Effects of carbofuran on survival and growth of Duttaphrynus melanostictus tadpoles
By lakmali | March 4, 2010
M.R. Wijesinghe, B.A.D.M.C. Jayatillake and W.D. Ratnasooriya
This study investigated the impact of a commonly used carbamate pesticide, carbofuran, on survival, growth, development and activity of larvae of the Asian Common Toad, Duttaphrynus melanostictus Schneider 1999. Continuous exposure trials of 15 days were conducted using tadpoles of Gosner stages 24-25 with a commercial grade carbofuran (Curaterr 3G). Four concentrations 50, 150, 250 and 500 μgl-1 were tested and treatments and controls (without pesticides) were maintained in triplicate (n=56 per treatment or control). Results revealed that there were marked elevations in mortality in larvae exposed to all tested concentrations as compared to those in the controls. Mortality was, however, not dose-dependent, but depicted a hermetic response, where mortality at 500 μgl-1 (35 %) was much lower than that recorded at 250 μgl-1 (62 %). The 15day LC50 value of D. melanostictus larvae was 190 μgl- 1. In contrast to mortality, the effects on growth, development and activity although pronounced, were transient. For instance growth impairments were noted until day 7, but the body size of surviving tadpoles were comparable to those in the controls by the end of the trial. Exposure to carbofuran to concentrations of 150 μgl-1 and above also caused several notable morphological aberrations such as swollen heads and thin tails. In particular, the fact that carbofuran induced high levels of mortality at the tested concentrations, which are below the field application levels, suggest that this pesticide may be detrimental to the survival of amphibians inhabiting agricultural landscapes in Sri Lanka.
M.R. Wijesinghe, B.A.D.M.C. Jayatillake and W.D. Ratnasooriya
Department of Zoology, University of Colombo, Sri Lanka.
Topics: Biodiversity, sympoisum 2009 | No Comments »
Diversity and microhabitats of termites in a natural and a secondary forest in Hantane hills, Kandy District
By lakmali | March 4, 2010
I.I. Hemachandra, 1,2, J.P. Edirisinghe 1, W.A.I.P. Karunaratne 1, C.V.S. Gunatilleke3
Termites (Isoptera) are the most important decomposers in tropical rain forests and are vital in maintaining nitrogen and carbon cycles. They are sensitive to disturbances, especially to forest canopy losses and hence are one of the important bioindicator taxa. The documented termite fauna of Sri Lanka is represented by 58 species in 28 genera. Research studies on termites of forests are few in Sri Lanka. Objective of this study was to determine the species composition, diversity and microhabitats of termites in a selected natural and a secondary forest in the Hantane hills.
The Hantane range is a series of hills, about 432 ha with an elevation between 518-1110 m. During the British period Hantane land was opened up for coffee, tea and rubber plantations. The selected study sites included patches of natural forest at > 1000 m elevation and a secondary forest, comprising mixed species, at elevations between 700-1000 m. A belt transect (2×100 m) was laid in each site for sampling termites. Each transect was divided into 20 (2×5m) sections and each section was sampled by 2 persons for 30 min. The number of encounters with termites (hits) of a given species within a transect was taken as the relative abundance of that species within that transect. An encounter is the presence of a species in one transect section (5×2 m). Termite diversity was compared using Shannon Diversity Index. Termites were also collected randomly from several areas within the two forest types for species determination.
A total of 11 termite species were collected from the two forest types using both methods. They are: from the natural forest Ceylonitermellus hantanae (Holmgren) (soil-wood interface feeder), Dicuspiditermes incola (Wasmann) (soil feeder); and from the secondary forest Odontotermes ceylonicus (Wasmann), O. globicola (Wasmann), O. horni (Wasmann) (all fungus growers and feeders), Nasutitermes fletcheri (Holmgren & Holmgern) (soil-wood interface feeder) and 5 unidentified species of Odontotermes Holmgren ( fungus growers and feeders) . A lower species Diversity Index was obtained for natural forest (H’= 0.683) compared to secondary forest (H’=1.630). The composition of termites species showed a marked contrast with none of the species in the natural forest being represented in the secondary forest and vice versa. The most common species in the natural forest was the endemic C. hantanae and in the secondary forest, the unidentified Odontotermes sp. 2.
A significant observation in both forests was the absence of termite mounds as well as long runways along live trees that lead to arboreal nests. The two termite species recorded from natural forest are subterranean nest builders that inhabit soil. The termites of the secondary forest inhabit soil, leaf-litter and wooden material like, tree stumps, logs, fallen branches and twigs. Termites of the fungus growing genus Odontotermes was confined to the lower altitudes.
A distinct difference in termite species composition, diversity and microhabitats was recorded from the two forest types, suggesting that altitude and temperature, among other factors may be influential environmental variables for termites.
I.I. Hemachandra, 1,2, J.P. Edirisinghe 1, W.A.I.P. Karunaratne 1, C.V.S. Gunatilleke3
1Department of Zoology, Faculty of Science, University of Peradeniya, Sri Lanka2Postgraduate Institute of Science, University of Peradeniya, Sri Lanka3 Department of Botany, Faculty of Science, University of Peradeniya, Sri Lanka.
Topics: Biodiversity, sympoisum 2009 | No Comments »
Comparison of sampling techniques to estimate tree diversity and aboveground biomass in Sinharaja forest Sri Lanka
By lakmali | March 4, 2010
M.D.P. Kumarathunge, R.O. Thattil, S.P. Nissanka and P. Pathinayaka
The use of correct sampling techniques is of paramount importance since the precision of estimates greatly depends on it. Different methods of sampling have to be investigated to find out the best sampling technique for a given situation. This study was conducted to determine the best sampling technique to estimate tree diversity and aboveground biomass in Sinharaja forest.
Tree sampling techniques, such as quadrat method, transect method, and point centered quarter method PCQ) were evaluated in this study. A total of 25, 15×15 m plots for quadrat method, eleven, 5×100 m strips for transect method and 120 sampling points for PCQ method were used for sampling. All stems greater than 5 cm diameter at breast height (DBH) were taken in to consideration and their species level and the tree height, DBH was recorded. Sampling techniques were compared for tree density, basal area, tree size distribution, aboveground biomass and diversity indices estimated by each technique. A simulation was done to estimate the minimum sampling area required to assess the number of tree species of the study area.
According to the results, PCQ method gave the highest precision for most of the parameters estimated. There were no significant variation between the parameters estimated by PCQ method and quadrat method for most of the situations. PCQ technique recorded the highest number of species per 100
individuals enumerated (18.12%). The negative exponential functions fitted for the species - area (quadrat method) and species – point (PCQ method) relationships estimated that the minimum sampling area required to assess the number of tree species (in an area of 50 ha) of Singharaja forest as 6000 m2 for Quadrat method and 160 sampling points for PCQ method. But it was difficult to estimate the minimum sampling area required to estimate the above ground biomass in Sinharaja since there was no underlining relationship between biomass and number of sampling units.
The results of the study emphasized that the PCQ method is a precise sampling technique that can be used to estimate the tree density, tree diversity and above ground biomass in natural forests. The random distribution of individuals is not necessary for tree diversity and biomass estimation by PCQ method if the site stratification and random placement of sampling points in the study area are performed. Considering the highest precision of estimates and the saving of time and cost, the PCQ method can be recommended as an effective sampling technique for tree diversity and biomass studies.
M.D.P. Kumarathunge, R.O. Thattil, S.P. Nissanka and P. Pathinayaka
Department of Crop Science, Faculty of Agriculture, University of Peradeniya, Sri Lanka.
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Effects of urea and adult palm fertilizer mixture on the survival and body wall tissues of the earthworm, Pheratima hawayana
By lakmali | March 4, 2010
O.K.C. De Silva and W.U. Chandrasekera
We carried out a laboratory experiment to find out the effects of urea and urea containing Adult Palm Mixture (APM) fertilizer on the percentage of survival and body wall tissues of one of the commonest earthworms, Pheretima hawayana.
In this experiment, twenty plastic dishes with the dimensions of 510 cm2 area and 10cm height were filled with a soil mixture prepared by mixing dried cow dung into wet soil. The containers were grouped into five batches and urea solutions were added evenly into each batch at a rate of 0, 0.1, 1.5, 3.0 and 16.2g per container. Later, a batch of 15 healthy earthworms was introduced into each container in each treatment and, their % survival was determined weekly for a period of four weeks. The pH, organic matter content, temperature and the moisture content of the test soil were also measured using standard methods. The experiment was repeated for APM fertilizer at a rate of 0, 1, 2.2, 5 and 21.6g per container in each replicate treatment.
Results revealed that the % survival of earthworms was significantly low at the highest concentration of urea or APM fertilizer. Further, the % survival of earthworms decreased significantly in both fertilizer treatments by the third week of exposure. A significant drop of pH was also noted in these containers. Histological sections of earthworms in the control revealed normal intact architecture of the body wall. However, it showed lesions and epithelial detachment from the underneath muscle layer upon exposing to high concentrations of urea or APM fertilizer mixture causing mortality among them.
Although the use of artificial fertilizers is imperative to meet the current demand of the crop yield, it is evident that the correct use of their recommended concentrations is of vital importance to the survival of earthworms whose presence is indeed helpful to increase the soil fertility.
O.K.C. De Silva and W.U. Chandrasekera
Department of Zoology, University of Kelaniya, Sri Lanka.
Topics: Biodiversity, sympoisum 2009 | No Comments »
Investigation of ergonometric parameters of university lecture hall furniture
By lakmali | March 3, 2010
U.L. Palamakumbura and H.S. Amarasekara
Sitting comfort is considered important particularly in working environments with regards to health and performances of day to day work. Sitting on a comfortable seat helps to relax the body and reduce energy consumption but on the other hand prolong sitting slackens abdominal muscles and may cause backache. Application of ergonomic approach to furniture designing helps to increase the comfort of furniture.
There has been an inherent in Sri Lanka on ergonomics of furniture designing (Abeysekara, 1982 and Silva 2006). No considerable attention has been given on ergonomics of universities or school furniture. It is important to concentrate on furniture in lecture halls and class rooms because children are spending a long period of their lives in schools and university working environments. The present study aimed at investigating of ergonomic parameters of lecture hall furniture of USJP (University of Sri Jayewardenepura). Though, the investigation has been done for Faculty of Applied science (FAS), the results can be applied to the whole university. The FAS of USJP has eighteen lecture halls and these eighteen lecture halls consist of four major types of furniture designs. A distinct variability was observed in the all ergonomic parameters of furniture in eighteen lecture hall. Most variability was observed in height of the back rest.
Furniture in each lecture hall of FAS was compared with the developed ergonomic standard values. Many mismatches were observed between standard ergonomic parameters based on anthropometric data with the ergonomic parameters of present lecture hall furniture in FAS. This may cause many health problems like back pain, neck pain and fatigue of university students. Seat height of the university lecture hall furniture of FAS does not match with the popliteal height of the students.
Furthermore, the user survey shows several problems regarding comfort of university lecture hall furniture. Students do not like fiber glass chairs with desktop arm rest at the right side and the ergonomic parameters (seat height, seat width) do not comply with the student’s body dimensions. None of the seating units in FAS fulfilled all the ergonomic parameters.
Positive remarks were given by the students for lecture hall P1 and M1. Based on anthropometric data of university students in FAS ergonomic parameters were proposed. Recommended ergonomic parameters are 42.5-43.5cm for seat height, 45-46cm for seat depth to back support, 16-17cm for height lowest point back support, 37-38cm for height highest point back support, 37-38cm for seat width, 54-55cm for vertical span below the table and 63-64cm for horizontal clearance below the table.
U.L. Palamakumbura and H.S. Amarasekara
Department of Forestry and Environmental Science, University of Sri Jayewardenepura, Sri Lanka.
Topics: Resource Management, Social aspects, sympoisum 2009 | No Comments »
Evaluation of benefits that can be obtained from FSC certification
By lakmali | March 3, 2010
K.M.T.S. Jayarathne and S.K.Pathirage
Forest Stewardship Council (FSC) is an international non-profit, multi-stakeholder organization established in 1993 to promote responsible management of the world’s forests. FSC offers a comprehensive set of universally applicable requirements for responsible forest management with its 10 Principles and 56 associated Criteria. Achieving FSC can be further divided into standard setting, independent certification and labeling of forest products. There are three types of FSC certifications. They are FM, CoC and Group Certification. Forest managers or owners who want to prove that their forest operation are socially beneficial and managed in an environmentally appropriate and economically viable manner can apply for forest management (FM) certification. FSC chain of custody traces FSC certified timber throughout the production chain.
The expenses for a successful certification of forest management can be divided into (i) costs for an enhancement of sustainability, (ii) costs for audits (these are controlled by third parties) and (iii) secondary costs (e.g. losses of stumpage revenues). All together, the effective costs for FSC certification my be between 2.6-19.1 •/ha. The costs and timescale for CoC certification vary depending on the size and complexity of the operation. It also depends on the range of products and processes.
The benefits of certification are for the most part indirect, although surely valuable. They can include a better professional image, improved worker safety and training, better records, more active public involvement, better morale among forest managers, enhanced knowledge for outreach and extension, better environmental management systems and greater timber prices or access to more markets. As part of receiving certification, we have had to make significant improvements in several areas, such as (1) establishing a transparent and consistent environmental management system and record keeping process for our forests; (2) improving training and record keeping for forest workers using equipment and chemicals on the forest; (3) improving our adherence to and implementation of state forestry Best Management Practices (BMPs); (4) enhancing or at least clarifying our polices regarding silvicultural prescriptions and utilization standards; (5) identifying natural areas and wildlife habitat requirements for management; (6) enhancing the forest data bases, GIS coverage, and allowable harvest levels; and (7) developing more explicit procedures for public involvement and input into forest management decisions. The aim of certification is to ensure that forest resources are managed to meet the Social, Economic and Ecological needs of present and future generations. FSC prohibits conversion of natural forests or other habitats into forest plantations, prevents the use of highly hazardous pesticides, avoid the cultivation of genetically modified trees (GMOs), and respects the right of indigenous or local people in the area and health & safety of the workers. Other than that certification ensure the provision of clean water, fresh air and even help combat global warming. It also protects food, medicine and important natural resources as well as biodiversity. When it comes to economic benefits, evidence of increased market access or price premiums is more circumstantial. According to information provided by UNECE and FAO, market price premiums between 12% - 20% can be obtained for FSC-certified sawn hard woods.
K.M.T.S. Jayarathne and S.K.Pathirage
Control Union Inspections (Pvt) Ltd., Colombo –7, Sri Lanka.
Topics: Plantations, Resource Management, sympoisum 2009 | No Comments »
Comparison of wood quality of even-aged Teak (Tectona grandis L.f.) plantations in three districts of Sri Lanka
By lakmali | March 3, 2010
D.P. Weerasinghe and H.S. Amarasekara
Teak is listed as a super luxury timber in Sri Lanka and it has a high demand from construction and furniture industries. Teak hardwood is highly durable. It is an exotic species and, almost all teak plantations are located in dry and intermediate zones of the country. There are about 35,000 ha of teak plantations and most of these plantations are managed by the Forest Department. These plantations are distributed throughout many administrative districts in the country. Despite of its importance as a high-demand species in the market, there have been limited or no research studies conducted to assess the wood quality of teak grown in different districts.
This study compares the wood quality of even-aged teak plantations in three districts of Sri Lanka, i.e., Anuradhapura, Kurunegala and Ratnapura teak from Ratkarawwa area (Ratnapura district) was specially selected for comparisons, since there is a general belief among people that Ratkarawwa produce superior quality teak in comparison to other teak growing areas of the country.
Quality of teak wood was assessed by analyzing specific gravity and percentage of heartwood. Ring width was taken as the indicator of growth rate.
Three 45-year old trees of 45 grown in state plantations were examined in this study. Sample disks were extracted at breast height from each tree. Ring width and specific gravity of each ring was measured. The mean ring width values recorded for trees from Anuradhapura, Kurunegala and Ratnapura districts (A=2.679mm, K=2.652mm, R=3.106mm) did not differ significantly. The mean specific gravity values of trees from three districts (A=0.6142, K=0.6587, R=0.6901) were statistically significant. It was also observed that there is no significant relationship between ring width and specific gravity in the three districts. Heartwood percentage and wood colour were also analyzed to illustrate wood quality.
Slightly higher specific gravity value and high heartwood percentage were observed in Ratnapura teak. Furthermore, growth rate is high in this area and it contributes towards gaining high timber volume.
According to timber characteristics investigated in this study, it can be inferred that Ratkarawwa area (Ratanapura) produce high quality teak in comparison to the other two districts and, economically good teak wood are produced by plantations in Ratanapura district. However, other areas are also capable of producing good quality teak timber.
D.P. Weerasinghe and H.S. Amarasekara
Department of Forestry and Environmental Science, University of Sri Jayewardenepura, Sri Lanka.
Topics: Forest Management, Plantations, sympoisum 2009 | No Comments »
Estimation of biomass carbon of Eucalyptus grandis using IRS LISS III Satellite images in up country wet zone of Sri Lanka
By lakmali | March 3, 2010
A. Gunawardena1, S.P. Nissanka2, N.D.K. Dayawansa3
There are vital needs to collect some necessary data on forest plantations to address the global climate change that includes carbon sink concept in Kyoto protocol. There are very rapid expansions of forest plantation in Asia-Pacific region and Sri Lanka also have a large extent of forest plantations such as Eucalyptus and other fast-growing species. Plantations and Plants may be viewed as “Carbon sinks” removing CO2 from atmosphere and oceans by convert it into biomass in stem, root and foliage. Biomass is assimilation and accumulation of carbon into organic matter determined by carbon fixation and carbon release, therefore, biomass can be predicted by modelling of carbon dynamics. Estimating woody biomass by allometric equations may be time-consuming, because of the need to remove sample trees at the target research site, and the cutting may adversely affect the site. Therefore, there is a need to develop methods for estimating the biomass of managed plantations at diverse sites simply with non-destructive methods.
Use of Satellite Images Vegetation Index (SIVI) models can processes the biomass estimation without tree destruction by taking forest stand parameters as inputs such as Diameter of breast height (dbh), total tree height, canopy cover percentage, and ground exposure and slope parameters. Therefore, this study is an attempt to develop satellite driven 3 vegetation models to estimate above ground biomass and carbon content of Eucalyptus grandis which cultivated in up country wet zone region of Sri Lanka. The Eucalyptus grandis sites are located in the Pattipola, Ohiya and Meepilimana areas in Nuwara Eliya district of Central Province of Sri Lanka. Stratified random sampling plots were selected to obtain forest stand parameters and another few plots were used to accuracy assessment. Trees were sampled by putting 25×25m temporary sample plots which matching to the satellite image pixel resolution (area 625 m2). Biomass and carbon stocks are estimated from DBH and combination of total height using locally relevant allometric equations.
The estimated above ground biomass and carbon content value of the each plot were correlated with developed satellite driven vegetation indices (Normalized Difference Vegetation Index (NDVI), Soil Adjusted Vegetation Index (SAVI) and Liner Transform Band). The results show the NDVI derived from IRS LISS III satellite image is significantly correlated with the above ground stored biomass carbon content than other two indices. Finally biomass and carbon content map was developed for the study area using IRS LISS III satellite images.
A. Gunawardena1, S.P. Nissanka2, N.D.K. Dayawansa3
1Postgraduate Institute of Agriculture, 2Faculty of Agriculture, University of Peradeniya, 3Faculty of Agriculture, University of Peradeniya, Sri Lanka
Topics: Plantations, Resource Management, sympoisum 2009 | No Comments »
Forest woodland ecosystem: An insight into the addition of litter through teak plantation
By lakmali | March 3, 2010
A. K. Mani, S. Manivasakan, S. Vijayabaskaran
Teak is an important tree species grown under plantation conditions for timber requirement. Being a deciduous tree, it favours for accelerated nutrient cycling. A field experiment was conducted in an eighteen year old teak plantation at Forest College and Research Institute, Mettupalayam, Tamil Nadu, India to study the litterfall, their composition and rate of decomposition. The litter collected were separated into leaf litter, flowers, fruits and twigs. All were subjected to decomposition by using nylon bag technique. The total annual litterfall accounted for 11,255 kg ha-1. Of the total litter, leaf fall in a year was 9216 kg ha-1 (81.9%) followed by 726 kg ha-1 (6.5 %) by twigs, 707 kg ha-1 (6.3 %) by fruits and 607 kg ha-1 (5.3 %) by the flowers. Among the litter components, flowers decomposed rapidly than the other components. The highest decomposition constant (K) was recorded for flowers (2.39) and the least for fruits (0.70). The per cent remaining of the absolute amount of dry matter of leaf litter, flowers, fruits and twigs after one year of decomposition was 17.3, 9.2, 49.5 and 19.6, respectively.
A. K. Mani, S. Manivasakan, S. Vijayabaskaran
Regional Research Station, Tamil Nadu Agricultural University, India
Topics: Forest Management, Plantations, sympoisum 2009 | No Comments »
Growth, biomass and carbon accumulation among rubber (Hevea brasiliensis), teak (Tectona grandis) and mahogany (Swietenia macrophylla) A case study from 1 to 10 Years of Age Series
By lakmali | March 3, 2010
N. Appuhamy1, L. Samarappuli2 and S. Karunaratne1
The study was conducted to compare the biomass accumulation and carbon stocks among rubber, teak and mahogany. Above Ground Biomass of each species were calculated using the allometric models. Mean total tree height of rubber, teak and mahogany were ranging from 0.87 m to 20.32 m, 3.41 m to 11.05 m and 1.65 m to 7.53 m, respectively, between 1 to 10 years of age. For height and age, regression logistic standard curves were fitted to teak, rubber and mahogany with the R2 of 0.845, 0.916 and 0.921 respectively. The mean dbh of rubber, teak and mahogany were varying from 2.19 cm to 19.63 cm, 1.97 cm to 12.84 cm and 1.75 cm to 8.14 cm, respectively, within the selected age series. Exponential curves for rubber (R2=0.976) and teak (R2=0.915) and logistic curve for mahogany (R2=0.913) were fitted for dbh vs. age. Mean total tree biomass and carbon stock in rubber were significantly higher from other two species in all selected age series, except first year; biomass and carbon stock varying 0.89 kg/tree to 262.61 kg/tree and 0.45 kg/tree to 131.30 kg/tree, respectively. For other two species, it was ranged from 0.74 kg/tree to 88.87 kg/tree and 0.37 kg/tree to 44.35 kg/tree for teak and 0.49 kg/tree to 23.83 kg/ tree and 0.24 kg/tree to 11.91 kg/tree for mahogany. For Biomass and age regression logistic, critical exponential and exponential standard curves were fitted to rubber (R2=0.965), mahogany (R2=0.862) and teak (R2=0.874). The relationship of Height vs. dbh showed a high degree of association for rubber (R2=0.918), teak (R2=0.859) and mahogany (R2=0.976). Moreover, the relationship of biomass vs. height recorded a high degree of association for rubber (R2=0.911), teak (R2=0.862) and mahogany (R2=0.962).
N. Appuhamy1, L. Samarappuli2 and S. Karunaratne1
1Department of Plantation Management, Faculty of Agriculture and Plantation Management, University of Wayamba, Sri Lanka 2Department of Soils and Plant Nutrition, Rubber Research Institute of Sri Lanka.
Topics: Forest Management, Plantations, sympoisum 2009 | No Comments »