Drought Preparedness: Setting Critical Dates

Rangeland managers and livestock producers are typically optimistic, if we weren’t, we likely would not be in the business of agriculture. We believe things will improve and thus when drought is imminent or even occurring we sometimes wait too long to act. This results in a strain on resources both out on the range and in the pocketbook. Before we can respond to drought we need to come up with a plan on what we will do and tying that plan to critical dates is key for implementation.

In times of drought, some destocking of rangelands may need to occur.

In times of drought, some destocking of rangelands may need to occur.

 

In the high, cool season grass dominated plains of Wyoming where I live critical dates are tied to the amount and timing of precipitation we receive in the spring.  Grass growth in this area can be directly correlated to the amount of precipitation we receive in March, April, and May.  When developing a drought plan rangeland managers and livestock producers who graze on native rangelands should be monitoring precipitation amounts during these three months.

Grass growth during drought is stunted and peak standing forage is severely limited (Photo: Ashley Garrelts)

Grass growth during drought is stunted and peak standing forage is severely limited (Photo: Ashley Garrelts)

 

If March is dry, soil moisture will likely be limited.  Soil moisture is what drives the initiation of plant growth once temperatures reach optimum.  Cool season grasses typically start growth when soil temperature is 40-45 degrees F.  If soil moisture is inadequate, growth will be delayed, stunted, or nonexistent depending on future moisture events.  Thus the first critical date for a drought management plan is typically April 1.  At this time we have a good idea of what snow pack is in the mountains, what the soil moisture is, and we can start monitoring the 10 day forecasts to see what is headed our way. The month of April is critical.  Cool season grasses, which provide the bulk of our forage are growing and the correlation between moisture received and peak standing forage in July is high.  Therefore the second critical date is May 1.  This is where we need to start making some management decisions.  If moisture is below what is needed, then its likely time to start looking for other feed or pasture.  We may even need to do some destocking depending on the ranch and its resources.  The third and final critical date is June 1.  At this point the story has been told.  Temperatures are rising and cool season grass growth is slowing.  Moisture received in June on cool season dominated rangelands will do very little to influence peak standing forage.  If your ranch has a higher proportion of warm season grasses, June moisture will be more critical and your story may not be finished.  If moisture has not be adequate up to June 1 then management decisions must be made.  Most likely livestock numbers will need to be cut and additional forage purchased or leased.

Drought affected rangeland in June (Photo: Ashley Garrelts)

Drought affected rangeland in June (Photo: Ashley Garrelts)

 

Planning for drought is essential for livestock producers and range managers on all rangelands across the West.  In all actuality, drought is more common than wet years.  Being prepared and knowing what management decisions will be made during these tough times is essential for sustainability of all resources, including both the rangeland, and the pocketbook.

Timing and amount of precipitation is important to Wyoming's pastures (Photo: Ashley Garrelts)

Timing and amount of precipitation is important to Wyoming’s pastures (Photo: Ashley Garrelts)

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Prescription Grazing

Did you know that invasion by non-native, invasive plants is the one of the most dangerous threats to our ecosystems?  If you live and work in the open spaces of this country it is probably foremost in your mind, if you don’t, you are more likely to have heard how climate change is more of a threat through the popular media.  However invasive plants into the vast open spaces, such as rangelands and forest lands of the United States, likely play a bigger threat to the sustainability of these ecosystems.

Healthy, weed free, rangelands are key to maintaining wildlife habitat, ecological processes, and beautiful landscapes. (Photo: public domain)

Healthy, weed free, rangelands are key to maintaining wildlife habitat, ecological processes, and beautiful landscapes. (Photo: public domain)

 

On rangelands, invasive plants are what most people call weeds.  They are plants that spread naturally and many times aggressively.  They significantly alter the plant species present, water cycle, nutrient cycle, energy flow, and natural succession of a given plant community or ecosystem.  They are challenging to control due to the relatively low economic value and sheer remoteness of the land on which they occur.  Preventing these weeds from invading these lands is key to mitigating this threat; however what if weeds are already present?  The challenges that are faced when determining a method of weed control on these vast lands, may lead to managers choosing to use grazing livestock as a biological control for weed management.

Goats make excellent prescriptive grazers because of their love of weedy species. (Photo: public domain)

Goats make excellent prescriptive grazers because of their love of weedy species. (Photo: public domain)

 

Domestic livestock grazing is probably one of the earliest tools in vegetation management used by humans.  Today it has a new name and many researchers have been exploring ways to make prescriptive grazing a successful and economical way to control invasive weeds on rangelands.  Prescriptive grazing involves selecting the correct livestock and season, duration, and intensity of grazing for the specific weed that one is interested in controlling.  Proper management of grazing livestock is key when setting up any grazing plan whether it be tradition grazing of native species or prescriptive grazing of unwanted species.

Unwanted plants that are not controlled and are allowed to go to seed in the fall decrease the ability of native plants to compete for nutrients. (Photo: public domain)

Unwanted plants that are not controlled and are allowed to go to seed in the fall decrease the ability of native plants to compete for nutrients. (Photo: public domain)

 

The goal of prescriptive grazing is to manage defoliation of those unwanted plants in such a way that the native species are able to out compete the unwanted species for sunlight, nutrients, and water.  Two ways to do this are 1) to graze the targeted weed at the time and at a frequency and duration that is most detrimental to the plant and 2) to train livestock to graze primarily on the targeted weed.  For example leaf spurge (Euphorbia esula) is an invasive plant found on more than 5 million acres across 35 states and into Canada.  This weed can be controlled through the use of grazing sheep in such a fashion that 95% of the top growth is removed during the vegetative to flowering stage and regrowth is continually grazed to prevent flowering and seed production.  Grazing multiple times per year is needed in most cases and may need to be repeated for many consecutive years.  Combining grazing with herbicide will likely provide the most long-term control.  While this weed can be grazed by sheep and goats; the weed is poisonous to cattle and horses.  Once sheep or goats have been trained to eat leafy spurge they tend to prefer it over other vegetation due to its palatability and nutrient content.  However sheep do prefer younger plants while goats will eat the plant in all growth stages.

Sheep can be used to control weeds as well as other biological agents. (Stock Photo)

Sheep can be used to control weeds as well as other biological agents. (Photo: public domain)

 

The beauty of using domestic livestock as biological weed control is that not only are managers able to control unwanted plants but they are also able to then take that livestock and gain a salable product in the form of meat or fiber.  Just remember, prescriptive grazing is not a onetime shot, like many other forms of weed control it needs to be repeated and monitored for success.  However it may be a way that livestock and land managers can create and maintain healthy native rangelands all across the country.

Weed free rangelands provide habitat for all types of wildlife and domestic livestock. (Photo: public domain)

Weed free rangelands provide habitat for all types of wildlife and domestic livestock. (Photo: public domain)

 

Sources:  Prescribed Grazing for Rangeland Management  &  Targeted Grazing Handbook.

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