Rangeland Management Before, During, and After Drought

Larry D. HoweryLarry D. HoweryRangeland & Forest Resources ProgramRangeland & Forest Resources ProgramSchool of Renewable Natural ResourcesSchool of Renewable Natural Resources

The University of Arizona, TucsonThe University of Arizona, Tucson

Road Map

Drought DefinedDrought Defined General Information on Drought General Information on Drought

Management Management Grazing Management Before DroughtGrazing Management Before Drought Grazing Management During DroughtGrazing Management During Drought Grazing Management After DroughtGrazing Management After Drought SummarySummary

Drought Defined

“…“…prolonged dry weather when prolonged dry weather when precipitation is less than 75% of precipitation is less than 75% of the average amount.”the average amount.” (SRM 1989) (SRM 1989) – Using this definition, drought – Using this definition, drought occurred from 1944-1984 in:occurred from 1944-1984 in:

13% of the years in the northwestern US 13% of the years in the northwestern US 21% of the years in the northern great plains 21% of the years in the northern great plains 27% of the years in the southern great plains 27% of the years in the southern great plains 43% of the years in the43% of the years in the southwestern USsouthwestern US

0123456789

101112131415161718192021

1890 1918 1927 1936 1945 1954 1963 1972 1981 1990

average drought----------------

Drought Defined

Precipitation Data (inches) for Precipitation Data (inches) for Springerville, AZ, 1890-1997Springerville, AZ, 1890-1997

General Information on Drought Management

Drought negatively affects individual plants Drought negatively affects individual plants and therefore forage production (Plants get and therefore forage production (Plants get thirsty and hungry during drought!)thirsty and hungry during drought!)

Above ground responseAbove ground response

Below ground responseBelow ground response

Livestock managers use domestic livestock to Livestock managers use domestic livestock to market forage production on rangelandsmarket forage production on rangelands

General Information on Drought Management (cont.)

Range condition can limit Range condition can limit or accelerate drought or accelerate drought impacts – rangeland in impacts – rangeland in good condition:good condition:

Is less adversely affected Is less adversely affected by droughtby drought

Recovers faster after Recovers faster after drought breaksdrought breaks

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General Information on Drought Management (cont.)

Range condition going into drought is Range condition going into drought is importantimportant

General Information on Drought Management (cont.)

Intensity of grazing can limit or accelerate Intensity of grazing can limit or accelerate drought impactsdrought impacts

General Information on Drought Management (cont.)

20-25%soil saturated

10-12% 8-10%

6-8%

properly grazed overgrazed

Information taken from NRCS

ungrazed

Grazing can limit the ability of plants Grazing can limit the ability of plants to extract soil moistureto extract soil moisture

2-4%

General Information on Drought Management (cont.)

properly grazed overgrazed

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4”4”

2”2”

Timing of grazing can be importantTiming of grazing can be important

Grazing Management Before Drought

EffectiveEffective stocking rate is important stocking rate is important

Implement a grazing system that Implement a grazing system that promotes stable or improved range promotes stable or improved range condition via periodic deferment or rest to condition via periodic deferment or rest to establish forage reservesestablish forage reserves

Adequate plant cover and residual Adequate plant cover and residual vegetation are importantvegetation are important

Drought management needs to be considered on a case-by-case basis

Grazing Management Before Drought (cont.)

Depth of water penetration 5 days after 2.5 inches of rain on a 10% slope

Information taken from NRCS

Adequate ground cover increases moisture infiltration and percolation

Grazing Management Before Drought

Increase infiltration and percolationIncrease infiltration and percolation

Protect soil from wind and water erosionProtect soil from wind and water erosion

Decrease evaporation & transpiration lossesDecrease evaporation & transpiration losses

Provide a more favorable micro-climate for Provide a more favorable micro-climate for seedling establishmentseedling establishment

Adequate ground cover helps to:Adequate ground cover helps to:

Grazing Management During Drought

Continue to maintain range Continue to maintain range condition and plant vigor condition and plant vigor to the extent possibleto the extent possible

Monitor the use of “key Monitor the use of “key forage species” and other forage species” and other forage resources (browse, forage resources (browse, annuals, other ephemerals)annuals, other ephemerals)

Keep livestock distributedKeep livestock distributed

Develop an annual, Develop an annual, flexibleflexibletimetable for making decisionstimetable for making decisions

Grazing Management During Drought (cont.)

Provide adequate, accessible, Provide adequate, accessible, good-quality watergood-quality water

Once drought is recognized, reduce the herd as soon as possible so it is in balance with forage supply

Use emergency forage

Determine the amount of money that can be spent on animal feed and supplements

Grazing Management After Drought

Rest pastures for an entire growing season

Use pastures only when key forage species are dormant and when the least desirable species are green and palatable

Restock slowly and conservativelyRestock slowly and conservativelyon a case-by-case basison a case-by-case basis

Grazing Management After Drought (cont.)

Defer grazing until after key forage species have produced mature seed

Graze spring growth after grasses have reached the 4 to 5 leaf stage

SUMMARY Droughts are a guaranteed but unpredictable Droughts are a guaranteed but unpredictable

occurrence in the arid western U. S.occurrence in the arid western U. S.

Droughts are “normal” so advance planning is Droughts are “normal” so advance planning is critical critical before drought occursbefore drought occurs

During drought, delays in decision-making can lead During drought, delays in decision-making can lead to intensification of the problem, economic loss, to intensification of the problem, economic loss, and long-term damage to rangeland resourcesand long-term damage to rangeland resources

After drought breaks, restock slowly and After drought breaks, restock slowly and conservatively on a case-by-case basisconservatively on a case-by-case basis