Streams and rivers
Streams and rivers can provide significant wildlife value.
Where they can still behave naturally, they are important for many species including aquatic and marginal specialists like water vole and the banded demoiselle damselfly.
Water flowing in rivers and streams moves much faster than ditch water and creates the meanders we associate with healthy rivers and streams. The majority of streams and rivers found in arable landscapes are contained within flood banks. Man-made weirs, culverts and revetments along the course of a river can hinder wildlife, either by preventing access to the upper reaches of a river or by causing changes in the rivers morphology and rendering the habitat unsuitable. Added to this the changes in our landscape mean that there has been an increase in pollutants into our rivers and an increase in water taken from them.
Protecting streams and rivers plays a vital part in protecting the wildlife that depends on them. Reducing point-source pollution, run-off from fields and urban environments, and the removal of invasive non-native plants like Himalayan balsam can all play a vital part in protecting the wildlife value of our streams and rivers. Managing rivers and streams sympathetically can provide homes for a wide range of wildlife, and are vital feeding habitats for all UK species of bat. This is particularly true of the Daubenton's bat which specialises in feeding over water.
The main way to protect rivers and streams within an arable landscape is to maintain or improve water quality by preventing run-off reaching the water course. Managing the banks and bank tops sympathetically will also be of benefit.
Bankside vegetation should ideally have minimal intervention, particularly where sheer bank faces are present, or on sandy soils which are prone to erosion. If it is necessary to undertake mowing or cutting, try to restrict it to autumn or winter. Where possible try to alternate cuts along short sections to create a varied age structure of vegetation along the length of a ditch.
If there are trees along a river or stream which require work to maintain the health of the tree (e.g. pollarding), this should be done outside of the bird breeding season. Remember to check that there are no bats roosting in the tree. Retaining large trees, particularly on larger water courses, will be hugely beneficial for both birds and mammals like otters. Allowing small areas of scrub to develop along rivers frequented by kingfishers is highly beneficial, as they actively choose areas with overhanging scrub to site their nests.
Rivers and streams are rarely isolated features, so it is important to consider the surrounding features in management plans. Maintaining existing margins and/or extending buffer strips can help protect the watercourse from pollution from farm inputs and run–off, and also help to stabilise banks. Best practice suggests that a 6m buffer strip comprised of tussocky grasses and herbs will trap sufficient run off to prevent the majority of sediments reaching the water course, assuming a maximum gradient of 7o. Keeping a varied vegetation structure in the buffer strip greatly increases the value for resource protection and for wildlife. Tussocky grass provides year round habitat for invertebrates and small mammals.
Where rivers or streams are important for fish or shellfish, particularly salmon or white clawed crayfish, allowing dappled shade to develop along the river can help to prevent the water from getting too hot. Leaving some areas open and allowing marginal vegetation to develop is equally important, as this will provide habitat for invertebrates like demoiselles which require sunshine, flowing water and emergent vegetation to complete their lifecycle.
It is important to be aware of invasive species in watercourses, which left unchecked can choke out native vegetation and significantly reduce their wildlife value. For information on aquatic invasive plant species, such as Himalayan balsam, see links below.
Managing features in the main channel of rivers and streams is a complicated process, and, in most cases, requires consent. Where in-channel work is being discussed or undertaken it is essential to seek advice from the Environment Agency before beginning work and advisable to seek additional input from specialists.
Environment Agency website
See Wild Trout Trust for information on habitat management, including how to manage invasive plants.
Here are some useful case studies and articles about how farmers are putting Farm Wildlife into practice on their farms
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