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Response of ecosystem Respiration to Experimental Warming and Clipping at Daily Time Scale in an Alpine Meadow of Tibet

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Journal of Mountain Science 2013年第3期10卷 455-463页

作者： FU Gang SHEN Zhen-xi ZHANG Xian-zhou YU Cheng-qun ZHOU Yu-ting LI Yun-long YANG Peng-wan Lhasa Plateau ecosystem research Station Key Laboratory of Ecosystem Network Observation and ModelingInstitute of Geographic Sciences and Natural Resources ResearchChinese Academy of Sciences University of chinese Academy of Sciences

The alpine meadow, as one of the typical vegetation types on the Tibetan Plateau, is one of the most sensitive terrestrial ecosystems to climate warming. However, how climate warming affects the carbon cycling of the alpine meadow on the Tibetan Plateau is not very dear. A field experiment under controlled experimental warming and clipping conditions was conducted in an alpine meadow on the Northern Tibetan Plateau since July 2008. Open top chambers （0TCs） were used to simulate climate warming. The main objective of this study was to examine the responses of ecosystem respiration （Reco） and its temperature sensitivity to experimental warming and clipping at daily time scale. Therefore, we measured Reco once or twice a month from July to September in 2010, from June to September in 2011 and from August to September in 2012. Air temperature dominated daily variation of Reco whether or not experimental warming and clipping were present. Air temperature was exponentially correlated with Reco and it could significantly explain 58-96% variation of Redo at daily time scale. Experimental warming and clipping decreased daily mean Reco by 5.8-37.7% and -11.9-23.0%, respectively, although not all these changes were significant. Experimental warming tended to decrease the temperature sensitivity of Reco, whereas clipping tended to increase the temperature sensitivity of Reco at daily time scale. Our findings suggest that Reco wasmainly controlled by air temperature and may acclimate to climate warming due to its lower temperature sensitivity under experimental warming at daily time scale.

关键词： Acclimation Air temperature Open topchamber Temperature sensitivity Respirationquotient ( Q10)

Clipping Alters the Response of Biomass Production to Experimental Warming: A Case Study in an Alpine Meadow on the Tibetan Plateau, China

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Journal of Mountain Science 2015年第4期12卷 935-942页

作者： FU Gang SUN Wei YU Cheng-Qun ZHANG Xian-Zhou SHEN Zhen-Xi LI Yun-Long YANG Peng-Wan ZHOU Nan Lhasa Plateau ecosystem research Station Key Laboratory of Ecosystem Network Observation and ModelingInstitute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences University of chinese Academy of Sciences

Predicting how human activity will influence the response of alpine grasslands to future warming has many *** this study, a field experiment with controlled warming and clipping was conducted in an alpine meadow at three elevations（4313 m, 4513 m and 4693 m） in Northern Tibet to test the hypothesis that clipping would alter warming effect on biomass *** top chambers（OTCs） were used to increase temperature since July,2008 and the OTCs increased air temperature by approximately 0.9o C ~ 1.8o C during the growing *** was conducted three times one year during growing season and the aboveground parts of all live plants were clipped to approximately 0.01 m in height using scissors since *** primary production（GPP） was calculated from the Moderate-Resolution Imaging Spectroradiometer GPP algorithm and aboveground plant production was estimated using the surface-measured normalized difference vegetation index in *** decreased the GPP, aboveground biomass（AGB） and aboveground net primary production（ANPP） at all three elevations when clipping was not *** contrast, warming increased AGB at all three elevations, GPP at the two lower elevations and ANPP at the two higher elevations when clipping was *** findings show that clipping reduced the negative effect of warming on GPP, AGB and ANPP, suggesting that clipping may reduce the effect of climate warming on GPP, AGB and ANPP in alpine meadows on the Tibetan Plateau, and therefore, may be a viable strategy for mitigating the effects of climate change on grazing and animal husbandry on the Tibetan Plateau.

关键词： Clipping Gross primary production Open top chamber Warming Alpine Meadow Tibetan Plateau

The Altitudinal Belts of Subalpine Virgin Forest on *** Simulated by a Succession Model

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Journal of Mountain Science 2014年第6期11卷 1560-1570页

作者： CHENG Gen-wei SUN Jian SHA Yu-kun FAN Ji-hui Key Laboratory of Mountain Surface Process and Ecological Regulation Institute of Mountain Hazard and EnvironmentChinese Academy of Sciences Synthesis research Centre of chinese ecosystem research network Key Laboratory of Ecosystem Network Observation and Modelling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences University of chinese Academy of Sciences

How to accurately simulate the distribution of forest species based upon their biological attributes has been a traditional biogeographical *** gap models are very useful tools for examining the dynamics of forest succession and revealing the species structure of *** the present study,the GFSM(Gongga Forest Succession Model) was developed and applied to simulate the distribution,composition and succession process of forests in 100 m elevation *** results indicate that the simulated results of the tree species,quantities of the different types of trees,tree age and differences in DBH(diameter at breast height) composition were in line with the actual situation from 1400 to 3700 MASL(meters above sea level) on the eastern slope of ***,the dominant species in the simulated results were the same as those in the surveyed ***,the GFSM model can best simulate the features of forest dynamics and structure in the natural conditions of *** work provides a new approach to studying the structure and distribution characteristics of mountain ecosystems in varied ***,the results of this study suggest that the biogeochemistry mechanism model should be combined with the forestsuccession model to facilitate the ecological model in simulating the physical and chemical processes involved.

关键词： Subalpine forests Altitudinal belts Succession processes Forest gap model

Characteristics of dew events in an arid artificial oasis cropland and a sub-humid cropland in China

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Journal of Arid Land 2016年第3期8卷 399-408页

作者： MENG Yao WEN Xuefa Key Laboratory of ecosystem network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences

Dew is an important source of water which significantly influences the physiological status of vegetation and the microclimate environment. For quantifying the characteristics of dew events and analyzing the underlying mechanism of dew formation in different ecosystems, we measured, based on the flux-profile method, the amount, frequency and duration of dew events in two croplands, an arid artificial oasis cropland in Zhangye, Gansu province and a sub-humid cropland in Luancheng, Hebei province in China. The results showed that dew events were observed in a total of 69 days in Zhangye, which accounted for 59% of the growing season（from 28 May to 21 September, 2012）, while 128 days in Luancheng, which accounted for 79% of the growing season（from 5 April to 13 September, 2008）. The frequencies of dew events were 2.8 and 2.4 times of those of precipitation in Zhangye and Luancheng, respectively. In addition, the dew amount reached up to 9.9 and 20.2 mm in Zhangye and Luancheng, which accounted for 9.5% and 4.1% of precipitation, respectively. The average amount of dew was 0.14 and 0.16 mm/night in Zhangye and Luancheng, respectively and the duration of dew events ranged from 0.5 to 12.0 h in the two study sites. Dew amounts were associated with the gradient of atmospheric water vapor concentration and dew duration（P＆lt;0.001） in both the two sites. The result implies that dew events play a more important role in crop growth in arid areas in comparison to sub-humid areas considering the dew occurrence frequency and the amount per night.

关键词： dew amount frequency of dew duration of dew flux-profile

Effects of livestock exclusion and climate change on aboveground biomass accumulation in alpine pastures across the Northern Tibetan Plateau

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chinese Science Bulletin 2014年第32期59卷 4332-4340页

作者： Jianshuang Wu Xianzhou Zhang Zhenxi Shen Peili Shi Chengqun Yu Baoxiong Chen Lhasa Plateau ecosystem research Station Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences University of chinese Academy of Sciences

To better understand the ecological and economic benefits of short-term grazing exclusion on the aboveground net primary productivity(ANPP)of alpine pastures,we conducted annual multi-site transect surveys in the summers from 2009 to 2011 and calculated the aboveground biomass discrepancy(ABD)between grazed and ungrazed pastures at plant community and economic group levels for three zonal alpine grassland types—meadow,steppe,and desert-steppe—across the northern Tibetan *** results indicated that aboveground biomass(AGB)significantly differed among grassland types and declined northwesterly from 64.07 to11.44 g m-2with decreasing precipitation and increasing *** mean ABD exhibited considerable community dependency,with meadow(12.47 g m-2)[steppe(6.91 g m-2)[desert steppe(2.54 g m-2),and it declined from 25.42 to 1.29 g m-2with decreasing precipitation and increasing temperature.‘Good forage’,*** and sedges,benefited most from grazing exclusion,followed by edible *** longer grazing exclusion durations(GEDs),the aboveground biomass of poisonous locoweeds initially decreased and then increased compared with the adjacent grazed *** the nested analysis of co-variances with a general linear model,growing season precipitation(GSP;from May to September)accounted for 52.67%ofthe observed variation in AGB,followed by AGT(9.77%)and pasture management systems(PMSs;grazing or grazing-excluded,5.31%).The variation in ABD was explained primarily by AGT(16.52%),GED(20.25%),and the interaction of AGT 9 GED(19.58%).Our results confirm that precipitation is the primary factor controlling the ANPP of alpine grasslands on the Northern Tibetan Plateau and that the ecological benefits arising from grazing exclusion are also partly dependent on grassland type and exclusion ***,spatial and temporal variations in growing season precipitation and plant functional traits or economic group composition should be jointly considered when devel

关键词：地上生物量藏北高原生物量积累牧场高山气候变化荒漠草原牲畜

Effects of climate and forest age on the ecosystem carbon exchange of afforestation

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Journal of Forestry research 2020年第2期31卷 365-374页

作者： Zhi Chen Guirui Yu Qiufeng Wang Synthesis research Center of chinese ecosystem research network and Key Laboratory of Ecosystem Network Observation and ModelingInstitute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101People’s Republic of China College of Resources and Environment University of Chinese Academy of SciencesBeijing 100049People’s Republic of China

Afforestation is believed to be an effective practice to reduce global warming by sequestering large amounts of carbon in plant biomass and ***,the factors that determine the rate of carbon sequestration with afforestation are still poorly *** analyzed ecosystem carbon exchange after afforestation based on eddy covariance measurements with the aim to identify factors responsible for the rate of carbon exchange following *** results indicated that afforestation in the tropical/subtropical and temperate climate zones had greater capacities for carbon sequestration than those in boreal *** ecosystem production(NEP),gross primary production(GPP)and ecosystem respiration(RE)varied greatly with age groups over ***,NEP was initially less than zero in the\10 year group and then increased to its peak in the 10-20 year *** of varied previous land use types and planting of diverse tree species did not result in different carbon *** general linear model showed that climate zone and age of afforestation were the dominant factors influencing carbon *** factors jointly controlled 51%,61%and 63%of the variation in NEP,GPP and RE,*** to the strong regulation of climate on GPP and RE,NEP showed greater sensitivity to the age of *** results increase our understanding of the variation in ecosystem carbon exchange of afforestation and suggest that afforestation in subtropical and temperate areas after 20 years would yield greater carbon sink benefits than would afforestation of boreal regions.

关键词： Afforestation Carbon sequestration Eddy covariance Climate Age

Nitrogen additions inhibit nitrification in acidic soils in a subtropical pine plantation: effects of soil pH and compositional shifts in microbial groups

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Journal of Forestry research 2019年第2期30卷 669-678页

作者： Liang Kou Xinyu Zhang Huimin Wang Hao Yang Wei Zhao Shenggong Li Key Laboratory of ecosystem network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences University of chinese Academy of Sciences Jiangxi Provincial Key Laboratory of ecosystem Processes and Information

Plantation forests play a pivotal role in carbon sequestration in terrestrial ecosystems, but enhanced nitrogen(N) deposition in these forests may affect plantation productivity by altering soil N cycling. Hence,understanding how simulated N deposition affects the rate and direction of soil N transformation is critically important in predicting responses of plantation productivity in the context of N loading. This study reports the effects of N addition rate(0, 40, and 120 kg N ha^(-1) a^(-1)) and form(NH_4Cl vs. NaNO_3) on net N mineralization and nitrification estimated by in situ soil core incubation and on-soil microbial biomass determined by the phospholipid fatty acid(PLFA) method in a subtropical pine plantation. N additions had no influences on net N mineralization throughout the year. Net nitrification rate was significantly reduced by additions of both NH_4Cl(71.5) and NaNO_3(47.1%) during the active growing season, with the stronger inhibitory effect at high N rates. Soil pH was markedly decreased by 0.16 units by NH_4Cl additions. N inputs significantly decreased the ratio of fungal-to-bacterial PLFAs on average by 0.28(49.1%) in November. Under NH_4Cl additions, nitrification was positively related with fungal biomass and soil pH. Under NaNO_3 additions,nitrification was positively related with all microbial groups except for bacterial biomass. We conclude that simulated N deposition inhibited net nitrification in the acidic soils of a subtropical plantation forest in China,primarily due to accelerated soil acidification and compositional shifts in microbial functional groups. These findings may facilitate a better mechanistic understanding of soil N cycling in the context of N loading.

关键词： Acidification Atmospheric nitrogen deposition Microbial functional group Nitrification Soil nitrogen transformation

The Limiting Effect of Deep Soil Water on Evapotranspiration of a Subtropical Coniferous Plantation Subjected to Seasonal Drought

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Advances in Atmospheric Sciences 2014年第2期31卷 385-395页

作者： TANG Yakun WEN Xuefa SUN Xiaomin ZHANG Xinyu WANG Huimin Key Laboratory of ecosystem network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences University of chinese Academy of Sciences

Seasonal drought is a common occurrence in humid *** year 2003 was the driest year during the period 1985-2011 in southeastern *** objective of this study was to elucidate the impact of the exceptional drought in 2003,compared with eddy flux measurements during 2004-11,on the dynamics of evapotranspiration （ET） and related factors,as well as their underlying mechanisms,in a subtropical coniferous plantation in southeastern *** was found that daily ET decreased from 5.34 to 1.84 mm during the intensive drought period and recovered to 4.80 mm during the subsquent recovering drought *** analysis indicated that ET was mainly determined by canopy conductance and deep soil water content （50 cm） during the intensive drought and recovering drought periods,*** canopy conductance offset the positive effect of air vapor pressure deficit on ET when suffering drought stress,while the canopy conductance enhanced the positive effect of air temperature on ET during the late growing *** the fine roots of this plantation are mainly distributed in shallow soil,and the soil water in the upper 40 cm did not satisfy the demand for ET,stomatal closure and defoliation were evident as physiological responses to drought stress.

关键词： ChinaFLUX evapotranspiration seasonal drought subtropical coniferous plantation

Baseflow Characteristics in Alpine Rivers-a Multicatchment Analysis in Northwest China

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Journal of Mountain Science 2015年第3期12卷 614-625页

作者： GAN Rong SUN Lin LUO Yi Key Laboratory of ecosystem network Observation and Modeling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of Sciences University of chinese Academy of Sciences

As a component of streamflow, baseflow is critical for regulating seasonal distribution of river fows and stabilizing water supplies. Water resources in the arid area of Northwest China are mainly from multiple catchments in the alpine that could be influenced by varieties of climatic, land cover, soil and geological factors. While numerous studies have been done on streamflow, systematic analysis of baseflow in the alpine river systems is scare. Based on historical daily streamflow data and the automated digital filter method of baseflow separation, this study investigated characteristics of hydrographs of overland flow, streamflow and baseflowof river systems fed by rainfall, snowmelt, glacier melt or mixtures of these. This study also calculated the recession constants and baseflow indices of 65 river systems. While the recession constant was ***34- o.o728 with a mean of o.o18, the baseflow index was 0.27-0.79 with a mean of 0.57. Further, Spearman＇s correlation analysis showed that the baseflow index was significantly correlated with catchment climatic factors （e.g., precipitation and temperature）, topographic factors （e.g., elevation and slope） and aquifer properties represented by the recession constant. Multiple regression analysis indicated that the factors explained 65% of the variability of baseflow index in the studv area.

关键词： Baseflow index Recession constant Snowmelt Glacier melt Streamflow