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Abstract. Grassland ecosystem is important for climatic regulation, maintaining the soil and water. Research on the grassland monitoring method could provide effective reference for grassland resource investigation. In this study, we used the vegetation index method for grassland classification. There are several types of climate in China. Therefore, we need to use China's Main Climate Zone Maps and divide the study region into four climate zones. Based on grassland classification system of the first nation-wide grass resource survey in China, we established a new grassland classification system which is only suitable for this research. We used MODIS images as the basic data resources, and use the expert classifier method to perform grassland classification. Based on the1:1,000,000 Grassland Resource Map of China, we obtained the basic distribution of all the grassland types and selected 20 samples evenly distributed in each type, then used NDVI/EVI product to summarize different spectral features of different grassland types. Finally, we introduced other classification auxiliary data, such as elevation, accumulate temperature (AT), humidity index (HI) and rainfall. China's nation-wide grassland classification map is resulted by merging the grassland in different climate zone. The overall classification accuracy is 60.4%. The result indicated that expert classifier is proper for national wide grassland classification, but the classification accuracy need to be improved.

A Zn-based coating with durable hydrophobicity and good corrosion resistance was formed on a mild steel substrate, which involves electroplating Zn from a non-aqueous electrolyte, followed by passivation in an oleic acid (OA) solution. The electrodeposited Zn coatings were porous, which facilitated the formation of a chemical conversion layer of Zn oleate (ZO) during OA passivation. The Zn coating after passivation had a twolayer structure, which included an outer layer of ZO with a thickness of ~26 μm and an inner layer of Zn with a thickness of ~6 μm. The outer layer ZO is a type of metal soap with a smooth surface and durable hydrophobicity, such that water droplets can easily slip off its surface. Corrosion testing and electrochemical measurements in 3.5 wt.% NaCl aqueous solution indicate that the Zn coating after OA passivation exhibits outstanding anti-corrosion properties compared with those exhibited by pure Zn coating. The corrosion products and mechanism of the two-layer coating were explored. This study shows that smooth metal oleate coatings can provide hydrophobicity and corrosion resistance simultaneously to mild steel substrates.

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