气候变化对非洲水资源和农业的影响

尽管非洲是世界上温室气体排放总量或人均排放量最少的地区,但在承受气候变化造成的恶劣影响方面首当其冲。气候变化已经给非洲的水资源、农业、生物多样性、人类健康和国家安全等带来诸多严重影响,粮食生产和水资源一直是非洲长期面临的两大难题,也是深受气候变化影响的两大领域还较欠缺,需要在未来的研究中进一步加强,以探寻减缓气候变化对非洲水资源和农业不利影响的有效途径。本文系统梳理了气候变化对非洲水资源系统和农业生产影响的研究成果和不足,以期为非洲气候变化影响评估工作提供一定参考和借鉴。已有的观测结果表明,气候变化导致非洲许多山脉冰川面积正在大范围缩减、大部分地区降水量有所减少,降雨的年际间分布也更为不稳定,通过水文模型的模拟预测,未来气候变化将进一步影响降水量和非洲部分地区河流的径流量,导致非洲水资源供给压力加大。同样,气候变化也给非洲农业生产带来了巨大的挑战,无论是观测结果分析,还是统计模型和作物模型等对不同气候情景和时间尺度下非洲农业的模拟研究,都显示气候变化对非洲农业以负面影响为主,导致非洲干旱加剧、生长季改变和粮食产量下降,并可能危及非洲的粮食安全。然而,现有研究结果还存在较多不确定性,其主要集中在未来气候情景数据、研究方法、数据的质量和数量等方面。与世界其它地区相比,非洲气候变化影响研究无论是研究的深度和广度都     

非洲鸵鸟食管组织学观察

应用常规石蜡切片,H—E染色,对非洲鸵鸟食管组织结构进行观察并与家禽和哺乳动物的食管进行比较．结果表明：非洲鸵鸟食管黏膜上皮为复层扁平上皮,但角质化不明显,固有膜内食管腺丰富,由腺细胞围成的管泡状腺直接开口于黏膜上皮,分泌大量黏液．食管肌层非常发达,分为内环肌、中纵肌、外环肌3层,环肌很厚,与纵肌的比例约为3：1、外膜是一层薄的纤维膜,内含丰富的血管．淋巴组织和神经.     

Land degradation assessment in Southern Africa: integrating local and scientific knowledge bases

Recent attempts to address land degradation have seen calls for greater integration of scientific expertise with local knowledges. In this paper we investigate the potential for such combined understandings to enhance the accuracy, coverage and relevance of land degradation assessment. We followed a participatory approach, using methods from a variety of disciplines, to elicit potential land degradation indicators from communities in Botswana and Swaziland. These indicators were then assessed according to local and scientific understandings. We noted a significant overlap between scientific and local knowledges about land degradation in most instances. Where discrepancies occurred, the integrated participatory approach we used allows appropriate explanation to be reached, supporting the case that such an iterative process can lead to both accurate and relevant monitoring of land degradation. However, the incorporation of integrated knowledges into national policy has not been widespread in either country, suggesting that much greater efforts are required to institutionalise participatory land degradation assessment methodologies. Powerful, often neo‐Malthusian narratives of degradation continue to dominate policy discourse and limit the extent to which hybrid combined local and scientific knowledges can enhance land degradation assessment on a national and regional scale. Copyright © 2006 John Wiley & Sons, Ltd.     

Adoption decision and use intensity of soil and water conservation measures by smallholder subsistence farmers in Dedo District,Western Ethiopia

Soil degradation in the highlands of Ethiopia is a serious problem that threatens the sustainability of agriculture. Although efforts have been made to develop and promote several soil conservation technologies, their adoption has not been widespread. This study, based on responses from a sample of 101 households which operate on 204 plots in Western Ethiopia, interviewed in 2003 cropping year, employed a Tobit model to identify the main factors influencing farmers' decision to adopt and intensify the use of improved and indigenous soil and water conservation (SWC) measures. The results suggest that area of cultivated land, land/labour ratio, age and education level of household head and distance of the plot from home and slope of the plot provided statistically adequate predictive power on the use and intensity of SWC measures. These results are discussed and their implications for conservation programs are presented in the conclusion. Copyright © 2006 John Wiley & Sons, Ltd.     

Short-season cotton (Gossypium hirsutum) may be a suitable response to late planting in sub-Saharan regions

In Cameroon, seed cotton yields have not increased over the last 20 years because of the shortening of the rainy season and the worsening socioeconomic context. Farmers consequently often delay planting their crops. The main objective of this study was to investigate whether local indeterminate long-season cottons, grown at the recommended density, were more consistent with the farmers’ current constraints than determinate short-season cultivars from Latin America that could be sown more densely. We carried out a 3-year three-location survey in northern Cameroon, which included two planting dates (recommended and delayed) and two planting densities (recommended and high). We show that these three factors acted independently. Late planting had a highly negative impact on most traits at both plant and plot scale by delaying flowering, reducing seed cotton yield and fibre quality. Dense sowing mainly had an impact on individual plant traits by reducing boll retention and elongating main-stem internodes. Local cultivars have already evolved favourably (enhanced earliness, yield performance, harvest index, ginning out-turn, and fibre maturity) and could be improved further by crossing with highly determinate cottons. However, such a strategy requires further investigation to ensure that a more determinate growth pattern would not have a negative impact on the adaptive response of the traditional cotton plant to other adverse conditions.     

我国援非农业技术示范中心可持续发展战略初探

自2006年11月中非合作论坛北京峰会后,中国援非农业技术示范中心工程项目相继竣工。国家将对示范中心提供建成后头3年的运行经费,之后将以企业运行方式实现可持续发展。充分认识和利用当地的自然资源、引入精耕细作种植模式、解决非洲粮食危机、关注小农利益、授人以渔及加强交流等是未来实现示范中心可持续发展的重要方法。     

非洲香蕉和大蕉产销概况

非洲是全球重要的香蕉和大蕉产出地。2009年非洲香蕉总产约为世界的12.6%;大蕉总产约为世界的81%。两者合计非洲香蕉和大蕉总产约为世界的28%。尤其在非洲撒哈拉边缘,大蕉占了当地大约1亿居民主食的四分之一。非洲香蕉和大蕉主生产区主要分布在非洲东部、西部和中部。东部非洲各国香蕉总产大约为780万t,平均每公顷香蕉产出...     

全球水稻生产现状与制约因素分析

【目的】分析全球水稻生产现状及其制约水稻生产的主要因子,探讨提高水稻产量的主要途径。【方法】采用全球水稻生产资料定量分析水稻面积和单产变化及其对总产贡献,及制约水稻生产的主要因素。【结果】全球水稻生产自1961年至2006年,由于复种指数提高,面积增长32%,年均增长0.61%。单产提高1.21倍,年均增长1.82%,单产提高主要依靠矮杆品种和杂交稻及其配套栽培技术的推广,灌溉设施改善和化肥施用。总产增长1.92倍,年均增长2.46%。水稻总产增长中,由面积增长贡献27%,由单产提高贡献73%。20世纪60年代以来全球水稻面积年增长率呈现逐年下降趋势。近年来水稻单产的增长率逐年变小,20世纪80、90年代和2000年以来分别为2.58%、0.98%和1.16%。面积下降和单产增长率变小导致总产增长率下降,20世纪80、90年代和2000年以来总产年均增产率分别为2.73%、1.48%和0.88%。制约水稻生产的主要因子是,水稻生产技术对单产提高的贡献率下降,病虫草危害及自然灾害频繁,多熟制生产系统水稻单产下降,水稻生产效益低。【结论】提高水稻产量的主要技术对策是改良水稻品种和扩大杂交稻应用,在非洲推进非洲新水稻应用,推广水稻集成栽培技术弥合水稻产量差异,发展水稻机械化生产技术及政府加大对水稻生产的政策支持。     

3个南非耐旱引进树种在云南省的生长适应性初步研究

引进南非干热逆境地区的Acacia karoo、Acacia nilotica、Albizia adiolutica 3个含羞草科(MIMOSACEAE)树种在云南进行生长适应性研究结果表明,在各试验点生长保存情况各自不同.在3个试验点,Acacia karoo生长都优于其他2个树种,Albizia adiolutica生长都较差.此外,3个树种在3个代表云南省不同气候的试验点的生长与试验点关键气候因子的相关性分析表明,3个树种都对炎热干燥的气候有明显的适应性,而不适宜种植在降雨丰富和湿度较大的地区.