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Extension of the rotation length in forest management has been highlighted in Article 3.4 of the Kyoto Protocol to help the countries in their commitments for reduction in greenhouse gas emissions. CO2FIX Model Ver.3.2 was used to examine the dynamics of carbon stocks (C stocks) in a rubber plantation in South Western China with the changing rotation lengths. To estimate the efficiency of increasing the rotation length as an Article 3.4 activity, study predicted that the rubber production and C stocks of the ecosystem increased with the increasing rotation (25, 30, 35, 40 and 45 years). While comparing the pace of growth both in economical (rubber production) and ecological (C stocks) terms in each rotation, 40 years rotation length showed maximum production and C stocks. After elongation of 40 year rotation to four consecutive cycles, it was concluded that the total C stocks of the ecosystem were 186.65 Mg ha(-1). The longer rotation lengths showed comparatively increased C stocks in below ground C stock after consecutive four rotations. The pace of C input (Mg C ha(-1) yr(-1)) and rubber production indicated that 40 years rotation is best suited for rubber plantation. The study has developed carbon mitigation based on four rotation scenarios. The possible stimulated increase in C stocks of the entire ecosystem after consecutive long rotations indicated that the emphasis must be paid on deciding the rotation of rubber plantation in SW China for reporting under article 3.4 of the Kyoto Protocol.

Aims The evolutionary history and functional traits of species can illuminate ecological processes supporting coexistence in diverse forest communities. However, little has been done in decoupling the relative importance of these mechanisms on the turnover of phylogenetic and functional characteristics across life stages and spatial scales. Therefore, this study aims to estimate the contribution of environment and dispersal on the turnover of phylogenetic and functional diversity across life stages and spatial scales, in order to build a coherent picture of the processes responsible for species coexistence. Methods We conducted the study in Xishuangbanna Forest Dynamics Plot in Yunnan Province, southwest China. We used four different spatial point process models to estimate the relative importance of dispersal limitation and environmental filtering. The functional traits and phylogenetic relationships of all individual trees were incorporated in the analyses to generate measures of dissimilarity in terms of pairwise and nearest-neighbor phylogenetic and functional characteristics across life stages and spatial scales. Important Findings We found non-random patterns of phylogenetic and functional turnover across life stages and spatial scales. Environmental filtering structured pairwise phylogenetic and functional beta diversity across spatial scales, while dispersal limitation alone, and in combination with environment filtering, shaped nearest neighbor phylogenetic and functional beta diversity. The relative importance of dispersal limitation and environmental filtering appeared to change with life stage but not with spatial scale. Our findings suggest that phylogenetic and functional beta diversity help to reveal the ecological processes responsible for evolutionary and functional assembly and highlight the importance of using a range of different metrics to gain full insights into these processes. [ABSTRACT FROM AUTHOR]

Litter inputs are expected to have a strong impact on soil N2O efflux. This study aimed to assess the effects of the litter decomposition process and nutrient efflux from litter to soil on soil N2O efflux in a tropical rainforest. A paired study with a control (L) treatment and a litter-removed (NL) treatment was followed for 2 years, continuously monitoring the effects of these treatments on soil N2O efflux, fresh litter input, decomposed litter carbon (LCI) and nitrogen (LNI), soil nitrate (NO3−-N), ammonium (NH4+-N), dissolved organic carbon (DOC), and dissolved nitrogen (DN). Soil N2O flux was 0.48 and 0.32 kg N2O-N ha−1 year−1 for the L and NL treatments, respectively. Removing the litter caused a decrease in the annual soil N2O emission by 33%. The flux values from the litter layer were higher in the rainy season as compared to the dry season (2.10 ± 0.28 vs. 1.44 ± 0.35 μg N m−2 h−1). The N2O fluxes were significantly correlated with the soil NO3−-N contents (P < 0.05), indicating that the N2O emission was derived mainly from denitrification as well as other NO3− reduction processes. Suitable soil temperature and moisture sustained by rainfall were jointly attributed to the higher soil N2O fluxes of both treatments in the rainy season. The N2O fluxes from the L were mainly regulated by LCI, whereas those from the NL were dominated jointly by soil NO3− content and temperature. The effects of LCI and LNI on the soil N2O fluxes were the greatest in the 2 months after litter decomposition. Our results show that litter may affect not only the variability in the quantity of N2O emitted, but also the mechanisms that govern N2O production. However, further studies are still required to elucidate the impacting mechanisms of litter decomposition on N2O emission from tropical forests. [ABSTRACT FROM AUTHOR]