Litter Decomposition of Emergent Plants along an Elevation Gradient in Wetlands of Yunnan Plateau,China

The decomposition of plant litter is a key process of litter decomposition to global climate warming in plateau in the flows of energy and nutrients in ecosystems. However, the response wetlands remains largely unknown. In this study, we conducted a one-year litter decomposition experiment along an elevation gradient from 1891 m to 3260 m on the Yurman Plateau of Southwest China, using different litter types to determine the influences of climate change, litter quality and microenvironment on the decomposition rate. The results showed that the average decomposition rate （K） increased from 0.608 to 1.152, and the temperature sensitivity of litter mass losses was approximately 4.98%/℃ along the declining elevation gradient. Based on a correlation analysis, N concentrations and C ： N ratios in the litter were the best predictors of the decomposition rate, with significantly positive and negative correlations, respectively. Additionally, the cumulative effects of decomposition were clearly observed in the mixtures of Scirpus tabernaemontani and Zizania caduciflora. Moreover, the litter decomposition rate in the water was higher than that in the sediment, especially in high-elevation areas where the microenvironment was significantly affected by temperature. These results suggest that future climate warming will have significant impacts on plateau wetlands, which have important fimctions in biogeochemical cycling in cold highland ecosystems.

Comparisons of Two Cloud-Detection Schemes for Infrared Radiance Observations

The cloud-detection procedure developed by McNally and Watts(MW03) was added to the Weather Research and Forecasting Data Assimilation System. To provide some guidelines for setting up cloud-detection schemes, this study compares the MW03 scheme to the Multivariate and Minimum Residual(MMR) scheme for both simulated and real Advanced Infrared Sounder(AIRS) radiances. Results show that there is a high level of consistency between the results from simulated and real AIRS data. As expected, both cloud-detection schemes perform well in finding the cloud-contaminated channels based on the channels' peak levels. The clouddetection results from MW03 are sensitive to the prescribed brightness temperature innovation threshold and brightness temperature gradient threshold. When increasing the brightness temperature innovation threshold for MW03 to roughly eight times the default threshold, the two cloud-detection schemes produce consistent data rejection distributions overall for high channels. MMR generally retains more data for long-wave channels. For both cloud-detection schemes, there is a high level of consistency between the cloud-free pixels and the visible/near-IR(Vis/NIR) cloud mask.

Conceptual Framework for Key Element Identification in Important Agricultural Heritage Systems(IAHS):Case of Honghe Hani Rice Terraces System in China

With the continuous emergence of global development problems,the dynamic conservation and sustainable development of Important Agricultural Heritage Systems(IAHS)have been assigned greater importance.However,due to the complex structure,multi-component,dynamic,and open characteristics of IAHS,there are neglected problems which need to be solved in conservation practice,such as component element ambiguity,obscurity of the conservation redline,etc.This study defined the concept of key elements(KE)of IAHS,put forward a conceptual framework of KE identification,conducted empirical research by taking Honghe County of Honghe Hani Rice Terraces System(HHRTS)as an example and analyzed the level of recognition motivations for different stakeholder groups.The following conclusions were drawn:1)The KE of HHRTS are grain crops,rice species biodiversity,terrace construction and maintenance technique,Hani traditional festivals,Hani traditional foods,and virgin forest;2)The reasons behind the KE priorities of farmers,businessmen and tourists were at the micro level,the reasons of officers were at the middle level and the reasons of researchers were at the macro level.The empirical study conducted in HHRTS showed that the proposed conceptual framework could identify KE of IAHS effectively,and provided a theoretical perspective for the structuring of and essential need for IAHS research.Moreover,the KE recognition levels of different stakeholder groups reflected their potential action strategies.We should focus on the coherence of policies and measures in both the microscale and macroscale to balance the diversified demands of stakeholders,and to stimulate their enthusiasm for participation in the conservation in order to improve the management level of IAHS sites.