Relating PostTreatment Vegetation Responses to Habitat Requirements of Gunnison Sagegrouse

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Relating Post-Treatment Vegetation Responses to
Habitat Requirements of Gunnison Sage-grouse
Dr. Joe Brummer Colorado State University Departme
nt of Soil and Crop Sciences and John
Scott Natural Resources Conservation Service
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Methodology

• Location Gunnison Basin
• Sagebrush areas that had been recently and
  historically treated were sampled during the 2006
  growing season
• Sagebrush treatments investigated
• Spike herbicide
• 10 xeric sites
• 4 to 12 years old
• 2,4-D herbicide
• 10 mesic sites
• 1 to 15 years old
• 7 xeric sites
• 3 to 22 years old
• Brushmowing
• 8 xeric sites
• 3 to 9 years old
• Fire (prescribed and wild)
• 16 mesic sites
• 4 to 22 years old
• 12 controlled burns, 4 wildfires

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Methodology

• Sampling protocol
• 30 meter line transects
• 5 or 10 transects per area (depending on size of
  treated area)
• 10 Daubenmire quadrats (0.1 m2) per transect for
  herbaceous cover
• Variables measured
• Canopy cover of sagebrush and other shrubs by
  line intercept
• Height of sagebrush
• Canopy cover and height of grasses and forbs
• Tried to follow sampling guidelines as outlined
  in the Rangewide Conservation Plan
• Status of vegetation related to breeding habitat
  guidelines
• Control areas
• When feasible, an equal number of samples was
  taken in an adjoining untreated area

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Spike 20P Herbicide

• Chemical name Tebuthiuron
• Granular herbicide
• Systemic
• Must move into soil where it is taken up by roots
  and translocated to aerial portions of the plant
• Effective control of many brush species
• Has been used to thin big sagebrush when applied
  at low rates (0.1 to 0.5 lbs a.i./ac)
• Higher rates must be used on soils with higher OM
• Poor results in mountain big sagebrush in
  Gunnison area

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Spike 20P Herbicide

• 8 sites were treated at the 0.2 lb/ac rate
• Allowed regression over time
• 4 sites treated in 1994 at different application
  rates
• Control
• 0.2 lbs a.i./ac
• 0.3 lbs a.i./ac
• 0.4 lbs a.i./ac
• 0.5 lbs a.i./ac
• Allowed comparison among rates

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Spike 20P Herbicide
1994
1996
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2,4-D Herbicide

• Foliar contact herbicide
• Introduced in the 1940s
• Most effective when there is adequate soil
  moisture and plants are actively growing at time
  of application (2 inches of new leader growth)
• Effective control of many brush and broadleaf
  species
• For big sagebrush control, generally applied at 2
  lbs a.e./acre
• More consistent control on mesic sites
• Results often sporadic on the more xeric sites

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Minimum suggested cover for sagebrush (15)
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2,4-D Herbicide
2003
1994
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Brushmowing

• One of several potential mechanical methods of
  manipulating sagebrush
• Expensive, especially given current fuel and
  labor costs
• Confined to areas with few or no large rocks and
  fairly gentle topography
• Advantages
• Can target areas of various sizes and shapes
• Lays down litter
• Helps reduce runoff and increase infiltration of
  precipitation
• Mulch aids in establishment of grass and forb
  seedlings
• Height of mowing can be manipulated which leads
  to varying degrees of sagebrush control
• Disadvantage
• Tends to be short-lived treatment

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Minimum suggested cover for grasses (10)
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Minimum suggested cover for forbs (5)
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Brushmowing

• Treated in 2001
• Note grass response
• Transition from untreated to treated

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Fire (Prescribed and Wild)

• Natural occurrence in sagebrush ecosystems
• Main factor that historically set succession back
• Size and shape of treatment more difficult to
  control
• Suppression of sagebrush tends to be more long
  lasting compared to other treatments
• Easier to implement on more mesic sites because
  of presence of fine fuels to carry fire

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Fire (Prescribed and Wild)
1984
1988
1998 Note forb response
Note lack of sagebrush recovery
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Summary

• Sagebrush recovery
• Xeric sites (time to reach 15 cover)
• Spike 19 yrs
• 2,4-D - no relationship
• Brushmowing 12 yrs
• Mesic sites (time to reach 10 cover)
• 2,4-D 8 yrs
• Fire 36 yrs
• Grass response
• No or weak relationship to age of treatment
• Generally, significant difference between treated
  and untreated
• Majority of sites met minimum suggested cover
• Regardless of age of treatment
• Forb response
• No consistent relationship
• Spike and fire decreased with age of treatment
• 2,4-D increased with age of treatment
• Brushmowing no relationship
• Majority of sites did not meet minimum suggested
  cover

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Gunnison Tornado??