Centre for North-West Regional Studies HIMALAYAN BALSAM Impatiens glandulifera: A CASE-STUDY IN THE RYDAL LOCALITY - THE CONTROL AND PUBLIC AWARENESS OF THIS NON-NATIVE, INVASIVE PLANT. Sarah Colyer Sarah Colyer is a senior lecturer at the University of Cumbria, Faculty of Education. For over ten years she has been a member of the Cumbria National Trust Volunteer Group. During this time they have undertaken a number of projects to eradicate or control the spread of Himalyan balsam. Sarah studied with the CNWRS and was awarded an MA in Lake District Studies in 2010. In the summer of 2006 a survey was undertaken by the Lake District National Park Authority (LDNPA) which looked at the spread of Himalayan balsam, Impatiens glandulifera, within the Rydal, Grasmere and Ambleside parishes. A number of volunteers were engaged in the collection of this data, and the area personally surveyed centred round Rydal Water. The aim of this consequent study was to resurvey the same area after three years had elapsed and consider the following specific issues which had been identified within the research: Had the growth of Himalayan balsam spread since 2006? How much knowledge or awareness of Himalayan balsam did the surrounding community have? Had control measures had any impact? What had been the cost implications? Was it viable to continue this work in other areas of the Lake District? In the early 1990s a number of research papers appeared on the topic of Himalayan balsam and its spread across areas of the British Isles and Europe. However, there appeared to be little information on the Lake District. The Rothay Valley Sustainable Environment Group (RVSEG), formed in 2007, had been actively involved promoting awareness and co-ordinating volunteers in the locality of the study. Other than this, the tackling of the non-native, invasive species, Himalayan balsam, appeared to be on an ad-hoc basis in isolated areas. The research project considered the efforts undertaken to control Himalayan balsam within
the Rydal area and proposed recommendations for widening this project to other areas of the Lake District. Background What is a non-native invasive species? A native plant is one which occurs naturally in an area, this is often qualified by the addition of a cut-off date e.g. since 1600. A non-native therefore is a species that has not arrived naturally but has been helped by outside influence. In the Executive Summary of the National Invasive Species Management Plan the term invasive species is defined as an alien species that is non-native to the ecosystem under consideration and whose introduction causes or is likely to cause economic or environmental harm or harm to human health. 1 This definition captures the meaning of invasive species however the term alien is emotive and should be used carefully. Rotherham states not all aliens are problems, and not all problem plants are aliens. 2 CABI (2009), summarises for a species to be classed as an alien invasive, it must arrive, survive and thrive in its new environment. 3 Himalayan balsam has most definitely arrived, has survived and is thriving, not just in the Lake District but many parts of the UK, Europe and North America. 1 National Invasive Species Council, Invasive Species Definition Clarification and Guidance White Paper (2006), available at: http://www.invasivespecies.gov/global/isac/isac_documents/isac%20definititions%20white%20paper%2 0%20-%20FINAL%20VERSION.pdf (accessed: 9 th September 2009). 2 I.D. Rotherham, Loving the Aliens??!!? Journal of Practical Ecology and Conservation, Special Series, 4 (2005), p. 52. 3 G. Masters & L. Norgrove, Climate Change & Invasive Alien Species, CABI Working Paper 1 (2010) p.10.
Centre for North-West Regional Studies General description of Himalayan balsam Figure 1: Key identifying features of Himalayan balsam. Non-native species secretariat, photos from Olaf Booy, Mike Harris & Max Wade: www.nonnativespecies.org. (Photograph by permission: Olaf Booy, 2009). Himalayan balsam Impatiens glandulifera Reproductive Strategy Seed production varies with density of the plants, as the density increases the seed production per plant decreases. In Britain medium sized plants growing at a density of 20m -2 produce between 700-800 seeds, each pod containing between 4-16 seeds. 4 Seeds are released explosively when the fruit opens. The explosive character is a result of tensions set up by turgor in the fleshy fruit wall and seeds can spread up to 5 m, depending on the height of the capsule above the ground and the direction and strength of the prevailing wind during dehiscence. 5 Germination occurs in the second half of March and first half of April; the cotyledon stage lasts until early April and this is followed by very rapid shoot extension and leaf expansion. Flowering takes place from around the end of June and continues until the first severe frost or 4 D.J. Beerling & J.M. Perrins, Impatiens glandulifera Royle, Journal of Ecology, 81 (1993), p.376. 5 Beerling & Perrins, Impatiens glandulifera Royle p. 376.
through to October with seeds set from mid-july. The onset of flowering will be delayed by 2-3 weeks in shaded areas. 6 The plant in Britain 1839 is the widely recognised date for the introduction of Himalayan balsam into English gardens. 7 Seeds were sent to Kew by Royle from Kashmir in the western Himalayas. It was first recorded as a naturalized alien in 1855 in Middlesex. 8 From here it spread rapidly with reports of its existence in parts of Manchester and Lancashire by 1859. By 1898, less than 60 years since its introduction it was reportedly classified as a weed. 9 The scattered spread of Himalayan balsam in the British Isles from its original naturalization in Middlesex cannot be purely as a result of seeds escaping from gardens but must, in some way, involve human influence. Perrins, Fitter & Williamson note the appearance of the plant in County Durham in 1892 and in Cornwall in 1900; too soon after its first appearance in Middlesex to have been spread naturally. 10 Rotherham recounts a number of comments received from the general public regarding the spread of Himalayan balsam across the British Isles. 11 One lady collected seeds from the Sheffield area and released them along a river bank in the Isle of Wight in 1948. Another collected a sample from the Isle of Skye and took it to her parents house in Leicestershire in 1961, and in the 1990s seeds were collected from Snettisham in Norfolk for a lady s cottage garden in Belsay, Northumberland. 12 It is clear from these examples that people find Himalayan balsam aesthetically pleasing. While this is the case and people respond in this way, any attempt to control its spread is likely to have limited success. 6 J. Perrins, A. Fitter & M. Williamson, Population Biology and rates of invasion of three introduced Impatiens species in the British Isles, Journal of Biogeography, 20 (1993), p. 40. 7 C. P. Wheater, Urban Habitats (London, Routledge. 1999) p. 91. 8 J. Perrins, A. Fitter & M. Williamson, Population Biology and rates of invasion of three introduced Impatiens species in the British Isles, Journal of Biogeography, 20 (1993) p. 33. 9 Ibid, p.33. 10 Perrins et al., Population Biology and rates of invasion. p.40. 11 Rotherham, Loving the Aliens??!!?. p. 69. 12 Ibid, p. 69.
Centre for North-West Regional Studies Himalayan balsam in the Lake District Himalayan balsam was first recorded in Cumbria in 1921 by G.A.K. Hervey in Buttermere. 13 Patches appeared in the Lake District in the early 1930s; at Rydal, Glenridding and along the banks of the River Kent between Levens and Sedgwick. By the 1960s it had spread rapidly and was classed as a menace to other riverside plants. 14 Control of Himalayan balsam in the Lake District A number of separate projects tackling Himalayan balsam have taken place in the Lake District. The South Cumbria Rivers Trust (SCRT) is particularly active in the Kent catchment area as Himalayan balsam has colonised some large areas of the river Kent, especially in the slow flowing sections of the river around Kendal. Of particular interest to this study was the work of the Rothay Valley Sustainable Environment Group (RVSEG). This group was founded in 2007 and came about as a result of the publication of the Lakes Parish Plan and the need to address the growing invasion of Himalayan balsam, Japanese Knotweed, Fallopia japonica, and grey squirrels, Sciurus carolinensis, in the parish. It was felt that a co-ordinated approach was needed to tackle these invaders. The group included representatives from the National Trust (NT), SCRT, the Environment Agency (EA) and a group of keen local volunteers acting as co-ordinators covering Grasmere, Rydal, Ambleside and Troutbeck. One of the key aims of this research project was to evaluate the level of awareness in the surrounding area and consider how effective the RVSEG and other organisations had been in controlling the spread of Himalayan balsam. A mapping survey locating Himalayan balsam had been conducted in 2006 around the Rydal area and an updated survey, carried out three years later, provided data to consider how successful any measures had been to control the spread of or eradicate this invasive species. In order to assess the public s awareness of the impact Himalayan balsam had on the environment a simple questionnaire survey was carried out with residents in the surrounding area. In order to improve 13 G. Halliday, A Flora of Cumbria. (Lancaster, CNWRS, 1997) p. 332 14 G.A.K. Hervey & J.A.G. Barnes, Natural History of the Lake District. (London: Frederick Warne & Co., 1970), p. 7.
the reliability of the data it was decided to gather this information by the means of a very brief interview. This would avoid respondents guessing at the identification of Himalayan balsam and thus improve accuracy of data. The face-to-face approach not only improved the reliability of the data being collected but also gave an opportunity to raise further awareness of the invasive nature of this plant. Mapping Surveys Results and Analysis The original 2006 survey revealed there was 27,038 m 2 of Himalayan balsam growing in the three parishes of Rydal, Grasmere and Ambleside. Since that initial survey 18,729 m 2 had been removed before 2009. The area around Rydal Water and White Moss contained an estimated maximum of 21,140 Himalayan balsam plants in 2006. Three mapping surveys were conducted between April and August 2009. These showed the number had been significantly reduced to levels that should allow for successful control in the future. The final survey in August showed numbers to stand at an estimated maximum of 312 plants, this being a 98.7 per cent reduction. Alongside the surveys, a considerable amount of volunteer time was spent pulling balsam in a variety of locations. Figures 2 and 3: Volunteers systematically clearing HB at White Moss common and Calgarth Park, (Colyer, 2009).
Centre for North-West Regional Studies One specimen sample was kept as its rate of growth had been monitored over the preceding month. It was agreed with National Trust, (the landowners), that this would be removed before seeding. The plant was located under the shade of a very large fir tree. Between 3 rd April and 29 th April, the specimen had grown from 5 cm in height to 10 cm, a slower rate of growth to other Himalayan balsam plants in the vicinity which were not in the shade. Figure 4: Specimen of Himalayan balsam, recorded 3 rd April 2009 (Colyer, 2009)
Figure 5: Specimen of Himalayan balsam, recorded 13 th May 2009 (Colyer, 2009) On the 13 th May, the specimen was photographed and height recorded at 13 cm (see Figure 5). By the 2 nd June the specimen had grown to a height of 33 cm. It had taken more than 42 days to grow the initial 13 cm but only 18 days to grow a further 20 cm. This data supports that of Beerling & Perrins who claimed, the cotyledon stage lasts until early April and is followed by rapid shoot extension and leaf expansion. 15 However, whilst this study would agree that a rapid shoot extension and leaf expansion took place, there appeared a period of delay between the initial seed leaf and the rapid growth, something not recorded by Beerling and Perrins. Unfortunately at some point between 2 nd June and 10 th July, when the next opportunity arose to take a measurement, someone had removed the specimen; but perhaps proof that at least one member of the public was aware of the invasive nature of this plant and doing something to help control its spread. The second survey covering the extended area around Rydal Water was completed on the 13 th July 2009. This showed that although all evidence of Himalayan balsam was believed to be removed during the May work party at White Moss Common, small amounts still remained and a few significant areas of over 100 plants were present. It is impossible to state categorically if the plants recorded on the second survey were present at 15 Beerling & Perrins, Impatiens glandulifera Royle, p. 375.
Centre for North-West Regional Studies the time of the first survey but missed when the working party cleared the area, or whether these were from seeds that had germinated since the clearance. Germination occurs in February-March according to Beerling & Perrins. 16 However, Perrins, Fitter & Williamson state that in their experiments the seeds germinated during the second half of March and first half of April. 17 As there were some significant areas containing more than 100 plants and in two places in excess of 500 plants, it is possible that at least a large proportion of these seeds had not germinated by 17 th May. This is considerably later than dates given by Beerling and Perrins in 1993. The final survey was completed on 21 st August 2009. Seed pods had fully developed on many of the plants by this point in time (see Figure 6); thus rendering their removal pointless as the seeds would explode on touching the plant. Figure 6: Seed pods fully developed on Himalayan balsam, (Colyer, 2009) The results of the final survey show significant reductions in the number of Himalayan balsam plants present within certain areas and total eradication in other locations. Only two locations remained where the 16 Ibid, p. 375. 17 Perrins et al., Population Biology and rates of invasion, p. 40.
number of plants recorded was between 10 and 100. In some areas, for example the land south of the A591 and to the west of the car parks at White Moss common, (grid ref. SD 348,064) all evidence of Himalayan balsam had been successfully removed. This also applied to the land (grid ref. SD 357,063) close to Nab Cottage. In the original survey conducted in 2006, numbers were recorded at approximately 8,000 in total on this site. In July 2009 just nine plants remained and these were all removed before seeding. In August 2012 there was still no evidence of the plant growing on this land. The RVSEG produced statistics in 2008 showing what impact volunteers and contractors had on both Himalayan balsam and Japanese knotweed in the Rothay Valley. It concluded that 18,729 m 2 of Himalayan balsam had been pulled or strimmed at a cost of 1,351.25 or 7 p/m 2. However, it was estimated that in addition to this 575 hours of voluntary work had been conducted at no extra cost. Volunteer hours in 2008 and 2009 increased that total considerably; nonetheless the surveys confirm that the eradication or control of Himalayan balsam has been proved possible. Figure 7: No evidence of Himalayan balsam, White Moss Common (Colyer, 2012) Questionnaire Survey Himalayan balsam Questionnaire Survey Results and Analysis Fifty brief questionnaire surveys were undertaken to ascertain the general public s awareness of Himalayan balsam in the local area. The survey contained five closed questions:
Centre for North-West Regional Studies 1. Have you heard of Himalayan balsam? 2. Do you know what it is? 3. From the three pictures can you identify which one is Himalayan balsam? 4. Do you have it on your land or garden? 5. As a non-native invasive species, would you be prepared to remove it to stop its spread? Although all the answers were recorded and analysed as a simple yes or no, comments were also noted allowing additional reflection on the findings to be made. Results & Analysis Question 1: Q1. Have you heard of Himalayan balsam? Yes - 21 No - 29 Figure 8: Questionnaire survey, question 1 data Question 2: Q2. Do you know what it is? Yes - 16 No - 34 Figure 9: Questionnaire survey, question 2 data
While 42 per cent had heard of Himalayan balsam only 32 per cent actually knew what it was. 68 per cent either had no knowledge at all, or only a vague recollection of hearing the term. Questions 1 & 2 at first glance may appear to ask for the same information but as the results showed, there is a distinction. This is important if ascertaining a true indication of the actual level of knowledge and understanding of this plant by the local community. Additionally, this was one of the aims of the RVSEG; to raise awareness of particular invasive species with local people and landowners. Splitting the information into two questions helped assess this. Comments made when answering question 2 included: Is it something you rub on your skin?, Is it wood?, Is it like Himalayan Knotweed? All showed some level of confusion or misunderstanding. Question 3: Pictures of three different types of balsam were shown to each interviewee: 1) Himalayan balsam Impatiens glandulifera 2) Small balsam Impatiens parviflora 3) Touch-me-not balsam Impatiens noli-tangere.. (These were not labelled, see Figure 10 below)
Centre for North-West Regional Studies Figure 10: 3 photos of different balsam shown to interviewees (Colyer, 2009)
Each was asked if they were able to recognise Himalayan balsam, rather than taking a guess. Only 16 per cent were able to identify the plant. Surprisingly, 50 per cent of those who had heard of it and were already knowledgeable about its invasive nature were unable to actually identify it; most that fell into this category said if they had to guess they would have chosen the picture of Small balsam. This clearly highlights that whilst there had been some success in raising awareness of this plant, more publicity was needed if control or eradication of this species was to be effective. Question 4: Q4. Do you have it on your land? Yes - 4 No - 46 Figure 11: Questionnaire survey, question 4 data Only eight per cent had it growing in their garden and all these had water running through or along the boundary of their land. This is not surprising as research has already identified that it thrives along river banks, stands over 100 m long are common along the river banks I. glandulifera is widespread in riparian habitats... most commonly 0.5 and 3 m above the water level of the river. 18 18 Beerling & Perrins, Impatiens glandulifera Royle, p. 367.
Centre for North-West Regional Studies Question 5: Q5. As a non-native invasive species, would you be prepared to remove it to stop its spread? Yes - 45 No - 5 Figure 12: Questionnaire survey, question 5 data Although the majority of people surveyed could not recognise Himalayan balsam, 90 per cent were very willing to help control its spread. Of the five people who would not remove it, two said they would contain it within a small area of their garden, two said it looked pretty and did not see why it should not be left to grow and the other admitted to not being a gardener and was happy to have anything growing on his land, especially something that pretty. Rotherham raised the issue of the public liking this plant as it is aesthetically pleasing. 19 Many of those surveyed also commented on this aspect. In their ignorance about its invasive nature why would they want to see it removed? It is clear that recognition and knowledge are both needed if the public are to help control the spread of Himalayan balsam. Identification information sheets need to be widely available to help educate the public. Conclusion and Recommendations This project set out to explore five specific issues: 1) Had the growth of Himalayan balsam spread since 2006? The results of the mapping surveys covering the case study area show the answer to be an emphatic no. However, from personal observations and work undertaken at the additional location of Calgarth Park, it is clear that Himalayan balsam has spread rapidly in other areas over recent years and now dominates large sections of the banks down to Windermere. The concern here being that if seeds get into the beck and then flow into the lake their dispersal could possibly cover a huge area 19 Rotherham, Loving the Aliens??!!? p. 65.
CeNtre WoRdS No 11, 2012 as the perimeter of the lake measures approximately 22 mi. The Leven flowing out of Windermere could also be affected. Taking it one stage further, the Leven flows out into Morecambe Bay and the Irish Sea so potentially seeds could travel vast distances. This scenario would support the findings of Perrins, Fitter and Williamson who found that seeds of Himalayan balsam could spread up to 38 km yr -1. 20 Further research would be needed to examine how long seeds could survive in fresh water or sea water in order for this scenario to have any validity. 2) How much knowledge or awareness of Himalayan balsam does the surrounding community have? Outcomes of interviews showed that awareness of Himalayan balsam and its impact on the environment was very low. 84 per cent could not identify the plant from the choice of three pictures and only 32 per cent knew what it was. It is acknowledged that this is a very small scale piece of research with only 50 people being interviewed and therefore has some limitations. A larger pool may possibly produce different results. Although those working in the field of conservation, or those with a keen interest in it, will be undoubtedly very familiar with the invasive nature of this plant, the general public still lack that awareness. The above findings were discussed at a conference on Exotic and Invasive Plants and Animals held at Sheffield Hallam University and caused some alarm that public awareness was this low. Many members of the public still see a pretty, orchid like flower growing by the roadside or along the river banks which is more aesthetically pleasing than some other species. The responses to the final question show overwhelmingly that if awareness is raised then people would be prepared to help control the spread of this plant. Some form of poster campaign needs to be implemented for a positive effect, as the ability to identify the plant is lacking at present. Additional information boards on NT or LDNPA land are a possible way of increasing awareness and identification. The NNSS have very useful ID sheets available on their website (see Fig.1). 20 Perrins et al., Population Biology and Rates of Invasion p. 40.
Centre for North-West Regional Studies 3) Have control measures had any impact? Within the surveyed area control measures had undoubtedly worked but these can still be improved. Whilst surveying for this research any small pockets of Himalayan balsam were removed wherever possible. Small piles of pulled balsam were also noted proving that at least one other person was removing it from the surrounding area. The total number of hours involved cannot therefore be measured accurately but should not be underestimated. Control of this plant has relied on the continued efforts of a few volunteers and will continue to rely on these people in the future, if publicity is not increased. The final survey showed small amounts of Himalayan balsam still remained in the area and previous research has proved that seeds can remain dormant in the soil for at least 18 months before germinating. In order that the hours previously spent, estimated at over 700, are not in vain continued surveillance and pulling is essential to control or eradicate this species. As each plant can contain up to 800 seeds, one solitary plant could easily be responsible for negating many hours of labour. As a recommendation, once an area has been cleared, a designated person would still be needed to survey each year, to ensure that no new plants appeared. 4) What have been the cost implications? The use of volunteers kept the financial cost incurred in this particular case study low. 1,351.25 was recorded by RVSEG in 2008, which covered a much larger area than this particular study. In addition, however, there are the costs of LDNPA rangers and NT rangers who have led work parties in the area. Should this be expanded to other parts of the Lake District the co-ordination and expenditure necessary would be greatly increased if eradication or control is to be realised. However, well managed co-ordination could, in the long term, provide a significant decrease in time, effort and, hopefully, cost. 5) Is it viable to continue this work in other areas of the Lake District? Yes, but certain considerations need to be examined beforehand. A weakness in this research was unfortunately in the chosen location. It was conducted here as a previous survey had already been completed by the researcher and a number of work parties had been carried out providing evidence to make an objective study. The area is, however,
CeNtre WoRdS No 11, 2012 located part way along the course of the River Rothay and there is known to be Himalayan balsam growing further up the valley. This needs investigation and control in the future if the work on this project is not to be in vain. Yet again, it highlights the essential need for careful co-ordination across the Lake District if this invasive species is to be tackled successfully. The success of any further projects has to rely on landowners being knowledgeable and willing for Himalayan balsam to be removed from their land. It is illegal under the Wildlife and Countryside Act (1981) intentionally to uproot any plant from the wild without the permission of the landowner. Once landowners are in agreement then ideally large numbers of volunteers, or contractors, are needed in the initial stages to remove or control the expanses of Himalayan balsam increasingly evident in other parts of the Lake District. Finally, as already outlined above, individuals would need to be assigned to particular areas to control any future spread. The Future If work is not undertaken, the future landscape of the Lake District could look very different. Continued spread of Himalayan balsam would result in river banks being eroded at an increased rate during winter; due to a lack of any root system to hold the soil in place. The fast-growing nature of this non-native species prevents shorter native plants from getting enough light to grow underneath. By winter only hay like remains of the balsam are left, leaving the ground looking very barren. The abundance of seeds contained in explosive pods would result in an ever increasing acreage of Himalayan balsam to the detriment of native plants. However, change is constant and the Lake District today looks very different to the Lake District of years gone by. Do we now have a cultural landscape rather than a natural landscape and if so, who is to say what our landscape should look like in the future?