Establishment of relationships of growth at 7-year old mahogany trees with selected site factors

Establishment of relationships of growth at 7-year old mahogany trees with selected site factors in low country wet zone, using GIS as a tool

Himesha Randeni and Upul Subasinghe

Paper presented for the 14th International Forestry and Environment Symposium 2009

Mahogany (Swietenia macrophylla) is an exotic tree, which is heavily adapted to the climatic conditions of wet and intermediate zones of Sri Lanka. Although the state sector manages mahogany with longer rotations, private sector expects to achieve the maximum timber yield within a shorter period. Due to the land scarcity, many of these mahogany plantations have been established in barren and rubber uprooted lands which were heavily degraded. Therefore the soil conditions and site factors directly affect the growth of the mahogany within short rotations.

The present study was carried out in a 7 years old mahogany monoculture plantation established in Gomaragala, in low country wet zone of Sri Lanka to find out the effect of soil and site factors to the mahogany tree growth. Extent of this forest is 20.7 ha and it is managed by a private plantation company. This forest has been divided into 2 lots for the purpose of administration and further divided into 240 plots of 20 perch each.

In order to identify the relationships, tree dbh and height were used as growth parameters. Slope, bedrock establishment and terrain were selected as selected site factors. The growth parameters (i.e.dbh and height) were measured for all the trees in plantation (one measurement from each plot). Slope and terrain as geographical parameters were measured of all 240 plots in the entire plantation.

Since the regression based methods were not adequate for both qualitative as well as quantitative parameter analysis, GIS based analysis was decided to use for the present study, using ArcView 3.3. In order to create digital maps, the survey plan of the selected forest was digitized and georeferanced using 10 ground control points collected by a GPS data receptor. Then the georeferanced base map was digitized to demarcate all the plots and other land marks. After that different maps were prepared in vector form separately for each parameter. However, for the analysis, all these vector layers were converted to raster layers. Raster layers were then reclassified and overlaid two or three layers at a time with the growth parameters to identify the effects. Then map analysis was completed to make decisions regarding tree growth in different site factors.

Results revealed that there are significant relationships between tree growth and the selected site parameters. However, the best conditions for the mahogany tree growth in the particular area are the slope between 11⁰-24⁰, and shallow bedrock prevalence and stony terrain.

Change of crown diameter with dbh of mahogany

Change of crown diameter with dbh of Swietenia macrophylla (mahogany)

even-aged monocultures

Shanika Lakmali and Upul Subasinghe

Paper presented for the 14th International Forestry and Environment Symposium 2009

Mahogany is one of the renowned timber species for its beautifully grained, hard and red-brown wood. It is an introduced timber species, dominated in Sri Lankan forest plantations with fast growth rates and higher timber value. Mahogany plantations are widely established in the intermediate zone and low country wet zone in Sri Lanka. Recently, private sector has started to establish of mahogany monocultures with shorter rotations to gain high income.

Due to the lack of research studies on mahogany, the objective of the present study was to establish an empirical model to predict crown diameter accurately using dbh. For this purpose, data were collected from 16 mahogany monocultures in Kalutara, Ratnapura and Matale districts. In order to represent the whole plantation, sixty trees were selected from good, moderate and poor areas from each plantation.

In order to build a reliable model, theoretical basic structures were developed assuming the crown diameter is a function of tree dbh. This basic structure was fitted to the data as linear, exponential, and logistic form separately for different growth types. In addition to the untransformed variables, transformations were also made whenever possible. Suitable candidate models were preliminary selected by R2 and residual distributions. After further analysis, it was proven that the best results were given by the logistic model structure for good, moderate and poor site types (R2 = 92.0%, 71.4%, 65.9% respectively). In order to eliminate the difficulty of using separate models for different growth types, the possibility of using a common model for all growth types were tested. For this reason, one way ANOVA was used for residuals of different growth types generated after fitting respective models. Results indicated that it was possible to use a common model and therefore the logistic form was re-fitted to pooled data.

The final model was “crown diameter = 0.645 + 2.682 / (1+exp (-0.356 (dbh –7.749)))” and it had a R2 of 60.9%.

Establishment of relationships of growth with site factors and some selected soil parameters of a selected 7 years old mahogany plantation in Eheliyag

Establishment of relationships of growth with site factors and some selected soil parameters of a selected 7 years old mahogany plantation in Eheliyagoda DS, using GIS as a tool

B.Sc. Dissertation

Himesha Randeni and Upul Subasinghe

Mahogany (Swietenia macrophylla) is an exotic tree, which is heavily adapted to the climatic conditions of wet and intermediate zones of Sri Lanka. Although the state sector manages mahogany with longer rotations, private sector expects to achieve the maximum timber yield within a shorter period. Due to the land scarcity, many of these mahogany plantations have been established in barren and rubber uprooted lands which were heavily degraded. Therefore the soil conditions and site factors directly affect the growth of the mahogany within short rotations.

The present study was carried out in a 7 years old mahogany monoculture plantation established in Gomaragala, in low country wet zone of Sri Lanka to find out the effect of soil and site factors to the mahogany tree growth. Extent of this forest is 20.7 ha and it is managed by a private plantation company. This forest has been divided into 2 lots for the purpose of administration. However, for the sales purposes it has been divided into 240 plots.

In order to identify the relationships, tree dbh and tree height as growth parameters; slope and terrain were selected as geographical factors as well as soil texture, soil organic carbon level and soil pH levels were selected as soil parameters. The growth parameters (i.e.dbh and height) were measured of all the trees in plantation. Slope and terrain as geographical parameters were measured of all 240 plots in the entire plantation. Soil parameters namely soil pH, soil organic carbon and soil texture were measured for systematically selected 50 plots out of 240 plots to represent the entire plantation. There are some qualitative parameters namely tree growth, terrain, presence of bedrock, included into the present study. These were usually assessed to give a single value for each plot.

Since the regression based methods was not adequate for both qualitative as well as quantitative parameter analysis, GIS based analysis was decided to use for the present study, because it serves as an analytical and decision supporting tool. ArcView 3.3 was used for this purpose. In order to create digital maps, the survey plan of the selected forest was digitized and georeferanced by main 10 ground control points collected by a GPS data receptor. Then the georeferanced base map was digitized to demarcate all the plots and other land marks. After that different maps were prepared in vector form separately for each parameter. However, for the analysis, all these vector layers were converted to raster layers. Raster layers were then reclassified and overlaid two or three layers at a time with the growth parameters to identify the effects. Then map analysis was completed to make decisions regarding tree growth in different site factors and soil conditions with similar other environmental conditions. Since the soil pH, soil organic carbon level and soil texture were measured in selected 50 plots out of 240 plots, the raster layers were interpolated for entire area.

Results of the present study revealed that there are significant relationships between tree growth with the selected parameters. However, the best conditions for the mahogany tree growth in the particular area are the slope between 11⁰-24⁰, soil pH level bellow 4.0, soil organic carbon range between 9.0%-14.0%, soil with sand between 50%-70%, shallow bedrock prevalence and stony terrain.

Changes of branch and crown characteristics with stem parameters and age of Swietenia macrophylla even-aged monocultures

Changes of branch and crown characteristics with stem parameters and age of Swietenia macrophylla (mahogany) even-aged monocultures

B.Sc. Dissertation

Shyanika Lakmali and Upul Subasinghe

Growth predictions in the plantation forestry play a vital role in order to maximize the future gains specially in the field of economy. Plantations of mahogany monocultures in private sector directly focus in the timber production and thereby the financial gain. Tree growth is accompanied with the photosynthesis process and it increases the stem parameters of the trees. Therefore there is a close relationship between crown development and tree growth. In addition to that, crown growth causes a competition after the canopy closure in the forest plantations.

The main objective of the present study was to establish a series of empirical models for predicting the relationships between stem, crown and branch parameters. In addition to that an attempt was taken to predict the above parameters with age. It was expected to use those relationships to prepare a pruning schedule for mahogany monoculture plantations in Sri Lanka.

In order to achieve the objectives, data were collected from 16 mahogany monocultures in Kalutara, Ratnapura and Matale districts. In order to represent the whole plantation, due to growth differences, sixty trees were selected from each of plantation as twenty trees from each good, moderate, and poor growing areas. The measurements were taken including dbh, total tree height, crown diameter, height to the first branch, height to the second branch, branch lengths and base diameters up to two branches.

Regression analysis was employed to build the suitable relationships between related variables. Both linear and non-linear regression equations were tested for each relationship using MINITAB and GENSTAT statistical software. In order to obtain the best equations, both qualitative (R² ) and quantitative (residual distribution and fitted line plots) were used. Initially, the data were grouped as good, moderate and poor growth types. Then different theoretical model structures (linear with untransformed and transformed variables, exponential and logistic) were separately fitted to those data. After that the best model was selected for each relationship for each growth type. At this point, it was a must to select the similar model structure (with different regression parameter sets) for each relationship in each growth type.

According to the results, crown and branch variables were highly correlated with the stem variables such as dbh and total height. Therefore the predictions of the crown and branch growth could be expressed by using dbh and total height. It was not possible to build linear relationships and

In order to predict the required variable, 12 non-linear models were constructed. Then the possibility of using a common model for all growth types was tested for each variable with pooled data. However, only three models out of 12 models proved the possibility of using as common models for all growth types. The rest of models were therefore decided to use as growth specific ones.

Finally using those models, a pruning schedule was prepared for different growth types of mahogany monocultures in Sri Lanka.

Challenges faced by the private sector in establishing teak plantations in Sri Lanka

Challenges faced by the private sector in establishing eak plantations in Sri Lanka

Abstract of a seminar presentation

Prabhani Jayasekara

Teak was introduced to Sri Lanka in 17th century by Dutch. It was widely planted in dry and intermediate zones after 1950s. Teak has a long history of systematic management. The earliest Teak plantations in Sri Lanka are traced back to the late seventeenth century. Teak planting, which was once mainly the domain of government forest departments, is today attracting the interest of the private sector. The private sector has taken advantage of technical developments has succeeded in attracting private individuals to invest in teak.

Many private companies involve in Teak planting in Sri Lanka such as:

Forestree Investments limited - a subsidiary of Access Group of Companies

Sadaharitha Plantations Limited

HELP GRRN “Wanasarana” Teak Plantation Project

Green Vision Lanka Private Limited

In Sri Lanka first private sector large scale commercially managed teak plantation was started by Help Green (Pvt) Ltd in 1998 with a unit which is equivalent to a land extent of 41.6 perches with 100 teak trees.

The expected final harvest of the private forest plantations are much shorter than that of the Forest Department plantations and therefore very high financial inputs are necessary to uplift such plantation conditions.

Among the major challenges faced by the private sector in establishing teak plantations, land unavailability, social issues, environmental issues, lack of scientific information and research, management problems and unforeseen catastrophes (insects, pests, animal damages, weeds, and uncontrolled fires) become prominent. Quality of timber cut from private sector plantations will also be a major issue because timber cut from old teak trees which grow slowly in natural forests is more durable and harder and teak from young trees grown in plantations may be more prone to splitting and water damage.

The private sector Teak planters have successfully identified many of the above mentioned challenges and they have taken actions in order to avoid economic loss which can be caused due to those issues.

Challenges faced in establishing khaya plantations in Sri Lanka

Challenges faced by the Forest Department in establishing khaya plantations in Sri Lanka

Abstract of a seminar presentation

Benica Jayasekara

Khaya senegalensis is the scientific name for khaya, which belongs to the Family Meliaceae. It is commonly known as African mahogany or dry zone mahogany. It’s a fast growing tree species in dry conditions and grows up to 20-30m in height. Timber of khaya is hard, dense and reddish brown in colour.

Khaya is one of the major timber species used by the Forest Department in reforestation programs in dry and intermediate zones of Sri Lanka. It was introduced from Africa during 1960’s. However, most of the khaya plantations of Sri Lanka are less than 10 years old.

The reasons for the use of Khaya by the Forest Department is the high demand for timber, fast growth rates in dry and intermediate zones, tolerance to poor site quality and resistance to heavy weed competition, harsh conditions and diseases and pests (except borer). Moreover the rural community prefers khaya over teak because khaya is morphologically more similar to the native species in Sri Lanka. In addition to those, wild elephants do not damage khaya trees.

According to the Forest Department, khaya was selected as the best tree species for the dry zone. There are however, a few challenges faced by the Forest Department in establishment of khaya plantations. Expensive seeds, low seed viability, fertilization, weeding, multiple shoots, porcupine damage, black twig borer attack, red stem borer attack and the forest fires as examples.

Forest Department had taken remedial actions for these challenges and still they are doing further studies to improve the khaya plantations. Still the khaya plantations in Sri Lanka are less than 10 years and therefore the Forest Department might face more problems with the time, because the rotation age of khaya is 30 years and still the yield tables for this species has not been prepared.

Status and possibilities on forest certification in Sri Lanka

Status and possibilities on forest certification in Sri Lanka

Abstract of a seminar presentation

Manuri Gamage

Forest certification found its roots in the concern over rapid tropical deforestation in the 1980s and the 1990s. It is a process which results in a written certification being issued by an independent third party, attesting to the location and management status of a forest which is producing timber. Forest certification also provides consumers with a credible guarantee that the product comes from environmentally responsible, socially beneficial, and economically viable sustainably managed forests.

Sri Lanka has adopted only FSC certification by an independent, non-profit organization, formed in an effort to establish a global system for certifying that products come from well-managed forests. Only three multinational certification bodies accredited by FSC are currently issuing certification in Sri Lanka.

At present, certification is confined mainly to the rubber plantation sector in Sri Lanka. Only four such companies currently hold FSC forest management certification, out of large-scale plantation companies in Sri Lanka. Forty-two percent of the country's plantations are owned by small holders. Therefore, this group plays a key role in the rubber industry as well as in supplying raw materials to wood-based industries. None of the small-scale rubber plantations in Sri Lanka are certified. Out of the many manufactures only nine companies have obtain the chain of custody certification.

Facilitating group certification for small rubber plantation owners to obtain forest certification, encouraging certified plantation owners to focus on high-end species such as teak and mahogany where there is great potential to capture price premiums, building awareness among plantation owners of advantages of obtaining the certification other than price premiums, seeking new export markets for the certified timber and timber products, obtain approval for the FSC National standards and implement within the country, encouraging local organisations to obtain accreditation from FSC as a certification body, developing an internal certification scheme with its own standards can be mentioned as some of the potentials in forest certification in the country.

Why indigenous species were not popular in Sri Lanka?

Why indigenous species were not popular in Sri Lanka in plantation establishment?

Abstract of a seminar presentation

Piyumi Nanayakkara

Forestry has two main functions to fulfill which are recognised as protection and production. Due to significant reduction in the natural forest cover in Sri Lanka during the recent past through the agricultural development, shifting cultivation and settlements; the functions that can carry out by natural forests were reduced. That means natural forests were unable to provide these two functions at required level. Therefore forest plantation establishment was started in Sri Lanka.

Utilisable timber plantations in Sri Lanka mainly consist of man-made forest plantations belonging to Forest Department (96,250 ha), companies under the Ministry of Plantation Industries (16,463 ha), private companies and rubber and coconut plantations. According to the data recorded in the past, it is clear that most of the tree species used for the plantation establishment were exotics such as Teak, Eucalyptus, Acacia, Pine and Mahogany.

Data on indigenous and exotic species were collected through the literature survey to select the most suitable species for plantation establishment, based on three selection criteria named as growth and management characteristics, end product characteristics and Usefulness of the species.

Results concluded that exotics are the most suitable and popular plantation species that recommended for Dry, Intermediate and Wet climatic zones in Sri Lanka. Monocultures of exotics cause certain shortcomings, however, the advantages outweigh the disadvantages. Therefore there is no secret of selecting or popular of exotics in plantation establishment compared to indigenous species in Sri Lanka.

There are some indigenous species suitable as plantation species such as Kohomba, Ebony (Diospyros ebenum), Jak (Artocarpus heterphyllus), Mara (Albizia sp), Halmilla (Berrya cordifolia), Hora (Diptercarpus zeylanicus), Kumbuk (Treminalia arjuna) and Lunumidella (Melia dubia), however, they were not popular for plantation establishment as exotics due to several poor characteristics such as relative low growth rate and having longer rotation length, very low volume compared to exotics, poor wood working qualities, unavailability of straight bole, lack of published information on Indigenous species and felling restrictions etc.

Challenges faced by the private sector in establishing mahogany plantations

Challenges faced by Private Sector in establishing mahogany plantations in Sri Lanka

Abstract of a seminar presentation

Madhushan Lankathillake

Mahogany is one of the important exotic timber species which is used for forest plantations in Sri Lanka. Mahogany was introduced to Sri Lanka in 1880 and it was used as plantation species in 1887. Later mahogany plantations were established in low land wet zone and low land intermediate zones. Private sector involvement in establishing large scale mahogany plantations started in late 90’s. When establishing mahogany plantations private sector had to face various types of challenges.

Finding a suitable land to establish plantations is one of the main such problems. In wet zone most of the fertile lands are used for agriculture crop cultivation. Therefore available lands are infertile or abandoned lands such as abandoned lands after planting rubber for a long time period. Additional effort must be needed to improve these infertile lands. Lands with steep slops, ridges or rocky lands also cause several problems. Damage to the seedlings caused by shoot borer attack is another major problem. Effective low cost methods of controlling shoot borer attack have not been found so far.

In order to provide shade, mahogany seedlings are planted under the canopy trees but when these trees are removed mahogany seedlings may get damaged. An EIA has to be done when removing naturalized canopy treesif the area is over 5 ha in extent. These canopy trees absorb fertilizer applied to mahogany seedlings and this will cause reduction of growth of mahogany trees. In the wet zone weed growth is very fast. Mahogany seedlings have to compete with the weed growth. Therefore during first few years of planting weeding must be done properly.

Available lands also do not have proper access so that transportation of seedlings and equipments aree difficult. Most of the plantations do not have nurseries with in their plantations. Therefore they have to buy seedlings from other nurseries and this is an additional cost for the companies and seedlings may also get damaged while transporting.

Moreover, scientific research has to be done to generate improved varieties which are resistant to shoot borer attack and tolerant to light. Low cost and effective methods of controlling shoot borer attack must be found out. A proper fertilizer regime for mahogany has not been developed yet. There is a lack of previous growth data and yield tables for mahogany within private sector. Sometimes people’s interest in investment in forest plantations will be changed in the future. Loss of trust on investment and economic crisis in the country as well as in the world will be barriers on investment in present situation. Reduction of investments will be a financial restriction in establishment of forest plantations.

In order to obtain an additional income, herbal plants and spices can be planted within the sites of mahogany at early stages. An proper system must be introduced to reduce the barriers and time consuming legal procedures which have to be done for canopy removal and final harvesting. Further, scientific research must be done with the involvement of the government departments and experts in the field. Appropriate procedures have to be found out to utilize carbon sequestration potential of plantations to gain an additional income. Programs and necessary background have to be created where an international investments in forest plantation sector is allowed.

Principles, criteria and indicators used in forest management

Principles, criteria and indicators used in management of tropical wet evergreen forests

Abstract of a seminar presentation

Isurie Dharmasoma

Principles, criteria and indicators are used to define, implement and monitor the forest management. Primary framework for managing forests in a sustainable fashion is provided by principles. It provides the justification for criteria and indicators.

A set or situation which should be met to comply with forest management activities is described by criteria. Criterion itself cannot be measured and therefore indicators are used to measure criteria. Indicator is a quantitative, qualitative or descriptive attribute that indicates the direction of change when periodically monitored or measured. Therefore criteria and indicators are used to monitor progress towards sustainable forest management.

Ongoing international initiatives of criteria and indicators are Helsinki process, ITTO criteria, Lapartique process etc. Principles, criteria and indicators included in these initiatives are different to each other because they are applied to different ecological regions. ITTO (International Tropical Timber Organisation) criteria are used for management of tropical forests. They have introduced 7 criteria and 66 indicators which can be applied in tropical forest management. These criteria and indicators are used by certification bodies, government officials, forest managers, scientists etc.

Under ITTO criteria, criterion 1 is enabling conditions for sustainable forest management. Criterion 2 is forest resource security. Criterion 3 is forest eco system health and condition. Flow of forest produce, biological diversity, soil and water are criterion 4, 5 and 6. An economic, social and cultural aspect is criterion seven.66 indicators are comes under these 7 criteria.

Criteria and indicators are to be easy to apply. However there are limitations also. Therefore the correct application of criteria and indicators contribute to the sustainable forest management.

Contribution of Sri Lankan forests to non-wood forest products

Contribution of Sri Lankan forests to non-wood forest products

Abstract of a seminar presentatation

Padmi Gunarathne

Non-Wood forest products (NWFPs) have an important role in the rural economy of Sri Lanka and they also provide benefits of considerable importance at the national level. They have a major impact on the social and economic conditions of village communities by providing a wide array of materials which enrich and diversify rural life. The knowledge, skills and social customs relating to NWFPs have been passed from one generation to the next and form part of traditional culture.

There are various categories of NWFPs available in Sri Lanka. The most important are rattan and bamboo, medicinal plants, the products of hunting, tapping, honey and grazing etc. Around 40% of the rural population in the Dry Zone is forest dependent and derives some benefits from NWFPs. The annual income from NWFPs per forest dependent household in some parts of Dry Zone of Sri Lanka is around Rs 15,000.

Kitul (Caryota urens) is the most significant NWFP in the Wet Zone and it contributes over 70% of the total income of the household engaged in this activity.

Lack of policy guidelines, a shrinking resource base and inadequate knowledge on cultivation, management, harvesting, processing and storage are identified as the major issues which hinder the development of the NWFPs sector. Major reforms in policy, legislation and management strategies, together with a coordinated effort in research on cultivation, utilization and product development, should be undertaken for sustainable development of the NWFPs sector in Sri Lanka.

Establishment of farmers' woodlots in Sri Lanka

Establishment of farmers' woodlots in Sri Lanka

Abstract of a seminar presentation

Asanka Wijewarnasuriya

Farmers’ Woodlots are an outcome of some donor funded social forestry projects such as Participatory Forestry Project (1993-1999) implemented by the Forest Department. There are about 15,500 ha of Farmers’ Woodlots have been established in 19 districts of Sri Lanka. The major species used for this purpose is teak (Tectona grandis). In addition to that, species such as Neem (Azadirachta indica), Eucalypts (Eucalyptus species) and Khaya (Khaya senegelensis) have also been used. There are monocultures and mixed-cultures such as Neem-Teak mix.

People belonged to lower income groups have been selected for this programme and they were given incentives for the establishment of Woodlots. They were given lands under a lease agreement for a period of 25 years, and food coupons, seedlings, fertilizer, right of intercropping in the given land and technical assistance were also given. Those incentives encouraged them to establish Woodlots by using their labour, time and knowledge. People have the right to harvest timber after the rotation age of 25 years.

Establishment of Farmers’ Woodlots has contributed to increase the tree cover and to conserve the natural forests. By fufilling the objective of establishing those forests, poverty reduction has occurred due to Farmers’ Woodlots. However, growth rates in most Farmers’ Woodlots are poor. In accordance to provincial yield table values, most of the woodlots fall in height class III. In respect of Farmers’ Woodlots, per tree average volume was found to be 38% with regards to provincial yield table values. The major reason for poor growth rates has been the less productivity associated with the lands selected. Mismatching of species and sites, water shortage, uncontrolled burning of weeds have been other reasons for poor growth.

Most of the people participated for Farmers’ Woodlots Programmes, due to early incentives. Therefore, it is obvious that people haven’t been educated well about the importance of the programme. Inadequate monitoring and assistance of Forest Department is another problem which has lead to weak maintenance of Woodlots by farmers. Most of the people who participated to Farmers’ Woodlots Programme have ignored the final or the long-term benefit which is timber. Due to the incentives given, people have completed the planting of seedlings and the maintenance of Woodlots during the first 3-4 years successfully. However, in respect of the long-term benefits, Farmers’ Woodlots Programme has been unsuccessful.

In order to overcome those issues, it can be recommended that planting of Nitrogen Fixing Trees in vacant places after thinning operations, planting of elephant repellent tree species around the woodlots and extending the rotation period for existing woodlots. For newly establishing woodlots consideration of site-species compatibility, use of fast growing species and use of a better monitoring plan can also be recommended.

Challenges faced in establishing eucalypt plantations in Sri Lanka

Challenges faced by the Forest Department in establishing eucalypt plantations in the up country of Sri Lanka

Abstract of a seminar presentation

Jithya Wijesinghe

Eucalyptus was introduced to Sri Lanka in the latter part of 18th century as an exotic species to be raised as a forest plantation species. These were originally raised in the upcountry to produce fuel wood for households and tea industry. But later most of these species were found very promising for railway sleepers and industrial timber. Therefore at present Eucalyptus are planted to meet the requirements of sawn timber, railway sleepers, transmission poles, fuel wood, extraction of essential oils and paper pulp.

Eucalyptus is also planted as windbreaks and shelter belts in certain locations particularly in the upcountry. Beekeeping is another common practice in some areas where eucalypt plantations are raised.

Afforestation of the patana grasslands in the upcountry began in 1930's with planting of E. grandis, E. microcorys and E. robusta in compact blocks on the crests of ridges and hill tops as windbreaks in upcountry.

Environmental issues, social issues, economic issues, accessibility issues, harvesting issues, management issues, unforeseen catastrophes and others are some challenges faced by the forest department establishingEucalyptus plantations in upcountry.

With the sloppy areas, soil erosion was a major challenge that faced by the Forest Department. Furthermore high cost for road constructions, labour cost, encroachment of local people, limited land areas in upcountry, lack of water, high intensity for fire hazards, need of additional effort for soil conservation practices, contours makings are some of challenges faced by the FD.

In order to overcome these challenges establishment of more fire lines, use of soil conservation practices, use of wood aids to protect saplings from wind, enhanced management practices that are used by the FD.

Make harvesting operations well controlled and road guidelines specially in slopes >60⁰, to reduce the wind damage to new plantations, proper grading of seedlings, establishment of water supply programs for field nurseries, enhance the involvement of the local communities to reduce the encroachments are some practices that can be used for further improvement of the establishment of the Eucalyptus plantations in upcountry.

Analysis of the management issues of Dawatagolla Plantation, Sri Lanka

Analysis of the current management issues of Dawatagolla Forest Plantation to make recommendations towards multiple-use forestry
by
Fareena Rusaik and Upul Subasinghe

Since 1940, the historical perspective of forest management shows that the management of forests was carried out with the prime objective of obtaining timber. With the increasing demand for timber, forest plantations help to bridge the gap between supply and demand. Therefore the policy makers in Sri Lanka concentrated to involve rural community through social forestry including fast growing tree species. After 1995, the concept of multiple-use forestry became the centre point of forest management.

It was decided to select the Dewatagolla Forest Plantation (DFP) as the study area. It is situated in Alawwa in Kurunegala District and the extent is 30 ha. It contains of mainly jak and mahogany which are divided into jak working circle (JWC) and timber working circle (TWC).

This study was designed with the objectives of identification of the current management issues in the DFP, analysing the present management plan to test the compatibility and provision of suggestions and recommendations through the multiple-use forest management strategies towards the sustainability.

Data were collected by measurements, questionnaire survey, formal and informal interviews and discussions with the villagers and relavent officers.

Results obtained from the survey indicated the necessity of an appropriate multiple-use forest management practices towards the sustainability. Measurements revealed that the 96% of trees to be removed to implement such management pactices. Therefore a constant approach should be made and selective system of timber management was recommended. Several indigenous and exotic tree species provide multipl benefits to the surrounding community were found through the observations. Furthermore, the willingness of the villagers were also identified for the utlisation of the forest in multiple ways.

Construction of a stem volume prediction model for E. grandis

Construction of a stem volume prediction model for mature Eucalyptus grandis plantation in Pidurutalagala of Nuwara Eliya, Sri Lanka
by
Kandiah Selvarathnam and Upul Subasinghe

Timber volume is the most crucial variable in commercial forest plantations. Therefore a precise volume prediction model was constructed for the mature Eucalyptus grandis plantation located in the Pidurutalagala mountain of Nuwara Eliya District, Sri Lanka.

0.02 ha circular samples were used for the data collection. Breast height diameter (dbh) and total height (h) were measured as the preliminary measurements. Then the stems of the standing trees in the sample plots were divided into sections and section lengths, end-diameters and mid-diameters were measured in order to use the Newton's formular for the stem volume estimations. Altogether 14 samples were used for the data collection.

A basic relationship was then developed by assuming the stem volume (v) can be predicted as a function of h, basal area (g) which is calculated using dbh and site quality as given below.

v = f (g, h, site quality)

In order to represent the site quality, top height and top height / age functions were used. Regression analysis (linear) was used to quantify the relationships. In order to obtain the best models, the variables in the above equation were transformed into different forms that can biologically be accepted. R2 and standard residual distrinbution were used to evaluate the model quality. After a careful study, two models were selected to predict the stem volume of E. grandis trees in the selected plantation.

Effect of diameter on volume measurements of Pinus caribaea

Effect of diameter on volume measurements of Pinus caribaea
by
Samangi Hewage and Upul Subasinghe

Foresters use different methods to estimate the individual tree volume since it is the most important parameter in commercial forestry especially at the mature stage. Among those methods, the most common way is to use Smalian’s, Huber’s and Newton’s formulae. In order to use these three formulae the stem should be divided into sections and volume of each section should be determined separately. Huber’s formula is the easiest one to use because it needs only one diameter measurement of the log. Smalian’s formula needs two diameter measurements while Newton’s formula needs three. Log length is required for all three formulae. Due to the low number of measurements Huber’s formula is more popular among the foresters. However, Smalian’s and Huber’s formulae can introduce errors because they use fewer measurements compared to the Newton’s formula. Therefore the present study was conducted to identify the variation of the error with increasing diameter of trees when Huber’s and Smalian’s formulae are used. Newton’s formula was considered as the one that provides precise values in volume estimation.

Present study was conducted in the 26 year old Pinus caribaea plantation in Yagirala Forest Reserve situated in the low country wet zone of Sri Lanka. In order to represent the whole area of the forest, stratified random sampling method was used and one 0.05 ha sample plot was laid in each stratum (i.e., valley, slope and ridge).

Each tree of the plot was divided into twelve 1m long sections using a ranging staff. Bottom, mid and top diameter of the each section was measured using the Spiegal relascope. Other than above measurements, diameter at the breast height and height of the tree were measured using the diameter tape and the Blume Leiss Altimeter respectively.

In order to find out whether the diameter at breast height affected on volume calculations using above formulae, trees were grouped into two centimeter diameter classes. At each diameter class, volumes estimated using Huber’s formula were tested separately for different section lengths using one way ANOVA. Results indicated that at 95% probability level diameter does not have a significant influence in volume measurements for Huber’s formula up to twelve meter stem length.

First part of this study was conducted to identify the effect of Huber’s and Smalian’s formula in volume calculations without considering the diameter differences of trees in the forest and results proved that Huber’s formula produced least errors when compared with Smalian’s formula. However, in this instance the maximum stem length that can be measured using Huber’s formula became 6m. According to both tests, it can be concluded that Huber’s formula can be use effectively up to 6m stem length in volume calculations with out considering the diameter range of trees.

Plantation forestry in Sri Lanka: Challenges and constraints

Plantation forestry in Sri Lanka: Challenges and constraints

Upul Subasinghe (Presidential Speech, Institute of Biology Sri Lanka AGM, September 2007)

Introduction
At the beginning of the last century, Sri Lanka was a rich country in closed canopy natural forests which covered about 80% of the total land area. However, it has been dwindled up to just over 20% at present which has significanlty increased the awareness of the relevant authorities and the general public. Since the forests are organized assemblages of trees, other plants and animals, in complex association with each other and their physical environment, reduction of forest cover has directly and indirectly influenced on other sub-sectors such as agriculture, wood industry, wildlife etc.

The importance of the forest cover in the aspect of its contribution to the national economy was not clearly identified. In 1993, it has been calculated as 1.4% of the gross domestic product. Employment in the sector was estimated at about 170,000. However, since the use of forests for wood and non-wood products (both goods and services) at village or regional level was difficult to estimate and therefore the true contribution to the economy can however be much greater than the above figure.

Deforestation and causes

On a landscape scale, and over long periods of time, naturally developed forest communities result the greatest amount of biological diversity under the prevailing climatic and soil conditions in a given region. Therefore loosing the natural forest cover causes a severe impact of the existing biological diversity and other intangible uses. In 1995, the forestry sector master plan has identified the following results as the most serious consequences of deforestation and forest degradation.

i. biodiversity reduction,
ii. irregular water flow and drying up of natural streams,
iii. shortened lifespan of irrigation channels and reservoirs,
iv. soil erosion and associated loss of fertility,
v. increasing fuelwood scarcity, and
vi. contribution to the greenhouse gas emissions.

The depletion of forest resources is also closely linked to the demand for forest products such as timber, non-timber forest products and fuelwood. Population increase combined with economic growth has resulted in higher demand for housing and business construction, which has increased the demand for wood.

The poverty has been highlighted as one of the major causes of forest degradation because shifting cultivation, illicit felling and encroachment activities are believed to be results of the poverty. Moreover the government projects implemented in 1980 s such as Mahawely, Kirindioya, Pelawatta Sugarcane plantations and Sewanagala Sugarcane plantations contributed to the forest depletion in significant manner, i.e., between 1983 and 1992 the contribution of the above projects to the deforestation is 37%.

Depletion of the forest cover continues in the future even with a slower rate due to a high demand for timber, non-timber products and the land hunger for settlements and agriculture with the increasing population. The expanding population base and economic growth will increase the demand for roundwood and poles from about 2 million m3 in 1995 to 2.7 million m3 in 2020. During the same period, the need for biomass energy will increase from 9.3 million tonnes to 9.7 million tonnes. At the same time, the closed canopy natural forest cover is projected decline to about 17% in 2020.

Products and services

Other than the wood and non-wood production, the natural forests and forest plantations also provide other environmental services which are demanded by the people. The forestry sector is closely linked to the agriculture and energy sectors. As the population and economy grow, more electricity is needed. Hydropower is the main source of electricity. Therefore, maintenance of the forest cover has become a must to continue the sustainable productivity of the above sub-sectors.

However, the country's wood demand should also be addressed by utilizing the forest resources. Among the highly demanded forest products, sawntimebr, roundwood and fuelwood become more important. Although sawnwood consumption in Sri Lanka (31 m3 per 1000 persons in 1993) is lower than that of the other countries in Asia such as Malaysia, Thailand, it has been projected to be 0.885 million m3 in 2020, i.e. by about 12,600 m3 per year assuming that some substitution of other materials for sawnwood is taken place. According to the forestry sector master plan, the industrial roundwood requirement in 2005 was about 15.61 x 105 m3 which is projected to be more by 4.62 x 105 m3 in 2020,due to the growing demand arisen by the increasing population.

Per capita consumption of paper and paperboard consumption is also low in Sri Lanka when compared with the international figures. However, the demand for paper and paperboard is projected to reach 407,000 t in 2020 compared with 130,000 t in 1993. The average annual growth in total paper and paperboard demand is forecast to be 4.3% (9400 t). Per capita consumption in 2020 will be about 18 kg per year.

Although there are not proper statistics available on the non-wood forest product consumption, most of the population in Sri Lanka uses those products directly or indirectly. Among the mostly used products, medicinal plants, rattan, bamboo, kithul products and wildlife products are prominent.

Electricity and telephone poles are more important in terms of value than in terms of wood consumption. The long-term annual demand for wooden electricity poles is expected to stay at 20,000-25,000 pieces (about 3000 m3), in spite of extensive electrification schemes. However, there will be a very little demand for wooden telephone poles in the future.

The contribution of the natural forests to the bio-fuel supply is 7% which is 4% by the forest plantations. The country's bio-fuel requirement in 2020 will be 0.889 million m3. However, there might be a change of this figure in the future due to the increase of use of LP gas and electricity. Moreover, although Sri Lanka is self-sufficient in fuelwood supply as a country, there are fuelwood deficit regions such as Colombo, Matara, and Nuwara-Eliya. Therefore, unless a proper distribution system is introduced, use of fuelwood will also become a major problem.

Forest plantations

In order to address the timber and fuel-wood demand in the country, forest plantations were introduced as the alternatives. One of the other objectives formulated at present is that to address the issue on timber imports from the other countries such as Malaysia. Forest plantations were established for the first time in the 1870s, although most of the planting has taken place since the 1950s. Within that period, about 89,000 ha of forest plantations of varying quality have been established. This area comprises some 5000 ha of mainly fuelwood plantations, which were mainly under the control of tea estates and a tobacco company. In 2004, Sri Lanka Forest Department maintained 93,000 ha of plantations in the entire Island.

Forest plantations in Sri Lanka have mainly been established using exotic species due to their faster growth rates over the indigenous species. Although the history of introducing exotic timber species goes back to 1870s, most of the planting has taken place since the 1950s. The idea of this exercise was to have an alternative timber resource to protect the existing natural forest cover and to rehabilitate the environmentally damaged areas within a short period of time. At present the most favourable species for the plantation forestry are teak, eucalypts, pines, acacias and mahogany.

Although the primary aim of the establishment of forest plantations are to address the timber and fuel wood demand, there are other benefits which might be similar to some of the benefits that are obtained from the natural forests as given below. However, the biodiversity and some of the environmental values cannot be met in the forest plantations especially managed for the timber production. These benefits are:

i. increase of wood production,
ii. savings in the government expenditure,
iii. improvement of landuse,
iv. reduction of the pressure on the natural forests,
v. reduction of timber imports,
vi. increase of revenue for the state, and
vii. increase of rural incomes and employment.

Forest plantations under state control will have to provide a reasonable return to society in order to mark them as true production forests, and as the minimum, the benefits accruing to society should not be lower than the costs. Tree growing has to provide higher return than agriculture before a farmer is interested in investing in it, because of the longer production period and greater risks involved. Private sector investors always have investment alternatives, and wood production still has to demonstrate its potential as a viable investment in Sri Lanka.

The profitability of small scale plantations managed by farmers was assessed by assuming that the yields would be 20% less than in a large scale plantation. According to the financial analysis, small scale monoculture plantations would not be profitable for farmers. The real rates of return of all the selected species under normal site conditions were clearly below the indicative real rate of return (20%) that a farmer would acquire. However, the results do not mean that the small-scale forest plantations would not be established by the farmers under right conditions. When trees are planted on small scale or incorporated into the farming system, tree growing can be a profitable proposition, as is demonstrated by the dynamic home garden sub-sector that is providing wood for the industry, and valuable income and raw material to the farmers.

Involvement of private sector in plantation forestry

In order to increase the tree cover by means of forest plantations to address the earlier mentioned requirements, and to save the government funds for other necessities, the private sector participation for the establishment of forest plantations has been promoted. However, due to the longer duration that has to be waited to obtain the profits, until recent, investments in forestry sector was not popular among the private sector. However, almost all the major regional planting companies (i.e., tea and rubber) stepped forward initially and started planting timber species on their barren and abandoned lands in both upcountry and low country for the production of timber in addition to the already maintained fuelwood plantations. However, the view of the government was not only to focus the improvement of the existing plantations but also on involving the non-estate sector in the establishment and management of new plantations. At the same time the state has recognised the necessity of supporting policy, legislation and other support systems such as extension and access to financing are in place.

Management of forest plantations

Managed forests are generally less complex than natural forests because management typically attempts to optimize only a few species - usually those of high commercial value; those which are characterized by fast growth (high productivity); or those that can be grown in pure stands or in relatively simple mixtures.

Villages in forest concessions, timber harvesting, timber industry and population are closely linked. This means that sustainable forest use and agriculture are also closely linked. However, the private sector engaged in timber harvesting, timber industry, job creation cannot take care of agriculture. Agriculture is a completely different branch with a different approach and different expertise. To harmonise both - forestry and agriculture - government support is necessary, and governments need the support of donors in order to integrate forestry/agriculture in projects with research and education. However, it has been recognised that the private investors have to respect the existing laws and traditional rights especially at the harvesting period. Requests by the population for better regional infrastructure and road-building are followed by private companies when supported by government authorities and financially feasible.

Challenges in plantation forestry

The planetary ecosystem at present may have a minimum threshold of forest cover necessary to support a certain level of human habitation. Mostly, foresters assume that an existing, desirable forest cover type can be maintained by the same silvicultural treatment that was successful in another area or on another site. This, of course, may not be so if the two stands exist on significantly different site types or have resulted from different disturbances.

Furthermore, as emphasis in forest management changes from simply trying to grow the "best trees" on "the best sites" toward maintaining forests in a more natural condition while still utilizing the resources, it is becoming even more important that attention has to be paid to the physical environment that controls forest ecosystems. One of the reasons for this change may be due to the understanding of the environmental safeguards or due to the recognition of the importance of the requirement of the standards such as forest certification.

Forest certification has been introduced to promote the sustainable forest management with the protection of existing biodiversity. However, medium and small companies will not be able to cover the costs of certification because there is no guaranteed price increment for the certified timber at the world market at present. Moreover, the opportunity to export the Sri Lanka timber to the countries interested in certified products is low under the present government policy. This means that these markets have to bear certification costs alone or five times more than other markets not bearing those costs. In addition to higher production costs for improved sustainable forest management, the growers will have to bear quite important costs for certification.

Constraints in plantation management
Forest management is a complex exercise due to the web factors involved with it other than the economic, ecological and cultural aspects. There is also an involvement with the technical aspects, institutional rules, political influences which are decisive for the behavior of the user of natural resources in general and of the forest in particular. In constitutional states these limits and possibilities for owners and users are fixed in legal acts, such as constitutions, laws, decrees etc.

Among the major constraints faced in plantation forestry, the land availability, social issues, environmental issues, lack of scientific information and research become prominent. At the same time, the unforeseen catastrophes create significant problems by reducing the growth rate or destroying a part or the entire forest.

Availability of land

Land availability, sustainability and the profitability of plantation forestry are major issues if industrial plantations are to be established in new areas. Locating large new areas for forest plantation development will not be a very easy task. In the more productive wet zone and up country areas, competition for land is intense and the forest plantation sector cannot expect to acquire significant additional land unless they are taken from other uses. Availability of the suitable lands is the main constraint faced by the private sector investors at present. Mostly the available lands are infertile or abandoned after planting agricultural crops such as rubber. Obtaining a suitable land with a large extent is more problematic in the wet zone. In order to obtain a higher growth from infertile lands, most intensive management practices have to be applied which can increase the cost significantly. It will also take time to reach high quality productivity levels on such lands. The expected final harvest of the private forest plantations are much shorter than that of the Forest Department plantations and therefore more and more financial inputs may be necessary to uplift such plantation conditions.

Social and environmental impacts and risks

Management practices that are ecologically sound on a site or local ecosystem level may not address landscape and regional concerns. Although private owners are not obligated to consider regional ecological concerns (other than those specifically covered by law, e.g., harvesting of endangered species, harvesting on high slopes or sensitive areas), many of them are interested, and often eager, to accommodate them within limits of economic efficiency.

Environmental issues
Plantation forestry especially with even-aged monocultures is criticised in causing environmental degradation. The situation becomes more severe with the exotic species such as pines and eucalypts. With those plantations, the issues have emerged on degradation of the soil quality especially when they are planted on slopes. Lack of biodiversity in such forests is also common. Moreover, there are issues regarding the aesthetic values. The erosion problem becomes severe if the plantations are clear felled after reaching the maturity. Therefore the necessity of a system to protect the soil quality by using proper management schems is always highlighted.

Unforeseen catastrophes
Unforeseen catastrophes are common in forest plantations. In Sri Lanka the major damage is caused by the fire, diseases and pests. Teak in the dry zone and eucalypts in the up country are vulnerable for fire. Teak is commonly attacked by the defoliators and the skeletonizers at the nursery stage and very young stage in the field. However, mahogany is considered as the best example for vulnerable plantation species for the insect attack that can be caused by shoot borer called Hypsophylla.

Lack of scientific knowledge and research

This has become a serious issue for the private investors on plantation forestry. In order to make their plantations economically viable, the age for the final harvest for both mahogany and teak which are the preferred species by them, has been decided around 20 years which is significantly lower than the state plantations. Therefore, they have to use the most intensive management principles to achieve the expected growth within the given period. In order to facilitate these requirements, enough studies of growth rates, growth enhancement, site quality differences, and protective measures from pests and diseases are yet to be conducted.

Conclusion

Two things are clear concerning comprehensive and newly strengthened national programmes to sustain forests: they must be country-driven and country-initiated; and they will, in many countries, require new and more effective international support. Sustaining forests can best be achieved through a combination of national and international policy reforms, long-term plans to stabilize forest areas and industrial countries' commitment of greatly enhanced financial and technical support to developing countries.

The investor-institute partnership should be maintained in order to achieve the goals set in the plantation forest management and a flow of information from one sector to the other should be established. Moreover, partnership agreements could specify the actions to be taken by countries inside and outside the forest sector to address the underlying causes of deforestation and the support and actions to be undertaken by the international community.