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Not “tree cover,” but instream physical structure
Instream Cover or Stucture
Cover
Max 20
2]I NSTREAM COVER(Structure)
(Give each cover type a score of 0 to 3; see back for instructions) AMOUNT: (Check ONLY One orTYPE: Score All That Occur check 2 and AVERAGE )
___UNDERCUT BANKS [1] ___POOLS>70 cm [2] ___OXBOWS, BACKWATERS [1] - EXTENSIVE >75%[11]___OVERHANGING VEGETATION [1] ___ROOTWADS [1] ___AQUATIC MACROPHYTES[1] - MODERATE 25-75%[7]___SHALLOWS(IN SLOW WATER) [1] ___BOULDERS [1] ___LOGS OR WOODY DEBRIS [1] - SPARSE 5-25% [3]___ROOTMATS [1] COMMENTS:______________________________________________ - NEARLY ABSENT <5%[1]3] CHANNEL MORPHOLOGY: (Check ONLY One PER Category OR check 2 andAVERAGE )
Previous threshold for check box for a given cover type was low (~5%)
Overall cover metric and number of cover types correlated with IBI, but individual cover type quality not rated well
Each cover type scored from 0-3 points based on standard definition
Still scoring based on old method also, will phase out next year; need to calibrate new method to old data
Newer Cover Scoring Procedure
Instructions for scoring the alternate cover metric: Each cover type should receive a score of between 0 and 3, Where:
0 - Cover type absent; 1 - Cover type present in very small amounts or
if more common of marginal quality; 2 - Cover type present in moderate amounts, but
not of highest quality or in small amounts of highest quality;
3 - Cover type of highest quality in moderate or greater amounts. Examples of highest quality include very large boulders in deep or fast water, large diameter logs that are stable, well developed rootwads in deep/fast water, or deep, well-defined, functional pools.
New Cover Metric
Amount of Cover
Rootwads/Logs
High Quality Rootwad
Sycamore among the best quality
Large diameter roots
Best when in deep water
Best when in or adjacent to fast water
Aquatic Macrophytes
0
0.2
0.4
0.6
0.8
1
Absent Present Absent Present
Tot
al P
hosp
horu
s
Aquatic PlantsOxbows, Backwaters,
Sidechannels
N = 303 N = 106 N = 399
N = 10
Only macrophytes, not algae or diatoms
Emergent or submergent Great nursery areas Improve riffle quality by
making riffles narrower and deeper
Boulders Examine all
cover types to determine whether they are functional!
Functional Boulder: In Deep
Fast Water
Non-Functional Boulder: In Shallow Water & Embedded
Undercut Banks Needs to be in deep enough water and undercut enough to
provide function as cover If undercut is part of rootwad count as rootwad, not as undercut
Rootmats
Fine fibrous roots of willows and other plants
Small fish may use these as cover or feed on invertebrates that colonize them
Logs and Woody Debris
Habitat forming functions
Fish cover Macroinvertebrat
e production, especially in big rivers
Bank protection
Overhanging Vegetation
Shading Refuge from avian
predators (e.g., kingfishers, herons)
Terrestrial food Does not include
high canopy
Oxbows, Backwaters, & Side Channels
10
20
30
40
50
60
Absent Present Absent Present
IBI
Aquatic PlantsOxbows, Backwaters,
Sidechannels
N = 317
N = 105
N = 431
N = 10
Oxbows, backwaters, and side channels are excellent nursery habitat
Sequester/transform nutrients Spawning areas (e.g., northern pike, muskie)
Oxbow
Backwater
Shallows in Slow Water Y-O-Y fish use margin areas to feed
and escape predators
Cover vs IBI
10
20
30
40
50
60
0-4 5-8 9-12 13-16 17-20
IBI
Cover Metric Score10
20
30
40
50
60
0 5 10 15 20
Data by Site All YearsECBP & HELP EcoregionsReference Sites ONLY
y = 22.08 + 1.44x
R2= 0.33
Sit
e S
peci
fic
IBI
Site Specific QHEICover Score
1
10
100
0 1 2 3
Spotted Bass vs Logs and Woody Debris Score
Rel
ativ
e N
umber
Logs and Woody Debris Score (0-3)
Benefits of New Scoring Approach
Spotted Bass
1
10
100
0 1 2 3
Smallmouth Bass vs Boulder Cover
Rel
ativ
e N
umber
Boulder Cover Score (0-3)
1
10
100
0 1 2 3
Green Sunfish vs Boulder Cover
Rel
ativ
e N
umber
Boulder Cover Score (0-3)
Habitat Generalist: Green Sunfish
