Natural regeneration is an essential component of forest dynamics and the recovery of ecosystem functions. Therefore, understanding regeneration status, and how abiotic and biotic factors affect it, is important for ecological studies. This study discovered different regeneration statuses of tropical forests in response to differences in rainfall in Myanmar, and the environmental and overstory factors that had the most influence on understory regeneration. Study sites were set up in regions with 625 to 2035 mm of annual rainfall, and ecological characteristics were measured. According to the results, natural regeneration increased with rainfall, showing a good regeneration status at all sites. Forests within a range of 1411-2035 mm of annual rainfall had a significantly higher density and species diversity at specific natural regeneration stages than those with 625-1029 mm. Not only abiotic but also overstory structure affected the natural regeneration of forests. However, not all factors influenced natural regeneration status. Overstory size distribution parameters did not show a significant influence on natural regeneration. Average annual rainfall (abiotic), as well as ecosystem complexity, density, species richness, and diversity (overstory), were found to be the most influential factors for the density and diversity of natural regeneration. The results of this study will support silviculture and the management of tropical forests.

Abstract:Plants can undergo external fluctuations in the natural light and dark cycle. The photosynthetic apparatus needs to operate in an appropriate manner to fluctuating environmental factors, especially in light. Yellow-poplar seedlings were exposed to nighttime artificial high-pressure sodium (HPS) lighting to evaluate night light-adaptation strategies for photosynthetic apparatus fitness relative to pigment contents, photosystem II photochemistry, photosynthetic parameters, histochemical analysis of reactive oxygen species, and plant biomass. As a result, seedlings exhibited dynamic changes including the enhancement of accessory pigments, the reduction of photosystem II photochemistry, increased stomatal limitation, downregulation of photosynthesis, and the decreased aboveground and belowground biomass under artificial night lighting. Histochemical analysis with 3,3 -diaminobenzidine (DAB) and nitroblue tetrazolium (NBT) staining indicates the accumulation of in situ superoxide radicals (O 2 − ) and hydrogen peroxide (H 2 O 2 ) in leaves exposed to the lowest level of artificial night lighting compared to control. Moreover, these leaves exposed to artificial night lighting had a lower nighttime respiration rate. These results indicated that HPS lighting during the night may act as a major factor as repressors of the fitness of photosynthesis and growth patterns, via a modification of the photosynthetic light harvesting apparatus.

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The present study was conducted to examine the response of Pterocarpus indicus to elevated ozone by comparing the effects between well-watered and soil drought treatments. The ozone concentration was 200 ppb and the exposure was conducted for a month with wellwatered and soil drought treatments in chamber environmental conditions. Elevated ozoneinduced visible injuries to P. indicus varied among the well-watered environmental conditions, with the appearance of light green chlorosis in the SWO seedlings over time. However, in the SDO seedlings, no difference was visible between drought and drought with ozone treatment. Shriveled leaves were evident because of the water deficiency. Moreover, elevated ozone induced leaf stomata injury and a harsh abaxial surface, whereas drought stress induced less injured stomata because of stomata closing. In addition, the palisade tissues exhibited smaller chloroplasts, damaged thylakoid, increased plastoglobuli, decreased starch grain and thinner cell walls on the upper leaf surface. Thus, the SDO seedlings were less influenced by elevated ozone stress than SWO seedlings due to the reduced ozone absorption which caused by stomata closing to prevent water loss.

Abstract. In this study, the resistance to ozone and characteristics of ozone-induced damage were investigated on the perennial ground cover plant species. Sedum kamtschaticum and Hosta longipes were exposed to 200 μg･kg -1 ozone for 8 hours per day (from 08:00 to 16:00) in the naturally irradiated phytotron. The extent of ozone-induced damage was measured through the analysis of physiological parameters, such as water use efficiency (WUE), chlorophyll content (Chl. a, Chl. b, Chl. a + b, and Chl. a/b ratio), carotenoid contents, and the induction of reactive oxygen species (ROS). Ozone exposure significantly reduced the daytime WUE in both species. The contents of chlorophyll and carotenoid were also decreased and ROS, such as hydrogen peroxide (H 2 O 2 ) and superoxide radical (O 2 -) were accumulated after ozone exposure. The above results of this study suggested that S. kamtschaticum is more resistant to atmospheric ozone than Hosta longipes. Considering its fast responses to ozone, it was also assumed that Hosta longipes can be used as an indicator plant of an increase in atmospheric ozone concentration.

-Humankind has been searching for medicinal materials from various plant sources in an attempt to treat disease. Mistletoe is one indubitable plant source for these materials due to its effectiveness in treating various diseases, but it has almost disappeared from the mountainous areas of Korea due to excessive harvesting. In this study, in order to select host tree species for Korean mistletoe [Viscum album var. coloratum (Kom.) Ohwi] by seed inoculation and to clarify the effect of host specificity among various tree species were conducted for the purpose of gaining basic information for the artificial cultivation of Korean mistletoe. Almost all the seeds of Korean mistletoe germinated in vitro at the temperature of 15℃. Among host trees used in this study, Prunus mume showed the highest parasitic affinity with inoculated Korean mistletoe, compared with any other host plants. However, treatment of hormones could not increase the low survival rate of Korean mistletoe on the host trees.

The ASEAN-Korea Environmental Cooperation (AKECOP) was initiated in 2000 aimed at enhancement capacity of member countries in the ASEAN region in managing their ecosystem and improvement of local livelihood with participating institutions in each ASEAN Member States (AMS). AKECOP researchers implemented regional research dealing with restoration of degraded ecosystems, agroforestry, biodiversity conservation, biomass, and mangrove conservation. In addition, it was also good opportunity for Koreans to understand tropical forest ecosystem and enhance their research capacity through the collaborative research activities. Furthermore, recognition of the importance on the human and institutional capabilities on environmental and forestry issues in AMS, AKECOP provide regular training course, workshops and scholarship program for young generations. AKECOP collaboration was clearly demonstrated in four areas: project management, research and development, information exchange and technology transfer, and human resource development during the last 15 years. The strategic vision calls for AKECOP to allocate more support for the strengthening the capability of all participating AMS to more eff ectively respond to local and national manpower needs in forest restoration. AKECOP is envisaged to evolve and adopt strategies responsive to the changing needs and challenges required for the maintenance of a healthy and sustainably managed forest ecosystem also envisioned in the new Sustainable Development Goals (SDGs).