Temperature‐related shifts in butterfly phenology depend on the habitat

Many species are becoming active earlier in the season as the climate becomes warmer. In parallel to phenological responses to climate change, many species have also been affected by habitat changes due to anthropogenic land use. As habitat type can directly affect microclimatic conditions, concurrent changes in climate and habitat could have interacting effects on the phenology of species. Temperature‐related shifts in phenology, however, have mostly been studied independent of habitat types. Here, I used long‐term data from a highly standardized monitoring program with 519 transects to study how phenology of butterflies is affected by ambient temperature and habitat type. I compared forests, agricultural areas and settlements, reflecting three major land use forms, and considered butterfly species that were observed in all three of these habitats. Seasonal appearance of the butterflies was affected both by the ambient temperature and the habitat type. As expected, warmer temperatures led to an overall advancement of the appearance and flight period of most species. Surprisingly, however, phenology of species was delayed in settlement habitats, even though this habitat type is generally associated with higher temperatures. A possible explanation is dispersal among habitat types, such that source–sink effects affect local phenology. When there is little productivity in settlement areas, observed butterflies may have immigrated from forest or agricultural habitats and thus appear later in settlements. My findings suggest that a spillover of individuals among habitats may affect phenology trends and indicate that phenological studies need to be interpreted in the context of habitat types. This becomes especially important when defining strategies to prevent or mitigate effects of climate and land‐use changes on phenology and abundance of species.     

The learning advantage: bird species that learn their song show a tighter adjustment of song to noisy environments than those that do not learn

Song learning has evolved within several avian groups. Although its evolutionary advantage is not clear, it has been proposed that song learning may be advantageous in allowing birds to adapt their songs to the local acoustic environment. To test this hypothesis, we analysed patterns of song adjustment to noisy environments and explored their possible link to song learning. Bird vocalizations can be masked by low‐frequency noise, and birds respond to this by singing higher‐pitched songs. Most reports of this strategy involve oscines, a group of birds with learning‐based song variability, and it is doubtful whether species that lack song learning (e.g. suboscines) can adjust their songs to noisy environments. We address this question by comparing the degree of song adjustment to noise in a large sample of oscines (17 populations, 14 species) and suboscines (11 populations, 7 species), recorded in Brazil (Manaus, Brasilia and Curitiba) and Mexico City. We found a significantly stronger association between minimum song frequency and noise levels (effect size) in oscines than in suboscines, suggesting a tighter match in oscines between song transmission capacity and ambient acoustics. Suboscines may be more vulnerable to acoustic pollution than oscines and thus less capable of colonizing cities or acoustically novel habitats. Additionally, we found that species whose song frequency was more divergent between populations showed tighter noise–song frequency associations. Our results suggest that song learning and/or song plasticity allows adaptation to new habitats and that this selective advantage may be linked to the evolution of song learning and plasticity.     

Levels,Sources, and Toxic Potential of Polycyclic Aromatic Hydrocarbons in Urban Soil of Delhi,India

This study was done to determine the concentration of PAHs in urban soil of Delhi (India). Surface top soil (up to 10 cm depth) samples were collected from four different sampling sites including industrial, roadside, residential, and agricultural areas of Delhi and 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs) were evaluated. Total PAH concentrations at industrial, roadside, residential, and agricultural sites were 11.46 ± 8.39, 6.96 ± 4.82, 2.12 ± 1.12, and 1.55 ± 1.07 mg/kg (dry weight), respectively, with 3–7 times greater concentrations in industrial and roadside soils than that in residential and agricultural soils. The PAH pattern was dominated by 4- and 5-ring PAHs (contributing >50% to the total PAHs) at industrial and roadside sites with greater concentration of fluoranthene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]anthracene, benzo[ghi]perylene, and pyrene, whereas, residential and agricultural sites showed a predominance of low molecular weight 2- and 3-ring PAHs (fluoranthene, acenaphthene, naphthalene, chrysene, and anthracene). Isomeric pair ratios suggested biomass combustion and fossil fuel emissions as the main sources of PAHs. The toxic equivalency factors (TEFs) showed that carcinogenic potency (benzo[a]pyrene-equivalent concentration (B[a]P_eq) of PAH load in industrial and roadside soils was ～10 and ～6 times greater than the agricultural soil.     

Occurrence and assemblage composition of millipedes (Myriapoda, Diplopoda) and terrestrial isopods (Crustacea, Isopoda, Oniscidea) in urban areas of Switzerland

Terrestrial isopods and millipedes, members of the invertebrate macro-decomposer guild, were collected through pitfall traps in three Swiss cities (Zurich, Lucerne, Lugano). A total of 7,198 individuals of 17 isopod species (7093 ind.), and 10 millipede species (105 ind.) were captured. Besides the Alpine endemic isopod (Trichoniscus alemannicus) and millipede (Cylindroiulus verhoeffi), urban assemblages were mainly composed of widespread, native European and even cosmopolitan species, which are frequent in anthropogenic areas. Overall species richness (isopods and millipedes combined) was similar in Zurich (17 species) and Lucerne (16), while only 13 species were sampled in Lugano. According to the Sørensen index of similarity, species composition of Zurich and Lucerne were more alike, while the one of Lugano was more distinct from the other two cities. This result can be explained by the spatial proximity of Zurich and Lucerne in the north of the Alps compared to Lugano, which is located more distantly and in the south of the Alps. Dominant isopods and millipedes in Zurich and Lucerne were found to be widespread synanthropic species in temperate Europe(Porcellio scaber, Trachelipus rathkii and Ophyiulus pilosus) while the dominant isopod in Lugano (Trachelipus razzautii) is a species with a north-eastern Mediterranean distribution. Our study reveals that the urban millipede and isopod fauna in Swiss cities mainly consists of widespread species, but species of narrower distribution (e.g. Trichoniscus alemannicus, Cylindroiulus verhoeffi) may also find suitable habitats in cities. Despite some signs of biotic homogenization, our study also found compositional differences of millipede and isopod assemblages between northern and southern cities that suggest geographical effects of the regional species pool.     

贵州省城镇建设用地扩展的时空演变特征

选择贵州省的85个城镇为研究区,运用1973年1∶5万地形图,1986、1995、2000和2007年4期高分辨率遥感影像,选取城镇扩展动态度指数、城镇扩展贡献率指数和城镇扩展强度指数3个指标,构建城镇综合扩展程度指数模型,定量分析了1973—2007年4个时期贵州省城镇建设用地扩展的总体特征和时空分异特征。结果表明:从1973—2007年,贵州省城镇建设用地呈持续增长态势,城镇建设用地面积共增加17550.8915hm2,其中2000—2007年贵州省城镇建设用地扩展面积最大,动态度、贡献率和强度指数均最大;研究区建设用地扩展具有明显的空间分异特征,1973—1986年,城镇建设用地扩展主要集中在省会城市贵阳市,1986—1995年,地级城市所在城镇扩展面积和强度快速提高,1995—2000年,交通沿线城镇扩展速度加快,2000—2007年,贵州省城镇扩展强度和综合扩展程度不仅在贵阳市和地级城市较快,而且在区位和自然条件良好的县级城镇也迅速提高。     

北京市麻雀体质水平沿城市化梯度的变化

麻雀是城市和乡村均有分布的鸟类物种.快速的城市化正在使城市麻雀的栖息地和食物资源大量减少.以北京市为例,研究了麻雀的体质水平沿城市化梯度的变化,以期为我国城市化过程中的鸟类保护提供参考.研究结果表明城市高层楼房居民区、低层楼房居民区以及大学校园中麻雀的体质指数显著低于郊区环境,而城市公园和平房居民区麻雀的体质水平则与郊区环境的差异较小.随采样点城市化水平的增加,麻雀的体质水平呈下降趋势,高度城市化的环境导致麻雀的体质水平下降.在城市化过程中,增加城市公园的数量及居民区的植被覆盖量可为麻雀等鸟类提供必要的生活资源,从而实现城市化过程中的生物多样性保护.     

辽宁省城市热岛强度特征及等级划分

根据气象站资料累积时间、资料连续性、站点位置、城郊站间距离、站点数量、迁站情况,对辽宁省61个气象站进行筛选,并利用选出的城郊代表站的月和年气温数据,分析了辽宁省热岛强度的变化范围及幅度,确定了热岛强度等级.结果表明:辽宁省铁岭站、大连站、鞍山站、朝阳站、丹东站、锦州站6个气象站可作为城市气温的代表站,台安站等18个气象站可作为郊区气温的代表站;1980-2009年,辽宁省6个代表城市的热岛强度年变化不同,除铁岭为微弱下降外,其他5市均表现为上升趋势,铁岭年热岛强度较强,大连年热岛强度较弱;6个代表城市的月热岛强度变化也不同,丹东、锦州、铁岭的月热岛强度呈明显的“U”型分布,6市最大热岛强度均出现在1月,最小热岛强度均出现在5-8月,具有冬季强、夏季弱的特点.6市热岛强度的年、月变化范围分别为0.57～2.15℃和-0.70～4.60℃,年和月热岛强度分别有97.8％和72.3％集中在0.5～2.0℃.辽宁省热岛强度可划分为无、弱、强和极强4个等级.     

城市胁迫生境下二球悬铃木叶片的发育稳定度及其环境指示功能

对采自上海市区14个样点的二球悬铃木叶片发育稳定度、叶片气孔密度和气孔长径进行研究。结果表明,在3个采样时期,根据叶片宽度确定的非稳态不对称指数(FA1)和根据叶片侧脉长度确定的偏向性不对称指数(RDA1)在不同环境胁迫程度(UESL)下均表现出显著的差异,但进一步分析表明,各样点FA1与环境胁迫程度UESL之间呈显著的非线性回归关系,而RDA1与环境胁迫程度之间却未显示类似关系。此外,FA1与叶片气孔密度和气孔长径之间的显著相关关系表明,它们可共同作为指示小尺度上环境胁迫的有效指标,而RDA1是叶片的一种正常发育状态参数,并不适于反映环境胁迫状态。     

Environmental and vegetation variables have a greater influence than habitat fragmentation in structuring lizard communities in remnant urban bushland

Abstract The expansion of urban areas and adjacent farming land into natural landscapes modifies habitats and produces small isolated pockets of native vegetation. This fragmentation of the natural habitat subdivides animal communities, reduces population sizes and increases vulnerability to extinction. In this paper we investigate whether fragmentation decreases lizard species richness, composition, overall abundance and abundance at the species level. Urban remnants consisting of five small (< 10 ha) and four large (> 10 ha) fragments of natural bushland were paired with continuous bushland areas located near Hobart, Tasmania, Australia. These remnants were surveyed six times, using pitfall traps, from November 2001 to March 2002. Lizard species richness and abundance were not significantly influenced by habitat fragmentation or fragment size. Egernia whitii was the only lizard species significantly influenced by fragment size, and was only present in large fragments and continuous bush. Vegetation type and structure as well as environmental variables (geology and aspect) influenced the structure of reptile communities. Lizard species that were able to use a number of different habitat types were found to persist at most sites, irrespective of fragment size. Edge environment did not significantly influence lizard species richness or abundance in remnant areas. Lizard species richness was significantly lower in sites that had a high ratio of exotic to native plant species. Therefore, if remnants continue to be invaded by exotic plants, lizard species that require native plant communities will become increasingly vulnerable to local extinction. Our results suggest that lizard species requiring specialized habitats, such as E. whitii, may persist in large urban remnants rather than small urban remnants because large reserves are more likely to encompass rare habitats, such as rocky outcrops. Habitat heterogeneity, rather than size, may be the key to their persistence.     

中国城市森林的特点及发展思考

城市森林作为一种与城市密切相关的森林类型 ,受人为干扰的影响很大 ,承受的大气污染、土壤污染、水污染等环境压力大 ,无论是在组成上还是在功能上 ,都表现出不同于一般森林类型的特点。本文在论述了我国发展城市森林意义的基础上 ,分析了城市森林功能、结构、生长、生物多样性、管护要求、效益等方面具有的特殊性 ,并对我国城市森林发展的一些原则性问题进行了探讨 ,以期对正在兴起的我国城市森林的发展提供帮助