The Ecosystem Benefits of managing

the invasive non–native plant

Rhododendron ponticum in

Snowdonia

Snowdonia Rhododendron Partnership

2015

Rhododendron in Snowdonia

A plant native to areas of the middle-east and Mediterranean countries, it is thought that

Rhododendron ponticum was first introduced to the UK as an ornamental plant during the in

1763 (Cross, 1975). However, it soon became established in the wild, with the rate of spread

accelerating in the latter half of the 20th century. This is possibly as a result of changes in land

use, increased grazing pressures and a reduction in rabbit populations as a result of

myxomatosis. It has been suggested by some that the plants spread has become stable, although

it remains an aggressive plant in certain areas and on certain habitats.

As to why certain areas are affected worse than others, the reasons aren’t entirely clear.

However, genetic analysis of Rhododendron suggests that British populations often contain the

genes of Rhododendron catawbiense, a North American species, which may confer greater cold

tolerance and therefore allow it to colonize colder parts of Britain. However, it is not known if

this applies to Rhododendron in Snowdonia.

Why we wish to eradicate Rhododendron ponticum

Whilst it may be difficult to argue against the aesthetic attractiveness of the plant when it’s in

bloom, the negative impacts of Rhododendron far outweigh the positive aspects of its presence.

Invasive species have been identified as one of the major drivers of ecosystem degradation in

Wales (UK National Ecosystems Assessment, 2011), and cost the Welsh economy approximately

£7 billion per annum (National Assembly for Wales, 2013). Furthermore, invasive non-native

species (INNS) are listed as the second biggest threat to native wildlife globally after habitat

loss. Whilst it’s impossible to break the cost/threat posed to individual species and/or areas,

much of this cost derives from the impacts of INNS on the ability of natural ecosystems to

function properly, resulting in degradation to key ecosystem services.

Due to its ability to out-compete, smother or shade native species, it has had severe detrimental

impacts to many of our natural

habitats. By now, it is widely

regarded as one of the main

invasive non-native species

(INNS) present in north-west

Wales, with an estimated area

of over 2,000 ha now infested

by Rhododendron within the

National Park (SNPA, 2008).

Area behind Beddgelert which has been cleared of Rhododendron ponticum (2014)

What are ecosystems and ecosystem services?

An ecosystem can be defined as a community of living organisms (biotic factors), which in

conjunction with the physical environment (abiotic factors), function together in a given area of

the environment. The benefits that humans derive from ecosystems are often referred to as

ecosystem services. These can range significantly, but can be grouped into four broad

categories; provisioning, regulating, cultural and supporting services (Millennium Ecosystem

Assessment, 2005). They are defined as follows:

Provisioning services are the products obtained from ecosystems. In Snowdonia, these

would be such things as food, timber and peat;

Regulating services are the benefits obtained from the regulation of ecosystem

processes, such as regulation of climate, water, pest and diseases;

Cultural services are the non-material benefits people obtain from ecosystems through

recreation and aesthetic pleasure;

Supporting services are ecosystem services that are necessary for the production of all

other ecosystem services. Examples include biomass production, nutrient and water

cycling, and the conservation of natural habitats.

Annex I shows the level of impact Rhododendron infestation has on a wide variety of

ecosystems services in Snowdonia. Some of the key impacts include:

Soil quality – it has long been said that Rhododendron ponticum has adverse impacts on

soil health, a key ecosystem service. These include increased soil acidity and a decrease

in biodiversity essential for maintaining soil health e.g. earth worms (UK National

Ecosystems Assessment, 2011).

Pollination – species such as heather provide a valuable source of food for our native

pollinator species. By decreasing the availability of food sources to pollinators,

populations will decrease, as has been witnessed in recent years. Indeed, according to

the Welsh Government, habitat loss is one of the main reasons for the decline in native

pollinators in Wales (The Action Plan for Pollinators in Wales, 2013);

Disease and pests – whilst Rhododendron itself can be considered a pest, its ability to

host other diseases and pathogens such as Phytophora, thus facilitating their movement

in the wider landscape, is of great concern. Such pathogens pose a threat to both native

and commercial woodlands, both of which are vitally important in terms of their

ecological and commercial values in Snowdonia;

Primary productivity – this includes food production (both livestock and crops), timber

production and wild fish stocks, all of which are essential in supporting the local

economy in Snowdonia. Due to its highly invasive nature, Rhododendron infestation will

make otherwise suitable habitats unsuitable for grazing animals, thus reducing the

amount of land available to farm.

As we all know, Snowdonia is blessed with a rich diversity of habitats, which in turn support a

rich array of plants and animals. Collectively, they are referred to as biodiversity, and include

everything from the tiny micro organisms found in soils and waters to large plants and all the

creatures which call Snowdonia their home. Basically, it’s all living things!

As a non-native invasive plant, Rhododendron ponticum would not have grown naturally in

Snowdonia had humans not introduced it. As mentioned above, its infestation can have dramatic

impacts on the native habitats of Snowdonia, primarily habitats of the uplands (moorlands and

heath), our native woodlands, unimproved or semi-improved species rich grasslands and

freshwater habitats. Specific impacts on each key habitat are discussed below.

Moorlands and Heath

Snowdonia National Park and the surrounding regions are defined by upland habitats, where

both moorland and heathland is widespread in areas such as the Migneint, the Berwyn

Mountains and Mynydd Hiraethog, all of which are protected under either national or European

law due to their ecological importance. Whilst the majority of these habitats are to be found in

upland areas, they can also be found on hillsides between enclosed farmland and the open

mountain (often referred to as Ffridd in Wales), and even in lowland areas such as Arthog Bog

on the Mawddach Estuary. Such habitats provide a wide and diverse range of ecosystem

services, as listed in Figure 1.

Rhododendron encroachment into upland habitats can have drastic impacts on the ecosystem

services we derive from them. Whilst altitude is thought to be a limiting factor in the spread of

Rhododendron into upland areas (very few bushes have been recorded above 400m), its ability

to withstand wide climatic variation and a tolerance to a range of substrates means it can grow

almost anywhere where there is sufficient moisture (Snowdonia National Park, 2008).

Due to its ability to withstand a wide range of environmental conditions, Rhododendrons is able

to outcompete many native plants, having knock-on impacts on associated fauna and resulting

in decreased ecosystem functioning. The dense shade produced by Rhododendron canopies

leaves little light penetrating through, thus associated flora, even shade-loving bryophytes, or

their associated fauna, are minimal. Furthermore, studies show that few species of invertebrates

utilise Rhododendron as a food plant (Judd and Rotherham, 1992). Consequently there is little

to threaten rhododendron’s expansion and food chains based on Rhododendron are likely to

have low biodiversity value. Considering that biodiversity is widely regarded as a key

supporting service, essential for the healthy functioning of all other ecosystem services whether

they be provisioning, regulating or cultural, this can only be a bad thing.

An example of this would be Rhododendron encroaching into heath land, suppressing the

growth of native plants such as heather, thus diminishing a vital food source to local pollinator

populations. Another example would be the growth of Rhododendron on bogs and mire. If dense

stands are allowed to form, this will be to the detriment of bog forming mosses such as

sphagnum spp. These mosses provide a range of ecosystem services such as retaining and

filtering water, and peat formation. Furthermore, in abundance, Rhododendron growth could

essentially dry out wetlands, making the underlying peat more susceptible to oxidisation.

Ultimately, the carbon stored in peat would be released into the atmosphere, contributing to

global warming rather than helping to mitigate it.

As alluded to above, the uplands define Snowdonia as we know it. Indeed, it’s this diversity of

landscapes and their ever changing colours throughout the seasons that attracts millions of

visitors to the area each year. This makes tourism one of the main economic drivers in

Snowdonia. It is difficult to believe that anyone would welcome a change from the diverse

tapestry of native habitats we have in our landscape to one dominated by Rhododendron.

Whilst some might argue that Rhododendron in bloom is itself a site worth seeing, it’s important

to remember that the plant flowers for only a short time period, and that for the rest of the year

it provides nothing but a monotonous green carpet on what would otherwise be a varied and

colourful landscape, changing throughout the seasons.

Along with grasslands, heathlands are one of the richest habitats in respect of flowering plants

and of the 472 species found there, around one in four are threatened (State of Nature Report,

2013). Many of the species are often locally distinctive, thus their genetic make-up could differ

drastically to other areas of the UK. The maintenance of genetic diversity is critical in view of the

increased threat from climate change, and is needed in order to facilitate successful restoration

and conservation projects (National Ecosystem Assessment, 2011).

Service Description

Livestock Meat from grazing animals (primarily sheep and some beef cattle in Snowdonia) and fibre (wool)

Peat Upland soils are amongst the most carbon rich in the world

Wild game Traditionally, large areas of the uplands were managed for wild game

Genetic resources Heathland are amongst some of the most species rich habitats

Energy From hydro-electric and wind energy power schemes

Water Over 80% of our water supplies comes from upland areas

Pollination Heathland amongst most diverse habitats in terms of flowering plants

Water quality Moss rich bogs act as a natural water filter

Water regulation Upland habitats have the ability to store large amounts of water, thus reducing risk of flood and providing a steady source during times of drought

Climate control By conserving carbon rich soils and carbon sequestration potential

Disease regulation By hosting such pathogens as phytophthora and ticks (lime disease)

Regulation of pollutants

Intercept both water borne and air borne pollutants and pH buffering

Cultural heritage The uplands define Snowdonia as we know it a historical landscape with archaeological features that are degraded/damaged by rhododendron

Human well-being Derived from being outdoors (both mental and physical)

Tourism and recreation Varied landscape of Snowdonia attracts millions of visitor annually

Education Upland habitats provide a range of education opportunities

Biodiversity Required for the maintenance of healthy ecosystems

Soil formation, nutrient and water cycling, oxygen production

Forests facilitate all these things, essential for the maintenance of healthy ecosystems and indeed, life itself

Figure 1. Main ecosystem services derived from upland habitats

The main benefits derived from controlling Rhododendron ponticum on moorlands and heath

lands in Snowdonia are:

Increasing the area of native flora for the benefit of biodiversity, including pollinator

species, within the National Park;

Decreasing the risk of spread of pests and diseases in the wider environment;

Ensuring that wetlands such as blanket bogs remain in favourable condition and thus

continue to provide associated ecosystem services in relation to water retention and

quality;

Bringing land back into agricultural production;

Improving access to the countryside to the public and making the area more

aesthetically pleasing.

Woodlands

Snowdonia is renowned for its vast variety of woodlands, from the ecologically rich Atlantic oak

woods of Meirionydd, full of mosses, liverworts and lichens, the mixed ash woods of the Nant

Gwynant valley and areas of wet woodland dotted around the Park. As with heaths and bogs,

many of these are designated due to their high conservation value. It is also worth remembering

that it isn’t only our native woodlands that are under threat from Rhododendron, but also

commercially planted coniferous crops such as those found at Gwydir Forest, Coed-y-Brenin

and the Dyfi Forest.

It is fair to say that the relationship between Rhododendron and woodlands is not a good one.

Due its ability to produce a dense canopy layer and grow in well shaded areas, Rhododendron

will more than likely out-compete the natural regeneration of trees in woodlands, particularly

lower plants such as bryophytes and lichens. If left untreated, the Rhododendron bushes will

eventually form a thick blanket in the under storey, and as mature trees die, the woodlands will

ultimately be replaced. This is a particular problem amongst light demanding tree species, such

as oaks and birches. Unfortunately, it is not entirely clear what the full impacts of

Rhododendron are on the natural cycle of woodland regeneration due to no such studies being

taken (as far as we’re aware). This is primarily due to the length of time it takes for a

Rhododendron stand to mature and then die back. Whilst it may be the case that stands will

eventually die back and offer opportunities for native species to re-colonise, the longevity of

Rhododendron means that such benefits would not be observed for centuries, and the shorter

term damage far outweighs any potential opportunities for re-generation in the future.

It is not only the above ground organisms that suffer as a result of Rhododendron infestation.

For example, mycorrhizas, which are a community of soil fungi that form symbiotic (mutually

beneficial) relationships with the roots of plants, will decrease in line with reduced diversity of

plant species. Whilst some mycorrhiza form beneficial relationships with Rhododendron (thus

facilitating its growth) others are adversely impacted, especially those associated with native

woodlands. Consequently, woodland ecosystems that are dependent on these unique

relationships between native trees and mycorrhizas for healthy functioning suffer and therefore

any threat to this vital relationship is potentially critical.

Rhododendron ponticum is also known to host pathogens

such as Phytophthora ramorum (DEFRA), a pathogen

which is a great threat to conifers, notably larch and to our

native broadleaf woodlands and to heathland species i.e.

bilberry (Vaccinium myrtillus). As a host, Rhododendron is

likely to facilitate the spread of such pests in the wider

countryside. Unfortunately, Phytophthora does not

seriously threaten Rhododendron’s survival.

Consequently, its elimination will dispose of one of the

major pathways for the spread of Phythophora and other

diseases. In view of the increased threat posed from such

diseases as a result of climate change (Ray, 2008),

reducing potential pathways now is essential in order to

conserve ecosystems over the coming decades.

Furthermore, it may produce biochemicals which can

affect other plants, inhibiting the germination or seedling establishment of other species.

Rhododendron infestation in non-native commercial forestry plantations can also be highly

problematic when it comes to harvesting those crops. This is primarily due to issues relating to

access, as treatment of Rhododendron becomes increasingly difficult within dense woodland.

This will ultimately push up the cost of felling timber, sometimes adding tens of thousands to

forest operations. This has been witnessed firsthand here in Snowdonia in areas such as Coed yr

Eryr in Nant Gwynant. Rhododendron also makes the replanting or regeneration of these

plantations almost impossible as the stumps which are left behind are a huge issue in terms of

restricting access. Without whole stump removal, planting by both machine or by hand would

become very difficult, and the costs associated with such operations would increase

dramatically.

Service Description

Timber Both native woodlands and forest plantations are important sources of timber, used for a variety of purposes i.e. fuel, construction, pulp etc..

Genetic resources Having healthy, mixed species woodlands provides local genetic variability including the genetic resource of the component biota.

Water Heavily wooded catchments often provide water to wider communities and improving water quality.

Crops and livestock Woodlands sometimes facilitate livestock (agro-forestry) and provide non-timber products such as berries, honey, fungi and meat i.e. venison Woodlands also provide shelter and forage for livestock.

Water quantity

Regulating flood control by reducing the flow rate of water into the lower catchment during prolonged periods of rain; by creating a complex structure, woodland slow the passage of water to the rivers, aiding infiltration and ameliorating flooding . (McIntyre et al, 2008)

Air quality Trees produce oxygen, which is essential for life on earth, and capture atmospheric pollutants

Soil quality Can stabilise and thus protect soil from erosion

Pollination Provide habitat for diverse wild pollinator communities

Diseases and pests Associated fauna i.e. bats can help regulate the incidence and spread of insect pests

Climate control

By sequestering carbon (in soils and in the timber itself) Provide localised shelter to wild and domestic livestock during extreme weather

Environmental setting

Providing, amongst others things, an educational resource, recreational opportunities and a sense of place

Biodiversity Maintain a wild and diverse range of wildlife, often locally distinctive and adapted to those areas

Soil formation, nutrient and water cycling, oxygen production

Forests facilitate all these things, essential for the maintenance of healthy ecosystems and indeed, life itself

Figure 2. Ecosystem services derived from the woodlands in Snowdonia

The main benefits derived from controlling Rhododendron ponticum in the woodlands of

Snowdonia include:

Improve the diversity of flora associated with native woodlands in Snowdonia;

Allow for forest operations such as felling to be undertaken more efficiently, thus

reducing costs;

Reduce the risk of spread of pests and diseases within woodlands (both native and

plantations);

Make for healthier and more resilient woodland ecosystems which in turn offer local

genetic variability;

Improve soil quality and decrease soil erosion;

Increase recreational opportunities within woodlands.

Semi-natural or unimproved grasslands

Semi-natural or unimproved grasslands are usually species rich when compared with areas of

improved grassland. Although not abundant in Snowdonia, those that are left offer a unique

habitat, not only rich in plant diversity, but also supporting an array of fungi and invertebrate

species. Furthermore, they provide valuable grazing land for livestock, which is required to

manage the encroachment of scrub and maintain the species rich vegetation found in these

habitats. Services provided by semi-natural and improved grasslands can be found in Figure 3.

Species rich grasslands have declined dramatically over the last few decades, with an estimated

97% loss in such habitats in the last 50 years (Check: David Stevens for Wales data)Pywell et al.,

2002). Whilst such habitats aren’t abundant in Snowdonia (owing primarily to the topography

of north-west Wales), it is vital that those remaining fragments are conserved due to their

scarcity. Whilst INNS has not traditionally been one of the main drivers in the decline of semi-

natural grasslands in the UK, it could pose an increased threat to these habitats in future years

should they go untreated (UK National Ecosystems Assessment, 2011).

Many of the impacts Rhododendron has on species rich grassland habitats are similar to those

associated with other habitats discussed previously. That is, due its ability to outcompete

natural vegetation associated with unimproved or semi-improved grasslands, Rhododendron

will eventually replace native species and compromise the ecosystems services they serve.

For example, Rhododendron encroachment into unimproved grasslands will essentially exclude

livestock (due to the density of the bushes), rendering them unsuitable for grazing livestock.

Furthermore, Rhododendron itself is also poisonous to cattle and sheep (Cooper and Johnson,

1984). Consequently, if left to spread, that

piece of land will essentially become

unproductive. This then leads to the loss

of species diversity, which will impact on

local populations of pollinators and so

on.... in addition, the loss of productive

land will lead to reduced agricultural

subsidies to farmers, which is obviously

never welcomed!

It is also worth mentioning the impacts of

Rhododendron on soil, as it is said that its

growth will have an acidifying impact in

areas in which it grows. However, there is

little scientific evidence out there to back

this up. What is perhaps a little more

apparent is the impact Rhododendrons

can have on earthworms, essential for the

maintenance of healthy soil. Although

unimproved or semi-improved grasslands

can be found on a range of soils

(calcareous, neutral or acidic), they are

often fairly productive free-draining soils

compared to those found in higher altitudes. Earthworms are an essential part of maintaining

healthy soil, and are also a vital food source to other species, primarily birds and small rodents.

Consequently, a decrease in populations could have dramatic impacts on local food chains and

soil health.

Service Description

Livestock Semi improved or unimproved grasslands require appropriate grazing to eliminate invasive weeds and maintain diversity, thus providing food (meat, milk) and fibre (wool)

Genetic resources

Less intensively managed grasslands are far more species rich than those which have been improved, thus they maintain a higher level of genetic resources

Biomass For silage or crops

Pollination Less intensively managed grasslands are far more species rich than those which have been improved

Climate Grassland soils are a reserve of carbon and other greenhouse gases

Water Increased vegetation cover will reduce surface water run-off , providing flood protection, and storing pollutants, particularly in riparian areas

Environmental settings

Protecting valued species and agricultural heritage and providing areas for recreational activities i.e. walking and educational visits

Biodiversity Required for the maintenance of healthy ecosystems

Figure 3. Ecosystem services derived from semi-improved or unimproved grassland habitats

The main benefits derived from controlling Rhododendron ponticum within the grasslands of

Snowdonia are:

Reinstating land which was previously unsuitable for grazing back into agricultural

production, primarily grazing and arable to a smaller extent;

Decrease the risk of illness/fatalities within livestock as a result of the ingestion of

Rhododendron litter;

Increase vegetation cover and therefore reduce surface run-off.

Freshwater habitats (lakes and rivers)

Whilst the threat of Rhododendron on freshwater habitats is perhaps less apparent than other

INNS such as Himalayan balsam (Impatiens glandulifera) and Japanese knotweed (Fallopia

japonica), it can nevertheless have severe harmful impacts these ecosystems.

Rhododendron will thrive in riparian areas, outcompeting native vegetation on river banks and

the shores of lakes and ponds. Whilst the loss of native vegetation in these areas will result in

many of the same impacts as in other habitats i.e. loss of food source to native pollinators, it can

also have additional adverse impacts in freshwater environments. For example, riparian

vegetation supports a diverse population of invertebrates, the main food source of some fish

species. Trout depend on invertebrates which live in riparian areas for up to 80% of their food

source. Rhododendron stands don’t support anywhere near the same level of invertebrates as

those of native vegetation, therefore decreasing the food source to fish populations significantly.

the lack of understorey associated with a stand of Rhododendron leaves soil bare and thus

susceptible to erosion during periods of heavy rain. Whilst this is true in other habitats, it’s

more of a problem on streams and rivers where the force of the water is able to erode far

quicker than surface run-off in fields or woodlands.

Erosion can have adverse impacts on water quality which in turn, impacts on local fish

populations. Often, such soils are rich in metals, and increased flow can wash such undesirable

elements into watercourses, altering the pH and chemical composition of freshwater habitats

and having significant adverse impact on local fish populations.

Furthermore, large scale erosion can also often lead to significant loss of land which would

otherwise be suitable for farming. This is particularly problematic along larger rivers and

during flash flooding events. The water that we use to drink and wash in comes from freshwater

habitats via reservoirs and water treatments works. The cleaner the water is reaching these

works, the easier it is to treat and, more importantly perhaps, less expensive and less damaging

to the environment.

The accumulation of dead Rhododendron litter is especially problematic in standing water such

as ponds and the edges of lakes. Such habitats are often rich in flora and fauna, supporting wild

fish stocks, invertebrates and a range of freshwater flora. Rhododendron leaves are notoriously

slow at decomposing, thus they are able to accumulate on the surface of standing water, forming

a thick, impenetrable film. Many of the plants which are affected in such circumstances are

natural cleansers of water, thus further contributing to the worsening of water quality within a

catchment.

Whilst discussing freshwater habitats, mention must be made to other habitats that are perhaps

not freshwater habitats in their own rights, but have a strong link to our rivers, ponds and lakes.

These include such habitats as floodplain wetlands, marshlands and fenlands. The ecosystem

services derived from these habitats vary massively, but would include such things as providing

land for grazing, removal of pollutants, flood control and climate control (through the

conservation of carbon rich peaty soils). They can also impact on manmade structures

associated with freshwater habitats, such as culverts. As Rhododendron leaves decay far slower

than that of native species, they can often accumulate in culvers and small channels, leading to

blockage. If this happens on a larger scale, it can lead to localised flooding of roads for example.

Figure 4. Ecosystem services derived from freshwater and associated riparian habitats

The main benefits derived from controlling the spread of Rhododendron ponticum on the

freshwater habitats of Snowdonia are:

Minimising the impact on riparian habitats and the flora and fauna they support;

Reduce the risk of contamination as a result of increased sedimentation;

Decrease soil erosion, which can impact on both water quality and lead to the loss of

agriculturally productive land.

Improve flood alleviation by slowing the flow of rainwater into catchments.

Service Description

Water Lack of understorey can lead to increased levels of riverside erosion

Wild fish In rivers, ponds and lakes

Farmed fish Similar to wild fish

Peat On adjacent habitats i.e. floodplains and bogs/marshes

Water quality Riparian habitat controls surface water run-off and reduces sedimentation levels

Water quantity Both river-flow and flood regulation

Human health Natural freshwater systems support physical recreation. Mismanaged freshwater habitats can be sources of water borne diseases and disease vectors

Environmental setting

Can provide a sense of place, defining specific landscapes

Tourism and recreation

Attracting fishing enthusiasts, naturalists and outdoor recreationists

Biodiversity Support a diverse range of species essential for maintaining ecosystem health i.e. spawning grounds

What we are doing

One of the main statutory purposes of all National Parks is to ‘conserve and enhance the natural

beauty, wildlife and cultural heritage’ of the area in which that respective National Park lies. The

spread of invasive non-native species poses a threat to all three of the above, as reflected by

Objective 5b of the Snowdonia National Park Management Plan 2010-15 (SNPA, 2010). This

states that the Authority will ‘continue efforts to reduce the land area covered by invasive

species’ within Snowdonia and its environs over the coming years. In order to achieve this

objective, Snowdonia National Park Authority have been working in partnership with other

relevant organisations, third sector nature groups and private landowners over the last decade

in treating vast areas blighted with Rhododendron infestation. Project partners include the

National Trust, Natural Resources Wales (previously the Countryside Council or Wales and

Forestry Commission Wales) and Gwynedd Council, as well as various volunteer groups.

Using local contractors, over 600ha of land has been treated to date (winter 2014), primarily

around the Nant Gwynant/Beddgelert area, the Ffestiniog Valley and along the Mawddach

Estuary. To put it into perspective,

that’s around the size of 560

standard football pitches!

Treatment involves three stages of

work – the primary phase of

clearance, and a secondary and

third phase to tackle re-growth.

These are usually undertaken 2

and 5 years after the initial work

respectively. Methods of control

are dependent on factors such as

accessibility, density and height,

but the most common are cutting

and then burning or chipping the

vegetation, stem injecting

individual plants with glyphosate

based chemicals or simply

spraying the leaves of the plant

using standard knapsack

equipment (usually used for

treating re-growth during the

second and third phase of work).

Further monitoring is undertaken

post treatment, usually five to 10

years after the third phase of work

is completed, to ensure re-

colonisation has not taken place.

What you can do

Almost all the Rhododendron which we now see growing in the natural environment originated

from gardens, where it is often planted as an ornamental plant, particularly since the post

Victorian era. Whilst the popularity of Rhododendron ponticum as an ornamental plant has

somewhat lessened in recent times, those plants which remain, unfortunately, still provide a

significant seed source into the wider environment. Consequently, if you have Rhododendron

bushes growing in your gardens, then we ask that you destroy those plants and replace them

with more appropriate species of tree or shrubs. Staff from the Conservation and Agriculture

department at Snowdonia National Park can provide free advice regarding suitable

management techniques and/or appropriate species for re-planting including other species or

hybrids of Rhododendron should it be required.

With continual support from relevant stakeholders, efforts to control the spread of

Rhododendron will persist, both complementing work already undertaken, and expanding into

areas that have so far been untreated. It is hoped that with adequate resources, continued

efforts and strategic implementation of work programmes, Snowdonia National Park can once

again be free of Rhododendron ponticum.

Conclusion

Rhododendron ponticum is a highly invasive non-native species that has had dramatic adverse

impacts on some of Snowdonia’s natural habitats. Its ability to out-compete natural vegetation

and dominate vast areas of the landscape alters the functioning of natural ecosystems and

degrades the quality of services they provide. Whilst it is acknowledged that further research

needs to be undertaken to measure the true extent of its impact on elements of the

environment, they are considered negative amongst experts in the field. With sustained

management and effective partnership working, successful eradication of Rhododendron

ponticum is possible, allowing for the recovery of affected habitats and associated services.

However, this will only be possible with both long-term and landscape scale management, and

with the support of sustainable funding streams.

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15. Snowdonia National Park Authority, Penrhyndeudraeth.

UK National Ecosystems Assessment (2011). UK National Ecosystems Assessment Technical

Report. UNEP - WCMC, Cambridge.

Welsh Government (2013) The Action Plan for Pollinators in Wales. Welsh Government, Cardiff.

Annex I

Service Group Ecosystem Service

Mountains, Moorlands

Woodlands Semi-natural or Freshwater habitats

and Heath

unimproved grassland

(lakes and rivers)

Crops

Livestock

Wild fish

Provisioning Timber

Water

Peat

Genetic resources

Cultural Asthetic value

Climate

Hazard (flood and

erosion)

Disease and pests

Regulating Pollination

Water quality

Soil quality

Air quality

Soil formation

Biodiversity

Supporting Nutrient cycling

Water cycling

Primary production

Very High

High

Moderate

Low

N/A