Estimating Cape hare occupancy and abundance in southern Tunisia using spotlighting data

This study outlines the importance of integrating spotlighting data and occupancy modelling to estimate the spatial occupancy, abundance and habitat preferences of Cape hares Lepus capensis in southern Tunisia. Exploring the spatial distribution pattern of this species is problematic because of its nocturnal and secretive behaviour. In order to overcome these constraints, we used spotlight surveys on equidistant points along tracks to collect presence/absence data. Using a likelihood-based approach, we estimated occupancy and relative abundance of Cape hare populations in three national parks: Sidi Toui, Bouhedma and Jbil. We also combined the three parks in a single area to represent ‘southern Tunisia’ for investigating the factors affecting its distribution pattern. Sidi Toui showed the highest occupancy and relative abundance values (88.84 ± 10.95% and 7.97 hares km^?2, respectively). Bouhedma was also recognised as high-quality hare habitat with occupancy and relative abundance values of 61.70 ± 11.70% and 2.85 hares km^?2, respectively. The lowest occupancy (49.65 ± 26.25%) and relative abundance (2.10 hares km^?2) estimates were encountered in Jbil. The combined parks model suggested that part of the distribution pattern of Cape hares can be explained by habitat quality. Spatial occupancy over southern Tunisia showed a positive relationship between its occurrence and the availability of Poaceae and Plantaginaceae.     

Evaluation of habitat requirements of small rodents and effectiveness of an ecologically‐based management in a hantavirus‐endemic natural protected area in Argentina

Hantavirus pulmonary syndrome is a severe cardio pulmonary disease transmitted to humans by sylvan rodents found in natural and rural environments. Disease transmission is closely linked to the ecology of animal reservoirs and abiotic factors such as habitat characteristics, season or climatic conditions. The main goals of this research were: to determine the biotic and abiotic factors affecting richness and abundance of rodent species at different spatial scales, to evaluate different methodologies for studying population of small rodents, and to describe and analyze an ecologically‐based rodent management experience in a highly touristic area. A 4‐year study of small rodent ecology was conducted between April 2007 and August 2011 in the most relevant habitats of El Palmar National Park, Argentina. Management involved a wide range of control and prevention measures, including poisoning, culling and habitat modification. A total of 172 individuals of 5 species were captured with a trapping effort of 13 860 traps‐nights (1.24 individuals/100 traps‐nights). Five rodent species were captured, including 2 hantavirus‐host species, Oligoryzomys nigripes and Akodon azarae. Oligoryzomys nigripes, host of a hantavirus that is pathogenic in humans, was the most abundant species and the only one found in all the studied habitats. Our results are inconsistent with the dilution effect hypothesis. The present study demonstrates that sylvan rodent species, including the hantavirus‐host species, have distinct local habitat selection and temporal variation patterns in abundance, which may influence the risk of human exposure to hantavirus and may have practical implications for disease transmission as well as for reservoir management.     

6种豆科绿肥植物与苹果树套种对果园土壤碳氮特征的影响

为探明豆科植物与果树套种对山地果园土壤碳氮含量特征的影响,本研究以无芒雀麦(Bromus inermis Ley-ss)为参比植物,以6种豆科作物[T1:箭筈豌豆(Vicia sativa L.)、T2:大鹁鸽灰豌豆(Pisum Large pigeon L.)、T3:绿豆(Phaseolusradiatus L.)、...     

Fish assemblage structure and aquatic pollution in a Brazilian stream: some limitations of diversity indices and models for environmental impact studies

Abstract –  The aim of this study was to describe and quantify the effect of aquatic pollution on the fish assemblage structure of the Corumbataí River (Brazil), by comparing two sites with different water quality characteristics. The results revealed that abundance of individuals was low at the polluted site (B). However, the two sites did not differ significantly in species richness (total and average). This fact contradicts theories stating that portions where the transverse area of the channel is larger should present a higher biological richness. It was also observed that the ichthyofauna of site B had higher evenness, and, consequently, a tendency to a higher diversity than that at site A. This demonstrates that diversity estimates should be used cautiously in environmental impact studies, as they do not necessarily indicate better conditions of communities living in more preserved environments.     

杭州植物园野生维管植物调查

杭州植物园内共有野生维管植物501种、4亚种、30变种、1变型（隶属于119科365属）。本文除反映了有关物种种群个体的多度之外，突出地反映了其中归化植物44种、珍稀濒危植物5种，该园建园以来分布区已明显收缩的植物35种、2变种，濒于绝灭的植物27种、2变种，已经绝灭的植物31种、1亚种和自园外传入的植物28种、1变型，并初步分析了该园内物种及其种群分布的动态变化及其原因。     

Applying a variable-shape spatial filter to map relative abundance of manatees (Trichechus manatus latirostris)

Presented is a modified spatial filter, called a variable-shape filter, that was used to transform a map of point locations of Florida manatees (Trichechus manatus latirostris) to a contoured surface illustrating relative abundance. Rather than having a fixed polygon shape and size as conventional filters do, this method preserves constant filter area but conforms polygon shape to include only the desired land-cover categories–in this study, water. Variable-shape filter polygons are formed by starting with the cell that the point is located in and then adding the nearest contiguous cells of the desired land-cover category to the polygon until the area requirement is reached. Surfaces generated using the variable-shape filter were compared to those created with a conventional, circular, fixed-shape filter. Four filter sizes, based on an analysis of manatee hourly travel rates estimated from satellite and radio telemetry data, were used. Filter sizes, defined in terms of a circle's radius, were 125 m, which was the 25th percentile of the cumulative manatee travel-rate distribution; 325 m, the 50th percentile; 800 m, the 75th percentile; and 3,950 m, the 99th percentile. The fixed-shape and variable-shape filters differed principally in how their results were influenced by land. The variable-shape filter, programmed to maintain constant area, estimated animals to occur farther from shore than the fixed-shape filter did. Fixed-shape filter polygons were occasionally divided by land barriers, such as peninsulas, resulting in calculations of relative abundance estimates that were near the visual sighting in terms of euclidian distance but far in terms of manatee travel. The variable-shape filter was preferable primarily because it was more sensitive to manatee ecology: only cells contiguous to the animal's mapped location were included in the filter calculations.     

桉树人工幼龄林根区和非根区土壤属性特征分析

深刻认识桉树人工幼龄林根区和非根区土壤属性特征对优化桉树营林措施具有重要意义。本研究以桉树人工幼龄林为研究对象,分析冬季和夏季桉树人工幼龄林根区和非根区0～20 cm和20～40 cm深度土壤理化性质、C∶N∶P化学计量比和细菌数量,探讨桉树人工幼龄林根区和非根区土壤理化属性和细菌丰度特征。结果表明,非根区土壤可溶性有机碳(DOC)、有机碳(SOC)、全氮(TN)含量显著大于根区土壤,非根区0～20 cm土壤可溶性有机氮(DON)和全磷(TP)含量显著大于根区土壤。夏季根区、非根区土壤含水量、DON、SOC和非根区DOC含量显著大于冬季;夏季桉树根区和非根区0～20 cm土壤TN、TP、土壤全钾含量显著低于冬季。参照全国土壤分级标准,冬季根区土壤SOC和夏季根区土壤TN含量为四级较缺乏水平。与全球森林土壤C∶N∶P平均值相比,桉树幼龄林根区土壤C∶N夏季高、冬季低,且根区土壤N∶P和C∶P均低于平均水平,推断桉树人工幼龄林冬季根区土壤存在C限制,夏季根区土壤存在N限制。桉树非根区0～20 cm土壤细菌丰度显著大于根区0～20 cm和非根区20～40 cm土壤。夏季土壤细菌丰度较冬季显著...     

黄海南部近岸水域棘头梅童鱼仔稚鱼的分布和漂移趋势

鱼类早期资源特征对鱼类种群的研究和渔业资源的评估管理具有极大的价值.实验于2019年3月—2020年1月在黄海南部近岸水域设置47个站点,每月大潮期间使用仔稚鱼网采集仔稚鱼,揭示了棘头梅童鱼仔稚鱼丰度的时空分布特征和漂移趋势,采用广义相加模型分析环境因子与之关联.调查共采集到棘头梅童鱼仔稚鱼2385尾,出现在6—10月...     

The dynamism fish-plant association: Ontogenetic variations in assemblage attributes in neotropical floodplain lakes

Structural habitat complexity provided by macrophytes is expected to increase richness and abundance of fish species. However, this topic is rarely investigated simultaneously at different periods of fish development. We sampled fish within macrophyte stands and in non-vegetated areas at floodplain lakes and tested the hypothesis that the presence of macrophytes increases abundance and species richness of fish, in addition to changes in species composition, at different periods of fish development. Our findings demonstrated that, in different period of fish development, the highest values of fish species richness and abundance were found at sites colonised by macrophytes. Similarly, changes in fish species composition were observed between habitats colonised by macrophytes and non-vegetated areas. Therefore, the results demonstrate that macrophyte presence plays an important role in regulating fish community structure at different periods of fish development.     

黄龙病对柑橘叶际微生物组的影响

为明确柑橘叶际微生物组对黄龙病发生的响应规律,采用荧光定量PCR技术检测采集柑橘叶片感染黄龙病菌的情况,通过扩增子测序分析法对PCR检测结果为阴性和阳性叶片的微生物群落进行比较,并通过相关性分析和网络分析对黄龙病菌和叶际微生物的相关性进行解析。结果显示,夏季采集的柑橘叶片中黄龙病菌的检出率为7.5%,而到秋季黄龙病菌的检出率上升到32.3%。黄龙病的发生显著改变了柑橘叶际细菌群落的组成和结构,对于细菌类群的丰度也有一定影响;而对叶际真菌群落的组成和结构无显著影响。黄龙病菌与叶际细菌存在普遍的负相关关系,正相关关系相对较少但相关性更强。黄龙病菌可能通过与厌氧棍状菌Anaerotruncus sp.、梭菌Clostridiales sp.、假单胞菌Pseudomonas sp.、鞘脂单胞菌Sphingomonas sp.、毛螺菌Lachnospiraceae sp.和链球菌Streptococcus sp.的负向互作对柑橘叶际整个细菌群落产生负影响。表明黄龙病发生对柑橘叶际真菌和细菌群落的影响规律不同,同时黄龙病菌可能通过与几种主要细菌的负向互作来实现对叶际微生物组的影响。