The potential for soil carbon sequestration in three tropical dryland farming systems of Africa and Latin America: A modelling approach

Historically, agriculturally induced CO₂ release from soils has contributed to rising levels in the atmosphere. However, by using appropriate management, soils can be turned into carbon sinks. Many of the dryland regions of the world are characterised by degraded soils, a high incidence of poverty and a low capacity to invest in agriculture. Two well-proven soil organic matter models (CENTURY 4.0 and RothC-26 3) were used two explore the effects of modifying agricultural practices to increase soil carbon stocks. The changes to land management were chosen to avoid any significant increase in energy input whilst using technologies that would be available without radically altering the current agricultural methodology. Case studies were selected from dryland farming systems in Nigeria, Sudan and Argentina. Modelling showed that it would be possible to make alterations within the structure of the current farming systems to convert these soils from carbon sources to net sinks. Annual rates of carbon sequestration in the range 0.08–0.17 Mg ha⁻¹ year⁻¹ averaged over the next 50 years could be obtained. The most effective practices were those that maximised the input of organic matter, particularly farmyard manure (up to 0.09 Mg ha⁻¹ year⁻¹), maintaining trees (up to 0.15 Mg ha⁻¹ year⁻¹) and adopting zero tillage (up to 0.04 Mg ha⁻¹ year⁻¹). Verification of these predictions will require experimental data collected from field studies.     

坑状浅沟侵蚀研究

坑状浅沟作为浅沟与切沟的中间过程，深入理解它对于进一步认识切沟侵蚀规律具有十分重要的意义，但是还没有见到相关的研究报道。以内蒙古高原的一个小流域为例。利用高精度的全球定位系统（GPS）测量坑状浅沟侵蚀的形态参数，探讨了坑状浅沟的相关特征，分析了坑状浅沟的坡度（S）和上有集水区面积（A）的关系（S—A）、侵蚀体积（V）和长度（L）的关系（V-L），以期能推动坑状浅沟侵蚀的研究。     

东北农牧交错带旱涝特征对气候变化的响应

[目的]从旱涝灾害角度分析气候变化对东北农牧交错带的影响,对该区的气候变化和旱涝特征进行研究,为充分利用气候资源,合理调配水资源,提高灾害应变能力提供科学依据。[方法]统计1960—2011年东北农牧交错带21个气象台站的逐月气温、降水资料,应用Mann—Kendall气候突变检验法、标准化降水指数(SPI)、样条函数插值法对该带旱涝状况的时空分布进行了分析。[结果](1)东北农牧交错带气候呈现出明显的暖干化趋势,SPI3表明春、夏、秋三季干旱事件增多,21世纪以来,春旱事件较为频繁,冬季降水略微增加;(2)气温突变发生在1988年,突变后,干旱的比例增加了20.7%,涝的比例增加了9.3%,降水处于"正常"的年份则大幅度减少,对该区极为不利;(3)SPI12低值中心由科尔沁沙地向东北延伸到松嫩平原,干旱面积有大幅度增加的趋势,东北农牧交错带中南部旱化较为严重。[结论]东北农牧交错带暖干化的趋势给该区农牧业带来不利影响,受旱地区应及时启动干旱预警紧急方案,开展抗旱工作。     

Structural characteristics of a low Arctic tundra ecosystem and the retreat of the Arctic fox

We conducted a large-scale, campaign-based survey in Finnmark, northern Norway to evaluate the proposition that declining Arctic fox populations at the southern margin of the Arctic tundra biome result from fundamental changes in the state of the ecosystem due to climatic warming. We utilized the fact that the decline of the Arctic fox in Finnmark has been spatially heterogeneous by contrasting ecosystem state variables between regions and landscape areas (within regions) with and without recent Arctic fox breeding.Within the region of Varanger peninsula, which has the highest number of recorded dens and the most recent breeding records of Arctic fox, we found patterns largely consistent with a previously proposed climate-induced, bottom-up trophic cascade that may exclude the Arctic fox from tundra. Landscape areas surrounding dens without recent Arctic breeding were here more productive than areas with recent breeding in terms of biomass of palatable and climate sensitive plants, the number of insectivorous passerines and predatory skuas. Even the frequency of unspecified fox scats was the highest in landscape areas where arctic fox breeding has ceased, consistent with an invasion of the competitively dominant red fox. The comparisons made at the regional level were not consistent with the results within the Varanger region, possibly due to different causal factors or to deficiencies in Arctic fox monitoring at a large spatial scale. Thus long-term studies and adequate monitoring schemes with a large-scale design needs to be initiated to better elucidate the link between climate, food web dynamics and their relations to Arctic and red foxes.     

Potential effects of global warming on northern European freshwater fish and fisheries

Abstract Global warming is expected to result in considerable changes in northern European freshwater fish populations, fisheries and aquaculture. Shifts towards cyprinid and percid dominance in fish assemblages are expected, together with a decrease and collapse of salmonid and other coldwater fish populations. Most of the evident changes will occur in shallow lakes, where no thermal stratification occurs. The potential ranges of some fish species will shift northwards but pronounced changes will occur in the relative abundance of individual fish species. Total fish production will increase but because of changed composition of fish communities the commercial and recreational value of catches will decrease. Salmonid aquaculture productivity will increase provided that fish farmers adapt to new circumstances and cold, oxygenated water is available in larger quantities during summer.     

北方运动场草坪冬季加热保温技术的研究

冬季对北方运动场草坪进行了加热保温技术处理 ,结果表明 :增温保绿效果显著 (P <0 .0 1) ,在冬季 (12月至 2月初 )各处理草坪地表温度比大气温度平均高 6～ 9℃。水加热 (太阳能集热器 ) +覆膜 (塑料薄膜 )处理增温保绿效果较好 ,其次是单一覆膜处理 ,而电加热 (地热线 ) +覆膜处理增温保绿效果较差。每周揭膜 (8～ 2 0h) 1次保温最好 ,而每日揭膜 1次不利于温度的积累。单一覆膜处理经济有效 ,简单易行 ,投资后的使用成本仅为 4 .90元 /m2 ,应是北方运动场草坪冬季加热保温技术中的首选方法。水加热 (太阳能 ) +覆膜技术处理虽增温保绿效果好 ,但投资后的使用成本较高 ,为 14.6 9元 /m2 ;电加热 +覆膜处理投资后的使用成本为 8.97元 /m2 。冬季对草坪采用加热保温技术处理后 ,草坪早春生长优势明显 ,且未对以后季节草坪草的生长造成不利影响。     

气候变暖对邢台市小麦病虫发生规律的影响及其对策

分析了邢台市近年来气温上升对小麦病虫害发生规律及危害的影响,并提出了应对气候变暖、预防和减轻小麦病虫危害的对策:建立和完善小麦病虫害监测预警机制;提高小麦病虫害综合防治的技术水平。     

辽宁省育肥猪生产环境影响的生命周期评价

采用生命周期评价方法,以1000头出栏育肥猪的规模化养殖场为功能单位,对辽宁地区育肥猪生产进行污染物排放清单分析,评价其环境影响。结果表明,1000头育肥猪生产的生命周期环境影响综合指数为56.59,环境影响大小依次为富营养化、酸化、全球变暖,环境影响指数依次为36.31、13.84和6.44;富营养化影响主要来源于猪粪尿中氮、磷的排放,酸化影响主要来源于猪粪尿中NH3的排放,全球变暖影响主要来源于种植饲料作物使用的化肥生产过程中NOx的排放。因此,加强养猪粪污无害化处理,促进养殖业废物资源化,增加育肥猪饲料中青饲料比例,提高饲料作物生产过程中化肥利用率是降低辽宁地区育肥猪生产环境负荷的主要措施。     

湿地氮循环过程及其研究进展

从湿地氮循环的主要研究对象和基本研究方法出发,讨论了同位素方法在氮循环研究中的应用,总结了氮同位素用于研究湿地系统的生物地球化学过程以及各形态氮的迁移转化等方面的应用实例,并对湿地氮循环同位素及其相关技术方法的发展趋向进行了展望,最后归纳提出了氮同位素在我国湿地生态系统氮循环研究中的不足及未来的发展方向。