The above-ground net primary production(ANPP) and the precipitation-use efficiency(PUE) regulate the carbon and water cycles in grassland ecosystems, but the relationships among the ANPP, PUE and precipitation are sti...The above-ground net primary production(ANPP) and the precipitation-use efficiency(PUE) regulate the carbon and water cycles in grassland ecosystems, but the relationships among the ANPP, PUE and precipitation are still controversial. We selected 717 grassland sites with ANPP and mean annual precipitation(MAP) data from 40 publications to characterize the relationships ANPP–MAP and PUE–MAP across different grassland types. The MAP and ANPP showed large variations across all grassland types, ranging from 69 to 2335 mm and 4.3 to 1706 g m^(-2), respectively. The global maximum PUE ranged from 0.19 to 1.49 g m^(-2) mm^(-1) with a unimodal pattern. Analysis using the sigmoid function explained the ANPP–MAP relationship best at the global scale. The gradient of the ANPP–MAP graph was small for arid and semi-arid sites(MAP <400 mm). This study improves our understanding of the relationship between ANPP and MAP across dry grassland ecosystems. It provides new perspectives on the prediction and modeling of variations in the ANPP for different grassland types along precipitation gradients.展开更多
Plant biomass, species diversity and net primary productivity are presented for herb layer of banj oak （Quercus leucotrichophora A. Camus）-chir pine （Pinus roxburghii Sarg.） mixed forest in Kumaun, central Himalay...Plant biomass, species diversity and net primary productivity are presented for herb layer of banj oak （Quercus leucotrichophora A. Camus）-chir pine （Pinus roxburghii Sarg.） mixed forest in Kumaun, central Himalaya, India. The species diversity declined from a maximum （3.56） in September to a minimum （2.11） in December. The monthly live shoots biomass exhibited a single peak growth pattern with highest live shoot biomass of 185 g·m^-2 in August. The seasonal pattem showed that the maximum above-ground production （131 g·m^-2） occurred during the rainy season and the minimum （1 g·m^-2） during winter season. The be- low-ground production was maximum during winter season （84 g·m^2） and minimum during summer season （34 g＇m＇2）. The annual net shoot production was 171 g·^2m^-1 and total below-ground production was 165 g·m^2. Of the total input 61% was channeled to above-ground parts and 39% to below-ground parts. Transfer of live shoots to dead shoots compartments and that of dead shoots to litter compartments was 61% and 66%, respectively. The total dry matter disappearance was 61% of the total input within annual cycle. The herb layer showed a net accumulation of organic matter, indicating the seral nature of the community.展开更多
基金jointly funded by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20020401)the Young Foundation of Institute of Mountain Hazard and Environment(SDS-QN-1702)National Natural Science Foundation of China(Grant No.41571205)
文摘The above-ground net primary production(ANPP) and the precipitation-use efficiency(PUE) regulate the carbon and water cycles in grassland ecosystems, but the relationships among the ANPP, PUE and precipitation are still controversial. We selected 717 grassland sites with ANPP and mean annual precipitation(MAP) data from 40 publications to characterize the relationships ANPP–MAP and PUE–MAP across different grassland types. The MAP and ANPP showed large variations across all grassland types, ranging from 69 to 2335 mm and 4.3 to 1706 g m^(-2), respectively. The global maximum PUE ranged from 0.19 to 1.49 g m^(-2) mm^(-1) with a unimodal pattern. Analysis using the sigmoid function explained the ANPP–MAP relationship best at the global scale. The gradient of the ANPP–MAP graph was small for arid and semi-arid sites(MAP <400 mm). This study improves our understanding of the relationship between ANPP and MAP across dry grassland ecosystems. It provides new perspectives on the prediction and modeling of variations in the ANPP for different grassland types along precipitation gradients.
文摘Plant biomass, species diversity and net primary productivity are presented for herb layer of banj oak （Quercus leucotrichophora A. Camus）-chir pine （Pinus roxburghii Sarg.） mixed forest in Kumaun, central Himalaya, India. The species diversity declined from a maximum （3.56） in September to a minimum （2.11） in December. The monthly live shoots biomass exhibited a single peak growth pattern with highest live shoot biomass of 185 g·m^-2 in August. The seasonal pattem showed that the maximum above-ground production （131 g·m^-2） occurred during the rainy season and the minimum （1 g·m^-2） during winter season. The be- low-ground production was maximum during winter season （84 g·m^2） and minimum during summer season （34 g＇m＇2）. The annual net shoot production was 171 g·^2m^-1 and total below-ground production was 165 g·m^2. Of the total input 61% was channeled to above-ground parts and 39% to below-ground parts. Transfer of live shoots to dead shoots compartments and that of dead shoots to litter compartments was 61% and 66%, respectively. The total dry matter disappearance was 61% of the total input within annual cycle. The herb layer showed a net accumulation of organic matter, indicating the seral nature of the community.
