G. Weerakoon1, S. Somaratne2, P.A. Wolseley3 and S.C. Wijeyaratne1
1Department of Botany, University of Sri Jayewardenepura, Sri Lanka
2Department of Botany, The Open University of Sri Lanka
3Department of Botany, The Natural History Museum, United Kingdom
Lichens have been widely considered as bioindicators of forest health and ecological continuity as well as atmospheric pollution. The use of lichens as bioindicators in tropical zones has been hampered by the lack of taxonomic and ecological knowledge. The purpose of the study was to assess the variation of lichen diversity in different forest management regimes under different environmental conditions on the basis that their potential uses as bioindicators of environmental alterations in different habitats in the Knuckles mountain range. The sampling sites were chosen to include pristine forest of montane and sub-montane and six different disturb vegetation types. Lichen species, their frequency and cover values were recorded together with environmental parameters in 20 sites of 100 m2 plots. Ten trees were sampled randomly in each plot. The collected data were analyzed to assess the relationship between lichen diversity and environmental conditions in different forest management regimes using one-way analysis variance, least significant difference- LSD (mean comparison) and Regression tree analysis.
There were 192 lichen species recorded from the natural vegetations, where as 148 lichen species present in the disturbed vegetation types. The results of the study have shown that there is a considerable variation in the lichen diversity along different vegetation types and their degree of disturbance. The statistical analysis revealed a significant variation in lichen diversity between the disturbed and undisturbed vegetation in the area (F = 6.213, df = 1; p ≤ 0.05). Similarly, lichen diversity in different vegetation types also indicated a remarkable variation (F =3.21, df = 7; p ≤ 0.05). The results obtained from regression tree analysis indicated that there were three important variables that determined the lichen diversity of the study area; type of vegetation, altitude and association with other cryptogamic communities.
There are distinct lichen communities associated with tree boles in disturbed forests including weedy taxa and low diversity with few forest lichen species. The analysis of epiphytic lichen diversity showed significant difference in the natural vegetation and disturbed vegetation.
This may be due to the heterogeneity of microclimatic conditions and specialist lichen communities associated with pristine tropical forests. Thus, there is utmost importance to identify lichen communities that can be use as indicators of reflecting forest health for the purpose of sustainable management.
S. Rameshkumar, K. Manivannan, C.T. Sathappan and J. Padmanaban
Annamalai University, India
Quantum jump of increase in the awareness about global warming and environmental pollution made the mind set of industries, institutions, corporate and even common man to think about finding a solution to it. Establishment of ornamental gardens and green belt development in the surroundings and waste lands is becoming the best option to curtail pollution problems and it has almost been considered as mandate in urban areas. Increased green belt development and gardening activities help the industries and corporate to manage their carbon credit and in turn helps in reducing climate change. In these green belts and corporate landscapes and even in botanical gardens many alien species are used in larger volumes.
In a survey conducted in nursery pockets and landscape industries of south India evinced the status of alien species that more than 60 per cent of the ornamental species are foreign in origin and few species are Invasive in nature. More than 50 per cent of the landscape architects opted for foreign ornamental plants to be incorporated in their present and future projects and opined it is inevitable to avoid the invasive alien ornamentals as they have preference among the clients. Though many of these plants are well accommodative and have ornamental value, there is a chance for certain highly invasive alien species to become threat for the eradication native species in the locale and may become serious weed as evident from Lantana Sp. and water hyacinth which were introduced as ornamental plants and now being a threat as major weeds in Indian sub continent. Hence it becomes necessary to have check measures to evaluate the invasiveness of the alien species when it is introduced as an ornamental plant.
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