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1.
大兴安岭多年冻土区不同土地利用方式对土壤碳、氮组分的影响 总被引：1，自引：0，他引：1
《科技风》2020,(12)
为研究大兴安岭多年冻土区不同土地利用方式下不同深度土壤碳氮的特征,对大兴安岭漠河市沼泽、白桦林、落叶松、耕地4种土地利用方式下土壤碳氮储量进行了分析。结果表明4种土地利用方式总碳、有机碳、铵态氮、硝态氮存在显著差异,且均随土壤深度增加而降低。其中在0-10cm土层,沼泽总碳含量显著高于耕地、落叶松(P0.01);白桦林与耕地的土壤有机碳含量具有显著性差异(P0.05);沼泽铵态氮含量与白桦林具有极显著差异(P0.01),与落叶松具有显著性差异(P0.05);沼泽的硝态氮含量远远大于其他三种土地利用方式(P0.01)。10-30cm土层含量规律与土壤表层相似。通过相关性分析表明,土壤有机碳对铵态氮、硝态氮影响较大(P0.01)。大兴安岭多年冻土区,不同土地利用方式的碳、氮含量具有规律性、差异性。不同土地利用方式影响壤中碳、氮的含量。 相似文献
2.
中国东部地区典型森林类型土壤有机碳储量分析 总被引：28，自引：0，他引：28
森林土壤有机碳(SOC)是土壤有机碳库的重要组成部分，在土壤有机碳库研究中有着重要作用。本文对中国东部地区7个典型森林的土壤样区碳储量进行了野外调查与对比研究，分析了6种土壤类型和28种植被类型的SOC储量及其随深度的变化。结果表明，调查区域内SOC储量的分布范围在4.01kg～30.12kg/m3之间，在各土壤类型中，长白山棕黑毡土的有机碳储量最高，SOC储量为24.41kg/m3，千烟洲红壤的有机碳储量最低，SOC储量为6.47kg±1.01kg/m3；在各植被类型中，鸡公山的黄山松林SOC储量最高，SOC储量为30.12kg±22.76kg/m3。千烟洲常绿阔叶林土壤的有机碳储量最低，SOC储量为4.01kg±3.56kg/m3，部分地区SOC储量还有一定的增长潜力。年均温与SOC储量呈负相关，但7个典型森林类型土壤碳储量的分布，在由北向南的方向上没有明显的特征。初步分析认为，土地利用类型是影响本研究所调查地区SOC储量分布的主要因子。7个典型森林类型土壤碳储量随土层深度的下降而降低，其中自然林土壤碳储量降低幅度相对较大，人工林土壤碳储
量降低的幅度相对较小。人工林土壤剖面上层SOC储量相对较低，导致了人工林土壤整体有机碳储量比较低。 相似文献
3.
典型峰林平原土壤有机碳储量和分布特征研究 总被引：2，自引：0，他引：2
以桂林峰林平原岩溶区为例分析了土壤和土壤剖面的有机碳含量,计算了土壤有机碳密度以及9.27 km2研究区的土壤有机碳库储量。研究表明:土壤有机碳含量变化范围为2.46～17.89 g.kg-1,且随着土壤深度的增加而呈现递减的趋势。水田中土壤剖面的土壤有机碳含量变化幅度最大;表层0～20cm的土壤有机碳密度2.29～5.35 kg.m-2,平均值为3.65 kg.m-2;而0～100cm土壤有机碳密度值范围为5.88～13.54 kg.m-2,平均碳密度为9.83 kg.m-2。0～20cm土壤有机碳密度为水田>弃耕地>旱地>易涝地>园地>林地>草地,而0～100cm土壤有机碳密为弃耕地>园地>旱地>水田>林地>易涝地>草地。研究区表层0～20cm的土壤有机碳储量为2.785×104t,而0～100cm的土壤有机碳储量为8.514×104t。表层土壤0～20cm土壤有机碳储量占0～100cm的32.7%。与受人类活动干扰较少的重庆金佛山研究结果相比,本区的土壤有机碳密度明显偏低,这意味着岩溶区土壤有机碳容易受到人为干扰、易分解、易流失。而不同的土地利用、耕作方式及管理措施也影响着土壤碳库的大小,合理安排土地利用方式,将有助于土壤有机碳的累积和农业生产活动。 相似文献
4.
北京市耕地表层土壤有机碳分布及其影响因素 总被引：1，自引：0，他引：1
土壤有机碳既是影响全球气候变化的生态因子,也是影响耕地质量的肥力因子,研究耕地土壤有机碳分布特征及其影响因素对增加耕地碳储量和提升耕地生产能力具有重要指导意义。本文以北京市为研究区,以第二次土壤普查的土壤类型及质地数据、2010年测土配方施肥项目土壤养分调查成果、数字高程模型（DEM）及耕地种植类型分布图为基础数据,分析区域耕地土壤有机碳密度及储量空间分布特征。结果表明：①2010年北京市耕地表层土壤平均有机碳密度为22.51 t/hm 2,碳储量为990.34×10 4 t;②北京市西北部山区以及城市近郊区耕地碳密度较大,各区县中耕地表层土壤平均有机碳密度最大的是门头沟区,达39.93 t/hm 2;③地形、土壤类型、土壤质地及种植类型对耕地土壤有机碳密度均有影响,具随着海拔升高耕地土壤有机碳密度整体呈增加趋势;土壤类型为棕壤、褐土的耕地有机碳密度显著高于其他类型,整体表现出土壤质地越黏重土壤有机碳密度越大的趋势;利用方式为非粮作物的耕地土壤有机碳密度略高于粮食作物;④综合分析表明,在中山、低山区域春玉米土壤碳密度最高,而在丘陵、平原区则是露天菜、设施农业碳密度最高。当前北京市耕地利用调整应综合考虑当地地貌地形、土壤条件以及人为利用因素对耕地表层土壤有机碳的影响,因地制宜提高或保持耕地固碳能力。 相似文献
5.
江苏省土地利用变化对陆地生态系统碳储量的影响 总被引：10，自引：1，他引：9
土地利用变化是影响陆地生态系统碳储量变化的重要驱动因素,目前相关研究主要集中在土地利用变化对单一生态系统的影响,如土壤生态系统、森林生态系统、农地、草地生态系统等,本文以江苏省为研究区域,综合考虑了整个生态系统来探讨土地利用变化对碳储量的影响。文中涉及到的数据包括土地利用数据、土壤数据、植被数据。利用ArcGIS9.3分析1985到2005年江苏省土地利用变化,根据不同的方法,分别计算了江苏省不同土地利用类型的土壤碳储量和植被碳储量,并分析其对土地利用变化的影响,主要结论如下：①江苏省陆地生态系统总碳储量为975.72Tg,其中土壤碳储量为922.03Tg,占有机碳总储量的94.5%,土壤平均碳密度为9.41kg/m2,植被碳储量为53.69Tg,占有机碳总储量的5.5%,植被平均碳密度为1.791kg/m2;②1985-2005年江苏省陆地生态系统有机碳储量共减少9.73Tg,其中土壤有机碳储量减少7.54Tg,植被有机碳储量减少2.19Tg,土地利用变化造成了有机碳的释放,释放量占江苏省陆地生态系统有机碳储量的1%;③建设占用耕地是引起碳储量变化的主要原因,但总体而言,人类土地利用活动对江苏省陆地生态系统总碳储量平衡的扰动并不大;④应通过加强耕地保护、增加碳汇和土地利用结构优化等方式来降低人为活动对自然碳过程的影响。 相似文献
6.
新疆灰漠土耕地面积176万hm2,为新疆农业的发展起关键支撑作用。本研究基于新疆灰漠土农田肥力长期监测试验,选择其中不施肥、施化肥和化肥配施有机肥、秸秆的六个处理,对不同施肥处理下土壤表层（0~20cm）和亚表层（20~40cm）土壤碳储量变化特征进行了研究。结果表明：长期不施肥或施用化肥、有机肥均能提高灰漠土表层和亚表层土壤有机碳储量,其中表层土壤有机碳储量提高（4.0~43.7）tC/hm2;亚表层土壤有机碳储量提高（9.0~49.5）tC/hm2。采用不同施肥措施,土壤有机碳储量累积存在时段差异,不施肥耗竭种植条件下在试验初始5年碳储量缓慢下降,但在其后的18年中逐渐升高,因此在肥力水平较低土壤上,即使不施肥但长期耕作也将提高土壤碳储量,有利于贫瘠土壤固碳。这一结果也表明,若采用短期试验观测的数据不能全面反映人为管理措施对土壤碳储量的长期影响,对于碳储量的研究适宜依托长期观测试验的平台来完成。与不施肥或长期施用化肥相比,采用有机无机配施使灰漠土有机碳碳储量提高了32.1%~152.7%,固碳效应显著。将分层土壤容重考虑在内的等质量土壤碳储量计算方法能够较为客观评估秸秆还田的固碳效应。 相似文献
7.
本文基于土壤类型法,借助ArcGIS9.3工具,对珠江北江上游广东省翁源县的土壤表层有机碳储量及其时空分布进行了分析,并采用最大值法估算其主要土壤类型的有机碳增加潜力.结果显示,翁源县土壤表层平均有机碳密度与全国平均值接近,且近25a来略有下降趋势;水稻土表层有机碳密度上升幅度最大,“碳汇”效果明显;山地和旱地土壤表层表现出“碳源”的效应,水田则表现出“碳汇”的效应;土壤有机碳密度空间分布相对较高的是县域西北部和滃江流域;紫色土的固碳潜力最大,菜园地的固碳潜力最小,固碳潜力高值区主要位于漆江流域及其他耕地地区.在土壤类型和土地利用类型的基础上从时间和空间角度上分析翁源县土壤表层有机碳储量及固碳潜力,研究结果可以为区域农业生产活动、农业政策和碳平衡分析提供参考,同时对估算大尺度的土壤碳储量具有重要意义. 相似文献
8.
红壤丘陵区不同土地利用方式下有机碳储量的比较研究 总被引：20，自引：2，他引：20
以中国科学院千烟洲试验站为例，通过实测对比分析了红壤丘陵在开发14a后，不同土地利用方式下有机碳储量的变化。结果表明，在湿地从松和杉木林地系统中有机碳储量较高，主要储存于植物活体和凋落物；受人为活动干扰强烈的农田及人工草地系统有机碳储量较低，主要储存于土壤。土地利用方式对陆地生态系统碳循环有重要影响，调整土地利用方式成为人类调节大气含碳温室气体的一条重要途径。 相似文献
9.
通过对伊犁河谷地区四种典型土地利用类型（耕地,草地,园地和林地）0~60cm土层深度土壤有机碳含量与理化性质（速效氮、磷、钾,蔗糖酶活性,脲酶活性,过氧化氢酶活性）进行测定并分析土壤有机碳与理化性质的剖面分布特征及内在联系。结果表明：有机碳含量、速效氮、磷、钾、蔗糖酶、脲酶和过氧化氢酶的含量都随着土壤深度增加而降低。其中草地的有机碳含量、耕地的速效氮含量、园地的速效钾、速效磷含量、林地的蔗糖酶、脲酶、过氧化氢酶活性都高于其余三种土地利用方式。耕地的有机碳含量与速效氮、速效钾、速效磷和蔗糖酶活性在0.01水平上显著相关,园地的有机碳含量与速效氮、钾,脲酶和过氧化氢酶在0.01水平上显著相关,草地的有机碳含量与速效氮、磷、钾和两种酶活性（蔗糖酶和脲酶）呈极显著相关（P<0.01）,林地的有机碳含量与速效钾,脲酶和过氧化氢酶呈极显著相关（P<0.01）。 相似文献
10.
土壤类型对三江平原土地利用/覆被变化的影响 总被引：2，自引：0，他引：2
作为我国重要的粮食生产基地和淡水湿地集中分布区,三江平原对于保障国家粮食安全和区域生态安全具有举足轻重的地位。由于人类活动的剧烈影响,过去50年期间,三江平原土地利用/覆被发生了显著变化。本文在分析1954年～2005年三江平原土地利用/覆被变化过程的基础上,深入探索了土壤类型对土地利用/覆被变化过程的影响。结果表明,过去50余年中,三江平原土地利用/覆被变化剧烈,其中耕地增加了2.25倍,增加面积为385.55×104hm2。与耕地面积相对应的是湿地、林地和草地的大幅度减少,减少面积分别为256.72×104hm2、66.92×104hm2和57.65×104hm2。草甸土、白浆土、沼泽土、暗棕壤和黑土为土地利用变化最为剧烈的几种土壤类型,农业开垦活动和耕地面积的增加是研究区土地利用变化的主要特征和主导因素,湿地、林地和草地减少区域的土壤类型与耕地增加区域的主要土壤类型一致。三江平原耕地开垦对土壤类型的选择顺序为：草甸土、白浆土→沼泽土→暗棕壤。这一现象表明耕地开垦首先从自然条件相对优良的土壤资源草甸土、白浆土进行开发;随着草甸土和白浆土面积的迅速减少,沼泽土于1986年～1995年和1995年～2000年期间成为耕地开发最多的土壤类型;随着以上3种土壤类型中可开垦的土地资源减少,暗棕壤于2000年～2005年期间成为耕地开发最多的土壤类型。 相似文献
11.
《中国科学院院刊(英文版)》2008,22(1):2-3
CAS should stick to the principle of rendering service to, and giving impetus for, the development of China＇s science enterprise by making S＆T innovations, said CAS President LU Yongxiang. The CAS president made the remarks in a recent talk to communicate the gist of the winter session of the Party＇s Leading-member Group at CAS, which was held from 7 to 11 January in Beijing. 相似文献
12.
Marjorie Armstrong-Stassen Margaret Landstrom Ramona Lumpkin 《The Information Society》1998,14(2):153-164
This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors. 相似文献
13.
《中国科学院院刊(英文版)》2008,22(1)
With great care, Dr. ZHOU Zhonghe takes out a package wrapped by cotton tissue from a drawer and says: "This is the gem of our collections: the fossil of a bird that lived 125 million years ago!" Then, pointing at a tiny mound, he explains: "Look, this is the claw and that is the head. It was in the egg shell and ready to hatch ... The species fell into a family of waterside inhabitants." 相似文献
14.
A joint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology his co-workers from Norway US Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells suggesting that China's projected climate warming could decrease the pest's numbers. The study was published in Proceedings of the National Academy of Sciences on September .…… 《中国科学院院刊(英文版)》2008,22(1):6-7
Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China＇s projected climate warming could decrease the pest＇s numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007. 相似文献
15.
Caroline Haythornthwaite 《The Information Society》2001,17(3):211-226
A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction. 相似文献
16.
Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies. 相似文献
17.
Puay Tang 《The Information Society》1998,14(1):19-31
The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means. 相似文献
18.
Milton Mueller 《The Information Society》2001,17(3):151-163
Long-standing conflict between domain name registrants and trademark holders prompted the Internet Corporation for Assigned Names and Numbers (ICANN) to create a global, mandatory arbitration procedure known as the Uniform Dispute Resolution Policy (UDRP). The UDRP has been used in 2166 cases involving 3938 domain names as of 1 November 2000. The policy gives the initiator of a complaint, generally a trademark holder, the right to choose which ICANN-accredited dispute resolution service provider (RSP) will handle the case. During the preparation of the UDRP,some feared that complainant selection would lead to "forum shopping" that might bias the results. This article performs a statistical assessment of the forum-shopping thesis and finds support for it. There are statistically significant differences in the various RSPs' propensity to take away names from defendants; there are also major differences in the number of cases brought to each RSP. RSPs who take away names have the larger share of cases. The study examines other variables that might explain differences in market share, such as price, the plaintiff's nationality, or the time taken to decide a case. It finds that nationality and time also are correlated with market share. The study concludes that shopping for a favorable outcome is an important factor in the UDRP. 相似文献
19.
Prof. Raymond C.K. Chen a neuropsychologist with the CAS Institute of Psychology has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology.…… 《中国科学院院刊(英文版)》2008,22(1):15-15
Prof. Raymond C.K. Chen, a neuropsychologist with the CAS Institute of Psychology, has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology. 相似文献
20.
Prof. SUN Changpu from the CAS Institute of Theoretical Physics coworkers from University of Basel in Switzerland have worked out a way - at least in theory - to split a beam of molecules according to their chirality. The technique involves passing the molecules through three different laser beams is similar to the famous Stern-Gerlach effect whereby a beam of atoms passing through a magnetic field is split in two according to the atoms' spin states 《中国科学院院刊(英文版)》2008,22(1):23-23
Prof. SUN Changpu from the CAS Institute of Theoretical Physics and coworkers from University of Basel in Switzerland have worked out a way --at least in theory --to split a beam of molecules according to their chirality. The technique involves passing the molecules through three different laser beams and is similar to the famous Stern-Gerlach effect, whereby a beam of atoms passing through a magnetic field is split in two according to the atoms＇ spin states （Phys. Rev. Lett. 99 130403）. 相似文献