Regional nitrogen budgets for China and its major watersheds

Since the Changjiang River, Huanghe River and Zhujiang River are the three major rivers in China that are flowing into the Pacific Ocean, this paper addresses nitrogen budgeting, source (input) and sink (output and storage), in these three river valleys, and the China watershed as well. In the China watershed, the anthropogenic reactive N has far exceeded the terrestrial bio-fixed N in nature, and human activities have significantly altered the N cycling in this region. In 1995, the total amount of anthropogenic reactive N in China reached 31.2 Tg with 22.2 Tg coming from synthetic fertilizers and 4.18 Tg from NO_x emission from fossil fuel combustion, and the input of recycling N amounted to 30.5 Tg, consisting mainly of human and animal excrement N, reflecting the intensity of the human activity. The sink of N includes N in the harvested crop, denitrification and storage in agricultural soils, transportation into waterbodies and volatilization of NH₃. N output and storage in soil reached up to 48–53 Tg. Of this amount, 14 Tg was in the harvested crops, 12 Tg stored in agricultural soils, 11 Tg transported into waterbodies, 5 – 10 Tg denitrified in the soils and a limited amount exported through food/feed.In this paper – besides the N budget in the China watershed – the N budgets and especially N transports into waterbodies in the Changjiang, Huanghe and Zhujiang river valleys are estimated.     

Nitrate elimination by denitrification in hardwood forest soils of the Upper Rhine floodplain – correlation with redox potential and organic matter

Denitrification in floodplains is a major issue for river- and groundwater quality. In the Upper Rhine valley, floodplain forests are about to be restored to serve as flood retention areas (polders). Besides flood attenuation in downstream areas, improvement of water quality became recently a major goal for polder construction. Redox potential monitoring was suggested as a means to support assessment of nitrogen elimination in future floodplains by denitrification during controlled flooding. To elucidate the relationship between redox potential and denitrification, experiments with floodplain soils and in situ measurements were done. Floodplain soil of two depth profiles from a hardwood forest of the Upper Rhine valley was incubated anaerobically with continuous nitrate supply. Reduction of nitrate was followed and compared with redox potential and organic matter content. The redox potential under denitrifying conditions ranged from 10 to 300 mV. Redox potential values decreased with increasing nitrate reduction rates and increasing organic matter content. Furthermore, a narrow correlation between organic matter and nitrate reduction was observed. Experiments were intended to help interpreting redox potentials generated under in situ conditions as exemplified by in situ observations for the year 1999. Results obtained by experiments and in situ observations showed that monitoring of redox potential could support management of the flooding regime to optimize nitrogen retention by denitrification in future flood retention areas.     

澜沧江流域北部中华蜜蜂食源和营养生态位随海拔梯度的变化特征

为了解澜沧江流域北部中华蜜蜂(Apis cerana cerana)的分布,探究中华蜜蜂的食源和营养生态位沿海拔梯度的变化特征,调查了澜沧江流域北部各海拔区域中华蜜蜂的种群分布,运用蜂蜜孢粉学(melissopalynology)分析了各海拔区域中华蜜蜂蜂蜜中花粉的组成特征和变化规律,并综合分析了海拔、中华蜜蜂营养生态位和蜂蜜中花粉的相关性,探讨了自然环境与中华蜜蜂的分布,海拔梯度与蜜粉源植物、中华蜜蜂的食源和营养生态位的关系。结果表明:澜沧江流域北部中华蜜蜂的食源种类丰富,中华蜜蜂种群主要分布于2200—2800 m海拔区域。不同海拔区域中华蜜蜂采食花粉的种类和数量不同,中华蜜蜂种群分布多的海拔区域,蜂蜜中花粉的种类较多,但花粉数量相对少。随着海拔梯度升高,中华蜜蜂蜂蜜中花粉的数量表现为先降后增,而花粉的种类则表现为先增后降。不同海拔区域的中华蜜蜂营养生态位存在差异,推测各海拔区域蜜粉源植物分布、中华蜜蜂种内和种间授粉昆虫及食草动物等竞争因素不同,但各海拔梯度间的变化差异不显著。海拔与中华蜜蜂营养生态位呈正相关(r=0.051),相关性不显著;海拔与蜂蜜中花粉数量呈正相关(r=0.047),与蜂蜜中花粉种类呈正相关(r=0.144),相关性都不显著;中华蜜蜂营养生态位与蜂蜜中花粉的种类呈负相关(r=-0.305),相关性显著(P!0.05);与花粉的数量呈负相关(r=-0.064),相关性不显著。蜂蜜中花粉的数量与种类呈正相关(r=-0.303),且相关性显著(P!0.05)。     

岷江上游不同景观结构小流域水量平衡的比较

研究了1988～2002年岷江上游两个小流域（镇江关流域和黑水河流域）不同景观结构（土地覆盖、海拔、坡度、斑块密度、最大斑块指数等）对水量平衡的影响.基于两个流域土地覆盖类型、1988～2002年多年平均降水量和蒸散量的空间分布、两个流域土地覆盖类型同期多年平均径流深度的数据,得到不同土地覆盖类型的海拔、坡度、坡向与降雨、蒸散、径流的关系.结果表明,两个流域有林地海拔、坡度、坡向的不同导致其降水、蒸散降水比、径流降水比各异;两个流域草地水量平衡对景观格局的响应模式与有林地基本一致;由于黑水河流域的耕地分布在干旱河谷中,其蒸散量远远大于降水量,耕地本身的景观结构（坡向、坡度,斑块密度）并不对其水量平衡产生影响,这一点与镇江关完全不同.     

Intracellular distribution of cardiac glycosides in leaves of Convallaria majalis

In order to investigate the intracellular distribution of the cardiac glycosides in leaves of Convallaria majalis, cell organelles were prepared by several methods. After mechanical disruption of the cells and differential centrifugation, the cardenolide content obtained was determined using the Baljet reaction. Most of the cardiac glycoside fraction was found in the soluble supernatant. However, a low but significant amount was also found in the 10 000g particles. Protoplasts and vacuoles were prepared by enzymic digestion of leaves. The cardenolide to protein ratio of vacuoles was far higher than that of protoplasts or the cytoplasmic fraction. The cardenolide content of isolated vacuoles relative to their number agreed well with the corresponding value obtained for protoplasts. This demonstrates clearly that cardiac glycosides are stored predominantly in the vacuoles of Convallaria majalis.     

孢粉记录的重庆岩溶槽谷区700年来植被演替与喀斯特石漠化

在精确AMS¹⁴C测年的基础上,对采自重庆中梁山岩溶洼地的剖面样品进行了孢粉分析,并结合详细的历史文献资料,获取了该地区近700年以来的植被变迁与石漠化演化记录。结果显示：（1）1274-1553 cal a AD研究区周围主要分布以松属、柏科/杉科占优势的亚热带常绿针叶林,伴人植物花粉少量出现,人类活动相对较弱。（2）1553-1780 cal a AD,针叶树松属、柏科/杉科花粉含量下降,伴人植物花粉增多,指示研究区人类活动开始加强。（3）1780-1840 cal a AD,松属花粉含量急剧下降,灌木和伴人植物花粉急剧增加,指示该地区人类活动加剧,石漠化现象出现。（4）1840-2000 cal a AD,玉米花粉含量大幅度增加,表明人类活动更加强烈,石漠化现象进一步加剧。近700年来不断增加的人类活动是重庆地区植被退化、石漠化现象严重的重要因素。该研究结果对重庆岩溶地区的全面治理,恢复和重建自然生态环境具有重要的指示意义。     

Synthesis and Olfactory Characterization of Silicon‐Containing Derivatives of the Acyclic Lily‐of‐the‐Valley Odorant 5,7,7‐Trimethyl‐4‐methylideneoctanal

5‐Methyl‐4‐methylidene‐6‐(trimethylsilyl)hexanal ( 1b ), a sila analog of the acyclic lily‐of‐the‐valley odorant 5,7,7‐trimethyl‐4‐methylideneoctanal ( 1a ), and the Si‐containing derivatives 2 – 6 were prepared in multistep syntheses, starting from Cl₃SiH and Cl₂SiMe₂, respectively. Compounds 1b, 2 – 6 , and their new precursors were characterized by elemental analyses (C, H, N) and NMR spectroscopic studies (¹H, ¹³C, ¹⁵N, and ²⁹Si). To gain more information about the structure? odor correlation in the family of lily‐of‐the‐valley or ‘muguet’ odorants, C/Si analogs 1a / 1b and derivatives 2 – 6 were evaluated for their olfactory properties.     

The resurgence in resource nationalism and private protected areas: Through the lens of Save Valley Conservancy's indigenisation

It has been observed that the resurgence in resource nationalism in the past decade worldwide has profound implications for all economic sectors including protected areas. However, a review of the international protected area literature reveals a paucity of studies that make use of the construct of resource nationalism as an analytical framework. This paper addresses this gap by bringing to the fore how Zimbabwe's ZANU PF (the political party that brought the country's independence in 1980) has deployed and extended this construct from the 2000 land reform programme to one of the world's largest private wildlife sanctuaries, namely the Save Valley Conservancy (SVC). In doing so, the paper relies extensively on the narratives, debates and legitimations of the ruling elite and other stakeholders around the recent ‘indigenisation’ of the SVC. It was found that a range of actors attempted to use resource nationalism as a ‘resource’ to further their own private economic and political interests whilst others resorted to the conservation discourse. One of the main conclusions of this paper is that managers of protected areas need to be sensitive to the resurgence in resource nationalism. In this connection, it is argued that the ability to negotiate the resurgence in resource nationalism will determine the fate of some private protected areas. The study suggests possible solutions around the indigenisation of SVC and points to future research priorities.     

岷江干旱河谷造林对土壤微生物群落结构的影响

为了探讨不同造林时间和立地条件对土壤微生物群落结构的影响,采用磷脂脂肪酸(PLFAs)法测定了岷江干旱河谷地区不同造林时间(2002、2006和2011年)及不同立地条件(退耕地和宜林荒山地)营建的岷江柏人工林土壤微生物生物量及群落结构的变化情况。结果表明:由于造林时间较短,不同造林时间的人工林间土壤化学性质没有差异,但土壤微生物生物量和各菌群生物量差异显著,且随着造林时间的增加而增加。不同立地条件下则表现为退耕还林地土壤微生物生物量和各菌群生物量较高。说明土壤微生物对外界因素变化的反映更灵敏。相关性分析结果显示土壤全氮含量与土壤微生物生物量及各菌群生物量显著相关,是影响土壤微生物群落结构的关键因素。     

1980—2011年川东平行岭谷区农田土壤有机碳动态

选取重庆市垫江县为川东平行岭谷的典型区,使用1980第二次土壤普查和2011年实测土壤数据,基于土壤类型,运用通用SOC密度/储量计算法和逐步回归分析,对研究区1980—2011年0—20 cm农田SOC动态和动因进行分析,结果表明:(1)1980—2011年农田0—20 cm土层SOC密度/储量总体表现为略有增加态势,单位面积碳增量2307.63 kg C/hm2,碳增汇235945.83 t,增幅为10.74%,年均增长速率为72.11 kg C hm-2a-1;(2)丢碳、固碳和相对平衡面积比37.61∶49.03∶13.36,总体呈西部、西北部高于南部、东南部,更高于东北部和西南部的格局;(3)宏观上1980—2011年农田0—20 cm土层SOC密度/储量变化与土壤类型的分布及利用有很大关系,尤其是黄壤和紫色土在相异的质地本底和不同的扰动下,展现出相反的碳汇/源状态;(4)微观上SOC密度年均变化速率影响最大的因素是SOC密度初始值全N密度C/N比,且全N密度和C/N比拥有正向影响,SOC密度初始值则相反;⑸结果为川东平行岭谷区借助施加适当投入和合适的耕作与管理实践,有效管理农田表层SOC库提供科学依据。