What is happening?
Over time, small shallow lakes such as the Lower Lakes can become shaded and overgrown. Dense shade prevents sun light reaching the subsurface zones suppressing water temperature, reducing overall productivity within the water feature. Submerged flora requires light in the upper photic zone of the lake in order for photosynthesis to occur and the ability of submerged macrophytes to persist while competing with other light demanding species.
The aesthetic value of urban lakes which are often visited by high numbers of people can also decline where dense vegetation obscures otherwise pleasant vistas. Lake edge woody vegetation typically comprises a mixture of low growing shrubs or small trees which are highly productive, including Willows (e.g. Salix cinerea oleifolia) species, Alder (Alnus glutinosa), Birch (Betula spp.) and other wetland species.
Typically such species regenerate within a short time after coppicing or cutting back. In cases where ponds or small lakes are neglected floating and bank side vegetation can quickly invade and engulf the whole aquatic system
1 . Further, residual leaf litter which is not decomposed by macro-invertebrates and microorganisms can form layers of silt on the bottom which may be problematic in such small shallow systems. However, intervention through strict but sympathetic management practices can maintain a healthy balance between the volume of vegetation in submerged and lake edge zones, light exposure and habitat available to fauna including macro-invertebrates, cover for breeding, roosting and nesting birds as well as mammals including bats. However, tree cover along lake edge provides benefit for a range of both aquatic and terrestrial fauna
2 . The leaf litter which is shed on the lake bottom provides foraging material for detritivores such as grazing and shredding macro-invertebrates. Leaf litter also affords substrate for frog spawn and/or potentially macroinvertebrates to deposit eggs and refugia for shelter the during winter months. Tree cover provides breeding sites, cover and foraging areas for a wide range of birds such as Water Rail, Moorhen, Mallard and terrestrial species. Bats utilise riparian trees for foraging with a particularly high abundance of winged invertebrates associated with waterbodies. Shade also suppresses algal growth by decreasing exposure to sun light, thus reducing water temperature. Therefore, management practices employed to thin out and control growth of woody trees will be sympathetic to birds, mammals and in-stream fauna which may utilise the Lower Lakes
3 . Coppicing, thinning and pruning back of trees will be strategically planned for a selection of overhanging trees, particularly fast growing Willow species and a dense overgrown area of Red-oisier Dogwood (Cornus sanguinea) further upstream. A number of trees on the islands and fringing the lake will be thinned to retain some cover for foraging and roosting birds and bats. Trees will either be coppiced or lightly thinned, no specimens will be completely removed. A number of fringe species which can invade from the lake edge such as Flag Iris (Iris pseudocaris) and Sweet-reed Grass (Glyceria maxima) may also be lightly removed in pockets but must not be completely removed to maintain habitat for breeding aquatic birds. A proportion coppiced wood will remain in-situ in the lake to provide micro-habitats for a range of fauna including Caddis larva and Beetle larvae while recently fallen decaying leaf litter will remain on the lake floor. To this end, work as detailed above will be completed shortly before the bird nesting season commences within a short time after coppicing or cutting back. In cases where ponds or small lakes are neglected floating and bank side vegetation can quickly invade and engulf the whole aquatic system
Why now?
In compliance with Section 40 of the Wildlife Act, removal works will take place before the commencement of bird & wild fowl nesting season.javascript:;
Extra Information
UCD-Environmental-Baseline-Review-2019-online.pdf (ucdestates.ie)
About Estate Services | The Natural Environment (ucdestates.ie)
Revised Acts (lawreform.ie)
About Estate Services | Sustainability (ucdestates.ie)
Area / Buildings:
Lower Lakes – Belfield Campus
Sources & Citations
1 Avon Wildlife Trust – Pond Management: http://www.avonwildlifetrust.org.uk/sites/default/files/wap15_pondmanagement.pdf
2 Freshwater Habitats Trust – Managing Trees around Ponds: https://freshwaterhabitats.org.uk/wpcontent/uploads/2015/10/Managing-Trees-around-ponds.pdf
3 Managing Plant Overgrowth within a Pond: http://www.pondexpert.co.uk/managing-plant-overgrowthwithin-your-pond.html
Naisc thagartha: Reference links:
https://freshwaterhabitats.org.uk/wp-content/uploads/2015/10/Managing-Trees-around-ponds.pdf
http://www.fingalbiodiversity.ie/resources/encouraging_garden_wildlife/Garden%20Ponds%20&%20Bogs.pdf
http://www.avonwildlifetrust.org.uk/sites/default/files/wap15_pondmanagement.pdf
https://www.hertfordshire.gov.uk/media-library/documents/environment-andplanning/cms/ponds-faqs.pdf
https://www.lifeinfreshwater.org.uk/web%20pages/ponds/Animal%20Communities.htm