Introduction
When I think of reedbeds, my mind conjures wonderful pictures of calm slow-flowing waters. Gently swaying reed, changing colours from golden yellows, purples and green with differing time, light and season. The noises made by their often-secretive inhabitants – the “plop” of a Water Vole entering the ditch, the pinging of Bearded Tits or the rustling of reed as a Bittern stalks its prey on the edges of a pool. This peaceful impression often hides both the variability of the habitat (a good reedbed is a mosaic of many ages, structures, depths and species) and the amount of hard graft it takes to make a reedbed as ideal as possible for its wide variety of inhabitants – who often have very different likes and dislikes when it comes to their habitat.
Photo: Ryan Doggart
Here at Titchwell Marsh, our reedbed has been an important part of the reserve for decades and is home to several key species including breeding Bittern, Marsh Harrier and Bearded Tit. To keep the habitats just right for these species, the reedbed has been managed in a pretty traditional manner involving drying out sections of the reedbed every winter and cutting them (usually with brushcutters) on a rotation every couple of years. Alongside this, we get the amazing amphibious reed-cutting machine called a Truxor to come in and open up some of the ditches, removing any encroaching reed from the banks. Both of these types of management help to keep pools and wet edges open for Bitterns to feed in while also preventing too much reed litter from building up and the reedbed from drying out. On the flip side, both Marsh Harriers and Bearded Tits rely on these drier, older areas, so when managing a reedbed a mix of ages of reed is key - variety really is the spice of life!
These methods do have their limitations, however. Reed is incredibly fast growing and come the end of summer, the areas that the reserve team worked hard cutting in the winter have grown back to their original height. While the reed is growing, it provides a very different habitat to a fully grown stand, often much more open and sparsely vegetated, potentially attracting different wildlife to use it. But – blink and you’ll miss it! To have these in-between habitats for long enough for birds and other wildlife to use them regularly, the vigour and growing speed of the reed has to be reduced. This is the main principle of a new form of much larger-scale reedbed management known as “rejuvenation”, that has been used over the last couple of years to great effect on other RSPB reserves such as Ham Wall in Somerset. This approach is applied to a whole compartment, so a significantly bigger undertaking but it also brings potentially big benefits. So, how does this all work? Well, in simple terms, over several years we do everything that the reed does not like (cutting, flooding hard in the winter and drying to out in summer) with the aim of almost killing the reed. Meaning when we do let it grow again, the plants do not have the energy to grow and spread quickly, resulting in a much longer time before regrowing into a full stand again. This also has the benefit of completely resetting the area, giving lots of wet areas for Bitterns to feed in. It’s not just the end result that will deliver for wildlife, as every stage of the process provides some interesting habitats and opportunities. With all of these benefits in mind, we have decided to try out this approach in one of the reedbed compartments at Titchwell.
So, what will this look like on the ground?
First things first, we have chosen Reedbed Pool (also called Compartment 12, see on the map below, in the north-west corner of the reedbed next to the West Bank Path) to try out this new method. As although it is a great spot to see ducks in the winter, it is relatively lightly used and has the potential to be much more interesting.
Reedbed compartments
We are starting this work this coming winter, which will begin with gradually lowering the water levels in late autumn. The aim here is not to completely dry out the compartment, just lowering them enough to allow the next step – cutting. The plan is to completely clear the whole compartment of reed – I appreciate this is going to be a big change but bear with us! Due to the sheer scale of cutting needed, the cutting will be done by the Truxor, with the aim to cut as close to ground level as possible. The reed will then be stacked or burned where appropriate. Once the cutting is done, the whole compartment will be flooded with as much water as we can possibly fit on there for the rest of the winter. Deeply flooding the freshly cut reed should deprive the reed the air it needs to grow and repair itself – the first step in reducing its vigour. At this stage, reedbed pool will be a large area of open, fairly deep water, so should be inviting for a range of winter wildfowl.
At the end of winter/early spring we will begin to draw the water levels down, aiming for a depth of around 20-30cm (the ditches and pools will be deeper), to provide perfect feeding grounds for heron species. At Ham Wall, they found providing these great feeding opportunities early season were key in getting Great White Egrets to breed there – and with two breeding-plumaged birds present in the reedbed at Titchwell for the last couple of years (with no breeding attempts seen), this could make all the difference. After holding these levels for most of the spring, the water levels will then be dropped further from late May exposing mud and reed stubble – which should provide great habitat for passage waders such as Wood Sandpiper, before being allowed to dry out as much as possible throughout mid-summer – again to stress the reed. At this stage the compartment will mostly be exposed mud, stubble and low vegetation, with some water in the deepest pools and ditches. The water levels will then be allowed to slowly increase into September, again providing great feeding habitat for passage waders in early autumn. Then continuing to build into those “splashy” conditions for herons to feed in.
The whole process will then be repeated for several years until the process has had the desired effects on reducing reed vigour. The spring/summer seasons will provide us with habitats that we do not currently have on the reserve during the management, with almost fen-like areas possible (dare we dream of breeding Black-winged Stilts or Black-necked Grebe?!).
Striking a balance
While this exciting stuff is happening in Reedbed Pool, we will continue to manage the rest of the reedbed as we have been – with particular focus on providing dry/older areas perfect for Bearded Tits and Marsh Harrier.
Exciting times ahead!
Ryan
Titchwell Warden