Cultivation of Khaya for timber

President Maithripala Sirisena addressing the 50th anniversary of State Timber Corporation has said: “It is necessary to increase the importation of timber to meet the country’s needs in order to aid increase forest density while protecting the forest resources.” This was reported by Daily FT on 5 April. Apparently the Department of Forest Conservation has failed to educate the President of khaya trees, currently being cultivated by the Department.

Khaya tree

Khaya is a fast growing tree, yielding high quality timber, growing to a height of 80-100 feet, reaching three to five feet in diameter and the trees could be harvested in mere 10 to 12 years. The yielding timber is similar to mahogany, whereas mahogany requires 20 to 25 years to mature. Young khaya plants develop an early deep root system, making it drought resistant and can be successfully cultivated throughout the low elevation regions of the country, thriving in wet as well as dry regions, even in poor soils. Physically, the tree has a large foliage, does not drop leaves periodically, the bark is dark grey to grey-brown in colour and the trunk without buttresses.

Khaya, also referred to as “African Mahogany,” a tree similar to mahogany, is natural to West Africa and Madagascar. Khaya timber has been exported from West Africa (Gambia) to Europe since the first half of the 19th century. In Africa, with high demand from Europe, harvesting of natural Khaya has been so heavy, leading to threat of extinction. Khaya is considered a vulnerable species has been included into the ‘IUCN (International Union for Conservation of Nature) Red List of Threatened Species’.

Introduction to Sri Lanka

The tree was introduced to Sri Lanka in the 1960s by the Forest Department and with young plants produced from imported seeds were available to public for several decades. But the public was unaware of the value of Khaya and the unsold young plants were planted by the roadside. 

Khaya is a genus of seven species of trees in the mahogany family and the locally introduced variety is Khaya Senengalensis. Mature khaya trees can be seen along most roads around Kurunegala, on Kandy Road near Kegalle, also near Batticaloa town. Even to date, the Department has failed to inform the value of timber with the possible cultivators and prospective end users.

I planted 10 khaya plants in my garden in 2002 received from the Forest Commissioner. He informed that the seeds were imported and cost the Department Rs. 135 per plant, but were sold to public at Rs. 3.50. I managed to get few more plants from the Forest Department sales centres. Four years ago I harvested the trees, got them sawed, treated and kiln-dried and used the timber in my living room floor, also in kitchen and pantry cupboards. My using khaya timber as flooring material was solely based on the information on the internet that khaya had been used in Europe as flooring for centuries.

Based on my experience I wrote two previous articles that appeared in Daily FT – ‘Khaya: The wonder tree for commercial cultivation’ can be viewed at http://www.ft.lk/2014/08/14/khaya-the-wonder. I discussed the growing and uses of Khaya timber in my second article ‘Khaya, flooring for export market,’ which appeared on 17 February 2016 and is available at http://www.ft.lk/article/525703/Khaya–flooring-for-export-market.

Propagation

Similar to mahogany, khaya is expected to produce flowers and seeds for propagation. Forest Department had been importing seeds for their plants. I had over 15 khaya trees, some over 12 years of age, but did not come across any fruits. On researching over the internet, I learnt khaya trees flower only when they are mature and over 25 years old. Also, flowers do not accept pollen from the same tree for pollination, thus needing multiple trees at the same location. 

Khaya timber

When harvested khaya wood is pale in colour compared to mahogany. But on drying and planing, grains surface and the timber becomes darker than mahogany. Khaya timber with interwoven grains is harder, heavier than mahogany, more difficult to cut and saw, sometimes tending to peel off during planing. Heavy fibre in khaya gives it a springing effect and is used in boat building. Khaya timber is resistant to borer and termite attacks and is used mostly in the manufacture of furniture, wardrobes, flooring, etc.  

The fast-growing khaya can easily overcome the shortage of timber for the manufacture of furniture, kitchen and pantry cupboards, flooring, as well as door and window frames and sashes. Also a word of caution: Khaya timber tends to warp and bend during drying, therefore needs to be kiln dried prior to usage. When I used khaya for the living-room floor in my house, I got the timber chemically treated and kiln-dried. Today after over two years, there are no visible gaps between planks, the joints could be noted only due to change of grain pattern from one plank to the other.  

Until recently mahogany and teak were the favoured varieties for replanting, maturing in around 30 years. Mahogany grows well in wet zone and moderately high rain-fall regions, whereas Teak is suited for drier climates as the dry-zone. Most local indigenous timber varieties are slow growing, would take well over 50 years to mature and yield timber. Thus if khaya be popularised would satisfy the timber requirement of the country. But the problem is getting young plants for cultivation. Currently, although some of the Forest Department’s plant nurseries have young khaya plants they are reluctant to sell to public, claiming the plants are meant for their own plantations and will only sell few plants to each customer.  

Considering the excellent timber quality, the short growing period and usability khaya has an enormous potential as a commercial cultivation and demands far more attention from the researchers as well as the business community. In addition if cultivated in bulk, veneers could be exported, but importers quality requirements are specific, therefore the cultivation of trees and production will require adherence to buyers’ specifications.  

Getting khaya plants for cultivation

After the publication of my previous articles, number of readers contacted me to get khaya plants, unfortunately I was unable to help them. However, during my travelling last year (2017 March) I came across the FD plant nursery at Habarana on Polonnaruwa Road which had a large khaya nursery and sold plants to customers, but a few plants each. Upon inquiry the staff informed that they received khaya seeds from their Ibbagamuwa nursery. 

A few days later travelling on Ibbagamuwa-Matale road I came across the FD’s Ibbagamuwa plant nursery, nearly five km from Ibbagamuwa town. They had a large nursery but plants were not for sale, as they were allocated to replant 25Ha of harvested teak plantations. But I learnt from the staff that the khaya seeds were collected locally.

Khaya seeds

During discussion with the FD officials it slipped out that the seeds were collected locally from a school garden around five km from the main road on a gravel by-road. The road concerned is a minor access road to villages on the canal bund carrying Batalegoda Tank waters to cultivators. They did not expect me to visit the location. I had noted the by-road earlier and decided to try the road. 

Travelling from Ibbagamuwa around four km towards Kurunegala is a small bridge over the canal carrying waters from Batalegoda Tank. The tank bund carries a small gravel road (a few weeks ago i.e. late March, I noted the road has been asphalted) and around five km away is a primary school accessed by a small concrete bridge over the canal, with the school play-ground abutting the canal. Around the small play-ground is a group of large khaya trees, around 25 in number, all mature, possibly over 30 years old.

I noted large number of young khaya plants on the canal edge, some cut down but re-growing on the canal bund. On entering the playground I found large numbers of khaya seeds under the trees. The playground has been swept of fallen seeds along with the leaves. I also noted there were hundreds of small khaya plants at the ground edge (larger ones have been cut away). I collected few hundred seeds on both occasions, from thousands of seeds lying on the ground. I explained to the children who were paying cricket on the grounds the value of seeds, but wonder how many realised the value of the seeds they were sweeping and burning away.  

My second visit in March was expecting to collect seeds as the previous year. But I noted the seeding season was nearly ending and the season possibly be January to April. For an interested person some seeds may still be available on the ground and hundreds of khaya plants suitable for replanting can be collected from school grounds with permission from the school principal, also at the canal edge.

Fruits from khaya trees

Established khaya trees begin to bear fruit when the trees are over 25 years old and fruits are globular and size of an orange. When fruits mature the hard fruit skin splits open up as petals allowing the flaky seeds to fly-away in the wind. The flaky seeds are around 30mm long, oval shaped, with 50-100 seeds packed inside each fruit. Dispersal of the seeds is by the wind. The maximum dispersal distance is over 50 metres, but about 75% of all seeds are deposited within 30 metres of the parent tree.

As the trees bear fruit only after maturity taking 25 years, harvesting of younger trees for timber will prevent the natural propagation of the species. Also natural dying age of the tree or the cessation of flowering is unknown. Thus maximum usage should be made from the current production of seeds from the trees.

Planting seeds

Of the seeds collected, after couple of days, I planted 22 seeds into black polythene containers filled with compost and kept in the shade. The seeds were immersed in water for 24 hours prior to planting and were watered morning and evening. On the ninth day few sprouts were visible and by the 12th day 20 seeds have germinated, giving a germination percentage of over 90%. Last year too I got a similar germination rate, but when the seeds were planted four months after collection, none germinated, indicating need to plant seeds early after collection.

When seedlings are grown in small containers they can be replanted when they reach over 30cm height and having fully developed compound leaves.

Growth

Khaya is a fast-growing plant, during the first year, the seedling develops a strong, deep taproot and the established plants are drought resistant. In my garden off Piliyandala, the khaya plants collected from the Forest Department in March last year were planted in May. Today, after 11 months, plants have grown to over 12 feet high (see picture), possibly due to my having planted them with compost, also plants attempting to overtake the adjoining tall wall. Matured khaya plants are resistant to flooding, hence the tree can be considered for planting on lands that undergo periodic flooding. But the tree develops a network of surface roots that can cause damage to nearby buildings.

Khaya grows in poor soils and could make good use of vast acres of abandoned lands in the dry zone, former forests, burned down, cultivated and discarded by the chena cultivators.  The tropical plant can be grown up to elevations of 1,000 metres. The rubber plantations abandoned due to labour shortages could be replaced with khaya. Rubber tapping commences after five years and good yields only after seven years; khaya could be harvested in a mere 12 years and will only need occasional labour for pruning. The short growing/maturing period would certainly interest investor growers.

Researching over the internet I found some interesting facts on growth in African countries. (a) In Ghana, the average height of seedling trees after 30 months was 2.5 metres and the average stem diameter 4-4.5cm. (b) In Malawi, planted trees reached a height of eight meters and a diameter of 9cm after seven years. (c) In Côte d’Ivoire, young trees planted in the open in the semi-deciduous forest zone reached an average height of 12 meters and an average bole diameter of 18cm after 10 years. However, trees planted in the evergreen forest zone were only 6 meters tall and 9cm in diameter after eight years.

The poor growth in African countries may be due to their short rainy period of only 4 months followed by 8 months of absolutely no rain (Hammattan period). But in Sri Lanka well distributed rain-fall speeds the growth, also results higher moisture content in harvested timber, necessitating kiln drying.

Khaya as an elephant barrier

In Sub-Saharan countries in Africa, khaya tree do not shed leaves during the dry-season and cattle feed on khaya leaves. In my garden Black Monkeys are regular visitors, but I have not seen them consuming khaya leaves. It should be possible to plant khaya along the electric fences put up as elephant barriers. Here, instead of a single row at least three rows of trees would be necessary, to create a physical barrier and discourage elephants.  

Future supply of seeds

Currently, the Forest Department gets its khaya seeds from the Primary School Grounds near Ibbagamuwa (maybe other locations as well). But for how long? With khaya producing fruits only after maturing for 25 years and with trees being harvested for timber in 12 years, it does not leave many trees until fruiting. 

Trees planted by the roadside especially in Kurunegala region may be bearing fruit, but collecting seeds are impractical. There may be other locations (some may not be sufficiently mature today, but could yield in a few years), need to be investigated and noted. I have noted a row of well grown khaya trees in the Katunayake airport grounds, possibly 15 years old.

President Sirisena, who emphasised the importance of increasing the forest density, proposed importing timber to save local forests needs to be educated on khaya. The President who visits countrywide regularly could visit the Primary School in Ibbagomuwa and inspect the khaya trees around the school playground. 

The President could declare the khaya trees around the school grounds as a national treasure, to save the trees from possible destruction and also instruct the Principal, teachers and the students to collect all seeds, produce seedlings, all could be sold to Forest Department and the public, generating an income to the school. If all seeds are collected, the school could help to produce nearly a million plants a year, supporting the President’s initiative to increase forest density and the import timber could be suspended in a decade and export of khaya veneers could earn valuable foreign exchange.

In addition, the President could instruct five school-ground peripherals in every electorate (that are suitable for khaya cultivation) be planted with khaya. Growing trees would give shade to the students and in 25 years will supply ample seeds for the future generation. Most importantly, public would be made aware of khaya and its uses.