The Grazing Response Index (GRI) is a simple method to evaluate grazing management using three criteria: frequency of defoliation, grazing intensity, and opportunity for plant growth. The document provides details on calculating scores for each criterion and how they are combined for an overall GRI score. It discusses examples of using the GRI on different grazing allotments over multiple years. The GRI is presented as a tool that can assess grazing impacts annually and help inform future grazing plans, while filling a need for an evaluation method focused specifically on grazing management.

1. The Grazing
Response Index
A Simple and Effective Method to Evaluate
Grazing Management
Shane Green NRCS
With many slides borrowed from Dave Bradford, USFS ret.

2. GRI History
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Developed by CSU Extension (Roy Roath)
Early implementation by USFS (Dave
Bradford, Floyd Reed)
1999 Rangelands Article

3. GRI in Agency Technical References

4. Grazing Response Index

The GRI is used to assess the effects of
grazing during the growing season, using
the following criteria:

Frequency (measured by Duration) of
grazing.

Intensity of grazing.

Opportunity for growth before grazing OR regrowth following grazing.

5. Frequency
The number of times a plant is defoliated during
active growth.





Normally figure one defoliation every 7 days, during
active growth.
As growth slows down figure one defoliation every 10
days, or longer depending on actual growth periods.
One defoliation is positive and rates
+1
Two defoliations is neutral and rates
0
Three or more defoliations is negative and rates -1

6. Intensity
The amount of leaf material removed during the
grazing period. The key point being the amount
of leaf material left for the plant to continue
photosynthesis.




Light defoliation (> 65% leaf material remaining) +1
Moderate
(50-64% leaf material remaining) 0
Heavy defoliation (< 50% leaf material remaining) -1
Generally a grazing intensity of <50% of leaf material
removed allows the plant to meet it’s needs and
continue growth.

7. Opportunity
For plant growth and/or regrowth .

This criteria carries double the value of the frequency
and intensity criteria.
Full season to grow/regrow
+2
Most of season
+1
Some chance
0
Little chance
-1
No chance
-2

This incorporates Time and Duration of grazing.

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

8. What Does the GRI Do?


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The values are additive, providing a
positive, neutral, or negative rating for
assessing the grazing impacts for the
year.
This gives you an assessment of how your
grazing strategy worked this year.
Provides a basis for planning next year’s
grazing use.
Accounts for more than just utilization to
assess grazing effects

9. What the GRI does not do


Monitor or assess rangeland plant
communities or processes
Replacement for vegetation monitoring
and assessment

10. Graphic
Ecological
Processes
Plants
Grazing
Grazing Response
Index GRI
Utilization
Remote
Sensing
Apparent
Trend
Similarity Index
(Range Condition)
SVAP
Interpreting
Indicators
of Rangeland
Health
Proper
Functioning
Condition
PFC
Weather
and
Climate
Trend
Photo Plots,
Cover, Nested Frequency,
Species composition
Multiple
Indicator
Monitoring
MIM
Soil
Survey
Assessment
Monitoring

11. Where does GRI fit in to our
work?



Stock and monitor approach
Lots of tools to monitor the land and
plants
Lack tools to evaluate grazing – GRI helps
to fill this void.

12. Example 1:
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The first example shows the Oak Ridge (BLM)
allotment (left side of fence) and the West Elk
(FS) allotment (right side of fence).
Both allotments are managed with multi-pasture
grazing strategies.
Oak Ridge is grazed by 305 cow/calf
pairs, owned by 2 permittees, from 5/106/15, with 10 pastures.
West Elk is grazed by 1250 cow/calf
pairs, owned by 7 permittees, from 5/1510/10, with 30 pastures.

13. Oak Ridge (BLM)/West Elk (FS)
Prior to grazing
5-13-1999

14. Oak Ridge (L)/ West Elk (R), 6-4-99
Grazed 5/21-5/26/1999 / Ungrazed

15. Oak Ridge (L)/ West Elk (R), 7-9-99
45 days post-grazing / Ungrazed

16. Oak Ridge (L)/ West Elk (R), 9-9-99
105 days post-grazing / Ungrazed

17. Oak Ridge (L)/West Elk (R),10-20-99
145 days post-grazing / Grazed 9/20-10/10

18. How Would the GRI Rate This ?
1999
Oak Ridge
Frequency
Intensity
Opportunity
Total Response
West Elk
Frequency
Intensity
Opportunity
Total Response
+1
0
+1
+2
0
0
+2
+2

19. Do these Grazing Responses relate
to Range Trend?
Oak Ridge
West Elk
7-23-91

20. Oak Ridge (L)/West Elk (R),
7-23-1991
8-10-2001

21. Example 3:


This example shows Bear Trap Park on the
Dyer allotment.
This example is based on historic photo
monitoring, looking at three years 1948,
2000 and 2001.

24. Dyer C&H Bear Trap Park
10/15/1948
Allotment grazed seasonlong, 5/16-10/15, by 1,048
cow/calf pairs for 5,240
AUMs. SR – 3.0 acres/AUM.
Precipitation for season was
105%.
10/12/2000
Allotment grazed multipasture rotation, 6/1610/10, by 425 cow/calf pairs
for 2,150 AUMs. This
pasture grazed 8/11-10/05 in
2000.
SR – 5.8 acres/AUM.
Precipitation for season was

25. Dyer C&H Bear Trap Park
10/15/1948
Allotment grazed seasonlong, 5/16-10/15, by 1048
cow/calf pairs for 5,240
AUMs. SR – 3.0 acres/AUM.
Precipitation for season was
105%.
10/15/2001
Allotment grazed multipasture rotation, 6/16-10/10,
by 375 cow/calf pairs for
2,150 AUMs. This pasture
rested in 2001.
SR – 5.8 acres/AUM.
Precipitation for season was
89%.

26. How Would the GRI Rate This ?
Dyer Allotment
1948
2000
2001
Frequency
-1
-1
+1
Intensity
-1
-1
+1
Opportunity
-2
+1
+2
Total Grazing Response
-4
-1
+4

27. Example 4:
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This example shows Corral Creek on the
Corral Gulch Pasture on the Mesa
allotment.
This allotment is managed using a multipasture grazing strategy.
The allotment is grazed by 2,000 cow-calf
pairs/yearlings, 6/26-10/20.

28. The Black Mesa Story
Corral Gulch
9/1/1992

29. Mesa C&H
Lower Mesa Unit
8/12/1991

30. Mesa C&H
Upper Mesa Unit
8/2/1991 35% Use

34. How Would the GRI Rate This ?
Mesa Allotment
Corral Gulch Pasture
Frequency
Intensity
Opportunity
Total Grazing Response
1995
2007
0
0
+1
+1
0
0
+1
+1

35. Summary of Grazing Response Values on Corral Gulch
Pasture of Mesa C&H Allotment, 1995-2007
95 96 97 98 99 00 01 02 03 04 05 06 07
F
0
0
0 +1 0 +1 -1
I
0
0
0
0
-1
0
0
0
0
0
-1
0
-1 +1 0
0
0 +1 0
O +1 +1 +1 +1 +1 -1 +1 -1
0 +1 +1 +1 +1
T +1 +1 +1 +2 0
0 +1 +1 +1 +1
0
-1
0

36. Summary of Grazing Response
Values on Corral Gulch Pasture of
Mesa C&H Allotment, 1995-2007:

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Positive values 8 of 13 years (62%).
Neutral values 4 of 13 years (31%).
Negative values 1 of 13 years (7%).
Grazing Responses can and do relate
to long-term vegetative trend.

37. Mesa C&H
Corral Gulch 9-25-1995
Grazed 7/25-8/08 (15 days)
by1,782 cow/calf pairs &
155 yearlings.
313 mm Growing season
precipitation or 169%.
10-10-2007
Grazed 7/15-7/29 (15 days)
by1,883 cow/calf pairs 104
yearlings.
215mm Growing season
precipitation or 116%.

38. Dry Fork C&H Allotment Example
oAllotment consists of 31,000 acres of
which 16,000 are considered unsuitable to
grazing.
oThe allotment is grazed by up to 630
cattle owned by 5 different permittees.
oThe allotment has nine pastures, that are
grazed from 3 to 32 days.
oCattle graze the Deer Creek/Apache
pasture first every year; graze the
Sherwood pasture every other year and
graze the Ditch pasture last every year.

39. Summary of GRI Values on Apache Rocks – Deer Creek
Pasture of Dry Fork C& H Allotment, 1998-2009
98 99 00 01 02 03 04 05 06 07 08 09
-1
0
I
-1
0
0
0
-1
O
0
T
-2
+1 +2
+1 +2
-1 -1
-2 -2
-1
0
0
-1
No Data
0
Pasture rested
0
No Data
-1
No Data
F
0
-1
+1 +1 0
-1 +1 -1

40. Summary of Grazing Response Values
on Apache Rocks-Deer Creek Pasture of
Dry Fork C&H Allotment, 1998-2009:
(Data available for 8 of 12 years)

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Positive values 3 of 8 years (38%).
Neutral values 0 of 8 (0%).
Negative values 5 of 8 years (62%).
Grazing Responses can and do relate
to long-term vegetative trend.

41. Dry Fork C&H
Deer Creek Pasture
Deer Creek CM West View
6/18/1999
14 plant species
40% smooth brome
30% Kentucky bluegrass
Trace wheatgrass
Trend uncertain.
Dry Fork C&H
Deer Creek Pasture
Deer Creek CM West View
6/15/2009
21 plant species
80% smooth brome
5% Kentucky bluegrass
Trace wheatgrass &Baltic rush
Trend slightly upward.

42. Summary of GRI Values on Sherwood Pasture of Dry
Fork C& H Allotment, 1998-2009
98 99 00 01 02 03 04 05 06 07 08 09
F
+2
+1
+2
0
0
0
+1
Pasture rested
+3
+1
+1
0
Pasture rested
+2
0
0
Pasture rested
0
+1
Pasture rested
Pasture rested
T
No Data
O
Pasture rested
I
+1
0
+1
+2

43. Summary of Grazing Response Values
on Sherwood Pasture of Dry Fork C&H
Allotment, 1998-2009:
(Data available for 11 of 12 years)
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Positive values 4 of 6 years pasture was grazed
(67%).
Neutral value 1 of 6 years pasture was grazed
(17%).
Negative values 0 of 8 years (0%).
No data 1 of 8 years pasture was grazed (16%)
Pasture rested 6 of 12 years (50%).

44. Dry Fork C&H
Sherwood Pasture
Elijah’s Park CM East View
6/18/1999
22 plant species
35% Kentucky bluegrass
20%western wheatgrass
Trace Letterman needlegrass
Trend estimated upward.
Dry Fork C&H
Sherwood Pasture
Elijah’s Park CM East View
6/18/2009
29 plant species
25% Kentucky bluegrass
5% western wheatgrass
5% Letterman needlegrass
Trend upward.

45. Dry Fork C&H
Sherwood Pasture
Elijah’s Park CM East View
6/18/2009
Pasture grazed from
7/6-18/2009
by ~500 head of cattle.
Dry Fork C&H
Sherwood Pasture
Elijah’s Park CM East View
10/07/2009
GRI Rating
F = +1 (13 days)
I = 0 (moderate)
O = +1 (most of season)
TGRI = +2

46. Summary of GRI Values on Ditch Pasture of
Dry Fork C& H Allotment, 1998-2009
98 99 00 01 02 03 04 05 06 07 08 09
+1 0 +1 +1 -1
+1
I
0
-1 -1
+1 +1 +1 +1 -1
+1
O
-1
T
0
+1 +1
+1 0
+2 +2 +2 -2 -2
+4 +3 +4 0
-1
No Data
+1 0
No Data
+1
No Data
F
-1
+1

47. Summary of Grazing Response Values
on Ditch Pasture of Dry Fork C&H
Allotment, 1998-2009:
(Data available for 9 of 12 years)
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Positive values 5 of 9 years (55%).
Neutral values 3 of 9 (33%).
Negative values 1 of 8 years (12%).

48. Dry Fork C&H
Ditch Pasture
Upper Poison Gulch CM NE view
6/18/1999
22 plant species
30% smooth brome
70% Kentucky bluegrass
Trace Columbia needlegrass
Trend estimated upward.
Dry Fork C&H
Ditch Pasture
Upper Poison Gulch CM NE view
7/23/2009
38 plant species
30% smooth brome
40% Kentucky bluegrass
7% Columbia needlegrass
Trend upward.

49. Grazing Response Index Summary:
The GRI is used to assess grazing management
using the following 3 criteria:



Frequency (measured by duration) - The number of
times a plant is defoliated during active growth.
Intensity - The amount of leaf material removed during
the grazing period. The key point being the amount of
leaf material left for the plant to continue
photosynthesis.
Opportunity For plant growth before grazing and/or
re-growth following grazing.

50. Summary, continued:

Easy to understand and communicate.


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Allows specialists summarize and communicate a
more comprehensive picture of grazing
management effects
Fills a void in the landscape of monitoring and
evaluation tools with a focus on the management
rather than the resource.
Considers more than just utilization

Incorporates stock density, time and duration of
grazing, and plant growth and re-growth.

51. Summary, continued:


Provides a basis for adjusting grazing in
subsequent years.
GRI evaluations should correlate to longterm trend monitoring.

52. Where to take GRI from here

Proposed refinements

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Geographic fine tuning
Adding an evaluation factor for physiological
stage of plant growth when grazed
Agency collaboration and endorsement

Need for an update and published interagency
technical reference, akin to the Interpreting
Indicators of Rangeland Health or Creeks and
Communities efforts.

53. Are There Any Questions
?