Management Objectives for a Semi-natural Woodland

Management Objectives for a Semi-natural Woodland Niamh Fitzpatrick An effective and long term successful management plan of Derrybeg woodland is critical to conserve and protect the biodiversity of the site. To do this, the first and most important step is the implementation of a bassline study. This bassline study will provide information on the flora and fauna that is present on the site, allowing you to devise an appropriate management plan. The first management objective of Derrybeg Wood is to manage the mixed broadleaf woodlands which includes, oak-ash-hazel and wet willow-alder-ash. The management of these woodlands is imperative as they are natural or semi natural woodlands of high ecological importance. Throughout the management its vital that one firstly maintains and if possible restores the woodlands natural ecological diversity. The main technique for the management of these woodlands is coppicing. However, as Derrybeg Wood has not been actively managed for several decades, firstly it would be necessary for the standards to be thinned out. This will allow more light for the understory. By thinning the broadleaf species, it removes the less desirable or trees that are not as healthy as well as giving the remaining trees more space to develop (Betts Ellis, 2009). Thinning allows light onto the woodland floor, thus encouraging an understorey of small plants, shrubs and trees to grow. This generally occurs naturally in many woodlands i.e. as weaker trees die, thus this step is not causing any negative impacts on the surrounding flora and fauna and is simply working with nature (Betts Ellis, 2009). In terms of coppicing these broadleaved woodlands, all the multi-stemmed broadleaved trees and shrubs that occur together will be cut down to ground level. The size of the coppice coupes will need to be proportional to the woodland area (Betts Ellis, 2009). For this woodland, coupes of 1-2 ha would be suitable. For optimum coppice growth to be achieved, their density will be kept between 30% and 50% of the canopy. It is preferable to maintain coupes that are irregular and elongated in shape compared to those that are square or regular in shape because they create richer edge habitats (Betts Ellis, 2009). Coppicing works extremely well for the woodland on a whole. It creates ideal conditions for many different species. The influx of light is optimal for some wild flowers in the first few years after cutting. Also as the coppice grows and becomes denser, excellent conditions are created for nesting birds which are present on site (Betts Ellis, 2009) This is a long-term management objective that needs to be monitored and carried out over several years. According to a study by (Betts Ellis, 2009) the stools are expected shoot and in 5 to 20 years they will produce a crop of poles that will need to be cut again. As Red Deer are present in this woodland the advantage of the richer edge habitats may be lost unless they are kept out for the saplings to be able to regenerate. Deer can cause major problems as they are tall and the coppice takes a lot longer to grow beyond the reach of the Red Deers mouth (Betts Ellis, 2009). In order to prevent the deer from entering this site, a deer fence is the most effective form of protection. In terms of natural barriers, brash is an excellent and effective alternative. Objective two: The second objective is to remove the rhododendron that is present in approximately half of the woodland. From the bassline study, we found that the level of infestation varies throughout this woodland i.e. near the pools in the centre of the woodland and under the birch and oak, there is heavy infestation as well as near the eastern half of the woodland, within the conifer stands. These heavily infested areas are priority and will be cleared first. The bushes that are largest and most mature need to be removed first, therefore removal will begin in the middle and work outwards rather than starting on the edges with the youngest bushes. Its important to remove these bushes first because they have the highest yield of seeds, thus causing the biggest threat to the eradication of this area. Once these major seed sources have been tackled, the minor seed sources will become a priority. (Edwards, 2006) The technique chosen to remove the invasive will depend on many factors such as; the height in which its growing, the level of invasion and the accessibility to the area. for this site the removal of the invasive will be broken up into three different steps; The initial removal of the invasive the stumps will be cut therefore leaving no live shoots or branches. This will occur from September to March and the cut material will be removed to a suitable area to be burned. Only a small number of burning sites will occur as it creates more areas of bare ground, thus providing more areas for the seeds to thrive. (Kent Wildlife Trust, 2017) Controlling the stems and roots young bushes, residual seedlings and any regrowth will be treated using a foliar spray that contains an adjuvant to enhance the performance of the herbicide. This is necessary to remove the waxy layer that is present on the surface of the leaf (Kent Wildlife Trust, 2017). This will occur from May to October, preferably when the weather is dry. Mature bushes will then be treated using a stem injection treatment, i.e. cutting the main stem to allow a hole to be drilled enabling the use of the herbicide. (Edwards, 2006) Follow up treatments Its critical that these treatments are carried out thoroughly ensuring all ground is covered before moving on to a new site. If not, the invasive will re-establish. The rhododendron must be monitored and re surveyed at the end of every growing season to identify if there is any re-growth (Edwards, 2006). From this any follow up treatments can be established. Herbicides dont transport within the phloem of the plant, thus its necessary to repeat this process to ensure that the invasive is dead and cannot re-grow. (Betts Ellis, 2009) Its extremely difficult to achieve the complete elimination of rhododendron and it is a very time consuming process, however if its controlled until the surrounding trees close canopy then shading will halt its development (Betts Ellis, 2009). Additionally, as much of the rhododendron invasion occurs within the conifer stands, the dense evergreen crowns of these conifer species have a heavy shade, thus preventing the Rhododendron regenerating within the stand (Betts Ellis, 2009). In a report from the forestry commission (Edwards, 2006), it was recommended that the management plan should occur over a seven-year period, therefore these steps including the follow up treatments will take place over seven years to ensure the complete eradication of the invasion of rhododendron in this woodland. (Edwards, 2006) Objective three: The third objective for Derrybeg wood is the development of rides or glades. A ride is a linear open space within a wood that is formed for the need of access (Stephens, 2005). Rides generally have a hard-surfaced track which make up some of the width and they are usually made up of several zones. A path or track becomes a ride when it is wide enough for there to be an opening in the canopy, allowing sunlight to reach the ground (Stephens, 2005). The first step in this objective is to survey all potential rides to establish which rides to open or create. This step is critical to choose the ones with greatest potential. All archeological features i.e. wood banks will be carefully considered to prevent damage in the process of creating or widening a ride (Stephens, 2005). The depth of the ride will be equal to or greater than the height of the adjacent canopy. Rides that are less than this width quickly lose any benefit gained in the early years (Stephens, 2005). The rides will have a wavy edge as this has a greater wildlife benefit. The wavy edge maximises the woodland edge, thus increasing the habitat diversity. In areas where wood mice and red squirrel are present pinch points will need to be included at no more than 100-metre intervals (Stephens, 2005). This is important as they are arboreal mammals which generally dont like to travel along the ground. Thus, they require aerial runways to cross open spaces. Rides that are w ider can also cause disturbances to the population and subsequent decline if links across them are not provided. The rides will be opened out to ensure maximum sunlight. It will run on the east-west line rather than the north-south line because east-west lines are in the sunlight for longer (Stephens, 2005). They warm up earlier in the year and cool down later and warmth combined with sunlight will promote the greatest wildlife benefit. The sunny ride edges will rapidly develop grasses and several plants that may be scarce or not found elsewhere in the wood e.g. violets (Stephens, 2005). Shrubs may grow on ride edges and this is a great food source for many butterflies and other insects which are present in the wood. Many flowers and butterflies present favour open-space environments at the woodland edge and therefore should thrive from this being extended (Betts Ellis, 2009). The careful management of open habitats is significant as it introduces greater habitat diversity. It enco urages a larger range of species as many prefer the edge of habitats for feeding due to the higher level of herbs and the larger invertebrate population (Betts Ellis, 2009). Once the rides have been identified and created, its important that they are maintained and managed appropriately for the following 20 years by doing the following; Mowing the area where the greatest amount of sunlight occurs every year. Cutting a herb or shrub zone once every three to five years. Cutting a transition zone between the herb / shrub zone to the high forest on an eight to twenty-year coppice rotation. Controlling the presence of deer, as this is required over an extensive area, culling is the most practical method as opposed to fencing. (Stephens, 2005) Objective Four: The management of the wildlife present in Derrybeg Wood is another significant objective. Many species present in the wood are protected or threatened per the IUCN red lists for example the red squirrel and the lesser horseshoe bat. These species are protected under the Wildlife (Amendment) Act 2000. In addition, the lesser horseshoe bat is also protected under the EU Habitats Directive. Given the conservation importance of these species its important to follow guidelines in relation to their management and the overall management of the wood. The red squirrel Sciurus vulgaris, is a significant species present in this woodland, and it is critical that they are managed effectively to prevent their decline. As grey squirrels are not present in this woodland, food supply is one of the most important factors affecting the red squirrels population density. The management of the conifer species is important to provide a continuous food supply for the red squirrel. Generally, conifer species are of variable quality in terms of being a food source (Red Squirrels Northern England, 2017). The amount of seed produced depends on factors such as the age of the trees, thus conifers should be managed depending on the state of the woodland (Red Squirrels Northern England, 2017). The management of the conifer species in this wood will include; Sustaining a permanent proportion of the forest that is made up of stands of seed bearing age. This is important because conifer species dont generally produce cones every year. Many species can take up to seven years between cycles and some species dont start to cone until they are 15-20 years old. (Red Squirrels Northern England, 2017). Maintaining a significant amount of a variety of species, i.e. not just Sitka spruce. This is important to ensure diversity of species. (Red Squirrels Northern England, 2017) Ensuring a constant tree canopy that is not disturbed. To do this, the structure of the conifers will need to consist of stands of trees that are of a similar age. This will also help to reduce forest vulnerability to wind throw. (Red Squirrels Northern England, 2017) The lesser horseshoe bat, Rhinolophus hipposideros is also protected under the Wildlife (Amendment) Act 2000. As this species has such specific requirements i.e. needing dense vegetation to forage and linear sites to travel, it is given added legislative protection under the Habitats Directive (McAney, 2017). To protect this species, the woodland will firstly be surveyed to identify trees that contain roosts. This survey will be carried out in both summer and winter. This will be repeated every 5 to 10 years after this initial survey to evaluate any changes in the population (Foresty Commission , 2005). After surveying, a natural reserve will be created to provide security and permanency for the species. The careful management of the rest of the woodland is vital and will enhance the feeding areas of the bat species as well as other species present in the wood. The natural reserve will be monitored and reviewed every 5 years. (Foresty Commission , 2005) Objective Five: The final management objective that will occur in this woodland is the control of bracken encroachment. From the bassline study, a substantial amount of bracken was identified in the north-eastern part of the woodland. The presence of bracken is a sign of soil disturbance and will require a long-term management plan. Although bracken can be significant where it is mixed with other vegetation as well as providing an important larval food plant for some species of butterfly, its removal encourages primary habitats to re-establish which is of greater importance for wildlife. The complete eradication of bracken is not necessary nor desirable for this site, therefore the objective is to control the spread of bracken on a long-term basis for numerous reasons e.g. to protect other valuable habitats and vegetation (Farrell, 1999). Firstly, the presence of bracken should be identified and mapped by surveying its distribution between the months of July and October as this is when it is most visible. Then its vital to identify the target specific areas that need to be controlled and tackle the target areas first, i.e. those that are increasing rapidly. Initially the bracken will be controlled chemically, using a herbicide. The most common herbicide used is asulox which is favoured over roundup as it is specific towards certain plants e.g. ferns (Farrell, 1999). The site will be sprayed using a portable knapsack sprayer from the middle of July to August where weather is not too windy or wet, and a dye will be used to identify the fronds that have been treated. Spraying doesnt have any direct effects on the surrounding animals or to human health, however it will affect the taste of the bracken, thus all grazing animals will be fenced off for at least two weeks (Farrell, 1999). This treatment is expected to remove 98% of the bracken present in the area, however the other 2% will re-establish on the land over the following five years if an appropriate follow up plan is not prepared. This site will require a ten-year management plant which involves the continuous monitoring and treatment of the site. Initial spraying needs to be followed by cutting every 2-3 years for the foreseeable future (Farrell, 1999). Its important that a period of at least two years is left in between spraying. This is to allow buds that are dormant on the remaining bracken rhizomes to develop (Roberts MacDonald, 2017). Bracken encroachment can also be controlled by sowing heather cuttings, as the regeneration of heather is an excellent way to keep the encroachment of bracken under control. There will also be a period where animals cannot graze allowing new vegetation to grow from regeneration (Roberts MacDonald, 2017) References Betts, A. Ellis, J., 2009. So, you own a woodland?, Bristol: Forestry Commission National Office . Edwards, C., 2006. Managing and controlling invasive rhododendron, Edinburgh: Forestry Commission. Farrell, F., 1999. Bracken Management. [Online] Available at: http://www.esatclear.ie/~fionafarrell/html/technical_writing.html[Accessed 10 March 2017]. Forest Service , 2009. Forestry and Otter Guidelines, s.l.: Department of Agriculture, Fisheries and Food . Foresty Commission , 2005. Woodland Management for Bats , s.l.: Forestry Commission for England and Wales . Kent Wildlife Trust, 2017. Woodland management control of rhododendron and cherry laurel. [Online] Available at: http://www.kentwildlifetrust.org.uk/sites/default/files/kwt_land_mgt_advice_sheet_9_-_woodland_management_-_control_of_rhododendron.pdf[Accessed 10 March 2017]. McAney, D. K., 2017. Vincent Wildlife lesser horseshoe bat (RHINOLOPHUS HIPPOSIDEROS). [Online] Available at: http://www.mammals-in-ireland.ie/species/lesser-horseshoe-bat[Accessed 27 February 2017]. Red Squirrels Northern England, 2017. Habitat Management in Red Squirrel Reserves and Buffer Zones in Northern England. [Online] Available at: http://rsne.org.uk/sites/default/files/Habitat%20Management.pdf[Accessed 27 February 2017]. Roberts, J. MacDonald, A., 2017. Bracken Control. [Online] Available at: http://www.snh.org.uk/publications/on-line/advisorynotes/24/24.htm[Accessed 10 March 2017]. Stephens, P., 2005. Managing woodland open space for wildlife, s.l.: Forestry Commission England.