Beyond the landscape: Resistance modelling infers physical and behavioural gene flow barriers to a mobile carnivore across a metropolitan area

Urbanization affects key aspects of wildlife ecology. Dispersal in urban wildlife species may be impacted by geographical barriers but also by a species’ inherent behavioural variability. There are no functional connectivity analyses using continuous individual‐based sampling across an urban‐rural continuum that would allow a thorough assessment of the relative importance of physical and behavioural dispersal barriers. We used 16 microsatellite loci to genotype 374 red foxes (Vulpes vulpes) from the city of Berlin and surrounding rural regions in Brandenburg in order to study genetic structure and dispersal behaviour of a mobile carnivore across the urban‐rural landscape. We assessed functional connectivity by applying an individual‐based landscape genetic optimization procedure. Three commonly used genetic distance measures yielded different model selection results, with only the results of an eigenvector‐based multivariate analysis reasonably explaining genetic differentiation patterns. Genetic clustering methods and landscape resistance modelling supported the presence of an urban population with reduced dispersal across the city border. Artificial structures (railways, motorways) served as main dispersal corridors within the cityscape, yet urban foxes avoided densely built‐up areas. We show that despite their ubiquitous presence in urban areas, their mobility and behavioural plasticity, foxes were affected in their dispersal by anthropogenic presence. Distinguishing between man‐made structures and sites of human activity, rather than between natural and artificial structures, is thus essential for better understanding urban fox dispersal. This differentiation may also help to understand dispersal of other urban wildlife and to predict how behaviour can shape population genetic structure beyond physical barriers.     

Nests in the cities: adaptive and non-adaptive phenotypic plasticity and convergence in an urban bird

Phenotypic plasticity plays a critical role in adaptation to novel environments. Behavioural plasticity enables more rapid responses to unfamiliar conditions than evolution by natural selection. Urban ecosystems are one such novel environment in which behavioural plasticity has been documented. However, whether such plasticity is adaptive, and if plasticity is convergent among urban populations, is poorly understood. We studied the nesting biology of an ‘urban-adapter’ species, the dark-eyed junco (Junco hyemalis), to understand the role of plasticity in adapting to city life. We examined (i) whether novel nesting behaviours are adaptive, (ii) whether pairs modify nest characteristics in response to prior outcomes, and (iii) whether two urban populations exhibit similar nesting behaviour. We monitored 170 junco nests in urban Los Angeles and compared our results with prior research on 579 nests from urban San Diego. We found that nests placed in ecologically novel locations (off-ground and on artificial surfaces) increased fitness, and that pairs practiced informed re-nesting in site selection. The Los Angeles population more frequently nested off-ground than the San Diego population and exhibited a higher success rate. Our findings suggest that plasticity facilitates adaptation to urban environments, and that the drivers behind novel nesting behaviours are complex and multifaceted.     

珠江口城市段近岸表层水体浮游细菌分离方法比较

为了更好地分离珠江口未/难培养的浮游细菌,本研究以珠江河口三个样点的水体为研究对象,同时采用了纯培养和免培养的方法,对不同培养基的分离效果进行了探索。在纯培养实验中,本研究选择了7种不同的分离培养基,共分离获得153株菌;同时,将扩增子分析结果作为分离效果的参考,所有环境样品中共包含3 553个操作分类单元（operational taxonomic units,OTUs）。对三个样点微生物类群的多样性进行比较,纯培养结果显示珠江口下游珠海样点多样性最高,其次为中大和虎门样点;免培养则显示虎门样点多样性最高;对比7种不同的分离培养基,Z7（R₂A）培养基的分离效果最好,分离菌株数和分离类群的α多样性最高,Z1（改良ISP 2）次之;主坐标分析结合韦恩图的结果表明相比其余的培养基,Z1和Z7培养基分离获得的菌群兼具普遍性和特异性,进一步证明了这两种培养基的分离效果较佳;冗余分析结果表明K₂HPO₄、酵母粉、可溶性淀粉、MgSO₄·7H₂O、麦芽膏和葡萄糖与特定类群的分离有相关关系,其中K₂HPO₄的影响最为显著（P<0.05）。本文通过7种不同培养基对河口微生物分离效果的探究,有助于我们在研究未知微生物的营养特性时,选择成分和组成更合理的培养基来提升河口微生物纯培养的分离效率。     

Application of plant metabarcoding to identify diverse honeybee pollen forage along an urban–agricultural gradient

Understanding animal foraging ecology requires large sample sizes spanning broad environmental and temporal gradients. For pollinators, this has been hampered by the laborious nature of morphologically identifying pollen. Identifying pollen from urban environments is particularly difficult due to the presence of diverse ornamental species associated with consumer horticulture. Metagenetic pollen analysis represents a potential solution to this issue. Building upon prior laboratory and bioinformatic methods, we applied quantitative multilocus metabarcoding to characterize the foraging ecology of honeybee colonies situated in urban, suburban, mixed suburban–agricultural and rural agricultural sites in central Ohio, USA. In cross‐validating a subset of our metabarcoding results using microscopic palynology, we find strong concordance between the molecular and microscopic methods. Our results suggest that forage from the agricultural site exhibited decreased taxonomic diversity and temporal turnover relative to the urban and suburban sites, though the generalization of this observation will require replication across additional sites and cities. Our work demonstrates the power of honeybees as environmental samplers of floral community composition at large spatial scales, aiding in the distinction of taxa characteristically associated with urban or agricultural land use from those distributed ubiquitously across the sampled landscapes. Observed patterns of high forage diversity and compositional turnover in our more urban sites are likely reflective of the fine‐grain heterogeneity and high beta diversity of urban floral landscapes at the scale of honeybee foraging. This provides guidance for future studies investigating how relationships between urbanization and measures of pollinator health are mediated by variation in floral resource dynamics across landscapes.     

The community structure of bird assemblages on urban strangler figs

Figs have been regarded as keystone plant resources that support diverse tropical vertebrate frugivore communities. Planting or conserving large fig trees, such as stranglers, have therefore been proposed for enhancing urban biodiversity. We compared the diversity and community structure of bird assemblages on strangler figs with non‐fig urban trees as well as between the fruiting and non‐fruiting fig trees in an urban setting in Singapore. The total bird abundance across all the fig trees when in fruit was 4.5‐fold higher than on non‐fig trees and 3.5‐fold higher than when the same fig trees were not fruiting, but only attracted two more species. On individual trees, after accounting for the presence of mistletoes, tree height, the area covered by buildings, road lane density, and the distance to natural vegetation, mean diversity was not different between non‐fig trees and fig trees when they were not in fruit. On the other hand, when fruiting, each fig tree on average had 1.4 more species, 3 more counts of non‐native birds, and 1.6 more counts of insectivorous birds than when not fruiting. There was significant compositional turnover between non‐fig trees and non‐fruiting fig trees, while community dispersion was significantly lower among fig trees in fruit. Our results demonstrate that fig trees provide fruit and non‐fruit resources for birds in an urban landscape but do not necessarily support more diverse total bird assemblages than non‐fig trees. Instead, bird communities on fruiting urban figs would be highly homogeneous and dominated by a few species. Abstract in Malay is available with online material.     

“21世纪海上丝绸之路”沿线典型城市气溶胶光学厚度时空分布特征与成因

气溶胶作为悬浮分散在大气中的固态或液态微小颗粒物,对人体健康具有巨大影响,探索区域大气气溶胶变化特征和规律,对监测评估大气环境质量(尤其是人口聚集的城市地区)具有重要意义。本研究以东南亚、南亚和西亚“21世纪海上丝绸之路”沿线9个典型支点城市为例,基于MCD19A2 550 nm AOD产品,结合气象因素、土地利用数据和夜间灯光数据等,探讨亚洲发达城市区域带气溶胶的时空分布、变化特征、影响因素和成因驱动。结果表明: 2013—2018年间,9个城市气溶胶光学厚度(AOD)年平均值从高到低依次为卡拉奇、多哈、吉大港、曼谷、科伦坡、胡志明市、新加坡、瓜达尔和仰光。受区域气候系统和气溶胶类型的影响,各地区年、季和月AOD时序特征差异显著。大多数城市AOD高值区主要分布在城市中心区域或社会经济(如工农业)快速发展的地区。不同气象因素对各地区AOD的影响略有差异:降雨量、相对湿度和风速对东南亚4个城市(胡志明市、曼谷、新加坡和仰光)的影响较大,温度、相对湿度和风速与南亚4个城市(吉大港、科伦坡、卡拉奇和瓜达尔)和西亚多哈的AOD相关性较大。城市区域AOD受社会经济、城市化发展以及气象因素耦合协同作用的综合影响,其中,卡拉奇表现得最显著。     

喀斯特山地城市内山体绿地对城市热岛的减温效应——以安顺市西秀区为例

山体绿地是喀斯特山地城市内典型的城市绿地景观类型,其对于改善城市生态环境、提升喀斯特山地城市生态服务功能具有重要作用。以黔中典型喀斯特山地城市安顺市为研究对象,运用2011年和2016年两期热红外遥感影像和城市景观结构空间数据,在反演分析城市热岛效应及其强度时空分布特征的基础上,运用冷热点分析剖析了山体绿地与城市热岛效应冷点分布区的关系,揭示山体绿地对城市热岛的减温效应。结果表明:基于Landsat热红外遥感数据反演地表温度结果显示,2011—2016年,安顺市西秀区平均反演地表温度升高约4℃;主城区一带热岛效应呈现加剧趋势,但总体热岛面积呈下降趋势,绿岛区多分布于水体和山体绿地中,且山体绿地对热岛效应减缓作用逐年增大;热/冷聚集面积呈现上升趋势,约40%~50%的冷聚集区由山体绿地贡献,热聚集区主要由建筑用地和其他用地构成;500 m格网尺度下,山体绿地面积与地表温度呈显著负相关,表现为山体绿地面积占格网比例每增加10%,地表温度将降低0.17~0.27℃。研究结果可为喀斯特山地城市山体绿地管理、城市绿地空间规划和城市热环境缓解提供科学依据。     

Testing the effect of restoration‐focused silviculture on oak regeneration and groundlayer plant communities in urban–exurban oak woodlands

Throughout their global range, oak‐dominated ecosystems have undergone state changes in stand structure and composition. Land managers face an especially acute challenge in restoring oak ecosystems and promoting oak regeneration in urban–exurban areas, where high‐intensity silvicultural treatments are often not feasible. To investigate low‐intensity management alternatives which could be widely applied in urban–exurban forests, a large‐scale adaptive management experiment was implemented in Lake County, IL, in 2012. Five canopy manipulation treatments of varying intensity, timing, and spatial aggregation were replicated across three study areas and oak seedlings were under‐planted into treatment units following management. Responses of understory light environment, shrub and groundlayer plant communities, and survival and growth of underplanted oak seedlings were evaluated. Understory light availability, canopy openness, total groundlayer plant cover, and groundlayer species diversity all differed among treatments. However, although understory light availability was significantly increased by canopy manipulation, groundlayer communities and oak seedling survival and growth did not differ among treatments. High overall seedling survival rates suggest current conditions are amenable to oak regeneration, but long‐term monitoring will be needed to assess the potential for seedlings to transition to the sapling and canopy layers. Early results demonstrate that canopy‐focused silvicultural treatments can affect the understory light environment and, to some degree, groundlayer plant communities. However, underplanting of oak seedlings paired with subcanopy thinning may be sufficient to restore an oak seedling layer, and (when necessary or preferred) canopy manipulation could potentially be deferred until later in the restoration timeline to promote oak recruitment.     

Reunderstanding Cairo through urban metabolism: Formal versus informal districts resource flow performance in fast urbanizing cities

Urban expansion can be seen as the most pervasive human impact on the environment where its high resource use contributes negatively to climate change and resource scarcity crises. Many experts call for decoupling resource use, economic development, and related urban development especially within cities of the Global South. This paper focuses on investigating resource efficiency through the lens of urban metabolism. It investigates current resource flows, through material flow analysis, from source to sink, in two diverse districts in Cairo: a formal district and an informal one, regarding materials (waste) and mobility. Consequently, the paper discusses locally responsive interventions that address local priorities as opposing to citywide one‐size fits all solution. The paper relies on parcel audits, which are embedded in an Urban Metabolism Information System developed by the Ecocity Builders and their partners, through a joint project with Cairo University. The methodology couples crowd‐sourced data, parcel audits, and experts’ knowledge to better understand resource flows based on a bottom‐up approach, given the unavailability of governmental data on the local level. The paper further correlates the perceived quality of life with the actual resource flows. It utilizes fieldwork investigations to argue against the local misconceptions regarding the inefficiency of informal areas/systems versus the higher efficiency of planned areas/systems. The paper concludes by proposing integrated solutions that respond to local needs and resources. It highlights the challenges and lessons of this tailored bottom‐up approach and its applicability in other cities worldwide.     

Large vertical movements by a goosefish,Lophius americanus,suggests the potential of data storage tags for behavioral studies of benthic fishes

The extensive periodic vertical movements of up to 14 h and 209 m observed in this study for an individual goosefish, Lophius americanus, challenges previous assumptions about the benthic and highly sedentary behavior of the species as well as of other lophiids. Researchers should consider conducting similar data storage tagging studies with other benthic fishes to test assumptions of sedentary behavior.