The HGM reference approach is alive

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The HGM (reference) approach is alive well on
the West Coast
Dr. Paul Adamus, his grad students and
collaborators recent ongoing projects
Island County, WA (n 140 sites)
Oregon Coast (n 120)
Willamette Basin (n 109)
Crater Lake National Park (n 75)
Agate Desert vernal pools (n 30)
Lassen Vol. National Park (n 75)
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Oregons tidal wetland HGM classification

• River-sourced
• Usually fresher
• On a channel

• Marine-sourced High
• Tidal inundation at least once annually
• Characteristic plants

• Marine-sourced Low
• Inundated by tide most days during a month
• Characteristic plants
• No woody vegetation

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Regional Reference Data
331 polygons selected 128 public 203
private (266 distinct owners) 87 (43)
allowed access 57 (28) denied access
59 (29) no reply or decision Result 120
sites assessed 47 Marine-sourced Low Marsh
42 Marine-sourced High Marsh 31 River-sourced
Tidal Wetland

• Products available
• Quantitative definitions of what Oregon tidal
  wetlands should look like.
• Rapid methods to score Risk, Condition, and
  Functions of Oregon tidal marshes.
• Rankings of 120 tidal wetlands for these
  attributes ( 20 of total tidal wetlands).
• Improved coastwide maps, with HGM labels on all
  tidal wetlands.
• Coastwide maps of Restoration Opportunity
  Areas (e.g., diked non-tidal).
• Correlation coefficients among all paired
  variables species-area equations
• Quantitative definitions of where various
  non-tidal wetland types should occur
• (landscape settings) in coastal watersheds.

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COE National HGM Flooding duration, marsh width,
microtopography, aquatic edge (connected, all),
upland edge, bare percent, non-native plant
cover, vegetation similarity index, number of
vegetation forms/ habitat types
Oregon HGM most of above, plus Geomorphic
indicators Soil texture, tidal channel
complexity, channel width-depth ratio, edge
transition angle, wood (drift, in-channel,
on-marsh), shade, fetch, island, freshwater
tributaries seeps. Landscape estuary type,
position in estuary, special adjoining habitats
(alder, eelgrass, mudflats, potential roost
sites, pasture ponds). Botanical indicators
(regression-adjusted) Species deficit per
quadrat, Frequency of quadrats with non-natives
dominant, high overall dominance, annual
species. Mean percent-cover of plants that are
tuft-rooted, tap-rooted, stoloniferous. Risk
Potential sources of Contaminants, nutrients,
sediment erosion/ compaction, hydrologic
disruption, buffer width, traffic (boats, roads,
humans on foot), exotic invertebrates
Which indicators (as estimated) are sensitive to
the human alteration gradient (as
estimated)? Exactly how suitable is each
indicator for distinguishing human vs. natural
influences?
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• Evaluating variables for use as indicators
• Magnitude and consistency of statistically
  significant differences between
• Least-altered vs. other sites, w. w/o HGM
  subclassification
• Less-altered vs. other sites , w. w/o HGM
  subclassification
• Percent of the comparisons that were
  statistically significant consistent
• With indices presumed to indicate Risk (e.g.,
  grazing)
• With variables that define Wetland Integrity
• (e.g., non-native plant cover)

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Whats different about Oregon tidal wetlands?
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Oregon method, digital maps, guidebook
available in September. Email
adamus7_at_comcast.net

• In summary
• We collected a large reference data set useful
  for restoration evaluation site ranking.
• We created function scoring models that
  represent Best Available Science, are
• regionally-sensitive, and practical to use.
• We found few functionally-important variables
  that correlated with site naturalness.
• This depended strongly on how the variables
  naturalness were defined estimated.
• Statistical correlation with wetland
  naturalness although worthwhile to examine
• should not be required before deploying HGM
  models that presume only to score functions.
• Correlation is not enough to validate use of a
  variable as an indicator of naturalness.
• The assumptions should be scrutinized carefully.

Credits USEPA Region 10, Oregon Dept. of State
Lands, Coos Watershed Association, Oregon State
University