Base cation concentrations in forest litter and topsoil have different responses to climate and tree species along elevational gradients   总被引：1，自引：0，他引：1  

XUE Feng  ZHAO Ming-fei  WANG Yu-hang  KANG Mu-yi  XING Kai-xiong  WANG Guo-yi  SHI Jing-jing  CHEN Chen  JIANG Yuan 《山地科学学报》2019,(1)

The forest litter is an essential reservoir of nutrients in forests, supplying a large part of absorbable base cations(BC) to topsoil, and facilitating plant growth within litter-soil system. To characterize elevational patterns of base cation concentrations in the forest litter and topsoil, and explore the effects of climate and tree species, we measured microclimate and collected the forest litter and topsoil(0-10 cm) samples across an elevational range of more than 2000 m(1243 ～ 3316 m a.s.l.),and analyzed the concentrations of BC in laboratory. Results showed that: 1) litter Ca concentration displayed a hump-shaped pattern along the elevational gradients, but litter K and Mg showed saddle-shaped patterns. Soil Ca concentration increased with elevation, while soil K and Mg had no significant changes. 2) Ca concentration in the forest litter under aspen(Populus davidiana) was significantly higher than that in all other species, but in topsoil, Ca concentration was higher under coniferous larch and fir(Larix chinensis and Abies fargesii). Litter K and Mg concentrations was higher under coniferous larch and fir, whereas there were nosignificant differences among tree species in the concentrations of K and Mg in topsoil. 3) Climatic factors including mean annual temperature(MAT), growing season precipitation(GSP) and non-growing season precipitation(NGSP) determined BC concentrations in the forest litter and topsoil. Soil C/N and C/P also influenced BC cycling between litter and soil. Observation along elevations within different tree species implies that above-ground tree species can redistribute below-ground cations, and this process is profoundly impacted by climate. Litter and soil Ca, K and Mg with different responses to environmental variables depend on their soluble capacity and mobile ability.  相似文献   

路基煤矸石填料土-水特征曲线试验研究     

陈仁朋  王朋飞  刘鹏  程威  康馨  杨微 《岩土力学》2020,41(2):372-378

煤矸石作为煤层开采和洗选过程中产生的废弃料，常用于路基填筑。压实的路基煤矸石填料存在双孔隙群结构，其土-水特征曲线（SWCC）具有双台阶现象。而SWCC与土体非饱和渗透系数密切相关，对路基内部水分运移以及路基长期累积变形有重要影响。为了探究压实度、粉粒含量、最大颗粒粒径对双台阶SWCC的影响，对路基煤矸石填料进行了一系列压力板试验，并采用描述双台阶SWCC的Bi-V-G公式拟合实测SWCC，分析了模型参数变化规律。试验结果表明，粉粒含量为5%时，不同压实度试样SWCC均存在双台阶现象；粉粒含量为50%时，随着压实度增大，试样SWCC由双台阶形过渡为单台阶形，在0.90和0.95压实度之间存在一个界限值，双台阶现象消失；增大压实度、提高粉粒含量或减小最大颗粒粒径，均会使SWCC台阶高差减小。随着压实度增大或粉粒含量提高，模型参数 、 （与进气值有关的参数）和 、 （与排水程度有关的参数）值均逐渐减小，试样大、小孔隙部分均进气值增大，持水能力提高。  相似文献   

Maximum Entropy and Random Forest Modeling of Mineral Potential: Analysis of Gold Prospectivity in the Hezuo–Meiwu District,West Qinling Orogen,China     

Zhang  Shuai  Xiao  Keyan  Carranza  Emmanuel John M.  Yang  Fan 《Natural Resources Research》2019,28(3):645-664

Natural Resources Research - This study tested and compared the mineral potential mapping capabilities of the random forest (RF) and maximum entropy (MaxEnt) algorithms using gold deposit...  相似文献   

Changes of Biogenic Elements in Phragmites australis and Suaeda salsa from Salt Marshes in Yellow River Delta,China     

JIA Jia  BAI Junhong  WANG Wei  ZHANG Guangliang  WANG Xin  ZHAO Qingqing  ZHANG Shuai 《中国地理科学(英文版)》2018,(3)

Little information is available on biogenic elements(carbon, nitrogen, phosphorus and sulfur) and the ecological stoichiometric characteristics of plants in coastal wetlands. To investigate the contents of carbon, nitrogen, phosphorus and sulfur of plants, and their ecological stoichiometric characteristics in the Yellow(Huanghe) River Delta, plant samples were collected from two typical salt marshes(Suaeda salsa and Phragmites australis wetlands) during the period of from August to October in 2007, and the ratios of C/N, C/P, N/P, C/N/P and C/N/P/S were calculated. Results showed that during the studying period, plant C, N and P were lower than the global average values, and plant N and P were lower than the China's average values. Leaf C and S in Suaeda salsa were significantly lower than those in Phragmites australis(P 0.05), and leaf N and P in Suaeda salsa and Phragmites australis showed no significant differences(P 0.05). Average C/N ratios were 23.75 in leaf, 73.36 in stem, 65.67 in root of Suaeda salsa, and 33.77 in leaf, 121.68 in stem, 97.13 in root of Phragmites australis. Average C/N ratios of Suaeda salsa and Phragmites australis were all great than 25, indicating the salt marsh in the Yellow River Delta is an N limitation system. Average C/P ratios were 276.78 in leaf, 709.28 in stem and 1031.32 in root of Suaeda salsa, and 536.94 in leaf, 768.13 in stem and 875.22 in root of Phragmites australis. The average N/P ratios of Suaeda salsa were 12.92 in leaf, 10.77 in stem and 10.91 in root, and the average N/P ratios of Phragmites australis were 16.40 in leaf, 7.40 in stem and 6.92 in root, indicating the Suaeda salsa wetlands were N limited and Phragmites australis wetlands were N limited in August and P limited in October in 2007. The average C/N, C/P and C/N/P ratios in Suaeda salsa and Pragmites australis were higher than the global average values, indicating the lower quality of organic matter provided by wetland plants in the Yellow River delta.  相似文献   

Soil Organic Carbon Contents and Stocks in Coastal Salt Marshes with Spartina alterniflora Following an Invasion Chronosequence in the Yellow River Delta,China     

ZHANG Guangliang  BAI Junhong  JIA Jia  WANG Xin  WANG Wei  ZHAO Qingqing  ZHANG Shuai 《中国地理科学(英文版)》2018,(3)

Plant invasion alters the fundamental structure and function of native ecosystems by affecting the biogeochemical pools and fluxes of materials and energy. Native(Suaeda salsa) and invasive(Spartina alterniflora) salt marshes were selected to study the effects of Spartina alterniflora invasion on soil organic carbon(SOC) contents and stocks in the Yellow River Delta. Results showed that the SOC contents(g/kg) and stocks(kg/m~2) were significantly increased(P 0.05) after Spartina alterniflora invasion of seven years, especially for the surface soil layer(0–20 cm). The SOC contents exhibited an even distribution along the soil profiles in native salt marshes, while the SOC contents were gradually decreased with depth after Spartina alterniflora invasion of seven years. The natural ln response ratios(Ln RR) were applied to identify the effects of short-term Spartina alterniflora invasion on the SOC stocks. We also found that Spartina alterniflora invasion might cause soil organic carbon losses in a short-term phase(2–4 years in this study) due to the negative Ln RR values, especially for 20–60 cm depth. And the SOCD in surface layer(0–20 cm) do not increase linearly with the invasive age. Spearman correlation analysis revealed that silt + clay content was exponentially related with SOC in surface layer(Adjusted R~2 = 0.43, P 0.001), suggesting that soil texture could play a key role in SOC sequestration of coastal salt marshes.  相似文献   

景电灌区移民对祁连山植被恢复的相对生态价值          下载免费PDF全文

赵建林  康德奎  彭维恩  王建礼  史中兴  陈天顺  董志洋  汪杰  常兆丰 《干旱区地理》2020,43(1):182-189

近些年来，生态系统的服务价值研究已成为生态学以及生态经济学领域中的一个热点问题。祁连山被称为伸进西北干旱区的一座湿岛，在我国“一带一路”建设中占有重要地位。景电灌区兴建以来从祁连山移出了大量农牧民。那么，景电灌区移民对祁连山植被恢复的生态价值如何呢？以景电灌区移民涉及到的祁连山东端景泰、古浪、天祝3县山区为研究区，用价值工程方法对从祁连山区向景电灌区移民退耕退牧还林还草的生态价值做了分析，并与模型因子当量法的计算结果进行了比较。结果表明：祁连山向景电灌区移民退耕退牧还林还草总的生态价值为37.458 1×10⁸元。其中，退耕还林还草的生态价值为37.438 6×0⁸元，退牧后草场植被盖度增加的生态价值为194.79×104元。计算结果为用COSTANZA和谢高地模型因子当量法计算得的祁连山向景电灌区移民退耕退牧还林还草总的生态服务价值40.054 0×0⁸元的93.52%。两种方法计算结果祁连山向景电灌区移民退耕退牧还林还草总的生态价值为景电工程年总成本1.45×0⁸元的25.8~27.6倍。两种计算结果一致表明，景电灌区生态移民对祁连山植被恢复的生态价值十分突出。由此也可以看出，COSTANZA和谢高地模型因子当量法适用于祁连山的生态服务价值分析。  相似文献   

陇中黄土高原丘陵沟壑区不同植被恢复模式下次降雨产流产沙特征   总被引：1，自引：0，他引：1       下载免费PDF全文

朱燕琴  赵志斌  齐广平  康燕霞  赵霞 《干旱区地理》2020,43(4):920-927

基于甘肃省清水县汤峪河径流小区2015—2017年的观测数据,研究不同植被恢复模式条件下坡面次降雨入渗、产流产沙特征。结果表明：不同植被恢复模式条件下的土壤入渗量与降雨强度呈二次函数关系,存在入渗量达到最大值的临界降雨强度。入渗速率与降雨历时可以用幂函数关系表达,符合考斯恰可夫入渗模型。不同植被恢复模式条件下的产流率在0.003 3~0.003 6 mm·min^-1之间,相对裸地的减流率为54%~58%。产流率与降雨强度之间呈二次函数关系（R²>0.88）,产流率的主要影响因素是降雨强度。径流含沙量平均值乔灌混合区（3.13 g·L^-1）>灌木林（2.95 g·L^-1）>乔木林（2.79 g·L^-1）>草地（2.58 g·L^-1）,径流含沙量与降雨强度呈线性递增函数关系。裸地的产沙量显著高于各植被小区（P<0.05）,是各植被小区的43~57倍,各植被小区的减沙率在93%~94%之间,减沙效益高于其减流效益。各植被坡面土壤流失量与降雨侵蚀力呈线性递增函数关系;产流率与侵蚀产沙率之间呈极显著正相关关系（P<0.01）,二者间可采用二次函数关系表达。本研究成果可为黄土高原丘陵沟壑区水土保持优化配置提供理论依据。  相似文献   

Characteristics of Permeability Changes in Bituminous Coal Under Conditions of Stress Variation Due to Repeated Mining Activities     

Huang  Mengqian  Zhang  Lei  Zhang  Cun  Chen  Shuai 《Natural Resources Research》2020,29(3):1687-1704

The factors affecting permeability change under repeated mining of coal seams are important study aspects that need to be explored. This study combined various stress variation characteristics of protective seam mining and simplified the stress path of repeated mining in protective seam mines. Based on the results from the bespoke gas flow and displacement testing apparatus, seepage tests for simulated repetitive mining were carried out. The results simulated the actual behavior very well. With any drastic increase in the mining influence, the axial deviation stress in the stress path increased, and the greater the difference in coal permeability during the unloading and stress recovery stage, the more substantial the increase in permeability. The change in coal permeability was significantly influenced by the severity of simulated repeated mining cycles. When the mining stress exceeded a critical value, the permeability of the coal sample increased with the increase in the number of loading and unloading cycles, but the reverse was true when the mining stress was lower than the critical value. The effective sensitivity of seepage to the applied stress decreased with an increase in the number of stress cycles. With a decrease in the deviation stress, that is, with lower severity of mining influence, the effective sensitivity of coal seepage to stress gradually decreased.

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虚拟地理环境中基于多模式的多人动作捕捉方法     

易超  陈斌  袁帅  徐丙立 《地球信息科学学报》2019,21(3):305-314

虚拟地理环境对人类理解、探索地理现象以及发现地理现象之间的联系起到很重要的作用。在基于VR技术的虚拟地理环境中更高效,更自然的交互对虚拟地理环境系统的可用性以及理解、探索地理现象的效率至关重要。当前,人机交互中更自然便捷的交互依赖于动作捕捉技术,而现有的基于单种捕捉模式的动作捕捉方式,易受到遮挡、定位漂移等的影响,捕捉精度受到限制,并只能捕捉单个人的动作,不能满足虚拟地理环境对动作捕捉技术提出的特殊需求。针对单种模式的动作捕捉设备应用于虚拟地理环境受到的限制,本文分析了虚拟地理环境系统中的交互需求以及其对动作捕捉技术提出的特殊需求,创新性的提出了一种基于多种动作捕捉模式以捕捉多人动作的方法。本文方法集中于如何融合基于多种模式的多台设备的动作数据,描述了多人动作捕捉框架及其涉及到的技术,在动作捕捉效果上具有明显提升,能够捕捉多人动作,并开发了原型系统对此方法进行了验证。  相似文献   

“地理素养与测绘技能”双驱动的GIS专业大学生创新能力培养模式的探索     

蔡忠亮  翁敏  苏世亮  亢孟军  费腾  田晶  任福 《测绘通报》2020,(8):148-152

在信息技术快速发展和万众创新、大众创业的时代背景下，创新与创新人才已成为国家发展的重要推动力，创新教育和创新人才培养成为高校的重要任务。本文以武汉大学地理信息科学（GIS）专业为例，结合专业特点和优势，探索了"地理素养、测绘技能"驱动下的GIS专业大学生创新能力的培养模式和"厚基础、重知识、强技能"的贯通式培养途径。围绕创新人才培养和成长的内在因素和外部条件，从人才培养方案与课程体系、创新型教师团队与新型教学方法、教学科研创新平台与创新条件、创新人才发展评价与激励机制等4个方面开展了创新型发展探索。结合实践表明，本模式取得了显著的创新成果，产生了良好的示范辐射作用。  相似文献