Latest Research on Evergreen Forest : April 21

[1] Transmission of Phytophthora ramorum in Mixed-Evergreen Forest in California


During 2001 to 2003, the transmission biology of Phytophthora ramorum, the causal agent of sudden oak death, was studied in mixedevergreen forest, a common forest type in northern, coastal California. Investigation of the sources of spore production focused on coast live oak (Quercus agrifolia) and bay laurel (Umbellularia californica), dominant hosts that comprised 39.7 and 46.2% of the individuals at the study site, respectively. All tests for inoculum production from the surface of infected coast live oak bark or exudates from cankers were negative. In contrast, sporangia and chlamydospores were produced on the surface of infected bay laurel leaves. Mean number of zoospores produced from infected bay laurel leaves under natural field conditions during rainstorms was 1,173.0 ± SE 301.48, and ranged as high as 5,200 spores/leaf. P. ramorum was recovered from rainwater, soil, litter, and streamwater during the mid- to late rainy season in all 3 years of the study. P. ramorum was not recovered from sporadic summer rains or soil and litter during the hot, dry summer months. Concentrations of inoculum in rainwater varied significantly from year to year and increased as the rainy season progressed for the two complete seasons that were studied. Potential dispersal distances were investigated for rainwater, soil, and streamwater. In rainwater, inoculum moved 5 and 10 m from the inoculum source. For soil, transmission of inoculum was demonstrated from infested soil to bay laurel green leaf litter, and from bay laurel green leaf litter to aerial leaves of bay laurel seedlings. One-third to one-half of the hikers tested at the study site during the rainy season also were carrying infested soil on their shoes. In streamwater, P. ramorum was recovered from an unforested site in pasture ≈ 1 km downstream of forest with inoculum sources. In total, these studies provide details on the production and spread of P. ramorum inoculum in mixed-evergreen forest to aid forecasting and managing disease transmission of this environmentally destructive pathogen.

 

[2] Satellite-based modeling of gross primary production in a seasonally moist tropical evergreen forest

A CO2 eddy flux tower study has recently reported that an old-growth stand of seasonally moist tropical evergreen forest in Santarém, Brazil, maintained high gross primary production (GPP) during the dry seasons [Saleska, S. R., Miller, S. D., Matross, D. M., Goulden, M. L., Wofsy, S. C., da Rocha, H. R., de Camargo, P. B., Crill, P., Daube, B. C., de Freitas, H. C., Hutyra, L., Keller, M., Kirchhoff, V., Menton, M., Munger, J. W., Pyle, E. H., Rice, A. H., & Silva, H. (2003). Carbon in amazon forests: Unexpected seasonal fluxes and disturbance-induced losses. Science302, 1554–1557]. It was proposed that seasonally moist tropical evergreen forests have evolved two adaptive mechanisms in an environment with strong seasonal variations of light and water: deep roots system for access to water in deep soils and leaf phenology for access to light. Identifying tropical forests with these adaptive mechanisms could substantially improve our capacity of modeling the seasonal dynamics of carbon and water fluxes in the tropical zone. In this paper, we have analyzed multi-year satellite images from the VEGETATION (VGT) sensor onboard the SPOT-4 satellite (4/1998–12/2002) and the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Terra satellite (2000–2003).


[3] The albedo of a tropical evergreen forest

The diurnal variation of the average albedo, during 1970, over a tropical dry evergreen forest and a nearby clearing was investigated. The study is based on a most comprehensive set of solar radiation data in Southeast Asia. A strong dependence of the albedo on the zenith angle is evident. This dependence is subdued during cloudy days. The average midday albedo for the winter monsoon season is 10.6 for the forest and 13.4 for the clearing; for the summer monsoon it is 12.0 for the forest and 14.6 for the clearing. Generally, results show great uniformity. The largest standard deviations are 0.05 with a more representative value in the range 0.01–0.02.

 

[4] Diversity and Ecology of Macrofungi in Rangamati of Chittagong Hill Tracts under Tropical Evergreen and Semi-Evergreen Forest of Bangladesh

A detailed survey was made in Rangamati district of Chittagong hill tracts from July to October, 2016 to collect and record the morphological and ecological variability of macrofungi fruiting body. Collected macrofungi were washed with water and dried by electric air flow drier. Permanent glass slides were made from rehydrated basidiocarp for microscopic characterization. Morphology of basidiocarp and characteristics of basidiospore were recorded. Ecological features of the collected macrofungi and the collection sites such as location of collection, host, habit, frequency of occurrence, density and environmental temperature, soil type and soil moisture conditions were also recorded during collection time. A total of 66 samples of macrofungi were collected, recorded, photographed and preserved. Twenty species of macrofungi were identified under 17 genera and 15 families. The highest frequency of occurrence (44.44%) was recorded for Xylaria polymorpha. The highest density was found for Xylaria polymorpha also (55.56%) followed by Coprinus disseminatus (52.78%), Auricularia cornea (38.89%), Xylaria hypoxylon (27.78%) and Clavulina coralloides (16.67%). This is the first detail reports on macrofungi collected from Rangamati Hill Tracts forest of Bangladesh. Collected specimens were deposited to the SAU Herbarium of Macrofungi (SHMF).

 

[5] Impact of Ecotourism on the Environment, Society and Culture of Ratargul Swamp Forest in Sylhet, Bangladesh

Aims: The aim of the paper is to know the type of ecotourism going on Ratargul swamp forest and its impact on the environment, society and culture of the area.

Study Design: This paper is a qualitative study and empirical research. It focuses on the change in the local environment and local people’s life due to ecotourism. For this purpose, interviews have been collected from people as a representative of the study population.

Place and Duration of Study: Ratargul Swamp Forest on Goainghat upazilla under Sylhet District, between August and September 2014.

Methodology: The respondent sample size was 100. Data has been collected from the local people by using structured observation, semi-structured interview and case study which were selected by stratified random sampling on the basis of education and profession.

Results: Observed evidence shows that foremost influence of ecotourism fall on economic aspect and environmental knowledge. Income level of 80% people has been increased after establishing ecotourism and 57% people have now changed their traditional occupation. Unplanned and unmanaged tourism may disrupt the life cycles of many aquatic biota that thrive there. Many tourists carry bottled water or juice, potato chips and other food stuffs while travelling the area and finally discard the resulting waste recklessly in the forest despite the use of warning signs by the forest department and other concerned authorities. More use of engine boats to carry the tourists in an undefined and multiple ways inside and around the forest also creating noise and polluting air and water there which are disturbing the life styles of the habitats inside the swamp forest to be settled like the previous stable and natural environment.

Conclusion: To save this swamp environment, government and forest department should make and implement some management policies which should be maintained strictly considering the opinion of the local people.

 

Reference

[1] Davidson, J.M., Wickland, A.C., Patterson, H.A., Falk, K.R. and Rizzo, D.M., 2005. Transmission of Phytophthora ramorum in mixed-evergreen forest in California. Phytopathology95(5), pp.587-596.

[2]  Xiao, X., Zhang, Q., Saleska, S., Hutyra, L., De Camargo, P., Wofsy, S., Frolking, S., Boles, S., Keller, M. and Moore III, B., 2005. Satellite-based modeling of gross primary production in a seasonally moist tropical evergreen forest. Remote Sensing of Environment94(1), pp.105-122.

[3] Pinker, R.T., Thompson, O.E. and Eck, T.F., 1980. The albedo of a tropical evergreen forest. Quarterly Journal of the Royal Meteorological Society106(449), pp.551-558.

[4] Marzana, A., Aminuzzaman, F.M., Chowdhury, M.S.M., Mohsin, S.M. and Das, K., 2018. Diversity and ecology of macrofungi in Rangamati of Chittagong Hill Tracts under tropical evergreen and semi-evergreen forest of Bangladesh. Advances in Research, pp.1-17.

[5] Jahan, K.M. and Akhter, H., 2018. Impact of ecotourism on the environment, society and culture of ratargul swamp forest in sylhet, Bangladesh. Asian Journal of Environment & Ecology, pp.1-8.

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