Structure and diversity of Erica ciliaris and Erica tetralix heathlands at different successional stages after cutting

In NW Europe, it is known that cutting is a useful tool for managers with regard to decisions about the conservation and management of wet heathlands. Nevertheless it is rarely described quantitatively in the international literature. In Spain, knowledge about this is scarce or lacking. In this study, twenty communities were selected in Galicia (NW Spain) that would represent from one to four stages of vegetation development after cutting. Two 5?×?5?m plots were established for each stage to characterise the vegetation on the basis of its species composition, frequency values, vertical structure and linear cover features. The Diversity Shannon index was calculated and multivariate analyses were performed. As succession advanced, notable changes were produced in the cover of dominant species, Erica ciliaris and Ulex gallii in the first stages and Erica tetralix and Genista berberidea in mature ones. Also, the species richness decreased because of the reduced number of herbs species in the mature stages and, finally, the cover values are indicators of the degree of vegetation development, together with the other parameters of height, overlayering or diversity. Cutting is a useful tool for management of heathlands because the existence of vegetation units belonging to different succession stages increases the internal diversity of communities. On the other hand, the vertical and horizontal structure reflects the formidable resilience of the vegetation community to this practice. This study offers a global vision of the dynamics of wet heathlands after cutting, with very useful ecological information that can be used by the people responsible for their management.     

环境的不确定性对声纳作用距离预报的影响

由于海洋环境的复杂性,声速梯度存在一定的不确定性.用蒙特卡洛方法对声速梯度进行模拟统计,并用WKBZ方法计算传播损失,得出各个距离上传播损失的概率分布直方图,由此可以导出声纳作用距离的概率分布直方图.相对于传统的声纳作用距离预报结果,文中给出的作用距离预报结果是一个满足某一分布的随机变量,而非某一个单一确定的值,为作用距离的预报提供了概率的依据.     

Lead isotope ratios in lichen samples evaluated by ICP-ToF-MS to assess possible atmospheric pollution sources in Havana,Cuba

Epiphytic lichens, collected from 119 sampling sites grown over “Roistonea Royal Palm” trees, were used to assess the spatial distribution pattern of lead (Pb) and identify possible pollution sources in Havana (Cuba). Lead concentrations in lichens and topsoils were determined by flame atomic absorption spectrophotometry and inductively coupled plasma (ICP) atomic emission spectrometry, respectively, while Pb in crude oils and gasoline samples were measured by ICP-time of flight mass spectrometry (ICP-ToF-MS). Lead isotopic ratios measurements for lichens, soils, and crude oils were obtained by ICP-ToF-MS. We found that enrichment factors (EF) reflected a moderate contamination for 71% of the samples (EF > 10). The ²⁰⁶Pb/²⁰⁷Pb ratio values for lichens ranged from 1.17 to 1.20 and were a mixture of natural radiogenic and industrial activities (e.g., crude oils and fire plants). The low concentration of Pb found in gasoline (<7.0 μg L^?1) confirms the official statement that leaded gasoline is no longer used in Cuba.     

新安江水库悬浮颗粒物时空分布、沉降通量及其营养盐效应

为分析降雨入流影响下水库悬浮颗粒物的时空分布及沉降特征,在华东地区最大水库新安江水库(千岛湖)的河流区、过渡区和湖泊区(分别对应街口、小金山和大坝这3个水质断面)布设水体沉降物自动捕获器和水质高频自动监测浮标,结合定期水样采集分析,开展了为期1 a的水体颗粒物沉降通量及其营养盐效应观测研究.结果发现,水库水体浊度、悬浮颗粒物浓度(SS)、颗粒物沉降通量与降雨量、入库流量极显著相关(P<0.01),其中浊度与SS的相关性最好(R²=0.86);在降雨较多的春夏季,SS空间差异明显(河流区>过渡区>湖泊区),而秋冬空间差异不大;颗粒物沉降通量具有明显的时空异质性,空间上河流区>过渡区>湖泊区[分别为27.82、 4.34和0.26 g·(m²·d)^-1],时间上春夏季>秋冬季;结合全湖60个点位四季悬浮物浓度调查估算,全库颗粒物沉降通量为2.57×10⁶ t·a^-1,其中春夏季沉降通量高于秋冬季;街口、小金山和大坝捕获沉降物中颗粒态氮含量(PN)...     

上海环城林带植物群落景观美学评价

以上海环城林带为对象,采用美景度评判法进行不同植被类型的景观评价,评价分为林内景观和林外景观2个空间层次,分别在春、夏、秋、冬4个季节进行。结果表明,林内景观平均值和林外景观的美景度都表现为夏季最高,冬季最低。在不同植被类型的林内景观中,落叶针叶林在不同季节均表现出最高的美景度,竹林的美景度最低;针叶林中,常绿针叶林的美景度四季均低于落叶针叶林;阔叶林中,落叶阔叶林的美景度在春季和夏季高于常绿落叶林,常绿阔叶林在秋季和冬季高于落叶阔叶林;混交林中,除秋季外,针阔混交林的美景度均高于常绿落叶阔叶混交林。     

Mangrove mapping in Ecuador: The impact of shrimp pond construction

A cooperative mangrove mapping project between the Ecuadorian Center for Remote Sensing (CLIRSEN) and the University of Delaware was begun in August 1982. The objectives of the project were to create historical maps of mangrove ecosystem extent and change, while transferring aerial photographic interpretation techniques to Ecuadorian personnel. The result of this cooperation was a series of three 125,000 scale maps of historical mangrove extent and change from 1966 to 1982 in the southern Gulf of Guayaquil. This multitemporal study showed a 16% decrease in mangrove extent and a 27% increase in shrimp pond development. If these rates of change prevail into the future, mangroves in Ecuador will reach parity with shrimp ponds in 1984 and completely disappear by mid-1990. Recognizing the significance of this loss to shellfish and fish production along the coast, Ecuadorian scientists at CLIRSEN have subsequently initiated a nationwide mangrove mapping program to create a historical base for future mangrove management strategies.     

猪粪堆肥中一株溶磷菌的筛选鉴定及溶磷能力初步测定

从猪粪堆肥中分离纯化得到一株具有较强溶磷能力的菌株PSM-1,进行了形态学和分子生物学鉴定,研究了其溶磷能力和遗传稳定性.结果表明:通过菌落形态和ITS基因序列分析鉴定,菌株PSM-1为产黄青霉(Penicillium chrysogenum);在3种不同无机磷源液体培养基中其溶磷量依次为Ca3(PO4)2(138.36 mg·L-1)Fe PO4(117.38 mg·L-1)Al PO4(113.76 mg·L-1),且PSM-1的溶磷量均与培养液p H值呈现出显著负相关性;以葡萄糖为碳源、硝酸铵为氮源时,菌株PSM-1的溶磷量最高可达195.67 mg·L-1,比初始有效磷高141.42%;该菌株对碳源和氮源的利用效率分别依次为:葡糖糖蔗糖麦芽糖淀粉,硝酸铵硝酸钾硫酸铵草酸铵;经过20次传代培养后PSM-1的溶磷量保持在(124.54±3.50)mg·L-1,说明其溶磷遗传稳定性良好.研究表明:PSM-1菌株具有良好的溶解无机磷的能力,在土壤微生态改良方面具有重要的应用潜力.