Tawny Owl Strix aluco as an indicator of Barn Owl Tyto alba breeding biology and the effect of winter severity on Barn Owl reproduction

In the temperate zone, food availability and winter weather place serious constraints on European Barn Owl Tyto alba populations. Using data collected over 22 years in a Swiss population, we analysed the influence of early pre‐breeding food conditions and winter severity on between‐year variations in population size and reproductive performance. To estimate pre‐breeding food conditions, we attempted a novel approach based on an index that combines Tawny Owl Strix aluco reproductive parameters and the occurrence of wood mice Apodemus sp. in their diet. Tawny Owls breed earlier in the season than Barn Owls and are strongly dependent on the abundance of wood mice for breeding. This index was strongly positively associated with the number of breeding pairs and early breeding in the Barn Owl. Winter severity, measured by snow cover and low temperatures, had a pronounced negative influence on the size of the breeding population and clutch size. Food conditions early in the breeding season and winter severity differentially affect the Barn Owl life cycle. We were able to use aspects of the ecology and demography of the Tawny Owl as an indicator of the quality of the environment for a related species of similar ecology, in this case the Barn Owl.     

Factors affecting spontaneous vocal activity of Tawny Owls Strix aluco and implications for surveying large areas

To use vocalizations properly for the estimation of owl population size, it is important to identify how environmental factors affect owl calling behaviour. Here, we analyse how intrinsic and extrinsic factors modify the vocal activity of Tawny Owls Strix aluco in two areas of northern Spain. From March 2013 to May 2015, we radiotracked 20 Tawny Owls and also undertook a systematic survey in which we collected data on spontaneous vocal activity (hoot/call) of the tagged owls, plus their mates and neighbours (36 untagged owls). After 223 nights in Valle de Mena and 224 in Duranguesado we obtained a total of 8791 records of vocal activity. The annual proportion of surveys on which an owl called was 6.3% and did not differ between the study areas. Vocal activity of Tawny Owls varied with sex, annual cycle stage and weather. Male owls were significantly more vocal than females year‐round, and vocal activity peaked during the incubation and post‐breeding periods. Wind and rain adversely affected vocal activity of both sexes throughout the year. Tagged owls were detected more often than untagged owls, which we interpret as an observer effect because the systematic survey ensured that short distances to tagged owls increased the probability of detecting vocal activity. In fact, 2.8% of variation in vocal activity was due to detectability differences between tagged and untagged owls. We conclude that if fieldwork is carried out during the optimum period of the year for vocal detection (i.e. incubation, which in our case was around mid‐April), and under good weather conditions (dry and calm nights), censuses based on spontaneous vocal activity would detect only approximately 12% of the true Tawny Owl population.     

Predicting probability of occurrence and factors affecting distribution and abundance of three Ozark endemic crayfish species at multiple spatial scales

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The extent of shifts in vegetation phenology between rural and urban areas within a human‐dominated region

Urbanization is one of the major environmental challenges facing the world today. One of its particularly pressing effects is alterations to local and regional climate through, for example, the Urban Heat Island. Such changes in conditions are likely to have an impact on the phenology of urban vegetation, which will have knock‐on implications for the role that urban green infrastructure can play in delivering multiple ecosystem services. Here, in a human‐dominated region, we undertake an explicit comparison of vegetation phenology between urban and rural zones. Using satellite‐derived MODIS‐EVI data from the first decade of the 20th century, we extract metrics of vegetation phenology (date of start of growing season, date of end of growing season, and length of season) for Britain's 15 largest cities and their rural surrounds. On average, urban areas experienced a growing season 8.8 days longer than surrounding rural zones. As would be expected, there was a significant decline in growing season length with latitude (by 3.4 and 2.4 days/degree latitude in rural and urban areas respectively). Although there is considerable variability in how phenology in urban and rural areas differs across our study cities, we found no evidence that built urban form influences the start, end, or length of the growing season. However, the difference in the length of the growing season between rural and urban areas was significantly negatively associated with the mean disposable household income for a city. Vegetation in urban areas deliver many ecosystem services such as temperature mitigation, pollution removal, carbon uptake and storage, the provision of amenity value for humans and habitat for biodiversity. Given the rapid pace of urbanization and ongoing climate change, understanding how vegetation phenology will alter in the future is important if we wish to be able to manage urban greenspaces effectively.     

城市花粉致敏植物种类构成、分布与潜在危害评估——以深圳市为例

气传致敏花粉会引发过敏症,且可通过每年在花粉季的反复接触逐渐加重,危害人体健康,严重时甚至危害生命。花粉致敏植物在城市中被广泛引种栽培,导致城市花粉症患者数量激增。以深圳市为案例,基于建成区600个样地的实地调查数据,分析花粉致敏植物的种类构成与时空分布,通过构建花粉浓度及花粉致敏危害潜力计算公式,评估花粉致敏危害潜力及其分布特点。结果显示：①调查记录到深圳市建成区花粉致敏植物46科92属186种,其中外来种占43.37%,其中美洲、亚洲和大洋洲来源占国外外来种的81.00%。花粉致敏植物种数以公园绿地最多,达126种。植物花粉致敏等级以Ⅰ级为主,达154种。②花粉致敏植物的盛花期为春夏季,占全年累计开花种数的65.02%。最高峰出现在8月,开花种数达92种。 ③花粉浓度潜力最高值也出现在8月,占全年总值的12.13%。豆科和禾本科植物贡献比例较大,分别占乔木和草本总值的40.86%和64.13%。龙岗区花粉浓度潜力占比较高,占各季花粉量的26.06%-29.42%。④冬春两季各样地花粉致敏危害等级均不高,但夏秋季有些样地达到二级重度危害。罗湖区调查样地全年花粉致敏危害等级均较低,光明区在春夏秋季致敏危害等级皆较高。高危害等级样地主要出现在附属绿地及公园绿地。⑤花粉致敏植物防控措施情景模拟结果,去除主要花粉致敏植物种类比降低所有花粉致敏植物的花粉浓度潜力更有效。本研究为城市花粉致敏植物的管理、规划、养护和研究提供参考。     

Spatial autocorrelation in predictors reduces the impact of positional uncertainty in occurrence data on species distribution modelling

Aim To investigate the impact of positional uncertainty in species occurrences on the predictions of seven commonly used species distribution models (SDMs), and explore its interaction with spatial autocorrelation in predictors. Methods A series of artificial datasets covering 155 scenarios including different combinations of five positional uncertainty scenarios and 31 spatial autocorrelation scenarios were simulated. The level of positional uncertainty was defined by the standard deviation of a normally distributed zero‐mean random variable. Each dataset included two environmental gradients (predictor variables) and one set of species occurrence sample points (response variable). Seven commonly used models were selected to develop SDMs: generalized linear models, generalized additive models, boosted regression trees, multivariate adaptive regression spline, random forests, genetic algorithm for rule‐set production and maximum entropy. A probabilistic approach was employed to model and simulate five levels of error in the species locations. To analyse the propagation of positional uncertainty, Monte Carlo simulation was applied to each scenario for each SDM. The models were evaluated for performance using simulated independent test data with Cohen’s Kappa and the area under the receiver operating characteristic curve. Results Positional uncertainty in species location led to a reduction in prediction accuracy for all SDMs, although the magnitude of the reduction varied between SDMs. In all cases the magnitude of this impact varied according to the degree of spatial autocorrelation in predictors and the levels of positional uncertainty. It was shown that when the range of spatial autocorrelation in the predictors was less than or equal to three times the standard deviation of the positional error, the models were less affected by error and, consequently, had smaller decreases in prediction accuracy. When the range of spatial autocorrelation in predictors was larger than three times the standard deviation of positional error, the prediction accuracy was low for all scenarios. Main conclusions The potential impact of positional uncertainty in species occurrences on the predictions of SDMs can be understood by comparing it with the spatial autocorrelation range in predictor variables.     

城市公共绿地常见木本植物组成对鸟类群落的影响

快速城市化背景下, 城市公共绿地已经成为重要的鸟类栖息地, 其中的木本植物群落构成对鸟类群落结构有显著影响, 研究木本植物配置与鸟类多样性的关系对提升城市公共绿地作为鸟类栖息地的生态服务功能有重要的理论和应用价值。我们于2009–2010年间在上海市滨江森林公园就木本植物和鸟类群落的相互关系展开研究。样线法结合样点调查共记录到鸟类10目25科64种5,368只(次), 鸟类多度全年变化显著, 峰值分别出现在4月和11月。丰富度全年也呈现双峰型变化, 峰值出现在4月和12月。全年鸟类多样性(Simpson指数)差异显著, 10月最高, 8月最低。样方调查共记录到77种木本植物, 其中有14种(乔木9种、灌木5种)出现率超过5个样方, 定义为常见种, 其果期主要集中在9月到翌年2月, 其上常见林业致病害虫的发生盛期集中在5–11月。主成分分析显示, 常见木本植物上观察到的鸟类可划分为8个鸟类集团, Spearman秩相关检验显示秋冬季常见木本植物果期与植食性、肉食性、食虫性、杂食性等多个鸟类集团的多度均呈显著正相关。说明在秋冬季鸟类迁徙高峰期不同鸟类集团均能获得丰富的食物资源。就常见木本植物对鸟类群落的重要值进行排序, 结果显示, 大叶杨(Populus lasiocarpa)、枫杨(Pterocarya stenoptera)、香樟(Cinnamomum camphora)等乔木对鸟类重要值较高, 而灌木层对鸟类的重要性整体偏低, 说明滨江森林公园的灌木层作为鸟类栖息地的功能建设尚需加强。根据以上研究结果, 我们提出了提高上海城市公园鸟类多样性的植被配置建议。     

Diversity of Central European urban biota: effects of human‐made habitat types on plants and land snails

Aim Urbanization is associated with strong changes in biodiversity, but the diversity of plant and animal assemblages varies among urban habitats. We studied effects of urban habitats on the diversity of vascular plants and land snails in 32 large cities. Location Central Europe, Belgium and the Netherlands. Methods The species composition of all vascular plants that had not been planted by humans, and all land snails, was recorded in seven 1‐ha plots within each city. Each plot contained one urban habitat type representing a different disturbance regime: historical city square, boulevard, residential area with compact building pattern, residential area with open building pattern, park, early successional and mid‐successional site. For each plot, we obtained temperature and precipitation data. The effects of climate and habitat types on species composition were quantified using ordination methods with an adjusted variation partitioning algorithm. Differences in species composition among urban habitats were described using statistically determined diagnostic species, and differences in alpha, beta and gamma diversity were quantified. Results A total of 1196 plant and 87 snail species were recorded. Habitat type explained higher proportions of the total variation in both plant and snail species composition (11.2 and 8.2%, respectively) than did climate (4.6 and 6.3%). For both taxa, the main differences in species composition were observed between strongly urbanized sites in city centres and early successional and mid‐successional sites. For vascular plants, the number of species was lowest in city squares and boulevards, and highest at successional sites and in residential areas with compact building patterns. Beta diversity of vascular plants calculated for the same habitat types among cities was highest for squares and successional sites. The number of snail species was lowest in city squares and at early successional sites, and highest at mid‐successional sites. The highest beta diversity of snail assemblages among cities was observed within the city square and early successional habitat types, and the lowest within residential area habitat types. Main conclusions Urban habitats differ notably in the diversity of their vascular plant flora and land snail fauna. Understanding the habitat‐related biodiversity patterns in urbanized landscapes will allow projections of future impacts of urban land‐use changes on the biota.     

Evidence of niche shift and global invasion potential of the Tawny Crazy ant,Nylanderia fulva

Analysis of an invasive species' niche shift between native and introduced ranges, along with potential distribution maps, can provide valuable information about its invasive potential. The tawny crazy ant, Nylanderia fulva, is a rapidly emerging and economically important invasive species in the southern United States. It is originally from east‐central South America and has also invaded Colombia and the Caribbean Islands. Our objectives were to generate a global potential distribution map for N. fulva, identify important climatic drivers associated with its current distribution, and test whether N. fulva's realized climatic niche has shifted across its invasive range. We used MaxEnt niche model to map the potential distribution of N. fulva using its native and invaded range occurrences and climatic variables. We used principal component analysis methods for investigating potential shifts in the realized climatic niche of N. fulva during invasion. We found strong evidence for a shift in the realized climatic niche of N. fulva across its invasive range. Our models predicted potentially suitable habitat for N. fulva in the United States and other parts of the world. Our analyses suggest that the majority of observed occurrences of N. fulva in the United States represent stabilizing populations. Mean diurnal range in temperature, degree days at ≥10°C, and precipitation of driest quarter were the most important variables associated with N. fulva distribution. The climatic niche expansion demonstrated in our study may suggest significant plasticity in the ability of N. fulva to survive in areas with diverse temperature ranges shown by its tolerance for environmental conditions in the southern United States, Caribbean Islands, and Colombia. The risk maps produced in this study can be useful in preventing N. fulva's future spread, and in managing and monitoring currently infested areas.     

斑块面积对城市绿地降温效应的影响研究进展

在气候变化和快速城市化的双重影响下,全球城市面临日益加剧的热岛效应。绿地能够有效改善城市热环境。城市土地资源紧缺,优化绿地布局,使有限面积的绿地发挥更大的降温效果具有重要的理论意义和实践价值。其中,如何设置绿地斑块大小则是优化绿地布局的首要考虑因素之一。从斑块和景观的尺度总结了现有绿地斑块大小对其降温效应影响的研究进展,结果表明：1）在斑块尺度,随着绿地斑块面积增加,绿地的降温效应相应增加,但增加的趋势为非线性变化,表现为温度随绿地斑块面积的增加先下降,后趋于平稳,表明可能存在降温效率（单位面积绿地降温能力）最强的斑块大小;2）在景观尺度,绿地斑块大小在空间上的配置对热环境的影响研究结果存在差异,尚无一致性定论。基于已有研究,本文指出了现有绿地斑块大小对其降温效应影响研究中的问题与不足：1）主要关注绿地斑块大小与温度的统计关系,缺乏对其具体影响过程和内在机制的深入探讨;2）更多关注地表温度,而对与人体舒适度和健康直接相关的其他热环境指标的研究较少;3）研究中缺少对城市中数量巨大,分布最广的小型绿地斑块的考量。未来的研究应加强从遮阴和蒸腾等降温过程深入解析绿地斑块大小对热环境影响的内在机理机制,从降温效率的角度,探讨是否存在最优的斑块大小,并进一步探讨绿地周围建筑环境对绿地斑块大小与其降温效应关系的影响,为优化城市绿地分布,改善城市热环境提供科学依据。     

Compositional similarity and the distribution of geographical range size for assemblages of native and non-native species in urban floras

There is evidence that, within a region, non-native species introduced from nearby sources (extralimital native) promote homogenization and non-native species introduced from distant sources (exotic) promote differentiation of species composition. A possible explanation for these associations is that they are related to differences in the distribution of geographical range size. We test this by examining geographical ranges, delineated within a defined region, for assemblages of vascular plants in eight urban floras in the USA. Across floras, native species had the largest, least variable ranges and the greatest proportion of shared species. Exotic species had the most variable ranges with concentrations of species with small and large ranges and the lowest proportion of shared species. Extralimital natives had concentrations of species with intermediate-sized ranges and intermediate proportions of shared species. These results suggest that patterns of compositional similarity were associated with the relative strength and equality of two opposing patterns within species range size distributions: species with small vs. large ranges. In general, concentrations of species with small ranges promoted low levels and concentrations of species with large ranges promoted high levels of compositional similarity. However, patterns documented for exotic species will likely continue to develop, possibly taking on new forms, depending on how geographical distributions and the rate of introductions of exotic species change over time. Our findings also suggest that processes underlying these patterns have operated at two spatiotemporal scales. The first scale reflects historical consequences of anthropogenic activities occurring within regional extents that have promoted the introduction of extralimital natives; the second scale reflects modern consequences of anthropogenic activities operating at an increasingly global extent that have promoted the introduction of exotic species.     

Ecological determinants of the occurrence and dynamics of Vibrio parahaemolyticus in offshore areas

The life cycle of Vibrio parahaemolyticus has been conventionally associated with estuarine areas characterized by moderate salinity and warm seawater temperatures. Recent evidence suggests that the distribution and population dynamics of V. parahaemolyticus may be shaped by the existence of an oceanic transport of communities of this organism mediated by zooplankton. To evaluate this possibility, the presence of V. parahaemolyticus in the water column of offshore areas of Galicia was investigated by PCR monthly over an 18-month period. Analysis of zooplankton and seawater showed that the occurrence of V. parahaemolyticus in offshore areas was almost exclusively associated with zooplankton and was present in 80% of the samples. The influence of environmental factors assessed by generalized additive models revealed that the abundance and seasonality of V. parahaemolyticus in zooplankton was favoured by the concurrence of downwelling periods that promoted the zooplankton patchiness. These results confirm that offshore waters may be common habitats for V. parahaemolyticus, including strains with virulent traits. Additionally, genetically related populations were found in offshore zooplankton and in estuaries dispersed along 1500 km. This finding suggests that zooplankton may operate as a vehicle for oceanic dispersal of V. parahaemolyticus populations, connecting distant regions and habitats, and thereby producing impacts on the local community demography and the spread of Vibrio-related diseases.     

Characteristics and habitats of non-native plant species in the city of Chonju,southern Korea

Investigations on non-native organisms have become an important task of modern ecology throughout the world. The major objective of this study was to identify the characteristics and habitats of non-native plant species in Korean cities in order to derive conclusions on the success of biological invaders. The city of Chonju in southwest Korea was selected as a representative investigation area. All wild-growing vascular plants were recorded in the city on a total of 106 sample plots located in representative land-use types and within various distances of the city center. Frequency, origin, life forms, and plant families of non-native species were analyzed. Additionally, the percentage of non-native species along a gradient from the city center to the outskirts was investigated. We found that most common non-native species of the flora of Chonju are: (i) native to the Northern hemisphere; (ii) belong to the annuals; (iii) belong to the plant families of the Compositae or Leguminosae; and (iv) they perform best on sites that are continuously disturbed by human impact. In conclusion, non-native species play a significant role in enhancing biological diversity in urban areas.     

气候变化对黄土高原及邻近地区稀有种枯蝉分布的潜在影响(英文)

【目的】未来数十年的气候变化预计会是造成很多物种生境丧失的一个重要因素。对适应能力相对脆弱的地方性物种,预测气候变化对其生境的影响将对生物多样性保护具有重要意义。【方法】本文基于最大熵模型,对珍稀蝉科中国特有种枯蝉Subpsaltria yangi在当前和未来气候条件下的生境适宜度进行了评估。【结果】结果表明,枯蝉主要局限分布于黄土高原及邻近地区。预计至2050年,即使在温和的气候变化情景下,枯蝉的生境面积也会明显减少。影响枯蝉栖息地分布的关键因素为年平均气温、最冷月的最低气温、最冷季的平均气温和最潮湿月份的降水量。枯蝉现存种群栖息地应当受到保护,甘肃天水和陕西延安地区应作为枯蝉分布的核心区予以保护,以应对气候变化对其生境带来的影响。【结论】本研究获得的枯蝉适宜生境分布图可以为该稀有物种的新种群发现、现生种群分布地土地规划管理以及有效的自然保护区设立提供重要信息。     

Common species have lower taxonomic diversity Evidence from the urban floras of Brussels and Rome

The species pool hypothesis claims that the large‐scale regional species pool is the chief parameter in determining small‐scale species richness through filtering of species that can persist within a community on the basis of their tolerance of the abiotic environment. Accordingly, different environmental conditions give rise to different species assemblages. From a taxonomic perspective, under the assumption of trait conservatism, co‐occurring species that experience similar environmental conditions are likely to be more taxonomically similar than ecologically distant species. The next step consists in understanding how commonness and rarity of individual species produce the observed taxonomic diversity. In this paper, the importance of environmental filtering in regulating the taxonomic structure of rare and common plant species in the urban floras of Brussels (Belgium) and Rome (Italy) is tested. First, we computed the taxonomic diversity of the rare and common species of Brussels and Rome based on the branching topology of the Linnaean taxonomic trees. Next, using a randomization procedure, we determined whether the taxonomic diversity of the rare species was significantly higher than the diversity of the common species. Results show that, for both urban floras, common species that shape the community matrix and experience similar environmental conditions have a taxonomic diversity that is significantly lower than that of the rare species that represent a relatively incidental set of species of more ‘disperse’ origin. Finally, from a conservation/management perspective our results imply that, given their high taxonomic heterogeneity, the protection of rare species is a central issue for preserving high levels of diversity in urban areas.     

Assessing the vulnerability of riparian vegetation to invasion by Mimulus guttatus: relative importance of biotic and abiotic variables in determining species occurrence and abundance

Riparian habitats are particularly susceptible to invasion by non‐native plants. At present, attempts to build consensus as to what the primary drivers of plant invasion in riparian ecosystems might be is hindered by the absence of common standards for data collected on plant species (e.g. occurrence, or relative abundance). Mimulus guttatus L., a non‐native riparian plant species, was used as a model to determine how environmental drivers influence two aspects of invasibility: species occurrence and abundance (assessed in relation to three variables number of patches, patch area and number of stems per patch). Mimulus occurrence and abundance, together with 20 environmental variables, were surveyed in almost 700 contiguous 50‐m‐long riverbank segments within a catchment in north‐east Scotland. More than half of the segments had been colonized by Mimulus. Occurrence and number of patches responded to similar environmental gradients, particularly bare sediment, boulders, high soil moisture, short‐statured ruderal communities, and open canopies, and tended to be highest downstream where the river was widest. In contrast to occurrence and patch number, patch area and stem number per patch were higher in the upper reaches of the catchment and were positively associated with low tree canopy and vegetation dominated by light‐demanding species and smaller‐statured species. Patch area and stem number per patch were also positively related to grazing. This study has highlighted the importance of assessing more than one measure of invasion success (occurrence or patch number and either patch area or stem number per patch), as they are each determined by a different suite of environmental variables. Abiotic factors, such as sediment availability and presence of boulders, appeared to be the major determinants of occurrence and patch number, whereas biotic factors, such as interspecific competition and grazing, were more important ecological determinants underlying area and stem number per patch.     

The role of light,soil and human factors on the probability of occurrence of an invasive and three native plant species in coastal transitions of coastal Mississippi,USA

Aims Understanding relationships between the distributions of species and their surrounding environment provides a basis for forecasting how species will respond to future environmental changes. In this study, we examined the effects of environmental factors and human developmental features associated with disturbances on probability of occurrence of juveniles of invasive Triadica sebifera and three native plant species, Baccharis halimifolia, Ilex vomitoria and Morella cerifera within a typical coastal transition in coastal Mississippi, USA.Methods We recorded presence of juveniles of focal species and measured environmental factors (soil salinity, canopy openness, soil texture and soil carbon to nitrogen ratio) along an 11.3 km transect located at Grand Bay National Estuarine Research Reserve. Further, we documented anthropogenic features and associated activities as a proxy for human disturbance.Important findings With the exception of I. vomitoria, all other species occurrences were significantly influenced by an interaction between soil salinity and canopy openness. The occurrence of I. vomitoria sharply decreased with salinity. B. halimifolia occurrence peaked at moderate levels of salinity and low to moderate levels of canopy openness. Occurrences of M. cerifera and the invasive T. sebifera were highest at low levels of salinity and canopy openness. These results indicate that salinity is a strong driver that limits distribution of juvenile native and invasive species in coastal transitions. Logistic regression confirmed the positive effects of anthropogenic disturbances on T. sebifera and I. vomitoria occurrence. It appears that while soil salinity is likely to drive retreat of the seaward boundaries of woody plant species distributions, increased human developments along the coast likely enhance the inland spread of species, in particular the invasive T. sebifera by increasing disturbances and facilitating dispersal. Results from this study can offer insight for the development of T. sebifera management and preventive measures for further spread along coastal areas of the southeastern USA.