Impact of bull age, sperm processing, and microclimatic conditions on the viability and DNA integrity of cryopreserved bovine sperm.

Context Seasonal microclimatic fluctuations can cause changes in sperm quality even in dairy bulls bred under temperate climate. These changes can vary between sires of different age and affect sperm freezability. Aims We aimed to evaluate the modulating effect of bull age and equilibration time before freezing on the seasonal pattern of sperm viability and DNA integrity post-thaw. Methods In the frame of systematic sperm quality control, we assessed the integrity of sperm plasma membrane and acrosome (PMAI) in 15,496 cryopreserved bovine batches, and the percentage of sperm with high DNA fragmentation index (%DFI) after 0h and 3h incubation at 38°C post-thaw (3h) in 3422 batches. Semen was equilibrated for 24h before freezing if collected on Monday or Wednesday and 72h if produced on Friday. We investigated the effect of season, bull age, equilibration, and temperature-humidity index (THI) on the day of semen collection on sperm traits using mixed-effects linear models. Key results PMAI and %DFI (0h and 3h) deteriorated with increasing THI. The effect of THI on %DFI was detected with a 30-day time lag. Seasonal fluctuations of sperm quality were similar between young, mature, and older sires. Prolonged equilibration did not affect PMAI but was linked to elevated %DFI (3h) in summer. Conclusions Extending equilibration from 24 to 72h is compatible with commercial standards of bovine sperm quality post-thaw; however, it could interfere with the seasonal pattern of the latter. Implications Systematic monitoring of bovine sperm quality enables the prompt detection of stress factors related to microclimate and semen processing.

Dynamics and drivers of mycorrhizal fungi after glacier retreat.

The development of terrestrial ecosystems depends greatly on plant mutualists such as mycorrhizal fungi. The global retreat of glaciers exposes nutrient-poor substrates in extreme environments and provides a unique opportunity to study early successions of mycorrhizal fungi by assessing their dynamics and drivers. We combined environmental DNA metabarcoding and measurements of local conditions to assess the succession of mycorrhizal communities during soil development in 46 glacier forelands around the globe, testing whether dynamics and drivers differ between mycorrhizal types. Mycorrhizal fungi colonized deglaciated areas very quickly (< 10 yr), with arbuscular mycorrhizal fungi tending to become more diverse through time compared to ectomycorrhizal fungi. Both alpha- and beta-diversity of arbuscular mycorrhizal fungi were significantly related to time since glacier retreat and plant communities, while microclimate and primary productivity were more important for ectomycorrhizal fungi. The richness and composition of mycorrhizal communities were also significantly explained by soil chemistry, highlighting the importance of microhabitat for community dynamics. The acceleration of ice melt and the modifications of microclimate forecasted by climate change scenarios are expected to impact the diversity of mycorrhizal partners. These changes could alter the interactions underlying biotic colonization and belowground-aboveground linkages, with multifaceted impacts on soil development and associated ecological processes.

Vineyard microclimate alterations induced by black inter-row mulch through transcriptome reshaped the flavoromics of cabernet sauvignon grapes.

BACKGROUND: Weed control is essential for agricultural floor management in vineyards and the inter-row mulching is an eco-friendly practice to inhibit weed growth via filtering out photosynthetically active radiation. Besides weed suppression, inter-row mulching can influence grapevine growth and the accumulation of metabolites in grape berries. However, the complex interaction of multiple factors in the field challenges the understanding of molecular mechanisms on the regulated metabolites. In the current study, black geotextile inter-row mulch (M) was applied for two vintages (2016-2017) from anthesis to harvest. Metabolomics and transcriptomics analysis were conducted in two vintages, aiming to provide insights into metabolic and molecular responses of Cabernet Sauvignon grapes to M in a semi-arid climate. RESULTS: Upregulation of genes related to photosynthesis and heat shock proteins confirmed that M weakened the total light exposure and grapes suffered heat stress, resulting in lower sugar-acid ratio at harvest. Key genes responsible for enhancements in phenylalanine, glutamine, ornithine, arginine, and C6 alcohol concentrations, and the downward trend in ε-viniferin, anthocyanins, flavonols, terpenes, and norisoprenoids in M grapes were identified. In addition, several modules significantly correlated with the metabolic biomarkers through weighted correlation network analysis, and the potential key transcription factors regulating the above metabolites including VviGATA11, VviHSFA6B, and VviWRKY03 were also identified. CONCLUSION: This study provides a valuable overview of metabolic and transcriptomic responses of M grapes in semi-arid climates, which could facilitate understanding the complex regulatory network of metabolites in response to microclimate changes.

The role of environmental gradients and microclimates in structuring communities and functional groups of lizards in a rainforest-savanna transition area.

Environmental heterogeneity poses a significant influence on the functional characteristics of species and communities at local scales. Environmental transition zones, such as at the savanna-forest borders, can act as regions of ecological tension when subjected to sharp variations in the microclimate. For ectothermic organisms, such as lizards, environmental temperatures directly influence physiological capabilities, and some species use different thermoregulation strategies that produce varied responses to local climatic conditions, which in turn affect species occurrence and community dynamics. In the context of global warming, these various strategies confer different types of vulnerability as well as risks of extinction. To assess the vulnerability of a species and understand the relationships between environmental variations, thermal tolerance of a species and community structure, lizard communities in forest-savanna transition areas of two national parks in the southwestern Amazon were sampled and their thermal functional traits were characterized. Then, we investigated how community structure and functional thermal variation were shaped by two environmental predictors (i.e., microclimates estimated locally and vegetation structure estimated from remote sensing). It was found that the community structure was more strongly predicted by the canopy surface reflectance values obtained via remote sensing than by microclimate variables. Environmental temperatures were not the most important factor affecting the occurrence of species, and the variations in ecothermal traits demonstrated a pattern within the taxonomic hierarchy at the family level. This pattern may indicate a tendency for evolutionary history to indirectly influence these functional features. Considering the estimates of the thermal tolerance range and warming tolerance, thermoconformer lizards are likely to be more vulnerable and at greater risk of extinction due to global warming than thermoregulators. The latter, more associated with open environments, seem to take advantage of their lower vulnerability and occur in both habitat types across the transition, potentially out-competing and further increasing the risk of extinction and vulnerability of forest-adapted thermoconformer lizards in these transitional areas.

Physiological and behavioural adaptations by big brown bats hibernating in dry rock crevices.

Winter energy stores are finite and factors influencing patterns of activity are important for overwintering energetics and survival. Hibernation patterns (e.g., torpor bout duration and arousal frequency) often depend on microclimate, with more stable hibernacula associated with greater energy savings than less stable hibernacula. We monitored hibernation patterns of individual big brown bats (Eptesicus fuscus; Palisot de Beauvois, 1796) overwintering in rock-crevices that are smaller, drier, and less thermally stable than most known cave hibernacula. While such conditions would be predicted to increase arousal frequency in many hibernators, we did not find support for this. We found that bats were insensitive to changes in hibernacula microclimate (temperature and humidity) while torpid. We also found that the probability of arousal from torpor remained under circadian influence, likely because throughout the winter during arousals, bats commonly exit their hibernacula. We calculated that individuals spend most of their energy on maintaining a torpid body temperature a few degrees above the range of ambient temperatures during steady-state torpor, rather than during arousals as is typical of other small mammalian hibernators. Flight appears to be an important winter activity that may expedite the benefits of euthermic periods and allow for short, physiologically effective arousals. Overall, we found that big brown bats in rock crevices exhibit different hibernation patterns than conspecifics hibernating in buildings and caves.

Spatiotemporal assessment of the nexus between urban sprawl and land surface temperature as microclimatic effect: implications for urban planning.

Rapid urbanisation has led to significant environmental and climatic changes worldwide, especially in urban heat islands where increased land surface temperature (LST) poses a major challenge to sustainable urban living. In the city of Abha in southwestern Saudi Arabia, a region experiencing rapid urban growth, the impact of such expansion on LST and the resulting microclimatic changes are still poorly understood. This study aims to explore the dynamics of urban sprawl and its direct impact on LST to provide important insights for urban planning and climate change mitigation strategies. Using the random forest (RF) algorithm optimised for land use and land cover (LULC) mapping, LULC models were derived that had an overall accuracy of 87.70%, 86.27% and 93.53% for 1990, 2000 and 2020, respectively. The mono-window algorithm facilitated the derivation of LST, while Markovian transition matrices and spatial linear regression models assessed LULC dynamics and LST trends. Notably, built-up areas grew from 69.40 km2 in 1990 to 338.74 km2 in 2020, while LST in urban areas showed a pronounced warming trend, with temperatures increasing from an average of 43.71 °C in 1990 to 50.46 °C in 2020. Six landscape fragmentation indices were then calculated for urban areas over three decades. The results show that the Largest Patch Index (LPI) increases from 22.78 in 1990 to 65.24 in 2020, and the number of patches (NP) escalates from 2,531 in 1990 to an impressive 10,710 in 2020. Further regression analyses highlighted the morphological changes in the cities and attributed almost 97% of the LST variability to these urban patch dynamics. In addition, water bodies showed a cooling trend with a temperature decrease from 33.76 °C in 2000 to 29.69 °C in 2020, suggesting an anthropogenic influence. The conclusion emphasises the urgent need for sustainable urban planning to counteract the warming trends associated with urban sprawl and promote climate resilience.

The effects of different landscape strategies on outdoor thermal comfort in village squares: a case study in Dayuwan village in Wuhan City.

Appropriate landscape configurations significantly mitigate rural thermal degradation. However, limited research exists on seasonal thermal comfort and the interconnections among landscape elements. Using ENVI-met software and field measurements, this study analyzed the microclimate of Dayuwan Village Square in Wuhan City. Fifteen design scenarios, including tree planting, building greening, albedo adjustment, and expanded tree coverage, were quantitatively evaluated to assess their impact on outdoor thermal comfort. Additionally, synergistic interactions between mitigation strategies were explored. The study found that increasing evergreen tree coverage by 50% has minimal impact on comfort during winter and spring. However, it significantly reduces temperatures in summer and autumn, resulting in average predicted mean vote (PMV) decreases of 0.315 and 0.643, respectively. Additionally, this strategy optimizes PMV values at 18:00 on extreme days, with a 0.102 decrease in summer and a 0.002 increase in winter. This research offers practical and sustainable guidance to designers for enhancing mitigation effects through optimal landscape configuration, providing a technical framework for rural environmental improvements.

Heel skin microclimate control: Secondary analysis of a self-controlled randomized clinical trial.

OBJECTIVE: this study was undertaken to evaluate the efficacy of multilayer polyurethane foam with silicone (MPF) compared to transparent polyurethane film (TPF) dressings in the control of heel skin microclimate (temperature and moisture) of hospitalized patients undergoing elective surgeries. METHOD: the study took of a secondary analysis of a randomized self-controlled trial, involving patients undergoing elective surgical procedure of cardiac and gastrointestinal specialties in a university hospital in southern Brazil, from March 2019 to February 2020. Patients served as their own control, with their heels randomly allocated to either TPF (control) or MPF (intervention). Skin temperature was measured using a digital infrared thermometer; and moisture determined through capacitance, at the beginning and end of surgery. The study was registered in the Brazilian Registry of Clinical Trials: RBR-5GKNG5. RESULTS: significant difference in the microclimate variables were observed when the groups (intervention and control) and the timepoint of measurement (beginning and end of surgery) were compared. When assessing temperature, an increase (+3.3 °C) was observed with TPF and a decrease (-7.4 °C) was recorded with MPF. Regarding skin moisture, an increase in moisture (+14.6 AU) was recorded with TPF and a slight decrease (-0.3 AU) with MPF. CONCLUSIONS: The findings of this study suggest that MPF is more effective than TPF in controlling skin microclimate (temperature and moisture) in heels skin of hospitalized patients undergoing elective surgeries. However, this control should be better investigated in other studies.

Effects of street tree configuration and placement on roadside thermal environment within a tropical urban canyon.

The Urban Heat Island (UHI) effect increases surface and air temperatures, affecting urban health and well-being. A well-known UHI mitigation measure is the increased roadside tree vegetation facilitating evapotranspiration and shade. In its implementation, the identification of thermally optimal street tree configurations and a quantitative assessment of how various street tree configurations impact the roadside thermal environment were deemed essential and were chosen as the main aims of the study. Twelve tropical urban canyons were categorized into three clusters representative of different street tree placement and configuration scenarios. A control cluster devoid of any roadside trees was also selected. The CFD-based 3-D microclimate model 'ENVI-met' was used to identify suitable roadside urban tree planting scenarios for better microclimate regulation. From a tree planting scenario analysis done as part of the study, the greening scenario of using a 'Continuous tree row (Densely foliated - high Leaf Area Density - LAD)' tree configuration was recognized with the highest ambient temperature reduction of 1.41 °C. The study outcomes reveal that tree configuration of high LAD street trees placed in closer spacing contributes towards the better cooling effect of roadside environments and thus improves thermal comfort for warmer tropical climates of higher humidity levels. The study's findings offer valuable insights for urban planning professionals and policymakers involved in designing future cities and urban developments. They emphasize the importance of strategic tree-planting designs and configurations to enhance thermal comfort and livability in urban areas. This highlights the need to avoid ad-hoc procedures and instead prioritize well-planned roadside tree configurations within urban canyons.

Landscape level associations between birds, mosquitoes and microclimates: possible consequences for disease transmission?

BACKGROUND: Mosquito-borne diseases are on the rise. While climatic factors have been linked to disease occurrences, they do not explain the non-random spatial distribution in disease outbreaks. Landscape-related factors, such as vegetation structure, likely play a crucial but hitherto unquantified role. METHODS: We explored how three critically important factors that are associated with mosquito-borne disease outbreaks: microclimate, mosquito abundance and bird communities, vary at the landscape scale. We compared the co-occurrence of these three factors in two contrasting habitat types (forest versus grassland) across five rural locations in the central part of the Netherlands between June and September 2021. RESULTS: Our results show that forest patches provide a more sheltered microclimate, and a higher overall abundance of birds. When accounting for differences in landscape characteristics, we also observed that the number of mosquitoes was higher in isolated forest patches. CONCLUSIONS: Our findings indicate that, at the landscape scale, variation in tree cover coincides with suitable microclimate and high Culex pipiens and bird abundance. Overall, these factors can help understand the non-random spatial distribution of mosquito-borne disease outbreaks.

Microclimate modulation: An overlooked mechanism influencing the impact of plant diversity on ecosystem functioning.

Changes in climate and biodiversity are widely recognized as primary global change drivers of ecosystem structure and functioning, also affecting ecosystem services provided to human populations. Increasing plant diversity not only enhances ecosystem functioning and stability but also mitigates climate change effects and buffers extreme weather conditions, yet the underlying mechanisms remain largely unclear. Recent studies have shown that plant diversity can mitigate climate change (e.g. reduce temperature fluctuations or drought through microclimatic effects) in different compartments of the focal ecosystem, which as such may contribute to the effect of plant diversity on ecosystem properties and functioning. However, these potential plant diversity-induced microclimate effects are not sufficiently understood. Here, we explored the consequences of climate modulation through microclimate modification by plant diversity for ecosystem functioning as a potential mechanism contributing to the widely documented biodiversity-ecosystem functioning (BEF) relationships, using a combination of theoretical and simulation approaches. We focused on a diverse set of response variables at various levels of integration ranging from ecosystem-level carbon exchange to soil enzyme activity, including population dynamics and the activity of specific organisms. Here, we demonstrated that a vegetation layer composed of many plant species has the potential to influence ecosystem functioning and stability through the modification of microclimatic conditions, thus mitigating the negative impacts of climate extremes on ecosystem functioning. Integrating microclimatic processes (e.g. temperature, humidity and light modulation) as a mechanism contributing to the BEF relationships is a promising avenue to improve our understanding of the effects of climate change on ecosystem functioning and to better predict future ecosystem structure, functioning and services. In addition, microclimate management and monitoring should be seen as a potential tool by practitioners to adapt ecosystems to climate change.

Topography influences diurnal and seasonal microclimate fluctuations in hilly terrain environments of coastal California.

Understanding the topographic basis for microclimatic variation remains fundamental to predicting the site level effects of warming air temperatures. Quantifying diurnal fluctuation and seasonal extremes in relation to topography offers insight into the potential relationship between site level conditions and changes in regional climate. The present study investigated an annual understory temperature regime for 50 sites distributed across a topographically diverse area (>12 km2) comprised of mixed evergreen-deciduous woodland vegetation typical of California coastal ranges. We investigated the effect of topography and tree cover on site-to-site variation in near-surface temperatures using a combination of multiple linear regression and multivariate techniques. Sites in topographically depressed areas (e.g., valley bottoms) exhibited larger seasonal and diurnal variation. Elevation (at 10 m resolution) was found to be the primary driver of daily and seasonal variations, in addition to hillslope position, canopy cover and northness. The elevation effect on seasonal mean temperatures was inverted, reflecting large-scale cold-air pooling in the study region, with elevated minimum and mean temperature at higher elevations. Additionally, several of our sites showed considerable buffering (dampened diurnal and seasonal temperature fluctuations) compared to average regional conditions measured at an on-site weather station. Results from this study help inform efforts to extrapolate temperature records across large landscapes and have the potential to improve our ecological understanding of fine-scale seasonal climate variation in coastal range environments.

Cascading impacts of overstory structure in managed forests on understory structure, microclimate conditions, and Ixodes scapularis (Acari: Ixodidae) densities.

Forest management practices designed to meet varied landowner objectives affect wildlife habitat and may interrupt the life-cycle stages of disease vectors, including the black-legged tick, Ixodes scapularis Say (Acari: Ixodidae). Ixodes scapularis transmits multiple pathogens including Borrelia burgdorferi, the causative agent of Lyme disease, which is the most common tick-borne disease in the United States. There is evidence that a range of active forest management practices (e.g., invasive plant removal, prescribed burning) can alter tick densities and pathogen transmission. However, few studies have investigated relationships between forest stand structural variables commonly manipulated by timber harvesting and tick ecology. Foresters may harvest timber to create certain forest structural conditions like the mean number of trees, or basal area, per hectare. This study used a spatially replicated experiment in a blocked design to compare forest stands with a range of overstory structures and document variations in the midstory, understory, and forest floor, as well as microclimate conditions within tick off-host habitat. Greater numbers of trees or basal area per hectare correlated with greater canopy closure but less understory cover, stabilized microclimate temperature, higher microclimate humidity, and greater I. scapularis nymph densities. A random forest model identified understory forest structure as the strongest predictor of nymph densities. There was no relationship between the number of trees or basal area per hectare and daily deer (Odocoileus virginianus Zimmermann) activity or nymphal infection prevalence. These findings provide a deeper understanding of tick-habitat associations within a forest stand and have the potential to inform forest management decisions.

Sensing the dependable surficial signatures of temporal groundwater variations in arid coastal regions through geospatial techniques with respect to microclimate changes.

Reports on Groundwater level variations and quality changes have been a critical issue, especially in arid regions. An attempt has been made in this study to determine the surface manifestations of groundwater variations through processing imageries for determining the changes in land use, Normalized Differential Building Index (NDBI), Normalized Difference Vegetation Index (NDVI), Land Surface Temperature (LST), along with Groundwater level (GWL) and Electrical conductivity (EC). Decadal variation between these parameters for 2013 and 2023 shows that the average water level had increased by 1.03amsl, while the EC values of groundwater decreased by 418 µS/cm. The decrease in EC values indicates freshwater recharge, promoting natural vegetation, thus reducing the LST values by 3.28 °C. In addition, urban landscaping and relatively lesser emissivity from built-up surfaces than the sandy desert have further reduced the LST. The interrelationship of the parameters indicates that an increase in LST correlates with an increase in NDBI and with less significant changes in NDVI. The lowering of the LST along the coastal regions was inferred to be due to the influence of Sea breeze, adjacent moisture from the ocean, shallow water level, and the shadow effect of the buildings. Further, the increase in water level was mainly attributed to the recent increase in rainfall and the extreme event in 2018. The higher EC in the lesser NDBI regions is attributed to the anthropogenic contamination from agriculture and landfill leachates. Though there was an increase in NDBI, the LST of the region was inferred to be reduced mainly due to the increase in water level and reduction of emission from desert sand by recent urban developments.

Study of summer microclimate and PM2.5 concentration in campus plant communities.

Understanding the influencing effect of meteorological factors and air pollutants in the campus plot and the relationship between them is an important topic in the planning and design of campus green space. The changes of pollutant concentrations and meteorological factors in campus green space have certain patterns and specific influencing factors. In this study, we selected four sample plots in Nanjing Forestry University as the research objects, and collected various environmental parameters of the four plots on July 25, 2022. The results showed that the main influences of meteorological factors are the type of the underlying surface of the site, the degree of plant canopy density and the shade coverage area of the building. These factors mainly have a great influence on the value of temperature and humidity. The comprehensive influencing factors can be concluded that the cooling and humidifying effect of the site is ranked as follows: forest > lawn > asphalt road > concrete Square. The main influencing factors of pollutants are: illumination, wind speed, temperature and relative humidity. Among them, illumination and temperature have a negative correlation with PM2.5, wind speed and relative humidity have a positive correlation with PM2.5. Our research shows that the adjustment of campus green space factors can reduce the concentration of pollutants by changing the meteorological factors.

Overwintering site selection and associated microclimates for the redbanded stink bug (Hemiptera: Pentatomidae), a non-native pest of soybean.

Cold winter temperatures govern the distribution and abundance of many insect species, but refugia that provide microclimates can moderate temperature-driven mortality. Winter temperatures have been implicated in limiting the survival and range of Piezodorus guildinii (Westwood) (Hemiptera: Pentatomidae; redbanded stink bug), an economically damaging invasive pest in the southeastern United States, but the role of refugia in overwintering survival of this pest is poorly understood. We conducted 2 studies in successive years to evaluate how leaf litter from hardwoods, pines, and soybeans modulate overwintering site selection and survival of P. guildinii. In the second-year study, we also quantified the buffering effect of the 3 leaf litter types compared to ambient conditions and assessed diapause. In the first-year study, we found that stink bugs preferentially dispersed into leaf litter compared with remaining unsheltered on bare soil; no clear preference among leaf litter types was found. In the second year, however, no clear differences were found among leaf litter types and bare soil. Means of daily minimum temperatures under leaf litter were at least 3.0 ±â€…0.9 °C (SE) warmer and generally less variable than ambient conditions. While high mortality in both studies illustrates that more work must be done to fully understand overwintering survival, limited survival through potentially lethal conditions in the first-year study nonetheless emphasizes the possibility of populations persisting and rebounding in the following spring. Furthermore, our study highlights the potential for stink bugs to persist in areas with lethal ambient temperatures by dispersing into widely available substrates.

Cliff-edge forests: Xerothermic hotspots of local biodiversity and models for future climate change.

Cliffs are remarkable environments that enable the existence of microclimates. These small, isolated sites, decoupled from the regional macroclimate, play a significant role in maintaining species biodiversity, particularly in topographically homogeneous landscapes. Our study investigated the microclimate of south-exposed forests situated at the edge of sandstone cliffs in the western part of the North Alpine Foreland Basin in Switzerland and its role in local forest community composition. Using direct measurements from data loggers, as well as vegetation analyses, it was possible to quantify the microclimate of the cliff-edge forests and compare it with that of the surrounding forests. Our results highlighted the significant xerothermic and more variable nature of the cliff-edge forest microclimate, with a mean soil temperature up to 3.72°C warmer in the summer, higher annual (+28%) and daily (+250%) amplitudes of soil temperature, which frequently expose vegetation to extreme temperatures, and an 83% higher soil drying rate. These differences have a distinct influence on forest communities: cliff-edge forests are significantly different from surrounding forests. The site particularities of cliff edges support the presence of locally rare species and forest types, particularly of Scots pine. Cliff edges must therefore be considered microrefugia with a high conservation value for both xerothermic species and flora adapted to more continental climates. Moreover, the microclimate of cliff-edge forests could resemble the future climate in many ways. We argue that these small areas, which are already experiencing the future climate, can be seen as natural laboratories to better answer the following question: what will our forests look like in a few decades with accelerated climate change?

Les falaises sont des milieux remarquables qui permettent l'existence de microclimats. Ces petites surfaces, aux conditions éloignées du climat régional, jouent un rôle important pour la biodiversité, en particulier dans les paysages topographiquement homogènes. Notre étude a porté sur le microclimat de forêts exposées au sud, situées au bord de falaises de molasse, sur le plateau suisse, et sur son rôle dans la composition de la communauté végétale locale. En utilisant des mesures directes provenant d'enregistreurs automatiques de données, ainsi que des analyses de la végétation, il a été possible de quantifier le microclimat des forêts de bord de falaise et de le comparer à celui des forêts environnantes. Nos résultats ont mis en évidence la nature significativement xérothermique et plus variable du microclimat des forêts de bord de falaise, avec une température moyenne du sol jusqu'à 3.72°C plus élevée en été, des amplitudes accrues annuelles (+28%) et journalières (+250%) de la température du sol, qui exposent fréquemment la végétation à des températures extrêmes, et un taux d'assèchement du sol 83% plus élevé. Ces différences ont une influence marquée sur les communautés forestières: les forêts de bord de falaise sont très différentes des forêts environnantes. Elles permettent la présence d'espèces et de types de forêts localement rares, notamment des pinèdes. Les bords de falaise doivent donc être considérés comme des microrefuges à haute valeur de conservation pour les espèces xérothermiques et la flore adaptée à des climats plus continentaux. En outre, le microclimat des forêts de bord de falaise pourrait ressembler au climat futur à bien des égards. Nous soutenons que ces petites zones, qui connaissent déjà le climat futur, peuvent être considérées comme des laboratoires naturels permettant de mieux répondre à la question suivante: à quoi ressembleront nos forêts dans quelques décennies, suite aux changements climatiques?

Impact of coppicing on microclimate and understorey vegetation diversity in an ancient Mediterranean oak forest.

Coppicing is one of the oldest silvicultural practices and is still widely applied to produce renewable energy from broadleaf forests. However, the consequences on microclimate and understorey vegetation are still poorly understood, especially in Mediterranean oak forests. With the ongoing changes in the climate system and global biodiversity loss, a better understanding of how the forest temperature buffering capacity and below-canopy plant community are impacted by coppicing is crucial. Here we quantify microclimate and understorey vegetation changes in adjacent ancient coppice-with-standards and high forest stands dominated by oaks in Italy, where these systems have been applied for a long time. Air and soil temperatures were recorded for 2.5 years, and nested vegetation plots were used to analyse coppicing effects on species composition, taxonomic, phylogenetic, and functional diversity. Coppicing significantly reduced the forest temperature buffering capacity. The mean of the daily maximum temperatures over the entire period was 1.45 °C higher in the coppiced sites, whereas the mean of the daily minimum temperatures was 0.62 °C lower than in the high forest. Coppicing increased understorey species richness by favouring generalist taxa, but significantly decreased the proportion of forest specialists. The understorey community in coppiced forests consisted of more warm-adapted species. Moreover, coppicing also led to a loss of phylogenetic evenness and to shifts in diversity and community weighted mean Leaf Dry Matter content, pointing to habitat filtering and acclimation processes. In sum, we show that coppicing affects microclimate and understory vegetation in a direction that can exacerbate the effects of climate change, negatively affecting the oak forest specialist flora and its phylogenetic evenness.

The functional microclimate of an urban arthropod pest: Urban heat island temperatures in webs of the western black widow spider.

Urbanization alters natural landscapes and creates unique challenges for urban wildlife. Similarly, the Urban Heat Island (UHI) effect can produce significantly elevated temperatures in urban areas, and we have a relatively poor understanding of how this will impact urban biodiversity. In particular, most studies quantify the UHI using broad-scale climate data rather than assessing microclimate temperatures actually experienced by organisms. In addition, studies often fail to address spatial and temporal complexities of the UHI. Here we examine the thermal microclimate and UHI experienced in the web of Western black widow spiders (Latrodectus hesperus), a medically-important, superabundant urban pest species found in cities across the Western region of North America. We do this using replicate urban and desert populations across an entire year to account for seasonal variation in the UHI, both within and between habitats. Our findings reveal a strong nighttime, but no daytime, UHI effect, with urban spider webs being 2-5 °C warmer than desert webs at night. This UHI effect is most prominent during the spring and least prominent in winter, suggesting that the UHI need not be most pronounced when temperatures are most elevated. Urban web temperatures varied among urban sites in the daytime, whereas desert web temperatures varied among desert sites in the nighttime. Finally, web temperature was significantly positively correlated with a spider's boldness, but showed no relationship with voracity towards prey, web size, or body condition. Understanding the complexities of each organism's thermal challenges, the "functional microclimate", is crucial for predicting the impacts of urbanization and climate change on urban biodiversity and ecosystem functioning.