State and transition model
State 1
1 Reference State
This is a grassland / shrub mix. The approximate total production breakdown is grasses are 60-70%, forbs 1-5%, shrubs 25-35% and trees 0-4%.
Western wheatgrass, squirreltail, muttongrass and blue grama are the dominant grasses and Wyoming big sagebrush is the dominant shrub.
Community 1.1
Reference Plant Community
The dominant aspect of the site is a grass-shrub mix. Major grasses include western wheatgrass, blue grama and bottlebrush squirreltail. Dominant shrubs are mountain and Wyoming big sagebrush.
Community 1.2
Increased Shrubs and Annuals (forbs and grasses)
Disturbance has reduced perennial grasses. Sagebrush, broom snakeweed, sixweeks fescue and annual lupine increase.
Pathway 1.1A
Community 1.1 to 1.2
Repetitive, high utilization of palatable grass species have given shrubs a competitive advantage.
Pathway 1.2A
Community 1.2 to 1.1
A disturbance such as fire to set the shrubs back along with management to improve palatable grass species.
State 2
2 Tree Invaded
Trees (mostly pinyon pine) is invading the site. Disturbed understory, lack of fire and favorable climatic conditions have opened up the site to this tree invasion. Left unchecked the trees and shrubs will dominate the site and the understory becomes less productive with less quality forage plant species. It takes tree and shrub treatments along with careful management which might include some re-seeding to move back to a more desired plant communty. There are times when drought and insect damage reduce tree densities,also. There may be very little to a few percent of non-native plants. Introduction of non-native annuals species creates an irreversible change in the plant community.
Community 2.1
Pinyon pine - Invaded Grassland/Shrub
This community will have pinyon pine (PIED) invade this site when fire has been suppressed and there is a favorable moisture regime to allow the trees to move in from adjacent areas. Grasses will still be the dominant plants followed by shrubs and will remain similar to the plant community of 1.1.
There may be very little to a few percent of non-native plants. Introduction of non-native annuals species creates an irreversible change in the plant community
Community 2.2
Tree/Shrubland
Continued tree invasion is facilitated by continuous understory disturbance. Pinyon pine and sagebrush expand and increase their influence on the site. Broom snakeweed and annual forbs and grasses increase while perennial native grasses decrease.
Note: Mechanical removal of the trees will be needed to reverse the tree invasion. There are times when drought, fire and insect damage reduce tree densities. There may be very little to a few percent of non-native plants. Introduction of non-native annuals species creates an irreversible change in the plant community
Pathway 2.1A
Community 2.1 to 2.2
Continued tree invasion is facilitated by continuous understory disturbance.
Pathway 2.2A
Community 2.2 to 2.1
Tree reduction
Transition T1A
State 1 to 2
Trees (mostly pinyon pine) is invading the site. Disturbed understory, lack of fire and favorable climatic conditions have opened up the site to this tree invasion. Left unchecked the trees and shrubs will dominate the site and the understory becomes less productive with less quality forage plant species.
Restoration pathway R2A
State 2 to 1
It takes tree and shrub treatments along with careful management which might include some re-seeding to move back to a more desired plant community.