Relationship between stand characteristics and soil properties of two typical forest plantations in the mountainous area of Western Sichuan,China

There is uncertainty and limited knowledge regarding stand characteristics and soil properties of middle-aged pure forest plantations in the mountainous area of Western Sichuan. Plantation forests are almost exclusively planted as monocultures in the Pengzhou forest farm in the western mountainous area of Sichuan Province. This study aimed to assess the spatial and ecological characteristics of middle-aged Cunninghamia lanceolata(Lamb.) Hook. and Cryptomeria fortunei Hooibr. in the Pengzhou forest farm. The relationships and differences between stand growth characteristics and forest soil composition were assessed on the two forests planted simultaneously within the same area and exposed to the same environmental conditions. Cr. fortunei grew sparse, and slower than Cun. lanceolata. Principal component analysis indicated that the soil properties in the Cr. fortunei plantation were better than those in the Cun. lanceolata plantation. Redundancy analysis revealed that the differences in stand structure were affected significantly by the total nitrogen content and pH value. Thus, we propose that Cr. fortunei is planted for priority consideration in the subtropical high mountain area. Further, tending operations and application of fertilizers need to be conducted in Cun. lanceolata forests. Based on theoretical and experimental data, the present study explains why local farmers are more willing to plant Cr. fortunei, and thus provides a useful theoretical reference for the development of sustainable plantations in the future.     

Growth inhibition and oxidative stress in two species of marine diatoms exposed to 1-phenylethanol

1-phenylethanol(1-PEA)is a flavor extensively used in the production of co smetics,beverages,and food.The release of 1-PEA into coastal environments has aroused great concern.However,its potential effects on marine organisms are still unknown.In order to provide a better understanding of the ecological risks of 1-PEA in marine environments,this study determined the toxic effects of 1-PEA on two marine diatoms(Phaeodactylum tricornutum and Skeletonema costatum).The diatoms were grown in culture medium containing different concentrations of 1-PEA for 96 h.The contents of chlorophyll a,chlorophyll c,glutathione(GSH),malondialdehyde(MDA),and the activities of superoxide dismutase(SOD),catalase(CAT)and glutathione peroxidase(GPx),were measured at the end of the exposure period.1-PEA was shown to significantly inhibit the growth of diatoms,with 96-h EC_(50) values of 257.14 mg/L and 126.46 mg/L in P.tricornutum and S.costatum,respectively.In P.tricornutum,the levels of SOD,CAT,GPx,GSH,and MDA were stimulated only when 1-PEA concentrations were close to or greater than the 96-h EC_(50)value.However,in S.costatum,the activities of SOD and CAT,and the syntheses of two chlorophylls were inhibited even at an exposure concentration below the 96-h EC_(50) value.Taken together,these findings indicate a potential ecological risk by discharging 1-PEA into coastal areas and its species-specific toxic effects on marine organisms.     

Fish Assemblage Responses to a Low-head Dam Removal in the Lancang River

Dam removal is becoming an effective approach for aquatic biodiversity restoration in damming river in order to balance the aquatic ecosystem conservation with large-scale cascade damming. However, the effects of dam removal on fish communities in Asian mountainous rivers, which are dominated by Cypriniformes fishes, are still not well known. To determine whether dam removal on a mountainous river benefit restoration of fish diversity, we investigated the response of fish assemblage to dam removal using a before-after-control-impact design in two tributaries of the Lancang River(dam removal river: the Jidu River, and control river: the Fengdian River). Fish surveys were conducted one year prior to dam removal(2012) and three years(2013–2015) following dam removal. We observed rapidly and notably spatio-temporal changes in fish biodiversity metrics and assemblage structure, occurring in the Jidu River within the first year after dam removal. Overall, fish species richness, density and Shannon-Wiener diversity all increased immediately in above-and below-dam sites, and maintained a stable level in subsequent years, compared to unchanged situation in the control river. All sites in the Jidu River experienced shifts in fish composition after dam removal, with the greatest temporal changes occurred in sites below-and above-the former dam, resulting in a temporal homogenization tendency in the dam removed river. These findings suggest that dam removal can benefit the recovery of habitat conditions and fish community in Asian mountainous rivers, but the results should be further evaluated when apply to other dammed rivers since the dam age, fluvial geomorphology and situation of source populations could all affect the responses of fish assemblages.     

Examining the sensitivity of spatial scale in cellular automata Markov chain simulation of land use change

Understanding the spatial scale sensitivity of cellular automata is crucial for improving the accuracy of land use change simulation. We propose a framework based on a response surface method to comprehensively explore spatial scale sensitivity of the cellular automata Markov chain (CA-Markov) model, and present a hybrid evaluation model for expressing simulation accuracy that merges the strengths of the Kappa coefficient and of Contagion index. Three Landsat-Thematic Mapper remote sensing images of Wuhan in 1987, 1996, and 2005 were used to extract land use information. The results demonstrate that the spatial scale sensitivity of the CA-Markov model resulting from individual components and their combinations are both worthy of attention. The utility of our proposed hybrid evaluation model and response surface method to investigate the sensitivity has proven to be more accurate than the single Kappa coefficient method and more efficient than traditional methods. The findings also show that the CA-Markov model is more sensitive to neighborhood size than to cell size or neighborhood type considering individual component effects. Particularly, the bilateral and trilateral interactions between neighborhood and cell size result in a more remarkable scale effect than that of a single cell size.     

海洋有害藻华研究进展

浮游植物不仅是食物链的基础环节,也在生物地球化学循环中起着重要作用。然而,某些种类在一定条件下会过度增殖富集形成有害藻华(因造成水色变为红、绿、褐、金等颜色,所以俗称为赤潮、绿潮、褐潮、金潮等),结果严重影响当地经济、海洋生态系统、全球生物地球化学循环甚至人类健康。近年来,随着水体富营养化、全球气候变化等现象加剧,有害藻华(Harmful Algal Bloom,HAB)的暴发规模和频次呈逐年增加趋势,且相关研究已成为环境生态学领域的热点。本文主要以典型海洋HAB生物为线索,从物种分布、生物监测、主要影响因素、分子机制及防治等方面概述了近十年HAB的主要研究进展,总结了现有研究的优点和不足,并对未来HAB研究做了相关展望。近十年的研究进展主要体现在:(1)不断有新的HAB物种被发现或鉴定,HAB藻类系统分类也不断被更新;(2)鉴定、检测方法包括DNA分析、生物传感器研发应用等有较大改进;(3)藻类毒素生物合成通路的研究有一定进展;(4)在HAB生态学与海洋学研究持续发展的基础上,分子机制及现代组学发展较迅速。然而, HAB发生的关键环境诱因和生物学(特别是生化与分子)机制仍然不是很清楚,缺乏一个可用来预测HAB暴发的关键因子。笔者认为,一方面是因为HAB的复杂性、种类及生态系统的特异性,另一方面是研究缺乏系统性与完整性。因此未来有必要加强对每一个重要的HAB原因种开展系统、持续的研究,类似于生物科学领域里的模式种研究,并且有必要开展综合性的研究,如实验室单种培养、中尺度模拟及现场生态研究相结合,整合现代组学、传统生理生态学和现场实时连续观测等技术。     

基于浮标资料的中国东部海域最大波高特征分析

利用原国家海洋局2010—2015年的浮标资料,计算渤、黄、东海有效波高和最大波高的线性关系,并通过1992—2011年共20 a的数值模拟有效波高资料计算中国东部海域各月的2.5 m、4 m、6 m以上最大波高频率和最大波高月极值分布。结果发现:中国东部海域由北至南,最大波高与有效波高的比值逐渐增大;最大波高频率和最大波高月极值空间分布均由渤海、黄海至东海逐渐增大,最大波高频率的极值12月最大,4或5月最小,最大波高月极值9月最大,4月最小。其时空分布表明:受不同天气系统影响,夏秋季台风较多,容易出现极值较大的最大波高;秋冬季冷空气较强,虽然最大波高极值相对较小,但大浪持续时间长、频率大、影响范围广。     

Growth inhibition and oxidative stress in two species of marine diatoms exposed to 1-phenylethanol

1-phenylethanol (1-PEA) is a flavor extensively used in the production of cosmetics, beverages, and food. The release of 1-PEA into coastal environments has aroused great concern. However, its potential effects on marine organisms are still unknown. In order to provide a better understanding of the ecological risks of 1-PEA in marine environments, this study determined the toxic effects of 1-PEA on two marine diatoms (Phaeodactylum tricornutum and Skeletonema costatum). The diatoms were grown in culture medium containing different concentrations of 1-PEA for 96 h. The contents of chlorophyll a, chlorophyll c, glutathione (GSH), malondialdehyde (MDA), and the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), were measured at the end of the exposure period. 1-PEA was shown to significantly inhibit the growth of diatoms, with 96-h EC50 values of 257.14 mg/Land 126.46 mg/L in P. tricornutum and S. costatum, respectively. In P. tricornutum, the levels of SOD, CAT, GPx, GSH, and MDA were stimulated only when 1-PEA concentrations were close to or greater than the 96-h EC50 value. However, in S. costatum, the activities of SOD and CAT, and the syntheses of two chlorophylls were inhibited even at an exposure concentration below the 96-h EC50 value. Taken together, these findings indicate a potential ecological risk by discharging 1-PEA into coastal areas and its species-specific toxic effects on marine organisms.     

基于PS-InSAR技术的地表沉降分析

由于传统测量手段对于地表沉降监测不足,PS-InSAR技术具有高空间分辨率和一定程度能克服时间、空间以及大气的影响等优势,因而逐渐成为一种大范围地表沉降监测的主要方法。本文利用PS-InSAR技术,通过SARscape软件对收集到的34幅覆盖日本千叶市地区的ENVISAT ASAR遥感影像进行沉降监测实验。实验结果表明:日本千叶市地区最大累计沉降量为58.965 mm,主要集中在城市地区,并且该地区的沉降和地下矿藏开发有关。     

基于FME实现CAD向GIS数据转换的关键技术研究

针对CAD数据与GIS数据的转换问题,本文探讨了CAD图层与GIS图层对应关系、CAD块转换、CAD注记转换、CAD扩展属性转换和CAD面转换5个技术点,研究成果应用于多个项目中,为实现CAD数据与GIS数据的转换提供了技术思路与技术指导。     

基于插入损失的鱼雷动力舱段振动传递评估方法

振动性能是评估鱼雷动力系统优劣的重要指标。将鱼雷动力舱段抽象为由振源、传递路径、响应点构成的集中参数动力学模型,在频域内对动力学方程推导,得到了系统的稳态响应幅值表达式。结合电气系统的插入损失概念,提出了适用于评估鱼雷动力舱段隔振元件效果的速度插入损失指标。结合工程问题给出了算例,表明在设计初期可以清晰地规划动力舱段的隔振结构的性能参数。