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Seasonal patterns of root and shoot interactions in an alpine meadow on the Tibetan Plateau

Journal of Plant Ecology 2012年第2期5卷 182-190页

作者： Minghua Song Qiwu Hu yuqiang tian Hua Ouyang Key Laboratory of Ecosystem Network Observation and Modelling Institute of Geographical Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101People’s Republic of China

Aims Numerous studies have showed that the balance between negative and positive plant–plant interactions shifted along environmental *** little is known how the positive or negative plant–plant interactions varied with temporal fluctuating habitat conditions and plant ontogenetic *** In a 2-year experiment,the four perennial grasses(Kobresia humilis,Stipa aliena,Elymus nutans and Saussurea superba)were grown under four interaction treatments(no root or shoot interaction,only shoot interaction,only root interaction,root and shoot interaction).Intensity of above-and belowground interactions is proposed to vary with the fluctuation of seasonal climatic conditions and soil available *** we report measurements of above-and belowground interactions during entire growing *** between plant interaction intensity and seasonal soil available N as well as habitat climate conditions was also *** findings Our experiment found that root interactions had negative effect on plant growth for the four species during growing ***,both negative and positive shoot interactions occurred among the four *** there being shoot facilitative effect for *** and ***,the full interaction was negative,suggested that root interaction take more important role on plant growth than that of shoot *** interaction between root and shoot effect varied as a function of species identity and growth *** weak correlation of plant interaction intensity to habitat environmental factors suggested that plant ontogenetic characteristics may be primary factors causing temporal variation in plant interaction.

关键词： competition facilitation growing season ontogenetic phase habitat environmental conditions

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Interactive effects of soil temperature and moisture on soil N mineralization in a Stipa krylovii grassland in Inner Mongolia, China

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Journal of Arid Land 2014年第5期6卷 571-580页

作者： Yue LI YingHui LIU YaLin WANG Lei NIU Xia XU yuqiang tian State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal University Academy of Disaster Reduction and Emergency Management Beijing Normal University College of Resources Science and Technology Beijing Normal University

Determining soil N mineralization response to soil temperature and moisture changes is challenging in the field due to complicated effects from other factors. In the laboratory, N mineralization is highly dependent on temperature, moisture and sample size. In this study, a laboratory incubation experiment was carefully designed and conducted under controlled conditions to examine the effects of soil temperature and moisture on soil N mineralization using soil samples obtained from the Stipa krylovii grassland in Inner Mongolia, China. Five temperature（i.e. 9℃, 14℃, 22℃, 30℃ and 40℃） and five moisture levels（i.e. 20%, 40%, 60%, 80% and 100% WHC, where WHC is the soil water holding capacity） were included in a full-factorial design. During the 71-day incubation period, microbial biomass carbon（MBC）, ammonium nitrogen（NH4 ^＋-N） and nitrate nitrogen（NO3^--N） were measured approximately every 18 days; soil basal respiration for qCO2 index was measured once every 2 days（once a week near the end of the incubation period）. The results showed that the mineral N production and net N mineralization rates were positively correlated with temperature; the strongest correlation was observed for temperatures between 30℃ and 40℃. The relationships between moisture levels and both the mineral N production and net N mineralization rates were quadratic. The interaction between soil temperature and moisture was significant on N mineralization, i.e. increasing temperatures（moisture） enhanced the sensitivity of N mineralization to moisture（temperature）. Our results also showed a positive correlation between the net nitrification rate and temperature, while the correlation between the NH4 ^＋-N content and temperature was insignificant. The net nitrification rate was negatively correlated with high NH4 ^＋-N contents at 80%–100% WHC, suggesting an active denitrification in moist conditions. Moreover, qCO2 index was positively correlated with temperature, especially at 80% WHC. With a low net

关键词： soil N mineralization soil temperature soil moisture Stipa krylovii grassland

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Plant community dynamics during the growing season of typical ecosystems on the Tibetan Plateau

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Geography and Sustainability 2020年第4期1卷 266-274页

作者： Xiaoxia Chen yuqiang tian Yong Zhang Yu Cui Yan Zhao Weijian Sun Center for Human-Environment System Sustainability(CHESS) State Key Laboratory of Earth Surface Processes and Resource EcologyBeijing Normal UniversityBeijing 100875China School of Natural Resources Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China Institute of Grassland Research Chinese Academy of Agricultural SciencesHohhot 010010China

The relationships between vegetation and environmental factors have always been a core concern of *** dynamic characteristics of plant communities during the growing season can directly reflect these relation-ships,so we examined this issue for three typical ecosystems on the Tibetan *** the growing season,the dominant species remained stable while non-dominant species changed significantly in the alpine meadow and alpine steppe and a mono-dominant community was found in the temperate desert *** to the seasonal variations of temperature and soil water content,plant species diversity varied significantly during the growing *** richness,Pielou evenness and Simpson diversity indices differed significantly in the alpine meadow and alpine *** total biomass of these three ecosystems was the largest during the middle growing *** was greater in the alpine meadow than the alpine steeps or temperature *** root-to-shoot ratio was the lowest during the middle growing season for the alpine meadow and alpine steppe and largest during the early growing season for temperate desert *** showed the belowground and total biomass were greatly affected by soil physicochemical *** linear stepwise regression showed the above ground biomass was greatly affected by relative atmospheric humidity and belowground and total biomass were greatly affected by soil organic carbon,total nitrogen at 0-20 cm soil depth and pH at 10-20 cm soil *** findings pro-vide insights into understanding the relationships between vegetation and environmental factors and promote the sustainable utilization of local grasslands on the Tibetan Plateau.

关键词： Community dynamics Species diversity Root-to-shoot ratio Growing season Tibetan Plateau Grasslands

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Shrubs proliferated within a six-year exclosure in a temperate grassland—Spatiotemporal relationships between vegetation and soil variables

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Research in Cold and Arid Regions 2014年第2期6卷 139-149页

作者： Yong Zhang Qiong Gao Li Xu Mei Yu yuqiang tian State Key Laboratory of Earth Surface Processes and Resources Ecology College of Natural Resources and TechnologyBeijing Normal University Department of Environmental Science University of Puerto Rico-Rio Piedras

Overgrazing has been considered one of the maj or causes that trigger shrub encroachment of grassland. Proliferation of shrubs in grassland is recognized as an important indicator of grassland degradation and desertification. In China, various conservation measures, including enclosures to reduce livestock grazing, have been taken to reverse the trend of grassland desertification, yet shrubs have been reported to increase in the grasslands over the past decades. In late 2007, we set up a 400-m-by-50-m exclosure in a long-term overgrazed temperate grassland in Inner Mongolia, with the ob- jective to quantify the spatiotemporal relationship between vegetation dynamics, soil variables, and grazing exclusion. Soil moisture was continuously monitored within the exclosure, and cover and aboveground biomass of the shrubs were measured inside the exclosure in 2007, 2009, 2010, 2012, and 2013, and outside the exclosure in 2012 and 2013. We found the average shrub cover and biomass significantly increased in the six years by 103 % and 120%, respectively. The result supported the hypothesis that releasing grazing pressure following long-term overgrazing tends to trigger shrub invasion into grassland. Our results, limited to a single gradient, suggest that any conservation measures with quick release of overgrazing pressure by enclosure or other similar means might do just the opposite to accelerate shrub en- croachment in grassland. The changes in vegetation cover and biomass were regressed on the temporal average of the soil moisture content by means of the generalized least square technique to quantify the effect of the spatial autocor- relation. The result indicates that the grass cover and biomass significantly increased with the top, but decreased with the bottom layer soil moisture. The shrub cover and biomass, on the other hand, decreased with the top, but increased with bottom soil moisture, although the regression coefficients for the shrubs were not statistically sig

关键词： shrubs encroachment in grassland two-layered soil model grassland conservation spatial autocorrelation northern China

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Effect of rainfall interannual variability on the biomass and soil water distribution in a semiarid shrub community

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Science China(Life Sciences) 2010年第6期53卷 729-737页

作者： LIU JunShanXU XiaZHANG Yong,tian yuqiang & GAO Qiong State Key Laboratory of Earth Surface Processes and Resource Ecology,College of Resources Science & Technology,Beijing Normal University,Beijing 100875,China State Key Laboratory of Earth Surface Processes and Resource Ecology College of Resources Science & Technology Beijing Normal University Beijing China

The dynamics of biomass and soil moisture in semiarid land is driven by both the current rainfall and the ecosystem *** on a meta-analysis of existing experiments,an ecosystem model was used to calculate the effect of the rainfall interannual variability on the pattern of biomass and soil moisture in a shrub *** was found that rainfall interannual variability enabled shrubs to be more competitive than grasses,and to maintain the dominant role over a longer *** rainfall interannual variability resulted in complex soil moisture *** soil water recharge in wet years alternated with discharge in drought years.

关键词： rainfall shrub community Artemisia ordosica ecosystem model ecohydrology

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Distribution characteristics of SOM and nitrogen on the eastern slope of Gongga Mountain

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Journal of Geographical Sciences 2004年第4期14卷 481-487页

作者：王琳欧阳华彭奎 tian yuqiang ZHANG Feng Institute of Geographic Sciences and Natural Resources Research CASBeijing 100101China Graduate School of Chinese Academy of SciencesBeijing 100039China Institute of Geographic Sciences and Natural Resources Research CASBeijing 100101China

The distribution of soil organic matter (SOM) and nitrogen on Gongga Mountain was studied in this paper. The results showed that the content of SOM and nitrogen (N) of A horizon had an ascending trend with the increase of the elevation. The vegetation types distributed higher than the mixed broad-leaved and coniferous forest have the irregular trends. In the transitional zone vegetation such as mixed trees and treeline, the content of SOM and N is higher than other vegetation types. The distribution of SOM and N of A horizon is dependent on the synthetic effect of climate and vegetation types. The vertical distribution of SOM and N in soil profiles has the similar trends for all kinds of vegetation types, i.e., the content of A horizon is higher than that of the B and C horizons, which is the same to the distribution of dead animal and plant in soil. The soil C:N is between 7 and 25, which is relatively low comparing to the appropriate C:N of 25-30. The ratio of soil carbon to nitrogen (C:N)increases with the increase of the elevation, but its vertical distribution in soil horizons varies with different vegetation types. The N exists in SOM mainly in the form of organic nitrogen, and the soil C:N correlates significantly with SOM.

关键词： gongga mountain vertical gradient soil organic matter nitrogen

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低地板轻轨车防折弯液压系统减振阻尼特性研究

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机床与液压 2019年第11期47卷 71-74页

作者：丁问司田宇强熊艳伦华南理工大学机械与汽车工程学院广东广州510641 广州市蕴泰精密机械有限公司广东广州510503

以低地板轻轨车防折弯液压系统为研究对象,针对系统的横向减振功能,在建立相应数学模型基础上分析了组合阻尼形成原理,并利用AMESim系统对阻尼特性进行了仿真计算。进一步分析了缓冲阀门组设计参数变化对系统阻尼特性的影响。研究表明:... 详细信息

以低地板轻轨车防折弯液压系统为研究对象,针对系统的横向减振功能,在建立相应数学模型基础上分析了组合阻尼形成原理,并利用AMESim系统对阻尼特性进行了仿真计算。进一步分析了缓冲阀门组设计参数变化对系统阻尼特性的影响。研究表明:缓冲阀门组中的节流阀与限压阀组合形成了具有多拐点特征的多段抛物线组合的防折弯液压系统阻尼特性。限压阀的开启压力决定着系统阻尼力峰值,节流阀孔径决定着与阻尼力峰值所对应的转向活塞最小临界速度。研究为防折弯系统的设计和优化提供了参考。

关键词：防折弯液压系统阻尼特性 AMESim仿真

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邢台矿洗煤厂串联浮选工业性试验研究分析

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煤炭与化工 2020年第3期43卷 104-107,111页

作者：田玉强冀中能源股份有限公司邢台矿河北邢台054000

邢台矿洗煤厂针对因浮选入料中高灰细泥导致的浮选效果一直不理想的情况,根据自身生产条件及设备布置特点,通过对管路改动,实现了单开B系统时浮选机与浮选柱的串联浮选,且进行了2次工业性试验,取得了较好的效果,为进一步实现串联浮选改... 详细信息

邢台矿洗煤厂针对因浮选入料中高灰细泥导致的浮选效果一直不理想的情况,根据自身生产条件及设备布置特点,通过对管路改动,实现了单开B系统时浮选机与浮选柱的串联浮选,且进行了2次工业性试验,取得了较好的效果,为进一步实现串联浮选改造奠定了基础。

关键词：高灰细泥粒级串联浮选

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倾转三旋翼垂直起降无人机悬停姿态控制

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农业机械学报 2018年第10期49卷 16-22页

作者：许景辉马贺周建峰田钰强韩文霆西北农林科技大学水利与建筑工程学院陕西杨凌712100 西北农林科技大学旱区农业水土工程教育部重点实验室陕西杨凌712100 密苏里大学食品与生物工程系哥伦比亚mo65211 西北农林科技大学中国旱区节水农业研究院陕西杨凌712100

针对一种倾转三旋翼垂直起降(VTOL)飞行器在悬停状态下的姿态控制问题,设计了一种基于STM32系列微控制器的飞行控制系统。采用十轴组合惯性导航模块实时采集载机平台姿态信息,并结合基于四元数的互补滤波算法进行姿态信息解算。针对无... 详细信息

针对一种倾转三旋翼垂直起降(VTOL)飞行器在悬停状态下的姿态控制问题,设计了一种基于STM32系列微控制器的飞行控制系统。采用十轴组合惯性导航模块实时采集载机平台姿态信息,并结合基于四元数的互补滤波算法进行姿态信息解算。针对无人机姿态控制实时性和精度要求高的特点,采用串级PID控制算法对载机进行悬停状态下的姿态控制。实验结果表明:串级PID控制算法在悬停状态下能够对倾转三旋翼垂直起降飞行器进行快速、稳定、准确的姿态控制,并具有一定的鲁棒性。在横滚角的内环采用PD控制(Kp为8.371,Kd为3.015),外环采用PD控制(Kp为5.1,Kd为1.15);俯仰角的内环采用PD控制(Kp为3.137,Kd为1.6),外环采用PID控制(Kp为3.43,Ki为0.003,Kd为3.97);偏航角采用PI控制(Kp为9.30,Ki为0.11)时,其悬停状态下具有最优姿态控制效果。研究结果对倾转三旋翼垂直起降飞行器飞行控制的后续研究具有指导作用。

关键词：倾转三旋翼无人机垂直起降串级PID 姿态控制

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青藏高原高寒草地植物光合与土壤呼吸研究进展

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生态环境学报 2009年第2期18卷 711-721页

作者：田玉强高琼张智才张勇朱锴北京师范大学资源学院地表过程与资源生态国家重点实验室北京100875

青藏高原是全球变化研究的热点地区之一,而高寒草地碳过程研究一直都是全球变化研究中的重要课题。简要综述了近年来青藏高原高寒草地的重要碳过程-植物光合与土壤呼吸的研究进展和不足,并展望未来的研究热点。主要包括高寒草地植物叶... 详细信息

青藏高原是全球变化研究的热点地区之一,而高寒草地碳过程研究一直都是全球变化研究中的重要课题。简要综述了近年来青藏高原高寒草地的重要碳过程-植物光合与土壤呼吸的研究进展和不足,并展望未来的研究热点。主要包括高寒草地植物叶片光合生理特征及其对强太阳辐射、低CO2分压、低温等高寒生境特征的适应,植物群落光合生理特征,植物生产力与植被碳库状况;高寒草地土壤呼吸日变化与季节变化特征及其影响因子分析,土壤有机碳(SOC)储量及其周转研究等。目前高寒草地的植物光合生理研究多基于叶片水平,群落和生态系统水平研究较少;已有的土壤呼吸研究多为对总土壤呼吸的研究,而将总呼吸区分为根呼吸、根际微生物呼吸、植物凋落物的微生物呼吸、有根区的土壤有机质分解以及无根区的土壤有机质分解等仍然是目前的研究难点。并且目前高寒草地植物光合与土壤呼吸研究缺乏学科交叉,多为相互独立、单一的植物生理学、生态学或土壤学研究,因此有关植物光合与土壤呼吸的整合性研究将是未来该区域碳循环研究的一个新方向。有关这一独特地域单元碳过程整合研究的大量开展,必将进一步提高人们对青藏高原区域碳循环机理的认知水平。

关键词：青藏高原高寒草地植物光合土壤呼吸

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