case study: adaptive grazing management at rancho...
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CASE STUDY:
ADAPTIVE GRAZING
MANAGEMENT AT
RANCHO LARGO CATTLE CO.
Grady Grissom, Rancho Largo Cattle Co.
Tim Steffens, USDA Natural Resource Conservation Service
“Rotational Grazing [SYSTEMS] as a
means to increase vegetation and
animal production has been
subjected to as rigorous a testing as
any hypothesis in the rangeland
profession, and it has been found to
convey few, if any, consistent
benefits over continuous grazing”
(Briske etal. 2008).
Does it Matter?
“Species composition of plant communities can be
modified in response to the frequency, intensity, and
seasonality of grazing.”
“Rest and deferment to promote plant growth is the
most fundamental and long-standing corollary of
the unifying principles…”
(Briske et al. 2008)
“Experimental grazing research
embodies a fundamental tradeoff
between a robust assessment of ecological
processes and the ability to mimic the
responses associated with adaptive
management” (Briske et al. 2011).
Adaptive Management = “Plan – monitor – Re-plan”
(Savory 1988)
WHAT ADAPTATIONS ARE
MANAGERS MAKING?
Tim Steffens:
General Principles
Here:
Specific Examples of Adaptation
(Thought Process and Management Action)
Why?
Systems Fail versus Adaptation
Science versus Management
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010-40
-30
-20
-10
0
10
20
30
40
Cattle
P
erc
en
t R
etu
rn
o
n Inve
stm
en
t (R
OI)
Sto
ck
in
g R
ate
(A
UD
/h
a)
An
nu
al P
re
cip
itatio
n (c
m)
De
fe
rra
l L
en
gth
(d
ays)
100
200
300
Overstocked
Adaptation
Process-based Grazing
Avg. Stocking Rate
Avg. Precip.
Avg. Precip.
Avg. Precip.
Avg. Stocking Rate
Avg. Stocking Rate
ROI Cattle
Length of Deferral
Economic, Grazing, and Precipitation Data:
Production/Cattle
Focus
Maximize stocking
rate to cover high
overhead.
Management Paradigm:
Time (years)
Conclusions from Early Years:
1)Grazing Systems do not mitigate overstocking.
2)”Economic review” works.
ADAPTATION #1
Action: Change to Ecological
management paradigm (mental model)
Goal: Improve secondary production
through ecological health (Hypothesis)
Mechanism: Unknown
All private managers are adaptive…
but not necessarily with an ecological paradigm
The move to an ecological focus was
driven by a failed grazing system
1999
2000
Ecological
Appraisal:
1)Low Residual, low
litter- Poor capture and
retention of water
Poor mineral Cycle
2)Gramma Grass
Dominated- • <20% cool season
grasses Ranch wide
• Winterfat and 4 wing Salt
bush only in specific
locations
• Blue Stem, Vine Mesquite-
only specific locations
• Green Needle – not
observed
Action: Decrease Stocking Rate
(1999 – 2000)
ADAPTATION #2:
Goal: Improved water cycle
Mechanism:
1. Improved animal performance from decreased
competition for forage
2. Increased residuals cause improved water
capture and infiltration
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010-40
-30
-20
-10
0
10
20
30
40
Cattle
P
erc
en
t R
etu
rn
o
n Inve
stm
en
t (R
OI)
Sto
ck
in
g R
ate
(A
UD
/h
a)
An
nu
al P
re
cip
itatio
n (c
m)
De
fe
rra
l L
en
gth
(d
ays)
100
200
300
Overstocked
Adaptation
Process-based Grazing
Avg. Stocking Rate
Avg. Precip.
Avg. Precip.
Avg. Precip.
Avg. Stocking Rate
Avg. Stocking Rate
ROI Cattle
Length of Deferral
Economic, Grazing, and Precipitation Data:
Time (years)
Reduced stocking to
improve animal
performance and water
cycle
Management Paradigm:
Ecological
Adaptation #3
Cross fence to increase stock density
(2000 – 2001)
1. Ecological goal = Improved mineral cycle
2. Ecological process intervention = space/time
density of manure and urine
2000-2001
1. No change in spatial manure density
2. Minimal recovery of flagged defoliated plants
(Ungrazed period versus recovery period)
1) Focus on plant health and diversity
versus mineral cycle.
A) Look at plant monitoring
B) Look at scientific literature
C) Education from other
producers/technicians
1. Plant growth is sporadic (Torell et al. 2011)
2. Short grass = < 1cm/week maximum
3. Mid-grasses = > 3cm/week maximum
4. Dry year = <5% seed production
5. Normal year = 20-40% seed production
6. 1 defoliation = no seed production
Was species mix ( <20% cool season)
driven by grazing?
Large body of data (eg Hart and Ashby, 1998) :
1) Blue Gramma increased with grazing intensity
2) Western Wheat and Needle and Thread decreased with
grazing intensity
3) Neighbors water limited pastures 50-60% cool season
4) Technicians suggested 90 –100 day recovery Most grazing studies were May or June to Oct. grazing…They missed most cool season consumption.
ADAPTATION #4
Action: Plan for minimum 100-day recovery periods
(Facilitated by cross fencing)
Goal: Improve plant diversity
(Specifically – cool season grasses)
1)Mechanism: Leave a large portion of the plants on
the ranch un-defoliated each growing season. A) Assume seed production and seedling/tiller
survival are limiting processes.
B) Assume plant maturity would promote vegetative
and sexual reproduction.
9 Pastures to 36 Pastures
Strategy: Defer to allow reproduction:
Increase Deferral to minimum 100 Days
36 pastures allowed 100-day recovery with reasonably
short graze periods. (Recall 3cm/week)
Corollaries before monitoring results:
Long deferral was a land mark, but it misses the point…
Key Point: plant physiology not time measures recovery.
Corollary Adaptation #1: Return to pastures is measured by ecological criteria:
1. Plant physiology of desired plants
2. Residual and litter cover
3. Seasonality of previous graze period
4. Weather events
Grazing Response Index (Reed et al. 1999)
Corollary #2: Animal selection matters
Monitoring Data:
Corollary #3: Seasonality matters
Corollary #4: Variable stocking rates
help (mix cow-calf, yearling, custom graze)
Month
1 2 3 4 5 6 7 8 9 10 110
10
20
30
40
50
60
70
80
90
% P
lants D
efoliated in
a G
raze P
erio
d
(A
ve
ra
ged
b
y M
on
th
2
01
0)
Blue Gramma
Western Wheat
ADAPTATION #2:
SEASONAL DEFOLIATION PATTERNS
Ja
n
Nov
Ap
ril
Fall/Dormant defoliation 2007
(120 days deferral)
March 19, 2008
Early March defoliation
2007
Selectivity and seasonality make grazing
processes plant specific.
So
Grazing strategies and variables must be plant
specific.
1. Annual stocking rate is an important variable but, it
is a simple variable in a complex system.
2. Selectivity and seasonality require variables like
season specific and species specific grazing
intensity.
All grazing is targeted so management must be
targeted.
“Continuous grazing at moderate stocking
allows adequate deferral of plants. Deferral
occurs because 50% of the plants remain un-
defoliated.”
What about diversity and animal selection?
Month
% P
la
nts D
efo
liated
in
a
G
ra
ze
P
erio
d
(A
vera
ged by M
onth 2
010)
1 2 3 4 5 6 7 8 9 10 110
10
20
30
40
50
60
70
80
90
Western Wheat
Blue Gramma
Squirrel Tail Winterfat
Ja
n
Nov
Ap
ril
Species Abundance Threshold
April, 2008
October, 2008
0
10
20
30
40
50
60
70
80
90
100
Pastures Grazed Before June
30, 2010
Pastures Grazed after June
30, 2010
Percent plants with Seed Production
Seed production
data gathered
Fall 2010.
0
10
20
30
40
50
60
70
80
90
Grazed Jan. Feb.
2007
Grazed March
April 2007
Grazed May June
2007
Grazed July, Aug.,
Sept. 2007
% Young (<7cm) Plants Fall 2008
Timing of 2007 grazing
related to plant
recruitment spring 2008
Management can prepare for weather events:
But palatability is a function of abundance – San Louis Valley
and 4 Wing Salt Bush
Economic Response of
Process Based Adaptations?
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010-40
-30
-20
-10
0
10
20
30
40
Cattle
%
R
etu
rn
o
n Inve
stm
en
t (R
OI)
Sto
ck
in
g R
ate
(A
UD
/h
a)
An
nu
al P
re
cip
itatio
n (c
m)
De
fe
rra
l L
en
gth
(d
ays)
100
200
300
Overstocked
Adaptation
Process-based Grazing
Avg. Stocking Rate
Avg. Precip.
Avg. Precip.
Avg. Precip.
Avg. Stocking Rate
Avg. Stocking Rate
ROI Cattle
Length of Deferral
Economic, Grazing, and Precipitation Data:
YEAR
Did we Achieve the
Ecological Goal?
1999- 15% Western Wheat
2008- >50% Western Wheat
Species composition of
plant communities can
be modified in response
to the frequency,
intensity, and seasonality
of grazing.(Briske et al 2008)
Typical Winterfat occurrence late 1990’s
“Rest and deferment to promote plant growth
(reproduction) is the most fundamental and long-standing
corollary of the unifying principles…”(Briske et al 2008)
Area close to
previous slide
2010
Reversible State-transition:
Blue Gramma + Filaree +- Western Wheat
Green Needle Grass
Vine Mesquite
Side Oats
Silver Bluestem
Western Wheat
Blue Gramma
Conclusions from Case Study
1) A Grazing System was Ineffective:
2) Process based scientifically sound
adaptations were effective:
Grazing systems are a simple
solution to a complex problem
• Recovery based on plant physiology to allow
reproduction
• Varying defoliation patterns through seasonal grazing
AND
3) “…grazing experiments indicate that if
ecological benefits can be directly achieved in
these [rotational] systems (Teague et al. 2008),
they require very nuanced and specific grazing
patterns.” (Briske et al. 2011)
Hypothesis from Case Study
1) Species diversity varies positively with economic
return. Ecological health can drive secondary
production. (See Jacobo et al. 2009 and Kothman et al 1971)
2) Length of deferral vs. diversity is complex:
Complexity = Multiple
relationships between
variables
Definition of Complexity
Variable X
Va
ria
ble
Y
Inflection related to a
change of underlying
processes
Complexity = Multiple
relationships between
variables
Length of Deferral vs. Species Diversity
Length of Deferral
Sp
ec
ies
Div
ers
ity
Inflection related to
reproduction processes
100 Days 1 Year
“short
duration
grazing”
0%
10%
20%
30%
40%
50%
60%
70%
Studies with Rest
Periods > 89 Days (13)
Studies with rest
periods < 90 Days (11)
% of 24 Studies with Diversity
Data
% S
tud
ies R
ota
tio
n >
Co
nti
nu
ou
s
0%
20%
40%
60%
80%
100%
120%
Initial Seral State Low
(6)
Initial Seral State
High (10)
Initial Seral State
Unknown (8)
% of 24 Studies with Diversity Data
% S
tud
ies R
ota
tio
n >
Co
nti
nu
ou
s
Length of Recovery
Sp
ec
ies
Div
ers
ity
100 Days 1 Year
Low Initial
Diversity
High Initial
Diversity
Length of Deferral vs. Species Diversity
History matters in
complex systems
Length of Recovery
Sp
ec
ies
Div
ers
ity
Inflection related to
reproduction processes
100 Days 1 Year
“short
duration
grazing”
Length of Deferral vs. Species Diversity
Rotation vs Continuous
trials are not process-
based quantitative
science (Provenza 1991).
“continuous
grazing”
Conclusion:
1)Process based science
2)Adaptive management
3)Effective communication between
science and management (Boyd and Svejcar 2009)
Complex problems require:
We pay lip service to complexity but we ignore
it in the rotational grazing controversy.
Seasonality and return interval are
important grazing variables.