Vol. 3 No. 1 (2013)

Mella (Olax zeylanica) Leaves as an Eco-friendly Repellent for Storage Insect Pest Management

2013-01-01T00:00:00Z

Mella (Olax zeylanica) Leaves as an Eco-friendly Repellent for Storage Insect Pest Management Fernando, H. S. D.; Karunaratne, M. M. S. C.

Composition of Mix Species Foraging Flocks of Birds in Riverstan of Montane Region, Sri Lanka

2013-01-01T00:00:00Z

Composition of Mix Species Foraging Flocks of Birds in Riverstan of Montane Region, Sri Lanka Shermila, W.G.D.D.M.; Wikramasinghe, S. Montane zone mixed-species bird flock system is distinct from that of low-land wet zone of Sri Lanka, although some species are present in both systems. The present study identified the mixed species flocks of birds in Riverstan at Knuckles Region, Sri Lanka. Monthly transect counts and opportunistic observations were made between January and May, 2012. A total of 78 flocks and 27 bird species were encountered at Riverstan during the study period. The flock size varied between 2 to 13 species and 4 to 58 individuals. The mean number of species per flock was 6.03 ± 2.25 and the mean number of individuals in a flock was 18.41±9.87. The flock size was positively correlated with the number of species present (r = 0.756, P <0.05). Grey-headed Canary Flycatcher was the most abundant species (mean 2.68±1.02 birds per flocks) while Sri Lanka White-eye was the most frequent species (mean 5.69±3.92 birds per flocks). Grey-headed Canary Flycatcher and Sri Lanka Scimitar-babbler were the nuclear species in Riverstan. The leading species were Sri Lanka white-eye and Sri Lanka Yellow-eared Bulbul. Different bird species used different heights within flocks.

Palaeoclimate change during Glacial Periods: Evidence from Sri Lanka

2013-01-01T00:00:00Z

Palaeoclimate change during Glacial Periods: Evidence from Sri Lanka Katupotha, J. In the Earth’s history, there were five major glaciations, namely, Huronian (2,300 Ma), Cryogenianor Sturtian-Varangian(850-635 Ma), Andean-Saharan (460-430 Ma, Karoo (360-260 Ma) and the Quaternary (2.58 Ma to Present) that occurred between 2,300 Ma and 0.0114 Ma. It is revealed that Gondwanaland emerged between the Huronian glaciation (2300-2100 Ma) in the Paleoproterozoic Era and the Andean-Saharan glaciation (460-420 Ma) in the Early Paleozoic Era. During this time, most continental land masses were clustered in the southern hemisphere, and Sri Lanka was part of the Gondwanaland landmass comprising present day Africa, Madagascar, India and Antarctica. Within the Ordovician (485.4-445.2Ma) to Permian Periods (299.0-254.2 Ma) there were signs of the breaking up of Gondwanaland resulting in the severing of India and Sri Lanka together and subsequently Sri Lanka from India. By end of the Permian Period (260 Ma) Karoo Glaciation had ended and the present Mannar Basin developed within a deep canyon (about 4-7 km deep) on the Precambrian basement. Although the island of Sri Lanka presently lies in the Indian Ocean between 5º 52´N-9º 54´N and 79º 30´E-81º 55´E, to the southwest of Bay of Bengal and southeast of Arabian Sea, it was positioned within 67ºS-65ºS and 34ºE-43ºE during the Lower and Middle Jurassic Era (201.3-166.1 Ma). Huge rocky blocks (erratic boulders) have been transported to different places by continental ice sheets due to climatic changes in the Permian, Triassic and Jurassic Periods, but erratic pebbles (2 to 8 cm or more in size) and streams fed deposits have been transported by glacifluvial processes. These glaciofluvial processes occurred on four occasions during the Jurassic Period and Eocene, Miocene and Pliocene Epochs on Sri Lankan landmass, which fallowed the climatic changes and sea level fluctuations that broke up the sedimentary beds, initiating establishment of the present topography and structural configuration. As a result, the earlier sedimentary deposits were obliterated from greater part of Sri Lanka. During the Quaternary Period the erosional rate increased and the resultant erratic boulders along with glaciofluvialdeposits can still be found on “Planated Surfaces”of Sri Lanka.

Effect of Tree Height and Girth on Gum Yield of Acacia senegal L. in Savanna Woodland of Nigeria

2013-01-01T00:00:00Z

Effect of Tree Height and Girth on Gum Yield of Acacia senegal L. in Savanna Woodland of Nigeria Unanaonwi, O.E.; Bada, S.O. Parameters influencing gum yield such as tapping techniques and soil mineral elements had earlier been investigated while there is dearth of information on effect of morphological characteristics on gum yield. This study investigated effects of height and girth on yield of Acacia senegal L. in the natural forests. Three heights and girth classes were purposely selected. Trees which heights and girth fell within those classes were selected randomly and tapped at constant height classes with varying girth classes. Exudates were collected, weighed and recorded according to height and girth class respectively. Descriptive and ANOVA results showed that when total tree height was lower than 2.0 m, gum yield increased as tree girth goes higher from 35 - 54cm (163.6 - 209.7g). Tree girth significantly affected gum yield (p≤0.05) and trees which total heights were lower than 2.0m (maximum of 1.95m) and girth higher than 54cm (maximum of 65cm) produced the highest mean gum yield. Silvicultural practices that could bring about increase in girth such as early pruning and re-spacing which is applicable to plantation trees could also be carried out on the natural forest trees to increase gum yield.