Osamu Kozan

Understanding the impact of fire on termites in degraded tropical peatlands and the mechanisms for their ecological success: current knowledge and research needs

Peatlands have experienced large scale changes due to extensive deforestation for logging, conversion to agro-industrial plantations, and frequent peat fires. The adverse effects of peat fires can lead to long-term impacts on invertebrate biodiversity in the peatland ecosystem. Although the impact of fire on termite diversity in tropical grasslands and savannas has been the focus of increased attention in recent years, little is known about the effects of peat fires on termite assemblages. In this review, we present available information about the impact of human use of peatlands on termite assemblages in the Indo-Malayan region. By synthesizing the currently available studies conducted in temperate and tropical savanna systems, we highlight the need for studies of the relationship between termites and fire-impacted tropical peatlands. We consider the ecological and biological scenarios in fire-impacted peatland that are likely to shape termite assemblages, and we discuss traits of the surviving genera (i.e., Coptotermes, Schedorhinotermes, and Parrhinotermes) that may contribute to their success in the harsh post-fire peatland environment (e.g., colony fusion, colony breeding structure, subsidiary nests, and colony migration). Knowledge of these strategies is crucial for understanding the evolutionary adaptation process of termites. This review also aims to stimulate further research in using termite ecosystem services to restore the fertility of degraded fire-impacted peatlands.

Carbon stocks in tropical evergreen broadleaf forests in Central Highland, Vietnam

SUMMARY This is the first study on carbon stock estimation in the tropical evergreen broadleaf forests in Central Highland, Vietnam. As result of selective logging and shifting cultivation, remaining forests are silviculturally classified to five categories by governmental standard basing on standing volume (V), including very poor forest (V ≤ 10 m3/ha), poor forest (10 < V ≤ 100 m3/ha), medium forest (100 < V ≤ 200 m3/ha), rich (200 < V ≤ 300 m3/ha), and very rich forest (V > 300 m3/ha). Carbon stock of four pools including big trees (diameter at breast height/dbh ≥ 5 cm), short vegetation layer (dbh < 5 cm), necromass, and soil was measured by using 150 plots of 50 m × 50 m each. Soil carbon stock was assessed from soil samples taken to 30 cm depth. The results indicated total carbon stock increased from 75 tons C/ha in very poor forest to 199 tons C/ha in medium forest, and to 255 tons C/ha in very rich forest. Carbon stock in necromass was significant different (ANOVA; F(4,145) = 61.70, p < 0.001) among forest categories (from 4 to 8 tons C/ha). Meanwhile, there were no differences of carbon stock in soil and short vegetation layer among forest categories, which ranged 59–64 tons C/ha and 3–4 tons C/ha, respectively. There was a linear positive relationship between carbon in big trees and that in necromass (R(149) = 0.61, p < 0.01). It is concluded that the degree of human disturbance had significant impacts on carbon sink in the present study forests.

Participatory Management of Desert Rangelands to Improve Food Security and Sustain the Natural Resource Base in Uzbekistan

This chapter presents an analysis of contemporary status of rangelands, vegetation, and land use in Uzbekistan. Constraints to development include the climate and other physical conditions, but the socioeconomic and the policy environment are also barriers to adoption of better land management. The large rural population in remote areas is in subsistence mode, and there is little opportunity to improve household income in the face of the lack of access to grazing lands, lack of secure land tenure, and limited rural financial services. Measures to introduce and implement sustainable land management concepts and practices are outlined.

Aboveground biomass increment and stand dynamics in tropical evergreen broadleaved forest

ABSTRACT Forest ecosystems can modify the atmospheric CO2 through biomass accumulation mostly in tree stems with diameter at breast height (DBH) ≥ 10 cm. Aboveground biomass increment (ΔAGB), and changes in stand AGB, no. stems and basal area (BA) were calculated from mortality, recruitment, and growth data of tree stems in tropical evergreen broadleaved forest, Central Highland Vietnam. Data were derived from ten 1-ha permanent plots established in 2004, where all stems with DBH ≥ 10 cm were tagged, identified to species, and measured for DBH in 2004 and 2012. In an 8-year duration, the increment was 53 ± 10 stems ha–1, 7.8 ± 0.3 m2 ha–1 for BA and 86.0 ± 4.6 Mg ha–1 for AGB. The stem mortality rate was 0.9% year–1 and the stem recruitment rate was 2.2% year–1. Annual ΔAGB was 10.8 Mg ha–1 year–1, equaling to 5.4 Mg C ha–1 year–1. Of which, tree stems of 35–80 cm DBH classes accounted for 65%. The results indicated that the forest is in stage of carbon sequestration. Any disturbances causing death of 35–80 cm DBH tree stems will much reduce carbon sequestration capacity and it will take a long time for AGB to return to pre-disturbance stage.

The effect of remnant forest on insect successional response in tropical fire-impacted peatland: A bi-taxa comparison

Fire has become a common feature in tropical drained peatlands, and it may have detrimental impacts on the overall biodiversity of the forest ecosystem. We investigated the effect of fire on termite and ant assemblages and the importance of remnant forest in restoring species diversity in fire-impacted tropical peat swamp forests. The species loss of both termites and ants was as high as 50% in some fire-impacted peats compared to remnant forests, but in most cases the species richness for termites and ants was statistically equal along the land uses surveyed. However, a pronounced difference in functional group composition of termites was detected. In particular, sites close to remnant forests contained two additional termite feeding groups so that they shared a similar composition structure with remnant forests but were significantly different from sites distant from remnant forests. In general, ants were resilient to fire, and the similarity index showed a high degree of similarity among ant communities in all land uses surveyed. The Shannon diversity index for termites and ants decreased with increasing distance from the remnant forests and level of ecological degradation. Peat vegetation variables and ecological degradation were important in shaping termite and ant communities in the tropical peatlands, but their relative importance was not significant in fire-impacted peats regardless of distance from the remnant forests. This study highlights the importance of remnant forests as a biodiversity repository and natural buffer that can enhance species diversity and recolonization of forest-adapted species.

Classification of crop fields in northeast Thailand based on hydrological characteristics detected by L-band SAR backscatter data

Synthetic aperture radar (SAR) backscatter amplitude image data have proven useful in estimating soil moisture levels and in approximating areas of water inundation over large regions. Based on the pattern of seasonal change in the backscatter coefficient at each image pixel, this study classified a variety of crop fields in Northeast Thailand according to their hydrological characteristics. L-band horizontal-transmit horizontal-receive (HH) polarization images from advanced land observing satellite phased array type L-band synthetic aperture radar (ALOS-PALSAR) at six dates from January to December over the rainy season (May to November) in 2007 were used. Fifteen clusters of pixels were generated using the k-means method, with five variables obtained by taking the difference between the backscatter coefficient for the dry season (January) and the other five dates, effectively removing effects of soil surface roughness. As a result, a detailed spatial distribution of hydrological characteristics that accurately reflected topographical features and hydrological conditions was obtained.

Cost - Benefit Analysis for Agroforestry Systems in Vietnam

Agroforestry has been practiced for a long time in Vietnam. In this study, the cost - benefit was analyzed in four agroforestry systems, which have been widely established in north mountainous provinces with Star Anise ( Illicium verum ) + t ea (IT), bead tree ( Melia azedarach ) + cassava (MC), Acacia hybrid + cassava (AC) and Acacia mangium + maize (AM). A questionnaire was used to obtain information on (1) Inputs , which included costs for seeds/seedlings, fertil izers, pesticides, and labor costs, and (2) Incomes , which included benefits from selling fruits, leaves, corns, and timbers. The results indicated that IT had the highest economic benefit (6,527 US

Altitudinal Changes in Species Diversity and Stand Structure of Tropical Forest , Vietnam

ha - 1 y - 1 ), followed by MC (2,905 US

Ground-based measurements of column-averaged carbon dioxide molar mixing ratios in a peatland fire-prone area of Central Kalimantan, Indonesia

ha - 1 y - 1 ), AC (1,043 US

Visualizing the Spatiotemporal Trends of Thermal Characteristics in a Peatland Plantation Forest in Indonesia: Pilot Test Using Unmanned Aerial Systems (UASs)

ha - 1 y - 1 ), and AM (870 US