INVADERS IN KNUCKLES MOUNTAIN RANGE

Pictures and text by

Dr. Lalith Gunasekera

Invasive Plants Specialist, Melbourne, Australia

The Knuckles mountain range could be considered part of Sri Lanka’s heritage. The importance of the knuckles mountain range is due to several factors such as mountain peaks, crystal clear water, cloud forests and exquisite flora and fauna. The remarkable feature of this area is that most of the climatic conditions of Sri Lanka can be found within the extent of a mountain range.

All these climatic conditions can be experienced within half an hour walks through this valley. In the Knuckle mountain range a total of 1,033 flowering plants belonging to 141 families have recorded. Among them 255 are tree species while the balance consists of shrubs and herbs. Considering all these factors, UNESCO included this area under World Heritage List on 30th of July 2010.

There are two major roads to this mountain range. One is through Matale-Rattota and Riverston. The other is via Hunnasgiriya-Meemurray road. I travelled on both roads in August this year and found several emerging invasive plants within the protected areas of this wonderful place. Some of the species are at their early stages of invasion. Thus, it would be easy to manage them before they get established and invade those important areas and cost massive amount of money and effort to manage them in future.

popcorn csassia

Botanical name: Senna

didymobtrya

This cassia species is being spread in knuckle mountain range especially between Hunnasgiriya - Meemuray roadside and forest areas. The plant originated in Central Africa. It is usually a several stemmed shrub or tree about 9 m tall. It is a hairy, aromatic shrub usually growing up to about five metres tall but known to reach nine metres at times. Its leaves are up to half a metre long and are made up of many pairs of elongated oval leaflets each up to 6.5 cm long. The plant has a strong scent which has been variously described as being reminiscent of mice, wet dog, peanut butter. The plant flowers plentifully in racemes bright yellow flowers, with some flowers also occurring in leaf axils. The flower raceme has open flowers on the lower part with unopened buds at the tip covered in stark brownish green or black bracts. The flower has five concave petals each 1.5 to nearly 3 centimetres long. The flower has ten stamens, usually seven fertile ones and three sterile staminodes. Some of the stamens have large anthers measuring a centimetre long. The fruit is a flat brown legume pod up to 12 centimetres long which contains up to 16 beanlike seeds up to a centimetre long each.

Suddha

Botanical name: Austroeupatorium

inulifolium

This is the biggest invader in Knuckles mountain range. Austroeupatorium (Suddha) plant is similar appearance to siam weed (Chromolaena odorata) and belongs to the same plant family but grows at higher elevations. It is a neotropical plant widely distributed in its native South America from Panama to Argentina. This plant was introduced to Sri Lanka as a flowering plant as well as green manure. This is very aggressive invader spreading along the Knuckle mountain range especially in Riverston area as well as through Hunnasgiriya to Meemuray road. Suddha plant is a perennial spreading shrub grows up to 2.5 m tall. Stems covered with short hairs and moderately branched. Leaves are simple and opposite. The plant produces creamy white flowers.

Crofton weed, Mexican devil

Botanical name: Ageratina

adenophora

Crofton weed spreads rapidly and has become a nuisance in many areas of Sri Lanka. A member of Asteraceae family, crofton is a native of Mexico. It is present as a weed in india, Canary Island, Jamica, Hawaii, Fiji, New Zealand, Australia and USA.

Crofton weed is a shrubby perennial with a woody rootstock and numerous upright branching stems. It usually grows 1-2 m high. Young stems are soft and leaves are bright green trowel shaped, 50-75 mm long, 25 -50 mm wide with the toothed margin.

Flowers are white, in small, dense heads at the ends of the branches. Seeds are slender, angular, 2 mm long, almost black with fine white hairs at the tip. I observed this plant species at the Knuckles mountain range near Riverston.

Mist Flower

Botanical name:

Ageratina riparia

This is the second biggest invader in the Knuckles mountain range. Mist flower plant was introduced to Sri Lanka as an ornamental plant. Mist flower is a low growing, sprawling perennial plant 40-60 cm high. It has numerous branching stems which produce roots at the joints when they touch the ground. Leaves are opposite, mostly 7.5 cm long and 2.5 cm wide, toothed along the edges and tapered at each end.

White flowers, similar to crofton weed are produced. The plant prefers a damp, shady environment and in these areas it can impede the growth of native ground cover species and prevent the establishment of many native seedlings. If uncontrolled this aggressive plant can completely dominate native vegetation and modify the composition of native forest and stream side environment.

Mist flower plant has seen in growing along the trail of Horton Plains as well as World's end. I have clearly seen it along the trail. Further it was heavily infested in knuckles mountains specially along the road to Telecom Tower road in Riverston.

Wild tobacco tree

Botanical name: Solanum

mauritianum

The highly invasive environmental weed originated in Argentina. Wild tobacco plant has spread in South Africa, Uganda, USA, Australia, Polynesia and New Zealand.

Plant has oval shaped leaves, upper surface green and sparsely hairy, lower surface grey or fawn, densely hairy. Sharply pointed tips. Flowers numerous in flat topped clusters to about 15 cm diameter at tips of branches. Flower has five petals with violet colour. Fruits are berries, round, green turning dull yellow. Large number of seeds are produced by the plant. Seeds are spread by water, birds, humans and vehicles,

I have noticed that the plant has been spreading along the road to Knuckles via Riverston and Bambaralla area.

Wild tobacco plant can tolerate shade and moderate drought once established. It can invade grassy woodlands, damp and wet forest, gullies and other moist sites in both disturbed and intact native vegetation, rain forest edges, roadsides and pastures.

Yoda Nidikumba

Botanical name: Mimosa pigra

I never expected the next invader in this area. Unfortunately, it was Giant Mimosa (Yoda Nidikumba). This plant started its journey from the Mahaweli Ganga bank and reached the entrance to this mountain range. I have seen several bushes in Panwila and Bambaralla area. It is high time they were removed from this area before it gets established ruining this beautiful environment. These plants have round pink flowers and plenty of thrones along the stems.

Time has come to protect the Knuckles range from these alien plant invasions. Field botanists from relevant authorities should deal with these new and emerging plant species before they get out of hand.

Via Island
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Bhikkhu Nyanatusita - I believe that these micro dams are relatively a much lesser problem than the problem of invasive exotic plant species overtaking Sri Lankan national parks and forest reserves. My recent visits to Knuckles Range, Wilderness Peak NP, Bundala NP, etc. and the ecological destruction caused there by plant species such as Mist Flower, Koster's Curse, Purple Plague / Miconia, Clusia, African Elephant Grass (Gini Mana) and Prickly Pear confirm my idea that this problem is actually the number one threat to Sri Lankan nature and that a mass extinction of many Sri Lankan plant species and the insects and animals that live on them is increasingly taking place with only a few people being aware of it. 

In the eastern side of Knuckles one still finds road sides and village habitats with mainly native herbaceous plants, but in most other areas these important habitats have been completely overtaken by Gini Mana and other invasive weeds.

I noticed that people are planting Miconia in gardens, thus aiding the spread of this extremely invasive species. On the problems with this plant in Tahiti, see http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/inv_spp_summ/Miconia_calvescens.html    and  http://www.oahuisc.org/miconia/.

Many Sri Lankan fish species are also threatened due to introduced exotic invasive South American fish species such as the Knife Fish. Last year when I visited Kandalama, the fishermen were mainly catching the inedible Armoured Catfish, from Brazil, that was introduced through the aquarium trade. 


Cont....

The solution I think is best is that legislation is made that obliges land owners to remove classified invasive species and that a special government department is set up to deal with invasive species and with the power to find and remove them. Other countries such as the USA, Australia have such legislation and government departments. Since most of the country has been cleared of its native vegetation and is kept free from weeds by humans, it should not be impossible to maintain and keep the remaining natural parts weed free. 

The only specialist on Sri Lankan invasive plant species lives in Australia. His name is Dr Lalith Gunasekera. He has written several news paper articles and a book (published by Sarasavi) on invasive plant species, e.g. on those invading the Knuckles World Heritage Site, but as far as I can see his warning and recommendations have fallen on deaf men's ears.

His article on invasives in Knuckles is here: http://www.island.lk/index.php?page_cat=article-details&page=article-details&code_title=37339
It was written five years ago, and the situation is deteriorating rapidly. As I wrote last year, there is also a large infestation of the Peru Palm tree (Myroxylon) in the valley above Rambukuluwa, and Pinus trees are also spreading in grass lands.
Other articles by him are here: 
On invasives in SL in general: http://www.sundaytimes.lk/111002/Plus/plus_13.html
On invasives in Horton Plains: http://archives.dailynews.lk/2011/10/08/fea03.asp
On Suddha in Knuckles: http://www.srilankaguardian.org/2010/12/suddha-is-silence-destroyer-of-knuckles.html