The Effects of Climate Change on the Planting Boundary and Potential Yield for Different Rice Cropping Systems in Southern China

Based on climate data from 254 meteorological stations, this study estimated the effects of climate change on rice planting boundaries and potential yields in the southern China during 1951-2010. The results indicated a signiifcant northward shift and westward expansion of northern boundaries for rice planting in the southern China. Compared with the period of 1951-1980, the average temperature during rice growing season in the period of 1981-2010 increased by 0.4＆#176;C, and the northern planting boundaries for single rice cropping system （SRCS）, early triple cropping rice system （ETCRS）, medium triple cropping rice system （MTCRS）, and late triple cropping rice system （LTCRS） moved northward by 10, 30, 52 and 66 km, respectively. In addition, compared with the period of 1951-1980, the suitable planting area for SRCS was reduced by 11%during the period of 1981-2010. However, the suitable planting areas for other rice cropping systems increased, with the increasing amplitude of 3, 8, and 10%for ETCRS, MTCRS and LTCRS, respectively. In general, the light and temperature potential productivity of rice decreased by 2.5%. Without considering the change of rice cultivars, the northern planting boundaries for different rice cropping systems showed a northward shift tendency. Climate change resulted in decrease of per unit area yield for SRCS and the annual average yields of ETCRS and LTCRS. Nevertheless, the overall rice production in the entire research area showed a decreasing trend even with the increasing trend of annual average yield for MTCRS.     

河北省三大棉区气候周期及突变特征分析

利用河北省棉区1961—2010年15个站点逐日气象资料,分析了河北省不同棉区气候周期振荡及突变点,结果表明：不同棉区棉花全生育期气温、降水、日照均存在多个时间尺度的周期变化特征,交替现象明显;全生育期平均气温年代际以及年际主要周期：冀南、冀中棉区为20～22 a、9～10 a、5～7 a,冀东棉区为22～24 a、11～14 a,全生育期平均气温升高明显,在1996年发生了突变,转入气温相对较高期。全生育期降水主要周期：冀南棉区为14～15 a,冀中、冀东棉区为22～24 a、8～10 a。全生育期日照存在9～10 a振荡周期,且1986年前后发生突变,转入相对偏少期。     

粮食主产区农户种粮意愿及影响因素分析———基于黑龙江省种粮农户的调查

新经济形势下,粮食安全特别是主产区的粮食安全供给关系到了整个国内粮食的稳定.采用黑龙江省265份种粮农户的调查数据,运用Logistic模型对黑龙江省农户种粮意愿影响因素进行实证分析.结果表明:种粮收益、生产灌溉水资源充足与否、粮食补贴政策、粮食销售交通便利性、生产资料价格合理性与农户种粮意愿呈正相关关系,非农收入比例与种粮意愿呈负相关关系.在此基础上提出,加强主产区农户粮食生产各项政策补贴,增加其种粮收益;改善主产区粮食生产基础设施条件,保障农田水利、道路交通等设施的政府投入力度;积极培育专业化种粮大户或家庭农场,集中有限的资源扩大其规模经营效益;深入探讨主产区承包经营体制,稳定推进种粮农户粮食生产投入.     

老哈河流域不同气候区间天然植被的实际蒸散发量研究

本文基于PM公式,结合LAI数据,考虑冠层截留雨水的蒸发量,针对老哈河流域不同气候区条件,对天然植被进行了实际蒸散发量的测算.比较了在不同气候区条件下,天然植被蒸散发量的差异.结果表明:老哈河流域天然林地的实际蒸散发量明显要大于天然草地的实际蒸散发量.考虑土壤水分条件下,流域内不同气候区间的实际蒸散发量差异并不大,其中土壤水分含量是影响天然植被实际蒸散发量的重要因素.老哈河流域天然草地普遍存在土壤水分胁迫现象,需要在缺水时段,对天然植被进行人工补水,从而维持生态系统的稳定.     

祁连山青海云杉径向生长对气候的响应

为探明树木径向生长对气候变化的响应,以祁连山中部下限青海云杉为研究对象,采用年表气候相关分析和特征年分析方法,研究了青海云杉的年轮宽度、早材宽度、晚材宽度标准化年表与月均温度和降雨量的关系。结果表明:年轮宽度、早材宽度、晚材宽度与6、7月的月均温度显著负相关。年轮宽度、早材宽度与3、5、6月的降雨量显著正相关,与9月的降雨量显著负相关;晚材宽度与降雨量无显著相关,晚材宽度对气候的敏感性弱于早材宽度。特征年分析进一步发现:当夏季温度高于同期温度而夏季降雨量又低于同期降雨量时,容易形成窄年轮;相反,当夏季温度低于同期温度而夏季降雨量又高于同期降雨量时,容易形成宽年轮。表明春季和夏季降雨量对祁连山中部下限青海云杉的径向生长有促进作用,而夏季温度有抑制作用。      

半干旱牧区天然打草场生产力时空变化及对气候响应分析

【目的】定量评估半干旱牧区天然打草场的生产能力,分析天然打草场的退化程度,明确气候因子对打草场生长过程的影响。【方法】利用Miami和Tharnthwaite Memorial模型计算2000—2017年半干旱牧区天然打草场气候生产潜力,并结合近18年的中分辨率成像光谱仪(MODIS)净初级生产力(NPP)产品(MOD17A2H)进行分析。【结果】2000—2017年半干旱牧区天然打草场实际生产力与潜在生产力均随降水增加呈上升趋势,天然打草场18年平均实际生产力和潜在生产力分别为295.24和557.79 g C·m^-2·a^-1。按不同草地类型分析,气候生产潜力与实际生产潜力均以草甸草原最高,分别为589.68 g C·m^-2·a^-1和349.78 g C·m^-2·a^-1,山地草甸的气候生产潜力最低,为518.72 g C·m^-2·a^-1,而实际生产潜力以典型草原最低,仅为269.52 g C·m^-2<...     

Mass loss and nutrient dynamics during litter decomposition in response to warming and nitrogen addition in a desert steppe

Plant litter decomposition has been studied extensively in the context of both warming and increased atmospheric nitrogen deposition. However, the temporal patterns of mass loss and nutrient release in response to warming and nitrogen addition remain unclear. A 2-year decomposition experiment aimed to examine the effects of warming and nitrogen addition on decomposition rate, and nitrogen and phosphorus dynamics. The effects of warming and nitrogen addition on decomposition of litter of Stipa breviflora, a dominant species in a desert steppe of northern China, were studied. Warming and nitrogen addition significantly enhanced litter mass loss by 10% and 16%, respectively, and moreover promoted nitrogen and phosphorus release from the litter in the first year of decomposition, followed by an immobilization period. The interactive effects of warming and nitrogen addition on mass loss, nitrogen and phosphorus concentrations of litter were also found during the decomposition. This study indicates that warming and nitrogen addition increased litter mass loss through altering litter quality. These findings highlight that interactions between climate change and other global change factors could be highly important in driving decomposition responses.     

冷水江市农业气候资源及主要农业气象灾害分析

利用1981~2010年冷水江气象台站的气象资料,统计分析了冷水江市作物播种期、生长期、收割期的积温、降水、日照时数等农业气象资源变化特征,研究了主要农业气象灾害,为农业气象资源的有效利用和农业生产提供了科学依据。     

达里诺尔自然保护区近30年湿地动态变化及其影响因素分析

以近30a的LandSat影像为数据源,以达里诺尔自然保护区内的达里诺尔湖、岗更湖以及周围面积较大的沼泽湿地为研究对象,利用RS与GIS技术结合野外调查研究,采用人机交互的方法提取研究区内湖泊湿地及沼泽湿地,并对其动态变化进行分析。分别从气候因素与人为因素两个角度分析研究区内湖泊湿地和沼泽湿地变化的原因。结果表明:1)达里诺尔湖泊面积总体呈现减少的趋势,岗更湖面积总体呈现增加的趋势,沼泽湿地面积总体呈现减少趋势,变化不明显。达里诺尔湖与岗更湖的边界变得圆滑,达里诺尔湖东部萎缩较为严重。2)研究区内年平均降水与气温波动明显,年平均降水量呈下降的趋势,年平均气温呈上升趋势。3)降水量与湖泊湿地及沼泽湿地面积变化之间基本呈正相关关系。气温与湖泊湿地及沼泽湿地面积变化之间基本呈负相关关系。4)人为因素中,旅游接待人次、旅游收入、水产品产量与达里诺尔湖泊面积呈负相关,人口数量、年度牲畜存栏与达里诺尔湖泊面积相关性不显著,即旅游业的发展及渔业的养殖与捕捞是造成湖泊湿地面积减少的主要因素,畜牧业和人口数量的增加对湖泊及湿地的影响不大。     

论《弗洛斯河上的磨坊》对《白孔雀》的影响

从《白孔雀》的环境景物描写、作品的人物形象塑造和结构方式几个方面进行比较分析 ,得出结论 :劳伦斯的《白孔雀》受到乔治·艾略特的《弗洛斯河上的磨坊》的影响