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71.
Alternative land management practices, including agroforestry, help to maintain levels of soil organic matter (SOM) and can facilitate soil carbon (C) sequestration for mitigating atmospheric CO2 emissions. This study quantified C inputs and determined the changes of the soil C pool in a 19-year-old Gliricidia sepium alley cropping system, studied at two fertiliser levels (tree prunings only [? N], and tree prunings plus chicken manure [+ N]), and was compared to a sole crop system. Carbon input from tree prunings ranged from 455 to 457 g C m? 2 y? 1, whereas C inputs from crop residues were similar between alley- and sole crops ranging from 121 to 159 g C m? 2y? 1. The soil organic C (SOC) pool in the alley crop was 16–23% higher than the sole crop. In the 19th year of alley farming, SOC was significantly higher (p < 0.05) in the alley crop (3.2%) compared to the sole crop (2.4%), and was also greater compared to that at the time of establishment of the agroforestry system (2.8%). Gross SOC turnover to a 20-cm depth ranged from 12 to 14 years in the + N and ?N alley crops compared to 49 and 50 years in the + N and ?N treatments for the sole crops. Residue stabilisation efficiency in the alley crops was 39% and 55% in + N and ?N treatments respectively. 相似文献
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ABSTRACT Performance-based research evaluations have been adopted in several countries both to measure research quality in higher education institutions and as a basis for the allocation of funding across institutions. Much attention has been given to evaluating whether such schemes have increased the quality and quantity of research. This paper examines whether the introduction of the New Zealand Performance-Based Research Fund process produced convergence or divergence in measured research quality across universities and disciplines between the 2003 and 2012 assessments. Two convergence measures are obtained. One, referred to as β-convergence, relates to the relationship between changes in average quality and the initial quality level. The second concept, referred to as σ-convergence, relates to the changes in the dispersion in average research quality over time. Average quality scores by discipline and university were obtained from individual researcher data, revealing substantial β- and σ-convergence in research quality over the period. The hypothesis of uniform rates of convergence across almost all universities and disciplines is supported. The results provide insights into the incentives created by performance-based funding schemes. 相似文献
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This article examines the organisational barriers to successful implementation of information technology in the hotel industry. These are barriers of will, ability, and finance which block the routes to integration of internal systems. 相似文献
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针对直升机卫星通信系统中直升机旋翼对通信信道造成的周期性衰落问题,采用射频收发器AD9361模拟了信道周期性衰落模型,基于此模型在现场可编程门阵列(Field Programmable Gate Array,FPGA)上优化并实现了缝隙检测算法。根据信道衰落模型和缝隙检测算法及数据链路速率和带宽的要求,提出了一套直升机卫星通信系统可靠通信方案,即前向链路采用重发和分集接收及短码LDPC编码技术,返向链路根据前向链路缝隙检测的结果在无遮挡缝隙采用突发通信和长码低密度奇偶校验(Low Density Parity Check,LDPC)编码技术,实现可靠通信。系统测试结果表明,该方案不受直升机机型限制,系统可在40%遮挡率下实现前向链路25.6 kb/s和返向链路4 Mb/s速率下的可靠通信。 相似文献
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研究目的:剖析“双碳”目标与全域土地综合整治的互馈关系,解析全域土地综合整治减排增汇的内涵特征、机理和路径,为“双碳”目标背景下全域土地综合整治规划和实施方案的优化提供科技支撑。研究方法:文献资料法和归纳演绎法。研究结果:(1)“双碳”目标赋予了全域土地综合整治减排增汇的新时代生态要义,而全域土地综合整治可以赋能“双碳”目标的实现,二者具有相辅相成的互馈关系。(2)全域土地综合整治系统内涵体现为通过培育多元主体低碳理念,在低碳化整治工程的基础上,优化国土空间碳源/碳汇格局,推动产业活动低碳转型。(3)全域土地综合整治减排增汇过程形成了多要素综合作用的“外缘—内核式”复杂系统,“社会—经济—生态”外缘系统发挥支撑和约束作用,内核系统实现“人—地—业”的协同发展,外缘内核之间双轮耦合,系统推进。(4)最后通过强化“双碳”目标在“社会—经济—生态”外缘系统中的约束作用,构建 “人—地—业”内核系统的减排增汇实施路径。研究结论:全域土地综合整治的减排增汇路径探索是响应“双碳”目标的时代所趋,需要结合内外部环境统筹推进,破解乡村系统实现“双碳”目标的现实压力,助推美丽乡村和生态文明建设。 相似文献
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