Dry Summer Research Articles

How can urban green spaces be planned to mitigate urban heat island effect under different climatic backgrounds? A threshold-based perspective

Urban green space (UGS) was widely regarded as an effective nature-based solution to mitigate the urban heat island (UHI) effect, therefore, developing landscape strategies to enhance its cooling intensity (CI) is crucial. However, two main problems prevent the application of results to practical actions: one is the inconsistency of relationships between influencing factors of landscape and the thermal environment; another is the unfeasibility of some common conclusions such as simply increasing the amount of vegetation cover in highly-urbanized areas. This study compared the CIs of UGSs, investigated the influencing factors of CI and identified the absolute threshold of cooling (ToCabs) of the influencing factors in four Chinese cities with very different climatic backgrounds (Hohhot, Beijing, Shanghai and Haikou). Results demonstrate that local climate condition affects the cooling effect of UGS. The CI of UGS is weaker in cities with humid and hot summer than in cities with dry and hot summer. Patch characteristics (area and shape), the percentage of water bodies within the UGS (Pland_w) and neighboring greenspace (NGP), vegetation abundance (NDVI) and planting structure together can explain a significant proportion (R2 = 0.403–0.672, p < 0.001) of the CI variations of UGS. The inclusion of water bodies can ensure effective cooling of UGS, except in the tropical city. Besides, ToCabs of area (Hohhot, 2.6 ha; Beijing, 5.9 ha; Shanghai, 4.0 and Haikou, 5.3 ha), and NGP (Hohhot, 8.5 %; Beijing, 21.6 %; and Shanghai, 23.5 %), NDVI (Hohhot, 0.31; Beijing, 0.33; and Shanghai, 0.39) were identified and related landscape strategies of cooling were proposed. The identification of ToCabs values can provide easy-to-use landscape recommendations to UHI mitigation.

The 2018–2019 UK residential dwellings clay shrinkage subsidence event

PurposeIn the UK, responses to intense weather events regarding national and regional level perils include the support of a General Insurance policy at the address level as part of private residential and other insurance policies covering the key risks of flooding, subsidence and windstorm. In respect of the subsidence peril, dry summers can lead to many thousands of properties on shrinkable clay soils suffering differential downward movement as water is abstracted from the soil by vegetation. These events are forecast to increase in frequency and severity due to climate change, with costs for a dry event year of more than £500m to UK insurers. Assessing the character of these event years can inform government, local government, insurers and their agents as to the typical characteristics of an event year and its impacts. The purpose of this paper is to provide a comprehensive overview of the 2018 UK subsidence event year as it relates to trees and low rise buildings.Design/methodology/approachThe research material is taken from claims that originated within the period commencing in the Summer of 2018, which in the UK was dry and with high levels of claim notification, and is from the private database of Property Risk Inspection Limited, one of the largest UK specialist subsidence claims handling businesses.FindingsThe data clearly illustrates the wide range of vegetative species causing or contributing to claims in the UK, their age ranges, sizes and conditions, management options and the range of land uses and statutory controls that exist in relation to title and other boundaries.Originality/valueThere have been various small-scale studies looking at individual cases of subsidence and the impacts of vegetation, but there have been no detailed investigations of large-scale claims-driven events such as the 2018 surge. The importance of this population-level investigation will only increase given the modelling for increased hot and dry summers over the coming decades.

Belskaya – a new variety of black currant

The climatic conditions of the Republic of Bashkortostan require the creation of varieties with high resistance to a complex of biotic and abiotic stressors of the region of cultivation. The data on economically valuable characteristics of a new variety of black currant Belskaya (breeding number 4-46) are presented. The black currant variety Belskaya was bred in the Republic of Bashkortostan in 1997 from pollination of the Valovaya (Krupnaya × Bredtorp × Khludovskaya) and Karaidel (Pamyati Michurina × Compactnaya). The year of sowing is 1998, the beginning of fruiting is 2002, the selection of an elite seedling is 2003, the transfer to the state varietal testing is 2013. The primary study of varietal samples was started in 2005 according to the planting scheme of 3 × 1 m. The control variety was Valovaya which is widespread and zoned across all regions of the Russian Federation. The Belskaya variety is characterized by high winter hardiness. There were no signs of freezing in severe winters, in the control variety Valovaya damage was noted up to 1 point with freezing of the tops of the annual growth. The leaf apparatus of the variety is resistant to sunburns. During the hot and dry summers (2010, 2011), it was distinguished by high drought resistance, while its productivity was higher than the control variety. The new variety is characterized by high productivity (yield on average 12.7 t / ha), and is resistant to shedding. It has fi resistance to American powdery mildew, weakly affected by anthracnose. Berries are one-dimensional, black, round‒oval shape, weighing 2.3 g (maximum 2.6 g), sweet and sour delicate taste. The maturation period is average. In 2022, the Belskaya variety was included in the State Register of Breeding Achievements of the Russian Federation in the Ural region.

Functional traits underlie specialist-generalist strategies in whitebark pine and limber pine

Plant species life history strategies are described by functional variation spanning an acquisitive and conservative resource use continuum. Specialist species can exhibit traits promoting one end of the continuum, while generalist species can display traits promoting both acquisitive and conservative resource use. Whitebark pine (Pinus albicaulis, PIAL) and limber pine (Pinus flexilis, PIFL) are two high-elevation pines that have similar growth and morphology, yet contrasting elevational distributions with PIAL viewed as a specialist inhabiting a narrower elevation range, and PIFL as a generalist inhabiting a broader elevation range. We compared the physiological and morphological traits of greenhouse-grown 5-year-old PIAL and PIFL. Our results suggest that PIFL’s acquisitive and conservative resource use traits contribute to its generalist strategy and ability to inhabit a greater range of elevations than PIAL. PIFL had greater acquisitive resource use traits including: high-light tolerance (greater Qsat, greater fascicle density), increased biomass allocation to photosynthetic tissue (higher needle biomass, aboveground:belowground biomass, needle:branch + stem biomass), and higher C and water uptake (greater stomatal density and size, higher C assimilation rate), as well as greater conservative resource use traits including: greater physical stress resistance (shorter height, higher stem and branch diameters, greater branch and stem diameter:length), drought tolerance (higher SWC, leaf starch proportion), and drought avoidance (earlier budburst phenology, smaller hydroscape area) than PIAL. Our results suggest that PIFL may make more efficient use of high-light loads and maximize C and water uptake when moisture is abundant during spring snowmelt before the onset of dry summer conditions. Other conservative resource use traits describing cold tolerance, heat tolerance, and drought tolerance did not differ between species, suggesting that both species exhibit traits that promote similar conservative resource use enabling their overlapping persistence at higher elevations. Comparing the physiology of PIAL and PIFL within the same environment enables us to identify physiological mechanisms that underlie species establishment and survival, and how juvenile physiology contributes to their contrasting distributions and their generalist-specialist strategies.

LAI‐based reduction in growth of semiarid grasslands and its responses to climate change on China's Loess Plateau

AbstractUnderstanding the response of vegetation growth to climate change can provide key information for predicting future ecosystem dynamics. Over the past 6 years, the semiarid regions of the Loess Plateau in China have experienced a transition from wet to dry years, but little is known about the response of grass growth to this change. Thus, this study aimed to analyze and evaluate the effect of climate change on grass growth. Using observed climate data and leaf area index (LAI) data obtained with hemispherical photography from 2016 to 2021, we investigated changes in trends of five climatic factors, including precipitation (P), temperature (T), relative humidity (RH), wind speed (WS), and solar radiation (Rs), and their impact on the growth of alfalfa (Medicago sativa) and Stipa bungeana plantations in the semiarid area of the Loess Plateau. The results showed a tendency to become colder in spring and drier in summer and autumn. In response, LAI tended to decrease in alfalfa and S. bungeana plots with interannual variation rates of 0.21 year−1 and 0.12 year−1, respectively. Additionally, linear regression methods showed that P had the greatest effect on LAI of two grasslands during the growing season (R2 &gt; 0.84, p &lt; 0.01), followed by RH and T (0.30 &lt; R2 &lt; 0.50, p &lt; 0.01), a negative effect of WS (R2 = 0.36, p &lt; 0.01), and no significant effect of Rs on LAI were found. Conversely, the path analysis indicated that Rs and P were the largest decision coefficients affecting the monthly LAI of alfalfa and S. bungeana, respectively, due to the different time‐to‐peak LAI and root growth depth of these two grass species. This study can provide theoretical support for ecological restoration and system management of semiarid grasslands.

Regeneration from seeds in a temperate native flora: A climate‐smart and natural–capital‐driven germination risk modelling approach

Societal Impact StatementExceptionally rainy winters and hot–dry summers are becoming the new normal around the United Kingdom. The effects of these climatic changes can already be seen in forests and grasslands, agricultural fields and even in our own gardens, as native plants try to keep pace with them. In this study, the seed germination of the native flora of Wakehurst, in the Southeast England, was analysed to identify potential threats to the long‐term persistence of selected species, which are part of the natural landscape of this area. Recommendations are provided for ecological restoration interventions which aim to maintain the different potential benefits those plants can provide to people.Summary Seeds play an important role in plant adaptation to human‐driven climate change. In this study, we applied a multilevel modelling of thermal germination responses of native temperate plants, to understand how global warming could affect their reproduction and the potential benefits they provide, as part of their natural capital. We identified Wakehurst (Southeast England, UK), as our study system. We modelled thermal seed germination parameters of the native flora as a whole and according to different uses categories (e.g., medicinal or food plants), through a phylogenetic meta‐analysis of publicly available data from Kew's Millennium Seed Bank (MSB). We also carried out a comparative germination study for MSB seed lots of 20 selected species. Finally, we quantified the germination risk, by comparing current and predicted environmental temperatures with thermal germination parameters at flora, uses categories and species level. Under future climatic scenarios, germination of the native flora will be at higher risk in spring than in autumn. Fitted quadratic models, although affected by phylogeny, did not show major differences among uses categories. Species with a narrow window of cold germination temperatures could be more at risk than those with warm optimal temperatures. Restoration activities should target species from phylogenetically clustered uses categories, to avoid losing their benefit provisions, and implement climate‐smart seed sourcing for high‐risk species. This multilevel germination modelling approach, based on collections and available data from conservation seed banks, can be applied to selected floras and regions to inform climate‐smart ecological restoration activities, while accounting for their natural capital.

Propagation and Characteristics of Hydrometeorological Drought Under Changing Climate in Irish Catchments

AbstractHydrometeorological droughts are complex hazards expressed through the relative deviation in water availability relative to long‐term average conditions. The development and propagation of drought is governed by hydrological processes at different spatial scales including precipitation, evapotranspiration, overland flow, soil moisture, groundwater storage and discharge. Detailed investigation is thus required to evaluate associated linkages among various types of hydrometeorological drought to understand the likely impacts of climate change on drought characteristics (magnitude, frequency, duration and propagation). This study explores the impact of climate change on hydrometeorological drought for 10 Irish catchments, using standardized drought indices representing different components of the hydrological system. We employ 12 Global Climate Models from the Coupled Model Inter‐comparison Project phase 6 (CMIP6), forced with SSP370 and bias corrected to catchment conditions to force a conceptual hydrological model to generate hydrological projections for each catchment. The results indicate substantial drying during summer with associated increases in summer drought magnitude and frequency. However, simulations show a wide range of change, especially for hydrological drought (discharge and baseflow). Only modest changes in the magnitude and frequency of hydrological drought events were found, with increases in winter and spring precipitation offsetting summer dryness. Similarly, the probability of meteorological drought propagating to hydrological events (Standardized Streamflow Index/Standardized Baseflow Index), shows modest increases under the climate change projections considered. Findings highlight that drought, especially during summer are a critical climate change risk for adaptation.

Urban Constructed Wetlands in Arid and Semiarid Zones

Abstract The development of societies and the increasing growth of recent constructions, especially in cities, have caused environmental issues, destruction, and reduction of natural resources and the environment, especially green and green-blue spaces. According to studies, in the past years, many parts of natural and even pristine surfaces and spaces in big cities have been turned into artificial, and impermeable spaces, which has aggravated environmental and ecological problems and also it has aggravated the aesthetic characteristics of the urban landscape, particularly in arid and semiarid areas. In this case, the studies show that identifying and applying natural ecosystems such as wetlands and their artificial types due to their multifunctional aspects and benefits, especially in urban areas, can be the basis for reducing many issues mentioned. Therefore, it is necessary to pay attention to this critical issue and do more research to know different types of constructed wetland ecosystems along with their services and values. The primary aim of this research is to identify the values and services of this ecosystem and to examine the diverse patterns of constructed wetlands in order to extract and design simple patterns of construcred wetlands. We want to know their role and position in landscape architecture and urban planning and design process. Also, this study aims to examine the potencial and possibillity of building constructed wetlands in urban areas particularly in arid areas and Mediterranean regions, according to Koppen climate classiffication. In this regard, the theoretical framework is provided based on the study of specialized texts and the study of similar foreign case studies and diverse patterns of urban wetlands with their different functions. These reviews have been done in a specific format consisting of some main aspects, such as the function and supply sources of wetlands. The final result and extractted simplified patterns, according to case studies, can be considered as a framework for designing and planning urban constructed wetlands and a guide for planning and designing a landscape consisting of this element, especially in areas with arid, semiarid, and Mediterranean climates with hot and dry summers.

Mediterranean service trees respond less to drought than oaks

Some widely distributed timber species, such as oaks, are vulnerable to low soil water availability and drought. Therefore, selecting broadleaved minor species with lower sensitivity to drought could be an alternative in seasonally dry areas. However, the growth performance of these minor hardwood species is unknown, particularly under warm and dry conditions at the southern limit of their distribution range. We assessed the radial growth response to drought by correlating tree-ring and climate data in coexisting service trees (Sorbus domestica) and two oak species (Quercus faginea, Quercus pyrenaica). Trees were sampled in three Mediterranean sites located in Spain with different precipitation patterns. We used the Vaganov–Shashkin (VS) growth model to infer the main climate constraints of growth. To ascertain whether climate is changing tree phenology, we also simulated changes in xylem onset and cessation timings and compared them with leaf falling dates in service trees. Service trees showed a trend towards advancing leaf fall, but this was not related to xylem growth. Oaks responded more to a drought index than service trees. The strongest responses corresponded to droughts peaking from spring to summer, but oaks tended to respond to longer droughts (9–13 months) than service trees (2–7 months). These different responses are due to the positive responses of all species to high precipitation in the growing season, but the sensitivity of oak growth to warm summer conditions and increased atmospheric water demand. The VS model indicated a more bimodal growth pattern in services trees than in oaks, which could allow the former to recover better after a dry summer. Service trees could be more widely used as a source of valuable timber wood under Mediterranean continental conditions.

The Eurasian shrew and vole tick Ixodes trianguliceps: geographical distribution, climate preference, and pathogens detected

The Eurasian shrew and vole tick Ixodes trianguliceps Birula lives in the nests and burrows of its small mammalian hosts and is—along with larvae and nymphs of Ixodes ricinus or Ixodes persulcatus—one of the most commonly collected tick species from these hosts in its Eurasian range. Ixodes trianguliceps is a proven vector of Babesia microti. In this study, up-to-date maps depicting the geographical distribution and the climate preference of I. trianguliceps are presented. A dataset was compiled, resulting in 1161 georeferenced locations in Eurasia. This data set covers the entire range of I. trianguliceps for the first time. The distribution area between 8^circ W–105^circ E and 40–69^circ N extends from Northern Spain to Western Siberia. To investigate the climate adaptation of I. trianguliceps, the georeferenced locations were superimposed on a high-resolution map of the Köppen–Geiger climate classification. The Köppen profile for I. trianguliceps, i.e., a frequency distribution of the tick occurrence under different climates, shows two peaks related to the following climates: warm temperate with precipitation all year round (Cfb), and boreal with warm or cold summers and precipitation all year round (Dfb, Dfc). Almost 97% of all known I. trianguliceps locations are related to these climates. Thus, I. trianguliceps prefers climates with warm or cold summers without dry periods. Cold winters do not limit the distribution of this nidicolous tick species, which has been recorded in the European Alps and the Caucasus Mountains up to altitudes of 2400 m. Conversely, I. trianguliceps does not occur in the Mediterranean area with its hot and dry summers.

The Increasing Role of Seasonal Rainfall in Western U.S. Summer Streamflow

AbstractSummer streamflow variations strongly affect water supply reliability and ecological functioning of western U.S. (WUS) streams. Traditional snow‐based forecasts of summer streamflow are becoming less accurate with warming‐induced reductions in winter snow accumulation. This reflects a rising importance of competing runoff‐generating processes in controlling summer streamflow variations, primarily an increasing role of rainfall in contrast to snowmelt. Here, based on a snowmelt‐rainfall tracking algorithm applied to two hydrological models, we show that cool‐season rainfall provides an important volumetric contribution to summer streamflow for many WUS streams in the current climate, and this contribution will increase under climate warming, especially in years with warm snow droughts and abnormally dry summers. We also show that seasonal rainfall (warm‐/cool‐seasons) dominates the variability of summer streamflow across ∼70% area of WUS. We show that an increasing warm‐season rainfall contribution to summer streamflow (largely replacing snowmelt) results in reduced summer streamflow predictability.

Selenium Removal by Sediments and Plants at the Constructed Pariette Wetlands, Utah (USA)

Selenium (Se) contamination of public lands and water is a result of irrigated agriculture and mining activities in areas rich in Se geologic deposits. Pariette Draw is part of the northern Colorado Plateau and is an area of concern for Se contamination in the Pariette Wetlands. Pariette Wetlands, a wetland built in the 1970s to provide wildlife habitat, is distinguished by its arid climate and a short growing season of hot dry summers followed by cold winters with several months below freezing. An understanding of how Se is mobilized and removed within the wetland will provide management strategies that minimize and mitigate Se contamination and promote sustainable ecosystem services. The data collected in 2012 and 2014 was the first comprehensive spatial and temporal analysis of Se in all environmental compartments (bird eggs, macroinvertebrates, plants, sediments, and water) of an arid wetland ecosystem in the Colorado Plateau. Water, sediment, and plant tissue samples were collected and analyzed to determine Se’s spatial and temporal variation in Pariette Wetlands. Se concentrations in water, sediment, and plants were evenly distributed throughout wetlands. No significant differences were found in plant Se concentrations between samples collected in 2012 (447 ± 44 ug kg−1) or 2014 (541 ± 42 μg kg−1), indicating that plant Se did not vary temporally during sampling. Aquatic plant species (e.g., pondweed (Potamogeton filiformis), 743 ± 66 μg kg−1 and watermilfoil (Myriophyllum spicatum), 874 ± 122 μg kg−1) accumulated more Se than plant species growing at the edges of the ponds (e.g., hardstem bulrush (Schoenoplectus acutus), 368 ± 37 μg kg−1 and cattail (Typha), 420 ± 43 μg kg−1). Plant roots (1045 ± 110 μg kg−1) accumulated more Se than aboveground vegetation (flowers, 228 ± 17 μg kg−1 or stems, 224 ± 19 μg kg−1). Relative to Se retained by sediments (75%), plants were not an extensive reservoir of wetland Se (&lt;5%) but still may pose a risk to animals feeding on plant tissue. Thus, phytoremediation of Se does not appear to be a viable tool for Se mitigation in wetlands of arid climates with a short growing season, such as those located in the Colorado Plateau.

Using Climatological Data to Identify Locations with Viticultural Potential in Colorado

Western Colorado’s warm, dry summers and access to mountain river water for irrigation create ideal conditions for the growth of wine grapes, specifically cultivars of the European grape species Vitis vinifera. The largest limiting factor to Vitis vinifera production is nocturnal temperatures cold enough to damage crops, or Low Temperature Injury Events (LTIEs). LTIEs require producers to undergo the time-and-cost prohibitive venture of retraining vines. Eastern Mesa County Colorado has sustained large-scale grape production due to the area’s relatively mild cold season weather. Areas with similarly hospitable conditions may exist elsewhere within western Colorado. Parametrized Regression on Independent Slopes Model (PRISM) temperatures (1981-2020) were used to estimate the frequency of LTIEs across Colorado, and identify trends associated with a warming climate. In the interest of comparing PRISM temperatures to observations over actual vineyards, thermometers were placed on current vineyards in Montezuma County from 2016 to 2020. Findings suggest additional areas of opportunity for Vitis vinifera production exist in Colorado, particularly western Montezuma County, and western Mesa and Montrose Counties. Like eastern Mesa County, these areas experience a LTIE in fewer than 20 % of years. PRISM data also suggest southeast Colorado is becoming more hospitable for Vitis vinifera growth over time. Temperature measurements in Montezuma County during potentially lethal weather events compared closely with PRISM data, with a mean absolute difference of 1.8 ˚C. This comparison suggests PRISM is a reliable tool for identifying areas of opportunity in spite of western Colorado’s complex terrain.

Vitality loss of beech: a serious threat to Fagus sylvatica in Germany in the context of global warming

In the light of ongoing climate change, European beech trees face a loss of vitality due to an expected increase in the frequency of droughts, exacerbated by prolonged periods of high temperatures and solar radiation. Such conditions increase the predisposition to European beech splendour beetle attacks, and trigger sunburn, fungal infections and complex diseases. As a result, European beech forests are seriously threatened by climate change. Following prolonged and repeated periods of exceptional drought since 2018, European beech decline have been observed in several regions of Germany and Europe. Vitality losses, in some cases severe, of due to the extraordinarily warm, dry summers of 2018 and 2019 have been observed and investigated in several regions of Germany. The first symptoms of vitality loss of European beech associated with severe signs of crown dieback were recorded in midsummer 2018. Mortality of branches and individual trees was often associated with sunburn, bark necrosis and bleeding spots of sap flux. The first signs of mortality were observed locally in predisposed stands in autumn 2018. The stem stability and break resistance of affected trees were significantly reduced. To elucidate the complex interactions involved, the occurrence of vitality loss of European beech and associated causative agents were examined in north-western Germany. Disease symptoms of individual trees were studied, associated fungi (endophytes, plant pathogens and saprobes) were isolated and identified. Frequent potentially severe pathogens included Neonectria coccinea, Diplodia corticola and D. mutila. The presented cases of disease were the first, where D. corticola was recorded on beech. In addition, inoculation tests were used to assess the potential roles of Botryosphaeria species in the observed symptomatology.

Climate change-induced aridity is affecting agriculture in Northeast Italy

CONTEXTThe Mediterranean basin and specifically Northeast Italy are recognised as climate change hotspots. The latter is a key socio-economic area in Europe among the most agriculturally productive. However, increasingly frequent drought periods (typical of drier climates) are threatening agriculture. An extreme event occurred in the summer of 2022. It dramatically affected northern Italy, through high temperatures, water shortages and indirect processes (such as saltwater intrusion in the Po River Delta). OBJECTIVEThe objective is to map and quantify the agricultural areas in Northeast Italy at risk of climate zone shift due to human-induced climate change, providing a comprehensive overview of the main threatened agricultural systems and supporting the use of projections through historical data analysis. METHODSWe compared the distribution of current (1980 > 2016) and future (2071 > 2100; RCP8.5 scenario) climate zones for 8 main agricultural systems in 14 key provinces in Northeast Italy. Further analyses were performed on historical data to support future climate projections and to analyse agricultural drought during extreme events: (1) a multi-temporal Aridity Index (AI) to investigate aridification dynamics; (2) a focus on the 2022 event (drought and temperature extremes, a situation that is likely to occur more often in the future), combining a Vegetation Health Index (VHI) with a zonal investigation of high Land Surface Temperature (LST); (3) a climate focus for the Po River Delta cultural landscape. RESULTS AND CONCLUSIONSThe results show that the climate in Northeast Italy is evolving towards drier conditions, posing a challenge to agriculture. The Adriatic coast could become an Arid zone, a finding in line with historical observations. Rice fields will be most at risk (76% of their surface could become Arid in the future), as well as the irrigated lands that are essential for food security (around 20% expected in the Arid zone). Worthy is what is foreseen for crops on slopes (often not irrigated), which may experience drier summers (60% of the surface). SIGNIFICANCEWe identified the areas at risk of climate change at the farm scale in Northeast Italy, mapping where the threatened fields are located, what their extent is, and which agricultural systems are currently implemented. Such information would facilitate early action, guiding large-scale planning towards more resilient agriculture. Findings could promote sustainable water management plans, open the debate on which crops are worth growing based on future climate, and inspire more localised studies in the design of mitigation measures.

Investigation on application of plate-tube evaporative condensating technology for data centres in the northwest of China

The rapid development of data center leads to a rapid increase in energy consumption. In this paper, the plate and tube evaporative condenser is proposed for the water-cooled chiller and the data center cooling system to improve the energy efficiency in hot and dry summer and avoid icing in cold winter. The chiller can operate in the wet mode for compressor refrigeration and the dry mode for free cooling with the coefficient of performance (COP) of 5.2 in wet mode and up to 33.3 in dry mode. Furthermore, the system is applied in a data center in Ulumiqi, which is located in the dry and cold region and its ambient air temperature can vary from −32 °C to 45 °C throughout the year. The actual operation results show that the power usage effectiveness (PUE) value of the whole data centre is 1.349 in June, 1.229 in December, and 1.320 as the annual average, which is stable and efficient for five consecutive years. These results ensure the proposed system is an important technical solution for energy saving and emission reduction in data centres in cold regions.

Understanding and Reducing Warm and Dry Summer Biases in the Central United States: Analytical Modeling to Identify the Mechanisms for CMIP Ensemble Error Spread

Abstract Most climate models in phase 6 of the Coupled Model Intercomparison Project (CMIP6) still suffer pronounced warm and dry summer biases in the central United States (CUS), even in high-resolution simulations. We found that the cloud base definition in the cumulus parameterization was the dominant factor determining the spread of the biases among models and those defining cloud base at the lifting condensation level (LCL) performed the best. To identify the underlying mechanisms, we developed a physically based analytical bias model (ABM) to capture the key feedback processes of land–atmosphere coupling. The ABM has significant explanatory power, capturing 80% variance of temperature and precipitation biases among all models. Our ABM analysis via counterfactual experiments indicated that the biases are attributed mostly by surface downwelling longwave radiation errors and second by surface net shortwave radiation errors, with the former 2–5 times larger. The effective radiative forcing from these two errors as weighted by their relative contributions induces runaway temperature and precipitation feedbacks, which collaborate to cause CUS summer warm and dry biases. The LCL cumulus reduces the biases through two key mechanisms: it produces more clouds and less precipitable water, which reduce radiative energy input for both surface heating and evapotranspiration to cause a cooler and wetter soil; it produces more rainfall and wetter soil conditions, which suppress the positive evapotranspiration–precipitation feedback to damp the warm and dry bias coupling. Most models using non-LCL schemes underestimate both precipitation and cloud amounts, which amplify the positive feedback to cause significant biases.

Hardwoods influence effect of climate and intraspecific competition on growth of woodland longleaf pine trees

AbstractLongleaf pine woodlands of the North American Coastal Plain are proposed to be resilient to climate change impacts, but little is known about changes in limiting factors to longleaf pine growth as climate has changed in late 20th century and early 21st century. Moreover, the role that neighborhood trees play in the context of climate change remains largely unexplored. We used static and moving window tree ring and climatic analyses to measure the effects of climate on longleaf pine growth at a site in southwest Georgia, USA. We then performed maximum likelihood analysis to examine the influence of neighboring hardwoods on the response of longleaf pine growth to the joint effects of competition and climate. Analysis of climate data from local stations in southwest Georgia over six decades indicated that mean air temperature decreased until the late 20th century then began to rise, and that the variability of spring and summer precipitation has increased. Tree ring and climate analyses indicated longleaf pine radial growth is sensitive to precipitation and air temperature, and that the strength of correlation of longleaf pine growth to summer air temperature and summer precipitation increased since the 1950s. Likelihood models, which were applied over a shorter (23‐year) period and explicitly incorporated competition, did not support a link between summer temperature and growth but did indicate summer precipitation increased growth. Furthermore, basal area (BA) of neighboring hardwoods was correlated with greater pine growth per millimeter of precipitation. BA of neighboring longleaf pine negatively affected growth of conspecific trees; the presence of hardwoods increased the competitive effect when BA of neighboring pine trees was low (&lt;10 m2 ha−1) but decreased the competitive effect when BA of neighboring pine trees was high (≥10 m2 ha−1). These results suggest that retention or recruitment of hardwood trees when restoring longleaf pine woodlands may contribute to increased ability to withstand dry summers and may help to allay concerns of managers that retention of hardwoods will unduly affect growth of residual mature longleaf pines.

Understanding and Reducing Warm and Dry Summer Biases in the Central United States: Improving Cumulus Parameterization

Abstract Most climate models still suffer large warm and dry summer biases in the central United States (CUS). As a solution, we improved cumulus parameterization to represent 1) the lifting effect of small-scale rising motions associated with Great Plains low-level jets and midtropospheric perturbations by defining the cloud base at the level of condensation, 2) the constraint of the cumulus entrainment rate depending on the boundary layer depth, and 3) the temperature-dependent cloud-to-rainwater conversion rate. These improvements acted to (i) trigger mesoscale convective systems in unfavorable environmental conditions to enhance total rainfall amount, (ii) lower cloud base and increase cloud depth to increase low-level clouds and reduce surface shortwave radiation, (iii) suppress penetrative cumuli from shallow boundary layers to remedy the overestimation of precipitation frequency, and (iv) increase water detrainment to form sufficient cirrus clouds and balanced outgoing longwave radiation. Much of these effects were nonlocal and nonlinear, where more frequent but weaker convective rainfall led to stronger (and sometimes more frequent) large-scale precipitation remotely. Together, they produced consistently heavier precipitation and colder temperature with a realistic atmospheric energy balance, essentially eliminating the CUS warm and dry biases through robust physical mechanisms.

Rodent population dynamics and crop loss estimation due to rodent pests in finger millet based crop lands

Ragi (Eleusine coracana Gaertn ) also known as finger millet is an important millet widely grown in Asia and is the major staple food in southern Karnataka. Rodents are critical vertebrate pests and are regarded as big chaos to agricultural production. In the present studies the rodent population and crop loss due to rodent pest in finger millet crop was analyzed during the year 2022. The studies revealed that with mean trap index of 20.28 the rodent activity in the finger millet crop lands was observed throughout the year and the peak rodent activity was recorded in Kharif and Rabi crop seasons and was less in the dry (summer) seasons. The population was male and adult dominant with a male female ratio of 1:0.92 and adult infant ratio of 1:0.56, respectively. The Shannon index (Hǀ) in finger millet crop lands found to be 1.08 and the peak Shannon index was recorded in the month of August with a highest relative abundance of Bandicota bengalensis, Tatera indica and Mus platythrix rodent species in the finger millet crop lands. The yield loss estimation studies indicated that there was a grain loss of 2.98 q ha-1 in finger millet crop lands with a monetary value of Rs. 10, 662 (US $129.48) per hectare.