Abstract:Rapid urbanization has changed the structure and function of natural ecosystems, especially floodplain ecosystems in SE Asia. The ecological structure of vegetation stands and the usefulness of satellite images was investigated to characterize a disturbed tropical urban forest located in the Chao Phraya River lower floodplain, Thailand. Nine sample plots were established on the Bang Kachao Peninsula (BKP) within 4 tropical forest types in an urban area: rehabilitation forest, home-garden agroforestry, mangrove and park. The tree habitats were beach forest, swamp forest, moist evergreen forest, dry evergreen forest, mangrove forest and abandoned orchard or home-garden. Normalized difference vegetation index (NDVI) values obtained from Landsat 7 satellite images were correlated with plant structure from field surveys. NDVI had the highest relationship with stand factors for number of families, number of species, Shannon-Weiner index and total basal area. Linear regression predicted well the correlation between NDVI and stand factors for families and basal area. NDVI trends reflected urban tropical forest typing and biodiversity, being high in rehabilitation and mangrove forests, moderate in home-gardens and low in parks. We suggest that the application of NDVI for assessments can be useful for future planning, monitoring and management of the BKP and hence may contribute for increasing biodiversity and complexity of these urban forests.

Abstract:Rapid urbanization has changed the structure and function of natural ecosystems, 15especially the floodplain ecosystems in SE Asia. This paper describes the ecological structure of

High-value native timber species are being promoted in reforestation in Southeast Asia. However, slow growth during early establishment, coupled with poor soil fertility, poses challenges for promoting tree planting programs. Field trials were undertaken on agroforestry land in Thailand to examine the efficacy of reforestation treatments. The first trial examined the effect of applying microorganisms and fertiliser on directly seeded Acacia mangium Willdenow, Dalbergia cochinchinensis Pierre and Xylia xylocarpa (Roxburgh) Theobald. After 20 months, a mixed inoculum of arbuscular mycorrhizal and ectomycorrhizal fungi improved survival and basal diameter of D. cochinchinensis by 15 and 43%, respectively. The co-inoculation of arbuscular mycorrhizal fungi and N 2 -fixing bacteria improved survival by 17%. The second trial investigated the effects of fertiliser and a water retention polymer on directly seeded A. mangium, Afzelia xylocarpa (Kurz) Craib, D. cochinchinensis, Eucalyptus camaldulensis Dehnhardt, Sindora cochinchinensis Baillon and X. xylocarpa. Height was improved by 40% at 20 months. Our findings suggest that reforestation is viable, provided that suitable treatments are used. These principles can be applied for reforestation of nutrient-impoverished soils of continental Southeast Asia.