Changes in Nutrient Concentrations and Limitations of Poyang Lake Associated with Socioeconomic Development in the Watershed from 1978 to 2021,Changes in Nutrient Concentrations and Limitations of Poyang Lake Associated with Socioeconomic Development in the Watershed from 1978 to 2021,Comparative analysis of carbon footprint between conventional smallholder operation and innovative largescale farming of urban agriculture in Beijing, China [PeerJ],Urban Expansion and Farmland Loss in Beijing during 1980–2015,Urban Expansion and Farmland Loss in Beijing during 1980–2015