CASE STUDY: ADAPTIVE GRAZING MANAGEMENT AT RANCHO LARGO CATTLE CO.

Transcription

1 CASE STUDY: ADAPTIVE GRAZING MANAGEMENT AT : RANCHO LARGO CATTLE CO. Grady Grissom, Rancho Largo Cattle Co. Tim Steffens, USDA Natural Resource Conservation Service

2 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).

3 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)

4 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)

5 Tim Steffens: WHAT ADAPTATIONS ARE MANAGERS MAKING? General Principles Here: Specific Examples of Adaptation (Thought Process and Management Action) Why? Systems Fail versus Adaptation Science versus Management

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7 Stocking Rate (AUD/ha) Annual Precipitation (cm) Cattle Percent Return on Investment (ROI) Deferral Length (days) Economic, Grazing, and Precipitation Data: Overstocked Management Process-based Paradigm: Grazing Avg. Precip. Avg. Stocking Rate Adaptation Production/Cattle Avg. Precip. Focus Avg. Precip. Avg. Stocking Rate ROI Cattle Length of Deferral Maximize stocking rate to cover high overhead. Avg. Stocking Rate Time (years)

8 Conclusions from Early Years: 1)Grazing Systems do not mitigate overstocking. 2) Economic review works.

9 ADAPTATION #1 Action: Change to Ecological management paradigm (mental model) Goal: Improve secondary production through ecological health (Hypothesis) Mechanism: Unknown

10 The move to an ecological focus was driven by a failed grazing system All private managers are adaptive but not necessarily with an ecological paradigm

11 2000 Ecological Appraisal: )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 Mesquiteonly specific locations Green Needle not observed

12 ADAPTATION #2: Action: Decrease Stocking Rate ( ) Goal: Improved water cycle Mechanism: 1. Improved animal performance from decreased competition for forage 2. Increased residuals cause improved water capture and infiltration

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14 Stocking Rate (AUD/ha) Annual Precipitation (cm) Cattle Percent Return on Investment (ROI) Deferral Length (days) Economic, Grazing, and Precipitation Data: Overstocked Management Paradigm: Ecological Process-based Grazing Adaptation Avg. Precip. Avg. Stocking Rate ROI Cattle Avg. Precip. Avg. Stocking Rate Avg. Precip. Reduced stocking to Avg. Stocking Rate improve animal performance and water cycle Length of Deferral Time (years)

15 Adaptation #3 Cross fence to increase stock density ( ) 1. Ecological goal = Improved mineral cycle 2. Ecological process intervention = space/time density of manure and urine

16 No change in spatial manure density 2. Minimal recovery of flagged defoliated plants (Ungrazed period versus recovery period)

17 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

18 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

19 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 day recovery Most grazing studies were May or June to Oct. grazing They missed most cool season consumption.

20 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.

21 Strategy: Defer to allow reproduction: Increase Deferral to minimum 100 Days 9 Pastures to 36 Pastures 36 pastures allowed 100-day recovery with reasonably short graze periods. (Recall 3cm/week)

22 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)

23 Corollary #2: Animal selection matters Corollary #3: Seasonality matters Corollary #4: Variable stocking rates help (mix cow-calf, yearling, custom graze) Monitoring Data:

24 Jan April Nov % Plants Defoliated in a Graze Period (Averaged by Month 2010) ADAPTATION #2: SEASONAL DEFOLIATION PATTERNS 90 Western Wheat Blue Gramma Month

25 March 19, 2008 Early March defoliation 2007 Fall/Dormant defoliation 2007 (120 days deferral)

26 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.

27 Continuous grazing at moderate stocking allows adequate deferral of plants. Deferral occurs because 50% of the plants remain undefoliated. What about diversity and animal selection?

28 Jan April Nov % Plants Defoliated in a Graze Period (Averaged by Month 2010) Species Abundance Threshold Squirrel Tail Winterfat Blue Gramma Western Wheat Month

29 April, 2008

30 October, 2008

31 Percent plants with Seed Production Pastures Grazed Before June 30, 2010 Pastures Grazed after June 30, 2010 Seed production data gathered Fall 2010.

32 Timing of 2007 grazing related to plant recruitment spring % Young (<7cm) Plants Fall Grazed Jan. Feb Grazed March April 2007 Grazed May June 2007 Grazed July, Aug., Sept. 2007

33 Management can prepare for weather events: But palatability is a function of abundance San Louis Valley and 4 Wing Salt Bush

34 Economic Response of Process Based Adaptations?

35 Stocking Rate (AUD/ha) Annual Precipitation (cm) Cattle % Return on Investment (ROI) Economic, Grazing, and Precipitation Data: Overstocked Process-based Grazing Adaptation Avg. Precip. Avg. Stocking Rate ROI Cattle Length of Deferral Avg. Precip. Avg. Stocking Rate Avg. Precip. Avg. Stocking Rate Deferral Length (days) YEAR

36 Did we Achieve the Ecological Goal?

37 % Western Wheat >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)

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39 Typical Winterfat occurrence late 1990 s

40 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

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42 Reversible State-transition: Blue Gramma + Filaree +- Western Wheat Silver Bluestem Side Oats Vine Mesquite Green Needle Gr Western Wheat Blue Gramma

43 Conclusions from Case Study 1) A Grazing System was Ineffective: Grazing systems are a simple solution to a complex problem 2) Process based scientifically sound adaptations were effective: Recovery based on plant physiology to allow reproduction Varying defoliation patterns through seasonal grazing AND

44 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)

45 Hypothesis from Case Study 1) Species diversity varies positively with economic return. Ecological health can drive secondary production. (See Jacobo et al and Kothman et al 1971) 2) Length of deferral vs. diversity is complex:

46 Variable Y Definition of Complexity Inflection related to a change of underlying processes Complexity = Multiple relationships between variables Variable X

47 Species Diversity Length of Deferral vs. Species Diversity Inflection related to reproduction processes short duration grazing Complexity = Multiple relationships between variables 100 Days 1 Year Length of Deferral

48 % Studies Rotation > Continuous % of 24 Studies with Diversity Data 70% 60% 50% 40% 30% 20% 10% 0% Studies with Rest Periods > 89 Days (13) Studies with rest periods < 90 Days (11)

49 % Studies Rotation > Continuous 120% % of 24 Studies with Diversity Data 100% 80% 60% 40% 20% 0% Initial Seral State Low (6) Initial Seral State High (10) Initial Seral State Unknown (8)

50 Species Diversity Length of Deferral vs. Species Diversity High Initial Diversity History matters in complex systems Low Initial Diversity 100 Days 1 Year Length of Recovery

51 Species Diversity Length of Deferral vs. Species Diversity short duration grazing Inflection related to reproduction processes Rotation vs Continuous trials are not processbased quantitative science (Provenza 1991). continuous grazing 100 Days 1 Year Length of Recovery

52 Conclusion: Seasonality and return interval are important grazing variables. Complex problems require: 1)Process based science 2)Adaptive management 3)Effective communication between science and management (Boyd and Svejcar 2009) We pay lip service to complexity but we ignore it in the rotational grazing controversy.