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...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 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

What you’ll learn about...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 Definitions (after Bridgham, (after Bridgham, 1998)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

Definitions, cont’d

Other peatland typesOther peatland typesmuskeg-- 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 bogsTypes 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 Bogs form in specific environmental situations environmental situations

Precipitation exceeds evaporation

Bogs form in specific Bogs form in specific environmental situationsenvironmental 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 bogsDistribution of bogs

Sequence /age of peat Sequence /age of peat profileprofilePuget 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 Characteristics of sphagnum bogsbogs

• 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 Gradients operating in peatlandspeatlands

• source of water

rain runoff groundwater

• water mobility

stagnant flowing

• water chemistry (pH, cations, anions, nutrients)

low high

• water levels

stable fluctuating

More gradients More gradients

• sunlight shade

• summer winter

• hummock hollow

• mat lagg or moat

What’s in a name?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. 45-65)

bogbog

ombrophilousombrophilous

ombrogenousombrogenous (ombrotrophi(ombrotrophic)c)

What’s in a name?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

GenerallyGenerally

water source

mobility

chemistry

pH

cations

anions

nutrients

water level

bogsbogs fens fens

rainwater surface & groundwater

stagnant flowing

acid neutral or basic

scarce abundant

Cl dominant CO3, HCO3 dominant

low high

stable stable or fluctuating

Bottom line: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

SphagnumSphagnum moss 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 ecologySphagnum 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 Profile through a sphagnum hummockhummock

2’2’

Zone 1 interstitial spaces aerated

Zone 2 interstitial spaces saturated, water oxygenated

Zone 3 interstitial spaces saturated, water anoxic

acrotelm

catotelm

Dissolved oxygen in bogsDissolved oxygen in bogsincreasing depth within matincreasing depth within mat

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

4" 12" 20"

site1site2site3site4

Little Lake, Snohomish county, WA

depth from surface

DOmg/ L

/ L

pH of natural waterspH of natural waters

Small streamSmall stream

RainRain

BogBog

L. WashingtonL. Washington

Typical wetlandTypical wetland

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)

Sources of acidity in bogsSources 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 gradientBog/fen gradient

Bog Fen

Mitch &Grosselink, 1993

Moss (Sphagnum) -dominated

Grass & sedgedominated

Gignac& Vitt,1990

Sphagnum-dominated

Mod. richfens

Rich fens

Sjors,1950

Moss Extremepoorfen

TransPoorfen

Intermedrich fen

Transrichfen

Extremerich fen

Weber1909

Hochmoore Ubergangs-moore

Niedermoore

Cation exchangeCation exchangeCa++ Na+ H+ Mg++

Mg++ K+

Ca++

2 H+

Na+

Polyuronic acid on sides of cell wall

Buffering systems in Buffering systems in waterswaters

Atmosphere: CO2

CO2 + H2O = H2CO3

H2CO3 H++ HCO3- 2H++ CO3

--

organic CO2 HCO3

- HCO3-

acids H2CO3 bicarbonate

carbonic acid CO3--

carbonatepH 3 4 5 6 7 8

Typ. wetlandsbogs

Carbonate - bicarbonate Carbonate - bicarbonate buffering systembuffering system

Buffers in natural waters, Buffers in natural waters, cont’dcont’d

Cations Solution

Na+

K+

Ca++

Mg++

organic acid+

pH 6 8

Salts

NaHCO3

K2CO3

CaCO3

MgCO3

organic salt

1 0

HCO3- H+

H+ CO3--

HCO3- H+

H+ H+

H+ CO3--

Chemistry of waters: Chemistry of waters: cationscationsdata from Puget Sound area (typical)data from Puget Sound area (typical)

hardness (Ca + Mg)hardness (Ca + Mg)

alkalinity (... mg/L alkalinity (... mg/L CaCOCaCO33))

1 10 20 30 40 50 60 70 80 901 10 20 30 40 50 60 70 80 90Urban runoff

Typical wetlands

Tea-stained lake

L. Wa.

groundwaterBogs, sm. streams

Chemistry of waters: nutrientsChemistry of waters: nutrientsdata from Puget Sound areadata from Puget Sound area

Total phosphorus concentrations

.01 .01 * * 0.05 0.1 0.5 1.0 5.0 10 0.05 0.1 0.5 1.0 5.0 10 Total Phosphorus (mg/L)Total Phosphorus (mg/L)

Urban runoff/groundwater Typ. wetland

rain

L.Wa

*

bog

.001 .005 .01 .05 .1 * .5 1

Chemistry of waters: nutrientsChemistry of waters: nutrientsdata from Puget Sound areadata from Puget Sound area

Nitrogen(Nitrogen(NONO33)) mg/L mg/L

Urban runoff

Rain

L. WashingtonTypical wetland

bog

Nitrogen concentrations

Groundwater

Cations in surface watersCations in surface watersELS21, April 26, 1993ELS21, April 26, 1993

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 0.70.7

0.8 0.30.3

1.8 0.60.6

0.6 0.5

5.6 4.24.2

Cations in surface & Cations in surface & groundwatergroundwater LCR16, 1998-9LCR16, 1998-9

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

Mauncha diagramMauncha diagram

H+H+ K+ K+

HCOHCO33-- Na+ Na+

ClCl-- Ca++Ca++

SOSO44== Mg++Mg++

Microbial characteristicsMicrobial characteristicsBog water Moat area

heterotrophic A 85 11,000

plate countB 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

Hypothetical plant Hypothetical plant gradientsgradients• Emergents (sedges, skunk cabbage,

etc.)

• sedge peat

• sphagnum moss

– lawns

– hummocks & hollows

– ericacious shrubs

– stunted trees

• closed canopy forest over peat

Gradients in herbaceous Gradients in herbaceous species:species:Minnesota peatlands (Glasser, 1987)Minnesota peatlands (Glasser, 1987)BogsBogs

Carex oligospermaCarex oligosperma

Eriophorum spissumEriophorum spissum

Poor fensPoor fens

Rhynchospora albaRhynchospora alba

Carex limosaCarex limosa

Rich fensRich fens

Carex chordorrhiza, C. lasiocarpaCarex chordorrhiza, C. lasiocarpa

Common bog plantsCommon bog plants(Based on fall 1998 survey, 30 Puget Sound

bogs)

30 Ledum groenlandicum Ledum groenlandicum (Labrador tea)(Labrador tea)

25 Tsuga heterophylla (hemlock)

20 Kalmia microphyllaKalmia microphylla (bog laurel) (bog laurel)

17 Spirea douglasii

17 Vaccinium oxycoccusVaccinium oxycoccus (cranberry) (cranberry)

15 Thuja plicata (w. red cedar)

Pink font = family EricaceaePink font = family Ericaceae

Other common bog plantsOther common bog plantsDrosera 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 plantsUncommon bog plantsCarex 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--Unique bog beetles--WA state sensitive statusWA state sensitive status

Effects of human activity Effects of human activity

Uses of sphagnumUses 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 Historical changes in sphagnum acreage -- King sphagnum acreage -- King County, WACounty, 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

Urbanization of watershed 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 runoffResponses 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 Recent changes in sphagnum acreage -- King sphagnum acreage -- King CountyCountyLoss of Sphagnum acreage in inventoried bogs since 1980

Sphagnum acresBog name 1980 1995 Impact

Mill Creek 18 12 0 Housing development,utility placement

LCR22 10 0 Housing developmentLCR25 2.1 0 Housing developmentJenkins Cr17 9 0 MiningHylebos Cr 34 1.4 0 Housing development

Total 34.5 0Loss of sphagnum communities in 5 out of 55 inventoriedwetlands having bog components in 1980 = 9%

Recent changes in Recent changes in sphagnum acreage -- King sphagnum acreage -- King CountyCountyOf the 50 remaining bogs in King Co. WA Of the 50 remaining bogs in King Co. WA most show damagemost show damage

– drainingdraining– dirt paths, roadsdirt paths, roads– cuts for ROW, ditchescuts for ROW, ditches– invasion by non-acid loving plantsinvasion by non-acid loving plants

(more overland runoff)(more overland runoff)– erosion of mat (increased Oerosion of mat (increased O22, WLF), WLF)– tramplingtrampling

Recent changes in Recent changes in sphagnum acreage -- King sphagnum acreage -- King CountyCounty

Impacts of recent drainage, LCR14Impacts 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 LCR14 The case of LCR14 1934 air photo1934 air photo

1995 air photo1995 air photo

Drainage from cut face

LCR14LCR14

T r e e g r o w t h v s d i s t a n c e

0

5

1015

20

25

8 16 23 152

D i s t a n c e ( m )

# r

i n

g s /

2 c

m # rings

King County Surface Water King County Surface Water Design ManualDesign 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 Consequences of accelerated peat system decaypeat 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?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?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 LCR16 from moat looking to bog matmat

gift of the gift of the glaciersglaciers