淇澳岛红树林生态系统中重金属含量相关性

采集珠海淇澳岛北部大围湾的红树林区潮间带沉积物和植物组织样品若干,测定各样品中Cu、Zn、Cd和Pb的含量,四种重金属含量在各沉积物中、各植物组织中以及沉积物和植物组织之间的相关性。研究表明,沉积物中Pb和Zn含量呈极强正相关,Pb、Zn与Cd含量之间呈强正相关,其他各类重金属之间的相关性不显著。四种重金属与沉积物颗粒形态相关性均不显著。红树植物各组织对四种重金属的富集系数范围为0.001~0.72,0.006~0.39,0.053~1.97和0.004~0.24,富集能力与林龄正相关,其中对Zn、Cd和Pb的富集系数与土壤中含量呈负相关,表明在过高重金属污染胁迫的环境中红树植物有自行降低富集能力以避免被伤害的趋势。     

莱州湾滨海平原咸水入侵分析与趋势预测——以山东省广饶县为例

文章以鲁北平原山东省广饶县为例,阐述了咸、淡水形成的地质背景、咸淡水变化带形成与演化;分析了大规模开发利用地下水引起的咸水入侵的历史与现状;采用非确定性模型方法对咸水入侵趋势进行了预测,提出了缓解咸水入侵的对策与建议。取得的主要认识和结论为:(1)鲁北平原自山前冲洪积扇向莱州湾滨海平原,地下水水质具有水平和垂直分带特征;(2)20世纪70年代中期大量开采南部地下淡水后,地下淡水水位持续下降,破坏了咸淡水之间的水动力平衡,北部咸水向南入侵,引起淡水咸水、机井报废等一系列环境地质问题;(3)预测结果表明,在不采取调控措施情况下,咸淡水界面以每年平均240m速度向南部推进;(4)人工回灌、营造淡水帷幕并减少淡水区开采量是防止咸水入侵的有效途径。     

Soil hydraulic response to land-use change associated with the recent soybean expansion at the Amazon agricultural frontier

Clearing for large-scale soy production and the displacement of cattle-breeding by soybeans are major features of land-use change in the lowland Amazon that can alter hydrologic properties of soils and the runoff generation over large areas. We measured infiltrability and saturated hydraulic conductivity (Ksat) under natural forest, pasture, and soybeans on Oxisols in a region of rapid soybean expansion in Mato Grosso, Brazil. The forest-pasture conversion reduced infiltrability from 1258 to 100 mm/h and Ksat at all depths. The pasture-soy conversion increased infiltrability from 100 to 469 mm/h (attributed to shallow disking), did not affect Ksat at 12.5 cm, but decreased Ksat at 30 cm from 122 to 80 mm/h, suggesting that soybean cultivation enhances subsoil compaction. Permeability decreased markedly with depth under forest, did not change under pasture, and averaged out at one fourth the forest value under soybeans with a similar pattern of anisotropy. Comparisons of permeability with rainfall intensities indicated that land-use change did not alter the predominantly vertical water movement within the soil. We conclude that this landscape is well buffered against land-use changes regarding near-surface hydrology, even though short-lived ponding and perched water tables may occur locally during high-intensity rainfall on pastures and under soybeans.     

Forest soil CO2 fluxes as a function of understory removal and N-fixing species addition

We report on the effects of forest management practices of understory removal and N-fixing species (Cassia alata) addition on soil CO2 fluxes in an Eucalyptus urophylla plantation (EUp), Acacia crassicarpa plantation (ACp), 10-species-mixed plantation (Tp), and 30-species-mixed plantation (THp) using the static chamber method in southern China. Four forest management treatments, including (1) understory removal (UR); (2) C. alata addition (CA); (3) understory removal and replacement with C. alata (UR+CA); and (4) control without any disturbances (CK), were applied in the above four forest plantations with three replications for each treatment. The results showed that soil CO2 fluxes rates remained at a high level during the rainy season (from April to September), followed by a rapid decrease after October reaching a minimum in February. Soil CO2 fluxes were significantly higher (P < 0.01) in EUp (132.6 mg/(m2·hr)) and ACp (139.8 mg/(m2·hr)) than in Tp (94.0 mg/(m2·hr)) and THp (102.9 mg/(m2·hr)). Soil CO2 fluxes in UR and CA were significantly higher (P < 0.01) among the four treatments, with values of 105.7, 120.4, 133.6 and 112.2 mg/(m2·hr) for UR+CA, UR, CA and CK, respectively. Soil CO2 fluxes were positively correlated with soil temperature (P < 0.01), soil moisture (P < 0.01), NO3?-N (P < 0.05), and litterfall (P < 0.01), indicating that all these factors might be important controlling variables for soil CO2 fluxes. This study sheds some light on our understanding of soil CO2 flux dynamics in forest plantations under various management practices.     

基于CVM的宁波天童天然林碳汇贸易研究

以宁波天童天然林为例,探讨了将天然林碳汇纳入碳汇贸易的方法和途径,采用条件价值评估法(CVM)估算了天童天然林碳汇价值,并探讨了天然林碳汇贸易的可行性.结果表明:(1)与人工林碳汇相比,天然林碳汇在数量、生态功能和保育价值方面具优势,将天然林碳汇纳入碳汇贸易,是对现有人工林碳汇贸易的有益补充;(2)公众对碳汇贸易普遍持...     

环渤海地区海冰水资源农业利用研究

环渤海地区盐碱滩涂地面积广阔,淡水资源紧缺现状制约着该地区土地资源开发和农业利用。新型海冰水资源的开发和利用有望打开这种尴尬局面。实验结果表明:海冰水灌溉下台田土壤耕作层平均盐分含量为2.45 g/kg,可以保障土壤耕层安全;3 g/L海冰水灌溉与无灌溉处理相比,油葵增产31.3%、甜高粱总糖量增产21.2%、紫花苜蓿增产27.0%。可见以海冰水为水源的"台田-浅池"综合利用模式对环渤海地区改良和利用盐碱地具有重要的参考价值。     

浅析我国森林生态效益补偿制度

概述了中国森林生态效益补偿研究的发展历程和总体状况,通过对森林生态效益补偿制度的回顾、补偿现状的描述,综述相关文献分析了森林生态效益补偿制度存在的一些问题,并提出了相应的建议。     

杨树人工林碳循环对淹水的响应

本文采用涡度相关方法对安徽怀宁杨树人工林的碳通量进行监测,得到微气象数据和通量数据。通过坐标旋转、密度校正和数据插补处理提高数据质量。选取2005年9月淹水期间的数据。分六个阶段进行分析。得到以下结果：（1）在半小时尺度上,在淹水期表观量子效率α随着土壤含水量SWC上升而降低;在未淹水期最大。为-0．0023μmolphoton^-1;退水期最低,为-0．00122mgCO2μmolphoton^-1,退水后恢复到-0,00168mgCO2μmolphoton^-1;α在淹水中2期降低速率最大,在整个淹水期间α的恢复速率是大于降低速率的。（2）生态系统总初级生产力（GEP）在淹水后不断降低．耒淹水期为8．0gCm^-2day^-1．退水后为4．7gCm^-2day^-1,在淹水中2期降幅是最大的达到了16％。（3）生态系统呼吸（Reco）在完全被水淹的第一天降到最低,仅为2．2gCm^-2day^-1;由于温度的影响其变化规律比较复杂。在淹水中2期的变化幅度是最大的;退水后Reco为4．2gCm^-2day^-1恢复到来淹水前的87％。（4）淹水期净生态系统CO2交换量（NEE）的变化表现为先上升后下降的趋势,在淹水中1期最大为-4．2gCm^-2day^-1。退水后最低。为0．6gCm^-2day^-1是未淹水前的17％。     

浅析海岸带侵蚀

在收集各国海岸带侵蚀现象资料的基础上,主要分析了造成海岸带侵蚀的人类活动,列举由海岸带侵蚀现象带来的一系列环境问题,并针对中国海岸带的环境现状提出了相关防护措施。     

海岸带生态环境基础质量遥感评价研究——以上海南汇东滩为例

基于遥感信息获取技术,以上海南汇东滩为例,建立了海岸带生态环境基础质量遥感评价指标体系,对城市生态环境遥感评价模型增加海洋专家打分权重进行改进,并开发海岸带生态环境评价的信息管理工具,实现了研究区生态环境遥感多个年份的定量评价,分析研究区生态环境质量变化原因,为构建更好的海岸带管理决策支持系统,从而更好地管理海岸带资源...