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发布时间:2016-07-19  来源:土壤与农业可持续发展国家重点实验室  浏览:884

【青藏高原高寒草地土壤中脂肪酸的分布特征】Dai G H, Zhu S S, Liu Z G, Chen L T, He J S, Feng X J. 2016. Distribution of fatty acids in the alpine grassland soils of the Qinghai-Tibetan Plateau.Science China Earth Science, 59: 1329–1338, doi: 10.1007/s11430-016-5271-2


As an important biomarker, fatty acids (FAs) have been extensively used to trace the origin of organic matter in sediments and soils. However, studies of the distribution and abundance of FAs in alpine grassland soils are still rare, especially on the Qinghai-Tibetan Plateau (QTP), the highest plateau in the world, which contributes sediments to many large rivers in Asia. This study investigates the composition, distribution and source of FAs with increasing soil depths from 17 typical alpine grassland sites in the QTP. The most abundant FAs included the ubiquitous C16 FA and even-numbered long-chain FAs (C20–C30), indicating mixed inputs from microbial and higher plant sources. Source apportionment showed that higher plants were the dominant contributor of FAs (approximately 40%) in QTP soils. The abundance of FAs decreased with soil depth, with the highest value (1.08±0.09 mg/g OC) at a 0–10 cm depth and the lowest value (0.46±0.12 mg/g OC) at a 50–70 cm depth, due to much lower plant inputs into the deeper horizons. The total concentration of FAs was negatively correlated to the mean annual temperature (MAT; P<0.05) and soil pH (P<0.01), suggesting that the preservation of FAs was favored in low-MAT and low-pH soils on the QTP. The abundance of fresh OC source FAs increased significantly with the mean annual precipitation (MAP; P<0.05), indicating that high MAP facilitates the accumulation of fresh FAs in QTP soils. Other environmental parameters, such as the soil mineral content (aluminum and iron oxide), microbial community composition as well as litter quality and quantity, may also exert a strong control on the preservation of FAs in QTP soils and warrant further research to better understand the mechanisms responsible for the preservation of FAs in QTP soils.

  脂肪酸,作为一种重要的生物标志物,已被广泛用于土壤和沉积物中有机质来源的示踪。最近一项关于青藏高原高寒草地土壤中脂肪酸分布特征的研究,表明青藏高 原高寒草地土壤中的脂肪酸主要源于植物组织,低温和低的土壤pH条件有利于土壤中脂肪酸的保存,该项研究为进一步揭示全球气候变化背景下青藏高原土壤碳动 态提供了重要的理论依据。

  相关论文题目为:“Distribution of fatty acids in the alpine grassland soils of the Qinghai-Tibetan Plateau”,出版于2016年第7期SCIENCE CHINA earth sciences(《中国科学:地球科学》英文版),由中国科学院植物研究所戴国华博士担任第一作者,冯晓娟研究员担任通讯作者共同撰写。研究者以分子水平的生物标志物为主要技术手段,揭示了青藏高原高寒草地土壤中脂肪酸分布特征研究。

  青藏高原是世界上海拔最高的高原,也是亚洲许多大河沉积物的主要源。近年来,一些研究者指出青藏高原是全球气候变化的高度敏感区,全球气候变化会导致青藏 高原高寒草地退化和土壤有机质在微生物降解和河流迁移作用下的大量流失。然而目前对青藏高原土壤有机质的研究仍局限于碳、氮等整体参数的测定,而对青藏高 原高寒草地土壤中生物标志物的分析能更清晰的阐明全球气候变化背景下土壤的碳动态,并为示踪发源于青藏高原的河流沉积物的源提供重要信息。

  该研究利用分子水平的生物标志物技术,首次进行了青藏高原高寒草地土壤中脂肪酸分布特征研究。通过对对青藏高原高寒草地17个采样点不同深度的土壤样品中 生物标志物脂肪酸的检测分析,并结合环境要素(气温、降水、土壤理化性质)数据,揭示了青藏高原高寒草地不同土层深 度脂肪酸的组成、来源和分布特征。该研究发现:高等植物对青藏高原土壤中脂肪酸含量的贡献达40%以上。脂肪酸总含量与年均温和土壤pH值呈显著负相关关 系,因此低温和低土壤pH更有易于青藏高原土壤中脂肪酸的保存。研究者指出,未来还应加强关于其它环境因素,如土壤矿物含量(铁、铝氧化物)、微生物群落 组成、枯落物的质量和数量等对青藏高原土壤中脂肪酸保留所起作用的进一步研究,以便更好地理解青藏高原高寒草地土壤中脂肪酸的保留机理。该研究为进一步探 讨青藏高原土壤有机碳来源、周转时间及对气候敏感性方面奠定了理论基础。(来源:EurekAlert!)

【根际微生物的相互作用】Shi SJ, Erin E. Nuccio, Zhou J. Shi, Zhou JZ, Mary K. Firestone. The interconnected rhizosphere: High network complexity dominates rhizosphere assemblages. Ecology Letters, 2016, 19(8): 926-936


While interactions between roots and microorganisms have been intensively studied, we know little about interactions among root-associated microbes. We used random matrix theory-based network analysis of 16S rRNA genes to identify bacterial networks associated with wild oat (Avena fatua) over two seasons in greenhouse microcosms. Rhizosphere networks were substantially more complex than those in surrounding soils, indicating the rhizosphere has a greater potential for interactions and niche-sharing. Network complexity increased as plants grew, even as diversity decreased, highlighting that community organisation is not captured by univariate diversity. Covariations were predominantly positive (> 80%), suggesting that extensive mutualistic interactions may occur among rhizosphere bacteria; we identified quorum-based signalling as one potential strategy. Putative keystone taxa often had low relative abundances, suggesting low-abundance taxa may significantly contribute to rhizosphere function. Network complexity, a previously undescribed property of the rhizosphere microbiome, appears to be a defining characteristic of this habitat.

【CO2升高对生态系统的影响】K.E. Mueller, D.M. Blumenthal, E. Pendall, Y. Carrillo, F.A. Dijkstra, D.G. Williams, R.F. Follett, J.A. Morgan. Impacts of warming and elevated CO2 on a semi-arid grassland are non-additive, shift with precipitation, and reverse over time. Ecology, Letters, 2016, 19(8): 956-966


It is unclear how elevated CO2 (eCO2) and the corresponding shifts in temperature and precipitation will interact to impact ecosystems over time. During a 7-year experiment in a semi-arid grassland, the response of plant biomass to eCO2 and warming was largely regulated by interannual precipitation, while the response of plant community composition was more sensitive to experiment duration. The combined effects of eCO2 and warming on aboveground plant biomass were less positive in ‘wet’ growing seasons, but total plant biomass was consistently stimulated by ~ 25% due to unique, supra-additive responses of roots. Independent of precipitation, the combined effects of eCO2 and warming on C3 graminoids became increasingly positive and supra-additive over time, reversing an initial shift toward C4 grasses. Soil resources also responded dynamically and non-additively to eCO2 and warming, shaping the plant responses. Our results suggest grasslands are poised for drastic changes in function and highlight the need for long-term, factorial experiments.

【全球变化与固氮蓝藻】Paul Kardol, Clydecia M. Spitzer, Michael J. Gundale, Marie-Charlotte Nilsson, David A. Wardle. Trophic cascades in the bryosphere: the impact of global change factors on top-down control of cyanobacterial N2-fixation. Ecology, Letters, 2016, 19(8): 967-976


Trophic cascades in which predators regulate densities of organisms at lower trophic levels are important drivers of population dynamics, but effects of trophic cascades on ecosystem-level fluxes and processes, and the conditions under which top-down control is important, remain unresolved. We manipulated the structure of a food web in boreal feather mosses and found that moss-inhabiting microfauna exerted top-down control of N2-fixation by moss-associated cyanobacteria. However, the presence of higher trophic levels alleviated this top-down control, likely through feeding on bacterivorous microfauna. These effects of food-web structure on cyanobacterial N2-fixation were dependent on global change factors and strongly suppressed under N fertilisation. Our findings illustrate how food web interactions and trophic cascades can regulate N cycling in boreal ecosystems, where carbon uptake is generally strongly N-limited, and shifting trophic control of N cycling under global change is therefore likely to impact ecosystem functioning.

【土地利用与陆地生物多样性】Tim Newbold1,2,*, Lawrence N. Hudson3, Andrew P. Arnell1, Sara Contu3, Adriana De Palma3,4, Simon Ferrier5, Samantha L. L. Hill1,3, Andrew J. Hoskins5, Igor Lysenko4, Helen R. P. Phillips3,4, Victoria J. Burton3, Charlotte W. T. Chng3, Susan Emerson3, Di Gao3, Gwilym Pask-Hale3, Jon Hutton1,6, Martin Jung7,8, Katia Sanchez-Ortiz3, Benno I. Simmons3,4, Sarah Whitmee2, Hanbin Zhang3, Jörn P. W. Scharlemann1,8, Andy Purvis3,4. Has land use pushed terrestrial biodiversity beyond the planetary boundary? A global assessment. Science, 2016, Vol. 353, Issue 6296, pp. 288-291


Land use and related pressures have reduced local terrestrial biodiversity, but it is unclear how the magnitude of change relates to the recently proposed planetary boundary (“safe limit”). We estimate that land use and related pressures have already reduced local biodiversity intactness—the average proportion of natural biodiversity remaining in local ecosystems—beyond its recently proposed planetary boundary across 58.1% of the world’s land surface, where 71.4% of the human population live. Biodiversity intactness within most biomes (especially grassland biomes), most biodiversity hotspots, and even some wilderness areas is inferred to be beyond the boundary. Such widespread transgression of safe limits suggests that biodiversity loss, if unchecked, will undermine efforts toward long-term sustainable development.



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