![5022](https://edit.jornada.nmsu.edu/uploads/large/es/pc/5022.jpg)
Loamy
Scenario model
Current ecosystem state
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Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
Heavy continuous grazing
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Transition T1B
Heavy continuous grazing, non-use, no fire, invasion
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Transition T1C
Conifer invasion, no fire
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Transition T1D
Tillage
More details - Transition T2a More details
- Transition T2b More details
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Transition T2A
Tillage
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Transition T3A & T3B
Non-use, no fire, heavy continuous grazing
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Transition T3C
Tillage
More details - Restoration pathway R4 More details
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Restoration pathway T4A
Long term prescribed grazing, prescribed burning
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Transition T4C
Conifer invasion, no fire
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Transition T4B
Tillage
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Restoration pathway T5A
Brush management, prescribed burning
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Restoration pathway T5B & T5D
Brush management, prescribed burning
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Transition T5E
Brush management, tillage
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Restoration pathway T6A
Seeding
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Restoration pathway T6B & T6C
Seeding, cropped and abandoned
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
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Description
The Loamy site occurs on upland areas. Soils are well drained and have less than 40 percent clay in the surface and/or subsoil. The surface and subsoil textures typically are loam, silt loam, silty clay loam, clay loam, sandy clay loam, and very fine sandy loam. Some soils are underlain with sand or gravel at about two to three feet in depth. In some areas the surface layer may consist of stony to extremely stony. The central concept soil series are Agar, Glenham, and Highmore, but other series are included. This state represents the natural range of variability that dominated the dynamics of this ecological site (ES). This state was dominated by cool-season grasses, with warm-season grasses being subdominant. In pre-European times, the primary disturbance mechanisms for this site in the reference condition included periods of below and above average precipitation, periodic fire, and herbivory by insects and large ungulates. Timing of fires and herbivory coupled with weather events dictated the dynamics that occurred within the natural range of variability. In some locations, this site likely received relatively heavy grazing pressure. Cool-season and taller warm-season grasses would have declined and short warm-season grasses would have increased. Today, a similar state, the Native/Invaded State (State 3) can be found on areas that are properly managed with grazing or prescribed burning and sometimes on areas receiving occasional short periods of rest. These sites are differentiated by the presence of exotic species such as Kentucky bluegrass and smooth bromegrass. On most Loamy ESs within this MLRA, these species have invaded and are now present. It is likely that attaining the reference state as it is described here (without the presence of exotic herbaceous species) is not possible.
Submodel
Description
This state is the result of heavy continuous grazing, and in the absence of periodic fire due to fire suppression. This state is dominated by blue grama and buffalograss forming a dense sod layer that effectively blocks introduction of other plants into the system. Taller cool-season species will decline and a corresponding increase in short statured grass will occur. Low growth forms and low and late growing points allow blue grama, buffalograss, and upland sedges to tolerate and sometimes avoid heavy continuous grazing. This state has a high level of resiliency and changes occur very slowly with a long-term prescribed grazing. Once the threshold is crossed, a change in grazing management alone cannot cause a reduction in the sod grass dominance.
Submodel
Description
This state represents the more common range of variability that exists with higher levels of grazing management but in the absence of periodic fire due to fire suppression and the presence of exotic species such a Kentucky bluegrass and smooth bromegrass. This state is dominated by cool-season grasses. It can be found on areas that are properly managed with grazing or prescribed burning, and sometimes on areas receiving occasional short periods of rest. Taller warm-season species can decline and a corresponding increase in short statured grass will occur.
Submodel
Description
This state is a result of encroachment mainly by invasion and dominance of introduced cool-season grasses. This state is characterized by the dominance of smooth bromegrass, crested wheatgrass, and Kentucky bluegrass, and an increasing thatch layer that effectively blocks introduction of other plants into the system. Plant litter accumulation tends to favor the more shade tolerant introduced grass species. The nutrient cycle is also impaired, and the result is typically a higher level of nitrogen which also favors the introduced species. Increasing plant litter decreases the amount of sunlight reaching plant crowns thereby shifting competitive advantage to shade tolerant introduced grass species. The ecological processes are not functioning, especially the biotic processes and the hydrologic functions. The introduced cool-season grasses cause reduced infiltration and increased runoff. Preliminary studies would tend to indicate this threshold may exist when Kentucky bluegrass exceeds 30 percent of the plant community and native grasses represent less than 40 percent of the plant community composition. The opportunity for high intensity spring burns is severely reduced by early green up and increased moisture and humidity at the soil surface and grazing pressure cannot cause a reduction in sodgrass dominance. Production is limited to the sod forming species. Infiltration continues to decrease and runoff increases and energy capture into the system is restricted to early season low producing species. Nutrient cycling is limited by root depth of the dominant species.
Submodel
Description
This state is dominated (canopy exceeds 20 percent of total surface area) by areas where trees have become established or have encroached onto the site due to the absence of periodic fire. This state is dominated by eastern redcedar or Rocky Mountain juniper with cool-season grasses being subdominant. The plant community can develop into a closed canopy that impedes the reproductive capability of the major native perennial grass species. A single eastern red cedar tree with a 7 foot crown diameter eliminates the equivalent of 3 pounds of forage. Further, the forage potential of a pasture with 250 mature eastern red cedar trees per acre (or one tree every thirteen feet) is reduce by 50 percent. It is suggested that reducing stocking rates by 10 percent for every 50 trees per acre. The increase in tree canopy which is a result of a disruption of the natural, and human related fire regimes that occurred prior to European settlement, which kept trees from encroaching much of the grasslands.
Submodel
Description
This state is characterized by the production of annual crops using a variety of tillage and cropping systems along with management practices. Cropping on this site is enabled during years with drier than normal precipitation or with artificial drainage (surface or subsurface).
Submodel
Mechanism
Heavy continuous grazing (stocking levels well above carrying capacity for extended portions of the growing season, and often at the same time of year each year, typically beginning early in the season) will likely lead this state over a threshold resulting in the Short Grass Sod State (State 2).
Mechanism
Non-use or no surface fire for extended periods of time (typically for 10 or more years) causing litter levels to become high enough to reduce native grass vigor, diversity, and density, or heavy continuous grazing or invasion of non-native plant species will likely lead this state over a threshold resulting in the Native-Invaded State (State 3).
Mechanism
No surface fire for extended periods of time (typically for 10 or more years) causing litter levels to become high enough to reduce native grass vigor, diversity, and density, and invasion of conifer will likely lead this state over a threshold leading to the 5.1 Eastern Red Cedar-Rocky Mountain Juniper/Western Wheatgrass-Blue Grama Plant Community Phase within the Conifer/Invaded State (State 5).
Mechanism
Tillage will cause a shift over a threshold leading to the 6.1 Annual Crops Plant Community Phase within the Crop Production State (State 6).
Mechanism
Heavy Continuous Seasonal Grazing with stocking levels well above carrying capacity for extended portions of the growing season, and at the same time of year, each year, or Heavy Continuous Season-Long Grazing with stocking levels well above carrying capacity utilizing available forage through the majority of the growing season in the absence of adequate rest periods, and grazing at the same period each year will shift this plant community to the 3.1 Blue Grama/Buffalograss Sod Plant Community Phase within the 3.0 Degraded State.
Mechanism
Non-Use and No Fire for extended periods of time (typically for 10 or more years) can lead this state over a threshold to the 4.0 Invaded State. Heavy continuous Seasonal Grazing at the same time of year, each year, without adequate recovery periods or chronic heavy grazing will also result in crossing this threshold.
Mechanism
Tillage will cause a shift over a threshold leading to the 6.1 Annual Crops Plant Community Phase within the Crop Production State (State 6).
Mechanism
T3A - Non-use or no surface fire for extended periods of time (typically for 10 or more years) causing litter levels to become high enough to reduce native grass vigor, diversity, and density, will likely lead this state over a threshold leading to the 4.1 Smooth Bromegrass-Kentucky Bluegrass Community Phase within the Invaded State (State 4).
T3B – Heavy continuous grazing (stocking levels well above carrying capacity for extended portions of the growing season and often at the same time of year each year), will likely lead this state over a threshold leading to the 4.2 Kentucky Bluegrass-Blue Grama Community Phase within the Invaded State (State 4). Grazing repeatedly in the early growing season can expedite this shift by causing mechanical disturbance due to trampling.
Mechanism
Tillage will cause a shift over a threshold leading to the 6.1 Annual Crops Plant Community Phase within the Crop Production State (State 6).
Mechanism
Prescribed Fire occurring at relatively frequent intervals and occasional grazing events immediately following early season fire will cause a reduction in cool-season grasses such as Kentucky bluegrass and smooth brome and an increase in warm-season and later growing cool-season grasses. Warm-season grasses are more tolerant of short fire return intervals. Fire will temporarily increase the vigor and production of warm-season grasses and many native cool-season grasses when fire is timed properly. Pest management using chemical or mechanical treatment to suppress invasive cool-season grasses may also be required. This results in a shift to the 2.0 Native/Invaded Grass State. This would also require Long-Term Management with Prescribed Grazing (periodic light to moderate grazing with possible periodic rest). This may take up to 10 years or more, and recovery may not be attainable.
Relevant conservation practices
Practice | External resources |
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Prescribed Burning |
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Prescribed Grazing |
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Integrated Pest Management (IPM) |
Mechanism
Long-term prescribed grazing (moderate stocking levels coupled with adequate recovery periods, or other grazing systems such as high-density, low-frequency intended to treat specific species dominance, or periodic light to moderate stocking levels possibly including periodic rest) coupled with prescribed burning occurring at relatively frequent intervals (3 to 5 years) and a return to normal disturbance regime levels may lead this plant community phase over a threshold to the Native/Invaded State (State 3).
Mechanism
No surface fire for extended periods of time (typically for 10 or more years) causing litter levels to become high enough to reduce native grass vigor, diversity, and density, and invasion of conifer will likely lead this state over a threshold leading to the 5.2 Eastern Red Cedar-Rocky Mountain Juniper/Kentucky Bluegrass Plant Community Phase within the Conifer/Invaded State (State 5).
Mechanism
Tillage will cause a shift over a threshold leading to the 6.1 Annual Crops Community Phase within the Crop Production State (State 6).
Mechanism
Brush management which would include the mechanical removal of the conifers, coupled with prescribed burning occurring at relatively frequent intervals (3 to 5 years) and a return to normal disturbance regime levels may lead this 5.1 Eastern Red Cedar-Rocky Mountain Juniper/Western Wheatgrass-Blue Grama Plant Community Phase within the Conifer/Invaded State (State 5) over a threshold to the Reference State (State 1).
Mechanism
T5B – Brush management which would include the mechanical removal of the conifers, coupled with prescribed burning occurring at relatively frequent intervals (3 to 5 years) and a return to normal disturbance regime levels may lead this 5.2 Eastern Red Cedar-Rocky Mountain Juniper/Kentucky Bluegrass Plant Community Phase within the Conifer/Invaded State (State 5) over a threshold to the Native/Invaded State (State 3).
T5D – Brush management which would include the mechanical removal of the conifers, coupled with prescribed burning occurring at relatively frequent intervals (3 to 5 years) and a return to normal disturbance regime levels may lead this 5.3 Eastern Red Cedar-Rocky Mountain Juniper Plant Community Phase within the Conifer/Invaded State (State 5) over a threshold to the Native/Invaded State (State 3).
Mechanism
Brush management which would include the mechanical removal of the conifers, coupled with tillage will cause a shift over a threshold leading to the 6.1 Annual Crops Plant Community Phase within the Crop Production State (State 6).
Mechanism
Seeding may lead this Crop Production State (State 6) over a threshold to the Native/Invaded State (State 3).
Mechanism
T6B – Seeding may lead this Crop Production State (State 6) over a threshold to the Invaded State (State 4)
T6C – Cropping followed by abandonment may lead this plant community phase over a threshold to the Invaded State (State 4) and more specifically to the 4.3 Annual Pioneer-Perennial Pioneer Plant Community Phase.
Model keys
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The Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.