Changes In Water Availability Research Articles

Lethal combination for seedlings: extreme heat drives mortality of drought-exposed high-elevation pine seedlings.

Hotter drought- and biotically-driven tree mortality are expected to increase with climate change in much of the western United States, and species persistence will depend upon ongoing establishment under novel conditions or migration to track ecological niche requirements. High-elevation tree species may be particularly vulnerable to increasing water stress as snowpack declines, increasing the potential for adult mortality and simultaneous regeneration failures. Seedling survival will be determined by ecophysiological limitations in response to changing water availability and temperature. We exposed seedlings from populations of Pinus longaeva, Pinus flexilis, and Pinus albicaulis to severe drought and concurrent temperature stress in common gardens testing timing of drought onset under two different temperature regimes. We monitored seedling functional traits, physiological function, and survival. The combined stressors of water limitation and extreme heat led to conservative water use strategies and declines in physiological function, with these joint stressors ultimately exceeding species' tolerances and leading to complete episodic mortality across all species. Growing conditions were the primary determinant of seedling trait expression, with seedlings exhibiting more drought-resistant traits such as lower specific leaf area in the hottest, driest treatment conditions. Water stress-induced stomatal closure was also widely apparent. Under adequate soil moisture, seedlings endured prolonged exposure to high air and surface temperatures, suggesting broad margins for survival. The critical interaction between soil moisture and temperature suggests that rising temperatures will exacerbate growing season moisture stress. Our results highlight the importance of local conditions over population- and species-level influences in shaping strategies for stress tolerance and resistance to desiccation at this early life stage. By quantifying some of the physiological consequences of drought and heat that lead to seedling mortality, we can better understand the future effects of global change on the composition and distribution of high-elevation conifer forests.

Altai Mountains – cradle of hybrids and introgressants: A case study in Veronica subg. Pseudolysimachium (Plantaginaceae)

AbstractMountains form a diverse mosaic of microhabitats over small distances created by changes in climate, soil, and water availability. A key to adaptation of plants to such microhabitats is genetic variation; however, natural accumulation of genetic variation through mutation is slow and often not sufficient alone. Adaptive introgression via hybridization is an alternative to generate genetic variation. Here, we investigate hybridization and discuss its adaptive role in Veronica subg. Pseudolysimachium at their Altai Mountains distribution. To support our hypotheses of frequent hybridization, we genotyped thousands of SNPs for 233 individuals from 10 species and 7 putative hybrids previously described based on morphology. We employed Bayesian and likelihood statistical models and supported our results by morphometric analysis and genomic in situ hybridization (GISH). The results suggest that almost all the individuals of the putative hybrids are of F1 type. The GISH investigation in one case strongly supports homoploid hybridization (origin of V. ×schmakovii from V. longifolia and V. porphyriana. Divergence times of Altai Veronica species are estimated to be within 1–2 million years ago with high probability of gene flow over that time. Our results also demonstrate that the direction of gene flow is mainly from the locally endemic V. porphyriana. We hypothesize that the large Siberian plains and topographically diverse foreland of the Altai Mountains provide an ideal setting for hybridization with the potential for adaptive introgression of alleles conferring tolerance to cooler climates, to the lowland species migrating into the Altai Mountains.

Learning from local knowledge on changes in tree-cover and water availability: the case of the contested agroforested landscape of the Mt. Elgon Water Tower, Uganda

Participatory Rural Appraisal was used to compare stakeholder perceptions of spatial and temporal variation in tree cover and water availability using Uganda’s Mt. Elgon Water Tower as a case study. This study was guided by the research question: How do multi-level stakeholders’ perceptions of changes in tree-cover and water availability vary across spatial and temporal scales of the water tower? Five Participatory Rural Appraisal tools were applied to understand multi-level stakeholders’ perspectives on the changes in tree-cover and water availability. Data was collected from farmers’ focus group discussions, key experts from local government offices and structured household interviews with local communities. This study focused on the upper and lower zones of the water tower, which differ in terms of proximity to Mt. Elgon National Forest Park, household water-use, elevation, and tree-cover. Results showed that there are both similarities and differences in perceptions of changes in tree cover and water availability among stakeholders. Farmers and key experts perceived a decrease in water availability and a decrease in overall tree cover for the period 1990–2020. There are differences in stakeholders’ perceptions of water availability across the zones and sub-catchments. For instance, more farmers in Sipi River Sub-catchment perceived a decrease in water availability during 2006–2020 compared to 1990–2005 period. There were notable contradictions in farmers’ and key experts’ perceptions on tree cover. Farmers’ perceptions of 1990–2020 precipitation were in agreement with trends in existing precipitation data. Declining trends of natural tree cover especially outside the Mt. Elgon national forest park pose great threat to water resources originating from forests. Changes in tree cover and water availability in the study area can be partly explained by the tree species grown. Local stakeholders’ perceptions complemented the existing data gaps in explaining the changes in tree cover and water availability. Participatory Rural Appraisal tools are helpful for documenting the perceptions of local communities. However, this cannot replace reliable data resulting from large-scale efforts for monitoring changes and variations in tree-cover and water availability. The findings of this paper can be valuable to inform strategies for community involvement in sustainable agroforested landscape management.

Does lower water availability limit stem CO2 efflux of oak and hornbeam coppices?

Recent changes in water availability can be crucial for the development, growth and carbon budget of forests. Therefore, our aim was to determine the effect of reduced throughfall and severe summer drought on stem CO2 efflux as a function of temperature and stem increment. Stem CO2 efflux was measured using the chamber method on oak and hornbeam under four treatments: coppice, thinned coppice, and both coppice and thinned coppice with 30 %-reduced throughfall. The first year of the experiment had favourable soil water availability and the second year was characterized by a dry summer. While reduced throughfall had no effect on stem CO2 efflux, the summer drought decreased efflux by 43-81 % during July and August. The stem CO2 efflux was reduced less severely (by 13-40 %) in September when the drought persisted but the stem increment was already negligible. The stem increment was also strongly affected by the drought, which was reflected in its paired relationship with stem CO2 efflux over the two experimental years. The study showed that summer dry periods significantly and rapidly reduce stem CO2 efflux, whereas a constant 30 % rainfall reduction needs probably a longer time to affect stem properties, and indirectly stem CO2 efflux.

A Study of Impact of Climate Change on Livelihood of Farmers in Kumaon Himalaya

Climate change in the Kumaon Himalaya can significantly affect farmers in various ways. Shifts in temperature and precipitation patterns may impact crop yields, disrupt traditional farming practices, and lead to increased vulnerability. Changes in water availability and the melting of glaciers can affect irrigation, essential for agriculture in the region. Additionally, the altered climate may influence the prevalence of pests and diseases, posing further challenges to crop production. Overall, adapting to these changes is crucial for sustaining agricultural livelihoods in the Kumaun Himalaya. The present study is based on both primary and secondary data survey to highlight the impact on farmers livelihood pattern in the study area.

Hydro-meteorological response to climate change impact in Ethiopia: a review

Abstract Climate change poses significant challenges to water resources and streamflow in Ethiopia, a country highly dependent on agriculture and vulnerable to environmental shifts. This paper reviews the current state of knowledge on climate change impacts on streamflow in Ethiopia, emphasizing factors driving these changes and drawing insights from relevant studies. The analysis encompasses hydrological responses to climate change, including alterations in precipitation patterns, temperature fluctuations, and changes in water availability. Additionally, the study examines the impact of land use changes on streamflow dynamics. Comparative insights from neighboring countries and river basins further illuminate the broader regional implications of climate change on water resources. According to the previous research reviewed in this paper, climate change, land use change, and increment in extreme events (drought) have affected the stream flow over the last decades. The findings underscore the urgent need for adaptive strategies and sustainable water management practices to mitigate the adverse effects of climate change on streamflow and ensure water security in Ethiopia and beyond.

A temporal analysis of the consequences of the drought regime on the water footprint of agriculture in the Guadalupe Valley, Mexico

Changes in water availability have a substantial impact on the sustainability and maintenance of agriculture, with water footprint (WF) being a robust methodology to assess these transformations. The Guadalupe Valley is one of the places with the highest agricultural production in Mexico. Despite its semi-arid climatic conditions, it provides high-quality crops that are well-positioned in the world. The historical trend of rainfall and temperatures between 1987 and 2017 was analyzed to identify climatic patterns in the territory. Through the calculations of the water footprint of Grapevine and Olive crops, the sensitivity of the crops to recurrent water deficit and their adaptation in their yields to drought episodes was identified. The reduction in precipitation and occurrence of extreme temperatures have contributed significantly towards augmenting crop evapotranspiration and, consequently, intensifying crop irrigation demands. As a result, there has been an apparent increase in the consumption of WFagricultural since 2007. Thus, the period of highest WFagricultural consumption was 2014 (Extremely dry), as opposed to 2011 (Very wet). In particular, the lowest WFgreen consumptions were observed in extremely dry years, that is, > 20% of the WFagricultural intensifying drought events. Therefore, these periods were compensated with higher uses of WFblue and WFgray, which are inversely correlated with precipitation, where vine crops consume 73% more WFagricultural compared to olive plantations, showing greater interannual variability. These results contribute to analyzing the temporal evolution of water consumption for agriculture, providing a basis for rational water use strategies.

Single-cell transcriptomics reveal heterogeneity in plant responses to the environment: a focus on biotic and abiotic interactions.

Environmental cues, from biotic or abiotic origin, are major factors influencing plant growth and productivity. Interactions with biotic (e.g. symbionts and pathogens) and abiotic (e.g. changes in temperature, water or nutrient availability) factors trigger signaling and downstream transcriptome changes in plants. While bulk RNA-sequencing technologies have traditionally been used to profile these transcriptional changes, the heterogeneity of the responses, caused by the cellular complexity of organs, might be masked by homogenizing tissues. Thus, whether different cell types respond equally to environmental fluctuations, or whether subsets of the responses are cell-type specific, are long-lasting questions in plant biology. The recent break-through of single-cell transcriptomics in plant research offers an unprecedented view on cellular responses under changing environmental conditions. In this review, we discuss the contributions of single-cell transcriptomics towards the understanding of cell-type specific plant responses to biotic and abiotic environmental interactions. Besides major biological findings, we present some technical challenges coupled to single-cell studies of plant-environment interactions, proposing possible solutions and exciting paths for future research.

Envisioning Transition from Open Landscapes to Forested Landscapes in the Routt National Forest, Colorado, United States

Globally, in remaining wildlands, tree densities and forested cover have increased in grasslands and open forests since European settlement. In the southern Rocky Mountains of Colorado, United States, we determined tree composition and tree cover from historical (years 1875 to 1896) surveys and compared them to current (2002 to 2011) tree composition and current (year 2016) forested land cover for 500,000 ha of the Routt National Forest. Additionally, we examined whether changes in precipitation occurred. Regarding composition, pine (primarily lodgepole pine; Pinus contorta) decreased from 65% to 32% of all trees, with increased subalpine fir (Abies lasiocarpa) from 0.5% to 23% of all trees, and quaking aspen (Populus tremuloides) from 13% to 30% of all trees. According to 80% of 5175 survey points not in forests, the historical landscape was very open, comprised of grasslands, mountain meadows, and other open ecosystems. In contrast, 75% of the current landscape is covered by forests. Change points in the Palmer Modified Drought Index were within historical limits, indicating that forestation was not related to a change in water availability. Based on historical surveys and accounts, we envisioned a historical landscape that was open but embedded with dense lodgepole pine clusters and spruce stands at high elevations, which has now become a predominantly forested landscape of dense forests, similar to global forestation patterns.

Drought influences habitat associations and abundances of birds in California's Central Valley

AbstractAimAs climate change increases the frequency and severity of droughts in many regions, conservation during drought is becoming a major challenge for ecologists. Droughts are multidimensional climate events whose impacts may be moderated by changes in temperature, water availability or food availability, or some combination of these. Simultaneously, other stressors such as extensive anthropogenic landscape modification may synergize with drought. Useful observational models for guiding conservation decision‐making during drought require multidimensional, dynamic representations to disentangle possible drought impacts, and consequently, they will require large, highly resolved data sets. In this paper, we develop a two‐stage predictive framework for assessing how drought impacts vary with species, habitats and climate pathways.LocationCentral Valley, California, USA.MethodsWe used a two‐stage counterfactual analysis combining predictive linear mixed models and N‐mixture models to characterize the multidimensional impacts of drought on 66 bird species. We analysed counts from the eBird participatory science data set between 2010 and 2019 and produced species‐ and habitat‐specific estimates of the impact of drought on relative abundance.ResultsWe found that while fewer than a quarter (16/66) of species experienced abundance declines during drought, nearly half of all species (27/66) changed their habitat associations during drought. Among species that shifted their habitat associations, the use of natural habitats declined during drought while use of developed habitat and perennial agricultural habitat increased.Main ConclusionsOur findings suggest that birds take advantage of agricultural and developed land with artificial irrigation and heat‐buffering microhabitat structure, such as in orchards or parks, to buffer drought impacts. A working lands approach that promotes biodiversity and mitigates stressors across a human‐induced water gradient will be critical for conserving birds during drought.

Changing agricultural practices as a result of variable water resource availability in a hilly area of An Giang province, Vietnam

Abstract Located in the Southwest of the Mekong Delta in Vietnam, An Giang province is an important center of agricultural production, especially rice cultivation. Climate change impacts are one of several man-made factors affecting water resource availability for agriculture in the province. It is recognized that new solutions are crucial to adapt to the present and future conditions of a scarcer water supply. This paper explores climate factors affecting water resource availability in agriculture and some recent adaptations being adopted by farmers in one district of An Giang province. Hydro-meteorological data was collected together with in-depth interviews as a tool to point to proximate changes in water status and availability and to evaluate local inhabitants’ awareness of climate risks and adaptive strategies. The results noted that climate factors (temperature, humidity, annual rainfall) have altered over time, causing decreased availability of water supplies for agriculture. Recognizing this situation, both structural adaptation and non-structural solutions may occur simultaneously to maintain agricultural production efficiency. The types of crops, tolerant varieties, and irrigation projects suitable for various geographical areas were considered for more adaptive agriculture production locally. To address some of the problems that farmers face, water-saving technologies are an essential part of a range of potential solutions to maintain agricultural production and protect the environment in the future.

Save or spend? Diverging water‐use strategies of grasses and encroaching clonal shrubs

Abstract Shrub encroachment is one of the primary threats to mesic grasslands around the world. This dramatic shift in plant cover has the potential to alter ecosystem‐scale water budgets and responses to novel rainfall regimes. Understanding divergent water‐use strategies among encroaching shrubs and the grasses they replace is critical for predicting shifts in ecosystem‐scale water dynamics as a result of shrub encroachment, particularly if drought events become more frequent and/or severe in the future. In this study, we assessed how water‐use traits of a rapidly encroaching clonal shrub (Cornus drummondii) and a dominant C4 grass (Andropogon gerardii) impact responses to changes in water availability in tallgrass prairie. We assessed intra‐annual change in depth of water uptake, turgor loss point and stomatal regulation in each species. Sampling took place at Konza Prairie Biological Station (northeastern KS, USA) during the 2021 and 2022 growing seasons. Cornus drummondii shifted from shallow to deep soil water sources across the 2021 and 2022 growing seasons. This plasticity in depth of water uptake facilitated a ‘wasteful’ water‐use strategy in C. drummondii, where stomatal conductance and transpiration rates continued to increase even when no further gain in photosynthetic rate occurred. A. gerardii photosynthetic rates and stomatal conductance were more variable through time and were more responsive to changes in leaf water potential than C. drummondii. However, intra‐annual adjustment of turgor loss point was more pronounced in C. drummondii (ΔπTLP = −0.48 MPa ± 0.15 SD) than in A. gerardii (ΔπTLP = −0.29 MPa ± 0.19 SD). Synthesis. These results suggest that C. drummondii is highly resilient to changes in water availability in surface soils and will likely remain unaffected by future droughts unless they are severe enough to reduce the availability of deep soil water. Given that clonal shrubs are key invaders of grasslands world‐wide, increased leaf‐level water loss is expected to accelerate ecosystem‐level drying as clonal shrub encroachment proceeds in mesic grasslands.

Evaluating future water availability in Texas through the lens of a data-driven approach leveraged with CMIP6 general circulation models

Climate change is escalating the frequency and intensity of extreme precipitation events, significantly influencing the spatial and temporal distributions of water resources. This is particularly evident in Texas, a rapidly growing state with a pronounced west-east gradient in water supply. This study utilizes Coupled Model Intercomparison Project Phase 6 (CMIP6) data and data-driven methodology to improve projections of Texas's future water resources, focusing on actual evapotranspiration (AET) and water availability through enhanced Multi-Model Ensembles. The results reveal that the data-driven model significantly outperforms the CMIP5 and CMIP6 models across all skill metrics, underscoring the potential of data-driven methodologies in advancing climate science. Furthermore, the study provides an in-depth analysis of the projected changes in net water availability (NWA) and estimated water demand for different regions in Texas over the next six decades from 2015 to 2074, which reveal fluctuating patterns of water stress, with the regions (nine out of sixteen water planning regions in Texas, especially for the most populated regions) poised for heightened challenges in reconciling water demand and availability. While increasing trends are found in precipitation, AET, and NWA for the northern region of Texas based on SSP2–4.5, decreasing trends are found over the southern region for all three parameters based on SSP5–8.5. These findings underscore the importance of factoring both spatial and temporal variations in water availability and demand for effective water management strategies and the need for adaptive water management strategies for the changing water availability scenarios.

Does ERA5-land capture the changes in the terrestrial hydrological cycle across the globe?

Changes in the terrestrial hydrological cycle determine the future water availability across the globe with profound impacts in different facets of society. Precise estimation of such changes is vital for the effective implementation of water management policies. Among the numerous data products that describe the hydrological cycle components, ERA5-Land is one of the most increasingly used dataset. Still, there has been no assessment of its ability capacity to represent the water cycle shifts variability over land. This study endeavors to bridge this gap by comparing the magnitude and direction of change in precipitation minus evaporation (P—E) and runoff, as estimated globally by the ERA5-Land data product. Our findings reveal significant inconsistencies in the changes identified, with the climatological mean of P—E decreasing more substantially than runoff for numerous regions. Consequently, ERA5 presents a declining water availability for most of the regions, but the magnitude of change is incompatible to the change between P—E and runoff. To further validate, the estimates provided by the ERA5-Land product, two different hydrologic models (TerraClimate and Global Land Data Assimilation System, GLDAS-Noah) are also utilized. TerraClimate demonstrates a more reasonable alignment between changes in P—E and runoff, followed by GLDAS-Noah, particularly for the arid regions lying in the parts of Northern Africa and Southern Asia, the European continent, and the northern parts of Asia. Inconsistencies remain high for the tropical regions for both data products. Still, the estimates of change in water availability are better represented by the hydrologic model-based data sources for most parts of the globe, especially for the regions with low precipitation, such as the regions with arid and continental climates. Our results imply that ERA5-Land should be used with extreme caution when assessing the long-term changes in the terrestrial water cycle. Additionally, pinpointing the regions of the highest bias can help to improve the hydrological coupling of ERA5-Land in future versions of the reanalysis.

Using phenology to unravel differential soil water use and productivity in a semiarid savanna

AbstractSavannas are water‐limited ecosystems characterized by two dominant plant types: trees and an understory primarily made up grass. Different phenology and root structures of these plant types complicate how savanna primary productivity responds to changes in water availability. We tested the hypothesis that productivity in savannas is controlled by the temporal and vertical distribution of soil water content (SWC) and differences in growing season length of understory and tree plant functional types. To quantify the relationship between tree, understory, and savanna‐wide phenology and productivity, we used PhenoCam and satellite observations surrounding an eddy covariance tower at a semiarid savanna site in Arizona, USA. We distinguished between SWC across two different depth intervals (shallow, <0–30 cm and deep, >30–100 cm). We found that tree greenness increased with SWC at both depths, while understory greenness was only sensitive to the shallower SWC measurements. Onset of ecosystem dormancy, estimated from satellite observations close to the eddy covariance tower, explained more variability in annual gross primary productivity (GPP) than in other phenometrics. Higher SWC led to an extended growing season, caused by delayed dormancy in trees, but the understory showed no evidence of delayed dormancy in wetter periods. We infer that the timing of ecosystem scale dormancy, driven by trees, is important in understanding changes in a savanna's GPP. These findings highlight the important effects of rainfall during the winter. These findings suggest that savanna GPP is conditional on different responses to moisture availability in each of the dominant vegetation components.

Influence of short-term, water-deprived bermudagrass on Orius insidiosus predation and Spodoptera frugiperda larval survival and development

ABSTRACT Turfgrass is susceptible to changes in water availability, and its effects could cascade through multiple trophic levels. In some years, turfgrass is exposed to short drought spells. It is unclear if this short period of water deprivation would cascade to predator performance on herbivory on bermudagrass. Thus, the objective of this study was to determine the effects of water deprivation on predation by Orius insidiosus (Say) (Hemiptera: Anthocoridae) on Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae) when mediated by drought-tolerant ‘TifTuf’ and drought-susceptible ‘Tifway’ bermudagrass. Neonates of S. frugiperda and adults of O. insidiosus were caged on bermudagrass in greenhouse conditions. Treatments were three factors: 1) water deprivation at three levels – fully, moderately, and sparsely watered; 2) predator at two levels – present or absent; and 3) bermudagrass at two levels – drought tolerant and susceptible cultivars. The survival of S. frugiperda larvae was reduced when O. insidiosus adults were present regardless of water deprivation levels and bermudagrass cultivars. Reduced larval weight, body length, and head capsule width of S. frugiperda larvae were observed with predators compared to without predators. S. frugiperda larval mortality was significantly greater with predator’s absence for the sparsely-watered treatment than for the fully and moderately-watered treatments. The levels of water deprivation had a partial impact on the survival of S. frugiperda larvae, whereas bermudagrass cultivars did not affect the survival and development of S. frugiperda larvae. Thus, during at least short-term dry spells, O. insidiosus predation can potentially reduce the S. frugiperda population on bermudagrass.

Great Salt Lake desert landscape change over multiple temporal scales

This one-day (~260-mile) field trip guide provides an overview of the late Pleistocene to Holocene history of the Great Salt Lake Desert. Stops include Knolls Sand Dunes and areas on or surrounding the Bonneville Salt Flats, such as Juke Box trench, the Bonneville Salt Flats International Speedway, and the saline pan center and edge (Figure 1). We cover the post-Lake Bonneville geomorphic evolution of the Great Salt Lake Desert including changes in land cover over the past century. The Great Salt Lake Desert area provides unique access to saline landscape features including gypsum dunes and a perennial saline pan. We discuss the origin of these features and how they fit within the area’s broader geologic context. The accessibility of sites discussed here depends on surface conditions. In general, late summer to early fall is the most opportune time to visit this area. Vehicular travel to any of the off-road sites is discouraged when there is standing water or high near-surface moisture (wet mud with little traction). Surface conditions can change rapidly, and we recommend researching current conditions before initiating this trip. This desert is hot and dry during the summer and there is no shade and limited access to water; please plan accordingly. Past and current Great Salt Lake Desert depositional changes provide an analog for the modern Great Salt Lake with changing water availability, potential dust production, competing priorities, and rapidly changing land cover. The information presented here impacts understanding natural and geologic heritage, changing management strategies, and landscape dynamism over multiple spatial and temporal scales.

Bonneville basin critical zones

Playa margin wetlands in the Bonneville basin are sustained by groundwater-fed brackish springs, which transport salts and other solutes into the playa basin. These wetlands are sensitive to changing water availability and quality, which are impacted by changing climate and land use, and whose sediments also provide important records of changing environmental conditions. Gastropods building their shells in these springs provide important recorders of water chemistry and may reflect changing aqueous conditions. In this paper, we analyze spring water chemistry, gastropod ecology and gastropod shell chemistry of Blue Lake (BL) and Horseshoe Springs (HRS), two groundwater-fed wetlands in the Great Salt Lake watershed. We report the physical parameters including pH, temperature, and specific conductivity across the spring pond at Horseshoe springs. There was a slight but statistically significant variation in these physical characteristics between the deeper and shallower parts of the pool, providing evidence that there are different subsite microclimates, which may impact the populations and the isotopic composition of gastropod shells. We measured gastropod population diversity amongst nearly 12,000 shells sampled at Horseshoe springs, finding low population diversity (Shannon’s Diversity Index of 0.432), although the populations of shallow and deep snails are slightly different. The dominant snail at HRS is the Pyrgulopsis which is imperiled, and we also note that we did not find living snails here. We evaluated the bulk shell variation of stable carbonate isotopes (δ13C, and δ18O) across sites and genera. We show that there were no significant subsite-level differences in gastropod δ13C compositions, suggesting that water depth and productivity were not impacting the isotopic signal. We found subsite- and genera-specific differences in snail δ18O compositions, which we interpret to be more dependent on the geography and microclimate of where the snail lived rather than the genera’s physiology (pulmonate versus gil-breathing). We report concentrations of alkali metals (Li, Na, K, Rb, Cs), alkali earth metals (Be, Mg, Ca, Sr, Ba), and metals and metalloids (Al, Sc, Mn, Fe, Cu, Ni, Zn, As) at spring site waters and in bulk shells as potential baseline data for interpreting future or past environmental changes as recorded in shell material. We found trace element concentration and certain elemental ratio differences between genera at the same site (particularly of note were Li, Zn, Mn and Al) that will be important to constrain if these shells are to be applied as a paleoenvironmental proxy and are sometimes attributed to land use change.

Neighbourhood species richness and drought-tolerance traits modulate tree growth and δ13 C responses to drought.

Mixed-species forests are promoted as a forest management strategy for climate change adaptation, but whether they are more resistant to drought than monospecific forests remains contested. In particular, the trait-based mechanisms driving the role of tree diversity under drought remain elusive. Using tree cores from a large-scale biodiversity experiment, we investigated tree growth and physiological stress responses (i.e. increase in wood carbon isotopic ratio; δ13 C) to changes in climate-induced water availability (wet to dry years) along gradients in neighbourhood tree species richness and drought-tolerance traits. We hypothesized that neighbourhood species richness increases growth and decreases δ13 C and that these relationships are modulated by the abiotic (i.e. climatic conditions) and the biotic context. We characterised the biotic context using drought-tolerance traits of focal trees and their neighbours. These traits are related to cavitation resistance versus resource acquisition and stomatal control. Tree growth increased with neighbourhood species richness. However, we did not observe a universal relief of water stress in species-rich neighbourhoods. The effects of neighbourhood species richness and climate on growth and δ13 C were modulated by the traits of focal trees and the traits of their neighbours. At either end of each drought-tolerance gradient, species responded in opposing directions during dry and wet years. We show that species' drought-tolerance traits can explain the strength and nature of biodiversity-ecosystem functioning relationships in experimental tree communities experiencing drought. Mixing tree species can increase growth but may not universally relieve drought stress.

A framework for assessing the impacts of land-use/cover change and climate change on wheat productivity under 1.5 and 2.0 °C warming at watershed scale.

Irrigation is used extensively to enhance grain production and ensure food security. Many studies have used crop models and global climate models to study the variation of irrigated crop yield in the context of climate change. But most considered the influence of direct climate change but neglected the influence of irrigation water availability, which is affected by land-use/cover change (LUCC) and indirect climate change, on irrigated crop yield. This study therefore developed a framework including Patch-generating Land Use Simulation model, Soil and Water Assessment Tool, Agricultural Production Systems sImulator Model, and global climate models for exploring the impacts of LUCC, direct climate change, and indirect climate change on wheat yield in a typical watershed. Both LUCC and climate change caused increased runoff from October to May, and thus increased the irrigation water availability, by 51.6 and 30.7 mm per growing season under 1.5 and 2.0 °C warming, respectively. The combined influence of LUCC, direct, and indirect climate change increased wheat yield by about 18.5% and 15.5% in the context of 1.5 and 2.0 °C warming, respectively. The relative contribution of LUCC, indirect climate change and direct climate change to yield was 4.7%, 41.2%, and 54.1% under 1.5 °C warming, and 13.1%, 28.7%, and 58.2% under 2.0 °C warming, respectively. We suggest that changes in irrigation water availability should be considered from a watershed perspective when simulating the influence of climate change on crop yield, especially regional crop production estimation. © 2023 Society of Chemical Industry.