Overview of a Passive Tracking Index for Monitoring Wild Canids and Associated Species

Population density estimates for many animal species are often difficult or expensive to obtain, and they rely on assumptions that, if violated, result in unmeasurable estimation errors. Density estimates also may be unnecessary for research or management purposes, because an index that tracks changes in a population within appropriate time and geographic constraints could provide the information necessary to make management decisions or to evaluate the impact of a control program. We review research on a passive tracking index where observations are made on a series of tracking plots placed on lightly used dirt roads. The number of sets of tracks (individual intrusions) are recorded for each species of interest on each plot on consecutive days. The mean number of intrusions over the plots is calculated for each day for each species. The index is the mean of the daily means. These design and measurement methods present valuable advantages over most traditional tracking plot methods. Because no scents or baits are used as attractants, no conditioning of animals to the plots biases the results. This also permits multiple species, predator and prey alike, to be simultaneously monitored. Using the number of animal intrusions as observations produces results that are far more sensitive to change than tracking surveys where only presence or absence of spoor are recorded for each plot. Of particular importance, the statistical properties inherent to this data structure permit calculation of standard errors, confidence intervals and statistical tests, without subjectively subdividing the data.     

组分多度的相似相异百分率

根据组分多度比较分析的概念,建立了组分多度相似相异百分率的计算公式和两个详略不同的相似相异等级标准。根据对三尖杉属（Cephalotaxus）在云南的分布格局间的亲和性分析,表明组分多度比较分析具有了分析严密、计算简单和结果直观等优点。     

Processes of collating a European fisheries database to meet the objectives of the European Union Water Framework Directive

Abstract  FIsh Database of European Streams, a common database for the FAME project, was merged using existing data on electric fishing and environmental data. FIsh Database of European Stream is a relational database with eight tables. Metrics based on classification of fish species into guilds were calculated, and provided in separate tables. FIsh Database of European Stream contained information about 150 freshwater fish species, from 12 countries, 17 ecoregions, 40 main river regions, 2651 rivers and 8228 sites. Examples of data coverage and use are given. Relationships between environmental variables were illustrated using principal component analysis, which resulted in three environmental components – latitude, size and altitude. Environmental component scores were correlated with fish metrics used in the European Fish Index. Results exemplify how fish guilds reflect gradients in environmental variation. Benefits and problems concerning standardisation and data availability at the global level are discussed.     

不同类型水稻土微生物群落结构特征及其影响因素

选取基于我国土壤地理发生分类的不同类型土壤发育的四种水稻土,利用15N2气体示踪法测定生物固氮速率,采用实时荧光定量PCR(Real-time PCR)技术测定细菌丰度,通过16S rRNA基因高通量测序分析微生物群落组成和多样性.结果表明:变形菌门(Proteobacteria)、酸杆菌门(Acidobacteria...     

次生幼龄林封山育林后乔木层物种结构变化研究

1999年在浙江省仙居县俞坑村的封山育林区设置20 m×20 m的固定样地2块,对连续5年的调查数据进行统计分析,以其对次生幼林乔木物种结构变化进行研究.分析结果,乔木层物种丰富度指数增加了7～11,乔木物种增加了2～5科,3～8属.自然恢复为以壳斗科、杉科、山茶科、樟科、胡桃科、安息香科等物种为建群种或共建种的次生常绿阔叶林、针阔混交林.     

尼勒克县荒漠草地植物种类调查及分析

为了更好的保护尼勒克县荒漠草地植物资源,采用样方和植物踏查法对尼勒克县荒漠草地的植物种类进行调查研究。结果表明：尼勒克县荒漠草地有23科68属98种（亚种）植物,植物种类组成较丰富,有害植物少。藜科、菊科和禾本科为优势科,含有54种（亚种）植物;小型科和单科种类众多,单科植物有12种。按照经济类群划分,豆科植物占8.16%,禾本科植物占13.27%,藜科植物占27.55%,菊科植物占14.29%,莎草科植物占3.06%,杂类草占33.67%。按照饲用价值划分,优良占14.29%、良好占27.55%、一般占36.73%、差占16.33%、有毒占5.10%。     

辽宁省大豆田杂草发生与危害

采用倒置"W"九点取样法调查辽宁省大豆田杂草,明确了辽宁省大豆田杂草有19科35种,其中阔叶杂草占74.29%,禾本科杂草占14.29%,其他杂草占25.71%;一年生杂草占54.29%,多年生杂草占31.43%。相对多度达10%以上的杂草依次为藜、鸭跖草、稗草、苘麻、反枝苋、红蓼、马唐、铁苋菜、马齿苋和山苦菜。其中藜和鸭跖草相对多度在30%以上,为辽宁省大豆田杂草优势种群。     

长江口南支水域刀鲚仔稚鱼资源量的年度变化

为了进一步探明长江口南支刀鲚(Coilia nasus)仔稚鱼的分布和丰度变化,2018年6-10月在长江口南支设置8个站点,采用大型仔稚鱼网(口径1.3m,网目0.5mm)在每月大潮期间按月进行表层水平拖网调查,研究结果与2014年、2015年同水域和同期的研究结果比较,旨在揭示长江口南支刀鲚仔稚鱼资源的年度变化。本研究共拖网58网次,采集刀鲚仔稚鱼4611尾,平均密度0.123 ind./m3,体长范围3.1～61.74mm,发育阶段从前弯曲期到稚鱼期,其中前弯曲期仔鱼(3.1～18.12mm)最多,占总数86.19%,其次是弯曲期仔鱼(4.9～24.05mm),占8.5%,后弯曲期仔鱼(9.75～30.36mm)和稚鱼(24.22～61.7mm),分别占4.6%和0.72%。白天涨潮采集刀鲚仔稚鱼4271尾,平均体长11.18mm,平均密度0.169 ind./m3,退潮时采集336尾刀鲚仔稚鱼,平均体长10.52mm,平均密度(0.029 ind./m3)低于涨潮密度;St.8夜间涨退潮调查显示,涨潮密度(0.005 ind./m3)大于退潮密度(0.002ind./m3)。三年间刀鲚仔稚鱼发育阶段组成,2014年以卵黄囊期仔鱼为主,2015年和2018年均以前弯曲期仔鱼为主。各年刀鲚仔稚鱼出现的持续时间和高峰期基本相似,主要在6-8月出现,9-10月出现量极少。三年仔稚鱼密度分布表明,各站位点以及各月平均密度差异均不显著(P＞0.05)。     

怒江西藏段鱼类群落结构及多样性

为了探究怒江西藏段鱼类群落结构及多样性特征,于2017-2020年在怒江西藏段干流及主要支流设置9个调查站点进行了8次鱼类资源调查。调查共采集到鱼类23种,隶属于2目6科9属,其中怒江特有种有6种,外来鱼类5种。鱼类种类数分布总体上呈现随着海拔上升而逐渐减少的分布趋势。优势种为怒江裂腹鱼（Schizothorax nukiangensiss）、裸腹叶须鱼（Ptychobarbus kaznakovi）和热裸裂尻鱼（Schizopygopsis thermalis）,3种鱼类共占调查鱼类总生物量的96.28%,占生物总数的91.25%。群落多样性分析结果显示Shannon指数、Simpson指数、Margalef指数、Pielou指数范围分别为0.369~0.908、0.222~0.496、0.317~0.754和0.405~0.692,怒江西藏段鱼类群落多样性整体上处于较低水平。生态类型上分为底栖缓流型、底栖间隙型、急流吸附型及静水中层型4类,摄食类型基本上都为杂食性。下游察瓦龙乡与那曲大坝上游的鱼类物种组成相似性指数（11.76%）最低,支流左贡玉曲河与比如大坝下游的鱼类物种组成相似性指数（70.00%）最高。流域总体上处于中度干扰状态,上游大坝之间的河段及支流玉曲河处于较为严重的干扰状态。为了保护怒江西藏段鱼类多样性,降低区域内干扰,建议在玉曲河支流设立保护区,同时加强流域渔政管理,规范放生行为,做好流域开发的生态保护修复与预案研究。     

Quantifying fish avoidance of small acoustic survey vessels in boreal lakes and reservoirs

Mobile hydroacoustic surveys are increasingly used to assess the distribution and abundance of freshwater fish; yet, fish may avoid moving vessels, potentially introducing bias in these assessments. In this study, avoidance in boreal lakes and reservoirs was quantified by developing a simple method based on paired drift:drift (D:D) and drift:motor (D:M) transects. Two systems in eastern Manitoba, Canada were studied: Lac du Bonnet reservoir and Nopiming. Acoustic data were collected using a digital DTX echosounder (BioSonics, Seattle, WA, USA), with a downward facing 200‐kHz split‐beam transducer, deployed from 5.5‐m vessels (Boston Whalers) modified for acoustic research. An avoidance coefficient (Ac) was developed based on comparisons of acoustic fish densities while the vessel moved over the same transects by drifting, and by motoring at survey speeds. Ac did not differ significantly from 1 (no avoidance) at Nopiming (median of 0.81, n = 13), but did at Lac du Bonnet (median of 0.51, n = 31, P < 0.05). Variability in Ac was as high in transect pairs and was unrelated to fish depth (mean 6.9 m at Lac du Bonnet; 13.1 m at Nopiming) or survey speed (up to 3.70 m·s^?1, 7 knots). Results indicated that fishes did not dive in the presence of the motoring vessel, nor was avoidance size‐based. We did not detect any evidence of fish attraction to our drifting vessel. Our results suggest that boat avoidance during acoustic surveys of shallow boreal lakes may vary in relatively similar water bodies but can be quantified experimentally.