Floristic Characteristics of the Rare and Endangered Plant Species in North Guangdong and Their Conservation Strategies The processes of land rocky desertification in typical Karst Mountain area: a case study in the karst mountain area of North Guangdong The Characteristic of Physiological Ecology of the Main Tree Species Used for Afforestation at Limestone Regions in North Guangdong Evaluation for the Growth Regularity of Progenies from Yingde Loblolly Pine Seed Orchard in North Guangdong Guilds of Soil Fauna after Ice-Snow Disaster in North Guangdong