Rangeland Management Before, During, and After Drought
Rangeland Management Before, During, and After Drought
Larry D. HoweryLarry D. Howery
Rangeland & Forest Resources ProgramRangeland & Forest Resources Program
School of Renewable Natural ResourcesSchool of Renewable Natural Resources
The University of Arizona, TucsonThe University of Arizona, Tucson
Road MapRoad 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 DefinedDrought 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
0
12
3
4
56
7
89
10
11
1213
14
1516
17
18
1920
21
1890 1918 1927 1936 1945 1954 1963 1972 1981 1990
average drought----------------
Drought DefinedDrought Defined
Precipitation Data (inches) for Precipitation Data (inches) for Springerville, AZ, 1890-1997Springerville, AZ, 1890-1997
General Information on Drought Management 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.)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.)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.)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.)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.)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 DroughtGrazing 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.)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 DroughtGrazing 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 Decrease evaporation & transpiration losseslosses
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 DroughtGrazing 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.)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 DroughtGrazing 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.)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
SUMMARYSUMMARY
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 During drought, delays in decision-making can lead to intensification of the problem, economic lead to intensification of the problem, economic loss, and long-term damage to rangeland loss, and long-term damage to rangeland resourcesresources
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