At Sissinghurst we look after a variety of habitats that require careful management. It is important to get the level of management right; too little and the required effect will not take place, too much and delicate ecosystems could be damaged.
One such habitat that requires the right management is the lake area at Sissinghurst Castle. The lakes were created when they were dug out in the 16th Century and the clay was used to make bricks for the tower. Over the intervening years the lakes have filled with Rudd and extensive tree and vegetation growth have made for an excellent and differing variety of environments that are home to numerous animal and birdlife, invertebrates and amphibians. This all might look like a wonderful self-managing habitat but there could be nothing further from the truth.
We can control the amount of water that flows into the lakes by adjusting sluices but we have to take measures against the inflow of water borne weeds. We have all seen neglected ponds or other water bodies that can have a complete covering of algae. Whilst small patches can provide cover for fry of many aquatic species, a complete covering will absorb the oxygen in the water and, in the most serious of cases, can kill fish due to lack of oxygen.
Perhaps the simplest way of combating the spread of algae is by the use of barley straw. Tied up in large sausage like nets and staked into place at the inflow to the lakes, the straw will rot and as it does so will release chemicals that inhibit the growth of the algae. Any larger weed will need to be manually removed which is an arduous task so prevention is definitely better than cure!
Larger vegetation that cannot be controlled by barley straw but needs to be removed requires a more manual approach. Bulrushes are an attractive looking wetland plant but can spread rapidly if unchecked.
At Sissinghurst we have been clearing the rushes away to reinstate a view from our boardwalk across the lake. The view had been completely obscured by the bulrushes and they were starting to spread outwards. There was no clever technical solution other than to don waders and start pulling them out (fortunately easily done). The reeds are piled up to allow any aquatic wildlife to escape back into the water before being taken away. We will need to monitor this site and continue our removal programme as and when necessary.
Trees growing around a lake can give wonderful images of leaf dappled reflections and indeed the surrounds would look very bare without them. Willow, synonymous with lakes, can be a real problem though. Take a cutting from a willow, plant it in damp soil (even water) and there is a very good chance roots will develop and it will grow, such is the propensity for willow to root in damp conditions. And there lies one problem with lake management at Sissinghurst. We have extensive willow growth on the banks of our lakes and unchecked, will spread across the lake.
As the tree grows, its limbs spread and grow close to the water. Should the branch touch the water or become submerged then tiny fibrous roots will grow from the limb and take root in the lake bed. The new rooting will develop producing a sapling and the whole process starts again. By this method, over time, willow has the ability to “move” across a lake. Once again the only practical management is one of removal. By cutting the bank side willows and removing all branches from the water the spread of willow can be temporarily halted.
So, as you can see, the idyllic image of our lakes at Sissinghurst is one that requires careful management. It is an important feature of the property, not just for the abundant wildlife it sustains, but also to create a quite spot where one can sit down on a warm summer’s day, away from the hustle and bustle of the garden, and let time drift by.