Relating Post-Treatment Vegetation Responses to Habitat Requirements of Gunnison Sage-grouse

Dr. Joe BrummerColorado State University

Department of Soil and Crop Sciencesand

John ScottNatural Resources Conservation Service

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

• 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

Methodology

• 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

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

Spike 20P Herbicide

Spike 20P Herbicide1994

1996

• 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

2,4-D Herbicide

Minimum suggested cover for sagebrush (15%)

2,4-D Herbicide2003

1994

• 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

Brushmowing

Minimum suggested cover for grasses (10%)

Minimum suggested cover for forbs (5%)

Brushmowing

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

to treated

• 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

Fire (Prescribed and Wild)

Fire (Prescribed and Wild)

1988

1998 – Note forb response

1984

Note lack of sagebrush recovery

• 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

Summary

Gunnison Tornado??