Overview of Ice Plant Invasive
Ice plant invasive, also known as Carpobrotus edulis, is a succulent native to South Africa that was introduced as an ornamental plant and has become invasive. Ice plant invasive is a fast-growing plant that spreads quickly and crowds out native plants. Each ice plant invasive plant can produce over 500 fruits annually, with each fruit containing up to 400 seeds. Seeds can remain viable for up to 30 years, allowing populations to persist and continue spreading even after removal of adult plants. Ice plant invasive has spread to coastal dunes, cliffs, and scrublands, where it competes aggressively with native plants. More than 3 million acres of habitat have been invaded by ice plant invasive in California coastal areas.
Why is Ice Plant Invasive?
Ice plant invasive becomes invasive for several reasons:
Fast growth and spread: Ice plant invasive grows and spreads very quickly. Each plant can spread over 3-5 feet in the first year. In ideal conditions, ice plant invasive doubles its area every 6-18 months. The fast growth allows it to outcompete native plants by depriving them of light, space, water and nutrients.
Abundant reproduction: Ice plant invasive reproduces both vegetatively and through prolific seed production. Vegetative reproduction occurs rapidly as stems root at the nodes where they contact the soil, allowing a single plant to spread over a large area. Sexual reproduction results in over 500 seeds per plant each year. The tiny seeds are easily dispersed long distances by water, animals, vehicles, and human activities.
Long seed viability: Seeds of ice plant invasive can remain viable in the soil for up to 30 years. Even after removal of adult plants, the long-lived seed bank allows populations to persist and continue spreading.
Wide tolerance of environmental conditions: Ice plant invasive can tolerate a wide range of environmental conditions, including drought, salt spray, sand burial, and heat. This wide tolerance allows it to invade coastal dunes, scrublands, cliffs, disturbed areas, and wilderness.
Difficult to remove: Once established, ice plant invasive is difficult to remove due to its dense mats and deep root systems. Complete removal requires frequent monitoring and repeated removal of regrowth. Without follow-up treatments, ice plant invasive will quickly re-establish from any remaining roots, stems or the seed bank.
In summary, the rampant growth, abundant reproduction, long seed viability and wide environmental tolerance all contribute to the invasiveness of ice plant invasive. Controlling and managing this invasive species requires persistent and integrated management approaches to curb its spread effectively.
Impacts of Ice Plant Invasive on the Ecosystem
The spread of ice plant invasive has substantial negative impacts on the environment, wildlife and economy:
Displacement of native plants: Ice plant invasive forms dense mats that crowd out and displace native plants. In coastal California, ice plant invasive has replaced native vegetation on over 200,000 acres of habitat. The loss of native plants disrupts the local ecosystem, as native wildlife and insects rely on them for food, shelter, and habitat.
Alteration of soil properties: Ice plant invasive changes soil chemistry and composition where it invades. It increases soil acidity and decreases levels of nitrogen and organic matter. These changes can persist for long periods even after removal of ice plant invasive. The altered soil properties create unfavorable conditions for native plants to recover.
Increased fire risk: The dense mats and abundant dead plant material under ice plant invasive increases the risk of wildfires. The vegetation and oils of ice plant invasive are highly flammable, allowing fires to spread rapidly once ignited. Frequent wildfires further degrade habitat and prevent native plant regeneration.
Economic losses: Controlling the spread and managing ice plant invasive costs the California economy tens of millions of dollars each year. Voluntary programs and grants provide funding for control and restoration, while agencies and non-profits dedicate substantial resources to tackling this issue. However, limited funding and the vast scale of invasions mean that complete eradication is currently unrealistic.
Decreased biodiversity: The displacement of native plants and alteration of habitat by ice plant invasive threatens native wildlife, insects and other organisms. Over 40 species of native plants can be outcompeted by ice plant invasive, which provides little to no food or habitat value for native fauna. Reduced biodiversity can have ripple effects across the entire ecosystem.
In summary, ice plant invasive poses a severe threat to coastal Californian ecosystems, the economy and native biodiversity. Urgent action is needed to curb its spread and mitigate current damage in order to protect these natural resources for the future. An integrated management approach shows the most promise for sustainable control of this noxious weed.
Effective Methods to Control Ice Plant Invasive
Several methods can be used to control ice plant invasive efficiently:
Manual removal: Manual removal involves physically removing ice plant invasive plants by hand or using tools such as shovels, pruning shears and weed wrenches. This method is effective for small infestations but becomes impractical for large, established populations due to the dense growth and deep root systems. Manual removal requires frequent monitoring and retreatment to deplete the seed bank and control regrowth.
Prescribed burning: Prescribed burning uses fire in a controlled manner to remove aboveground vegetation. Due to the flammability of ice plant invasive, fire can kill mature plants and seedlings. However, burning may only provide temporary control as ice plant invasive can quickly regenerate from remaining roots or the seed bank. Multiple controlled burns are often needed, which can further degrade habitat quality. Strict regulations also limit the use of fire in populated areas.
Livestock grazing: Targeted grazing using livestock such as goats, sheep or cattle can suppress ice plant invasive by consuming stems and foliage. Repeated grazing treatments may be required to achieve long-term control. Grazing also helps break up dense mats, making subsequent control methods more effective. However, overgrazing must be prevented and livestock need to be restricted from grazing desirable native plants.
Chemical control: Selective herbicides, such as triclopyr and glyphosate, can be applied directly to ice plant invasive to kill plants and roots. Herbicide control needs to be combined with other methods like manual removal or retreatment of regrowth to achieve sustainable control. Extreme caution must be taken to avoid off-target damage to native plants and contamination of soil, water or habitat.
An integrated pest management (IPM) approach, using a combination of manual, biological and chemical control methods tailored to the site, shows the most promise for effective and sustainable control of ice plant invasive. No single method is sufficient, so employing multiple complementary strategies is crucial. Successful control also requires limiting disturbance to soil and native species as much as possible to aid the recovery of the native ecosystem.
Chemical Control of Ice Plant Invasive
Selective herbicides can be applied to control ice plant invasive when other methods are impractical or ineffective. The key points for effective and responsible herbicide use include:
Choose appropriate herbicides: Selective herbicides that target invasive plants while causing little damage to native species should be chosen. Triclopyr and glyphosate are commonly used to control ice plant invasive. These herbicides are most effective when applied from Spring through Fall, while plants are actively growing.
Proper application technique: Herbicides should be applied directly to the leaves of target plants using spray bottles or wipers to avoid off-target damage. Foliar application of herbicides allows them to be absorbed and translocated to the roots, providing more complete control than basal bark application alone.
Follow-up monitoring and retreatments: Herbicide application typically requires multiple treatments to control regrowth from roots and the seed bank. Retreatments should be conducted 6-12 months after the initial application. Long-term monitoring is also needed to identify any missed patches or new infestations.
Minimize environmental impact: Spillage, overspray and off-target damage must be avoided. Applicators should use anti-drift agents according to the product label, spray when winds are under 10 mph, and use shielded sprayers or wiper pads. Do not apply herbicides over water bodies or before rain. Always follow the usage guidelines on the product label regarding application rates, protective equipment, storage, and disposal.
Integrate with other control methods: For the best outcome, herbicides should be combined with manual control methods such as digging or pulling. This helps deplete the seed bank and limits regrowth, improving long term control. Selective grazing or prescribed burning can also supplement chemical control.
When applied properly and integrated with other management techniques, herbicides can provide an effective tool for controlling extensive infestations of ice plant invasive where other methods alone may not suffice. However, herbicide usage requires very careful monitoring to minimize risks to the environment, human health, and native ecosystems. IPM principles should always be followed for sustainable management of invasive species.
Preventing the Spread of Ice Plant Invasive
After controlling infestations, actions must be taken to prevent ice plant invasive from spreading again. Key steps for limiting spread include:
Monitor regrowth and retreat as needed: Following any control method, areas should be monitored regularly for regrowth from roots or seed bank. Manual removal, herbicide application or other methods should be repeated until no new growth is observed for at least a full year.
Limit soil disturbance: Disturbing the soil through tilling, grading or frequent mowing/fire promotes seed germination and vegetative reproduction of ice plant invasive. Remaining roots and propagules can produce new infestations from even small fragments. Non-essential soil disturbance in infested areas should be avoided.
Clean tools, vehicles and machinery: Seeds of invasive plants can be easily spread on tools, boots, clothing, vehicles or machinery. Anything used in infested areas should be thoroughly cleaned before leaving the site to prevent accidentally transporting seeds to uninvaded locations.
Prevent seed production and dispersal: Allowing plants to produce and disperse seeds will only worsen and spread the infestation, even after initial control efforts. Mature seed heads should be bagged and removed from the site before they release their seeds.
Educate others: Informing neighboring landowners, agencies and the public about invasive species spread prevention techniques is key. Educating others about how to identify ice plant invasive, the threats it poses, and how people can help curb spread through their own actions has been shown to aid management efforts. Coordinated community action and reporting can help detect new invasions early when they are most controllable.
Re-establish native vegetation: Encouraging the recovery of native plants is one of the most effective ways to prevent invasive species from re-establishing in an area. Selecting fast-growing native plants suited to the local habitat can help shade out and outcompete invasive regrowth while also restoring biodiversity. However, the seed bank of invasive species may still require management for some time.
Careful monitoring and follow-up treatments are critical after the initial removal of ice plant invasive plants. Preventing their spread through limiting disturbance, containing seeds, educating the public and re-establishing natives will help ensure hard-won gains made through control efforts are not lost by allowing this invasive succulent to return.
Native Flora Restoration after Ice Plant Invasive Removal
Restoring native vegetation is crucial after controlling ice plant invasive to prevent reinvasion and restore biodiversity. Key steps for successful restoration include:
Choose appropriate native plants: Select native plants that are adapted to the local climate, soil conditions, and natural habitat type. Coastal dune, scrub, and grassland plants should be used in areas previously invaded by ice plant invasive. A diversity of flowering plants, grasses, shrubs and trees helps establish a complex native ecosystem.
Propagate plants properly: Native plants can be established through direct seeding, live stakes, container plants, or transplants. The method chosen depends on the types of plants and site conditions. Proper propagation techniques help ensure high survival rates.
Prepare the site: The site must be made suitable for native plant establishment. This may require controlling any remaining ice plant invasive regrowth, tilling compacted soil, adjusting soil pH, or amending the soil with compost. However, excessive disturbance should still be avoided. Providing erosion control and irrigation also aids plant establishment.
Maintenance and monitoring: Follow-up maintenance such as hand-weeding, providing shelter, erosion control or supplemental water is often needed, especially in the first few years. Monitoring should be conducted to quickly identify and control any remaining or new invasive plants, and replace any failed native plants. Long term maintenance will be required as the seed bank of ice plant invasive may persist for many years.
Consider re-introducing wildlife: As the native habitat recovers, native wildlife species that were displaced by ice plant invasive can be re-introduced. This could include insects, birds, reptiles or small mammals that are natural parts of the coastal ecosystem. However, the restored native plant community must be well-established first to provide food sources and shelter. Re-introduction of wildlife must be done carefully through approved programs.
Restoring invaded areas after removing ice plant invasive requires patience and a long term commitment. Choosing suitable native plants, preparing the site properly, follow-up maintenance and monitoring are all needed to help the native ecosystem get re-established. Success also depends on controlling disturbance and any remaining invasive plants which can outcompete establishing natives. When done properly, native flora restoration helps return biodiversity and ecological function to areas degraded by invasive species.
