Land use 1
Rangeland

Rangeland uses of Loamy Upland, 12-16" pz., are most commonly livestock grazing, wildlife management and recreation; environmental services are many. Natural disturbances are fire, weather events, natural climatic cycling, and wildlife.

State 1.1
Native Grass (Reference)

The Native Grass (Reference) State is characterized by the open grassland aspect, with a wide variety of native perennial grasses dominating the plant community.

Characteristics and indicators. Native perennial grass basal cover ≥ 0.5%, large shrub (mesquite) canopy <5%, and succulent canopy <3%.

State 1.2
Non-Native Grass

Non-native lovegrass basal cover is more than 1% within the plant community; native perennial grass basal cover is diminished. Large shrubs are scattered with less than 5% canopy cover. Fire may act to increase exotic lovegrass at the expense of native perennial grasses, but may allow native annual species a chance to make seed and persist in the seed-bank. Some soil compaction has occurred due to livestock traffic, but hydrologic relationships have not been impaired

Characteristics and indicators. Large shrub canopy <5%; succulent canopy <3%; Non-native perennial grass basal cover >1%; native perennial grass basal cover 0-5%

State 1.3
Large Shrub, Native Grass

The open aspect is interrupted by large shrubs. The perennial grass community is diminished in diversity and basal cover.

Characteristics and indicators. Large shrub canopy >5%, median fetch* <20”, native perennial grass basal cover 0.5%, NN p.grass basal cover <1%; succulents may or may not be dominant, see CPs. *Fetch is distance from a point in any direction to nearest perennial plant base

State 1.4
Large Shrub, Non-native Grass

Large shrubs and non-native lovegrasses are co-dominant. Native perennial grasses may remain intact, generally under large shrub canopies. Non-native perennial grasses include African lovegrasses (most commonly Lehmann and Cochise lovegrasses) and, at the low and high elevations of this LRU, bufflegrass and yellow bluestem, respectively. The large shrubs are resistant to fire mortality and burning will not affect their removal from the plant community. Repeated burning or heavy grazing negatively affects the perennial grasses and puts the site at risk of excessive soil erosion. In these areas, mechanical brush management will likely result in transitioning the site to State 2, with a loss of native grasses, both their productivity and diversity.

Characteristics and indicators. Large shrub canopy >5%, median fetch* <20”, NN p.grass basal cover >1%; succulent canopy fluctuates, see CPs. Native perennial grass basal cover 0-5%. *Fetch is distance from a point in any direction to nearest perennial plant base

State 1.5
Large Shrub

Mesquite and other large shrubs have increased and are dominant with canopies greater than 5%. Native and non-native annual forbs and grasses, both cool and warm season, dominate the under-story. Snakeweed and burroweed cycle with climate, but both remain important in the plant community. Native perennial grasses are largely gone, due to the interactions of drought, fire and continuous, heavy grazing. Areas located close to mountains usually have higher soil cover of cobbles and gravel, thus, exhibit inherent soil and site stability. Hydrologic relationships have changed to increase the amount of runoff. Loamy upland in this State is at risk to transition to State 6 (Large Shrub, Eroded).

Characteristics and indicators. Large shrub canopy >5%, Median Fetch* >20”, perennial grass basal cover <1%, no evidence of active, accelerated erosion *Fetch is distance from a point in any direction to nearest perennial plant base

State 1.6
Large Shrub, Eroded

The Large Shrub, Eroded State is very similar in structure to States 4 and 5 (mesquite dominated, half-shrub understory), however, the soil erosion threshold has been crossed; active, extreme soil loss (exposed argillic horizon, rills, pedestals, gullies) is occurring. Snakeweed and burroweed cycle with climate, but both remain important in the plant community. Native perennial grasses are largely gone, due to the interactions of drought, fire and continuous, heavy grazing. Remnant non-native lovegrasses may be present. Hydrologic relationships are permanently altered. Restoration practices can be applied to slow erosion rates and trap sediments; paired with prescribed grazing, non-native lovegrasses will colonize the site resulting in Plant Community 2.2, Cultivated Lehmann lovegrass Community.

Characteristics and indicators. Large shrub canopy >5%, Median Fetch* >20”, perennial grass basal cover <1%, active, accelerated erosion as indicted by water flow patterns, litter dams, and rills *Fetch is distance from a point in any direction to nearest perennial plant base

Transition T1A
State 1.1 to 1.2

Seed introduction and livestock grazing w/o native grass management or spontaneous flourish of Lehmann lovegrass establishing from unknown seed bank following fire/drought.

Transition T1B
State 1.1 to 1.3

Extended fire-free interval (removal of fire fuel) and community composition changes by heavy, repeated or yearlong livestock grazing.

Transition T2A
State 1.2 to 1.4

Extended fire-free interval (removal of fire fuel) and community composition changes by yearlong or heavy livestock grazing.

Restoration pathway R**
State 1.3 to 1.2

From any Loamy Upland State, restoration practices applied to remove large shrub dominance or arrest accelerated erosion result in non-native perennial grass (Lehmann lovegrass) dominance.

Transition T3A
State 1.3 to 1.4

Seed introduction and livestock grazing w/o native grass management.

Transition T4A
State 1.4 to 1.6

Yearlong, heavy grazing, fire suppression

Transition T5B
State 1.5 to 1.4

Seed introduction and livestock grazing w/o native grass management

Transition T5A
State 1.5 to 1.6

Yearlong, heavy grazing, fire suppression

Land use 2
Cropland

Cropland includes areas used for the production of adapted crops for harvest. Two subcategories of cropland are recognized: cultivated and non-cultivated. Cultivated cropland comprises land in row crops or close-grown crops and also other cultivated cropland, for example, hay land or pastureland that is in a rotation with row or close-grown crops. Non-cultivated cropland includes permanent hay land and horticultural cropland. In this MLRA-LRU, cultivated cropland is the more common category of use; all cropland is irrigated. Several row crops and close-grown crops are grown including cotton, corn, chili, and small grains. Hay land crops, alfalfa and bermudagrass, are rotated on a 3-5 year cycle.

When cropping and irrigation are suspended, annual forbs and annual grasses will dominate the newly barren field. Common annuals first to come in include Russian thistle, careless weed, and brome. Over time, shrubs and sub-shrubs will establish, initially in low-lying areas and eventually may come to dominate. Native perennial grasses will be largely absent; bermudagrass patches may establish in low-lying areas. Farm field maintenance, periodic tillage, will sustain the barren field with annual forbs and grasses.

After farming, the site may be restored to an area suitable to a grazing use. However, long-lasting changes in soil structure, hydrology, and nutrient availability prevent the site from returning to the Rangeland State and Transition Model. Restoration practices may be implemented to attain achieve land use goals such as increased forage availability. A desired plant community that will persist without continued watering may seeded before cessation of irrigation.

Conversion C
Land use 1 to 2

Conversion from rangeland to cropland, requires extensive input into field and irrigation development.