Land tenure and productivity: evidence from rural China

For the 640 million farmers (i.e. 47% of the total population) living in rural China as of 2012, land is a resource of significant value. China has experimented with different forms of land tenure arrangements, which have been widely recognised as being vital to the productivity of agriculture which in turn is critical to poverty alleviation. The changes in land tenure arrangements over the past half a century have included a shift from privately owned to collectively owned land, from the offer of 15-year use rights to perpetual use rights to the land under cultivation, from the issue of informal land certificates to the currently (i.e. as of 2014) ongoing formal land certification program (RLRC). All these changes have the potential to affect farm productivity and thus impact rural poverty. This thesis aims to examine how the changing land tenure arrangements have affected productivity at the level of individual farms, and the policy lessons on how to improve productivity and household income. To answer the aforementioned questions, two levels of research were conducted. Firstly, data at the level of the 31 provinces over a 60-year period was analysed to investigate the link between grain productivity and land tenure arrangements. The findings show that land tenure dummies that stand for land use rights and the right to transfer rights to use the land have had positive effects on grain productivity. Secondly, farm-level data was collected via a purpose-designed survey. This data was analysed using regression and matching methods on certified and uncertified plots. The quantitative estimates on the impact of land certification on farm-level productivity and income shows that use rights secured through certification induces farmers to: (i) invest more in land; (ii) transfer land to more productive farmers, thereby increasing land productivity; and, (iii) participate in the land rental markets which contributes to household income and improves allocative efficiency. In summary, the thesis is that land tenure reform is critical to growth in productivity and income for small holders. These findings lend support to the ongoing land reforms throughout China

Spatial-Temporal Variability of Soil Organic Matter in Urban Fringe over 30 Years: A Case Study in Northeast China.

The study on soil organic matter (SOM) is of great importance to regional cultivated land use and protection. Based on data collected via continuous and high-density soil samples (0-20 cm) and socio-economic data collected from household survey and local bureau of statistics, this study employs geostatistics and economic statistical methods to investigate the spatial-temporal variation of SOM contents during 1980-2010 in the urban fringe of Sujiatun district in Shenyang City, China. We find that: (1) as to temporal variation, SOM contents in the study sites decreased from 30.88 g/kg in 1980 to 22.63 g/kg in 2000. It further declined to 20.07 g/kg in 2010; (2) in terms of spatial variation, the closer to city center, the more decline of SOM contents. Contrarily, SOM contents could even rise in outer suburb area; and (3) SOM content variation may be closely related to human factors such as farmers’ land use target and behaviour including inputs of chemical and organic fertilizers, types of crops and etc. These findings are conductive to grasp the overall trend of SOM variation and the influence of farmers’ land use behaviour on it. Furthermore, they could provide support for policymakers to agricultural planning and land use monitoring, which consequently aids the improvement of soil quality and food production in the urban fringe areas

Optogenetic Control of Voltage-Gated Calcium Channels

Voltage-gated Ca(2+) (CaV ) channels mediate Ca(2+) entry into excitable cells to regulate a myriad of cellular events following membrane depolarization. We report the engineering of RGK GTPases, a class of genetically encoded CaV channel modulators, to enable photo-tunable modulation of CaV channel activity in excitable mammalian cells. This optogenetic tool (designated optoRGK) tailored for CaV channels could find broad applications in interrogating a wide range of CaV -mediated physiological processes

Rapid formation of intense haze episodes via aerosol-boundary layer feedback in Beijing

Although much effort has been put into studying air pollution, our knowledge of the mechanisms of frequently occurring intense haze episodes in China is still limited. In this study, using 3 years of measurements of air pollutants at three different height levels on a 325m Beijing meteorology tower, we found that a positive aerosol-boundary layer feedback mechanism existed at three vertical observation heights during intense haze polluted periods within the mixing layer. This feedback was characterized by a higher loading of PM2.5 with a shallower mixing layer. Modelling results indicated that the presence of PM2.5 within the boundary layer led to reduced surface temperature, relative humidity and mixing layer height during an intensive haze episode. Measurements showed that the aerosol-boundary layer feedback was related to the decrease in solar radiation, turbulent kinetic energy and thereby suppression of the mixing layer. The feedback mechanism can explain the rapid formation of intense haze episodes to some extent, and we suggest that the detailed feedback mechanism warrants further investigation from both model simulations and field observations.Peer reviewe

Diversification of Genes Encoding Granule-Bound Starch Synthase in Monocots and Dicots Is Marked by Multiple Genome-Wide Duplication Events

Starch is one of the major components of cereals, tubers, and fruits. Genes encoding granule-bound starch synthase (GBSS), which is responsible for amylose synthesis, have been extensively studied in cereals but little is known about them in fruits. Due to their low copy gene number, GBSS genes have been used to study plant phylogenetic and evolutionary relationships. In this study, GBSS genes have been isolated and characterized in three fruit trees, including apple, peach, and orange. Moreover, a comprehensive evolutionary study of GBSS genes has also been conducted between both monocots and eudicots. Results have revealed that genomic structures of GBSS genes in plants are conserved, suggesting they all have evolved from a common ancestor. In addition, the GBSS gene in an ancestral angiosperm must have undergone genome duplication ∼251 million years ago (MYA) to generate two families, GBSSI and GBSSII. Both GBSSI and GBSSII are found in monocots; however, GBSSI is absent in eudicots. The ancestral GBSSII must have undergone further divergence when monocots and eudicots split ∼165 MYA. This is consistent with expression profiles of GBSS genes, wherein these profiles are more similar to those of GBSSII in eudicots than to those of GBSSI genes in monocots. In dicots, GBSSII must have undergone further divergence when rosids and asterids split from each other ∼126 MYA. Taken together, these findings suggest that it is GBSSII rather than GBSSI of monocots that have orthologous relationships with GBSS genes of eudicots. Moreover, diversification of GBSS genes is mainly associated with genome-wide duplication events throughout the evolutionary course of history of monocots and eudicots