Anthropogenically disturbed potentially toxic elements in roadside topsoils of a suburban region of Bishkek,Central Asia

The ecological environment in Central Asia is vulnerable to pressure from human activity due to the physical geography and climatic fragility of this region. A set of indicators suitable for the future assessment of this pressure needs to be proposed. Thirty‐six topsoil samples (0–5 cm) were collected from roadsides in a suburban region of Bishkek, the capital of the Kyrgyz Republic in Central Asia, and a risk assessment of anthropogenically disturbed potentially toxic elements (PTEs) was systematically conducted with classic statistical methods. The results of detrended correspondence analysis and principal component analysis clearly showed that topsoil samples with high contents of PTEs (Pb, Zn and Cu) were strongly affected by traffic within a distance threshold of 200 m and that anthropogenic effects decreased significantly with increasing distance from the highway. The enrichment factor and anthropogenic contribution for Pb were the highest among the three PTEs, with average values of 2.0% and 47.4%, respectively, suggesting enrichment. However, the results of the human health risk assessment also indicated that noncarcinogenic risks did not occur for any of the anthropogenic PTEs. The reported method provides a new systematic pathway to reveal anthropogenic influences on the geochemical composition of soil. The conclusions of this work will be highly valuable as important guidelines for agriculture, and the results of the PTE contents will provide a scientific basis for soil collection in future studies.     

Effects of agriculture,climate, and policy on NDVI change in a semi-arid river basin of the Chinese Loess Plateau

In 1999, the Grain for Green Project was implemented by the Chinese government. Since then, the vegetation of Zuli River Basin, a semi-arid river basin of the Chinese Loess Plateau, has been greatly changed. Clearly understanding the impact of natural and artificial factors on vegetation change is important for policy making and ecosystem management. In this study, spatio-temporal variations in vegetation cover in Chinese Zuli River Basin during 1999–2016 were investigated using Landsat normalized difference vegetation index (NDVI) data. Analyses of several indicators, including changes in NDVI in different slopes and land use changes and the relationships between climatic factors and NDVI change, were presented to quantitatively evaluate the effects of agriculture, climate, and policy on NDVI change. The NDVI in the Zuli River Basin increased during the study period, and the main contributors to this change were forest in 1999–2011, cropland, abandoned farmland, and grassland in 2009–2016, and land with slopes ≤ 15°. Land with slope > 15°, where the “Project” was implemented, slightly contributed to the increase in regional NDVI. In 1999–2011, the project (?98.16%) combined with climate change (?68.18%) showed negative effects on the increase in NDVI in the Zuli River Basin, but agriculture (22.28%) played a positive role in increasing this index. In 2009–2016 and 1999–2016, the project (38.45% and 35.25%, respectively), the project combined with climate change (49.83% and 46.30%, respectively), agriculture (18.61% and 23.30%, respectively), promoted increases in NDVI in the basin.     

Phenotypic plasticity in the morphology of small benthic Icelandic Arctic charr (Salvelinus alpinus)

Intraspecific phenotypic diversity is the raw material for evolution, so understanding its origin and maintenance is critically important for conservation of biodiversity. Intraspecific diversity in a trait or a suite of traits can result from genetic diversity and/or phenotypic plasticity. The two are, however, not independent as plasticity has been shown to evolve. In this study, we evaluated the importance of phenotypic plasticity in generating morphological diversity in populations of small benthic Arctic charr in Iceland, using a rearing experiment with contrasting modes of feeding. We also examined the association between phenotypic plasticity in offspring groups generated by the contrasting feeding modes and important ecological variables characterising the natural habitats of the respective populations. Although the level of plasticity could not be related to any of the ecological measurements, clear differences in morphological reaction norms among populations suggest that plasticity is an important aspect of morphological diversity of the charr. It is not clear whether that plasticity is adaptive, but it is notable that reaction norms in all populations have similar reaction to the treatments.     

三燕时期辽西地区农业发展述论

魏晋南北朝时期中原的战乱促使河北山东等地的世家大族及流民纷纷迁徙到辽西地区，此地的人口数量大为增加，且带来了中原地区的先进生产技术。十六国时期，先后统治辽西地区的前燕、后燕、北燕三个地方政权对农业的重视和发展，加之优越的生态环境和悠久的农耕基础，辽西农业在耕作技术、作物的种类、水利灌溉等方面都有了较快发展，且带动了慕容鲜卑由畜牧经济向农耕经济的转变。农业生产虽受自然灾害和战争等因素的限制但整体上呈现波浪式发展。     

播期对川中丘陵区油菜倒伏性状的影响

油菜机械化生产中,植株倒伏是影响机械化收获的重要因素。为探讨不同播种期对川中丘陵区油菜倒伏性状的影响,以川油36和蓉油18为供试材料,分别设置9月22日、9月29日、10月6日、10月13日和10月20日5个播期处理,分析不同播期条件下油菜生育期气象因子、倒伏性状指标的变化情况。结果表明,随播种期推迟,油菜生育期内的降水量、积温、日均最高气温、日均最低气温和日照时长均逐渐下降,生育期逐渐缩短,成熟期植株株高、分枝部位、根颈粗、茎秆粗降低,倒伏系数增加。油菜抗倒伏能力在9月22-29日播期处理之间最强。因此,川中丘陵区油菜的适宜播期为9月下旬。     

蝴蝶兰成花品质的影响因素研究进展

蝴蝶兰商品化大规模栽培非常成功,在花卉市场所占比重越来越大。为了在国内生产环境下生产出更高品质的蝴蝶兰商品花,本文从品种、温度、光照、水分、气体、肥料等方面对蝴蝶兰成花品质的影响因素进行综述,旨在解决营养生长、昼夜温差等因素对成花品质的影响,以期为蝴蝶兰工厂化生产提供一定的理论支持。     

参考作物蒸散量对气象要素的敏感性分析

为了研究参考作物蒸散量(ET_0)对气象要素的敏感性,利用新乡地区1951―2003年逐日气象资料,由Penman-Manteith公式计算参考作物蒸散量,采用敏感曲线和敏感系数方法分析了参考作物蒸散量对气象要素的敏感性。结果表明,温度、风速和日照时间3种气象要素与ET_0正相关,相对湿度与ET_0负相关。1―12月,相对湿度和风速的敏感系数表现为"先减小后增大"趋势,而日照时间和温度敏感系数表现为"先增大后减小"趋势。在全年中,ET_0对气象要素的敏感程度表现为相对湿度风速日照时间温度;第一、四季度各气象要素在季尺度中的敏感性均为相对湿度风速日照时间温度,第二季度表现为相对湿度日照时间风速温度,第三季度表现为相对湿度日照时间温度风速;冬小麦生育期典型时段内各气象要素敏感性在1、3、10月份均表现为相对湿度风速日照时间温度,5月则表现为相对湿度日照时间风速温度。     

中国粮食主产区主要气象因子时空演变特征及其对参考作物蒸散量影响

准确评估粮食主产区气象因子变化特征及对参考作物蒸散量(reference crop evapotranspiration,ET0)的影响,对农田水文循环、区域农业水资源优化配置与高效利用等具有重要意义。利用中国粮食主产区258个气象站点1961―2013年的逐日气象资料,采用Penman-Monteith公式计算ET0,通过M-K趋势检验法、偏相关分析、多元线性回归计算贡献率等方法,分析了1961—2013年中国粮食主产区主要气象因子时空演变及其对ET0变化的贡献特征。结果表明,1961—2013年中国粮食主产区相对湿度、温度、降水在空间上由南至北呈降低趋势,而日照时间和风速则由南至北呈增高趋势;1961—2013年中国粮食主产区全区、温带湿润半湿润地区(I区)、温带干旱半干旱地区(II区)、亚热带湿润地区(III区)及暖温带半湿润地区(IV区)多年平均气温均呈增大趋势,平均风速、相对湿度、降水与日照时间均呈减小趋势;1961—2013年中国粮食主产区年内ET0均呈锯齿状下降,且ET0在四季呈现出夏季春季秋季冬季的特征;多年平均风速、气温、日照时间与ET0在全区及各分区总体均显著正相关(P0.05),而相对湿度与ET0在全区及各分区均极显著负相关(P0.01);1961—2013年中国粮食主产区全区及I~IV区气温、风速、相对湿度对ET0变化均具有较大贡献,其中相对湿度为I区、III区及IV区的主要气象驱动因子,其次为平均气温和风速;而II区ET0变化的主要驱动因子为风速,其平均贡献率WII(风速)为0.37;综上所述,中国粮食主产区主要气象因子变化特征与ET0的响应,均呈现出区域性、季节性差异。     

Comparing chamber and eddy covariance based net ecosystem CO2 exchange of fen soils

Due to their high emission potential, the reporting of CO₂ emissions from peatlands requires exact emission factors for different land use categories. Recently used emission factors are mainly based on CO₂ flux measurements by chamber techniques or the micrometeorological eddy covariance (EC) method. However, evidence about the reliability and comparability of annual CO₂ balances based on these methods is scarce. Therefore, manual chamber measurements of ecosystem respiration (R_ECO) and net ecosystem exchange (NEE) were conducted for two years (March 2012–April 2014) to model annual balances of two sites on fen soils with different land use intensity in northern Germany: an unutilized and rewetted grassland (UG) and an intensively utilized wet grassland (GW). Simultaneously, EC measurements of NEE were conducted on the sites. Two reasons for occasionally great deviations in NEE between the methods could be observed: (1) the accordance of both methods was most hampered during transition periods such as the beginning of the growing season and the onset of regrowth after a grassland defoliation due to different spatial scales of EC and chamber measurements and (2) R_ECO and gross primary production (GPP) partitioned from EC NEE measurements were systematically lower than those from the chamber‐based model, which could be a result of the EC energy balance gap. Differences were more pronounced for the managed site GW as a result of more frequent regrowth periods. It is concluded that the EC and chamber method can show comparable results for the CO₂ exchange of grasslands on fen soils when the limitations of both methods are known and considered for the reporting of emission factors. These limitations are due to energy balance closure and potentially biased footprints for EC and a restricted representativeness especially during early stages of plant development for the chamber method.     

我国小城镇低碳经济发展的限制因素与解决策略

阐述了低碳经济的产生背景和我国低碳经济发展的必然性,在分析我国小城镇低碳经济发展的限制因素基础上,提出小城镇低碳经济今后发展的解决策略和建议。