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Effect of competition on spatial patterns of oak forests on the Chinese Loess Plateau

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Journal of Arid Land 2017年第1期9卷 122-131页

作者： KANG Di DENG Jian QIN Xiaowei HAO Fei GUO Shujuan han xinhui YANG Gaihe College of Forestry Northwest A&F University Yangling 712100 China The Research Center of Recycle Agricultural Engineering and Technology of Shaanxi Province Yangling 712100 China College of Agronomy Northwest A&F University Yangling 712100 China Spice and Beverage Institute Research Chinese Academy of Tropical Agricultural Sciences Wanning 730070 China Yunnan Baiyao Group CO. LTD Kunming 650500 China

Reforestation or natural forest regeneration is an alternative measure for controlling soil erosion in degraded land on the Chinese Loess Plateau（CLP）. However, our understanding of the temporal dynamics and the spatial patterns of forest regeneration remains inadequate. Two oak forests at different development stages were investigated to determine the spatial patterns of competitions（intraspecies and interspecies） during different successional stages. The intraspecies and interspecies spatial relationships among different tree diameters at breast height were analyzed at multiple scales by Kriging interpolation method and univariate and bivariate O-ring statistics. Our analytical results indicated that self-correlation and competition intensity were relatively high between oak and pine trees in the early development stage of oak forests due to their clumped distributions of heavy seeds. Birch trees had a lower competition in comparison to oak trees although birch was the dominant species. Therefore, asymmetric competition of oak trees was most likely to have led to their edge dispersal and their success in replacing the pioneer species. Asymmetric competition means that larger individuals obtained a disproportionately large share of the resources and suppressed the growth of smaller individuals. Kriging interpolation analysis showed a tendency towards homogenization caused by interspecies competition during the succession of oak forests. Our results demonstrated that the competition was the driving factor in the spatial distribution of oak forests on the CLP.

关键词： arid and semi-arid region forest regeneration competition spatial pattern oak forests

Responses of plant community to the linkages in plant-soil C:N:P stoichiometry during secondary succession of abandoned farmlands,China

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Journal of Arid Land 2020年第2期12卷 215-226页

作者： LIU Weichao FU Shuyue YAN Shengji REN Chengjie WU Shaojun DENG Jian LI Boyong han xinhui YANG Gaihe College of Agronomy Northwest A&F UniversityYangling 712100China Research Center of Recycle Agricultural Engineering and Technology of Shaanxi Province Yangling 712100China School of Life Science Yan'an UniversityYan'an 716000China

Succession is one of the central themes of ecology;however,the relationship between aboveground plant communities and underground soils during secondary succession remains *** this study,we investigated the composition of plant community,plant-soil C:N:P stoichiometry and their relationships during secondary succession after the abandonment of farmlands for 0,10,20,30,40 and 50 a in China,*** showed that the composition of plant communities was most diverse in the farmlands after secondary succession for 20 and 50 *** organic carbon and total nitrogen contents slightly decreased after secondary succession for 30 a,but both were significantly higher than those of control farmland(31.21%-139.10%and 24.24%-121.21%,respectively).Moreover,C:N ratios of soil and microbe greatly contributed to the changes in plant community composition during secondary succession of abandoned farmlands,explaining 35.70%of the total ***,soil C:N ratio was significantly and positively related with the Shannon-Wiener *** study provides the evidence of synchronous evolution between plant community and soil during secondary succession and C:N ratio is an important linkage between them.

关键词： C:N ratio soil nutrient plant community restoration loess hilly region

Effect of Soil C,N and P Stoichiometry on Soil Organic C Fractions After Afforestation

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Pedosphere 2017年第4期27卷 705-713页

作者： ZHAO Fazhu ZhanG Lu SUN Jiao REN Chengjie han xinhui YANG Gaihe PANG Guowei BAI Hongying WANG Jun College of Urban and Environmental Sciences Northwest University Shaanxi Land Construction Group Shaanxi LCG Land Project Technology InstituteKey Laboratory of Degraded and Unused Land Consolidation Engineeringthe Ministry of Land and Resources of China Institute of Agricultural Resources and Environment Ningxia Academy of Agriculture and Forestry Sciences College of Agronomy Northwest A&F University

Afforestation is recognized as an important driving force for soil organic C(SOC) dynamics and soil element *** evaluate the relationships between soil C:N:P stoichiometry and SOC fractions,soil C:N:P stoichiometry distributions at 0–200 cm soil depths were analyzed and the contents of SOC fractions were evaluated in 9 typical land-use systems on the Loess Plateau of *** contents of light fraction organic C,particulate organic C(>53,53–2 000,and>2 000 μm),labile organic C,microbial biomass C,and dissolved organic C decreased with increasing soil depth and were higher in afforested soil than in slope cropland *** with the slope cropland,different vegetation types influenced soil C:N,C:P,and N:P ratios,especially when C:P and N:P ratios were significantly higher(Phanges in SOC fractions are largely driven by soil C:P and N:P ratios at different soil depths after afforestation.

关键词： dissolved organic C, labile organic C, light fraction organic C, microbial biomass C, particulate organic C

N-cycle gene abundance determination of N mineralization rate following re-afforestation in the Loess Plateau of China

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Soil Ecology Letters 2024年第1期6卷 97-106页

作者： Yaping Zhao Yuqing Zhao Shuohong Zhang Yulin Xu xinhui han Gaihe Yang Chengjie Ren College of Agronomy Northwest A&F UniversityYangling 712100China Shaanxi Engineering Research Center of Circular Agriculture College of AgronomyNorthwest A&F UniversityYangling 712100China

Afforestation effectively improved soil microbial communities and significantly increased soil nitro-gen mineralization rate(Rm).Soil microorganisms drive Rm by regulating soil N-cycling *** nitrification genes had a major effect on soil Rm than denitrification genes after *** the function of forest ecosystems requires an understanding of the mechanism of soil nitrogen ***,it remains unclear how soil N-cycling genes drive soil nitrogen mineralization during *** this study,we collected soil samples from a chrono-sequence of 14,20,30,and 45 years of Robinia pseudoacacia L.(RP14,RP20,RP30,and RP45)with a sloped farmland(FL)as a *** metagenomic sequencing analysis,we found significant changes in the diversity and composition of soil microbial communities involved in N-cycling along the afforestation time series,with afforestation effectively increasing the diversity(both alpha and beta diversity)of soil microbial *** conducted indoor culture experiments and analyzed correlations,which revealed a significant increase in both soil nitrification rate(Rn)and soil nitrogen mineralization rate(Rm)with increasing stand ***,we found a strong correlation between soil Rm and soil microbial diversity(both alpha and beta diversity)and with the abundance of soil N-cycling *** least squares path modeling(PLS-PM)analysis showed that nitrification genes(narH,narY,nxrB,narG,narZ,nxrA,hao,pmoC-amoC)and denitrification genes(norB,nosZ,nirK)had a greater direct effect on soil Rm compared to their effect on soil microbial *** results reveal the relationships between soil nitrogen mineralization rate and soil microbial communities and between the mineralization rate and functional genes involved in N-cycling,in the context of Robinia pseudoacacia *** on the Loess *** study enriches the understanding of the effects of microorganisms on soil nitrogen mineraliza

关键词： afforestation soil N mineralization rate denitrification genes nitrification genes the Loess Plateau

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会话初始化协议及其应用:现状、问题与展望

计算机工程 2005年第10期31卷 1-3页

作者：司端锋韩心慧龙勤潘爱民北京大学计算机科学技术研究所北京100871

会话初始化协议(SIP)是下一代网络中的核心协议之一。3G、网络控制、多媒体分发、网络电话、多媒体会议、即时消息、网络用具等方面的应用已初具规模。该文介绍了SIP的体系结构,给出了一个基本应用模型,针对其各个重要应用领域的现状进... 详细信息

会话初始化协议(SIP)是下一代网络中的核心协议之一。3G、网络控制、多媒体分发、网络电话、多媒体会议、即时消息、网络用具等方面的应用已初具规模。该文介绍了SIP的体系结构,给出了一个基本应用模型,针对其各个重要应用领域的现状进行了评述,并指出了目前存在的问题和今后的发展方向。

关键词：会话初始化协议 SIP应用多媒体通信

一种基于丢包依赖体现的E模型的自适应播放延迟算法

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北京大学学报（自然科学版） 2006年第3期42卷 388-394页

作者：韩心慧司端锋邹维北京大学计算机科学技术研究所北京100871

在Internet通信播放延迟算法的基础上,使用E模型作为分析工具,并考虑丢包依赖在E模型中的体现以及对用户语音感受的影响,提出了一种应用于多方实时通信领域的新的自适应播放延迟算法,使得用户终端在获得良好Internet通信参数的同时,进... 详细信息

在Internet通信播放延迟算法的基础上,使用E模型作为分析工具,并考虑丢包依赖在E模型中的体现以及对用户语音感受的影响,提出了一种应用于多方实时通信领域的新的自适应播放延迟算法,使得用户终端在获得良好Internet通信参数的同时,进一步提升用户的语音感受。实验测试结果发现,这种算法相比于目前其他算法,在丢包率、延迟等方面都有显著的改善,同时能够降低系统的连续丢包现象。

关键词：多方实时通信自适应播放延迟算法丢包依赖 E模型

黄土丘陵区退耕还林土壤不同大小颗粒固碳过程与速率

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农业机械学报 2016年第8期47卷 117-124页

作者：佟小刚韩新辉李娇马建业西北农林科技大学资源环境学院陕西杨凌712100 农业部西北植物营养与农业环境研究重点实验室陕西杨凌712100 西北农林科技大学农学院陕西杨凌712100

为揭示黄土丘陵区退耕还林土壤固碳过程及其变化机制,采用物理分组法探讨了安塞纸坊沟退耕15~45 a刺槐与柠条林地土壤砂粒、粉粒、黏粒截存有机碳的效应与速率。结果表明,对比坡耕地,两种退耕林地土壤颗粒结合碳含量均随退耕年限延长显... 详细信息

为揭示黄土丘陵区退耕还林土壤固碳过程及其变化机制,采用物理分组法探讨了安塞纸坊沟退耕15~45 a刺槐与柠条林地土壤砂粒、粉粒、黏粒截存有机碳的效应与速率。结果表明,对比坡耕地,两种退耕林地土壤颗粒结合碳含量均随退耕年限延长显著增加,并且表层0~10 cm土壤增幅最高,10~60 cm各土层增幅基本接近。退耕15~45 a期间,刺槐与柠条林0~20 cm土层均以粉粒碳密度增速最高,分别达0.21、0.11 Mg/（hm2·a）,砂粒碳和黏粒碳增速相近,平均分别为0.13、0.06 Mg/（hm2·a）。同样的变化发生在0~60 cm土层,但各颗粒碳密度增速为0~20 cm土层的1.6~2.5倍。按此增速到退耕45 a时柠条林地砂粒碳、粉粒碳、黏粒碳相比坡耕地分别增大了2.6、1.1、0.8倍,刺槐林地则分别增大了8.3、2.2、2.8倍,并且对总有机碳累积贡献的平均比率为：砂粒碳（23%）等于黏粒碳（26%）且均小于粉粒碳（51%）。此外碳库管理指数比碳库活度与土壤总有机碳库变化有更显著的线性相关性。综上分析,该区域退耕刺槐林比柠条林土壤有更强的固碳效应,两种林地均以粉粒碳为主要固碳组分,以砂粒碳周转速率最快。

关键词：黄土丘陵区退耕还林土壤有机碳土壤颗粒固碳

支持加壳应用的Android非侵入式重打包方法研究

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北京大学学报（自然科学版） 2018年第6期54卷 1147-1158页

作者：黎桐辛韩心慧简容肖建国北京大学计算机科学技术研究所北京100871 北京航空航天大学北京100083

通过分析Android的应用特点,提出一种新的Android重打包方法。该方法可以在不反编译、不修改原有应用代码的基础上,实现对Android应用的重打包,并支持主流加壳工具。该方法利用多种新的代码注入技术,引入额外代码;加载Hook框架,提供代... 详细信息

通过分析Android的应用特点,提出一种新的Android重打包方法。该方法可以在不反编译、不修改原有应用代码的基础上,实现对Android应用的重打包,并支持主流加壳工具。该方法利用多种新的代码注入技术,引入额外代码;加载Hook框架,提供代码修改能力;最后动态修改应用行为,实现应用重打包。实现了原型框架,并通过实验,验证了该框架在多个Android系统版本及多个加壳服务上的有效性。既证明了现有加壳技术的缺陷,又可以用于对Android应用的动态调试、防御功能部署以及应用修改等。

关键词： Android 重打包非侵入式加壳

二进制程序中的use-after-free漏洞检测技术

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清华大学学报（自然科学版） 2017年第10期57卷 1022-1029页

作者：韩心慧魏爽叶佳奕张超叶志远北京大学计算机科学技术研究所北京100080 清华大学网络科学与网络空间研究院北京100084

Use-after-free漏洞(简称UaF漏洞)是当前最流行的高危内存破坏漏洞。目前针对UaF漏洞的检测工作并不完善,原因是UaF漏洞产生的特征是分配内存、释放内存、使用已释放的内存并按顺序出现,而这3种事件可能出现在程序的任何位置,需要跟踪... 详细信息

Use-after-free漏洞(简称UaF漏洞)是当前最流行的高危内存破坏漏洞。目前针对UaF漏洞的检测工作并不完善,原因是UaF漏洞产生的特征是分配内存、释放内存、使用已释放的内存并按顺序出现,而这3种事件可能出现在程序的任何位置,需要跟踪较长的执行序列并搜索潜在的危险事件序列才能检测到该漏洞,这很大程度上提高了检测的难度。该文针对UaF漏洞,分析了漏洞的产生原因、利用方式、带来的安全威胁以及漏洞检测技术面临的挑战,并设计和实现了一个基于静态分析和动态符号执行的面向二进制文件的UaF漏洞检测系统。经测试,该系统能够检测出已公开的UaF漏洞。通过该系统检测软件中的UaF漏洞,及时对软件进行修复或防护,可以有效提高软件的健壮性,减少UaF漏洞带来的安全隐患。

关键词： use-after-free 静态分析动态符号执行