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Decades of commercial planting and other anthropogenic processes are posing a threat to the riparian landscapes of the Cauvery river basin, which supports a high floral diversity. Despite this, the habitats in the upstream sections of the River Cauvery are still intact, as they are located in sacred groves. To understand the dynamism of riparian forests exposed to anthropogenic pressures, the upstream stretch of Cauvery extending from Kushalanagara to Talacauvery (~102 km) was categorized into two landscapes: agro ecosystem and sacred (i.e. preserved). The tree species were sampled using belt transects at 5 km intervals and the regeneration status of endemic species assessed using quadrats. A total of 128 species belonging to 47 families, and representing 1,590 individuals, was observed. Amongst them, 65% of unique species were exclusive to sacred landscapes. A rarefaction plot confirmed higher species richness for the sacred compared to the agro ecosystem landscapes, and diversity indices with more evenness in distribution were evident in sacred landscapes. A significant loss of endemic tree species in the agro ecosystem landscapes was found. Overall, this study demonstrates that an intense biotic pressure in terms of plantations and other anthropogenic activities have altered the species composition of the riparian zone in non-sacred areas. A permanent policy implication is required for the conservation of riparian buffers to avoid further ecosystem degradation and loss of biodiversity. 相似文献
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农业气象灾害风险评价模型及应用 总被引：22，自引：3，他引：22
本文根据灾害风险分析原理，建立了一个经三层逐级放大的农业气象灾害风险分析实用模型，并以珠江三角洲荔枝生产为例分析计算了主要农业气象灾害以及风险体系的风险度，其结果对农业气象灾害风险管理与决策及灾害防御有一定的参考价值 相似文献
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气候变化对中国农业生产的影响 总被引：89，自引：1，他引：88
根据１９５８￣１９９７年中国３１０个气象站的月平均最高、最低气温,月平均降水量,日照时数等气象参数分析了中国气候的背影特征。用３个大气环流模型,即ＨａｄＣＭ２、ＣＧＣＭ１、ＥＣＨＡＭ４来模拟未来中国气候变化的情景。同时,建立未来气候变化的６种方案。最后,根据３个ＧＣＭｓ模拟的结果,利用国际应用系统分析研究所（ＩＩＡＳＡ）发展并改进的农业生态地带模型（ＡＥＺ）评估气候变化对中国农业生产的影响。评估主 相似文献
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北方农牧交错带的地理界定及其生态问题 总被引：121，自引：1，他引：121
我国北方农牧交错带主要分布于降水量300～450 mm，干燥度 1～2的内蒙古高原南缘和长城沿线，其东界和南界为黑龙江的龙江、安达，吉林的乾安和长岭，辽宁的康平、阜新，河北的丰宁、淮安，山西的浑源、五寨，陕西神木、榆林，甘肃环县，宁夏同心；其西界和北界为内蒙古的陈巴尔虎旗、乌兰浩特、林西、多伦、托克托、鄂托克和宁夏盐池。行政区划涉及 9省106个旗（县市），总面积654564km2。全区耕地总面积804.69万hm2，人均占有耕地 0.32hm2，农、林、牧用地比例为 1.0∶1.17∶3.67。主要生态问题为：沙漠化急剧发展、可利用土地资源锐减；草地退化、沙化、盐渍化严重，承载力急剧下降；生态环境恶化，自然灾害频繁。其原因除了受自然不利因素影响和现代人为强烈干扰外，还有沙漠化的历史烙印、现代农牧交错带的北移错位和经济地理三大原因。该区的退化生态治理应注意：大部分地区要逐步用榆、柳、松、杏等乡土树种取代高耗水肥的杨树树种，采取以灌木为主的乔灌草结合的带状造林方式，建立类似原生植被的人工疏林草原植被，充分发挥其生态屏障作用。农业应以发展灌溉农业和保护型农业为主攻方向，改变生产经营方式，大力提高生产水平、防止土地沙漠化。 相似文献
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农业生态系统的水热耗散过程与节水调控 总被引：3，自引：1，他引：2
华北平原广大的干旱、半干旱甚至半湿润区 ,水资源形势严峻 ,威胁农业持续发展。本文从近年来迅速发展的土壤—植物—大气连续体理论出发 ,论述了 SPAC过程与生态过程的联系与区分 ;在两个过程的联结点上衍生出水分利用率概念。讨论了界面的梯度驱动力 ,分析了水势驱动及其阻力 ,作物水分胁迫及反冲机制的诱导和增益 ,界面过程的高度非线性及其耦合。在此基础上提出水热传输界面调控与生态过程的机制调控相结合的理论与措施 ,以缓解水资源匮乏 ,提高持续生产力和水分利用效益 ;为实现农业持续发展 ,提供理论依据的实践途径。 相似文献
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Zinc remediation of aqueous streams is of special concern due to its highly toxic and persistent nature. Conventional treatment technologies for the removal of zinc are not economical and further generate huge quantity of toxic chemical sludge. Biosorption is emerging as a potential alternative to the existing conventional technologies for the removal of metal ions from aqueous solutions. Mechanisms involved in the biosorption process include chemisorption, complexation, adsorption–complexation on surface and pores, ion exchange, microprecipitation, heavy metal hydroxide condensation onto the bio surface, and surface adsorption. Biosorption largely depends on parameters such as pH, the initial metal ion concentration, biomass concentration, presence of various competitive metal ions in solution, and to a limited extent on temperature. Biosorption using biomass such as agricultural wastes, industrial residues, municipal solid waste, biosolids, food processing waste, aquatic plants, animal wastes, etc., is regarded as a cost‐effective technique for the treatment of high volume and low concentration complex wastewaters containing zinc metal. Very few reviews are available where readers can get an overview of the sorption capacities of agro based biomasses used for zinc remediation together with the traditional remediation methods. The purpose of this review article is to provide the scattered available information on various aspects of utilization of the agro based biomasses for zinc metal ions removal. An extensive table summarizes the sorption capacities of various adsorbents. These biosorbents can be modified using various methods for better efficiency and multiple reuses to enhance their applicability at industrial scale. We have incorporated most of the valuable available literature on zinc removal from waste water using agro based biomasses in this review. 相似文献
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