The capability of an improved Dynamic Global Vegetation Model （DGVM） in reproducing the impact of climate on the terrestrial ecosystem is evaluated. The new model incorporates the Community Land Model- DGVM （CLM3.0...The capability of an improved Dynamic Global Vegetation Model （DGVM） in reproducing the impact of climate on the terrestrial ecosystem is evaluated. The new model incorporates the Community Land Model- DGVM （CLM3.0-DGVM） with a submodel for temperate and boreal shrubs, as well as other revisions such as the ＂two-leaf＂ scheme for photosynthesis and the definition of fractional coverage of plant functional types （PFTs）. Results show that the revised model may correctly reproduce the global distribution of temperate and boreal shrubs, and improves the model performance with more realistic distribution of di？erent vege- tation types. The revised model also correctly reproduces the zonal distributions of vegetation types. In reproducing the dependence of the vegetation distribution on climate conditions, the model shows that the dominant regions for trees, grasses, shrubs, and bare soil are clearly separated by a climate index derived from mean annual precipitation and temperature, in good agreement with the CLM4 surface data. The dominant plant functional type mapping to a two dimensional parameter space of mean annual temperature and precipitation also qualitatively agrees with the results from observations and theoretical ecology studies.展开更多
ABSTRACT The lAP Dynamic Global Vegetation Model （IAP-DGVM） has been developed to simulate the distribution and structure of global vegetation within the framework of Earth System Models. It incorporates our group...ABSTRACT The lAP Dynamic Global Vegetation Model （IAP-DGVM） has been developed to simulate the distribution and structure of global vegetation within the framework of Earth System Models. It incorporates our group＇s recent developments of major model components such as the shrub sub-model, establishment and competition parameterization schemes, and a process-based fire parameterization of intermediate complexity. The model has 12 plant functional types, including seven tree, two shrub, and three grass types, plus bare soil. Different PFTs are allowed to coexist within a grid cell, and their state variables are updated by various governing equations describing vegetation processes from fine-scale biogeophysics and biogeochemistry, to individual and population dynamics, to large-scale biogeography. Environmental disturbance due to fire not only affects regional vegetation competition, but also influences atmospheric chemistry and aerosol emissions. Simulations under observed atmospheric conditions showed that the model can correctly reproduce the global distribution of trees, shrubs, grasses, and bare soil. The simulated global dominant vegetation types reproduce the transition from forest to grassland （savanna） in the tropical region, and from forest to shrubland in the boreal region, but overestimate the region of temperate forest.展开更多
In the past several decades, dynamic global vegetation models（DGVMs） have been the most widely used and appropriate tool at the global scale to investigate vegetation-climate interactions. At the Institute of Atmosp...In the past several decades, dynamic global vegetation models（DGVMs） have been the most widely used and appropriate tool at the global scale to investigate vegetation-climate interactions. At the Institute of Atmospheric Physics, a new version of DGVM（IAP-DGVM） has been developed and coupled to the Common Land Model（CoLM） within the framework of the Chinese Academy of Sciences＇ Earth System Model（CAS-ESM）. This work reports the performance of IAP-DGVM through comparisons with that of the default DGVM of CoLM（CoLM-DGVM） and observations. With respect to CoLMDGVM, IAP-DGVM simulated fewer tropical trees, more ＂needleleaf evergreen boreal tree＂ and ＂broadleaf deciduous boreal shrub＂, and a better representation of grasses. These contributed to a more realistic vegetation distribution in IAP-DGVM,including spatial patterns, total areas, and compositions. Moreover, IAP-DGVM also produced more accurate carbon fluxes than CoLM-DGVM when compared with observational estimates. Gross primary productivity and net primary production in IAP-DGVM were in better agreement with observations than those of CoLM-DGVM, and the tropical pattern of fire carbon emissions in IAP-DGVM was much more consistent with the observation than that in CoLM-DGVM. The leaf area index simulated by IAP-DGVM was closer to the observation than that of CoLM-DGVM; however, both simulated values about twice as large as in the observation. This evaluation provides valuable information for the application of CAS-ESM, as well as for other model communities in terms of a comparative benchmark.展开更多
Using the regional terrestrial Net Primary Production （NPP） from different observations and models over China, we validated the NPP simulations and explored the relationship between NPP and climate variation at inte...Using the regional terrestrial Net Primary Production （NPP） from different observations and models over China, we validated the NPP simulations and explored the relationship between NPP and climate variation at interannual and decadal scales in the Modified Sheffield Dynamic Global Vegetation Model （M-SDGVM） during 1981–2000. M-SDGVM shows agreement with the NPP data from 743 sites under the Global Primary Production Data Initiative （GPPDI）. The spatial and the zonal averaged NPP of M-SDGVM agree well with different historic datasets and are closest to the IGBP NPP. Compared to the 1980s, NPP in the 1990s increases in most of China with a high degree of spatial heterogeneity. The multi-year mean NPP of forest types is reasonably modeled （above 500 g C m-2 yr-1 ） while that of C 3 path of photosynthesis （C 3 ） grasslands is underestimated. The NPP of 7 M-SDGVM main plant functional types （PFTs） increases and the increment of the broad-leaved deciduous forest is the most obvious （5.05 g C m-2 yr-1 ）. During the studied period, the annual NPP of M-SDGVM over China increases, with significant fluctuations, at an average rate of 0.0164 Gt C yr-1 . Regulated by annual temperature and precipitation, the interannual variation of the total NPP shows more significant correlation with temperature （relativity and probability are R= 0.61, P = 0.00403） than precipitation （R = 0.40, P = 0.08352）. CO 2 fertilization may play a key role in the increase of terrestrial ecosystem NPP over continental China, and CO 2 stimulation increases with CO 2 concentrations, and also with the climate variability of the 1980s and 1990s.展开更多
植被碳储量对生态系统碳平衡具有重要调节作用,对植被碳储量进行模拟并分析其对气候变化的响应是全球陆地生态系统碳循环和气候变化研究的重要内容。基于全球植被动态模型模拟的全球植被碳储量,分析植被碳储量在1901年-2000年间的时空...植被碳储量对生态系统碳平衡具有重要调节作用,对植被碳储量进行模拟并分析其对气候变化的响应是全球陆地生态系统碳循环和气候变化研究的重要内容。基于全球植被动态模型模拟的全球植被碳储量,分析植被碳储量在1901年-2000年间的时空变化趋势,及其与气温和降水的时空关系。将LPJ-DGVM(Lund-Potsdam-Jena Dynamic Global Vegetation Model)模型对植被碳储量的模拟结果与国际上被广泛接受的其他研究结果进行了对比后得出,该模型对植被碳储量具有较好的模拟能力。对植被碳储量的模拟结果表明:全球过去100年的植被碳储量在整体上呈增加趋势,增加率为0.0016kgC/(m2a),通过分段线性回归方法得出植被碳储量时间变化趋势存在显著的转折点,20世纪50年代初以前,植被碳储量具有下降趋势,线性斜率为-0.0014kgC/(m2a),之后植被碳储量呈现显著的增加趋势,增加率为0.0055kgC/(m2a),是整体增加率的3倍多,因此整体增加率显著低估了近半个世纪以来植被碳储量的实际增加率。在空间栅格尺度上的分析表明,植被碳储量对气候变化的响应具有很大的区域差异,在不同地区,温度和降水的变化对植被碳储量的变化趋势贡献不同,并与各地区植物生长所受的环境条件约束的状况有关。研究结论进一步说明LPJ能够较好的模拟植物生长与气候之间的相关关系、揭示植被碳储量变化规律和特征,另外为了更好地研究气候变化对植被碳储量的影响,下一步需要对LPJ进行改进,增强其对人类活动如土地利用变化和农业灌溉行为等的模拟能力。展开更多
A dynamic global vegetation model （DGVM） coupled with a land surface model （LSM） is generally initialized using a spin-up process to derive a physically-consistent initial condition. Spin-up forcing, which is the ...A dynamic global vegetation model （DGVM） coupled with a land surface model （LSM） is generally initialized using a spin-up process to derive a physically-consistent initial condition. Spin-up forcing, which is the atmospheric forcing used to drive the coupled model to equilibrium solutions in the spin-up process, varies across earlier studies. In the present study, the impact of the spin-up forcing in the initialization stage on the fractional coverages （FCs） of plant functional type （PFT） in the subsequent simulation stage are assessed in seven classic climate regions by a modified Community Land Model’s Dynamic Global Vegetation Model （CLM-DGVM）. Results show that the impact of spin-up forcing is considerable in all regions except the tropical rainforest climate region （TR） and the wet temperate climate region （WM）. In the tropical monsoon climate region （TM）, the TR and TM transition region （TR-TM）, the dry temperate climate region （DM）, the highland climate region （H）, and the boreal forest climate region （BF）, where FCs are affected by climate non-negligibly, the discrepancies in initial FCs, which represent long-term cumulative response of vegetation to different climate anomalies, are large. Moreover, the large discrepancies in initial FCs usually decay slowly because there are trees or shrubs in the five regions. The intrinsic growth timescales of FCs for tree PFTs and shrub PFTs are long, and the variation of FCs of tree PFTs or shrub PFTs can affect that of grass PFTs.展开更多
利用1971—2006年环杭州湾地区25个气象站的降水、温度和云量资料及全球CO2年平均体积分数资料,采用LPJ全球动态植被模式(Lund-Potsdam-Jena Dynamic Global Vegetation Model),通过模拟环杭州湾地区的植被年净初级生产力(Annual Net Pr...利用1971—2006年环杭州湾地区25个气象站的降水、温度和云量资料及全球CO2年平均体积分数资料,采用LPJ全球动态植被模式(Lund-Potsdam-Jena Dynamic Global Vegetation Model),通过模拟环杭州湾地区的植被年净初级生产力(Annual Net Primary Productivity,ANPP),分析了该地区ANPP的变化特征,并探讨了植被ANPP变化的可能原因。结果表明:1)就环杭州湾地区,36a间植被ANPP均表现出不同程度的增加,尤其以嘉兴市北部、绍兴市东部较明显;全区平均增加速率为1.5243g·m-2·a-2;2)通过多元线性回归分析发现,环杭州湾地区平均云量与植被ANPP的关系最为密切,偏相关系数为-0.5175,而温度、降水与植被ANPP的关系不明显;同时,植被ANPP对气候变化的响应存在一定的地域性差异;3)在全区平均情况下,36a间由温度下降、降水增加、云量减小、CO2体积分数升高引起的植被ANPP变化趋势分别为-0.0813、-0.0171、0.7601、0.8673g·m-2·a-2,其对应的贡献率分别为-5.18%、-1.09%、48.38%、55.21%。由此可见,该地区植被ANPP变化的主要强迫因子是CO2体积分数和云量,而降水变化对植被ANNP的变化作用不大。展开更多
In Dynamic Global Vegetation Models （DGVMs）, the establishment of woody vegetation refers to flowering, fertiliza- tion, seed production, germination, and the growth of tree seedlings. It determines not only the pop...In Dynamic Global Vegetation Models （DGVMs）, the establishment of woody vegetation refers to flowering, fertiliza- tion, seed production, germination, and the growth of tree seedlings. It determines not only the population densities but also other important ecosystem structural variables. In current DGVMs, establishments of woody plant functional types （PFTs） are assumed to be either the same in the same grid cell, or largely stochastic. We investigated the uncertainties in the competition of establishment among coexisting woody PFTs from three aspects： the dependence of PFT establishments on vegetation states; background establishment; and relative establishment potentials of different PFTs. Sensitivity experi- ments showed that the dependence of establishment rate on the fractional coverage of a PFT favored the dominant PFT by increasing its share in establishment. While a small background establishment rate had little impact on equilibrium states of the ecosystem, it did change the timescale required for the establishment of alien species in pre-existing forest due to their disadvantage in seed competition during the early stage of invasion. Meanwhile, establishment purely fiom background （the scheme commonly used in current DGVMs） led to inconsistent behavior in response to the change in PFT specification （e.g., number of PFTs and their specification）. Furthermore, the results also indicated that trade-off between irtdividual growth and reproduction/colonization has significant influences on the competition of establishment. Hence, further development of es- tablishment parameterization in DGVMs is essential in reducing the uncertainties in simulations of both ecosystem structures and successions.展开更多
基金supported by Chinese Academy of Sciences (KZCX2-YW-219, 100 Tal-ents Program)Ministry of Science and Technology of China (2009CB421406)
文摘The capability of an improved Dynamic Global Vegetation Model （DGVM） in reproducing the impact of climate on the terrestrial ecosystem is evaluated. The new model incorporates the Community Land Model- DGVM （CLM3.0-DGVM） with a submodel for temperate and boreal shrubs, as well as other revisions such as the ＂two-leaf＂ scheme for photosynthesis and the definition of fractional coverage of plant functional types （PFTs）. Results show that the revised model may correctly reproduce the global distribution of temperate and boreal shrubs, and improves the model performance with more realistic distribution of di？erent vege- tation types. The revised model also correctly reproduces the zonal distributions of vegetation types. In reproducing the dependence of the vegetation distribution on climate conditions, the model shows that the dominant regions for trees, grasses, shrubs, and bare soil are clearly separated by a climate index derived from mean annual precipitation and temperature, in good agreement with the CLM4 surface data. The dominant plant functional type mapping to a two dimensional parameter space of mean annual temperature and precipitation also qualitatively agrees with the results from observations and theoretical ecology studies.
基金supported by the Chinese Academy of Sciences Strategic Priority Research Program (Grant No. XDA05110103)the State Key Project for Basic Research Program of China (Grant No. 2010CB951801)
文摘ABSTRACT The lAP Dynamic Global Vegetation Model （IAP-DGVM） has been developed to simulate the distribution and structure of global vegetation within the framework of Earth System Models. It incorporates our group＇s recent developments of major model components such as the shrub sub-model, establishment and competition parameterization schemes, and a process-based fire parameterization of intermediate complexity. The model has 12 plant functional types, including seven tree, two shrub, and three grass types, plus bare soil. Different PFTs are allowed to coexist within a grid cell, and their state variables are updated by various governing equations describing vegetation processes from fine-scale biogeophysics and biogeochemistry, to individual and population dynamics, to large-scale biogeography. Environmental disturbance due to fire not only affects regional vegetation competition, but also influences atmospheric chemistry and aerosol emissions. Simulations under observed atmospheric conditions showed that the model can correctly reproduce the global distribution of trees, shrubs, grasses, and bare soil. The simulated global dominant vegetation types reproduce the transition from forest to grassland （savanna） in the tropical region, and from forest to shrubland in the boreal region, but overestimate the region of temperate forest.
基金supported by the National Major Research High Performance Computing Program of China(Grant No.2016YFB02008)the National Natural Science Foundation of China(Grant Number 41705070)supported by the National Natural Science Foundation of China(Grant Numbers 41475099 and 41305096)
文摘In the past several decades, dynamic global vegetation models（DGVMs） have been the most widely used and appropriate tool at the global scale to investigate vegetation-climate interactions. At the Institute of Atmospheric Physics, a new version of DGVM（IAP-DGVM） has been developed and coupled to the Common Land Model（CoLM） within the framework of the Chinese Academy of Sciences＇ Earth System Model（CAS-ESM）. This work reports the performance of IAP-DGVM through comparisons with that of the default DGVM of CoLM（CoLM-DGVM） and observations. With respect to CoLMDGVM, IAP-DGVM simulated fewer tropical trees, more ＂needleleaf evergreen boreal tree＂ and ＂broadleaf deciduous boreal shrub＂, and a better representation of grasses. These contributed to a more realistic vegetation distribution in IAP-DGVM,including spatial patterns, total areas, and compositions. Moreover, IAP-DGVM also produced more accurate carbon fluxes than CoLM-DGVM when compared with observational estimates. Gross primary productivity and net primary production in IAP-DGVM were in better agreement with observations than those of CoLM-DGVM, and the tropical pattern of fire carbon emissions in IAP-DGVM was much more consistent with the observation than that in CoLM-DGVM. The leaf area index simulated by IAP-DGVM was closer to the observation than that of CoLM-DGVM; however, both simulated values about twice as large as in the observation. This evaluation provides valuable information for the application of CAS-ESM, as well as for other model communities in terms of a comparative benchmark.
基金supported by the China Meteorological Administration through Grant GYHY (QX) 2007-25the 973 project under Grant 2005CB321703+1 种基金the Fund for Inno-vative Research Groups under Grant No. 40821092the National Natural Science Foundation of China (NSFC) project under Grant Nos. 40225013 and 40730106
文摘Using the regional terrestrial Net Primary Production （NPP） from different observations and models over China, we validated the NPP simulations and explored the relationship between NPP and climate variation at interannual and decadal scales in the Modified Sheffield Dynamic Global Vegetation Model （M-SDGVM） during 1981–2000. M-SDGVM shows agreement with the NPP data from 743 sites under the Global Primary Production Data Initiative （GPPDI）. The spatial and the zonal averaged NPP of M-SDGVM agree well with different historic datasets and are closest to the IGBP NPP. Compared to the 1980s, NPP in the 1990s increases in most of China with a high degree of spatial heterogeneity. The multi-year mean NPP of forest types is reasonably modeled （above 500 g C m-2 yr-1 ） while that of C 3 path of photosynthesis （C 3 ） grasslands is underestimated. The NPP of 7 M-SDGVM main plant functional types （PFTs） increases and the increment of the broad-leaved deciduous forest is the most obvious （5.05 g C m-2 yr-1 ）. During the studied period, the annual NPP of M-SDGVM over China increases, with significant fluctuations, at an average rate of 0.0164 Gt C yr-1 . Regulated by annual temperature and precipitation, the interannual variation of the total NPP shows more significant correlation with temperature （relativity and probability are R= 0.61, P = 0.00403） than precipitation （R = 0.40, P = 0.08352）. CO 2 fertilization may play a key role in the increase of terrestrial ecosystem NPP over continental China, and CO 2 stimulation increases with CO 2 concentrations, and also with the climate variability of the 1980s and 1990s.
文摘植被碳储量对生态系统碳平衡具有重要调节作用,对植被碳储量进行模拟并分析其对气候变化的响应是全球陆地生态系统碳循环和气候变化研究的重要内容。基于全球植被动态模型模拟的全球植被碳储量,分析植被碳储量在1901年-2000年间的时空变化趋势,及其与气温和降水的时空关系。将LPJ-DGVM(Lund-Potsdam-Jena Dynamic Global Vegetation Model)模型对植被碳储量的模拟结果与国际上被广泛接受的其他研究结果进行了对比后得出,该模型对植被碳储量具有较好的模拟能力。对植被碳储量的模拟结果表明:全球过去100年的植被碳储量在整体上呈增加趋势,增加率为0.0016kgC/(m2a),通过分段线性回归方法得出植被碳储量时间变化趋势存在显著的转折点,20世纪50年代初以前,植被碳储量具有下降趋势,线性斜率为-0.0014kgC/(m2a),之后植被碳储量呈现显著的增加趋势,增加率为0.0055kgC/(m2a),是整体增加率的3倍多,因此整体增加率显著低估了近半个世纪以来植被碳储量的实际增加率。在空间栅格尺度上的分析表明,植被碳储量对气候变化的响应具有很大的区域差异,在不同地区,温度和降水的变化对植被碳储量的变化趋势贡献不同,并与各地区植物生长所受的环境条件约束的状况有关。研究结论进一步说明LPJ能够较好的模拟植物生长与气候之间的相关关系、揭示植被碳储量变化规律和特征,另外为了更好地研究气候变化对植被碳储量的影响,下一步需要对LPJ进行改进,增强其对人类活动如土地利用变化和农业灌溉行为等的模拟能力。
基金supported by the Chinese Academy of Sciences under Grant No.KZCX2-YW-219State Key Project for Basic Research Program of China(973)under Grant No.2010CB951801Key Program of National Natural Science Foundation under Grant No.40830103
文摘A dynamic global vegetation model （DGVM） coupled with a land surface model （LSM） is generally initialized using a spin-up process to derive a physically-consistent initial condition. Spin-up forcing, which is the atmospheric forcing used to drive the coupled model to equilibrium solutions in the spin-up process, varies across earlier studies. In the present study, the impact of the spin-up forcing in the initialization stage on the fractional coverages （FCs） of plant functional type （PFT） in the subsequent simulation stage are assessed in seven classic climate regions by a modified Community Land Model’s Dynamic Global Vegetation Model （CLM-DGVM）. Results show that the impact of spin-up forcing is considerable in all regions except the tropical rainforest climate region （TR） and the wet temperate climate region （WM）. In the tropical monsoon climate region （TM）, the TR and TM transition region （TR-TM）, the dry temperate climate region （DM）, the highland climate region （H）, and the boreal forest climate region （BF）, where FCs are affected by climate non-negligibly, the discrepancies in initial FCs, which represent long-term cumulative response of vegetation to different climate anomalies, are large. Moreover, the large discrepancies in initial FCs usually decay slowly because there are trees or shrubs in the five regions. The intrinsic growth timescales of FCs for tree PFTs and shrub PFTs are long, and the variation of FCs of tree PFTs or shrub PFTs can affect that of grass PFTs.
文摘利用1971—2006年环杭州湾地区25个气象站的降水、温度和云量资料及全球CO2年平均体积分数资料,采用LPJ全球动态植被模式(Lund-Potsdam-Jena Dynamic Global Vegetation Model),通过模拟环杭州湾地区的植被年净初级生产力(Annual Net Primary Productivity,ANPP),分析了该地区ANPP的变化特征,并探讨了植被ANPP变化的可能原因。结果表明:1)就环杭州湾地区,36a间植被ANPP均表现出不同程度的增加,尤其以嘉兴市北部、绍兴市东部较明显;全区平均增加速率为1.5243g·m-2·a-2;2)通过多元线性回归分析发现,环杭州湾地区平均云量与植被ANPP的关系最为密切,偏相关系数为-0.5175,而温度、降水与植被ANPP的关系不明显;同时,植被ANPP对气候变化的响应存在一定的地域性差异;3)在全区平均情况下,36a间由温度下降、降水增加、云量减小、CO2体积分数升高引起的植被ANPP变化趋势分别为-0.0813、-0.0171、0.7601、0.8673g·m-2·a-2,其对应的贡献率分别为-5.18%、-1.09%、48.38%、55.21%。由此可见,该地区植被ANPP变化的主要强迫因子是CO2体积分数和云量,而降水变化对植被ANNP的变化作用不大。
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA05110103)the State Key Project for Basic Research Program of China(Grant No.2010CB951801)the National High Technology Research and Development Program of China(863 Program)(Grant No.2009AA122105)
文摘In Dynamic Global Vegetation Models （DGVMs）, the establishment of woody vegetation refers to flowering, fertiliza- tion, seed production, germination, and the growth of tree seedlings. It determines not only the population densities but also other important ecosystem structural variables. In current DGVMs, establishments of woody plant functional types （PFTs） are assumed to be either the same in the same grid cell, or largely stochastic. We investigated the uncertainties in the competition of establishment among coexisting woody PFTs from three aspects： the dependence of PFT establishments on vegetation states; background establishment; and relative establishment potentials of different PFTs. Sensitivity experi- ments showed that the dependence of establishment rate on the fractional coverage of a PFT favored the dominant PFT by increasing its share in establishment. While a small background establishment rate had little impact on equilibrium states of the ecosystem, it did change the timescale required for the establishment of alien species in pre-existing forest due to their disadvantage in seed competition during the early stage of invasion. Meanwhile, establishment purely fiom background （the scheme commonly used in current DGVMs） led to inconsistent behavior in response to the change in PFT specification （e.g., number of PFTs and their specification）. Furthermore, the results also indicated that trade-off between irtdividual growth and reproduction/colonization has significant influences on the competition of establishment. Hence, further development of es- tablishment parameterization in DGVMs is essential in reducing the uncertainties in simulations of both ecosystem structures and successions.
