不同植被恢复模式对土壤有机碳分子结构及其稳定性的影响

为揭示不同植被恢复模式对土壤有机碳分子结构及其稳定性的影响机理,分别在浙江凤阳山国家级自然保护区的石梁岙和凤阳湖设置样地,采用13C核磁共振技术分析常绿阔叶林与杉木林、柳杉林与针阔混交林全土和不同粒级(0~0.5、>0.5~2.0、>2.0~5.0、>5.0 mm)土壤团聚体中有机碳的质量分数及其分子结构特征. 结果表明:①常绿阔叶林0~20 cm层全土w(有机碳)(12.84 g/kg)显著高于杉木林(9.98 g/kg),柳杉林(13.93 g/kg)显著高于针阔混交林(11.54 g/kg) (P<0.05). 不同植被恢复模式下,土壤团聚体w(有机碳)总体上均随着粒径的增大呈降低趋势. ②与杉木林相比,常绿阔叶林全土有机碳中w(烷氧碳)较高,w(烷基碳)、w(芳香碳)、w(烷基碳)/w(烷氧碳)、w(疏水碳)/w(亲水碳)则较低,显示常绿阔叶林全土有机碳稳定性较差;与针阔混交林相比,柳杉林全土有机碳中w(烷基碳)、w(烷基碳)/w(烷氧碳)、w(疏水碳)/w(亲水碳)较高,w(烷氧碳)则较低,显示柳杉林全土有机碳稳定性较好. 与0~20 cm层相比,不同植被恢复模式下>20~40 cm层全土w(烷氧碳)均明显降低,w(烷基碳)、w(烷基碳)/w(烷氧碳)、w(疏水碳)/w(亲水碳)均明显升高,有机碳稳定性变好. ③随着粒径的增大,不同植被恢复模式下土壤团聚体的w(烷基碳)、w(烷基碳)/w(烷氧碳)、w(疏水碳)/w(亲水碳)均呈降低趋势,w(烷氧碳)均呈升高趋势,说明团聚体结合的有机碳稳定性逐渐变差. 研究显示,不同植被恢复模式下的不同树种组成是影响土壤有机碳质量分数及其分子结构、稳定性差异的主要因素.      

Tears,fears and cheers: responses to the post‐disaster school relocation policy in China

This paper reports on the results of a qualitative study on the responses of Chinese school children in one junior middle school and their parents to China's post‐disaster school relocation policy. The sample comprised 22 pairs of parent–child dyads and two pupils whose parents could not be contacted. The study results were reported using Chambers and Wedel's (2009) conceptual framework, which delineates the fundamental elements of a policy. Content analysis was used to generate themes related to policy elements, such as goals, benefits and services. Both repetitive themes and idiosyncratic perspectives were reported so as to present a diversity of views. Despite adjustment difficulties and administrative problems reported by the study participants, the policy attention given to the rapid restoration of formal schooling for children was generally appreciated. The move back to the new school was greeted with cheer.     

蠡湖水环境综合整治工程实施前后水质及水生态差异

为探讨水环境综合治理工程措施对蠡湖水生态环境的改善效果,对工程实施前后蠡湖水生态环境的变化及趋势进行了分析. 结果表明,水环境综合治理工程实施后,蠡湖水质明显好转,水体中ρ(TN)、ρ(TP)、ρ(COD_Mn)和ρ(Chla)年均值显著下降(P<0.01),ρ(TN)、ρ(TP)、ρ(Chla)分别由综合治理前 (1992—2002年平均值) 的5.77、0.19 mg/L和59.90 μg/L降至综合治理后的3.13、0.13 mg/L和27.12 μg/L,ρ(COD_Mn)则由7.09 mg/L降至5.00 mg/L以下;表层沉积物中w(OM)、w(TN)和w(TP)分别由2001年的40.40、1.19、2.61 g/kg降至2012年的19.60、1.16、0.59 g/kg;2012年生态修复工程区内初步形成了一个水生植物较为完整的生态系统. 综合整治后,水质改善效果明显,但部分水体感观指标〔如ρ(TSS)、SD(透明度)〕改善效果不明显,底栖动物优势种群仍为耐污种,生态系统完全恢复还需时日. 因此,有必要进一步开展以提高透明度、恢复沉水植物为核心的生态优化调控,促进蠡湖由藻型浊水稳态向草型清水稳态转变.      

华南退化生态系统三种典型生态恢复模式的小气候效应研究

为了评价南亚热带典型退化生态系统典型生态恢复模式的小气候调节效应,从而为退化生态系统生态恢复方式和造林树种的选择提供参照,作者在广东鹤山森林生态系统国家野外科学观测研究站的3种典型生态恢复模式样地,自然恢复草坡、马尾松林（Pinus massoniana）、马占相思林（Acacia mangium）中安装了HOBO小气候仪,对光辐射、风速风向、降水、土壤含水量、地温、气温等小气候指标进行为期1年的自动观测,并进行了对比分析,结果表明,（1）华南退化生态系统3种典型生态恢复模式具有不同的小气候效应,在林间温度调节方面,人工林和草坡的平均林间温度相差不大,但草坡的最低、最高温度均比人工林低和高。人工林的林间温度变化较草坡小,具有更好的保温调节作用。对比2种人工林,不管是平均温度还是最高温度马占相思林都略大于针叶林,而二者最低温度相差不明显。针叶林的保温调节作用略优于阔叶的马占相思林;（2）在土壤温度方面,地表温度全年基本都表现为草坡〉马占相思林〉针叶林,草坡的地表温度的波动远大于2种人工林;全年20 cm土壤温度3─12月都表现为草坡〉马占相思林〉针叶林,1─2月相反,草坡20 cm土层的土壤温度波动相对较大,人工林的波动很小。（3）3种恢复模式中,自然恢复草坡的辐射强度明显高于2种人工林,年辐射总量分别马占相思林和针叶林的1.9和5.8倍,马占相思林的年辐射量为针叶林的3倍。人工林,特别是乡土的针叶林能给林下生物构建更为稳定、适中的辐射环境。（4）人工林的平均林间风速、最大阵风风速均少于草坡,针叶林的风速小于阔叶林,针叶林降低风速的效果好于相思林和草坡。（5）人工林的林间相对湿度均高于草坡,针叶林的林间空气湿度略大于相思林,针叶林的保湿效果更好。在退化生态系统恢复过程中?     

佛山水道及其支涌复氧试验研究

对几种曝气方式的溶解氧提升情况、充氧动力效率,及COD、氨氮的去除率进行了简单比较,得出微孔雾化曝气和橡胶坝曝气是适合佛山水道及其支涌河流人工复氧的最佳方法.     

持续放牧和围封对科尔沁退化沙地草地碳截存的影响

研究了科尔沁退化沙地草地持续放牧和围封恢复下土壤-植物系统的碳(C)贮存,以揭示草地管理对C动态的影响.结果表明,0～15cm土壤OC和植物系统贮存的C(包括初级生产固定的C,立枯和地表凋落物C和根系C)贮量大小为:围封10年草地(584g·m^-2和309 g·m^-2)＞围封5年草地(524g·m^-2和146g·m^-2)＞持续放牧草地(493g·m^-2和95 g·m^-2).在围封10年,围封5年和持续放牧草地中,0～15cm土壤贮存C分别占各自土壤-植物系统C的65.3%,78.2%和83.9%.在风蚀严重的科尔沁沙地,持续放牧对植被,土壤及其周围环境有极严重的恶化作用.采取围封恢复措施后,植被恢复和凋落物积累使土壤免遭风蚀,也显著增加了土壤有机质的输入,因而显著作用于大气C的截存.但排除家畜放牧的长期围封使植物C向土壤C的再循环受到限制,截存的大部分C以凋落物的形式积存在土壤表面,需进一步深入研究围封的时间尺度.研究结果表明,退化沙地草地在采取有效的保护措施后,可以由C源变为C汇.     

The Brown Trout Population at Loch Fleet Eight Years After Liming

Abstract

At the start of the Loch Fleet Project in 1984, the Loch and the upper 7 km of its efferent stream were found to be devoid of trout (Salmo trutta) as a result of acidification. Following the liming treatments applied to the catchment, from 1986 the formerly toxic water quality conditions (pH ～ 4.5, calcium ～ 1 mgl^?1, elevated aluminium and heavy metal levels) were eliminated, and trout were reintroduced on two occasions, in 1987 and 1988. A total of 520 fish were stocked, at a combined density equivalent to 5.5 kg ha^?1. Surveys of the loch and stream populations were carried out annually until 1993 to monitor their development, using a range of techniques, including electrofishing, gill-netting, seine-netting, spawner trapping and mark-release recapture methods. Length and scale- analysis were used to investigate fish growth.

The trout population in Loch Fleet expanded rapidly as a result of natural spawning in the loch's main feeder stream, augmented by the use of an artificial spawning bed which was constructed at the loch outlet in 1990. in mid-1983 the stock density, estimated by mark-recapture census methods, had increased to 24.9 kg ha^?1. Poor recruitment in the years 1991–93, however, reduced the rate of expansion and resulted in a population comprising mainly older individuals. the poor recruitment in these years was not fully explained but was not caused by water quality and was most likely a result of fry washout by spring spates.

Fish growth rates were high initially and were estimated on the basis of the Elliott trout growth model to be optimal for the prevailing water temperature regime of the loch. By 1991, growth rates had fallen, probably as a result of competition for food, but showed signs of recovery towards the end of the study period in 1993, following the period of lower population densities of young fish.

Trout rapidly repopulated the loch's outlet stream after 1987 but have remained sparse and have shown no signs of spawning within most of the stream. Water analyses have shown that the liming of the Loch Fleet catchment has minimal impact on downstream waters when flows are high, so that potentially toxic acid episodes have not been prevented.     

治理修复型水生态补偿问题分析

流域生态补偿已成为水文水资源领域的一个热门研究课题,也是解决水资源开发利用过程中区域用水矛盾、生态破坏的一种有效途径。从流域生态破坏的不同层面和根源出发,结合流域整体协调发展的管理策略和行动计划,给出流域治理修复型水生态补偿的实施目标。从双方自由博弈纳什均衡的层面出发,进行实施流域水生态补偿的经济最优条件分析;结合生态补偿产生的经济学原理,给出影响流域水生态补偿实施的相关性分析。针对流域生态治理中遇到的实际问题,阐述影响流域治理修复型水生态补偿的实施细节。     

Applicability of Montreal Process Criterion 4 — soil and water conservation — to rangeland sustainability

SUMMARY

Criterion 4 of the Montreal Process addresses the conservation of soil and water resources as a way to assess the sustainability of a nation's forests. For the most part, the indicators under this criterion are relevant to rangelands. The area and percent of rangeland with significant soil erosion apply equally well to both biomes. Percent of streams with flow rates and timing outside its range of historical variation is also equally important, although a measure of proper functioning and condition may provide a better measure of the indicator. The area and percent of rangeland with diminished soil productive capability because of a loss of reduced organic matter or changed physical characteristics can be useful indicators locally and regionally.     

地下水六价铬运移的仿真及场地修复限值探讨

根据渗流理论,考虑地下水中水头变化的影响,利用COMSOL软件,对六价铬在地下水中的运移进行数值模拟,得到地下水压力水头和六价铬在地下水中的迁移变化规律,为六价铬对地下水的污染研究和预测提供重要的分析数据。并借此计算得出场地地下水的修复指导限值为3.17 mg/kg。