed, flat area) • impermeable layers • blue clay • decomposed peat itself • raised character of hummocks or plateau • moat or lagg

20. Sphagnum moss • Indeterminate growth • upper portion actively grows,bottom portion sloughs away, may sink to bottom or be suspended • dozens of species, w/ own growth habits, tolerances for pH, light, wetness • leaves thin, only 1 cell thick • cell walls w/ perforations, high concentrations of polyuronic acid, an active cation exchanger • high water-holding capacity (15-23X dry weight)

21. Sphagnum ecology • Numerous species, 61 in European mires • wide range of pH tolerances • some species are specialists, some generalists • Coastal BC-- 6 species groups • degree of shading • height above water table • surface water chemistry • No definitive local taxonomy done for WA, OR

22. 2’ Zone 1 interstitial spaces aerated Zone 2 interstitial spaces saturated, water oxygenated Zone 3 interstitial spaces saturated, water anoxic Profile through a sphagnum hummock acrotelm catotelm

23. Dissolved oxygen in bogsincreasing depth within mat

24. pH of natural waters Typical wetland Small stream 1 2 3 4 5 6 7 8 9 10 11 12 13 14 acidic pH (log scale) basic (data from the Puget Sound area) Rain L. Washington Bog

25. Sources of acidity in bogs • decomposition of peat in the acrotelm yields organic acids • humic acids • fulvic acids • redox reaction of sulfur compounds yields acids • Cation exchange by sphagnum -- H+

26. Bog/fen gradient

27. Cation exchange Ca++ Na+ H+ Mg++ Mg++ K+ Ca++ 2 H+ Na+ Polyuronic acid on sides of cell wall

28. Buffering systems in waters Atmosphere: CO2 CO2 + H2O = H2CO3 H2CO3  H++ HCO3- 2H++ CO3-- organicCO2HCO3-HCO3- acids H2CO3 bicarbonate carbonic acid CO3-- carbonate pH 3 4 5 6 7 8 Typ. wetlands bogs

29. Carbonate - bicarbonate buffering system

30. Cations Solution Na+ K+ Ca++ Mg++ organic acid+ pH 6 8 Salts NaHCO3 K2CO3 CaCO3 MgCO3 organic salt 1 0 Buffers in natural waters, cont’d HCO3- H+ H+ CO3-- HCO3- H+ H+ H+ H+ CO3--

31. Chemistry of waters: cationsdata from Puget Sound area (typical)hardness (Ca + Mg)alkalinity (... mg/L CaCO3) 1 10 20 30 40 50 60 70 80 90 Urban runoff Typical wetlands Bogs, sm. streams groundwater L. Wa. Tea-stained lake

32. Chemistry of waters: nutrientsdata from Puget Sound areaTotal phosphorus concentrations bog rain Typ. wetland Urban runoff/groundwater .01 * 0.05 0.1 0.5 1.0 5.0 10 Total Phosphorus (mg/L) * L.Wa

33. Chemistry of waters: nutrientsdata from Puget Sound areaNitrogen(NO3) mg/L Nitrogen concentrations Groundwater Urban runoff .001 .005 .01 .05 .1 * .5 1 L. Washington Typical wetland bog Rain

34. Inlet stream Ca++2.0 Mg++ 0.9 Na+ 2.0 K+ 0.4 Units: mg/L pH 6.3 lagg Sphagum Mat 1.9 0.7 0.8 0.3 1.8 0.6 0.6 0.5 5.6 4.2 Cations in surface watersELS21, April 26, 1993

35. groundwater* Ca++4.7 Mg++8.4 Na+0.9 K+3.0 Alkalinity 30.0 Units: mg/L pH 6.2 * Avg, 60 m from bog sphagnum lagg mat 4.9 0.4 2.1 0.2 2.5 0.8 0.6 1.3 16 <1 6.9 4.2 Cations in surface & groundwaterLCR16, 1998-9

36. Mauncha diagram o H+ K+ HCO3- Na+ Cl-Ca++ SO4=Mg++

37. Microbial characteristics Bog water Moat area heterotrophic A 85 11,000 plate count B 119 13,700 yeast A 400 6,800 plate count B 310 5,800 filamentous A 20 3,500 mold B 18 2,800 Units: CFU/ ml

38. Hypothetical plant gradients • Emergents (sedges, skunk cabbage, etc.) • sedge peat • sphagnum moss • lawns • hummocks & hollows • ericacious shrubs • stunted trees • closed canopy forest over peat

39. Gradients in herbaceous species:Minnesota peatlands (Glasser, 1987) Bogs Carex oligosperma Eriophorum spissum Poor fens Rhynchospora alba Carex limosa Rich fens Carex chordorrhiza, C. lasiocarpa

40. Common bog plants (Based on fall 1998 survey, 30 Puget Sound bogs) 30 Ledum groenlandicum (Labrador tea) 25 Tsuga heterophylla (hemlock) 20 Kalmia microphylla (bog laurel) 17 Spirea douglasii 17 Vaccinium oxycoccus (cranberry) 15 Thuja plicata (w. red cedar) Pink font = family Ericaceae

41. Other common bog plants Drosera rotundifolia (sundew) Cladium (reindeer lichen) Rhynchospora alba (beakrush) stunted Sitka spruce, shorepine, white pine crabapple, cascara, willow, birch blueberry, huckleberry Eriophorum (cottongrass), Menyanthes (bogbean) Scirpus atrocinctus (= cyperinus) skunk cabbage

42. Uncommon bog plants Carex pauciflora (few-flowered sedge) Olympic peninsula Myrica gale (sweet gale) Rhododendron macrophyllum Gentianan sp. (bog gentian) Habenaria dilatata (bog orchid) British Columbia Andromeda sp. (bog rosemary) Rubus sp. (cloudberry)

43. Unique bog beetles--WA state sensitive status

44. Effects of human activity

45. Uses of sphagnum • soil amendment • fuel source, ancient times to present • acid-loving crops • cranberries • blueberries • truck farms (Ravenna P-patch) • paleo-botanical record • historical record • absorbent material -- bandages WW1, diapers

46. Historical changes in sphagnum acreage -- King County, WA 24 King County Bogs, 1930s to 1990 Sphagnum acres 1930 1980 1990 Total 458 140 132  71% reduction in acreage 1930 acres from Rigg, Peat Resources of Washington 1980, 90 acres estimated from from air photos

47. Urbanization of watershed • volume of annual runoff increased ~ 40% • increases winter high water level • increases water level fluctuation • concentration of cations, nutrients greatly increases ( changes buffer equilibrium) • bacterial concentration increase • physical disturbance increases (pets, people)

48. Responses to urban runoff • Binding of cations+ greatly increased, may use up exchange sites and kill moss • buffering system equilibrium disturbed • WLF causes • increased depth of D.O., increased area of acrotelm, more decomposition of mat • higher winter, lower summer water levels • increased bacteria, more decomposition • higher nutrients favor typical emergents

49. Recent changes in sphagnum acreage -- King County

50. Recent changes in sphagnum acreage -- King County Of the 50 remaining bogs in King Co. WA most show damage • draining • dirt paths, roads • cuts for ROW, ditches • invasion by non-acid loving plants (more overland runoff) • erosion of mat (increased O2, WLF) • trampling