Status and perspectives on secondary forests in tropical China. Paper prepared for the “Tropical secondary forests in Asia: Reality and perspectives’ workshop”. 10–14

ZAIZHI, Z. 2001. Status and perspectives on secondary forests in tropical China. Tropical China has relatively low forest cover and faces high pressures for its depleting forests. Following intensive exploitation of its forest resources over several decades, large areas of post-extraction secondary forests exist. These remaining natural forests play very important roles in water resources retention, and the supply of small-diameter timber, fuelwood, poles, and non-timber forest products for sustaining the livelihoods of mountain communities. However, the extent of these resources is fast diminishing and most of it is highly degraded.The paper illustrates that the transfer of forest-use rights to local communities can in fact lead to increased forest degradation when implemented in the context of a long history of changing policies on forest-use rights. The paper also suggests that a shortage of financial support, incentive mechanisms, management knowledge and techniques, the over-taxation of wood, and poverty are affecting the management and use of secondary forests. Policy requirements and management options need to be explored for overcoming the constraints to the ecologically and economically viable use of secondary forests, and the integrated development of the communities that depend on this resource. Key words: Tropical China -secondary forests -mountains -degraded land -local communities -policy change ZAIZHI, Z. 2001. Status dan perspektif terhadap hutan sekunder di tropika China. Secara relatif tropika China mempunyai litupan hutan yang rendah dan tekanan yang tinggi secara relatif. Ekoran eksploitasi secara intensif terhadap sumber hutan sejak beberapa dekad, wujud kawasan hutan sekunder selepas pengekstrakan yang luas. Hutan semula jadi yang masih tinggal memainkan peranan yang sangat penting sebagai penahan sumber air, dan pembekal balak bergaris pusat kecil, kayu api, kayu jaras serta keluaran hutan bukan-kayu untuk mengekalkan mata pencarian penduduk di kawasan pergunungan. Bagaimanapun, sumber-sumber ini berkurangan dengan cepat dan kebanyakannya rosak dengan teruknya. Artikel ini menerangkan bahawa pengalihan hak penggunaan hutan kepada penduduk tempatan menyebabkan pendegradan hutan meningkat apabila dilaksanakan dalam konteks sejarah pertukaran polisi tentang hak penggunaan hutan. Artikel ini juga mencadangkan bahawa kekurangan sokongan kewangan, mekanisme pemberian insentif, pengetahuan dan teknik pengurusan, di samping cukai yang tinggi ke atas kayu serta kemiskinan memberi kesan kepada pengurusan dan penggunaan hutan sekunder. Keperluan polisi dan pilihan pengurusan perlu diteliti untuk mengurangkan tekanan kepada penggunaan hutan sekunder yang berdaya maju dari segi ekologi dan ekonomi, dan pembangunan bersepadu penduduk yang bergantung kepada sumber-sumber ini

Simulation of direct radiative forcing of aerosols and their effects on East Asian climate using an interactive AGCM-aerosol coupled system

International audienceAn interactive system coupling the Beijing Climate Center atmospheric general circulation model (BCC_AGCM2. 0. 1) and the Canadian Aerosol Module (CAM) with updated aerosol emission sources was developed to investigate the global distributions of optical properties and direct radiative forcing (DRF) of typical aerosols and their impacts on East Asian climate. The simulated total aerosol optical depth (AOD), single scattering albedo, and asymmetry parameter were generally consistent with the ground-based measurements. Under all-sky conditions, the simulated global annual mean DRF at the top of the atmosphere was -2. 03 W m-2 for all aerosols including sulfate, organic carbon (OC), black carbon (BC), dust, and sea salt; the global annual mean DRF was -0. 23 W m-2 for sulfate, BC, and OC aerosols. The sulfate, BC, and OC aerosols led to decreases of 0. 58° and 0. 14 mm day-1 in the JJA means of surface temperature and precipitation rate in East Asia. The differences of land-sea surface temperature and surface pressure were reduced in East Asian monsoon region due to these aerosols, thus leading to the weakening of East Asian summer monsoon. Atmospheric dynamic and thermodynamic were affected due to the three types of aerosol, and the southward motion between 15°N and 30°N in lower troposphere was increased, which slowed down the northward transport of moist air carried by the East Asian summer monsoon, and moreover decreased the summer monsoon precipitation in south and east China. © 2011 Springer-Verlag

Signatures of the Protein Folding Pathway in Two-Dimensional Ultraviolet Spectroscopy

The function of protein relies on their folding to assume the proper structure. Probing the structural variations during the folding process is crucial for understanding the underlying mechanism. We present a combined quantum mechanics/molecular dynamics simulation study that demonstrates how coherent resonant nonlinear ultraviolet spectra can be used to follow the fast folding dynamics of a mini-protein, Trp-cage. Two dimensional ultraviolet signals of the backbone transitions carry rich information of both local (secondary) and global (tertiary) structures. The complexity of signals decreases as the conformational entropy decreases in the course of the folding process. We show that the approximate entropy of the signals provides a quantitative marker of protein folding status, accessible by both theoretical calculations and experiments

Monitoring the Folding of Trp-Cage Peptide by Two-Dimensional Infrared (2DIR) Spectroscopy

Protein folding is one of the most fundamental problems in modern molecular biology. Uncovering the detailed folding mechanism requires methods that can monitor the structures at high temporal and spatial resolution. Two-dimensional infrared (2DIR) spectroscopy is a new tool for studying protein structures and dynamics with high time resolution. Using atomistic molecular dynamics simulations, we illustrate the folding process of Trp-cage along the dominant pathway on free energy landscape by analyzing nonchiral and chiral coherent 2DIR spectra along the pathway. Isotope-labeling is used to reveal residue-specific information. We show that the high resolution structural sensitivity of 2DIR can differentiate the ensemble evolution of protein, and thus provides a microscopic picture of the folding process