1. General Model Information

Name: Simulating Production and Utilization of Range Land

Acronym: SPUR

Contact:

Author(s):

Abstract:

SPUR (Simulating Production and Utilization of Range Land) is a simulation and process model. Its purpose is to determine and analyze management scenarios as they affect rangeland sustainability and to forecast the effects of climate change on rangelands. ELM , BLUE GRAMA and ROOTS were studied extensively during the construction of this plant growth model.

The model is unique because :

• it is a multipoint model,
• it is designed to allow for direct competition between several species for water and nitrogen, and
• the model has incorporated the impacts of wild and domestic herbivores.

Aboveground processes simulated in the SPUR model:

• Photosynthesis (soil water, nutrient, phenology or leaf age, temperature, solar radiation, leaf water potential)
• Carbon allocation (variable allocation to leaf area ratio, soil water, nutrient, phenology or leaf age, temperature)
• Death (leaf area, soil water, temperature, phenology or leaf age, trampling)
• Germination (soil water, temperature).

• Carbon allocation (fixed allocation)
• Root growth (soil water, soil nutrient, root to shoot ratio)
• Death (soil water, soil temperature)
• Uptake (soil nutrient)
• Respiration (soil temperature).

SPUR I contains four components:

1. hydrology;
2. plant growth;
3. animal physiology and harvesting (for both domestic and wildlife); and
4. economics.

Driving variables for the model include daily precipitation, maximum and minimum temperature, solar radiation and wind speeds. SPUR I has been validated by several researchers (Hanson et al., 1992a).

SPUR II:
SPUR2 DOS ver. 2.2 is a general grassland ecosystem simulation model designed to determine beef cattle performance and production by simultaneously simulating production of up to 15 plant species on 36 heterogeneous grassland sites. SPUR2 simulates grassland hydrology, nitrogen cycling, and soil organic matter on grazed ecosystems as well as rangeland production under different climatic regimes, environmental conditions, and management alternatives.
Limitations:

• Annual grasses are not simulated.
• The model requires fairly detailed parameterization when new plant species are added to the system
• CBCPM (Colorado Beef Cattle Production Model) is a very detailed genetic model and may be to complex for many of the range management questions under consideration
• The erosion and runoff routines used in SPUR2 many not be valid under all rangeland conditions.

• Incorporate the CENTURY Soil Organic Matter Model into the SPUR2 framework
• Develop and incorporate a grassland burning management option
• Improve the hydrology components of the model
• Update and improve the user interface
• Build SPUR2 into the GRASS Geographic Information System
• SPUR-2000: Decision Support System for Assessing and Managing Rangelands

II. Technical Information

II.1 Executables:

II.2 Source-code:

II.3 Manuals:

II.4 Data:

III. Mathematical Information

III.1 Mathematics

III.2 Quantities

III.2.1 Input

III.2.2 Output

IV. References