Relative importance of salinity regimes and neighbor competition on vegetation dynamics in Sundarbans mangrove forest, Bangladesh: An individual-based model approach

M. N. I. Khan and U. Berger
Department of Forest Biometry and Systems Analysis, Institute of Forest Growth and Computer Sciences, Technical University Dresden, Germany

Along with the global depletion of mangrove ecosystems due to over-exploitation and other anthropogenic activities, sea level rise due to climate change may exert a potential impact to the salinity regimes in mangrove ecosystems. Sundarbans mangrove forest in Bangladesh shows distinctive vegetation composition in three salinity zones, e.g., fresh water, oligohaline and polyhaline zones, as the forest partially receives upland fresh water flow by the Ganges. Information on mangrove succession and the ecological processes behind it is still little known because of absence of long term monitoring data in this regard. Nevertheless, such information is important in understanding ecosystem processes and in analyzing forest planning and management options.

In this study, we evaluated the impact of different salinity regimes and inter-and-intra- specific competition on vegetation composition in Sundarbans and analysed the results in the light of succession, based mainly on simulated data and empirical data as well. For the purpose of simulation experiments, the KiWi mangrove model was parameterized in this study to a South Asian as well as tropical mangrove forest (Sundarbans) for the first time and it was found suitable to extract information on vegetation dynamics. The most dominant four mangrove species (Heritiera fomes Buch.-Ham.; Excoecaria agallocha L.; Ceriops decandra (Griff.) Ding Hou; Sonneratia apetala Buch.-Ham) were taken into account for this study. We used the simulation model to understand how species-dependent growth rate, salt tolerance and shade tolerance lead to the observed patterns in horizontal and vertical forest structure in Sundarbans. Our study will enrich scientific knowledge on mangrove structure and dynamics, which in turn will help building the adaptation measures to mitigate the adverse impacts posed by sea level rise to Sundarbans.

Key words: KiWi model, mangrove succession, simulation experiment, slat tolerance, shade tolerance

Restoration of sand dune vegetations after the Tsunami in Cuddalore, SouthEast coast of India

M. S. Muthukumarasamy and K.D. Kaliyaperumal
Faculty of Marine Science, Annamalai University, India

Sand dune plants or psammophytes include creepers like beach morning glory (Ipomea pescaprae) and sand spinifex (Spinifex littoreus). These vegetations serve as binding agents to form sand dunes which in turn act as a shelter for some marine animals during the breeding season. The sea turtles lay eggs in such sand dunes.  Moreover, the sand dunes also protect the coast from the waves by lessening the force of the oncoming waves.

These plants are threatened due to the construction of roads, formations of groynes and conversion of the coast into a tourist destination.  This occurs at Cuddalore, Silver Beach also.  A preliminary restoration work was under taken during the post-tsunami period and sand dune vegetation has been successfully restored in a few places on the Silver Beach of Cuddalore.  Propagation of I. pescaprae was done by plucking a portion of the creeper and planting it in pits dug at a depth of 30 to 40 cm. Three places were selected for restoration with 6m x 6m.  The planting of creepers were performed at an interval of 2m distance each in 6 pits.  The growth rate of the creepers was found to be 60 cm in length within two months.  The overall survival was 80%.  The plants were nurtured without any fertilizers except watering once in a week.  Fencing was made to protect the study area. Ideal season for the culture of Ipomea pescarprae in the sand dune area is the northeast monsoon period.

Key words: sand dune vegetation, Tsunami, coastal ecosystem

Diversity and distribution of mangrove flora in the Attaragoda wetland, Galle with some notes on avifauna

B. Jayasekara1, I.R. Wedage2 and P. N. Dayawansa2

Attaragoda is a mangrove wetland situated in the Southern Coast (Latitude: 6° 1′ 60N, Longitude: 80°
15′ 0E), 3km outside Galle. This luxuriant patch of mangrove forest faces immense pressure due to human activities. Diversity and distribution of mangrove species in relation to salinity levels and species
richness of avifauna were studied from January to June 2009The area was subdivided into three zones based on salinity levels. Zone 1 with recurrent tidal effect had a salinity range of 33-40ppt. Salinity of Zone 2 with moderate influence of tides ranged between 26- 32ppt. Salinity of Zone 3 with least influence of tides ranged between 20-28ppt.

Diversity and distribution of mangrove flora was carried out using quadrat (20x20m) sampling technique. Species richness of birds were determined by carrying out line transects and opportunistic observations. Shannon-Weiner Diversity Index (DI) was calculated to describe floral diversity. Twelve species of true mangroves and six mangrove associates were recorded. Out of eighteen species six were known to be introduced to the wetland. Species richness of Zone 1, 2 and 3 were seven (No. of plots sampled; n=7), six (n=3) and five (n=4) respectively. Increased species richness of Zone 1 is due to introduced species of true mangroves: Rhizophora mucronata, Ceriops tagal and Aegiceras corniculatum

Highest diversity and evenness were recorded from Zone 3 (DI=0.42, J=0.78) and lowest diversity was
recorded in Zone 1 (DI=0.23, J=0.46). Dominant species in Zone 1 were Rhizophora apiculata, Excoecarica agallocha and Clerodendrone inerme. Zone 2 (DI=0.33, J=0.46) was dominated by Rhizophora apiculata and Acanthus illicifolius. True mangrove species Sonneratia caseolaris, Avicennia
officinalis, Heritiera littoralis, Luminitzera racemosa and mangrove associate Cerbera manghas
recorded opportunistically in Zone 2. Acanthus illicifolius was exclusive to Zone 2.

Avifauna consisted of 35 species, of which, 20 were wetland species. There were nine species of migratory birds including one scarce winter visitor- Malayan Night Heron, indicating that Attaragoda wetland is an important destination for migratory birds. Immediate steps should be taken to assure degradation of this wetland habitat by human interventions.

B. Jayasekara1, I.R. Wedage2 and P. N. Dayawansa2
1Department of Forestry and Environmental Sciences, University of Sri Jayewardenepura,
Sri Lanka 2Department of Zoology, University of Colombo, Sri Lanka

Diversity of medicinal plants in the Mihinthale sanctuary

A. Herath1, C. Karunanayake1 and S. Wijesundara2

Sri Lanka contains an enormous biodiversity of medicinal plants. Flora of Sri Lanka reports that there
are 3368 angiosperms in Sri Lanka, out of which 20% are medicinal. There is a growing demand for medicinal plants in primary health care. However, the local supply of medicinal plants can not meet the
demand. About 80% of the locally supplied medicinal plants are collected from the wild. This has lead
to unscrupulous collection and destructive harvesting. Therefore, the present study focused on identifying and documenting the diversity of medicinal plants in the Mihintale sanctuary.

Since medicinal plants may be trees, shrubs, or herbs complimentary sampling techniques were used in
sampling. Quadrate sizes for each plant category was chosen according to the method described by Sutherland. Therefore 20x20m, 5x5m and 2x2m quadrates were located randomly for trees shrubs and
herbs respectively. Data on floristic composition, plant density, basal area and dominance were collected
according to the method described by Crutis and McIntosh. The DBH values of the entire data set were
used for cluster analysis (SAS 6.12). Floristic diversity and richness were analyzed using Biodiversity
professional 2.0 software package. The Basal area, Relative density and Importance Value Index (IVI)
were analyzed using SAS 6.12.

One hundred and fifty nine medicinal plant species, which belong to 111 genera and 54 families, were
encountered in the study area. Of the medicinal plant species, 48 were trees, 33 were shrubs, 42 were
herbs and 32 were vines. The dendogram between cluster sums of squares showed three distinct vegetation communities: near tank vegetation, relatively undisturbed areas and disturbed areas. Munronia pinnata (Bin kohomba) an endangered species was observed only in the relatively undisturbed community while Salacia reticulata (Kothala himbutu) a threatened species and Vernonia zeylanica (Pupula) an endemic species were observed in all three communities. The species richness of medicinal plants varied from 105 to 55 species per community, the highest being in the near tank vegetation and the lowest in the relatively undisturbed community. Shannon diversity Index (H) ranged from 3.47 to 3.08, Simpsons diversity (D) from 0.073 to 0.051 and Margalef’s diversity index (Dmg) from 12.52 to 8.09. Near tank vegetation ranked first in medicinal plant diversity (H=3.47, D=0.05, Dmg=12.52) followed by, disturbed (H=3.19, D=0.073, Dmg=10.6) and relatively undisturbed (H=3.08, D=0.072, Dmg=5.20) vegetation respectively. Relative densities of medicinal plants of the three communities differ significantly (p=0.035). The total sample area contained 289 medicinal trees with stems >10cm DBH. The diameter size distribution of individuals enumerated showed that 64% of them were below 30cm diameter.

Importance value Index (IVI) of woody individuals of the identified three clusters varied from 115 to 0.69. In disturbed vegetation and relatively undisturbed vegetation one species Drypetes sepiaria showed
a significant dominance over other species. Contrastingly, in near tank vegetation nearly seven species
showed high IVI values. The disturbed site showed the highest pioneer and secondary plant species
while the highest primary species number was recorded in the relatively undisturbed communityIn
conclusion, medicinal plant diversity is very high in Mihintale sanctuary. Therefore, immediate action
should be taken for conservation. Furthermore, integration of medicinal plants into farming system is
advisable to derive economic benefits to the local community as well to minimize over exploitation.

A. Herath1, C. Karunanayake1 and S. Wijesundara2
1Department of Biologcal Science, Faculty of Applied Sciences, Rajarata University of Sri Lanka
2Department of Royal Botanic Gardens, Peradeniya, Sri Lanka.

Herpetofaunal diversity and distribution in Kalugala proposed forest reserve in Sri Lanka

W.M.S. Botejue and J. Wattewidanage

This study reports species richness, abundance and diversity of herpetofauna in the Kalugala Proposed
Forest Reserve (KPFR). KPFR is a primary lowland tropical rain forest, surrounded by secondary and disturbed vegetation due to human activities like cultivation, logging and collecting firewood. Herpetofaunal communities of these different habitats (closed forest, ecotone, home gardens and cultivations) were assessed using visual encounter surveys, transects, quadrates and pitfall traps, and
distribution patterns were compared. A total of 24 amphibian species (~63% endemic and ~33%threatened) and 53 reptile species (~38% endemic and ~30% threatened) were recorded. Herpetofaunal
Diversity of KPFR (Shannon Wiener Index, H= 1.668) is considerably high. Overall 742 individual amphibians were recorded and Fejervarya limnocharis was the most abundant while Ramanella
variegata, Philautus abundus, P. cavirostris, P. reticulatus and P. stictomerus show the least abundance.
In total 1032 individual reptiles were recorded and Hypnale hypnale showed the highest abundance while Ahaetulla pulverulenta, Balanophis ceylonensis, Geckoella triedrus, Ramphotyphlops sp., Typhlops
sp. and Rhinophis sp. showed the least. Reptilian distribution patterns are similar to the amphibian
distribution patterns, with the highest diversity being in the closed forest and the lowest diversity in
cultivations as expected. We did not observe an affect of ecotone (edge effect) in amphibian and reptile
diversity except for ecotone and cultivations for reptiles (Mann-Whitney U-test: Z = 2.01, P =0.044).
Adverse human activities especially illegal encroachment in forest for agriculture practices, logging and garbage dumps of the Kalugala Monastery which located inside the forest are major growing threat
to the local biodiversity in KPFR.

W.M.S. Botejue and J. Wattewidanage
1Taprobanica Nature Conservation Society, Sri Lanka
2Department of Zoology, Open University of Sri Lanka.

How do Sri Lankan shrub frogs Philautus popularis spend their night time: Field observations from Bolgoda wetland complex

H.G.S.K. Dayananda and D.D. Wickramasinghe

Sri Lanka is an amphibian hot spot providing home for 109 species. Nevertheless, studies on ecology and biology of amphibians of Sri Lanka are scarce and behaviour of frogs has drawn even less attention. Philautus popularis (Ranidae, Rhacophorinae; Manamendra-Arachchi & Pethiyagoda, 2005) is an endemic shrub frog which occurs in the low country wet zone. This study attempts to report behaiourl
spectrum of P. popularis in an undisturbed wetland in an urban area. Study site comprised of two locations in Bolgoda south lake wetland complex (790 52’ – 790 59’ north longitude and 060 42’ – 060
51’ east latitude). 

This study was carried out for one months starting from mid June 2009 from 1800 hrs onwards. On each study date, a random path was chosen to walk till a frog was found. The observations were made according to focal animal sampling method, by the naked eye. When an animal was found the total behavioural pattern was studied carefully from a point 1 m away from the frog. Times spent on different
behavioural activities were noted. A total of 64617 seconds (nearly 18 hours) were spent on different
behavioural activities. 

Twenty nine individuals (26 males and 3 females) were studied and seven behavioural events were encountered: acoustic, locomotion, resting (No movements), foraging, agonistic, cleaning and sexual behaviour. Time taken for each behaviour was compiled taking both sexes into consideration. The most
abundant behaviour event was resting without any movement (45% of the total time) but sometimes
they showed feeding in between. When activities are considered, they were found spending more time
for calling (27.1%, males only) and sexual behavior including amplexus (25%). Interestingly, agonistic
behaviour was shown by males and time taken was 2.1% of total. Walking, cleaning, jumping and climbing took a negligible proportion of the total time and were less than 0.2 percent. Calling was observed from 1800-2300 and they were silent from 0130-0530 and then started acoustic signals again.
Perch height of males varied from 40-160 cm from the ground and the highest point was reached around
midnight. Females were always near the ground (5-15cm). Males are territorial and it is likely that their
home range is within a 5m radius.

This shrub frog used minimum time to climbing locomotion pattern and then jumping. The most abundant locomotion pattern was walking, spent 59.6% from the total time for locomotion to the walking. 3 Different perched postures were recorded and climbing position was recorded. Perched height and time has significant relationship respect to both study sites. There is no any preferred plant species for Philautus popularis. They spent 1380 seconds on agonistic behaviour, 2% of the total behavioural observation time. They spent time of 16,200 seconds in amplexing. They hide under leaf litter during
day time.

H.G.S.K. Dayananda and D.D. Wickramasinghe
Department of Zoology, University of Colombo, Sri Lanka.

Distribution and population parameters of selected tree species in Gilimale and Kithulgala Forest Reserve

S. S. Ranathunga and B.M.P Singhakumara

Field surveys have not been carried out in Sri Lanka to gather the population data on critically endangered tree species in their habitats. The population data on the critically endangered tree species are important to understand the present status of the population. In this study, the population data of seven critically endangered tree species were gathered.

Habitat distribution and some population parameters such as stand tables, plant community composition and structure were studied for seven Critically Endangered (CR) tree species found in the Kitulgala and Gilimale Forest Reserves, tropical lowland rainforests in the southwest part of the country. The selected species are Stemonoporus gracilis, S. petiolaris, and Balanocarpus kithulgallensis in Kitulgala and Stemonoporus gilimalensis, S. lancifolius, S. scalarinervis, and Memecylon macrocapum in Gilimale. Balanocarpus and Stemonoporus an endemic genus belong to the family Dipterocarpaceae and
Memecylon macrocapum belongs to the Melastomataceae.

Sampling of vegetation has been carried out in specific habitats for each selected Critically Endangered species. Suitable plots were identified by a reconnaissance survey and 100×5 m plots were demarcated. All the plants below 1 m of height were counted as seedlings; all the plants less than 2 cm of dbh and over 1 m of height were counted as saplings. DBH and heights of trees over 2 cm dbh were measured.

Survey data of the selected tree species are used to calculate the Important Value Index (IVI). Profile
diagrams were prepared for each tree species to show the vertical distribution in their habitats. Distribution maps of these species were prepared using digital data. Sample plots are located in 1: 10,000 digitized maps prepared by the Survey Department, Sri Lanka.

All species show patchy distribution and these patches are found in different parts of the forest topography. Stemonoporus gracilis, S. petiolaris, S. gilimalensis, S. lancifolius and S. scalarinervis show positive stand tables with reverse “J” distribution curves. This indicates that these populations in their habitats are healthy. Balanocarpus kithulgallensis and Memecylon macrocapum are not showing this type of curves, and more sampling has to be carried out to investigate the population structure of these two species.

All these species could be conserved by protecting their natural habitats (in-situ conservation) and only a two species (Balanocarpus kithulgallensis and Memecylon macrocapum) might need both in-situ and ex-situ conservation strategies.

S. S. Ranathunga and B.M.P Singhakumara
Department of Forestry and Environmental Science, University of Sri Jayewardenepura, Sri Lanka.

Utilization of treated tannery waste water using HRTS (High Rate Transpiration System)

S. Krishnamoorthi and G. Kandasamy

The major objective of this paper is given to soil and ground water quality improvement by utilizing the high transpiration pull property of specific plants. It acts as a catalyst to improve the water management and also effluent is getting treated in a eco friendly manner. We utilized the tannery effluent for the High Rate Transpiration System (HRTS). The treated tannery effluent is distributed in the designed plants of ridges and Furrows. And three design layouts were developed in the research activity for the plantation to get Maximum benefits depends upon the load and the nature of effluent.

Moreover, implemented system results were collected and analyzed for the impact of system on the environment. The effluent loading capacity to the designed plants were calculated and summarized.

The advantages of the HRTS are 1) No separate processing is required for effluent 2) Effluent Solids will be taken as nutrient for the plants growth 3) Water in the effluent will be penetrated under the beneath of earth and improve the ground water quality as well as quantity 4) HRTS process is ecofriendly.

S. Krishnamoorthi and G. Kandasamy

Environmental Research Center, Sri Ramanathan Engineering College, Erode, India

Efficient removal of nitrogen/phosphorus by Bio-Geo Filter ditches consisting of laterite

G.S.M Fonseka1, N.P.M Rajaguru2, K.C.J Jayasekara2, B.C Liyanage2 and S.S. Iqbal2

In order to develop low-cost energy saving ways to treat wastewater in combination with resource recycling, a plant bed filter ditch in which terrestrial and aquatic plants are used to remove nitrogen (N) and phosphorus (P) from domestic wastewater specially from the septic tank effluents. Discharging waste water into inland surface waters leads to contamination of water bodies is becoming a serious problem in Sri Lanka. Though there are several treatment methodologies adopted to treat wastewater, a low cost system with less maintenance is very much needed that suits small waste capacities and for domestic installation, so as to prevent release of nutrients to the natural ecosystem. Therefore this study focuses on introducing an ideal treatment system using a combination of bio and geo materials namely Geo Filter (BGF) ditches.

 A pilot scale Bio-Geo Filter ditches has been established at the Open University premises to demonstrate the potential for treatment of domestic wastewater using geo materials and plants. Selected bed filter materials and useful terrestrial plant species such as African merigold, canas, papyrus and reeds were employed for nutrient removal. This pilot-scale BGF containing laterite (kabook) stones with its rich composition of iron and aluminium, has been achieved nearly 100% removal of phosphorus.

The BGF shows the excellent pollutant removal efficiencies for NH4 +, NO3-, and NO2 –. Though the removal efficiency of NH4 + is 90%, while the removal of NO3 – and NO2- is around 100%. Ditches with papyrus and reed help to control pH before discharge. Reduction of turbidity and COD is also more than 90%. The BGF significantly removes TDS, conductivity and salinity. The plant species, which provides economic and aesthetically appealing aspects, will engage to produce renewable energy in further step of this study.

[This project was funded by the Asian Development Bank, Distance Education Modernization Project]

G.S.M Fonseka1, N.P.M Rajaguru2, K.C.J Jayasekara2, B.C Liyanage2 and S.S. Iqbal2

1Department of Chemistry, University of Colombo, Sri Lanka 2Department of Civil Engineering, Open University of Sri Lanka.

A Multi agent system for environmental friendly agriculture

R. Rupasinghe, A. Ranatunga, S. Rathnayake, A. Sajagahan and A. Karunananda

Environmental sustainability has become an important topic nowadays due to various adverse effects of natural systems which has caused the mankind to suffer in multi faceted difficulties. Achieving the environmental sustainability is not an individual effort but a collective effort of all the stake holders of a natural system. Therefore mankind should be able to work in harmony with natural processes in utilizing the environment without harming the sustainability.

Agriculture is a direct encounter of humans with the natural environment. Here, the challenge is to reap the maximum possible harvest in the most efficient manner while keeping up with the environmental sustainability. In addressing this issue we propose to incorporate modern agent technology for controlling an agricultural environment. Since we need a controlled environment we decided to select hydroponics, the technology of growing plants on a nutrient solution that supply all nutrient elements needed for optimum plant growth, in a greenhouse environment. We have built an adaptable hydroponics system with high level of autonomy with the help of a multi agent system. In doing so, we have combined embedded computer technology with the state of the art artificial intelligence. The system has a higher capacity of autonomous decision making in a dynamic environment. Decisions about activities to be performed by the actuators (dosing system, water control system etc.) were generated as an emergent property of interacting autonomous software components. Each of these software components represent a particular environmental parameter (nutrient level, pH level, temperature etc.) that is subjected to change dynamically. Each of these autonomous software components contains limited logical capabilities for interacting with nearby components in case of a change of the interested parameter. Therefore the decision will be emerge as a result of the interactions among individual software components with limited rationality. The advantage of this approach is that it enables the hydroponics system to become proactive to the environmental changes rather than being just a reactive entity.

The system has been evaluated using a domestic hydroponics environment. Firstly, we changed key parameters of the nutrient solution in an artificial manner to test how the system would react to those changes. For example, in the first scenario we reduce the water level and switch on the system. System  was able to identify that and pumped the water up to the required level. Similar tests were conducted to ensure component testing. So we reduce the light, change EC / pH, change nutrient level. Also the system was evaluated through a comparative approach with the traditional agriculture. Five farmerswere utilized to obtain data about 6 six parameters for a period of 3 months. The test results showed a considerable improvement over the traditional agricultural practices. Therefore this research has shown that we could achieve a better harmony and sustainability with the natural environment by using the multi agent technology for controlling an agricultural environment.

R. Rupasinghe, A. Ranatunga, S. Rathnayake, A. Sajagahan and A. Karunananda

Faculty of Information Technology, University of Moratuwa, Sri Lanka.