State 1
Plant Community 2.3

Community 1.1
Plant Community 2.3

This community results from large flooding events. High volumes of water will rush through a stream system moving sediments and often uprooting vegetation. This community is primarily a mix of sands, gravels, and cobbles with either none or very little vegetative cover. Generally, in a healthy stream system, new vegetative growth soon sprouts, offering substantial root systems to stabilize the loose sediments.

Community Pathway 2.3a:
The shift from PC 2.3 back to PC 2.1 occurs after an extended period of time without disturbance from grazing or floods. Grasses, rushes and other forbs will regain dominance as root systems increase channel stability and available water. New cottonwood and willow will began to re-sprout if there is a seed source available.

Community Pathway 2.3b:
The shift from PC 2.3 back to PC 2.2 occurs after an extended period of time without disturbance from grazing or floods. In the absence of the native willow and cottonwood seedlings, mules-fat (Baccharis salicifolia) will often colonize first and become the primary shrub species. Grasses, rushes and other forbs will regain dominance as root systems increase channel stability and available water.

Transition 2
The transition to State 3 can take place under extreme grazing or flooding which puts stress on the community. Disturbances can hinder the growth of the new vegetation and may cause the barren river-wash seen in PC 2.3 to become a permanent, grassland state.

State 2
Historic State - Plant Community 1.1

Community 2.1
Historic State - Plant Community 1.1

The historic natural community for riparian areas on the Channel Islands was a mix of cottonwood (Populus spp.) and willow (Salix spp.), as well as an herbaceous cover of native grasses (Agrostis spp. and Eleocharis spp.), sedges (Carex spp.) and rushes (Juncus spp.). Before the introduction of grazing to the islands, there were likely dense stands of trees on a relatively flat, broad floodplain along the streams. However, heavy utilization for many years by domestic livestock and wildlife, due to their highly palatable nature, has caused a significant decline to complete removal in their cover (Wagner et. al).

Transition 1
Extensive grazing by livestock and non-native wildlife placed a stress on the historic state. This pressure gives an advantage to encroaching non-native plant species and will lead to the invasion of non-native annual grasslands.

State 3
Reference State - Plant Community 2.1

Community 3.1
Reference State - Plant Community 2.1

This state is similar to the historic plant community. There is a mix of cottonwoods and willows on the site, with an understory primarily dominated by non-native species such as oats (Avena spp.) and bromes (Bromus spp.).

Community Pathway 2.1a:
The shift from PC 2.1 to PC 2.2 occurs when widespread grazing by livestock and non-native wildlife remove the cottonwood and willow. This shift can also occur if there is a lack of flooding. Cottonwoods prefer bare sediment and may have difficulties regenerating along streams where flood events are not significant enough to create new sandbars. As the cottonwoods and willows disappear, so will their rooting systems that kept the water table high, offering water later into the growing season. Without these extensive roots, the water table begins to drop, leaving less water for new seedlings to regenerate.

Over time, this process causes a great deal of stress on the shrub species, which slowly began to disappear from the system. This will leave the banks exposed to erosion and bank slumping, as well as stimulate the invasion of non-native and upland species. This also causes the streams to hold water for shorter periods during the year, drying up many sections.

Community Pathway 2.1b:
The shift from PC 2.1 to PC 2.3 will occur during flood events. High volumes of water will rush through a stream system moving sediments and often uprooting vegetation. Once the waters have receded, they leave behind large, open areas of river-wash which is an exposed, mostly bare ground composed of sands, gravels, and cobbles.

State 4
Plant Community 2.2

Community 4.1
Plant Community 2.2

In the absence of the native willow and cottonwood seedlings, mules-fat (Baccharis salicifolia) will often colonize first and become the primary shrub species. It can often be associated with buckwheat (Eriogonum spp.), cudweed (Pseudognaphalium spp.), Lotus species and annual grasses (Bromus spp.) in the understory.

Community Pathway 2.2a:
The shift from PC 2.2 back to PC 2.1 occurs after an extended period of time without disturbance from grazing or floods. Since the removal of livestock and many large ungulates like deer and elk, some of these streams are showing signs of regeneration. The release from grazing pressure has given the cottonwood and willow species time to grow and reproduce from seed, bringing back some of the important bank-stabilizing elements lost from excessive utilization.

Community Pathway 2.2b:
The shift from PC 2.2 to PC 2.3 will occur during flood events. High volumes of water will rush through a stream system moving sediments and often uprooting vegetation. Once the waters have receded, they leave behind large, open areas of river-wash or exposed, mostly bare ground composed of sands, gravels, and cobbles.

State 5
State 3 - Plant Community 3.1

Community 5.1
State 3 - Plant Community 3.1

The lack of vegetation destabilizes the site and leads to a permanent state of non-native annual upland grasses. As the cottonwoods and willows disappear, so do their rooting systems that keep the water table high, offering water later into the growing season. Without these extensive roots, the water table begins to drop, leaving less water for new seedlings to regenerate. Over time, this process causes stress on the shrub species, which slowly began to disappear from the system. This will leave the banks exposed to erosion and bank slumping and also cause the streams to hold water for shorter periods during the year, drying up many sections of the streams.

Transition 3
Extensive restoration efforts can re-stabilize the site and move it back to the reference state by allowing the cottonwood and willow species time to grow and reproduce from seed, bringing back some of the important bank-stabilizing elements lost from excessive utilization.

Since much of the herbivores have been removed from the islands, many of the streams have shown signs of returning to Proper Functioning Condition (PFC), (Wagner et al 2004). Many of the streams showed signs of an upward trend rather quickly with willows (Salix spp.) and mules-fat (Baccharis salicifolia) beginning to establish, while some other streams have shown slower signs of recovery, gaining primarily herbaceous species with substantial rooting masses to assist in bank stabilization (Wagner et al 2004).