title: The impacts of climate change and human activities on biogeochemical cycles on the Qinghai-Tibetan Plateau.
abstract: With a pace of about twice the observed rate of global warming, the temperature on the Qinghai-Tibetan Plateau (Earth's 'third pole') has increased by 0.2 °C per decade over the past 50 years, which results in significant permafrost thawing and glacier retreat. Our review suggested that warming enhanced net primary production and soil respiration, decreased methane (CH(4)) emissions from wetlands and increased CH(4) consumption of meadows, but might increase CH(4) emissions from lakes. Warming-induced permafrost thawing and glaciers melting would also result in substantial emission of old carbon dioxide (CO(2)) and CH(4). Nitrous oxide (N(2)O) emission was not stimulated by warming itself, but might be slightly enhanced by wetting. However, there are many uncertainties in such biogeochemical cycles under climate change. Human activities (e.g. grazing, land cover changes) further modified the biogeochemical cycles and amplified such uncertainties on the plateau. If the projected warming and wetting continues, the future biogeochemical cycles will be more complicated. So facing research in this field is an ongoing challenge of integrating field observations with process-based ecosystem models to predict the impacts of future climate change and human activities at various temporal and spatial scales. To reduce the uncertainties and to improve the precision of the predictions of the impacts of climate change and human activities on biogeochemical cycles, efforts should focus on conducting more field observation studies, integrating data within improved models, and developing new knowledge about coupling among carbon, nitrogen, and phosphorus biogeochemical cycles as well as about the role of microbes in these cycles.
authors.affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, China; Laboratory for Ecological Forecasting and Global Change, College of Forestry, Northwest Agriculture and Forest University, Yangling, 712100, China; Zoige Peatland and Global Change Research Station, Chinese Academy of Sciences, Hongyuan, 624400, China.
authors.forename: Huai
authors.initials: H
authors.lastname: Chen
authors.forename: Qiuan
authors.initials: Q
authors.lastname: Zhu
authors.forename: Changhui
authors.initials: C
authors.lastname: Peng
authors.forename: Ning
authors.initials: N
authors.lastname: Wu
authors.forename: Yanfen
authors.initials: Y
authors.lastname: Wang
authors.forename: Xiuqing
authors.initials: X
authors.lastname: Fang
authors.forename: Yongheng
authors.initials: Y
authors.lastname: Gao
authors.forename: Dan
authors.initials: D
authors.lastname: Zhu
authors.forename: Gang
authors.initials: G
authors.lastname: Yang
authors.forename: Jianqing
authors.initials: J
authors.lastname: Tian
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Kang
authors.forename: Shilong
authors.initials: S
authors.lastname: Piao
authors.forename: Hua
authors.initials: H
authors.lastname: Ouyang
authors.forename: Wenhua
authors.initials: W
authors.lastname: Xiang
authors.forename: Zhibin
authors.initials: Z
authors.lastname: Luo
authors.forename: Hong
authors.initials: H
authors.lastname: Jiang
authors.forename: Xingzhang
authors.initials: X
authors.lastname: Song
authors.forename: Yao
authors.initials: Y
authors.lastname: Zhang
authors.forename: Guirui
authors.initials: G
authors.lastname: Yu
authors.forename: Xinquan
authors.initials: X
authors.lastname: Zhao
authors.forename: Peng
authors.initials: P
authors.lastname: Gong
authors.forename: Tandong
authors.initials: T
authors.lastname: Yao
authors.forename: Jianghua
authors.initials: J
authors.lastname: Wu
mesh_terms: D000383:Agriculture; D000818:Animals; D002681:China; D057231:Climate Change; D017753:Ecosystem; D006801:Humans; D010944:Plants; D018609:Tibet
keywords: carbon budget; ice retreat; intact ecosystems; land use change; permafrost