Invasive Phragmites in Canadian Ecosystem

Invasive Phragmites in Canadian Ecosystem

Introduction

Invasive species refer to the species that have, especially through the assistance of human being, become established in new ecosystems. Even though it is not possible to establish exactly the number of invasive species residing in Canada, it estimated that more than 1,400 invasive species including insects, fish, plants and invertebrates stay in the country’s waterways and forests. Non-native species are dreaded for their capability to reproduce at a faster rate as compared to native species. In addition, they are none to offer stiff competition for habitat and food.

One of the major invasive species on land plants in Canada is the Common reed, commonly referred to as Phragmites. Common reed is an invasive species that originated from Eurasia. The species is causing significant damage to the coastal wetlands within North America. The species is also known to create dense stands that are able to displace other plant species in wetlands. Common reed is a tall species, warm-season and sod-forming grass. It has herbaceous grass that is able to grow up to 20 feet, and its stems and tan or grey seeds make it be easily identified. The plant has cane-like stems, and they are hollow, adaptations that make it survive in wetlands. The plant was native to Africa and Eurasia, but it has spread globally especially in Mexico, the US, Argentina, West Indies and Australia.

The major ecosystems where the common reed is found are Oak-hickory, Ponderosa pine, Oak-gum, Elm-ash-cottonwood, Plains grasslands, Wet grasslands and Sagebrush. The adaptation of Phragmites is significantly impacted by its methods of reproduction. The plant reproduces through stolon fragments, roots via rhizomes or by dispersing seeds. Studies by Quirion et al. (2018) noted that the dispersal of seeds could occur through air, water, human actions, movements of animals, and through equipment for example boats, ATVs, trailers and horticultural trade. One of the main methods of reproduction adopted by Phragmites is the growth of their rhizomes horizontally for a number of metres per year. Likewise, vertically, the plant can grow for 4 cm each day, and it produces thousands of seeds yearly.

In its native ecosystem, Phragmites faces off its preys and other species by out-competing them for nutrients and water. In addition, the plant releases toxic chemicals from its roots that make the neighbouring species depending on the surrounding soil to die. Phragmites has the ability to survive in disturbed waters, and it is known as one of the plants that are first to colonize a new ecosystem (Cvetkovic, Wei and Chow-Fraser, 2010). In addition, it is sensitive to increased levels of salinity, drought and low conditions of oxygen.

The status of the common creed in the ecosystem is that it is a healthy population that can destroy habitat and reduce biodiversity for other species. The lifecycle of Phragmites follows five timelines that make it to effectively adapt to its new ecosystem. The first timeline is dormant, that occurs between November and March. The second timeline is germination, and it takes place between April and May. The primary vegetative growth, which is the third timeline occurs between June and July. The fourth timeline is flowering, and it takes place between August and September. The last timeline that occurs between September and October is the translocation of nutrients (Rhemtulla et al., 2002).

Invasiveness

According to the Ontario Ministry of Natural Resources (2011), Phragmites is a kind of grass that is native to Eurasia and has spread widely across Ontario. The various pathways have made the species to penetrate in Canada. The most important vector that is used to spread Phragmites is heavy equipment, for instance, during road construction. Roads have in various regions have enhanced the degree of landscape connectivity, leading to increased transport of plant fragments and seeds. Even though how the Phragmites were established in Canada is not clearly known, researches suspect it was entered the country through ballast waters in the 1700s and 1800s (Ontario Ministry of Natural Resources, 2011). The horticultural trade was also a possible way through which it was established, and despite its invasive features, it is still being practised at garden centres.  

Phragmites was first noticed in 1910 at Southwestern parts of Nova Scotia and later spread through St. Lawrence River to Quebec. Through the application of genetic markers, recent research has indicated three major lineages that led to the introduction of the glass in North America. One of the lineages was the endemic and native widespread. The second lineage whose nativity is not well-known occurred across the Southern region of the US, FROM California and finally to Central America. The third lineage in the introduction of invasive species from Europe.  One of the major reasons as to why Phragmites were successful in spreading and establishing in Canadian habitat was their ability to reproduce in disturbed areas. For example, the species can take over a region where there is a degradation of environmental stress. This is because other naïve species that may be common in a certain niche are not able to adapt to the changes in the environment and harsh weather conditions.

Impact of Invasion on Canadian Ecosystem

Loss of species richness and biodiversity

Through the creation of monoculture stands, invasive Phragmites leads to a reduction of biodiversity. For example, the species are able to crowd out natural vegetation and prevent native wildlife from utilizing the region for nutrients and water, leading to a decrease of animal and plants biodiversity. In addition, the toxins that are produced by its roots impede the growth of other species, and they kill other plants neighbouring it. The high biomass of Phragmites blocks the light to other plant species apart from occupying growing space of plant communities that have low growth. The rigid and tough stalks of Phragmites also decreases habitat besides impacting on the food supplies for other wildlife, thus exposing other species to the risk of becoming extinct.

Loss of local habitat

The monoculture stands established by Phragmites also have adverse effects on the availability of natural habitat. As the natural wildlife navigates through the habitat, they are restricted by the tough and rigid stalks of Phragmites. According to the study done by noticeable reductions of habitats were seen in meadow and savanna habitats. Approximately part of the meadow habitat was lost between 1931 and 2015 due to invasion of Phragmites.

Changes in Hydrology

The excessive-high metabolic rates depicted by the invasive Phragmites can have adverse impacts on the water cycles of the ecosystem in Canada. For example, their monoculture stands are able to reduce the levels of water, since water is transpired faster as compared to how it would in a region covered with the native vegetation (Chantel, Gillian and Patricia, 2018). The engineer concepts of the ecosystem are also affected since new strategies need to be adopted to maintain the level of water at optimal levels. According to Mary and David (2012), the monoculture stands can reduce water levels within the isolated and ephemeral wetlands that act as the habitats of most amphibians (Hecnar and Hecnar, 2004). The features of rapid growth, as well as the slow rate of decomposition, causes a huge volume of ground biomass. Vegh (2016) argues that this results in a sediments depositions that affect the drainage of the ecosystems.  The release of nutrients is also affected by the carbon that is released by dead stalks of the Phragmites.

Increased cases of fire hazards

As a result of dead stalks accumulating in the ecosystem, the possibility of fire is high. This is because the dead stalks are dry as well as combustible. Individuals and organizations are faced with the challenge of managing dead stalks, implying that the ecosystem may experience more problems of fire in future.

Social and Economic implications

As one of the examples of invasive species, Phragmites can have negative implications on the social and economic development of the region. For example, due to their ability to colonise roadsides and ditches, Phragmites can impact the drainage systems and affect the crop yields (Harvey and Weatherhead, 2006). The economic effects include the high costs incurred by Ontario to control the species. In addition, the monoculture stands affect the values of the properties in the neighbouring areas, thus causing aesthetic concerns.

The Negative and Positive Impacts of the Invasive Phragmites

Coastal marshes have known to cause various risks that lead to a rise in sea levels and natural disasters (Seth et al., 2017). In addition, human activities have been the main cause of disasters like Hurricane Katrina. Studies have indicated that based on its high productivity, slow rate of decay and limited capability to export litter, Phragmites might counter the challenges that rise of sea level may cause. This is one of the main positive impacts of these species on humans. Nonetheless, Phragmites has more negative effects that outdo its benefits. For example, as noted earlier, the monoculture stands impacts of properties, thus lowering the values of nearby property. This makes landowners incur losses when they are selling their properties. Besides the above mentioned negative effects on the ecosystem, which further affects the food production for human in Canada and neighbouring regions, Phragmites also affects the recreation sector.  The height and dense of the plant makes it difficult to walk within the areas inhabited by the plant. As a result of reduction of natural wildlife population, Phragmites limit the recreational values for hunters, birdwatchers and hikers (Ontario Federation of Anglers and Hunters, 2015).

Strategies for Controlling and Eradication of Phragmites

As a result of the extensive rhizome system of the invasive Phragmites that is found underground, the application of a single method of controlling the plant is not adequate. Actually, any single disturbance of a region can trigger the spread and density of Phragmites. As a result, the Ontario Ministry of Natural Resources advocates for the adoption of an Integrated Pest Management (IPM) plan. This plan integrates two or more approaches that are followed up by monitoring, reassessment and treatment if it is deemed necessary. The management control techniques are flooding, application of herbicides, mechanical excavation and prescribed burning. The section below discusses the major strategies of controlling and eradicating Phragmites.

Application of Herbicides

Even though the use of herbicides is not treated as the ideal solution, the impacts of allowing the Phragmites to expand can offset the detrimental impacts of using pesticides. When applying herbicides, it is vital to obtain permits and regulations, as stipulated by the Pesticides Regulations 63/09. Under Section 33 of this Act, Class 9 pesticides are exempted for managing natural resources (Ontario Invasive Plant Council, 2015). When selecting the best herbicides to use while managing Phragmites, it is recommendable to choose those which are specifically made for grass species. For example, herbicides with high LD50 values have a low level of toxicity for wildlife. Herbicides that are used to control Phragmites should have the ability to translocate from the sites they are applied that is stems and leaves down to the roots in order to effectively kill the whole plant.

In North America, the two types of herbicides that are proved to be effective in controlling Phragmites are imazapyr and glyphosate. Even though the two chemicals are formulated using various common brand names, the former is more effective than the latter, but it is expensive. A management plan that integrates the two chemicals can lower the costs of controlling the species while a high level of efficacy is achieved. One of the advantages of using a different active ingredient is that it reduces the possibility of Phragmites becoming resistance to other herbicides.

The stands of invasive Phragmites can be controlled with herbicides using various methods that include wicking and spraying. The appropriate technique depends on the features of the site, logistics and the entire management plan adopted in the region. Based on the fact that herbicides have a broad spectrum, it is essential to focus at stands and monocultures that are made up of huge fraction of Phragmites besides limiting the application on the upper canopy to avoid affecting the vegetation found on the upper canopy.

The usage of herbicides on the stands with lower density is also effective since less of it is used to regulate the strands, and native species can respond effectively when the invasive species are eliminated. For smaller stands, wicking is more effective since it allows herbicides to be applied on specific plants and negative effects on native vegetation are avoided. Hand-wicking entails making direct contact with individual stalks using absorbent gloves that are soaked in herbicides. Even though hand-wicking requires more labour, it can be effective when weather and wind conditions do not support the spraying technique.

Prescribed Burning

This technique entails deliberate and planned use of fire by authority, and it can be integrated into the management plan after the application of herbicides. This method also requires the controlling personnel to obtain and follow the permits and regulations. Due to the extreme dangers of using fire to control Phragmites, it should only be performed by authorized and trained personnel. The main duty of fire is removing biomass that inhibits the expansion of native vegetation apart from providing sources of materials for their reproduction. This method is effective since it is able to eliminate the biomass that has become a major challenge caused by Phragmites within the Canada ecosystem. Optimal benefits of using fire to control Phragmites are attained when the practice is done after at least two weeks after treatment using herbicides and after rolling of the stalks that are dead.

It is worth to note that the use prescribed burning before herbicides are applied is not an effective technique, and may result in expansive growth of rhizomes leading to higher growth of the stands. While using this method, it is recommended that fire is not set on dead strands since it may be difficult to contain the fire resulting is personal safety hazards.

Flooding

Flooding stands is a challenging method and has diversified outcomes. For the flooding to be effective, the stand should be in regions where levels of water are easily controlled, and the cutting should be done at the lowest height. In addition, flooding should be performed during late summer with an objective of maintaining and promoting native vegetation while at the same time preventing the reoccurring of invasive Phragmites. Ontario Ministry of Natural Resources. (2011) stipulates that for this method to be effective, the levels of water should be 1.5 metres higher than the stand. In cases of wet sites where such height is not feasible, it is recommended that the newly emerging species be drowned using shallower levels of water. For the drowning process to be fruitful, the standing dead biomass should be removed by rolling, burning or cutting. The major advantage of removing dead stalks that extends beyond water service is that it reduces the diffusion of oxygen to the root systems.

Conclusion

In the management of Phragmites, most of the data is focused on the wat land managers can promote early detection and make a rapid response to small populations.  Such responses and control are not feasible in regions where invasive Phragmites are rapidly expanding or growing. In the areas where the species are expanding, containment and suppression strategies can be warranted. However, the potential benefits of the projects adopted by the management plans are required to be evaluated against the possible drawbacks. This implies that there is a need to have adequate data regarding the managing of large invasive Phragmites since the diversion of resources from other government projects may have questionable efficacy besides taxing people beyond what they can be committed to in a long-term.

The likelihood of future spread and negative effects of Phragmites is high. This is because they are able to expansively spread in a disturbed environment like drainage ditches and roadsides. In addition, the complexity of managing invasive Phragmites will make it spread widely. This is based on the fact that the managers will be required to create control mechanisms that will effectively eliminate the invasive Phragmites population while at the same time not impacting on the native vegetation, a process that can be difficult (Row, Blouin-Demers and Lougheed, 2012). Another reason for the future spread of these plants and have negative impacts on the world ecosystem is their ability to produce huge quantities of seed and hastily colonize new habitats. In addition, Phragmites can withstand unfavourable environmental conditions, for example, salinity, various types of soil and pH (Hecnar, 2004).

One of the major next steps of managing invasive Phragmites is not to purposely plant it.  Currently, the plant has become a challenge on the Canadian ecosystem. While the government continues with its management plans to control the spread of invasive Phragmites, it should also ban the planting of the species by gardeners to mitigate its spread. As noted earlier, invasive Phragmites are transported through construction equipment (Anderson, Hayley and Tassie, 2013). Even though the Canadian Government should not ban the importation of building raw materials and equipment, the constructors should be encouraged to brush off their clothes and make sufficient cleaning of all equipment on the customers’ sites to ensure the seeds are transferred to Canada-based sites.

References

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