Grazing Management For Healthy Watersheds
Dr. M. Karl WoodDirector
Water Resources Research Institute
New Mexico State University
What is a healthy watershed?
Desired Functioning Condition?
What are the Goals?
Are the Goals Obtainable and Sustainable?
Watershed Goal?
ResourceExploitation
Sustainable Use
ResourceProtection
Exploitation Sustainable Protection
Use
Watershed Goal?
The extremes result in attitudes of supremacy
From: Thompson, P.B. 1995. The Spirit of the Soil - Agriculture and Environmental Ethics. Routledge Publ. New York, New York
New Mexico Historical PerspectiveWild Ungulates native to New Mexico
Cous deer
Mule deer
Whitetail deer
Pronghorn
Desert bighorn
Rocky Mountain bighorn
Elk
Bison
Javelina
Domestic and Wild Ungulates Introduced in last 500 years
Cattle
Swine
Sheep
Horses
Burros
Goats
Barbary sheep Oryx
Ibex
Grazing Effects on Plants
Land Management Practice
Plant and RockCover
Plant Volume
Animal Grazing, Trampling,and Burrowing
Soil Surface Roughness
Soil SurfaceConfiguration
Soil MoistureEvaporative
Loss
SoilOrganic Matter
Content
Soil Particle Sizes
Soil Structure
Soil Bulk Density and Porosity
Runoff andInfiltration
Grazing Effects on Plants
1. Grazing reduces plant cover and volume
Little Great StimulationResistance Resistance Response
2. Plants species respond differently to grazing
Antelope bitterbrushBlack grama Blue grama
Grazing Effects on Plants
2. Plants species respond differently to grazing continued…
Moderate to No GrazingBunchgrass
Heavy GrazingSodgrass
Blue grama Blue grama
Reduced Plant Cover and Plant Volume Effects the Watershed
1. Decreased interception and transpiration
3. Decreased water infiltration into soil surface
4. Increased runoff and erosion
2. Decreased organic matter additions to soil, which affect soil structure and porosity
5. Increased runoff and erosion lead to loss of sustainability after about 50% utilization of present year’s growth
Grazing Effects on Plants Continued…
Grazing can retard or stop invasion of salt cedar
Observed on:
1. Capitan Creek on the Pecos River
2. Middle Fork of the Gila River
3. Redstone Allotment of the Gila River
Trampling or Hoof Action Effects on Plants
1. Trampling reduces plant cover and volume.
2. Plant cover and volume reductions may:
a. Decrease Interception and Transpiration
b. Damage or kill the plants
c. Stimulate plant growth
Trampling or Hoof Action Effects on Soils
Trampling Effects on Soils
Soil Surface Runoff and Roughness Erosion
Wet Soil Dry Soil
Southwestern soils are usually dry!
Increases
Decreases
Decreases
Increases
Trampling Effects on Soil
Runoff and Trails Erosion
Up & Down Slopes
Across Slopes
Configuration
Increases
Decreases
Trampling Effects on Soil
Bulk Density Porosity Water Holding Runoff and Capacity Erosion
Bulk Density and Porosity
Bulk Density increases are usually mitigated with cold-weather freeze-and-thaw conditions.
Increases Decreases Increases Increases
Trampling Effects on Soils
When ungulates are removed
from watersheds, pocket gopher
populations often increase, even
exponentially.
Gopher mounds may add up to 5 tons/acre/yr of sediment into streams!
Trampling Effects on Soils
Gopher tunnels often lead to piping and eventually a side gully!A benefit of trampling is control of pocket gophers!
Animal Wastes and Nutrient Cycling
Soil Runoff and Erosion
Wind
Animal Wastes and Water Pollution
Fisheries in high fertility watersheds won’t benefit much from dung and urine additions but may suffer from over-enrichment.
Only that dung deposited on bare ground connected to a runoff system is expected to be eroded from a watershed.
Fisheries in watersheds of low fertility may benefit from accelerated erosion and elevated nutrient levels
Livestock and Wild Ungulate Management Strategies
Fences
It is easy to fence out livestock
It is difficult to fence out wildlife
Total number of ungulates may not change from fencing out livestock
Livestock and Wild Ungulate Management Strategies
Fences and exclosures may be problematic because they:
Lead to aesthetic considerations
Are expensive
Have annual maintenance hassles
Create problems with animal movement
Often result in unused forage
Livestock and Wild Ungulate Management Strategies
Stocking Rates
Extreme 100% Utilization - Rarely sustainableHeavy 75 “ - “ “ Moderate 50 “ - Usually sustainableLight 25 “ - “ “Exclusion 0 “ - “ “
Livestock and Wild Ungulate Management Strategies
Livestock and Wild Ungulate Management Strategies
Grazing systems
Grazing Systems – Example from Texas Rolling Plains
Stocking Infiltration Sediment System Rate Rate Production cm/hr kg/ha
Exclosure None
Deferred-Rotation Moderate
Continuous Moderate
Short Duration Moderate
Continuous HeavyWood and Blackburn. 1981. J Range Manage. 34:228-231; 331-335
11 b
14 b
28 ab
40 ab
114 a
15.2 a
13.9 ab
11.4 bc
8.2 c
8.1 c
Grazing Systems – Example from Fort Stanton, New Mexico
Stocking Infiltration Sediment System Rate Rate Production cm/hr kg/ha
Exclosure None
Continuous Moderate
Short Duration Heavy after resting
Short Duration Heavy after grazing
Continuous Heavy Weltz and Wood. 1986. JRM 39:365-368; J Soil & Water Cons. 41:262-266.
65 b
307 a
221 a
565 a
334 a
7.4 a
4.9 b
3.9 c
2.3 d
2.6 d
Grazing Systems – Example near Fort Sumner, New Mexico
Stocking Infiltration Sediment System Rate Rate Production cm/hr kg/ha
Exclosure None
Continuous Moderate
Short Duration Heavy after resting
Short Duration Heavy after grazing
Weltz and Wood. 1986. JRM 39:365-368; J Soil & Water Cons. 41: 262-266.
20 c
80 b
25 c
268 a
6.3 ab
5.5 b
7.0 a
3.8 c
Livestock and Wild Ungulate Management Strategies
Range Improvements
Plant Control
Biological
Burning
Herbicides
Mechanical
Livestock and Wild Ungulate Management Strategies
Range Improvements
Plant Enhancements
Seeding Fertilizing Waterspreading
Livestock and Wild Ungulate Management Strategies
Monitoring
Explore
Evaluate
Keep Records
Measure
Observe
ConclusionsFour noteworthy points can be made regarding the question: Can we graze watersheds?
4th If we don’t get our management act together, the public won’t let us graze watersheds because of high resource value and potential for damage from improper grazing!
1st Yes, we can graze these areas!
2nd We should be able to increase forage produced without damaging other uses!
3rd We don’t know yet how to do this in all areas!
If on the other hand the prime objective is watersheds, we should restore the grass, which all the evidence indicates is a better watershed cover than either brush or woodland.” Aldo Leopold
“If the prime objective is wood products, we may continue to overgraze, letting in the woodland and sacrificing watershed values.
A Good Quote
God Bless America!
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