March 30, 2012
Page 1 of 4
What is a drought?
Drought is a normal part of the climate fluctuation
cycle and can affect all rangelands - forests,
parkland, native grasslands, tame pastures and
riparian areas. Rangeland managers should
consider and include drought in their planning.
Drought can occur when precipitation in an area is
well below normal. The low moisture conditions
must be sustained over a period of time. A few
months of little or no precipitation is not necessarily
a drought, but can trigger one. Above average
temperatures or consistently high winds can
increase evaporation and exaggerate drought
conditions. Signs of drought include low soil
moisture reserves, no surface water and limited
vegetation growth.
Managers need to take prompt action when a
drought is experienced.
How does drought affect rangelands?
•
•
Lower forage production – forage will vary
based on rangeland health and plant
composition, but drought will reduce forage for
livestock and the forage value of available
growth could be less than normal, affecting herd
health.
Reduced litter - Litter is the old plant residue
that is left over from previous years production;
it can be standing, recently fallen or partially
decomposed material. Litter shades and cools
the soil reducing soil evaporation. It aids in
trapping snow, increases water infiltration and
reduces raindrop impact on the soil. When
mositure is scarce, rangelands with adequate
litter layers will produce more forage than those
with low to absent litter layers. If litter layers are
•
•
very low, as a result of previous heavy use, the
rangeland could experience a man-made
drought.
Water quality – quantity and quality of surface
water decreases.
Soil type – drought effects may be more
pronounced on rangelands with sandy soils
than on loams or clays.
Impacts of grazing during a drought
•
•
•
Grazing removes plant cover and plant litter,
further increasing the drying effect and
worsening drought conditions.
Individual plants that are already in a weakened
state may die.
Weeds will take advantage of the reduced
competition and spread.
Long-term effects of over-grazing during
a drought
•
•
•
•
•
The range can experience a long term loss of
plant cover, productivity and litter.
The composition of plant species can shift.
Water supplies take longer to replenish.
The effects of a drought can be felt over a
longer time frame.
The risk increases for more frequent or more
severe drought in the future.
Managing rangelands during a drought
The principles for drought management remain the
same for all rangelands – forests, parkland, native
grasslands, tame pastures and riparian areas;
however the management strategy that should be
employed will depend on rangeland health before a
drought.
If litter levels are low when a drought occurs,
production will be significantly reduced and the
recovery period will be longer. If litter levels are
allowed to increase, through reduced grazing or
periods of rest, production will increase and the
time required to recover from subsequent droughts
will decrease.
March 30, 2012
Page 2 of 4
Healthy range
Plants are healthy and there is ample litter. Roots are able to reach soil moisture and nutrients. Forage
production is decreased, but not as dramatically as ranges in lower condition.
Management: Reduce stocking rate to match lower forage production and preserve the litter layer.
Recovery will be quicker if plants are healthier and better able to withstand drought stress.
Healthy with problems range
Litter is patchy, bare soil is visible, and plant health and productivity has declined.
Management: Reduce the stocking rate for several years after the return to normal precipitation to
rebuild litter reserves, ground cover and plant vigour.
Unhealthy range
There is little to no litter or carryover. Plants are short and weak with shallow roots. Forage production
has declined, weedy species have increased and bare ground is prominent.
Management: Multiple years of rest and careful management are required to restore rangeland health.
March 30, 2012
Page 3 of 4
Additional options during drought conditions
•
•
•
•
•
Evaluate and adjust herd composition and numbers so that
stocking rates match forage production and ensure appropriate
carryover to help maintain litter.
Secure sources of supplemental feed—additional pasture, hay,
failed crops.
Where appropriate, seed a drought tolerant, quick growing cereal
such as fall rye for emergency grazing.
Provide rest or defer grazing on lands in an unhealthy condition
to avoid further stressing the plants.
Use herding, fencing, salt placement and water
sources to improve distribution over the whole
range to prevent overgrazing of sensitive or
unhealthy areas.
Stockpile sufficient feed supplies during years of
surplus to provide flexibility during drought. Include a
rest pasture in your grazing rotation to provide a
forage reserve during a drought. During dry
conditions, reduce the herd to essential and
productive animals to reduce the
demand for feed. Structure your herd
to include easily marketed animals,
such as yearlings, for flexibility.
Include drought in future
planning
Range managers should recognize
that drought is a normal occurrence,
integrate drought into operational
decisions, and develop management
plans to reduce drought impact on the
soil-plant-animal complex. Proper stocking rates, healthy plants and
sufficient carryover or litter will reduce the impacts of droughts.
Riparian areas provide
both forage and water
during a drought. As
preferred grazing areas
they need to be
managed carefully to
prevent overgrazing,
maintain vegetative
cover, prevent trampling
and soil erosion, and
conserve water quality.
Consider offsite
watering or point
access watering on a
critical watershed.
ISBN:
978-0-7785-9146-7 (Printed Version)
978-0-7785-9147-4 (Online Version)
Pub No. I/448
Printed June 2010
March 30, 2012
Page 4 of 4