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Dominant species of mid-elevation grasslands of the uKhahlamba-Drakensberg Park are predicted to be largely immune to climate change

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山地科学学报(英文) 2023年第9期20卷 2468-2486页

作者： Debbie JEWITT Craig D.MORRIS Tim G.O’CONNOR Michelle J.TEDDER Ezemvelo KZN Wildlife Scientific ServicesPO Box 13053Cascades 3202South Africa School of Animal Plant and Environmental SciencesUniversity of the WitwatersrandJohannesburgPrivate Bag X3WITS 2050South Africa Agricultural Research Council-Animal Production(ARC-AP) ℅School of Life Sciences University of KwaZulu-NatalPrivate Bag X01Scottsville 3209PietermaritzburgSouth Africa School of Life Sciences University of KwaZulu-NatalPrivate Bag X01Scottsville 3209PietermaritzburgSouth Africa

Anticipating global change impact on natural vegetation,especially in poorly researched systems,requires an understanding of the environmental factors that most strongly influence the organisation of plant communities at different scales.The environmental relations of plant communities in the Drakensberg mountains of South Africa remain poorly researched.This study investigated the influence of selected environmental determinants on the dominant species of plant community organisation in this area.In order to provide an overview of the influence of the environment on botanical composition and plant diversity,this study,conducted as four discrete exercises,investigated the interplay of altitude,aspect and slope on the abundance of selected species,and to examine the influence of latitude,geological substrate and local topography on species composition.Plant diversity showed no pattern of response to investigated environmental variables.Species composition was related to temperature and solarradiation variables.High altitude sites facing east were distinct for non-graminoid species.Altitude and latitude exerted a pronounced effect on species composition,confounded by longitude and precipitation gradients.Geological substrate,in concert with slope steepness and orientation,influenced composition,restricting the abundance but not distribution of some grasses.Highly individualistic responses were found for C_3,C_4,and non-graminoid species in relation to altitude,slope and aspect.Slope and aspect mediate the effects of altitude and hence temperature for some species.This study has demonstrated the complexity of drivers influencing species and compositional distribution in the Drakensberg and permits a preliminary consideration of potential changes in the composition and dominance structure of mid-elevation grasslands in response to climate change.The dominant grass species were widespread across environmental gradients,occupying currently warm,cool,moist and dry habitats.Hence,we predict that these midelevation C_4 gr

关键词： Drakensberg Environmental gradients grasslands Mountain biodiversity Vegetation

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Elevated and atmospheric-level methane consumption by soil methanotrophs of three grasslands in China

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Grassland Research 2023年第2期2卷 85-96页

作者： Yufang Wang Yuanfeng Cai Fujiang Hou Saman Bowatte Zhongjun Jia State Key Laboratory of Herbage Improvement and Grassland Agroecosystems Key Laboratory of Grassland Livestock Industry InnovationMinistry of Agriculture and Rural AffairsCollege of Pastoral Agriculture Science and TechnologyLanzhou UniversityLanzhouGansu ProvinceChina State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjingJiangsu ProvinceChina AgResearch Limited Grasslands Research CentrePalmerston NorthNew Zealand Northeast Institute of Geography and Agroecology Chinese Academy of SciencesChangchunJilin ProvinceChina

Background:Methane(CH4)oxidation driven by soil aerobic methanotrophs demonstrates the capacity of grassland as a CH4 sink.Methods:In this study,we compared the oxidation characteristics of atmospheric-level and elevated concentration(10%)CH4 in a typical grassland(steppe)on the Loess Plateau,an alpine meadow(meadow)on the Qinghai-Tibet Plateau,and an inland arid-area artificial grassland(pasture)in northwest China and investigated the communities of active methanotrophs and their contribution to CH4 oxidation using DNA-based stable-isotope probing and Illumina Miseq sequencing.Results:The results showed that the oxidation of atmospheric CH4 only occurred in steppe and meadow soils where the USCγgroup of methanotrophs was numerically dominant in the methanotroph community.Pasture soils,with their very low relative abundance of USCγ,did not show atmospheric CH4 oxidation.However,a DNA-stable isotope probing experiment with 10%CH4 indicated that conventional CH4 oxidizers(Methylocaldum and Methylocystis)rather than USCγcommunities assimilated significant amounts of 13CH4 for growth.Conclusions:The CH4 oxidation mechanisms in the three experimental grassland soils varied significantly.The USCγgroup may be obligate oligotrophic microorganisms or their growth requires specific unknown conditions.

关键词： grasslands methane oxidation methanotrophs uncultivated methanotrophs USCγ

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Deciphering impacts of climate extremes on Tibetan grasslands in the last fifteen years

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Science Bulletin 2019年第7期64卷 446-454页

作者： Dan Liu Tao Wang Tao Yang Zhengjie Yan Yongwen Liu Yutong Zhao Shilong Piao Key Laboratory of Alpine Ecology Institute of Tibetan Plateau Research Chinese Academy of Sciences Center for Excellence in Tibetan Plateau Earth Sciences Chinese Academy of Sciences School of Life Sciences Lanzhou University College of Urban and Environmental Sciences and Sino-French Institute for Earth System Science Peking University

Climate extremes have emerged as a crucial driver of changes in terrestrial ecosystems. The Tibetan Plateau, facing a rapid climate change, tends to favor climate extremes. But we lack a clear understanding of the impacts of such extremes on alpine grasslands. Here we show that extreme events(drought,extreme wet, extreme cold and extreme hot) occurred at a frequency of 0.67–4 months decade^(-1) during2001–2015, with extreme precipitation predominantly occurring in June-to-August and extreme temperatures in May. Drought and extreme wet cause opposite and asymmetric effects on grassland growth,with drought-induced reductions greater than increases due to extreme wet. Grassland responses to extreme temperatures, which predominantly occur in May, show a dipole-like spatial pattern, with extreme hot(cold) events enhanced(reduced) growth in the eastern plateau but slightly reduced(enhanced) growth in the western plateau. These opposite responses to extreme temperatures over the eastern plateau are explained by the possibility that the occurrence of extreme cold slows the preseason temperature accumulation, delaying the triggering of spring phenology, while extreme hot hastens the accumulation. In the western plateau, in contrast, positive responses to extreme cold are induced by accompanying high precipitation. Furthermore, high extremeness of climate events generally led to a much lower extremeness in growth response, implying that the Tibetan grasslands have a relatively high resistance to climate extremes. The ecosystem models tested could not accurately simulate grassland responses to drought and extreme temperatures, and require re-parameterization before trust can be placed in their output for this region.

关键词： Drought Extreme cold Extreme hot Growth response Alpine grasslands Tibetan Plateau

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Global patterns and climatic drivers of above-and belowground net primary productivity in grasslands

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Science China(Life Sciences) 2021年第5期64卷 739-751页

作者： Yuanfeng Sun Yuanhe Yang Xia Zhao Zhiyao Tang Shaopeng Wang Jingyun Fang Institute of Ecology College of Urban and Environmental Sciencesand Key Laboratory for Earth Surface Processes of the Ministry of EducationPeking UniversityBeijing 100871China State Key Laboratory of Vegetation and Environmental Change Institute of BotanyChinese Academy of SciencesBeijing 100093China

Understanding patterns and determinants of net primary productivity(NPP)in global grasslands is ongoing challenges,especially for belowground NPP(BNPP)and its fraction(fBNPP).By developing a comprehensive field-based dataset,we revealed that,along with gradients of mean annual precipitation,actual evapotranspiration,and aridity,aboveground NPP(ANPP),BNPP,and total NPP(TNPP)exhibited hump-shaped patterns,whereas fBNPPshowed an opposite trend.ANPP and TNPP showed positive correlations with mean annual temperature,but fBNPPwas negatively correlated with it.The relationship between BNPP and climatic factors was considerably weak,indicating that BNPP was relatively stable regardless of the climate conditions.We also observed that the sensitivities of ANPP and BNPP to interannual temperature variability and those of BNPP to interannual precipitation fluctuations exhibited large variations among different study sites,and differed from those at the spatial scale.In contrast,the temporal sensitivities of ANPP to interannual precipitation variability were highly similar across all the individual sites and much smaller than those at the spatial scale.Overall,these results highlight that precipitation,temperature and evapotranspiration all play vital roles in shaping ANPP pattern and its partitioning to belowground and that the patterns of BNPP along climatic gradients do not mirror those of the ANPP.

关键词： net primary productivity productivity partition climate change grasslands precipitation temperature

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Fencing for conservation?--The impacts of fencing on grasslands and the endangered Przewalski's gazelle on the Tibetan Plateau

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Science China(Life Sciences) 2018年第12期61卷 1593-1595页

作者： Lu Zhang Jiazi Liu Dajun Wang Hao Wang Yonglin Wu Zhi Lu Center for Nature and Society School of Life SciencePeking UniversityBeijing 100871China Qinghai Lake Nature Reserve Xining 810008China Department of Wildlife Fisheries and AquacultureMississippi State UniversityMississippi StateMS 39762USA

Dear Editor, grasslands in north-western China support six species of wild antelopes(Jiang et al.,1996).Among those,the Przewalski's gazelle(Procapra przewalskii)is endangered with a most restricted distribution range.This species is only found on grasslands around the Qinghai Lake in the north-eastern corner of the Tibetan Plateau(Jiang et al., 1995).While poaching of gazelles has been largely prevented since 2002,fencing,a measure supported by grassland conservation policies,has posed negative impacts on the gazelles(Zhang et al.,2014).

关键词： Dear Editor grasslands

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Above-and belowground biomass in relation to envi- ronmental factors in temperate grasslands, Inner Mongolia

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Science China(Life Sciences) 2008年第3期51卷 263-270页

作者： MA WenHong1,2, YANG YuanHe1, HE JinSheng1, ZENG Hui1,2 & FANG JingYun1 1 Department of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China 2 School of Environment & Urban Study, Peking University Shenzhen Graduate School, Shenzhen 518055, China Department of Ecology College of Urban and Environmental Sciences Peking University Beijing China School of Environment & Urban Study Peking University Shenzhen Graduate School Shenzhen China

Above- and belowground biomasses of grasslands are important parameters for characterizing re- gional and global carbon cycles in grassland ecosystems. Compared with the relatively detailed in- formation for aboveground biomass (AGB), belowground biomass (BGB) is poorly reported at the re- gional scales. The present study, based on a total of 113 sampling sites in temperate grassland of the Inner Mongolia, investigated regional distribution patterns of AGB, BGB, vertical distribution of roots, and their relationships with environmental factors. AGB and BGB increased from the southwest to the northeast of the study region. The largest biomass occurred in meadow steppe, with mean AGB and BGB of 196.7 and 1385.2 g/m2, respectively; while the lowest biomass occurred in desert steppe, with an AGB of 56.6 g/m2 and a BGB of 301.0 g/m2. In addition, about 47% of root biomass was distributed in the top 10 cm soil. Further statistical analysis indicated that precipitation was the primary determinant factor in shaping these distribution patterns. Vertical distribution of roots was significantly affected by precipitation, while the effects of soil texture and grassland types were weak.

关键词： temperate grasslands aboveground biomass (AGB) belowground biomass (BGB) spatial pattern vertical distribution precipitation

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Ecosystem carbon stocks and their changes in China's grasslands

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Science China(Life Sciences) 2010年第7期53卷 757-765页

作者： Anwar MOHAMMAT Department of Ecology Key Laboratory for Earth Surface Processes of the Ministry of EducationCollege of Urban and Environmental SciencesPeking University

The knowledge of carbon(C) stock and its dynamics is crucial for understanding the role of grassland ecosystems in China's terrestrial C cycle.To date,a comprehensive assessment on C balance in China's grasslands is still lacking.By reviewing published literature,this study aims to evaluate ecosystem C stocks(both vegetation biomass and soil organic C) and their changes in China's grasslands.Our results are summarized as follows:(1) biomass C density(C stock per area) of China's grasslands differed greatly among previous studies,ranging from 215.8 to 348.1 g C m-2 with an average of 300.2 g C m-2.Likewise,soil C density also varied greatly between 8.5 and 15.1 kg C m-2.In total,ecosystem C stock in China's grasslands was estimated at 29.1 Pg C.(2) Both the magnitude and direction of ecosystem C changes in China's grasslands differed greatly among previous studies.According to recent reports,neither biomass nor soil C stock in China's grasslands showed a significant change during the past 20 years,indicating that grassland ecosystems are C neutral.(3) Spatial patterns and temporal dynamics of grassland biomass were closely correlated with precipitation,while changes in soil C stocks exhibited close associations with soil moisture and soil texture.Human activities,such as livestock grazing and fencing could also affect ecosystem C dynamics in China's grasslands.

关键词： alpine grasslands biomass carbon sink climate change soil organic carbon soil texture temperate grasslands

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Biomass carbon stocks and their changes in northern China's grasslands during 1982-2006

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Science China(Life Sciences) 2010年第7期53卷 841-850页

作者： Anwar MOHAMMAT Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences

Grassland covers approximately one-third of the area of China and plays an important role in the global terrestrial carbon(C) cycle.However,little is known about biomass C stocks and dynamics in these grasslands.During 2001-2005,we conducted five consecutive field sampling campaigns to investigate above-and below-ground biomass for northern China's grasslands.Using measurements obtained from 341 sampling sites,together with a NDVI(normalized difference vegetation index) time series dataset over 1982-2006,we examined changes in biomass C stock during the past 25 years.Our results showed that biomass C stock in northern China's grasslands was estimated at 557.5 Tg C(1 Tg=1012 g),with a mean density of 39.5 g C m-2 for above-ground biomass and 244.6 g C m-2 for below-ground biomass.An increasing rate of 0.2 Tg C yr-1 has been observed over the past 25 years,but grassland biomass has not experienced a significant change since the late 1980s.Seasonal rainfall(January-July) was the dominant factor driving temporal dynamics in biomass C stock;however,the responses of grassland biomass to climate variables differed among various grassland types.Biomass in arid grasslands(i.e.,desert steppe and typical steppe) was significantly associated with precipitation,while biomass in humid grasslands(i.e.,alpine meadow) was positively correlated with mean January-July temperatures.These results suggest that different grassland ecosystems in China may show diverse responses to future climate changes.

关键词： above-ground biomass alpine grasslands below-ground biomass carbon stock NDVI temperate grasslands

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Contrasting effects of nitrogen addition on litter decomposition in forests and grasslands in China

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Journal of Arid Land 2021年第7期13卷 717-729页

作者： SU Yuan MA Xiaofei GONG Yanming LI Kaihui HAN Wenxuan LIU Xuejun State Key Laboratory of Desert and Oasis Ecology Xinjiang Institute of Ecology and GeographyChinese Academy of SciencesUrumqi 830011China Bayanbulak Grassland Ecosystem Research Station Xinjiang Institute of Ecology and GeographyChinese Academy of SciencesBayanbulak 841314China University of Chinese Academy of Sciences Beijing 100049China Chinese Academy of Sciences Research Center for Ecology and Environment of Central Asia Urumqi 830011China Beijing Key Laboratory of Farmland Soil Pollution Prevention and Remediation College of Resources and Environmental SciencesChina Agricultural UniversityBeijing 100193China

Nitrogen(N)addition has profound impacts on litter-mediated nutrient cycling.Numerous studies have reported different effects of N addition on litter decomposition,exhibiting positive,negative,or neutral effects.Previous meta-analysis of litter decomposition under N addition was mainly based on a small number of samples to allow comparisons among ecosystem types.This study presents the results of a meta-analysis incorporating data from 53 published studies(including 617 observations)across forests,grasslands,wetlands,and croplands in China,to investigate how environmental and experimental factors impact the effects of N addition on litter decomposition.Averaged across all of the studies,N addition significantly slows litter decomposition by 7.02%.Considering ecosystem types,N addition significantly accelerates litter decomposition by 3.70%and 11.22%in grasslands and wetlands,respectively,clearly inhibits litter decomposition by 14.53%in forests,and has no significant effects on litter decomposition in croplands.Regarding the accelerated litter decomposition rate in grasslands due to N addition,litter decomposition rate increases slightly with increasing rates of N addition.However,N addition slows litter decomposition in forests,but litter decomposition is at a significantly increasing rate with increasing amounts of N addition.The responses of litter decomposition to N addition are also influenced by the forms of N addition,experiential duration of N addition,humidity index,litter quality,and soil pH.In summary,N addition alters litter decomposition rate,but the direction and magnitude of the response are affected by the forms of N addition,the rate of N addition,ambient N deposition,experimental duration,and climate factors.Our study highlights the contrasting effects of N addition on litter decomposition in forests and grasslands.This finding could be used in biogeochemical models to better evaluate ecosystem carbon cycling under increasing N deposition due to the differential responses of litter decomposition

关键词： litter decomposition rate N addition ambient N deposition litter quality meta-analysis forests grasslands

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Biomass Components and Environmental Controls in Ningxia grasslands

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Journal of Integrative Agriculture 2012年第12期11卷 2079-2087页

作者： WANG Kai-bo LI Jian-ping SHANGGUAN Zhou-ping State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences School of Agriculture Ningxia University State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water Conservation Chinese Academy of Sciences

Grassland plays an important role in the global carbon cycle and climate regulation. However, there are still large uncertainties in grassland carbon pool and also its role in global carbon cycle due to the lack of measured grassland biomass at regional scale or global scale with a unified survey method, particular for below-ground biomass. The present study, based on a total of 44 grassland sampling plots with 220 quadrats across Ningxia, investigated the characteristics of above-ground biomass （AGB）, below-ground biomass （BGB）, litter biomass （LB）, total biomass （TB） and root：shoot ratios （R：S） for six predominantly grassland types, and their relationships with climatic factors. AGB, BGB, LB and TB varied markedly across different grassland types, the median value ranging from 28.2-692.6 g m-2 for AGB, 130.4-2 036.6 g m-： for BGB, 9.2-82.3 g m2 for LB, and 168.0-2 681.3 g m-： for TB. R：S showed less variation with median values from 3.2 to 5.3 （excluding marshy meadow）. The different grassland types showed similar patterns of biomass allocation, with more than 70% BGB for all types. There is evidence of strong positive effects associated with mean annual precipitation （MAP） and negative effects associated with mean annual temperature （MAT） on AGB, BGB, and LB, although both factors have the opposite effect on R：S.

关键词： grasslands above-ground biomass （AGB） below-ground biomass （BGB） root：shoot ratios （R：S） mean annual precipitation （MAP） mean annual temperature （MAT）

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