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.