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

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

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

Goals C CTo understand the unique characteristics of sphagnum bogs C CTo understand how human influences can adversely impact sphagnum bogs C CTo see a peat system first-hand

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

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 ( 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

Other peatland types Definitions, cont’d Other 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

Types of bogs 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 terrestrialization paludification

Bogs form in specific environmental situations Bogs form in specific environmental situations Precipitation exceeds evaporation

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

Distribution of bogs

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)

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

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

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

What’s in a name? 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 ) bogombrophilousombrogenous (ombrotrophic) (ombrotrophic)

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

Generally water source mobility chemistry pH cations anions nutrients water level bogsfens bogsfens rainwater surface & groundwater stagnant flowing acid neutral or basic scarce abundant Cl dominant CO 3, HCO 3 dominant low high stable stable or fluctuating

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

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)

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

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

Dissolved oxygen in bogs increasing depth within mat

pH of natural waters Small stream Rain Bog L. Washington Typical wetland acidicpH (log scale) basic (data from the Puget Sound area)

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 +

Bog/fen gradient

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

Buffering systems in waters Atmosphere: CO 2 CO 2 + H 2 O = H 2 CO 3 H 2 CO 3  H + + HCO 3 -  2H + + CO 3 -- organic CO 2 HCO 3 - HCO 3 - acids H 2 CO 3 bicarbonate carbonic acid CO 3 -- carbonate pH Typ. wetlands bogs

Carbonate - bicarbonate buffering system

Buffers in natural waters, cont’d Cations Solution Na+ K+ Ca++ Mg++ organic acid+ pH 6 8 Salts NaHCO 3 K 2 CO 3 CaCO 3 MgCO 3 organic salt 1 0 HCO 3 - H + H + CO 3 -- HCO 3 - H + H + H + H + CO 3 --

Chemistry of waters: cations data from Puget Sound area (typical) hardness (Ca + Mg) alkalinity (... mg/L CaCO 3 ) Urban runoff Typical wetlands Tea-stained lake L. Wa. groundwater Bogs, sm. streams

Chemistry of waters: nutrients data from Puget Sound area Chemistry of waters: nutrients data from Puget Sound area Total phosphorus concentrations.01 * Total Phosphorus (mg/L) Urban runoff/groundwater Typ. wetland rain L.Wa * bog

*.5 1 Chemistry of waters: nutrients data from Puget Sound area Nitrogen( NO 3 ) mg/L Urban runoff Rain L. Washington Typical wetland bog Nitrogen concentrations Groundwater

Cations in surface waters ELS21, April 26, 1993 Inlet stream Ca Mg++0.9 Na+2.0 K+0.4 Units: mg/L pH6.3 lagg Sphagum Mat

Cations in surface & groundwater LCR16, groundwater* Ca Mg Na K Alkalinity 30.0 Units: mg/L pH 6.2 * Avg, 60 m from bog sphagnum lagg mat <

o Mauncha diagram H+ K+ H+ K+ HCO 3 - Na+ HCO 3 - Na+ Cl - Ca++ Cl - Ca++ SO 4 = Mg++ SO 4 = Mg++

Microbial characteristics Bog water Moat area heterotrophicA 85 11,000 plate countB ,700 yeastA 400 6,800 plate count B 3105,800 filamentous A 203,500 moldB 182,800 Units: CFU/ ml

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

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

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

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

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)

Unique bog beetles-- WA state sensitive status

Effects of human activity

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

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

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)

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

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 O 2, WLF) –trampling

Recent changes in sphagnum acreage -- King County Impacts of recent drainage, LCR14   hemlock growth taller near cut face of bog   # years of accelerated growth increase closer to the cut face   height of Ledum increases, little Kalmia near cut face   Dry hummocks, no bog beetles near cut face

The case of LCR air photo

1995 air photo Drainage from cut face

LCR14

King County Surface Water Design Manual Sphagnum bog protection menu applied throughout watershed Goals: reduce TP by 50% reduce N by 40% alkalinity < 10 mg/L pH < 6 3-facility WQ treatment train facilities which contribute organic acids ALSO: match pre-developed volumes

Consequences of accelerated peat system decay Consequences of accelerated peat system decay  Excess nutrients to downstream lakes Release of greenhouse gases (methane) Loss of unique wetland type Loss of unique habitat for plants, invertebrates Loss of hydrological “sponge” depresses summer low flows, increases winter high flows Loss of paleobotanical, geological records

Are we doing enough? Stormwater treatment facilities remove about half of increased cations, nutrients Construction impacts Logging & agricultural impacts Air pollution, urban climate modification Extraction (sphagnum peat use by gardeners widespread) Roads can block drainage recharge Trampling problem “walking on meringue”

So what to do? Keep entire catchment forested-- no logging Keep roads out of catchment Limit any construction/ land disturbance to dry season No cement use in catchment Don’t give mining permits, stop using peat Construct modest, low-impact trails Show people! You can’t long protect what people don’t value.

LCR16 from moat looking to bog mat

gift of the glaciers gift of the glaciers