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Highlights: [•] Tropical swamp forests growing on peatlands are exposed to the risk of forest fires. [•] We compared the fuel mass of peat swamp forests in burnt and unburnt areas. [•] The fuel mass in burnt areas consisted mainly of solid deadwood. [•] The condition of fallen deadwood following a fire differed between forest types. [•] The estimated GHG emission after a forest fire was larger than that during the fire. [ABSTRACT FROM AUTHOR]

Abstract: We estimated the total aboveground tree biomass (TAGB) in an old-growth primary forest and in a regenerating forest that had been selectively logged in 1958, both within the tropical rainforest of the Pasoh Forest Reserve in Peninsular Malaysia. This was achieved by comparing aerial photographs with data obtained previously from destructive sampling in the same area. Aerial photographs were taken above the primary and logged forest plots in 1997. The heights of the canopy-forming trees were estimated in both plots by means of aerial triangulation and were regressed against the diameter at breast height (DBH) of the corresponding trees measured during ground surveys. The resulting allometric relationship between tree height and DBH let us estimate TAGB: in the primary forest, TAGB was 310Mgha-1, which was ca. 10–12% smaller than the value estimated by means of destructive sampling conducted in the 1970s. The estimated TAGB of the logged forest was 274Mgha-1, which was significantly smaller than that of the primary forest (P < 0.05). We also measured canopy surface height in a 2.5m grid system. We found that the mean canopy surface height (MCH) in every 20m × 20m subplot (0.04ha) was significantly (P < 0.0001) correlated with TAGB for that subplot. This suggests that the spatial variation of TAGB can be estimated using MCH values obtained from such a grid system, and that biomass levels can potentially be estimated by means of satellite remote sensing on larger scales, even for very dense tropical forests. We also found that digital reflectance values from Landsat Thematic Mapper (TM) images differed significantly between the logged and primary forests, and hypothesize that these differences relate to structural differences in the canopy surface. However, TAGB in both plots was poorly correlated with the Landsat reflectance values, suggesting the necessity of using an active remote-sensing sensor or a laser profiling system that can quantify changes in the forest''s vertical structure or volume to estimate biomass and its variation in dense evergreen forests. [Copyright &y& Elsevier]

Japanese cypress (Chamaecyparis obtusa Endl.) and Japanese cedar (Cryptomeria japonica D. Don) are common species for plantation forestry in Japan. Cypress is conventionally planted on sites of low fertility whereas for cedar high fertility sites are used. Objectives of this study were to compare the productivities of cypress and cedar plantations grown on adjacent sites where common properties of soils, such as pH values and C and N contents, were similar, and to relate the N cycling at their site with productivities. The stem diameter of trees, aboveground litter production and fine root biomass were measured as indices of forest productivity. Parameters of N cycling included pools of total N and mineral N (ammonium + nitrate), annual N leaching, and potentially mineralizable N. The radial stem increment of the two tree species was similar. However, cedar site had higher total basal area and annual basal increment than cypress site reflecting higher tree density on the cedar site. Aboveground litter, fine root biomass, soil organic matter, and N turnover were higher on the cedar site than on the cypress site. However, litter production and fine root biomass per unit basal area was greater at the cypress site. Phenological pattern of stem growth and periodical litter production were similar for both species during the study period (1992–2000), but showed distinct annual variations caused by the fluctuation in the ambient temperature and precipitation. Mineral N content and the N mineralization potential were greater on the cedar site, indicating greater N availability and higher total tree productivity at the cedar site than those at the cypress site. When provided with more space in the canopy to expand more needles and in the soil to develop more fine roots to exploit sufficient resources, the individual cypress trees have the potential to grow faster. On fertile site and at lower tree density, thicker logs of cypress might be yielded. [Copyright &y& Elsevier]