The response of decomposition of litter for the dominant tree species in disturbed (pine), rehabilitated (pine and broadleaf mixed) and mature (monsoon evergreen broadleaf) forests in subtropical China to simulated N deposition was studied to address the following hypothesis: (1) litter decomposition is faster in mature forest (high soil N availability) than in rehabilitated/disturbed forests (low soil N availability); (2) litter decomposition is stimulated by N addition in rehabilitated and disturbed forests due to their low soil N availability; (3) N addition has little effect on litter decomposition in mature forest due to its high soil N availability. The litterbag method (a total of 2880 litterbags) and N treatments: Control-no N addition, Low-N: −5 g N m−2 y−1, Medium-N: −10 g N m−2 y−1, and High-N: −15 g N m−2 y−1, were employed to evaluate decomposition. Results indicated that mature forest, which has likely been N saturated due to both long-term high N deposition in the region and the age of the ecosystem, had the highest litter decomposition rate, and exhibited no significant positive and even some negative response to nitrogen additions. However, both disturbed and rehabilitated forests, which are still N limited due to previous land use history, exhibited slower litter decomposition rates with significant positive effects from nitrogen additions. These results suggest that litter decomposition and its responses to N addition in subtropical forests of China vary depending on the nitrogen status of the ecosystem.

Response of litter decomposition to simulated N deposition in disturbed, rehabilitated and mature forests in subtropical China

Litter decomposition represents one of the largest annual fluxes of carbon (C) from terrestrial ecosystems, particularly for tropical forests, which are generally characterized by high net primary productivity and litter turnover. We used data from the Long-Term Intersite Decomposition Experiment (LIDET) to (1) determine the relative importance of climate and litter quality as predictors of decomposition rates, (2) compare patterns in root and leaf litter decomposition, (3) identify controls on net nitrogen (N) release during decay, and (4) compare LIDETrates with native species studies across five bioclimatically diverse neotropical forests. Leaf and root litter decomposed fastest in the lower montane rain and moist forests and slowest in the seasonally dry forest. The single best predictor of leaf litter decomposition was the climate decomposition index (CDI), explaining 51% of the variability across all sites. The strongest models for predicting leaf decomposition combined climate and litter chemistry, and included CDI and lignin (R 2 50.69), or CDI, N and nonpolar extractives (R 2 50.69). While we found no significant differences in decomposition rates between leaf and root litter, drivers of decomposition differed for the two tissue types. Initial stages of decomposition, determined as the time to 50% mass remaining, were driven primarily by precipitation for leaf litter (R 2 50.93) and by temperature for root litter (R 2 50.86). The rate of N release from leaf litter was positively correlated with initial N concentrations; net N immobilization increased with decreasing initial N concentrations. This study demonstrates that decomposition is sensitive to climate within and across tropical forests. Our results suggest that climate change and increasing N deposition in tropical forests are likely to result in significant changes to decomposition rates in this biome.

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Controls on long-term root and leaf litter decomposition in neotropical forests

Status of the World’s Soil Resources Main report

Carbon storage and release in Indonesian peatlands since the last deglaciation

Tropical peatland fires play a significant role in the context of global warming through emissions of substantial amounts of greenhouse gases. However, the state of knowledge on carbon loss from these fires is still poorly developed with few studies reporting the associated mass of peat consumed. Furthermore, spatial and temporal variations in burn depth have not been previously quantified. This study presents the first spatially explicit investigation of fire-driven tropical peat loss and its variability. An extensive airborne Light Detection and Ranging data set was used to develop a prefire peat surface modelling methodology, enabling the spatially differentiated quantification of burned area depth over the entire burned area. We observe a strong interdependence between burned area depth, fire frequency and distance to drainage canals. For the first time, we show that relative burned area depth decreases over the first four fire events and is constant thereafter. Based on our results, we revise existing peat and carbon loss estimates for recurrent fires in drained tropical peatlands. We suggest values for the dry mass of peat fuel consumed that are 206 t ha(-1) for initial fires, reducing to 115 t ha(-1) for second, 69 t ha(-1) for third and 23 t ha(-1) for successive fires, which are 58-7% of the current IPCC Tier 1 default value for all fires. In our study area, this results in carbon losses of 114, 64, 38 and 13 t C ha(-1) for first to fourth fires, respectively. Furthermore, we show that with increasing proximity to drainage canals both burned area depth and the probability of recurrent fires increase and present equations explaining burned area depth as a function of distance to drainage canal. This improved knowledge enables a more accurate approach to emissions accounting and will support IPCC Tier 2 reporting of fire emissions.

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Variable carbon losses from recurrent fires in drained tropical peatlands

. Estimation of belowground carbon stocks in tropical wetland forests requires funding for laboratory analyses and suitable facilities, which are often lacking in developing nations where most tropical wetlands are found. It is therefore beneficial to develop simple analytical tools to assist belowground carbon estimation where financial and technical limitations are common. Here we use published and original data to describe soil carbon density (kgC m−3; Cd) as a function of bulk density (gC cm−3; Bd), which can be used to rapidly estimate belowground carbon storage using Bd measurements only. Predicted carbon densities and stocks are compared with those obtained from direct carbon analysis for ten peat swamp forest stands in three national parks of Indonesia. Analysis of soil carbon density and bulk density from the literature indicated a strong linear relationship (Cd = Bd × 495.14 + 5.41, R2 = 0.93, n = 151) for soils with organic C content > 40%. As organic C content decreases, the relationship between Cd and Bd becomes less predictable as soil texture becomes an important determinant of Cd. The equation predicted belowground C stocks to within 0.92% to 9.57% of observed values. Average bulk density of collected peat samples was 0.127 g cm−3, which is in the upper range of previous reports for Southeast Asian peatlands. When original data were included, the revised equation Cd = Bd × 468.76 + 5.82, with R2 = 0.95 and n = 712, was slightly below the lower 95% confidence interval of the original equation, and tended to decrease Cd estimates. We recommend this last equation for a rapid estimation of soil C stocks for well-developed peat soils where C content > 40%.

/pdf/a-cost-efficient-method-to-assess-carbon-stocks-in-tropical-49cxr2cz80.pdf

A cost-efficient method to assess carbon stocks in tropical peat soil

Decomposition of leaf litter of four tree species in a subtropical evergreen broad-leaved forest, Okinawa Island, Japan

The seasonal patterns of litterfalls, such as leaves, woody organs, reproductive parts, insect bodies, and feces, were investigated monthly for three years from January 1999 to December 2001 in a subtropical evergreen broad-leaved forest in the northern part of Okinawa Island, Japan. The total annual litterfall was estimated at 6.66-8.28 Mg ha-1 yr-1. The litterfall was mainly composed of leaves (52.4- 54.8% of the total litterfall), about half of which were from Castanopsis Sieboldii. The species composition of leaf litter was almost consistently the same every month for a year. The leaf litter was separated into two groups: one group, which had a high proportion of the total leaf litter, included C. Sieboldii, Schima Wallichii, Elaeocarpus japonicus, and Cinnamomum Doederleinii; the other group included the other 44 species. The species diversity indexes of leaf litter H’ and J’ showed their minimum values in March, when the leaf litter reached its maximum. There was no significant difference in species rank among years in terms of the annual amount of leaf litter. The mean leaf litter per tree of a given species was significantly proportional to its corresponding basal area, regardless of species and year. The degree of overlap in the seasonal patterns of litterfall components showed that leaves, insect bodies, and reproductive parts are nearly overlapped, but woody organs and feces are more or less exclusive to the other three components. Although the seasonal patterns in leaf litter of C. Sieboldii, S. Wallichii, and E. japonicus were nearly overlapped, the seasonal pattern in leaf litter of C. Doederleinii was almost independent of those of the other three species.

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Litterfall of a subtropical evergreen broad-leaved forest in Okinawa island, Japan

Species Composition and Above Ground Biomass (AGB) of a pine forest at Bodogol in Gunung Gede Pangrango National Park (GGPNP) was conducted over three years. A permanent plot of 200 x 50 m2 was established and was then divided into 100 subplots sized 10 x 10 m2. The highest Important Value was reached for Tusam (Pinus merkusii) with IV=140.9, followed by Calliandra calothyrsus (94.4) and Piper aduncum (28.9). In contrast, the Relative Growth Rate of C. callothyrsus was highest compared to other dominant trees. The number was highly contributed by a class distribution of less than 10 cm, generally filled by other species except pine trees, that were found on class distribution of more or equal to 30 cm. The changes of AGB ranged from 247.2 to 328.6 ton ha-1, and the trend of increasing AGB may be attributed to the growth of pine trees. However, it showed that there are significant differences between 2009 and 2010 - 2011 (one way ANOVA, P<0.05).

Species composition and above ground biomass of a pine forest at Bodogol, Gunung Gede Pangrango National Park, West Java

A study on the biomass and carbon stock estimation of Pinus merkusii Jungh. & de Vriese plantation has been conducted on 17-years and 30-years old pine forest in Gunung Bunder, Halimun Salak National Park. The method used was the allometric with non destructive technique. The results showed that pine trees density of 30-years old pine was 542 trees ha-1 ; the basal area (BA) was 26.8 m2 ha-1; trees density of 17-years old pine was 1,398 tree ha-1 with BA was 36.2 m2 ha-1. The estimation of biomass, carbon sinks and CO2 sequestration of 30-years old pine were 203.7, 96.5 and 354.2 ton ha-1, respectively. Meanwhile, the estimation of biomass, carbon sinks and CO2 sequestration of 17-years old pine were 188.3, 86.8 and 318.5 ton ha-1, respectively. Value of the environmental services derived from the CO2 absorption for the development of a pine forest ranged from US.$ 1,847.09 to 2,054.22, at two ages of pine trees.

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Laode Alhamd

Papers

A cost-efficient method to assess carbon stocks in tropical peat soil

Decomposition of leaf litter of four tree species in a subtropical evergreen broad-leaved forest, Okinawa Island, Japan

Litterfall of a subtropical evergreen broad-leaved forest in Okinawa island, Japan

Species composition and above ground biomass of a pine forest at Bodogol, Gunung Gede Pangrango National Park, West Java

ESTIMASI BIOMASA DAN KARBON TERSIMPAN PADA Pinus merkusii Jungh. & de Vriese DI HUTAN PINUS GN. BUNDER, TN. GN. HALIMUN SALAK