Lecture 14: Multiple Use Management of Rangeland

Multiple Use Philosophy

-use of range for more than one desirable or beneficial purpose

-societal demands that public ranges be managed for “all legitimate uses”

-ranchers can increase income through multi-use=seldom maximum benefit for any single use

-examples of alternative income products=hunting privileges, wildlife viewing, horseback riding, lumber, ornamental plants

Importance of Residual Vegetation

-growing concerns with herbage residue

-aesthetic appearance is becoming an important management objective, especially on public lands=general public believes more standing forage and less fecal patties improves the value of rangelands, visual “quality” is not based on the plant population but the volume of standing biomass

-residual vegetation is important for=soil, watershed, livestock, and wildlife

-moderate stocking rates are necessary to ensure that rangeland agriculture is=ecologically sound, economically viable, socially acceptable

Hydrology

-water is the greatest limiting factor to plant production on most rangelands

-precipitation=3 fates=infiltration (movemment into soil, portion available for plant growth), surface runoff (moves laterally off of the site towards streams, ponds, oceans, etc), evaporation (returns to the atmosphere as water vapor)

-how much precipitation is lost to evaporation=around 70% of range precipitation is lost to evaporation

-rangelands are the primary source of water for arid/semi-arid west=household use, irrigation, industry

-range practices highly influence water quality and quantity

Influence of Range Management

-type and amount of vegetation significantly affects disposition of precipitation whether it infiltrates the soil or runs off=grazing management has a significant influence on vegetation characteristics

-all surface water is being perceived as for human use=increasing view of range as “water generator” for cities and irrigation, in the future range management may be geared towards water production rather than forage production

Hydrological Cycle

-solar energy results in=vaporization of water from the earth’s surface, condensation as a result of cooling, and returning to the earth as precipitation

-man can influence hydrological cycle by modification of vegetation and soil=this results in changes in the water yield and quality from rangeland

Runoff and Erosion

-surface runoff is initiated when precipitation rate exceeds infiltration rate (velocity=distance/time)=infiltration is influenced by vegetation and soil type

Mechanisms of Vegetation on Runoff and Erosion

-forces of erosion=splash effect (destructive forces of raindrops on bare ground), runoff (flow disturbance related to velocity, precipitation rate exceeds infiltration rate), wind (the force of air movement removes soil particles not protected by plant residue)

-plant material, whether dead or alive provides protection from these forces=increases infiltration rate, decreases runoff, decreases the destructive forces of wind, maintains soil character

Grazing Impacts on Watersheds

-livestock affect watersheds by consuming plant parts and treading on the ground

-results in=compaction of the soil, vegetation loss

-both of these increase the rate of soil erosion

-range erosion is measured by sediment yields in runoff

-grazing results in decreased vegetation, decreased water infiltration, and increased runoff

-increase of short duration grazing=significantly higher erosion than all other methods, due to vegetation loss and soil compaction

-mulch impact=increase in mulch results in decrease in soil temp and evaporation and an increase in infiltration and forage production, especially critical in arid areas (20% increase in infiltration=40-50% increase in forage), promotes soil-binding perennials

Surface Water and Grazing

-although riparian (streamside) zones comprise a small percentage of most rangelands, their health is extremely critical to fish and wildlife=uncontrolled grazing severely affects fish populations, heavy grazing widens the stream channel and destroys streamside vegetation

-overgrazing of riparian areas results in=higher sediment in the water, lower oxygen content, reduced cover for fish, higher water temperatures, lower food source

-elimination of grazing can lead to restoration of riparian areas

Timber Production and Grazing

-not a consistent balance=as trees mature, the canopy closes (prevents forage growth=no sunlight), young trees are especially sensitive to grazing impacts-need protection

-common problems=trampling, girdling, defoliation of seedlings

-benefits of grazing=grazing and browsing of shrubs decreases competition for tree seedlings

Recreational Use and Urbanization

-highly accelerating demand within past 20 years=about 50% increase of visitors to BLM lands

-required on many federal lands

-the sale of homesites has had the most severe impact of all recreational uses=especially in mountain valleys of the west, use the surrounding summer ranges for recreation which replaces livestock production

-impact of urbanization on rangeland=fewer native species (plant and animal), more invasive species, overall decrease in game animals (decrease in wildlife habitat), increase in land values

-scenic beauty=”in the eye of the beholder”, general public does not understand the need for effectively managing rangelands