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Himalayan Balsam – A Roman River Success Story

Himalayan Balsam is now a common sight along many river banks in the UK. It is non-native and was imported as an ornamental plant to be used in people’s gardens. Unfortunately it did not stay within these gardens for long as it produces seed pods in late summer that can shoot its seeds great distances allowing it to disperse far and wide especially it the seeds can enter a water course.

This plant especially likes shaded moist areas so many river banks are prime spots for them and the running water allows their seeds to be deposited further downstream. This plant also seems to out compete other plants and dominate in the areas it is found, which is not only a problem in terms of reducing plant diversity but this plant completely dies back to nothing after the first frost leaving the banks bare and this increases the amount of sediment that is washed into the channel during heavy rainfall.

Another problem with this plant is that pollinating insects can’t get enough of it, so I guess you are thinking surely that’s a good thing when pollinating insects, especially as some species of bee are on the declining. Yes it is good news for the individual insects but bad news for other native plants that rely on these insects for pollination as the bees will select Himalayan Balsam over other native plants which increases the problem of this plant dominating an area.

We are hopeful that the sight of Himalayan Balsam dominating the banks of the Roman River is a thing of the past after a successful project to eradicate this plant is showing positive signs. This project began in autumn 2011 when the Roman River was surveyed to pinpoint and record the location of this plant along the whole stretch. This was achieved by a surveyor walking the whole river and using a GPS unit to record the grid references of not only stands of plants but also individual plants.

Once the data was collected the locations were mapped so the full extent of the problem could be seen and decisions could be made on how to tackle it. The next step had to wait until the plant had regrown and were visible once more but we had to make sure we tackled them before they were ready to seed as we wanted to remove them before we ran the risk of releasing the seed and allowing the plant to return the following year. Once found they are easy to remove as they have very shallow roots and can be easily pulled roots and all. We attempted to remove every single plant including tiny little seedlings that were scattered everywhere. Although the plants were easy to pull it was hard work as the weather was extremely humid but we had to work in long trousers and long sleeved tops as we were working amongst sting nettles in most instances. Once removed we left the plants in-situ, once again to avoid spreading the problem as removing them from site could have spreading this plant to other areas. The removed plants were checking a few days later to ensure they were dying off and not re-growing. This was done for every plant and stand of plants identified during the surveys in the previous autumn and was achieved with help of Essex Wildlife Trust staff, volunteers and school groups who came along to help us out. We ended the summer of 2012 optimist that our efforts had been worthwhile, and then in the summer of 2013 we ventured out again to see what we would find and were delighted to discover that almost no plants Himalayan Balsam were found. In places where the area was dominated by Himalayan Balsam we had to search very hard to find any and in some areas this plant was complete absent. We are now hopeful that with a bit more work next year we may be able to completely eliminate this plant from this river and it also gives us hope that we can achieve similar results along other rivers too.

If you have Himalayan Balsam in your garden then please consider removing it. We know it is a very pretty plant and that it is great for bees but once it gets out into the wider environment then it can cause major problems and it is very difficult and expensive to control!

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The topics below represent the pressures that many waterbodies in the Combined Essex catchment face. They have been divided into six main categories, but it is quite often that these categories can overlap as pressures relate to each other.

Diffuse pollution occurs as water moves across the land or through the ground and picks pollutants. These pollutants can come from a variety of places, including urban and field run off. The pollutants that enter the river can range from sediment to toxins to excess nutrients, meaning that diffuse pollution can cause a whole range of different issues. The variety in these pressure groups means that it is something that can be quite difficult to tackle. It requires groups of people, business and stakeholders to work together in order to solve this problem.

Fish should be able to travel up and down a river freely, allowing them to move and breed in the most suitable habitats for them. It is important that fish populations do not become isolated, as this makes them more susceptible to disease and puts pressure on their survival. Unfortunately, there are often many barriers along rivers that prevent fish from being able to migrate up and down stream. Where barriers have been identified, they will be seen as a ‘pressure’ on a waterbody. Thankfully, there are many solutions now that can be put in place to aid fish passage, even over large barriers.

The flow in a river can vary greatly throughout the year as rainfall and run off can have an effect. This is a natural process. It is when flow is impacted by non-natural processes that it can cause problems. Sometimes, water can be intercepted or removed from a system; this will reduce the flow, therefore changing the habitat conditions. Some species are happy in high energy rivers. This means that when flow is reduced, these species will no longer survive. The opposite of this can occur when excess water is entering a river, for example through increased runoff. Low energy systems then become high energy and displace the species that live there.

A species that is not meant to be found in a particular area is known as an invasive species. Invasive species can be from a different habitat or a different country altogether. Most of the invasive species that we find on our rivers have come from other countries – plants that people have imported for their gardens or animals that have been released for food or by animal rights activists. Control of invasive species requires a lot of time and effort. We are fortunate that we do have a range of methods to manage most of the invasive species that cause havoc on our rivers, but there are still some which we are still struggling to control.

Many of our rivers have been heavily modified over the years as rivers have been used for a wide range of purposes. Physical modification is one of the biggest factors that causes our rivers to be unhealthy. The issues that it can cause range from reducing habitat, preventing migration of mobile species, and even have an effect on the water quality. Where structures and modifications are no longer in use or necessary, they should be removed to allow the river to regain its natural state. Unfortunately, this action is not always taken which means that many of our rivers are over straightened and contain redundant structures. It is possible to return a lot of our rivers to their natural state, through one off projects, but in other cases it is not possible as the river has been changed to protect assets or manage flooding. It is recognised that some modifications cannot be removed without having severe negative impacts both socially and economically.

This is pollution that comes from a single identifiable source. The pollution entering the river could include a whole range of pollutants. Some point source pollution is known about and licences, for example sewage treatment works. Other sources are not licensed, and therefore work needs to be done with landowners to fix the problems that are allowing the pollution to enter the river. Point source pollution is more easily controlled than diffuse pollution as it often only takes one management approach to solve the issue.