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21.
根据干旱草原区水资源承载系统具有数据多元性和动态性的特点,建立基于GIS的水资源承载能力模型,分别从时间和空间尺度上评价现状水资源承载能力及其影响因素,评价结果表明2008-2012年达茂旗全旗的水资源承载能力为一般水平,水资源承载能力较强水平的区域占全旗总面积的37.23%;降水的减少直接导致了生产、生态用水的下降。灵敏度分析结果表明水资源自身承载能力受水资源可利用比例影响最大,社会系统主要受人口密度、城镇化率影响,经济系统中,农业GDP比重影响很大。基于现状评价结果预设3种牧区用水方案优化模式,水资源承载能力预测结果表明水资源开发利用率控制效果并非越严格越好,节水型社会稳步建设方案是规划水平年牧区用水方案的适宜模式。 相似文献
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Environmental perceptions and practices of livestock keepers on the Namaqualand Commons challenge conventional rangeland management 总被引:1,自引:1,他引:1
Nicky Allsopp Catherine Laurent Laure M.C. Debeaudoin M. Igshaan Samuels 《Journal of Arid Environments》2007,70(4):740
In South Africa, interventions in communal rangelands proposed by most agriculture-sector institutions are still dominated by the belief that communal herders have little technical skills and by the tenets of “the tragedy of the Commons”, assuming that individual livestock keepers are selfish, norm free, and aiming at maximising short-term offtake and that there is no consistent management of the commons. In this study we show that practices of a diversity of livestock keepers on the Leliefontein Commons of Namaqualand are at odds with this viewpoint: access to rangeland and its use are structured by collective norms and concerns regarding both the sharing of resources and their long-term sustainability. We also show that part of the management of the commons relies on grazing practices which involve tacit and formalised technical knowledge that can be described and modelled. Livestock keepers assess the heterogeneity of the grazing quality of the commons. They are aware of the toxicity and unpalatability of some plants, of the way this differs according to the amount ingested and the availability of other forage, and of the variations of these two factors over seasons of grazing. They classify grazing areas and decide on daily grazing routes according to a complex set of criteria. Carrying capacity of each area is not considered as a fixed parameter but rather as a variable dependant on rainfall. Seasonal movements between areas are designed accordingly. These findings offer a new perspective for research agendas on technical models and extension measures for communal rangeland management particularly in arid and semi-arid areas. 相似文献
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利用多源气象要素数据估算了1998 - 2016年的藏北高寒牧区植被净初级生产力(Net Primary Productivity, NPP)的变化特征并预估了其在2 ℃全球变暖背景下的变化趋势, 结果表明: 研究区域71.9%的NPP呈上升趋势, 仅中部部分区域有下降趋势; 平均NPP以每年0.54%速率增加, 同期气温和降水均呈增加趋势, NPP和气温在2007前后有显著增加趋势; 总体来说降水是影响NPP的最主要气候因子, 且随着纬度升高其影响越来越大, 气温对于NPP的影响从东南向西北依次递减, 在西北地区出现弱的负相关; 在2 ℃全球变暖大背景下, 分析得出IPCC“典型浓度路径”(Representative Concentration Pathways, 简称RCPs)三种温室气体排放情景下(RCP2.6、 RCP4.5、 RCP8.5)的NPP平均状态几乎没有变化, 其影响仅限于对研究区东南部的较高NPP有较小的改善作用, 其作用依次为 , 表明气候变暖对研究区NPP影响有限, 预估结果对认清高原地区气候变化下NPP时空变化特征有重要意义。 相似文献
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气候变化对历史上农牧过渡带影响的个例研究 总被引:31,自引:6,他引:25
从北魏平城迁都、元朝中叶岭北地区移民、12世纪初科尔沁沙地演变、明初兀良哈三卫南迁等四个历史实例出发,讨论了气候变冷变干时,农牧过渡带变化以及相应的社会变化现象。可以肯定,气候变化对历史上农牧过渡带变迁的影响是存在的。同时气候变化对农牧过渡带的影响是通过人类社会系统起作用的,不同的社会状态和组合会产生不同的农牧过渡带实况和相应的社会问题。当农耕民族与游牧民族在农牧过渡带附近对峙时,气候向寒冷方向的变化常常成为社会动荡的触发因素,极端情况下可以产生很严重的后果。 相似文献
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中国北方农牧交错区土地荒漠化的环境脆弱性机制分析 总被引:24,自引:5,他引:19
在综合分析中国北方农牧交错区自然 、经济和社会环境的基础上,概括出导致该地带土地 荒漠化的生态环境脆弱性机制:①脆弱的自然条件奠定了特殊的地貌格局和脆弱的地表物质基础,受东亚季风影响的气候条件是土地荒漠化的自然驱动力。②人类不合理的经济活动是土地荒漠化的直接推动力。③不利的社会因素加快了土地荒漠化的进程。 相似文献
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气候变化对北方农牧交错带的可能影响 总被引:10,自引:2,他引:10
从可持续发展角度出发,分析了气候变化对北方农牧交错带的空间位置以及农牧业生产的可能影响。认为气候变化将使交错带向东南移动,气候变化对交错带农业的可持续发展不利,对牧业的可持续发展有利也有弊。 相似文献
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This paper investigates whether liveweight development of kids and dams can be improved by introducing a seasonal breeding regime in goat herds maintained under pastoral management in northern Kenya. The experimental treatment consisted of six consecutive mating seasons. Traits studied comprise relative growth rates of kids (g kg−0·75 day−1) from birth until 2 years of age, liveweight development of kids (kg) from birth until 2 years of age, and body weight development (kg) of does over a reproductive cycle of 1 year duration. No systematic effect of mating season on birth weights of kids could be detected, whereas the experiment succeeded in demonstrating that mating season has an impact upon body weight development of kids. The highest average preweaning weight gains were achieved by kids born in the period from October to May, while growth performance was seriously compromised when birth took place at the middle of the long dry season. However, the differences between mating season groups had almost completely disappeared by 1 year of age. The mating season treatment produced marked differences in weight development curves in does. During gestation, does were advantaged when they were mated just prior to the long rainy season, while the largest relative liveweight gains over the entire reproductive cycle were achieved by does mated during the short rains. It is concluded that seasonal breeding does not confer any major advantage in terms of liveweight production of young livestock, except that mating during the short dry season from December to January should be avoided. Similarly, a clear effect on body weights of does at the end of the reproductive cycle could only be observed when mating occurred during this period. 相似文献
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基于MOD13A3数据,建立2000-2017年甘南牧区植被覆盖时空数据集,分析了甘南牧区植被的时空分布及其变化特征,并利用同期气象数据探讨气象因子对其影响。结果表明,甘南牧区植被水平上呈南多北少的分布格局,与降水量分布基本一致;垂直分布上南部随海拔升高植被减少,北部随海拔升高植被增加。总体上,甘南牧区植被覆盖有增加趋势。气温、降水与日照时数是影响甘南牧区植被变化的重要因子,但2011年以后气温、降水及日照时数对植被变化的影响有所降低,其中5-6月降水量对亚高山草甸区植被变化的影响由显著正相关转为负相关。 相似文献