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The Climate Near the Ground
Abstract
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... Geiger est l'auteur d'un ouvrage consacré à l'étude des climats près du sol publié en 1927 et dont la traduction en anglais intitulée The Climate near the Ground publiée en 1950 est mentionnée comme le premier traité explicitement consacré à l'étude des microclimats. Sans mentionner les travaux de Hopkins, Geiger s'intéresse à des problèmes analogues, relatifs aux variations induites par le microclimat sur la croissance des végétaux (Geiger, 1950). À la différence de Hopkins qui avait imaginé modifier les pratiques agricoles grâce à la loi bioclimatique, le but de Geiger est d'encourager l'étude des microclimats afin de tirer parti des phénomènes microclimatiques pour protéger et aménager les cultures (Geiger, 1950 (Landsberg, 1950). ...
... Sans mentionner les travaux de Hopkins, Geiger s'intéresse à des problèmes analogues, relatifs aux variations induites par le microclimat sur la croissance des végétaux (Geiger, 1950). À la différence de Hopkins qui avait imaginé modifier les pratiques agricoles grâce à la loi bioclimatique, le but de Geiger est d'encourager l'étude des microclimats afin de tirer parti des phénomènes microclimatiques pour protéger et aménager les cultures (Geiger, 1950 (Landsberg, 1950). Cet article propose aux particuliers de développer leur connaissance du microclimat où se situe leur maison afin d'en améliorer le confort et éventuellement de réduire les dépenses liées au chauffage ou à la climatisation de leur habitation. ...
... En devenant une méthode de conception en architecture, l'approche bioclimatique inaugurée par Olgyay a indirectement hérité des problématiques soulevées dans l'ensemble des travaux de recherche relatifs aux effets du climat sur les êtres vivants et leurs habitats, des termitières, qui fournissent des leçons d'orientation au climatologue (Geiger, 1950) comme à l'architecte (Olgyay, 1963), jusqu'aux microclimats complexes créés dans les agglomérations urbaines. Malheureusement, la conception bioclimatique a pu être réduite au cours de son développement à une simple application de principes censés réaliser des économies d'énergie, notamment de chauffage, en négligeant que le bioclimatisme auquel elle se réfère agrège des problématiques qui ont été partagées par de nombreuses sciences, comme la géographie humaine, la climatologie ou l'agriculture au cours du XX e siècle. ...
Cet article souhaite étudier la circulation du terme « bioclimatique » à travers les différentes sciences où il a été employé au cours du XX e siècle et les projets scientifiques auxquels il a été associé. Si aujourd'hui ce terme renvoie généralement à l'architecture, et à ce qu'on nomme la conception bioclimatique, il n'est pas issu de l'architecture puisqu'il provient des recherches d'un entomologiste américain du début du XX e siècle nommé Andrew D. Hopkins. D'abord utilisé par Hopkins, puis dans de nombreuses autres sciences par la suite, il a été popularisé avec le développement de la conception bioclimatique en architecture dès 1963. Cet article propose d'étudier comment les significations successivement associées à ce concept se sont manifestées dans les préoccupations propres à l'architecture.
This article aims to study the circulation of the term 'bioclimatic' through the different sciences in which it has been used during the 20th century and the scientific projects with which it has been associated. If today this term generally refers to architecture, and what is called bioclimatic design, it does not come from architecture since it comes from the research of an American entomologist at the beginning of the 20 th century named Andrew D. Hopkins. First used by Hopkins, then in many other sciences thereafter, it was popularized with the development of bioclimatic approach in architecture in 1963. This article proposes to study how the meanings successively associated with this concept were manifested in the concerns specific to architecture.
... The term "microclimate" describes the climatic conditions near the ground or along the vertical forest profile experienced by terrestrial organisms Zellweger et al., 2019). In contrast to free air temperatures, which are highly controlled by elevation and atmospheric processes, temperatures close to the ground are primarily affected by topographic factors and vegetation structures that produce local microclimates through shading, mixing of air, and evapotranspiration (Geiger, 1980;Das et al., 2015;Zellweger et al., 2020). Climatic conditions below forest canopies can vary spatially within the forest (Chen et al., 1999) and differ substantially from the ambient macroclimate: this difference is referred to as microclimatic buffering (Ewers and Banks-Leite, 2013;Zellweger et al., 2020). ...
... This phenomenon resembles the latitude-dependent effect of forests on temperatures: in tropical areas, there is more cooling, while boreal forests cause more warming (Lee et al., 2011;Li et al., 2015). Plant evapotranspiration rates are relative to the solar radiation, ambient temperatures, and water balance (Geiger, 1980;Allen et al., 1998;Davis et al., 2019), decreasing the demand for evapotranspiration at low temperatures caused by elevational lapse rate or cool weather conditions. During clear weather, canopies absorb and reflect most of the incoming solar radiation creating cooler conditions in the understory, together with evapotranspiration, whereas cloud cover causes a total reduction in the incoming short-wave radiation (Geiger, 1980;De Frenne et al., 2021). ...
... Plant evapotranspiration rates are relative to the solar radiation, ambient temperatures, and water balance (Geiger, 1980;Allen et al., 1998;Davis et al., 2019), decreasing the demand for evapotranspiration at low temperatures caused by elevational lapse rate or cool weather conditions. During clear weather, canopies absorb and reflect most of the incoming solar radiation creating cooler conditions in the understory, together with evapotranspiration, whereas cloud cover causes a total reduction in the incoming short-wave radiation (Geiger, 1980;De Frenne et al., 2021). Moreover, while the evapotranspirative cooling mostly offsets warming caused by canopy albedo, at high elevations the albedo effect stays constant, and evapotranspiration decreases (Zeng et al., 2021). ...
Climate change is expected to have detrimental consequences on
fragile ecosystems, threatening biodiversity, as well as food security of
millions of people. Trees are likely to play a central role in mitigating
these impacts. The microclimatic conditions below tree canopies usually
differ substantially from the ambient macroclimate as vegetation can buffer
temperature changes and variability. Trees cool down their surroundings
through several biophysical mechanisms, and the cooling benefits occur also
with trees outside forest. The aim of this study was to examine the effect
of canopy cover on microclimate in an intensively modified Afromontane
landscape in Taita Taveta, Kenya. We studied temperatures recorded by 19
microclimate sensors under different canopy covers, as well as land surface
temperature (LST) estimated by Landsat 8 thermal infrared sensor. We
combined the temperature records with high-resolution airborne laser
scanning data to untangle the combined effects of topography and canopy
cover on microclimate. We developed four multivariate regression models to
study the joint impacts of topography and canopy cover on LST. The results
showed a negative linear relationship between canopy cover percentage and
daytime mean (R2=0.65) and maximum (R2=0.75) temperatures.
Any increase in canopy cover contributed to reducing temperatures. The
average difference between 0 % and 100 % canopy cover sites was 5.2 ∘C in mean temperatures and 10.2 ∘C in maximum
temperatures. Canopy cover (CC) reduced LST on average by 0.05 ∘C per percent CC. The influence of canopy cover on microclimate was shown to vary
strongly with elevation and ambient temperatures. These results demonstrate
that trees have a substantial effect on microclimate, but the effect is
dependent on macroclimate, highlighting the importance of maintaining tree
cover particularly in warmer conditions. Hence, we demonstrate that trees
outside forests can increase climate change resilience in fragmented
landscapes, having strong potential for regulating regional and local
temperatures.
... For example, the pooling of cold air in lowlying terrains, aspect-related exposure to solar radiation, and the temperature lapse rate due to elevation differences are all well documented 20-23 . Although microclimate has been of long-standing interest in ecology, earlier studies had limited scope as they were based on field measurements at single point locations [24][25][26] . Recent advances in remote sensing, big-data processing, and the growing availability of ready-to-use fine-resolution remote sensing datasets have created a renewed interest in microclimate ecology 9,27,28 . ...
... Although microclimate has been of long-standing interest in ecology, earlier studies had limited scope as they were based on field measurements at single point locations [24][25][26] . Recent advances in remote sensing, big-data processing, and the growing availability of ready-to-use fine-resolution remote sensing datasets have created a renewed interest in microclimate ecology 9,27,28 . ...
Temperature is a fundamental driver of species distribution and ecosystem functioning. Yet, our knowledge of the microclimatic conditions experienced by organisms inside tropical forests remains limited. This is because ecological studies often rely on coarse-gridded temperature estimates representing the conditions at 2 m height in an open-air environment (i.e., macroclimate). In this study, we present a high-resolution pantropical estimate of near-ground (15 cm above the surface) temperatures inside forests. We quantify diurnal and seasonal variability, thus revealing both spatial and temporal microclimate patterns. We find that on average, understory near-ground temperatures are 1.6 °C cooler than the open-air temperatures. The diurnal temperature range is on average 1.7 °C lower inside the forests, in comparison to open-air conditions. More importantly, we demonstrate a substantial spatial variability in the microclimate characteristics of tropical forests. This variability is regulated by a combination of large-scale climate conditions, vegetation structure and topography, and hence could not be captured by existing macroclimate grids. Our results thus contribute to quantifying the actual thermal ranges experienced by organisms inside tropical forests and provide new insights into how these limits may be affected by climate change and ecosystem disturbances.
... For example, studies of lizards have explored the use of different parameters for the distribution of preferred body temperatures (PBTs) [9][10][11] or their voluntary thermal maximum (VTmax) [12,13]. However, the critical maximum (CTmax), and more lately subcritical temperatures (SCTmax1h) or temperatures that kill under 1 h exposure, has been used in vulnerability studies of ectothermic animals [13][14][15][16][17]. Although analyses using preferred temperatures point to tropical terrestrial species as the most vulnerable [9,11], studies based on the CTmax [13,14] sometimes oppose this view, marking populations from subtropical and temperate latitudes as more vulnerable. ...
... For example, since long periods of steady warm weather are necessary to make populations vulnerable under the PBT approach, it might be most able to detect vulnerable populations at lower latitudes and coastal areas, where steady temperatures year-round are more likely. Instead, approaches based on an organism's CTmax might be most effective in more continental regions or latitudes at which higher heat peaks occur due to the combined effects of seasonality and continentality [17]. This situation poses two important consequences for the reliability of accepted global patterns in thermal vulnerability [9,13,14,18]. ...
The time-to-thermal-death curve, or thermal death curve, seeks to represent all the combinations of exposure time and temperature that kill individuals of a species. We present a new theoretical function to describe that time in lizards based on traditional measures of thermal tolerance (i.e., preferred body temperatures, voluntary thermal maximum, and the critical thermal maximum). We evaluated the utility of this function in two ways. Firstly, we compared thermal death curves among four species of lizards for which enough data are available. Secondly, we compared the geography of predicted thermal vulnerability based on the thermal death curve. We found that the time to loss of function or death may evolve independently from the critical thermal limits. Moreover, the traditional parameters predicted fewer deleterious sites, systematically situated at lower latitudes and closer to large water bodies (lakes or the coast). Our results highlight the urgency of accurately characterizing thermal tolerance across species to reach a less biased perception of the geography of climatic vulnerability.
... Local vegetation and topography can alter environmental conditions above, near, and below the soil surface (Aalto et al., 2018;Bramer et al., 2018;Geiger, 1965;Lenoir et al., 2013). In the tundra, shading from standing vegetation dominated by shrubs can reduce soil temperatures and soil temperature fluctuations during the growing season (Aguirre et al., 2021;Blok et al., 2010;Kade et al., 2006;Klene et al., 2001;Myers-Smith & Hik, 2013). ...
... Even though our TMS canopy-level sensors actually reached above the low-lying tundra vegetation in 87 of 90 plots (Figure S1), these measurements might still be subject to boundary layer effects from the vegetation (Geiger, 1965). In addition, limited hardiness of the standardized TMS logger shields prevented us from leaving TMS loggers out to monitor canopy-level temperatures throughout winter. ...
Climate warming is inducing widespread vegetation changes in Arctic tundra ecosystems, with the potential to alter carbon and nutrient dynamics between vegetation and soils. Yet, we lack a detailed understanding of how variation in vegetation and topography influences fine‐scale temperatures (‘microclimate’) that mediate these dynamics, and at what resolution vegetation needs to be sampled to capture these effects. We monitored microclimate at 90 plots across a tundra landscape in western Greenland. Our stratified random study design covered gradients of topography and vegetation, while nested plots (0.8 to 100 m2) enabled comparison across different sampling resolutions. We used Bayesian mixed‐effect models to quantify the direct influence of plot‐level topography, moisture and vegetation on soil, near‐surface and canopy‐level temperatures (‐6; 2; and 15 cm). During the growing season, colder soils were predicted by shrub cover (‐0.24 °C per 10% increase), bryophyte cover (‐0.35 °C per 10% increase) and vegetation height (‐0.17 °C per 1 cm increase). The same three factors also predicted the magnitude of differences between soil and above‐ground temperatures, indicating warmer soils at low cover/height, but colder soils under closed/taller canopies. These findings were consistent across plot sizes, suggesting that spatial predictions of microclimate may be possible at the operational scales of satellite products. During winter, snow cover (+0.75 °C per 10 snow‐covered days) was the key predictor of soil microclimate. Topography and moisture explained little variation in the measured temperatures. Our results underline the close connection of vegetation and snow with microclimate in the Arctic tundra, but also point to the need for more studies disentangling their complex interplay across tundra environments and seasons. Future shifts in vegetation cover and height will likely mediate the impact of atmospheric warming on the tundra soil environment, with potential implications for below‐ground organisms and ecosystem functioning.
... This difference in sunlight exposure is likely a key factor explaining the canopy effects observed exclusively during the summer season. These effects are pronounced due to variations in canopy cover, with summer showing a greater seasonality because of the trees providing more effective shading during this period [54,55]. A recent study at Pepperwood Preserve reported that site aspect was the most important determinant of species distributions of trees [42]. ...
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 km ² ) 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.
... However, its offspring could be more vulnerable to host-plant scarcity during summer drought periods. Overall, the different interaction of the butterflies with microclimatic INTRODUCTION Vegetation cover locally modifies climatic conditions and generates a microclimatic regime that deviates from open, free-air, and standardized measurements (i.e., macroclimate; Geiger, 1950;Stoutjesdijk & Barkman, 2014). The absorption and reflection of solar radiation and the evapotranspirative cooling of forest canopies buffer macroclimatic temperatures and reduce thermal variation in the understory (Bramer et al., 2018;De Frenne et al., 2021;Zellweger et al., 2020). ...
Ecotones linking open and forested habitats contain multiple microhabitats with varying vegetal structures and microclimatic regimes. Ecotones host many insect species whose development is intimately linked to the microclimatic conditions where they grow (e.g., the leaves of their host plants and the surrounding air). Yet microclimatic heterogeneity at these fine scales and its effects on insects remain poorly quantified for most species. Here we studied how interspecific differences in the use of microhabitats across ecotones lead to contrasting thermal exposure and survival costs between two closely‐related butterflies (Pieris napi and P. rapae). We first assessed whether butterflies selected different microhabitats to oviposit and quantified the thermal conditions at the microhabitat and foliar scales. We also assessed concurrent changes in the quality and availability of host plants. Finally, we quantified larval time of death under different experimental temperatures (thermal death time [TDT] curves) to predict their thermal mortality considering both the intensity and the duration of the microclimatic heat challenges in the field. We identified six processes determining larval thermal exposure at fine scales associated with butterfly oviposition behavior, canopy shading, and heat and water fluxes at the soil and foliar levels. Leaves in open microhabitats could reach temperatures 3–10°C warmer than the surrounding air while more closed microhabitats presented more buffered and homogeneous temperatures. Interspecific differences in microhabitat use matched the TDT curves and the thermal mortality in the field. Open microhabitats posed acute heat challenges that were better withstood by the thermotolerant butterfly, P. rapae, where the species mainly laid their eggs. Despite being more thermosensitive, P. napi was predicted to present higher survivals than P. rapae due to the thermal buffering provided by their selected microhabitats. However, its offspring could be more vulnerable to host‐plant scarcity during summer drought periods. Overall, the different interaction of the butterflies with microclimatic and host‐plant variation emerging at fine scales and their different thermal sensitivity posed them contrasting heat and resource challenges. Our results contribute to setting a new framework that predicts insect vulnerability to climate change based on their thermal sensitivity and the intensity, duration, and accumulation of their heat exposure.
... However, this would entail a relatively long search, a high exposure to overheating while crossing open patches (Díaz, 1991;Lagarde et al., 2012), and possibly an increased risk of predation (Christian & Tracy, 1981;Díaz, 1992;Herr et al., 2020). Another possibility would be to climb trees to increase perch height, because air temperature decreases, and wind speed increases, far from the ground (Adolph, 1990;Bakken, 1989;Geiger, 1965). In addition, trees tend to be more shaded, and to offer surfaces favouring vertical body orientation and hence lowered T e s Heath, 1964). ...
Although the effects of global warming on thermoregulation are usually explored using predictions of climate envelop modelling, such effects should best be analysed empirically, studying the same population with the same methods after a long enough period of temperature rise.
We used a 30‐year long database about body temperatures ( T b s) of field‐active Psammodromus algirus lizards inhabiting a well‐conserved temperate open forest, and we focused on the summers of 1997 and 2017 to compare T b s, environmental operative temperatures ( T e s), their proximity to the selected thermal range ( T sel ), and the selection of sunlit and shaded patches all along the day. From these data, we estimated the precision (standard deviation of T b s), accuracy (average distance between T b s and T sel ) and effectiveness (extent to which T b s are closer to T sel than T e s) of thermoregulation.
Of the highest 5% of all T b s in the database, 95% were recorded in 2017, when the adjustment to T sel was much better for T b s selected in a laboratory thermogradient than for field T b s (percentages of T b s above T sel of 2% and 52% respectively).
In 2017, especially after 12:00 h, the selection of shaded patches (87% of lizards in full shade vs. <1% in full sun) was more intense than in 1997, contributed more to overall thermoregulation, and produced a larger difference between T e s and T b s. In spite of this, T b s were lower—and closer to T sel —in 1997 (when most shaded patches offered favourable thermal opportunities, with T e s within or below T sel ) than in 2017 (when only 33% of full shade T e s, and 8% of all T e s, were within or below T sel ). As a consequence, estimates of the accuracy and effectiveness of thermoregulation decreased over the 20‐year period examined.
We conclude that given the low availability of T e s within or below T sel , lizards cannot longer prevent the rise of their T b s above T sel , at least in hot summer days. Thus, the effects of global warming are already hindering the ability of lizards to buffer environmental change by behavioural means, even in temperate forests with a fine‐grained mosaic of sun and shade patches.
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... Microclimatic factors such as temperature and humidity have strong impacts on the distribution of dung beetles and can affect their spatial, seasonal, and temporal distributions (Schowalter 2016). Different habitats can constitute distinct microclimates (Geiger and Bouyoucos 1951), which influences the distribution of dung beetles (Nichols et al. 2007;Gardner et al. 2008;Almeida and Louzada 2009;Siqueira Neves et al. 2010). Owing to vegetation cover, closed environments substantially reduce solar radiation on the ground, preserving more moisture and decreasing ambient temperature when compared to open environments (Oliver and Morecroft 2014). ...
In dung beetles, spatial and temporal segregation is determined by the niche and evolutionary history of the species and is mediated by competition. Different functional guilds of dung beetles use this segregation to reduce competitive pressure and optimize usage of ephemeral resources. We sought to understand the spatial (open and closed areas) and temporal (diurnal, nocturnal, and crepuscular periods of activity) segregation of the dung beetle community in the Brazilian Cerrado. We collected dung beetles during the day, dusk, and night in two phytophysiognomies, one representative of open areas and the other of closed areas in two protected areas of the Brazilian Cerrado, and used statistical models to understand how segregation explains richness, total abundance, and abundance of each guild. We collected a total of 2253 individuals and 58 species; 44 from open areas and 22 from closed ones, of which eight were collected in both habitats. Our hypotheses were confirmed, that is, in the Cerrado, the highest abundance of dung beetles occurred in the more closed areas during nocturnal and crepuscular periods, and the highest number of species occurred in the more open areas. The dung beetle community is distinct between different activity periods and phytophysiognomies, and its their functional guilds exhibit preferences for habitat and/or activity periods, according to their ecological characteristics. Therefore, we found that both activity period and habitat type are important for characterizing the dung beetle community, which exhibits different patterns of dominant species and functional guilds throughout the day. Thus, we propose that to determine the species composition of the dung beetle community, one should consider not only the habitat type but also the different periods of activity.
... In our study, while the T air inside both the SCC and PTC was higher than that in the ambient air plot when the solar radiation was >0 W m -2 in the daytime, the T air was lower inside the chambers when solar radiation was 0 W m -2 in the nighttime (Table 1); similar differences were observed for T pan (Table 2). T air changes in a day occur near the water surface and plants first, and then the T air change is transmitted to the above air (Geiger & Stewart, 1950). When the chambers are applied into the plant canopy, the heat balance in nighttime is such that the covers of the chamber themselves, in addition to the plant canopy, act as a cold source against the warmer above air. ...
Rice growth at an elevated air temperature (Tair) during the ripening period is often evaluated using a semi-closed chamber (SCC). However, the water vapor pressure deficit (VPD) and CO2 concentration inside SCCs get lower than at ambient air plot, and these changes affect panicle temperature and photosynthesis. We developed a punched-top chamber (PTC), that is, an SCC with numerous pores on the top, and compared meteorological environments inside the two chambers and of ambient air plot. When solar radiation was >200 W m⁻², ΔTair (SCC – Ambient) was 3.1°C–5.3°C, and ΔTair (PTC – Ambient) was 2.2°C–3.7°C. Excessively high Tair > 38°C were more frequent inside the SCC than the PTC. The changes in VPD and CO2 concentration inside the PTC were less pronounced compared with those of the SCC, and thus PTC can be a better treatment for safely assessing the direct effect of elevated Tair.
... Furthermore, we have identified many other past gravitational events within the FM site (Fig. 3). So far, the main parts are still well ventilated, which results in microclimatic seasonal dynamics (Fig. 9), commonly described in dynamic caves (Geiger, 1966;Faimon and Lang, 2013). In the late cold season in winter and spring, the entrance portion of the Hortense Adit is commonly iced, and frost weathering is gradually destroying the adit profile (Fig. 4d), as is typical for cyclical or Fig. 11. ...
We have investigated a typical abandoned underground slate mine situated in the Bohemian Massif (Central Europe) in order to describe its elementary components and to outline the varied relations among them. Based on the results from geological, geomorphological, hydrological, microclimatic, and biological investigation, we have defined the abandoned underground mine as an important but overlooked semi-natural ecosystem that represents an azonal and relatively fast evolving environment. Unlike any other studies published so far, we have found it also vulnerable in terms of fragility and time-limited stability. Our results together with a comprehensive discussion highlight the fundamental features of the abandoned underground mine and finally serve as a basis on which we introduce a conceptual model of the abandoned underground mine. The complex and interdisciplinary perception of abandoned underground mines is crucial for appropriate environmental assessment, tourist management, natural protection or remediation.
... In addition, the topography of the area (e.g. north facing slope and local depression) theoretically makes a slightly colder microclimate possible: the north facing slopes are generally characterized by shorter growing seasons, less solar radiation and lower maximum temperature (Dobrowski, 2011;Geiger and Bouyoucos, 1951;Körner, 2003). On the one hand, the steep slopes can also be dry, as the soil layer is shallow and water runoff is high (Dobrowski, 2011), on the other hand, the convergent environments (basins, local depressions, sinks) pool cool air and accumulate soil and water (Dobrowski, 2011). ...
Although several studies provide a broad overview of vegetation changes in the Carpathian Basin during the Holocene, stand-scale vegetation changes are lesser known because of the rarity of suitable sampling sites. In this study we investigated the sediment of a small closed-canopy site (Nagy-forrás forest hollow, 685 m a.s.l., 0.1 ha), located in the Mátra Mountains, on the north facing slope of Kékes (1014 m a.s.l.). We carried out detailed pollen, conifer stomata and plant macrofossil analyses, as well as radiocarbon dating to examine Late Glacial and Holocene dynamics of vegetation development. The site dates back to ca. 15,500 cal yr BP, when open boreal forests and wet tundra-like habitats occurred around the hollow. Closed forest cover developed around 14,600 cal yr BP, when a boreal European larch-Swiss stone pine ( Larix decidua-Pinus cembra) forest surrounded the hollow. This vegetation type remained stable up to 7700 cal yr BP. We observed a hiatus between 7700 and 2710 cal yr BP, followed by a beech ( Fagus sylvatica) dominated mixed temperate deciduous forest. Our results confirmed that the area was covered by a primary forest, as human influence was visible only from 175 cal yr BP. The relatively long lasting persistence of Pinus cembra in the Holocene at relatively low altitude was documented, which has never been found in Holocene sediments in the Pre-Carpathians before. We hypothesize that the north facing slope acted as a cold-stage refugium in the Early Holocene and could play the same role for the present-day beech forest that is threatened by recent climate change.
... However, in this study, the variations in hysteresis times for the maximum and minimum daily mean ground temperatures were complicated. It is well known that the process governing the energy transfer between the ground and atmosphere is complex (Beltrami and Kellman, 2003;Geiger, 1965) and that it is affected by soil moisture variations (Gao, 2005;Gao et al., 2003;Hopmans et al., 2002), precipitation, evapotranspiration (Jencso et al., 2009), vegetation cover (Hu et al., 2019) and freeze-thaw processes (Li et al., 2014). Therefore, future studies are required to find a general mathematical method that can determine hysteresis times and which can provide improved ground temperature simulation results. ...
Air and ground temperatures are important factors contributing to land and atmosphere processes as well as ecosystem dynamics. This paper presents a simple model for simulating ground temperature from air temperature in the permafrost regions on the Qinghai-Tibetan Plateau (QTP). The model takes hysteresis between daily air temperature and ground temperature into consideration as well as exponential and linear functions for annual average ground temperatures at different depths. Results indicate an evident hysteresis in ground temperature with increasing depth. By taking hysteresis into account, the developed model provides improved daily ground temperature estimates compared to those obtain from the original linear regression, at Xidatan (site QT09) and Kunlun Pass (site CN06) in the permafrost regions on the QTP, with an average root mean square error (RMSE), normalized standard error (NSEE), and mean absolute error (MAE) of 1.12 °C, 0.41, and 0.84 °C for QT09, and 1.41 °C, 0.29 and 1.10 °C for CN06, respectively, at all depths. The results indicate that the model that takes hysteresis into account provides monthly ground temperatures that are closest to field observations, with an average RMSE, NSEE, and MAE of 0.63 °C, 0.24, and 0.50 °C, respectively, at QT09 site and 0.92 °C, 0.18 and 0.63 °C, respectively, at CN06 site. In addition, the simulation accuracy of the average annual ground temperature is significantly improved by using the combined exponential and linear model, and this is particularly relevant when drilling boreholes at great depths in permafrost regions. Therefore, these models provide a useful and simple method for simulating ground temperature and modeling permafrost changes under global warming conditions.
The article discusses the use of linear, polynomial and k-dimensional general linear fit for fitting the Keeling Curve in the LabVIEW environment. Description of mathematical models and equations for linear, polynomial and k-dimensional general linear fitting, virtual instruments developed in the LabVIEW environment for curve fitting and extrapolation, as well as the curve fitting and extrapolation results for all considered approximation types in formulaic and graphical forms are presented. Statistical estimates of the different approximation type accuracy are given in the form of calculated standard deviation and variance. With reference to historical and modern studies of the atmospheric CO 2 and global warming level, importance and significance of the problem under discussion and of the study carried out are shown. In particular, the article demonstrates that the Keeling Curve approximation and extrapolation are having a polynomial component, and the CO 2 concentration level is characterized by the polynomial growth. The article presents a method for taking into account the Keeling Curve shape during approximation by using the k-dimensional general linear fit and a special functions basis with high accuracy in approximating the curve cyclic shape. The conclusions made provide areas for future research on this topic.
https://ieeexplore.ieee.org/document/10479827
The increasing use of outdoor housings for temperature-sensitive apparatus, coupled with the growing interest in adhesive-bonded structures for building constructions, aircraft, armaments, etc., has prompted a growing concern over the effects of solar heating on such structures. Vagaries of local weather conditions provide little cause for confidence in short-term outdoor exposures as a means for determining extremes of temperatures which may occur in structures over extended periods of time and in a variety of geographical locations. Potential minimum temperatures can be established solely on the basis of observed minima for the area concerned, taken from records of the Weather Bureau. Maximum temperatures of exposed structures are, on the other hand, subject largely to the absorption of thermal energy from the sun, a quantity which can vary widely due to a number of natural and manmade factors. Much has been written regarding the intensity of solar radiation and its effect on climate, but relatively little information is available to the designer and the materials engineer regarding the temperatures which may occur in structures due to solar heating. The little that does appear in the literature generally concerns specific items, for example, wooden aircraft wings, roof structures, transformers, etc. In this paper, the author will review the more important factors involved in solar heating and will summarize available temperature data on various exposed structures from published and unpublished sources. Following this, an attempt will be made to suggest temperature maxima for consideration in design and in simulated exposure tests for sandwich and other structures which may be exposed to the weather.
Comprehensive precipitation data is essential for hydrological, agricultural, and climatological studies. Yet, gaps and sparse rain gauge distribution pose challenges, requiring imputation algorithms to fill data gaps. The aim of this research is to evaluate the performance of several approaches for estimating incomplete precipitation data in the Upper Indus Basin (UIB). Eight various imputation approaches were used on sparsely gauged mountainous UIB on a monthly time series of twenty-four meteorological observatories. Following that, the estimation approaches were evaluated using a rank-based approach comprising four different statistical indicators. The results indicate that multiple linear regression is the best-performing strategy for most of the stations regardless of season or orography, followed by the arithmetic average method and inverse distance weighing method.
Despite the nearly ubiquitous nature of sleep in the animal kingdom, behavioural research on sleep has focused on a few model organisms and widespread behaviours studied in artificial laboratory settings. In this study, we examine the ontogeny of sleeping perch selection in four closely related species of arboreal lizard in situ. The study species each occupy similar habitats and share ‘solitary’ ecology wherein potential lizard competitors are absent, thus providing four partially independent replicates with which to test hypotheses. We find that structural niche, analysed as perch height, varies by age and sex. Males sleep higher than females and adults sleep higher than juveniles in three of four species. Adults exhibit greater variability in sleep site selection. These patterns may reflect diurnal behaviour or indicate selective differences in sleeping perch variability across sex and ontogeny.
Este artículo tiene como objetivo establecer una nueva catalogación de arquitecturas a partir de su forma de gestionar el clima con el fin de resituar la gestión climática del espacio y el papel de su habitante como material fundamental del proyecto arquitectónico. En un recorrido que sigue las investigaciones sobre las cualidades térmicas en los edificios de Lisa Heschong, pasando por los planteamientos sobre la pérdida de relación con el clima de Eva Horn, para finalmente complementar los modos de gestión climática propuestos por Reyner Banham. Se desarrollan ejemplos de los cuatro modos en su estado puro: Retardante, Hermético, Selectivo y Regenerativo; separándolos conceptualmente para incorporarlos como material arquitectónico de una manera necesariamente combinada. Y así volver a establecer una relación activa entre las experiencias habitables y la riqueza de las variaciones climáticas.
It is crucial to make the most efcacious usage of solar radiation, one of the renewable energy sources increasing every day.
In order to make practical usage of solar radiation, it is necessary to correctly adjust the solar panel tilt angle that collects
solar radiation. Solar panel tilt angles were optimized using isotropic and anisotropic models for the frst time in Eskisehir,
Turkey. This study applied a mathematical model to identify the ideal tilt angles for solar panels. A combination of selected
anisotropic and isotropic models was used in the calculations. The Turkish State Meteorological Service’s archived data were
used. The optimal tilt angles for monthly, seasonal, and annual solar panels were established. It has been discovered that the
annual optimum solar panel tilt angle should be set to 33° in the isotropic model, whereas in the anisotropic model, to 35°. It
was found that the anisotropic model approach is more advantageous than the isotropic approach in collecting solar radiation
at a fxed optimum tilt angle. These fndings may serve as examples for locations at diferent coordinates at the same latitude.
Insects are declining, but the underlying drivers and differences in responses between species are still largely unclear. Despite the importance of forests, insect trends therein have received little attention. Using 10 years of standardized data (120,996 individuals; 1,805 species) from 140 sites in Germany, we show that declines occurred in most sites and species across trophic groups. In particular, declines (quantified as the correlation between year and the respective community response) were more consistent in sites with many non-native trees or a large amount of timber harvested before the onset of sampling. Correlations at the species level depended on species’ life-history. Larger species, more abundant species, and species of higher trophic level declined most, while herbivores increased. This suggests potential shifts in food webs possibly affecting ecosystem functioning. A targeted management, including promoting more natural tree species composition and partially reduced harvesting, can contribute to mitigating declines.
Purpose
The sensitivity of wildland plants to temperature can be directly measured using experimental manipulations of temperature in situ. We show that soil surface temperature and plant density (per square meter) have a significant impact on the germination, growth, and phenology of Bromus tectorum L., cheatgrass, a short-statured invasive winter-annual grass, and assess a new experimental temperature manipulation method: the application of black and white gravel to warm and cool the soil surface.
Methods
We monitored height, seed production, and phenological responses of cheatgrass, seeded into colored gravel at low and high densities at two sites in the western USA: Boise, ID and Cheyenne, WY. Soil surface temperature and volumetric water content were measured to assess treatment effects on soil surface microclimate.
Results
Black gravel increased mean temperatures of the surface soil by 1.6 and 2.6 °C compared to white gravel in Cheyenne and Boise, respectively, causing 21–24 more days with soil temperatures > 0 °C, earlier cheatgrass germination, and up to 2.8-fold increases in cheatgrass height. Higher seeding density of cheatgrass led to 1.4-fold taller plants on black gravel plots at both sites, but not white gravel at the Boise site, indicating a possible thermal benefit or reduction of water demand due to plant clustering in warmer treatments.
Conclusions
Manipulating soil-surface albedo altered the soil microclimate and thus growth and phenology of cheatgrass, whose life history and growth form confer a strong dependency on soil-surface conditions.
Wind farms have been proved to have potential impact on the ecology. As an important ecological factor, soil moisture has a great impact on the ecosystem. Therefore, it is of great significance to explore the effect of wind farms on soil moisture. At present, the remote sensing data can be used to calculate the soil moisture of wind farm conveniently, but its spatial resolution is poor. Moreover, the measured soil moisture can't express the spatial difference. Therefore, through the effective combination of remote sensing data and measured data, this method can accurately judge the impact of wind farm on soil moisture. This method investigated wind farms located in the grasslands of China. Remote sensing images and field data were used to explore the area and extent of influence of wind farms on grassland soil moisture. We use Landsat images and field measurements to derive a linear relationship between the soil moisture and the TVDI, which was calculated based on the land surface temperature and NDVI, was developed in this work. The correlation was used to reverse spatial distribution map of soil moisture before and after the construction of wind farms. The diurnal and seasonal variation of the influence of the wind farm on the grassland soil moisture was also judged.
This method of combining measurement and remote sensing provides a reference for analysing the influence of wind farms on soil moisture.
This method can be used for reference to compare the meteorological factors of different wind directions before and after the construction of wind farms.
The Source-Path-Receiver Model (SPRM) is a fundamental concept derived from hazard (including noise) control. It is useful in studies of animal bioacoustics where the sound sources may be animals, humans, or natural events within the habitat and the receivers are animals. It provides a framework for the researcher to ensure all aspects of the scenario being observed or recorded are considered, which could affect the observations. This chapter develops the SPRM for the example of animal acoustic communication, where the source and receiver are animals of the same species. Factors that affect the source and receiver are explained (e.g., age, sex, individual identity, and context). Much emphasis is given to “the path.” The environment through which the sound travels affects the received signal (in terms of its amplitude, frequency, and duration) and exhibits ambient noise, which might affect both sender and receiver. The basic concepts of sound propagation are explained (including Huygens’ principle, ray tracing, Snell’s law, reflection, scattering, reverberation, diffraction, refraction, transmission, absorption, ground effect, atmosphere effects, acoustic mirages, and shadow zones). The SPRM illustrates the importance of exploring the acoustic features of a sound signal at all points between the sender and receiver to understand factors that could promote or inhibit effective communication among animals.
These studies on the effect of climatic environment on cambium temperatures are indicative of why so much cold injury occurs in the Southeast. High cambium temperatures occurring in late winter as the result of solar radiation impinging on the bark of the trunk caused a loss of hardiness after the rest period had been broken. When these high daytime temperatures were followed by a rapid rate of fall to freezing temperatures at night, severe injury often resulted, which contributed greatly to shortening the life of peach trees. In addition, wind produced local cooling of the cambium tissue and, at critical air temperatures in late winter and early spring, was capable of causing severe cold damage. Trunk insulators modified the microclimate around the tree to the extent of preventing the extremes that made the trees less hardy and more subject to low temperature injury. Trunk cambium temperature appeared to be a sensitive indicator of tree vitality during growth. Trees with low vitality had higher cambium temperature than trees in good condition.
Context
Both climatic extremes and land-use change constitute severe threats to biodiversity, but their interactive effects remain poorly understood. In forest ecosystems, the effects of climatic extremes can be exacerbated at forest edges.
Objectives
We explored the hypothesis that an extreme summer drought reduced the richness and coverage of old-growth forest species, particularly in forest patches with high edge exposure.
Methods
Using a high-resolution spatially explicit precipitation dataset, we could detect variability in drought intensity during the summer drought of 2018. We selected 60 old-growth boreal forest patches in central Sweden that differed in their level of drought intensity and amount of edge exposure. The year after the drought, we surveyed red-listed and old-growth forest indicator species of vascular plants, lichens and bryophytes. We assessed if species richness, composition, and coverage were related to drought intensity, edge exposure, and their interaction.
Results
Species richness was negatively related to drought intensity in forest patches with a high edge exposure, but not in patches with less edge exposure. Patterns differed among organism groups and were strongest for cyanolichens, epiphytes associated with high-pH bark, and species occurring on convex substrates such as trees and logs.
Conclusions
Our results show that the effects of an extreme climatic event on forest species can vary strongly across a landscape. Edge exposed old-growth forest patches are more at risk under extreme climatic events than those in continuous forests. This suggest that maintaining buffer zones around forest patches with high conservation values should be an important conservation measure.
Air pollution is a serious environmental problem in Latin American cities. Although the problem is widely studied, collaborative solutions from city planners and urban climatologists have been slow to evolve. In this article, we demonstrate the severity of the problem in the mountain city of Manizales, Colombia, and offer “urban climatic mapping” as an appropriate tool to ease communication between scientists and planners. We take a comprehensive approach involving topographic, demographic, and atmospheric datasets, which are assembled and analysed in a GIS environment. Our maps show that the mountain-valley wind patterns in Manizales are critically important for ventilating the city and improving air quality. We therefore give planning recommendations to protect and enhance the natural airsheds and airflow systems of Manizales through modification of the built form. Recommendations are also given to reduce pollutant loading in the narrow streets of the historical centre, and to expand the network of environmental monitoring stations across the city. The expansion is designed in accordance with international guidelines for siting meteorological instruments in urban areas, and is intended to serve new uses for the network data, to include community planning, environmental mapping, and urban climate education.
Small, volant and nocturnal, bats face strong challenges to avoid heat loss. Among aerial insectivores, body mass varies by two orders of magnitude between the smallest and the largest species. At low temperatures, physiological constraints should be harsher for smaller bats, as they lose more heat through their body surface than larger species. So, temperature variations should lead to distinct behavioural responses by bats of different body masses. Also, because they feed on arthropods, dependent on ambient temperature, aerial insectivores should halt feeding at low temperatures. Using ultrasound detectors and temperature and humidity sensors, we investigated how aerial insectivores of the coldest region in austral Brazil respond to nightly temperature variations and compared those responses between guilds of distinct body masses. We predict that smaller bats reduce their activity faster than larger bats, but that foraging should reduce simultaneously in the two guilds, as they depend on ectothermic prey. Bat activity reduced significantly below 12 °C. Larger bats maintained their activity at temperatures where the activity of smaller bats had already halted. However, larger bats foraged mostly during the first half of the night, at higher temperatures than those chosen by smaller bats to forage. We associate these differential responses to the thermal convection process, which may increase prey availability at higher altitudes, where larger molossids are known to forage. Smaller species, mostly edge-space hunters, probably take advantage of less variable prey availability during the night, resulting in a more regular behavioural pattern of navigation and foraging.
Species- and trait-environment linkages in forest plant communities continue to be a frequent topic in ecological research. We studied the dependence of floristic and functional trait composition on environmental factors, namely local soil properties, overstory characteristics, climatic parameters and other abiotic and biotic variables. The study area comprised 50 monitoring plots across Slovenia, belonging to the EU ICP Forests monitoring network. Vegetation was surveyed in accordance with harmonized protocols, and environmental variables were either measured or estimated during vegetation sampling. Significant predictors of species composition were identified by canonical correspondence analysis. Correlations between plant traits, i.e. plant growth habit, life form, flowering features and CSR signature, were examined with fourth-corner analysis and linear regressions. Our results show that variation in floristic composition was mainly explained by climatic parameters (mean annual temperature, mean annual precipitation), soil properties (pH) and tree layer-dependent light conditions. Trait composition was most closely related with tree layer characteristics, such as shade-casting ability (SCA, a proxy for light availability in the understory layer), tree species richness and tree species composition. Amongst soil properties, total nitrogen content and soil texture (proportion of clay) were most frequently correlated with different species traits or trait states. The CSR signature of herb communities was associated with tree layer SCA, soil pH and mean annual temperature. The floristic composition of the studied herb-layer vegetation depended on temperature and precipitation, which are likely to be influenced by ongoing climate change (warming and drying). Trait composition exhibited significant links to tree layer characteristics and soil conditions, which are in turn directly modified by forest management interventions.
Key message
Based on a large set of experimental data, this research shows a significant spatial-variation of throughfall (TF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathrm{TF}$$\end{document}) underneath canopies and proposes multi-point sampling approach for precise TF measurements.
Abstract
Throughfall (TF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathrm{TF}$$\end{document}) exhibits excessive spatial variability in its measurements under a tree canopy. This study proposes multiple sampling for more accurate TF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathrm{TF}$$\end{document} estimation, suggesting positioning configuration of receptacles under trees. Total 106 rainfall (R) events of cumulative rainfall depth 1741.5 mm that occurred during monsoon seasons of 2017–18 were considered. Single-factor ANOVA analysis showed significant variation in TF under nine different plantations. Relative TF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathrm{TF}$$\end{document} (TF′\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathrm{TF}}^{{\prime}}$$\end{document}) varied from 56.4 to 84.2% with a mean of 71.7% of R. For three event classes for R (2.8–20 mm), (20–40 mm), and > 40 mm, mean TF′\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathrm{TF}}^{{\prime}}$$\end{document} values were 71%, 73%, and 74%, respectively. As expected, the spatial variability of TF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathrm{TF}$$\end{document} decreased with increasing rainfall depths; the rainfall events smaller than 2.8 mm were completely retained by the tree canopy, implying that the interception is high during small magnitude rains. The lowest mean relative difference and root mean square error of relative difference (RMSE_RD) values were obtained for the receptacles placed at a distance of 100 cm, 150 cm, and 200 cm from the tree stem, exhibiting TF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathrm{TF}$$\end{document} sampling at the middle of the canopy radius to be more stable (in time) than towards canopy edge or very near to the tree stem. TF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathrm{TF}$$\end{document} inconsistency on either side of the tree canopy represents the variability of TF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathrm{TF}$$\end{document} with the direction from tree stem. Thus, TF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathrm{TF}$$\end{document} varied with both location and direction under a tree canopy. TF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathrm{TF}$$\end{document} obtained using the proposed multi-sampling procedure showed significantly lower variability than that measured conventionally at a random point under a tree canopy, and thus, underscores its importance in formulation of a throughfall sampling strategy.
The impact of various modifications of the JSBACH Land Surface Model to represent soil temperature and cold-region hydro-thermodynamic processes in climate projections of the 21st century is examined. We explore the sensitivity of JSBACH to changes in the soil thermodynamics, energy balance and storage, and the effect of including freezing and thawing processes. The changes involve 1) the net effect of an improved soil physical representation and 2) the sensitivity of our results to changed soil parameter values and their contribution to the simulation of soil temperatures and soil moisture, both aspects being presented in the frame of an increased bottom boundary depth from 9.83 m to 1418.84 m. The implementation of water phase changes and supercooled water in the ground creates a coupling between the soil thermal and hydrological regimes through latent heat exchange. Momentous effects on subsurface temperature of up to ±3 K, together with soil drying in the high northern latitudes, can be found at regional scales when applying improved hydro-thermodynamic soil physics. The sensitivity of the model to different soil parameter datasets occurs to be low but shows important implications for the root zone soil moisture content. The evolution of permafrost under pre-industrial forcing conditions emerges in simulated trajectories of stable states that differ by 4 – 6 • 10 ⁶ km ² and shows large differences in the spatial extent of 10 ⁵ –10 ⁶ km ² by 2100, depending on the model configuration.
NASA’s Mars 2020 (M2020) rover mission includes a suite of sensors to monitor current environmental conditions near the surface of Mars and to constrain bulk aerosol properties from changes in atmospheric radiation at the surface. The Mars Environmental Dynamics Analyzer (MEDA) consists of a set of meteorological sensors including wind sensor, a barometer, a relative humidity sensor, a set of 5 thermocouples to measure atmospheric temperature at ∼1.5 m and ∼0.5 m above the surface, a set of thermopiles to characterize the thermal IR brightness temperatures of the surface and the lower atmosphere. MEDA adds a radiation and dust sensor to monitor the optical atmospheric properties that can be used to infer bulk aerosol physical properties such as particle size distribution, non-sphericity, and concentration. The MEDA package and its scientific purpose are described in this document as well as how it responded to the calibration tests and how it helps prepare for the human exploration of Mars. A comparison is also presented to previous environmental monitoring payloads landed on Mars on the Viking, Pathfinder, Phoenix, MSL, and InSight spacecraft.
Snow can fall and cover the ground at alpine elevations at any time of the year and at all latitudes. Higher plants can be found in habitats of mean snow duration of anywhere between 320 and a few days (in the tropics) per year.
Walking across an alpine fell field on a bright day, the mountaineer may find it still chilly and windy, and ‘dry’ air may dehydrate the skin. A nearby meteorological station with all its weather masts confirms: +4 °C air temperature, 5 ms–1 wind speed, 40 % relative humidity. While our mountaineer experiences the harsh life in the mountains, the world looks different for those who stay close to the ground. Micrometeorological research in alpine vegetation has shown that, under the conditions described above, the climate within a compact leaf canopy a few centimeters above the ground, for instance in cushion plants, may be +27 °C, saturated air humidity and no convective air movement—life in a humid tropical forest?
Background
The forelands of retreating glaciers are invaluable natural laboratories in which to explore the processes of primary succession. Numerous studies have been conducted on foreland chronosequences to identify temporal and spatial trends of the successional communities. This study focused on the spatio-temporal distribution of three woody plant species on the foreland of a retreating glacier in southern Iceland where historical observations provide precise age control of the moraines. To evaluate colonization and successional trends, we examined which species increase in abundance with time and tested the role of proximity to a seed source in colonization. Additionally, we quantified the rate at which biomass carbon is added to the landscape.
Results
The density of stems of Betula pubescens increases with moraine age across the foreland chronosequence while the density of stems of both Salix lanata and Salix phylicifolia decreases. We found low statistical significance to the relationship between the density of B. pubescens and distance from a forested ridge nor did we find a relationship between the lengths of the stems and the moraine ages. Woody biomass increased fastest during early successional stages and reached a maximum of 28.5 g C m − 2 on the oldest moraine.
Conclusions
Early colonization of moraines was controlled by environmental filters which favored both Salix species. Colonization by B. pubescens followed as environmental factors, e.g., favorable soil properties, improved. We found no conclusive evidence that proximity to a potential source of B. pubescens propagules was a significant factor in controlling colonization. The assumption that the abundance of individuals increased with time through later successional stages proved valid for B. pubescens , but not for either species of Salix . These findings are consistent with the classical spatial successional model of community homogenization. Thus, general successional processes at the landscape scale control the temporal dynamics of individual species.
This essay intends to outline a synthetic excursus on the origin and development of the approach relating architecture to climate in the works of researchers and architects, as an extensive interpretation of what is called in this book bioclimatic architecture.
Using data for 3 days in the Cooperative Atmosphere-Surface Exchange Study 1997 field experiment that are analyzed in LeMone et al. (Boundary-Layer Meteorol 104:1–52, 2002, hereafter L2002), it is shown that direct radiative heating can have a significant role in warming the nearly cloudless fair-weather convective boundary layer (CBL). Radiative heating becomes especially important in the presence of aerosols in the CBL, with a moist layer above the CBL also contributing. Not only does inclusion of radiative heating help “close” their potential-temperature budgets, but it affects entrainment estimates. Combined, radiative heating rates are of the order of 0.2 K h⁻¹, based on calculations using the Rapid-Radiative Transfer Model for general circulation models (RRTMG) code in a single-column version of the Advanced Research Weather Research and Forecasting model and estimates of aerosol heating published in L2002. Our current estimates of clear-air direct radiative heating differ from the estimates in L2002 because the surface skin temperature was not included in the earlier calculations. Upwelling and downwelling longwave radiation computed using the RRTMG code agrees with aircraft measurements within 10–15 W m⁻².
Extremely high temperatures, which negatively affect the human health and plant performances, are becoming more frequent in cities. Urban green infrastructure, particularly trees, can mitigate this issue through cooling due to transpiration, and shading. Temperature regulation by trees depends on feedbacks among the climate, water supply, and plant physiology. However, in contrast to forest or general ecosystem models, most current urban tree models still lack basic processes, such as the consideration of soil water limitation, or have not been evaluated sufficiently. In this study, we present a new model that couples the soil water balance with energy calculations to assess the physiological responses and microclimate effects of a common urban street-tree species (Tilia cordata Mill.) on temperature regulation. We contrast two urban sites in Munich, Germany, with different degree of surface sealing at which microclimate and transpiration had been measured. Simulations indicate that differences in wind speed and soil water supply can be made responsible for the differences in transpiration. Nevertheless, the calculation of the overall energy balance showed that the shading effect, which depends on the leaf area index and canopy cover, contributes the most to the temperature reduction at midday. Finally, we demonstrate that the consideration of soil water availability for stomatal conductance has realistic impacts on the calculation of gaseous pollutant uptake (e.g., ozone). In conclusion, the presented model has demonstrated its ability to quantify two major ecosystem services (temperature mitigation and air pollution removal) consistently in dependence on meteorological and site conditions.
The current study focuses on the RegCM4.5 model and specifically on a comparison of hydrostatic and non‐hydrostatic approaches as well as on different microphysical parameterisations and planetary boundary layer (PBL) schemes. The main goal of the paper is to simulate the historical regional precipitation characteristics of the Carpathian region as reliably as possible. For this purpose, seven different model experiments at a 10 km horizontal resolution were completed for a 10‐year period (1981–1990) using ERA‐Interim reanalysis data (with 0.75° resolution) as initial and boundary conditions. Our simulation matrix consists of hydrostatic and non‐hydrostatic runs together with different treatments of moisture, namely, the SUBEX and the NogTom schemes. In addition, two PBL schemes are tested, the Holtslag and the UW‐PBL scheme. In this detailed validation study, RegCM outputs (e.g., temperature, global radiation, cloud cover, precipitation) are compared to the homogenized, gridded CarpatClim data (available with 0.1° resolution) that are based on measurements at regular meteorological station sites. The validation considers seasonal and monthly means, as well as extreme climatic events. On the basis of the results we can conclude that the role of the non‐hydrostatic core can be clearly recognized for precipitation, particularly over mountains. Moreover, it was also found that the UW‐PBL scheme performs with a negative bias regarding atmospheric boundary layer thickness and temperature and it reduces the wet/dry biases of the Holtslag PBL scheme. Regarding microphysical schemes, the NogTom scheme performs better than the SUBEX scheme, but the modified SUBEX (SUB4.3) can also reduce the precipitation over mountainous areas.
In an era of climate change, the availability of empirical data on alpine summit vegetation in the Himalaya is still scarce. Here we report the assessment of alpine summit flora in Gulmarg Wildlife Sanctuary, Kashmir Himalaya. We employed a globally standardized Multi-Summit Approach and four spatially isolated summits spanning an elevation gradient of 210 m (between 3530-3740 m a.s.l.) from natural treeline to nival zone. Sampling of the summits was carried out in the year 2018 to collect floristic data together with records of soil temperature. A total of 142 vascular plant species were recorded in the sampled summits. Majority of the species were of herbaceous growth form and with perennial life span. Based on Raunkiaer's life form, hemicryptophytes were the most dominant followed by therophytes and phanerophytes. The summit flora showed the predominance of narrow-endemic species, with broad-and non-endemics declining with elevation. A significant relationship between growth form, Raunkiaer's life form, and the degree of endemism with elevation was observed. Both species diversity and soil temperature showed a monotonic decrease with increasing elevation. Interestingly, soil temperature clearly determined the magnitude of species diversity on the summits. Furthermore, based on floristic composition, the lowest summit had the highest dissimilarity with the rest of the summits. The present study employed globally standardized protocol to scientifically assess the patterns of plant diversity on the alpine mountain summits of Kashmir Himalaya, which in turn has wide implications towards long-term monitoring of climate change impact on alpine biodiversity in the rapidly warming Himalaya. Citation: Hamid M, Khuroo AA, Malik AH, et al. (2020) Assessment of alpine summit flora in Kashmir Himalaya and its implications for long-term monitoring of climate change impacts. Journal of Mountain Science 17.
Disparate rates of micro- and macroclimate warming forge future biodiversity and ecosystems
In the Baikal region, warming under conditions of climate continentality is accompanied by an increase in the area of forest fires and the risk that postpyrogenic ecosystems will not return as forests. A study of pine forests on sand sediments in the southeastern Baikal region showed that the regional ecosystems damaged by fire develop in different directions depending on the type of fire and local conditions. After a ground fire, an adult forest stand is preserved and stable signs of pyrogenesis in the soil are developed in the form of charred epipedons. Under these conditions, sparse-grass and dead-cover open stands are formed with almost no signs of renewed young growth and shrubs. The coal effect causes a decrease in soil acidity, an increase in the content of exchangeable calcium, the formation of humus of humate composition, and base unsaturation. It is proposed to identify the soils with coal epipedons at the level of subtype as psammosoils humic postpyrogenic. After a top fire, the plant cover and the soil cover are completely destroyed; the ecosystem begins its development from scratch. Forest renewal in lowlands and on the slopes of shadow and leeward expositions occurs actively in a natural way, as well as against the background of reforestation.During the postfire period, psammosoil humic soil of a weakly developed order is formed under the young forest. On the slopes of solar upwind expositions, unforested deflation zones with no signs of soil formation are formed despite the actions taken to restore the forest stand. Remote sensing methods made it possible to ascertain that, over 15 years of postfire development, despite the reforestation, the area of unforested deflation zones has increased 11-fold when compared to the prefire period. It is recommended to introduce forest-stand restoration in the form of loosening the charred soil on the territories damaged by ground fires, as well as the repeated execution of forest planting works in the deflated areas considering the protection of the forest edges from wind into a set of measures to restore forest ecosystems after wildfires.
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