title: A new framework for evaluating the impacts of drought on net primary productivity of grassland.
abstract: This paper presented a valuable framework for evaluating the impacts of droughts (single factor) on grassland ecosystems. This framework was defined as the quantitative magnitude of drought impact that unacceptable short-term and long-term effects on ecosystems may experience relative to the reference standard. Long-term effects on ecosystems may occur relative to the reference standard. Net primary productivity (NPP) was selected as the response indicator of drought to assess the quantitative impact of drought on Inner Mongolia grassland based on the Standardized Precipitation Index (SPI) and BIOME-BGC model. The framework consists of six main steps: 1) clearly defining drought scenarios, such as moderate, severe and extreme drought; 2) selecting an appropriate indicator of drought impact; 3) selecting an appropriate ecosystem model and verifying its capabilities, calibrating the bias and assessing the uncertainty; 4) assigning a level of unacceptable impact of drought on the indicator; 5) determining the response of the indicator to drought and normal weather state under global-change; and 6) investigating the unacceptable impact of drought at different spatial scales. We found NPP losses assessed using the new framework were more sensitive to drought and had higher precision than the long-term average method. Moreover, the total and average losses of NPP are different in different grassland types during the drought years from 1961-2009. NPP loss was significantly increased along a gradient of increasing drought levels. Meanwhile, NPP loss variation under the same drought level was different in different grassland types. The operational framework was particularly suited for integrative assessing the effects of different drought events and long-term droughts at multiple spatial scales, which provided essential insights for sciences and societies that must develop coping strategies for ecosystems for such events.
authors.affiliation: Academy of Disaster Reduction and Emergency Management, MOCA/MOE, Beijing Normal University, Beijing 100875, China; China Institute of Water Resources and Hydropower Research, Beijing 100044, China; Center for Drought and Risk Research, Beijing Normal University, Beijing 100875, China.
authors.forename: Tianjie
authors.initials: T
authors.lastname: Lei
authors.affiliation: Academy of Disaster Reduction and Emergency Management, MOCA/MOE, Beijing Normal University, Beijing 100875, China; Center for Drought and Risk Research, Beijing Normal University, Beijing 100875, China. Electronic address: jjwu@bnu.edu.cn.
authors.forename: Jianjun
authors.initials: J
authors.lastname: Wu
authors.affiliation: Academy of Disaster Reduction and Emergency Management, MOCA/MOE, Beijing Normal University, Beijing 100875, China; Center for Drought and Risk Research, Beijing Normal University, Beijing 100875, China.
authors.forename: Xiaohan
authors.initials: X
authors.lastname: Li
authors.affiliation: Academy of Disaster Reduction and Emergency Management, MOCA/MOE, Beijing Normal University, Beijing 100875, China; Center for Drought and Risk Research, Beijing Normal University, Beijing 100875, China.
authors.forename: Guangpo
authors.initials: G
authors.lastname: Geng
authors.affiliation: Department of Geography/CGCEO, Michigan State University, East Lansing, MI 48823, USA.
authors.forename: Changliang
authors.initials: C
authors.lastname: Shao
authors.affiliation: Academy of Disaster Reduction and Emergency Management, MOCA/MOE, Beijing Normal University, Beijing 100875, China; Center for Drought and Risk Research, Beijing Normal University, Beijing 100875, China.
authors.forename: Hongkui
authors.initials: H
authors.lastname: Zhou
authors.affiliation: Academy of Disaster Reduction and Emergency Management, MOCA/MOE, Beijing Normal University, Beijing 100875, China; Center for Drought and Risk Research, Beijing Normal University, Beijing 100875, China.
authors.forename: Qianfeng
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Academy of Disaster Reduction and Emergency Management, MOCA/MOE, Beijing Normal University, Beijing 100875, China; Center for Drought and Risk Research, Beijing Normal University, Beijing 100875, China.
authors.forename: Leizhen
authors.initials: L
authors.lastname: Liu
mesh_terms: D018533:Biomass; D002681:China; D055864:Droughts; D004784:Environmental Monitoring / Q000379:methods*; D065948:Grassland; D008962:Models, Theoretical
keywords: Assessing framework; BIOME-BGC; Drought impact; Grasslands; NPP; SPI