Matanuska-Susitna Wetland Mapping

Cook Inlet Wetlands

Mike Gracz
13 January, 2010

KETTLE  ECOSYSTEM Wetlands

DEM of Kettles east of Big Lake

A 2004 satellite image map showing Kettle wetlands and lakes southeast of Big Lake.

Kettle Ecosystem wetlands are peatlands occupying depressions created when pockets of underlying ice melted at the end of the last glacial advance (ice-block depressions). They have a wetland or stream connection to Cook Inlet, unlike Depression and Spring Fen ecosystem wetlands, which also formed in ice-block depressions. Depressions and Spring Fens are surrounded by uplands.

Photo of a Kettle near Blodgett Lake

A Kettle west of Blodgett Lake.

Table 1. Wetland Indicators in Kettle Ecosystem map components throughout the Cook Inlet Lowlands.

Map Component

Peat Depth (cm)

Water Table (cm)

Redox features (cm) Saturation (cm) pH Specific Conductance µS/cm Plant Prevalence Index

K1

        6.6 (34) 70.4 (34)  

K2

172(59)

6 (69)

  1 (35) 5.5(32) 82.1 (25) 1.59 (47)

K3

138 (82) 21 (87)   5.2 (30) 4.8 (30) 77.1 (21) 2.20 (72)

K4

104 (64) 32 (66) 36 (21) 25 (27) 5.2(13) 69.6 (10) 2.46 (57)

Explanation:

All data from wetlands throughout the Cook Inlet Lowlands, not just from the Matanuska-Susitna Valley. Headwater fens are realtively uncommon.

Numbers in paraentheses indicate number of samples.

Peat depth is a minimum, because some sites had thicker peat deposits than the length of the auger used (between 160 - 493 cm).

Water table depth is a one time measurement. At sites with seasonally variable water tables this measurement reflects both the conditions that year, and the time of year.

Redox features with deep depths typically indicate deeper peat deposits, which mask redox indicators so the depth corresponds to the peat thickness.

pH and specific conductance measured in surface water or a shallow pit with a YSI 63 meter calibrated each sample.

Plant Prevalence Index calculated based on Alaska indicator status downloaded from the USDA PLANTS database, which may use different values than the 1988 list.


 

Table 2. Common soils and plant communities found in Kettle Ecosystem wetlands.

Map Component

COMMON SOILS COMMON PLANT COMMUNITIES

K2

STARICHKOF

DOROSHIN

HISTOSOLS

Trichophorum caespitosum - Trichophorum alpinum

Trichophorum caespitosum - Carex pauciflora

Trichophorum caespitosum - Betula nana

Sphagnum spp. - Carex chordorrhiza

K3

STARICHKOF

DOROSHIN

HISTOSOLS

Sphagnum spp. - Ericaceae

Carex pauciflora - Betula nana

Sphagnum spp. - Carex rotundata

Empetrum nigrum - Ledum palustre ssp. decumbens

K4

STARICHKOF

DOROSHIN

HISTOSOLS

Picea mariana / Ledum palustre ssp. decumbens

Picea mariana / Equisetum sylvaticum - Ledum palustre

HISTOSOLS are any organic soils greater than 40 cm deep.

Kettle Ecosystem Wetland Map Components:

K1: Kettle pond. If larger than 20 acres, the kettle is classified as a Lake.

K2: Water table at or very near the surface, often sedge-dominated.

K3: Deeper, more variable water table, often shrub dominated.

K4: Seasonally high water table, forested.

Table 3. Summary of Matantuska-Susitna Valley and Cook Inlet Kettle Map Unit occurrence (percentages of all wetlands).
Map Unit MatSu N Cook Inlet N Mat Su Hectares Cook Inlet Hectares Mat Su % Polygons Cook Inlet % Polygons Mat Su % Area Cook Inlet % Area
K1 244 428 454 977 3.67 1.78 1.06 0.52
K12 15 59 42 330 0.23 0.25 0.10 0.18
K12c 1 1 8 8 0.02 0.00 0.02 0.00
K13 2 21 0.7 101 0.03 0.09 0.00 0.05
K1-3 34 219 109 1395 0.51 0.91 0.25 0.74
K14 1 1 0.5 0.5 0.02 0.00 0.00 0.00
K1-4 6 36 29 257 0.09 0.15 0.07 0.14
K14d 1 1 3.6 3.6 0.02 0.00 0.01 0.00
K1c 9 16 8.8 85 0.14 0.07 0.02 0.05
K1d 3 3 18 18 0.05 0.01 0.04 0.01
K2 189 390 466 1257 2.84 1.62 1.09 0.67
K21 33 111 107 602 0.50 0.46 0.25 0.32
K21c 1 1 0.5 0.5 0.02 0.00 0.00 0.00
K21d 1 1 5.4 5.4 0.02 0.00 0.01 0.00
K23 156 475 539 2155 2.35 1.97 1.26 1.15
K23c   1   1.11   0.00   0.00
K23d 4 4 16 16 0.06 0.02 0.04 0.01
K24 14 25 26 69 0.21 0.10 0.06 0.04
K2-4 91 194 462 1058 1.37 0.81 1.08 0.56
K2-4c 1 1 2 2 0.02 0.00 0.00 0.00
K2-4d 1 2 3.3 4.0 0.02 0.01 0.01 0.00
K2c   2   11   0.01   0.01
K3 217 900 317 2031 3.27 3.74 0.74 1.08
K31 7 17 11 58 0.11 0.07 0.03 0.03
K31d 1 1 1 1 0.02 0.00 0.00 0.00
K32 131 402 316 1460 1.97 1.67 0.74 0.78
K32d 1 1 1.2 1.2 0.02 0.00 0.00 0.00
K34 128 654 377 2730 1.93 2.72 0.88 1.45
K34d   2   4.8   0.01   0.00
K3d 1 7 0.3 3.0 0.02 0.03 0.00 0.00
K4 435 1141 2259 5813 6.55 4.74 5.29 3.10
K41 2 2 0.8 0.8 0.03 0.01 0.00 0.00
K42 15 25 47 119 0.23 0.10 0.11 0.06
K43 180 589 1006 3164 2.71 2.45 2.36 1.69
K43d 2 2 9.3 9.3 0.03 0.01 0.02 0.00
K4d 19 22 70 77 0.29 0.09 0.16 0.04

 

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Downloads:

Shapefile

Delineation manual

Methods, metadata

Maps and posters


Contact:
Mike Gracz
Kenai Watershed Forum 
PO Box 15301
Fritz Creek, AK  99603
907-235-2218
13 January, 2010
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