Lecture 8: Range Inventory And Monitoring Flashcards
Range Inventory
Systematic identification, mapping, and quantification of ecosystem biophysical components, and the human infrastructure needed to manage livestock
Rangeland monitoring
Evaluating the impact of grazing and browsing on a plant community to facilitate management changes. Can also be the interpretation of range inventory data
Which level does inventory occur at?
Occurs at the level of the landscape
What is included in an inventory?
- total area
- pasture size and fencing
- infrastructure, roads, buildings
- water, natural and artificial sources
- livestock and wildlife
- vegetation and soils
What does monitoring include?
- precipitation
- production
- plant community and ecosystem health
- grazing use
- animal production
- profits
- changes in wildlife populations
Mapping
Focuses on the vegetation present. Usually an aerial photo via GIS. From this we can classify vegetation broadly and estimate biomass
Vegetation
What types of plant communities are present? This includes spices composition and abundance. Plant classification includes community types and their associations. For site selection, we assume it is representative, and that if we manage for the sensitive areas, adequate management will be ensured at all areas.
Vegetation cover and density
Two different types of data
- density has to do with spatial arrangement, and how close they are.
- cover has to do with the actual biomass
Frequency
The proportion of fixed area plots with a given plant species. This is easy to measure, but is not good for management
Height
A crude indicator of plant vigorous. It is often used to assess habitat quality
Biomass production/productivity
The ANPP is the annual net primary production. This is the total new plant growth in a growing season
Herbage
Total plant biomass of all grasses and Forbes at one point in time
Forage
Total plant biomass that is acceptable for animal consumption
Browse
Leaves and twigs of shrubs and trees that are available and acceptable for animal consumption
Utilization
The amount of production removed by herbivores
Forage quality
This is the crude protein and the acid digestible fibre
Inventory data collection methods depend on
Cost, time, personnel, data needs, and variability
Infrastructure: pasture
Land areas exposed to herbivores at one point in time. Limits are usually fenced, includes the number and size of pastures, and the distribution of location, elevation, and topography
Infrastructure: fencing
Perimeter vs. Cross fencing, permanent or electric, and game proof or cattle proof
Infrastructure: water
Number of sources, location, distribution, type, and quality of water
Stages of grazing induced retrogression
- Reduction in vegetation stature/ height
- Decline in herbivore preferred plant species
- Replacement of preferred species with avoided and/ or grazing tolerant species
- Loss of litter, soil xerification
- Further composition shifts from mesic to xeric adapted species
- Extensive litter loss, leading to accelerated erosion, loss of OM, and decline in soil quality
Plant responses to grazing
Decreasers: decline in abundance under any grazing
Increasers: peak abundance under light to moderate grazing
Trend
The direction of change in range condition, used traditionally to describe conditions for livestock.
Linear retrogression model
Assumes response to grazing is predictable and reversible
Advantages of linear models
Simple to use, easy to identify management implications and it works well where rangeland resilience is high and where a distinct climax is apparent
Problems with linear model
In many areas, climax is unknown, unrealistic to manage for, and may not be the most desirable community (max diversity at intermediate disturbance). Linear models work poorly in some systems and are ineffective in semi-arid areas with long unpredictable response times
Problems with the use of enclosures and benchmarks
Eliminating grazing is unnatural, and causes stagnation, and a reduce in production and diversity. Exclosures can also be small and isolated, making it hard to extrapolate to coarser scales. They can trap snow, attract birds and rodents. The starting range conditions are often poor. Ungrazed remnants are limited to lower quality range sites
Non linear retrogression model
Grazing response is not linearly reversible due to physical alteration of the environment, or complex vegetation responses. There is a threshold between states
Calculation of range condition
Condition is determined by comparing the abundance of plant species in the current community with the ungrazed state that may be expected for a given range site
Ungrazed state is…
- Climax: stable native community formed in the absence of grazing, with no introduced species
- Benchmarks: areas protected from grazing, via human made fenced enclosures, or natural islands
- PNC: potential natural community, one that includes naturalized plants. Suggests that the climax state may not be the best
Range trend
Actual quantified changes in condition rating over time, at last 2 separate measurements
Apparent trend
This is the inferred trend based on a single assessment, using indicators. Indicators are the characteristics that provide meaningful information for interpreting levels of animal use, range condition, trend, etc.
Range health
The ability of current vegetation to maintain long-term productivity and ecological integrity for a given state
Multiple stable states
Occurrence of several stable communities for a particular range site, each separated by distinct ecological thresholds
State and transition models
Relate alternative stable states to one another based on environment and disturbances. This shows the dangers of improper management, and h opportunities available to enhance management
Riparian health
Channel sinuosity and bank profile stability based on steam profile and vegetation composition, and a host of other ecosystem functions
Site composition threshold
Minimum plant cover and litter needed to prevent accelerated erosion
