Eco Advocacy

Threats to Biodiversity

There are a number of threats to Biodiversity. These may be summarised as: -

Introduction and spread of Disease's / pathogens
Invasive Species
Habitat Loss
Pollution
Population Growth
Over Consumption/ unsustainable Use
Climate Change

Introduction and spread of Disease's / pathogens

Ash Die-back

Hymenoscyphus fraxineus (formal known as Chalara) dieback of ash is a serious disease of ash trees caused by a fungus called Chalara fraxinea (C. fraxinea). Its sexual stage is, Hymenoscyphus pseudoalbidus (H. pseudoalbidus). Infected specimens are affected by leaf loss and crown dieback in invariably results in the death of the tree. This disease threatens the survival of the species.

The Daily Telegraph reported on the 10th November 2012 "The disease, known as Chalara fraxinea, which originated in Japan, is thought to have come over from Europe on the wind. There is no cure for ash dieback, which also spread into nurseries via imports."

The UK Forestry Commission reports that "In February 2012 it was found in a consignment of infected trees sent from a nursery in the Netherlands to a nursery in Buckinghamshire, England. Since then it has been found in a number and variety of locations in Great Britain, including a car park, newly planted woodland and a college campus. All these sites had received stocks of young ash plants from nurseries within the past five years."..."In October 2012, Fera scientists confirmed a small number of cases in East Anglia in ash trees at sites in the wider natural environment, including established woodland, which do not appear to have any association with recently supplied nursery stock. Further similar finds were confirmed in Kent, Essex and other counties in early November 2012."…"Hundreds of staff from government agencies have been out checking ash trees across the UK for signs of the disease during early November. It’s one of several actions to emerge from a meeting of the Government’s emergency committee, COBR, which Environment Secretary Owen Paterson chaired on Friay 2 November" It is estimated that there are upwards of 80 million ash trees in Britain and it follows that a spread of this disease could have devastating consequences. Ash trees provide a unique habitat for a wide variety of plants and animals.

Visit: https://agriculture.gov.ie/forestservice/treediseases/ashdiebackchalara/

Visit: http://www.forestry.gov.uk/chalara

Visit: https://www.rhs.org.uk/about-the-rhs/pdfs/publications/the-garden/2013/January-2013/Ash-dieback-latest-RHS-advice

In November 2012, the Irish Authorities reacted by introducing emergency legislation, which provides that: -

A person shall not land wood of genus Fraxinus L. into the State originating in countries where Chalara fraxinea is known to occur unless the wood –?

(a) is accompanied by a plant passport or an official statement stating that it originates in an area known to be free from Chalara fraxinea, or?

(b) is squared so as to remove entirely the rounded surface, or

(d) if sawn, with or without residual bark attached, has undergone kiln-drying to below 20 % moisture content, expressed as a percentage of dry matter, achieved through an appropriate time and temperature schedule. There shall be evidence thereof by a mark ‘Kiln-dried’ or ‘KD’ or another internationally recognised mark, put on the wood or on any wrapping in accordance with current usage.

1. Further to the introduction of measures restricting the import of ash plants from areas within the EU that are known to have the disease, the movement of ash plants within the country are now also subject to plant passport requirements. Any nursery wishing to trade in such plants whether domestically or for export should immediately contact the Department.

http://www.merrionstreet.ie/index.php/2012/11/mcentee-announces-enhanced-ash-wood-ban/

Larch Disease

Phytophthora ramorum (P. ramorum) is a fungus-like pathogen that kills many of the trees that it infects. It was found on Japanese larch trees in South West England in 2011, and the outbreak in woodlands in the Afan Valley, near Port Talbot, Garw Valley, near Bridgend, and the Vale of Glamorgan is the first time it has been encountered on larch elsewhere in Great Britain.

The UK Forestry Commission reports that experts In Wales are working to contain an outbreak of Phytophthora ramorum (P. ramorum) infection in Japanese larch trees in South Wales. “Extensive felling of affected larch trees in South Wales is about to begin and Forestry Commission Wales is working with timber processors and others to ensure biosecurity measures are put in place to allow logs from the infected trees to be taken to mills for conversion into timber”

The commission further stated as follows on its website: -

Phytophthora ramorum (P. ramorum) is a ‘quarantine’ organism under European Union law and its presence on trees or woodland plants must be notified to the relevant authorities (Forestry Commission, Fera, Welsh Assembly Goverment, Scottish Government). It was first found in Britain on a viburnum plant in a nursery in 2002.

• P. ramorum causes the disease known as "sudden oak death" in the USA, where it has killed millions of American native oak and tanoak trees. However, its American nickname is a misnomer in Britain, where laboratory tests have shown that our two native species of oak, sessile and pedunculate oak, are much more resistant to P. ramorum than their American cousins. Fewer than five native oak trees have been confirmed with P. ramorum infection in Britain.

• It should not be confused with acute oak decline (AOD), which is a separate disease affecting oak trees in the Midlands and parts of Wales and South East England, and in which a newly discovered bacterium species appears to be involved.

• P. ramorum kills most trees that it infects, but symptoms vary according to the type of tree or shrub. On Japanese larch (Larix kaempferi) trees, it causes shoot tips to wilt and needles to turn black and fall prematurely. Numerous cankers that bleed resin can appear on branches and the upper trunk. Infected Japanese larch trees produce particularly high numbers of the spores that spread the disease – five times the level produced on rhododendron - meaning the disease can quickly affect a large number of trees and shrubs.

• P. ramorum has not been found infecting any European larch (Larix decidua) or hybrid larch (Larix x eurolepsis) trees, which are the other two species of larch grown in Britain, but these species are being kept under close surveillance.

• P. ramorum can be spread on footwear, vehicle wheels, tools and machinery that have been used in infected forests, or by the movement of infected plants. It can also be spread in rain, mists and air currents, and scientists at Forest Research, the Forestry Commission’s scientific research arm, believe this is the likely pathway for the Japanese larch infections from South West England to South Wales.

• In South West England, P. ramorum has affected a mix of Forestry Commission and privately owned forests.

• P. ramorum has not been found on any trees in Scotland.

• Complete figures are not available for Japanese larch numbers alone, but all three larch species together cover an estimated 134,000 hectares in Britain, or about 5 per cent of total woodland. Individual country figures are:

· Wales – 23,000ha / 8 per cent;

· England – 43,000ha / 4.3 per cent;

· Scotland – 65,000 ha / 5.1 per cent.

(To convert hectares to acres, multiply by 2.47)

Larch is a durable, versatile timber that tolerates changes between wet and dry conditions very well, and resists rotting when used in the ground. It is therefore in demand for outdoor uses such as fence posts, fence panels, exterior wall cladding, boats, sheds and furniture, as well as indoor uses such as flooring and chipboard. It is easily stained, worked and finished.

Source: UK Forestry Service

http://www.forestry.gov.uk/pramorum

Sudden Oak Death

Sudden Oak Death is a tree disease caused by the plant pathogen Phytophthora ramorum. The disease attacks oak species and has had devastating effects on forests in California and Oregon.

The UK forestry Commission comment on their website that: -

Symptoms of acute oak decline include dark fluid bleeding from splits in the bark on tree trunks, and as affected trees approach death there is a notable deterioration of the canopy, or tree tops, and ‘dieback’ of the branches. The condition can kill a tree in as little as four or five years, and it has been found affecting hundreds of trees across central and south-east England and parts of Wales.

• The oak is an iconic part the British countryside, and widely celebrated in our art, literature, culture and history. It is an important component of our natural environment, and produces some of the world’s finest timber.

• Acute oak decline should not be confused with “sudden oak death” (SOD). Sudden oak death is a term used in North America for a disease caused by a fungus-like pathogen called Phytophthora ramorum which has killed millions of North American native oak and tanoak trees in California and Oregon. Although it is also present in Great Britain, it has mostly affected shrub species and heathland plants, and small numbers of other tree species. Japanese larch trees in the West Country have also been infected with SOD. Britain’s two native oak species, pedunculate and sessile oak, have proved much less susceptible than their American cousins, with only a handful being infected.

The terms "decline" and "dieback" are used by foresters and arborists to describe conditions in which a number of damaging agents interact with one another to weaken trees and bring about their deterioration, and sometimes premature death. Decline and dieback can be either ‘chronic’ (slow and progressive) or 'acute' (rapid). Damaging agents associated with decline include insects, diseases and extreme weather. Healthy trees can usually withstand sporadic attacks by pests or diseases when they occur singly, but often suffer significant damage if they occur simultaneously or when the trees are stressed by other factors, such as drought or flooding. Decline can also set in when sustained attacks occur over a number of years in succession. In cases of acute decline the trees experience a rapid deterioration in health, sometimes dying within as few as four years of the onset of first symptoms. Chronic decline occurs over many years. Oak trees can often recover from chronic oak decline, particularly if there is a reduction in the factors that cause it.

Source: UK Forestry Service

http://www.forestry.gov.uk/newsrele.nsf/AllByUNID/54C6BFC2DDC5BEFF80257727003981E6

Dutch Elm Disease

Dutch Elm disease is caused by as many as three relates species of fungi from the genus ophiostoma which are disseminated by various elm bark beetles. The disease was identified in 1921. It is believed to have originated in Asia, but has wreaked destruction throughout Western Europe and northern America. The three species of fungi are:

ophiostoma ulmi which is thought to have reached Europe in 1910 and reached North America on imported timber by 1928.

ophiostoma himal-ulmi which is indemic to the Western Himalaya.

ophiostoma novo-ulmi which is highly virulent and which has devastated elms in both Europe and North America since the 1940's.

One could write a lengthy thesis on the issue and so the reader is referred to the following sites for further information: -

The UK Forrestry Service: http://www.forestry.gov.uk/fr/HCOU-4U4JCL

The US Forestry Service: http://na.fs.fed.us/fhp/ded/

Wiki: http://en.wikipedia.org/wiki/Dutch_elm_disease

Tree Council of Ireland: http://www.treecouncil.ie/irishtrees/wychelm.html

Bleeding Canker of Horse Chestnut

Bleeding Canker of Horse Chestnut is a fungal pathogen known as Phytophthora (Brasier and Strouts,1976). This disease was first reported in the 1970’s. This was an uncommon disease until around 2008, when incidences of the disease have become much more prevalent on the common horse chestnut (Aesculus hippocastanum). The diseased may be recognised by the presence of extensive bleeding areas on their stems and sometimes on their branches. Trees of all ages are affected with young trees being particularly vulnerable.

See The Forestry Service:

http://www.forestry.gov.uk/fr/INFD-6KYBGV

Juniper Blight

Phytophtora austrocedrae is a pathogen associated with die-back of the juniper species. The pathogen attacks the roots and stem bases of juniper. This was identified on Juniper plants in Cumbria in 2012. It was also found to infect Lawson cypress and Nootka cypress trees in Scotland.

This should be distinguished from the more common 'Juniper Tip Blight' which is caused by the fungus Phompsis juniperovora which has been in the British Isles for many years.

See The Forestry Service: -

http://www.forestry.gov.uk/website/forestry.nsf/byunique/infd-8rajz3

http://www.forestry.gov.uk/pdf/phytophthora_austrocedrae_juniper_factsheet.pdf/$FILE/phytophthora_austrocedrae_juniper_factsheet.pdf

http://plantclinic.cornell.edu/factsheets/junipertipblight.pdf

Box Blight

Is a disease caused by 2 fungi: Cylindrocladium buxicola and Volutella buxi. They are often found together. The fungi cause the leaves to turn brown and fall from the plant. Plants become scrawny and emaciated. Spores are difficult to see with the naked eye, but it may be possible to see spores on the underside of the leaves in wet conditions. They may appear white for Cylindrocladium buxicola and pink for Volutella buxi.

It is very difficult to kill this disease. Should one acquire new plants, best practice is to quarantine in an isolated area for a period of time to ensure no fungi develops on the plants. Buxus is a heavy feeder and hungry plants will be far more susceptible to infection. Therefor it is recommended that plants / hedges be fed with fertilizer low in Nitrogen and high in Potassium; e.g.; 0-10-20. It is also advisable to trim plants/hedges less frequently to avoid leaving plants open to infection. Collecting old plant derbies will also help as it is speculated that the fungi can survive for up to 5 years on diseased leaves.

Fire Blight

Is caused by the bacterium Erwinia amylovora. It is a disease affecting species of the Rosacea family wich includes Malus (Apple's), Pyrus (Pears), Cotoneaster, Photinia, Pyracanta, Sorbus (Mountain Ash), Amelanchier, etc.

Given the wide variety of species affected, this is a significant disease.

See the following pages: -

http://www.fera.defra.gov.uk/plants/publications/documents/factsheets/fireblight.pdf

http://en.wikipedia.org/wiki/Fire_blight

Asian Long Horn Beatle

Beatle larvae chew through to the middle of the tree. This is a deadly invasive species which should perhaps be included on the invasive's page, but given its connection with trees, it was decided to provide the information here.

See the following pages: -

http://www.forestry.gov.uk/forestry/HCOU-4U4J45

http://www.bbc.co.uk/news/uk-england-kent-18998671

2. Invasive Species

See separate page on this issue