jen chutz, dci west biological consulting linda vance, montana natural heritage program montana...
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Groundwater-dependent wetlands in Western Montana Forests
Jen Chutz, DCI West Biological ConsultingLinda Vance, Montana Natural Heritage
ProgramMontana Wetland Council
March 26, 2014
BackgroundEPA-funded project designed to…Document extent of
Groundwater Dependent Ecosystems (GDEs)• Especially fens, focusing on
Western Montana
Enhance MTNHP’s wetland reference network
Improve recognition of patterns in imagery to assist in USFWS National Wetland Inventory (NWI) mapping
So how do you find GDEs? Expert knowledge
• Many of the largest and richest fens have been identified and surveyed, and are known to botanists and land managers, or described in publications
Trial and error• In theory, in the course of enough wetland surveys,
including getting to and from target wetlands, you’ll encounter GDEs
National Wetland Inventory (NWI) mapping and high-resolution imagery• Our preferred approach!
3.21.2014: 1,726 USGS 24K Quads Mapped2,178,028 Acres
Wetlands: 1,655,061 AcresRiparian: 522,967 Acres
Using the NWI to find GDEs/FensBecause NWI maps are based
on aerial imagery, key indicators like the presence of peat aren’t detectable
However, GDEs generally…• Have no inlet
• Often have no outlet
• Have a fairly distinct “signature” visible to the human eye because they are often saturated through the growing season
Using the NWI to find GDEs/FensAlthough GDEs found from
floodplains to alpine areas in MT…
GDEs generally are found…• At low points in the landscape
OR…
• Near slopes where groundwater intercepts surface
• Associated with glacial till/outwash, alluvial fans/basins, floodplains
• Over limestone deposits
Used NWI mapping in ArcGIS to identify ALL:• Palustrine
Emergent wetlands AND…
• Palustrine Shrub Scrub wetlands WITH…
• Saturated water regimes
• PEMB and PSSB
North of Whitefish, MT
Field surveysRapid assessments (Level 2)• ~ 2 hours
Intensive assessments (Level 3)• Up to 8 hours
Field surveysSet up 0.5 hectare Assessment
Area (AA)• Best represents site• Diversity & proportions
• Usually 40m circle
Site info: • General wetland description• Landscape setting• Physical patch types• AA drawing• Photos & GPS points
Classification of AA• Ecological Systems of MT• Hydrogeomorphic (HGM)
class• Cowardin classification
Field surveysHydrologic
inputs/outlets• If any
Major vegetation zones• Structure and
species composition
Anthropogenic disturbance metrics:• Distance to, degree of, cause
of disturbance/changes to… Landscape Vegetation
GDEs sustained by inputs from local landscape
GDEs are stable, but not resilient
Soil Hydrolog
y
Soil surveysMin. 2 soil pits, each in different
vegetation & hydrology, if possible• Min. 60 cm or until mineral soil
Soil Texture - Organic vs. Mineral • Peat, mucky peat, muck• Ribbon test…Sand Loam Clay Loam
Clay
Other hydric soil indicators• Redox concentrations and depletions (Fe &
Mn)• Hydrogen Sulfide
Soil Color – Munsell Soil Color Chart
Level 3: Intensive assessmentsWithin AA, we lay out ten
10x10m modules
Within 4 selected modules, record…• Vegetation species…• Presence• Stratum• % canopy cover
• Ground Cover…• Type• Deep water, gravel,
litter, woody debris, etc…
• % cover• Depth
50 m
20 m
0 m
#10
#1 #2 #3 #4 #5
#6 #7 #8 #9
50 m
XP1
XP2
AA & Plot Placement
GDEs vs FensNot all GDEs are fens, and not all
fens are GDEs
Fens are defined as having an organic layer with ≥40cm of peat
GDEs rely on groundwater for the majority of their water input• But, we encountered many
flow-through fens, some distinct channels
• Must “dig” for indicators of groundwater dependency• Soil, pH, landscape, etc…
GDE 131 GDE 131, our earlier example, was classified as a wet meadow rather than a fen, although it was a close call.
Soil pits had from 14-25 cm of peat, some with mucky peat underneath, some with a silty loam
Vegetation cover was primarily Carex utriculata, C. atherodes, and Calamagrostis canadensis
Project summaryIn total from 2012 & 2013, we completed intensive
surveys of… • 131 GDEs• 109 fens• 19 wet meadows• 3 emergent marshes
Identified 350 species in the Assessment Areas of these GDEs
Fens• AA vascular plant species richness varied widely
• From 1 to 44 species identified per fen• Mean of 16.4 species
Project summaryNativity was high:
• 77 of the fens had no observed exotic species• Only one –in Glacier National Park– had more than
4
For fens, Mean Floristic Quality Index = 58• This was adjusted for cover weight and native
species• Very near the value of 60.6 MTNHP found for
reference-standard fens in an earlier study
Next stepsSpecies of Concern (SOC) plant data will be entered into
MTNHP databases once all IDs are confirmed
Final report on project will be available from MTNHP by late April
Database and GIS available on request from MTNHP• Contact: Linda Vance [email protected]
Data forms and protocol are available on MTNHP’s website• http://mtnhp.org/wetlands/