土壤质地与埋深对白刺群落主要伴生植物出苗的影响研究

在田间条件下,研究了3种土壤质地与5个埋深对白刺群落主要伴生植物苦豆子、黄花矶松、沙蒿、油蒿和红砂出苗的影响,为白刺群落恢复、优良植物的筛选及其种群扩展提供理论依据与技术支撑。试验研究表明,尽管白刺群落主要伴生植物在田间的出苗率均较低,但各植物的出苗能力明显不同。土壤质地仅对伴生植物苦豆子、沙蒿和黄花矶松出苗有显著影响,而埋深处理对伴生植物出苗均有显著影响。不同土壤质地与埋深处理的平均出苗率以苦豆子最高,红砂、沙蒿和黄花矶松次之,油蒿最低;不同土壤质地的最高出苗率,沙土以沙蒿最大,沙壤土以黄花矶松最大,黏土以红砂最大;出苗适宜埋深,苦豆子为1.0~2.0 cm,沙蒿、黄花矶松、油蒿和红砂为0.5 cm。研究结果表明,选择适宜的植物及其人工促进技术对退化白刺固沙植被的恢复至关重要。     

Fluoride,nitrate and water hardness in groundwater supplied to the rural communities of Ensenada County,Baja California,Mexico

The hydrogeochemistry of 26 wells belonging to ten different aquifers in the county of Ensenada, Baja California, is studied. These wells are all used to supply the rural communities in the region, which comprise ~37,000 inhabitants, excluding the city of Ensenada. High total dissolved solids (TDS) concentrations (maximum 7.35 g l⁻¹) indicate that salt is a ubiquitous contaminant in the aquifers due to seawater intrusion. The aquifers that support extensive agriculture activities (Maneadero, San Quintín, San Simón and El Rosario) are characterized by higher N–NO₃ concentrations (maximum 20 mg l⁻¹) derived from fertilizers. Fluoride concentrations exceed the 1.5 mg l⁻¹ Mexican official limit in only four wells. The enrichments of F⁻ in the southern aquifers are thought to be associated to water–rock interactions controlled mainly by Na–Ca equilibrium reactions with fluorite, as suggested from high dissolved Na concentrations in these waters. In the northern aquifer of Maneadero, no enrichment of Na is found and a geothermal source for F⁻ is likely. Water is hard to moderately hard, with Ca/Mg ratios >1. Although drinking water directly from the tap is not a common practice in these localities, most sources have concentrations of major ions and TDS that exceed the Mexican official limits.     

Keeping things in order: multivariate direct gradient analysis of a strongly fluctuating benthic community

Two spatial surveys of the macrobenthos of an estuarine intertidal area, the Oosterschelde in the southwestern part of The Netherlands, were conducted in different years. In the period between the surveys changes in the hydrodynamics of the estuary took place as a result of the construction of a storm-surge barrier. The works reduced the tidal volume in the basin and as a consequence the altitude of the tidal flats decreased by approximately 0.1 to 0.2 m. Considerable differences in species densities were found between the two surveys, but these large differences could not be explained by changes in the ‘spatial' environmental variables (such as altitude) that were taken into account in a direct gradient analysis. Unknown and ‘only-to-time-related' (e.g. weather-related) factors had considerably influenced species abundance. This implies that the impact of the works on the macrobenthos could not be evaluated on the basis of observed species densities in the before- and after-the-works surveys. Generally, it implies that even if the levels of future ‘spatial' environmental variables are known, direct gradient analysis based on a single survey cannot be used for prediction of future densities in absolute terms in such strongly fluctuating communities. Yet, the gradient analyses for the two years revealed rather similar estimates of the major environmental gradients. The same was true for the parameters that described the relative change in species densities in response to a change in the environmental gradient levels. Hence the most appropriate way of evaluating the changes that have occurred in the benthic community as a result of the works was in terms of the observed changes in the ‘spatial' environmental gradient levels. The levels of the first environmental gradient, which was strongly related to the sediment structure, did not change between years. Levels of the second gradient, which could be interpreted as a tidal zone gradient, decreased. This suggests that the works particularly affected taxa that are strongly related to this second gradient, such as Corophium living in the upper tidal areas and Nephthys living in the lower tidal zone.     

Determination of the submerged macrophyte coverage of greifswalder bodden

The extent to which a water body can support submerged macrophytic vegetation provides an indicator of its degree of eutrophication. Regular, quantitative assessment of macrophyte populations enables changes in the trophic state of the system to be observed. A combination of aerial photography and underwater videography has proved to be an efficient method for calculating macrophyte coverage of large coastal areas.     

Insect communities of Phragmites habitats used for sewage purification: Effects of age and area of habitats on species richness and herbivore-parasitoid interactions

In 1994, 28 sewage purification plants based on common reed Phragmites australis were analyzed, to study fragmentation effects on diversity and on food web structure of insect communities. Purification plants differed in age (2 to 11 years) and area (10 to 2,500 m²). Both age and area were significantly correlated with species richness of herbivores. Populations of the two most abundant herbivores, the gall makers Lipara pullitarsis (Diptera, Chloropidae) and Giraudiella inclusa (Diptera, Cecidomyiidae), increased significantly with age and size of the Phragmites habitats, i.e. the purification plants. Incidence curves showed that only habitats older than 6 years and larger than 100 m² have a 50% probability of finding these two most abundant gall makers, and can correspondingly be considered to contribute to insect species conservation. Natural enemies were even more susceptible to habitat fragmentation than their phytophagous hosts or prey, thereby hampering possible biocontrol. Percent parasitism of both the Lipara and Giraudiella gall makers significantly increased with habitat age.     

数字地球的体系研究

通过对地学空间信息研究背景及其内容的分析,认为数字地球是人类空间信息革命的序幕。并结合数字地球的关键技术,提出了数字地球的全球层、区域层以及国家层的实现模式。文章还对数字地球的应用领域展开了讨论,认为数字地球是人类下个世纪经济增长的关键,并是人类适居社区等建设的决策信息支柱。     

住区环境对居民主观幸福感的影响机制研究——以深圳混合居住区为例

随着中国特色社会主义新时代人民对美好生活的向往与日俱增,配建房居住群体作为一类“夹心层”群体,其住区环境和主观幸福感理应得到充分重视。论文以深圳市混合居住区为例,揭示配建房住区环境对居民主观幸福感的影响机制。针对3个典型住区开展问卷及访谈调研,并构建结构方程模型,将地方感和房屋类型分别作为住区环境影响居民主观幸福感的中介变量和调节变量。研究结果表明：(1)总的看,住区环境对居民主观幸福感具有显著的直接影响;分维度看,社会环境对主观幸福感具有直接影响,而建成环境中,小区环境、社区环境和住房环境对主观幸福感影响均不显著;(2)由中介效应看,社会环境通过建立居民地方感间接影响主观幸福感;(3)由房屋类型看,相较保障房住户,人才房住户主观幸福感受社会环境影响强度更大。综合来看,研究结果能够为完善配建房制度提供科学决策支持。     

贵州关岭县喀斯特峰丛石漠区苔藓群落生态特征

为了了解喀斯特峰丛石漠化区苔藓植物的种类和群落特征,本文选取贵州省安顺市关岭县喀斯特峰丛石漠化区的三种典型生境（裸地、人工植被和自然植被）,对苔藓植物进行样地调查,并利用种间相遇几率（PIE）、生态优势度、Shaanon-Wiener信息指数(衡量生态位宽度)和Morisita-Horn指数(衡量生态位重叠)来分析该区苔藓植物群落的组成、分布规律及生态特征。结果表明:（1）该区苔藓植物共有11科17属22种,真藓科为优势科,苔藓植物群落有19个类型。（2）苔藓群落PIE值与植被覆盖度呈正比,与岩石裸露率呈反比,自然植被生境的苔藓群落PIE值高于人工植被和裸地生境,但研究区苔藓群落PIE总体偏低,反映了喀斯特峰丛地区恶劣的生境条件。（3）研究区内卷叶湿地藓群落(Hyophiletum)、直蒴卷柏藓群落(Racopietum)和皱叶牛舌藓群落(Anomodetum)有着较高的生态优势度和生态位宽度,并且与其它苔藓群落的生态位重叠值很高。表明这三种苔藓群落对不同类型的峰丛石漠化生境都有着较好的适应能力,能够很好地与其它苔藓群落互利共生。      

北部湾典型红树林岛群生态系统的结构特征与碳储量研究（英文）

通过研究北部湾海域龟仙岛和背风墩红树林岛群生态系统的结构特征与碳储量,为红树林保护及生态补偿提供科学依据。本文以无人机遥感影像和样地调查为数据源,采用面向对象的多尺度分割算法提取红树林群落类型信息,借助单因素方差分析、优势种分析、多样性分析等方法来分析红树林群落的结构特征,基于红树植物的异速生长方程,得出了不同海岛红树林生态系统碳密度和碳储量。(1)龟仙岛和背风墩岛屿群落约 27.10 ha,其中,红树林面积约 11.20 ha,占岛群总面积的 41.32%,红树林群落广泛分布于岛屿周围的浅海滩涂区域;(2)主要群落类型有桐花树群落、秋茄+桐花树群落、白骨壤+桐花树群落和白骨壤群落,物种多样性指数较低;(3)在红树林的生物量中,白骨壤最高(18.52 kg 株^–1),秋茄次之(7.84 kg 株^–1),桐花树最小(3.85 kg 株^–1);(4)红树林碳密度差异显著,秋茄的碳密度最高(148.03 t ha^–1),其次是白骨壤(104.79 t ha^–1),桐花树最小(9...     

天然气水合物分解及其生态环境效应研究进展

了解大陆／大洋边缘地区天然气水合物形成与分解及其在海底沉积物、水体及海底化学自氧生物群落中的一系列物理、化学及生物作用有助于我们在全球和区域尺度上探讨天然气水合物分解对气候变化的影响;天然气水合物在碳循环中的作用和大陆边缘流体活动与物质交换机制等问题。从水合物分解与全球变暖、贫／缺氧甲烷氧化作用、自生矿物沉淀、化学自养生物群落等方面综述了水合物的环境生态效应研究进展。天然气水合物的形成／分解及 其对海洋乃至全球环境生态变化的影响,深刻地反映了地球上岩石圈、水圈、大气圈和生物圈之间相互联系与相互作用,生物,特别是微生物对全球CH 4的平衡和自生矿物沉淀至关重要。