Spatial and temporal habitat partitioning by calliphorid blowflies

Calliphorid blowflies perform an essential ecosystem service in the consumption, recycling and dispersion of carrion nutrients and are considered amongst the most important functional groups in an ecosystem. Some species are of economic importance as facultative agents of livestock myiasis. The interspecific ecological differences that facilitate coexistence within the blowfly community are not fully understood. The aim of this work was to quantify differences in habitat use by calliphorid species. Thirty traps were distributed among three habitats at two sites in southwest England for collections made during March–August 2016. A total of 17 246 specimens were caught, of which 2427 were Lucilia sericata, 51 Lucilia richardsi, 6580 Lucilia caesar, 307 Lucilia ampullacea, 4881 Calliphora vicina and 2959 Calliphora vomitoria (all: Diptera: Calliphoridae). Lucilia sericata was the dominant species in open habitats, whereas L. caesar was the most abundant species in shaded habitats. Calliphora specimens were more abundant in the cooler months. These findings suggest that Calliphora and Lucilia species show strong temporal segregation mediated by temperature, and that species of the genus Lucilia show differences in the use of habitats that are likely to be driven by differences in humidity tolerance and light intensity. These factors in combination result in effective niche partitioning.     

Simulated climate change: are passive greenhouses a valid microcosm for testing the biological effects of environmental perturbations?

This paper considers the use of passive greenhouse apparatus in field experiments investigating the biological consequences of climate change. The literature contains many accounts of such experiments claiming relevance of greenhouse treatment effects to global change scenarios. However, inadequacies in microclimate monitoring, together with incomplete understanding of greenhouse modes of action, cast doubt upon such claims. Here, treatment effects upon temperature (magnitude, range, variation, rates of change), moisture (humidity, precipitation, soil water content), light (intensity, spectral distribution), gas composition, snow cover, and wind speed are reviewed in the context of Intergovernmental Panel on Climate Change (IPCC) predictions. It is revealed that greenhouses modify each of these potentially limiting factors in a complex and interactive manner, but that the relationship between this modification and forecast conditions of climate change is poor. Interpretation of biological responses, and their extrapolation to predictive models, is thus unreliable. In order that future greenhouse experiments may overcome criticisms of artefact and lack of rigour, two amendments to methodology are proposed: (1) objective-orientated design of greenhouse apparatus (2) multiple controls addressing individual environmental factors. The importance of a priori testing of microclimate treatment effects is stressed.     

A simple,band‐mounted device to measure behaviorally modified thermal microclimates experienced by birds

Birds encounter climate at the scale of microclimates that can vary rapidly in time and space and so understanding potential vulnerability and adaptations to those microclimates requires fine‐scale measurements that accurately track thermal exposures. However, few options exist for recording the microclimates actually experienced by birds (realized microclimates). We constructed and tested a simple, low‐cost, temperature logger for recording the realized microclimates of ground‐nesting birds. We developed attachment protocols for band‐mounting Thermochron iButtons on Ring‐billed Gull (Larus delawarensis) chicks. We tested these mounted, temperature‐logging devices on 20 chicks weighing > 200 g (device weight was 4 g), attaching devices for 48 h and observing behavior before and after attachment and removal. Devices recorded temperature immediately surrounding the leg at 2‐min intervals. Recorded temperatures were strong predictors of observed thermoregulatory behaviors (panting and sitting), outperforming predictions based on air temperatures measured by basic, static approaches. Through comparison with matched controls (chicks with just a band), we detected no adverse physiological effects of devices, no effects on social or feeding behavior, and only a short‐term decrease in inactivity immediately after device attachment (likely due to increased preening). By attaching iButtons to the legs of birds, we quantified realized thermal exposure, integrating air temperature, modes of environmental heat transfer, and bird behavior at microclimatic scales. Although not yet validated for broader use, our approach (including possible miniaturization) should be suitable to measure thermal exposure of adults, not just chicks, allowing collection of data concerning thermal exposures during flight under field conditions. At ~ $25 USD per device, our approach facilitates experimental protocols with robust sample sizes, even for relatively modest budgets.     

Butterfly Response to Microclimatic Conditions Following Ponderosa Pine Restoration

Efforts to restore ponderosa pine ecosystems to open, park‐like conditions that predominated prior to European‐American settlement result in altered stand structure and increased landscape heterogeneity, potentially altering habitat suitability for invertebrates and other forest organisms. We examined the responses of two butterfly species, Colias eurytheme and Neophasia menapia, to microclimatic changes at structural edges created by experimental restoration treatments in northern Arizona. We monitored microclimate, including air temperature, light intensity, and vapor pressure deficit (VPD), on several mornings during butterfly releases. We placed adult butterflies at east‐ and west‐facing edges approximately one half‐hour before dawn to determine their behavioral response to microclimatic differences between east‐ and west‐facing edges. After sunrise, all three microclimatic variables were higher at east‐facing edges, and the difference in microclimate between the two edge orientations increased through early morning. For both species, butterflies placed at east‐facing edges flew earlier than butterflies at west‐facing edges. Colias eurytheme, an open‐habitat species, tended to move toward the treated forest during initial flight, while movements of Neophasia menapia, a forest‐dwelling species, did not differ from random flight. Our results indicate that butterflies respond to microclimatic factors associated with restoration treatments, while responses to structural changes in habitat vary among species, based on habitat and food plant preferences. These changes in forest structure and microclimate may affect the distribution of many mobile invertebrates in forested landscapes undergoing restoration treatments.     

Epiphyte Biomass and Canopy Microclimate in the Tropical Lowland Cloud Forest of French Guiana

Recent work on bryophyte diversity in lowland forests of northern South America has suggested the existence of a new type of cloud forest, the ‘tropical lowland cloud forest’ (LCF). LCF occurs in river valleys in hilly areas with high air humidity and morning fog, and is rich in epiphytes. We explored epiphyte abundance and canopy microclimate of LCF in a lowland area (200–400 m asl) near Saül, central French Guiana. We analyzed the vertical distribution of epiphytic cover and biomass on 48 trees, in LCF and in lowland rain forest (LRF) without fog. Trees in LCF had significantly more epiphytic biomass than in LRF; mean total epiphytic biomass in LCF was about 59 g/m², and 35 g/m² in LRF. In all height zones on the trees, total epiphyte cover in LCF exceeded that in LRF, with ca 70 percent mean cover in LCF and ca 15 percent in LRF. During both wet and dry seasons, mean diurnal relative air humidity (RH) was higher in LCF than in LRF, and persistence of high RH after sunrise significantly longer in LCF. We suggest that the prolonged availability of high air humidity in LCF and the additional input of liquid water through fog, enhance epiphyte growth in LCF by shortening the desiccation period and lengthening the period of photosynthetic activity of the plants.     

上海南京东路热舒适分析与评价

为探析夏热冬冷地区城市街道的空间因子对小气候与人体热舒适的影响及相互作用规律,通过对上海南京东路步行街中典型的风景园林空间按顶面遮蔽方式分为4种空间类型下的12个测点进行冬夏两季小气候实测及热舒适问卷调查,分析不同顶面遮蔽对风景园林小气候风湿热的影响差异,并结合热舒适评价指标的计算和使用者热舒适问卷,评价不同顶面遮蔽空间下人体热舒适感受。结果显示：1）根据热舒适问卷,建筑遮蔽区位于街道北侧的悬挑区在冬季最舒适,夏季最舒适的是树荫全遮蔽区;2）通过改善空间遮蔽程度与类型,根据风向与距街道十字交叉口的距离合理进行街道设计可以对街道中的太阳辐射与风环境产生显著影响,从而改善街道热舒适;3）采用生理等效温度（PET）指标计算的热中性范围冬季是16.90~28.95℃,夏季是9.05~22.57℃;4）PET评价在高温季节低估了风速对热舒适的影响,提出了基于问卷的热舒适预测方程。可为未来城市街道的舒适性规划建设提供经验与参考。     

小麦与蚕豆间作系统施氮对蚕豆赤斑病发生和冠层微气候的影响

通过田间小区试验,设N₀(0 kg·hm^-2)、N₁(45 kg·hm^-2)、N₂(90 kg·hm^-2)、N₃(135 kg·hm^-2)4个施氮水平,研究不同施氮水平下小麦与蚕豆间作对蚕豆赤斑病发生和冠层微气候的影响,探讨间作系统氮肥调控下冠层微气候变化及其与蚕豆赤斑病发生的关系.结果表明: 施氮提高了蚕豆单、间作种植模式下蚕豆赤斑病发病盛期的病情指数,增幅27.2%～58.0%,增加了病情进展曲线下面积(AUDPC),增幅15.0%～101.8%,N₃水平下赤斑病病情指数和AUDPC最高.施氮使蚕豆冠层温度降低0.2～1.1 ℃,冠层透光率降低1.7%～29.7%,冠层相对湿度增加0.5%～28.7%.与单作相比,间作蚕豆赤斑病病情指数显著降低36.3%～48.1%,AUDPC显著降低44.0%～53.6%,冠层温度和透光率分别提高2.1%～8.7%和12.0%～53.8%,相对湿度降低11.6%～31.6%.相关分析表明,冠层温度和透光率与赤斑病病情指数呈显著负相关,而湿度与病情指数呈显著正相关.表明高氮恶化了冠层微气候环境,加重了蚕豆赤斑病的发生和危害,而间作对蚕豆冠层微气候的改善是控制蚕豆赤斑病发展的重要原因.     

深畦栽培对干旱胁迫下葡萄叶幕微气候和光合作用的影响

试验以‘京亚’和‘红地球’葡萄品种2年生苗木为材料,在田间遮雨棚内考察了自然干旱胁迫下深畦栽植和平畦栽植葡萄根际土壤湿度、叶幕微气候因子、光合作用参数变化特征,探讨根际土壤湿度与叶幕气候互作对葡萄光合作用的影响。结果显示:(1)在干旱逆境下,葡萄根际土壤湿度和叶幕微气候因子交互作用能通过影响水分条件来影响葡萄的光合作用;土壤湿度阀值是葡萄进行光合作用时水分利用最有效的土壤湿度点值,土壤湿度阀值存在“阀值漂移”现象,与叶幕空气湿度呈明显负相关关系,维持较高的叶幕空气湿度有利于实现在较低的土壤湿度下达到更高的光合效率。(2)在干旱逆境下,与平畦栽植相比,深畦栽植在改善葡萄根际土壤水分和叶幕微气候方面具有明显的优势,在该模式下葡萄具有更强的保水能力和更高的水分利用效率,从而具有更强的光合效率。(3)采用深畦栽植模式时,根际土壤相对含水量30%~50%是显著影响葡萄光合作用的土壤湿度区间;根际土壤相对含水量分别在43.32%~50.00%和40.19%~50.00%是‘京亚’和‘红地球’光合作用适宜的土壤湿度范围,在43.32%和40.19%时分别为2种葡萄光合作用水分利用效率达到最高的最适土壤湿度。研究发现,干旱逆境条件下,葡萄根际土壤湿度和叶幕微气候因子交互作用能改善葡萄的光合作用效率;深畦栽植葡萄光合作用对土壤湿度的需求较低,在相对较低的土壤湿度即可达到相对较高的光合能力;深畦栽植模式可以协调葡萄光合作用和水分消耗之间的关系,具有较高的水分利用效率和光合能力,是干旱地区进行葡萄抗旱节水生产的理想模式。