Variable Precipitation Regimes Research Articles

Seed source environment predicts response to water availability in Plantago patagonica

The intensity, duration, and severity of drought increasing across the American Southwest. Plant restoration efforts are often thwarted by drought‐induced effects (i.e. drought‐induced mortality or failure to reproduce). Careful selection of plant materials to match future environmental conditions could improve restoration success under climate change. Here, we focus on Plantago patagonica, a priority arid land restoration species in the southwestern US. Using experimental drought in a greenhouse and supplemental watering in a common garden experiment, we quantified how the seed‐collection site environment influenced plant growth, performance, phenotypic plasticity, and evidence of local adaptation in 12 populations of P. patagonica. In the greenhouse, we found plants from hotter and drier environments had higher root:shoot ratios, while those from more variable precipitation regimes had greater total biomass in response to drought. Populations sourced from warmer environments exhibited sevenfold greater plasticity in root:shoot ratio compared to those from cooler environments, and there was strong evidence for local adaptation in phenology, as populations sourced from geographic locations nearer the common garden exhibited five times more flowering individuals than those sourced furthest from that garden. In the common garden, we found that plants sourced from wetter locations and those with more consistent precipitation regimes had lower mortality and higher specific leaf area, a proxy for growth, under unwatered ambient conditions. These results suggest plant performance of P. patagonica under reduced water availability is strongly shaped by the seed‐collection site environment and may be a useful tool for improving restoration outcomes in a changing world.

The Severity of the 2014–2015 Snow Drought in the Oregon Cascades in a Multicentury Context

AbstractThe western United States (US) is a hotspot for snow drought. The Oregon Cascade Range is highly sensitive to warming and as a result has experienced the largest mountain snowpack losses in the western US since the mid‐20th century, including a record‐breaking snow drought in 2014–2015 that culminated in a state of emergency. While Oregon Cascade snowpacks serve as the state's primary water supply, short instrumental records limit water managers' ability to fully constrain long‐term natural snowpack variability prior to the influence of ongoing and projected anthropogenic climate change. Here, we use annually‐resolved tree‐ring records to develop the first multi‐century reconstruction of Oregon Cascade April 1st Snow Water Equivalent (SWE). The model explains 58% of observed snowpack variability and extends back to 1688 AD, nearly quintupling the length of the existing snowpack record. Our reconstruction suggests that only one other multiyear event in the last three centuries was as severe as the 2014–2015 snow drought. The 2015 event alone was more severe than nearly any other year in over three centuries. Extreme low‐to‐high snowpack “whiplash” transitions are a consistent feature throughout the reconstructed record. Multi‐decadal intervals of persistent below‐the‐mean peak SWE are prominent features of pre‐instrumental snowpack variability, but are generally absent from the instrumental period and likely not fully accounted for in modern water management. In the face of projected snow drought intensification and warming, our findings motivate adaptive management strategies that address declining snowpack and increasingly variable precipitation regimes.

Mitigating buffelgrass invasion through simulated targeted grazing: understanding restoration potential in a variable precipitation regime

The potential for targeted grazing for restoration through the removal of invasive species represents an effective tool for practitioners. This study examines the impact of targeted grazing across highly variable precipitation on buffelgrass, a widely introduced African grass that often escapes cultivation. We simulated targeted grazing, overgrazing, and no grazing by clipping at two intensities and not clipping in a third treatment. We did this in plots with buffelgrass invasion and documented buffelgrass size and reproduction, as well as native plant community diversity. Additionally, as a further proxy for grazing, we tracked root allocation by buffelgrass in mowed and unmowed plots for 25 months while documenting large variability in precipitation. We found that targeted grazing reduced the negative impact of buffelgrass on the native community; on the other hand, overgrazing reduced the native community diversity. Precipitation interacted with simulated grazing such that buffelgrass subjected to grazing was less tolerant to drought and future simulated herbivory after rains returned. Long‐term targeted grazing may lead to reductions in buffelgrass that allow the restoration of the native plant community, which benefits the biodiversity of flora and fauna, and supports multiple uses of rangelands.

Divergent climate impacts on C3 versus C4 grasses imply widespread 21st century shifts in grassland functional composition

AbstractAimGrasslands cover a third of Earth's landmass and provide critical ecosystem services. Anticipating how perennial C3 (cool‐season) and C4 (warm‐season) grasses respond to climate change will be key to predicting future composition and functioning of grasslands. Here, we evaluate environmental drivers of C3 and C4 perennial distributions and assess how C3 and C4 grass distributions shift in response to future climate change.LocationWestern United States.MethodsWe developed integrated species distribution models to identify climate and soil drivers of relative abundance of C3 and C4 perennial grasses. We then created projections of species abundances under future climate and evaluated when and where projected shifts in relative abundance were robust across climate models.ResultsHistorically, C3 grasses occupied areas with lower temperature and more variable precipitation regimes, while C4 grasses occupied areas of higher temperature, greater temperature variability and greater warm‐season precipitation. C4 species also occupied narrower soil texture niches. In response to future climate change, C3 grass abundance declined across 74% of areas, while C4 abundance increased across 66% of areas. C3 grasses expanded in mid‐ to higher‐latitude areas with increasing temperature and decreasing seasonality of precipitation. In contrast, C4 grasses increased in higher‐latitude regions, but declined in lower‐latitude, dryer regions. Results were surprisingly robust across climate scenarios, suggesting high confidence in the direction of these future changes.Main ConclusionsFindings imply C3 and C4 perennial grasses will have highly divergent responses to climate change that may result in grassland functional compositional changes. Increasing temperatures and precipitation variability may favour some C4 grasses, but C4 habitat expansion may be constrained by soil conditions in western USA. Results provide actionable insights for anticipating the impacts of climate change on grass‐dominated and co‐dominated ecosystems and improving large‐scale conservation and restoration efforts.

Multiple global change drivers show independent, not interactive effects: a long-term case study in tallgrass prairie.

Ecosystems are faced with an onslaught of co-occurring global change drivers. While frequently studied independently, the effects of multiple global change drivers have the potential to be additive, antagonistic, or synergistic. Global warming, for example, may intensify the effects of more variable precipitation regimes with warmer temperatures increasing evapotranspiration and thereby amplifying the effect of already dry soils. Here, we present the long-term effects (11 years) of altered precipitation patterns (increased intra-annual variability in the growing season) and warming (1°Cyear-round) on plant community composition and aboveground net primary productivity (ANPP), a key measure of ecosystem functioning in mesic tallgrass prairie. Based on past results, we expected that increased precipitation variability and warming would have additive effects on both community composition and ANPP. Increased precipitation variability altered plant community composition and increased richness, with no effect on ANPP. In contrast, warming decreased ANPP via reduction in grass stems and biomass but had no effect on the plant community. Contrary to expectations, across all measured variables, precipitation and warming treatments had no interactive effects. While treatment interactions did not occur, each treatment did individually impact a different component of the ecosystem (i.e., community vs. function). Thus, different aspects of the ecosystem may be sensitive to different global change drivers in mesic grassland ecosystems.

Local adaptation of seed and seedling traits along a natural aridity gradient may both predict and constrain adaptive responses to climate change.

Variation in seed and seedling traits underlies how plants interact with their environment during establishment, a crucial life history stage. We quantified genetic-based variation in seed and seedling traits in populations of the annual plant Plantago patagonica across a natural aridity gradient, leveraging natural intraspecific variation to predict how populations might evolve in response to increasing aridity associated with climate change in the Southwestern U.S. We quantified seed size, seed size variation, germination timing, and specific leaf area in a greenhouse common garden, and related these traits to the climates of source populations. We then conducted a terminal drought experiment to determine which traits were most predictive of survival under early-season drought. All traits showed evidence of clinal variation-seed size decreased, germination timing accelerated, and specific leaf area increased with increasing aridity. Populations with more variable historical precipitation regimes showed greater variation in seed size, suggestive of past selection shaping a diversified bet-hedging strategy mediated by seed size. Seedling height, achieved via larger seeds or earlier germination, was a significant predictor of survival under drought. We documented substantial interspecific trait variation as well as clinal variation in several important seed and seedling traits, yet these slopes were often opposite to predictions for how individual traits might confer drought tolerance. This work shows that plant populations may adapt to increasing aridity via correlated trait responses associated with alternative life history strategies, but that trade-offs might constrain adaptive responses in individual traits.

Changes of streamflow regulation in an Andean watershed with shrinking glaciers: implications for water security

ABSTRACT Glaciated Andean mountains have experienced several decades of shrinkage in their transition to non-glaciated regimes. This study analyses the period of hydrologic transition from 1956 to 2020 in a watershed of the Sierra Nevada del Cocuy (SNC), which is the most extensive remaining tropical glacier in Colombia. Using ground hydrometeorological data, remote sensing products, a metric of extreme flow regulation, and decadal flow duration curves, the study shows how the combined effect of continuous glacier shrinkage, highly variable precipitation regimes and increasing human extractions have altered the hydrological capacity of the watershed to regulate high, low, and mean flows. The alteration is noticeable since the 2000s, when communities have effectively benefited from the surplus of baseflow provided by the shrinking glacier to the limit, creating an unsustainable dependency with potential restrictions of use in the short run and major implications for water security of humans and the environment in the forthcoming decades.

Ensemble Climate and Streamflow Projections for the Assiniboine River Basin, Canada

The Assiniboine River Basin (ARB) is subject to an exceptionally variable precipitation regime of the Canadian Prairies, ranging between record droughts and unprecedented flooding in just the past decade. To assess the impact of a changing climate on hydroclimate variability in the ARB, we used the bias–corrected simulations from the Canadian Regional Climate Model (CanRCM4) to drive MESH model for two 60–year periods, a historical baseline (1951–2010) and future projection (2041–2100), under the Representative Concentration Pathway (RCP) 8.5 to simulate ARB flows at eight hydrometric stations. The precipitation is projected to increase in every season (~10–38%) except for summer (~−1–−5%). Minimum winter and maximum summer temperatures have the largest seasonal trends, increasing by 2–3 °C in the near future (2021–2050) and 5–6 °C in the far future (2051–2080). These climate changes produce higher winter river flows while peak runoff shifts by several weeks to earlier in the year. There is a shift in the magnitude and timing of extreme water levels. The ensemble of climate projections from a single model and one RCP to the variability and uncertainty in the future hydrology supports adaptation planning in the industrial sectors of Saskatchewan’s economy.

Simulating environmentally‐sensitive tree recruitment in vegetation demographic models

Vegetation demographic models (VDMs) endeavor to predict how global forests will respond to climate change. This requires simulating which trees, if any, are able to recruit under changing environmental conditions. We present a new recruitment scheme for VDMs in which functional-type-specific recruitment rates are sensitive to light, soil moisture and the productivity of reproductive trees. We evaluate the scheme by predicting tree recruitment for four tropical tree functional types under varying meteorology and canopy structure at Barro Colorado Island, Panama. We compare predictions to those of a current VDM, quantitative observations and ecological expectations. We find that the scheme improves the magnitude and rank order of recruitment rates among functional types and captures recruitment limitations in response to variable understory light, soil moisture and precipitation regimes. Our results indicate that adopting this framework will improve VDM capacity to predict functional-type-specific tree recruitment in response to climate change, thereby improving predictions of future forest distribution, composition and function.

Saving all the pieces: An inadequate conservation strategy for an endangered amphibian in an urbanizing area

Species conservation often focuses on preserving populations on remnant habitat patches, typically without evidence that this approach is sufficient for halting declines. We employed a 19-year dataset to examine the adequacy of this approach for recovering the Sonoma County distinct population segment of California tiger salamanders (SCTS; Ambystoma californiense), California, USA, which now exists almost entirely in remnant habitat patches designated as preserves across a rapidly urbanizing landscape. We estimated relative SCTS larval densities from standardized annual surveys from 2002 to 2020 across 118 vernal pools in eight preserves. We found that relative larval SCTS densities decreased by 48% over the study period, indicating that current efforts to conserve SCTS are inadequate for long-term viability. Increased densities were only observed at the single study preserve where SCTS were introduced. Temporal trends in larval density among preserves were best explained by the number of pools available to SCTS, and the ability of breeding pools to retain water throughout the larval period. Specifically, preserves with >1 breeding pool and ≥1 breeding pool that held water for at least two months following the breeding season (into late April) even in dry years had substantially lower rates of larval decline. Active conservation management of preserves, including provision of multiple breeding pools, at least some of which are resilient to variable future precipitation regimes, will be required to effectively conserve SCTS. We expect these findings to apply broadly to the conservation of many species of pool-breeding amphibians.

Interannual variation in rainfall modulates temperature sensitivity of carbon allocation and flux in a tropical montane wet forest.

Tropical forests exert a disproportionately large influence on terrestrial carbon (C) balance but projecting the effects of climate change on C cycling in tropical forests remains uncertain. Reducing this uncertainty requires improved quantification of the independent and interactive effects of variable and changing temperature and precipitation regimes on C inputs to, cycling within and loss from tropical forests. Here, we quantified aboveground litterfall and soil-surface CO2 efflux ("soil respiration"; FS ) in nine plots organized across a highly constrained 5.2°C mean annual temperature (MAT) gradient in tropical montane wet forest. We used five consecutive years of these measurements, during which annual rainfall (AR) steadily increased, in order to: (a) estimate total belowground C flux (TBCF); (b) examine how interannual variation in AR alters the apparent temperature dependency (Q10 ) of above- and belowground C fluxes; and (c) quantify stand-level C allocation responses to MAT and AR. Averaged across all years, FS , litterfall, and TBCF increased positively and linearly with MAT, which accounted for 49, 47, and 46% of flux rate variation, respectively. Rising AR lowered TBCF and FS , but increased litterfall, with patterns representing interacting responses to declining light. The Q10 of FS , litterfall, and TBCF all decreased with increasing AR, with peak sensitivity to MAT in the driest year and lowest sensitivity in the wettest. These findings support the conclusion that for this tropical montane wet forest, variations in light, water, and nutrient availability interact to strongly influence productivity (litterfall+TBCF), the sensitivity of above- and belowground C fluxes to rising MAT (Q10 of FS , litterfall, and TBCF), and C allocation patterns (TBCF:[litterfall+TBCF]).

Climate change will affect global water availability through compounding changes in seasonal precipitation and evaporation

Both seasonal and annual mean precipitation and evaporation influence patterns of water availability impacting society and ecosystems. Existing global climate studies rarely consider such patterns from non-parametric statistical standpoint. Here, we employ a non-parametric analysis framework to analyze seasonal hydroclimatic regimes by classifying global land regions into nine regimes using late 20th century precipitation means and seasonality. These regimes are used to assess implications for water availability due to concomitant changes in mean and seasonal precipitation and evaporation changes using CMIP5 model future climate projections. Out of 9 regimes, 4 show increased precipitation variation, while 5 show decreased evaporation variation coupled with increasing mean precipitation and evaporation. Increases in projected seasonal precipitation variation in already highly variable precipitation regimes gives rise to a pattern of “seasonally variable regimes becoming more variable”. Regimes with low seasonality in precipitation, instead, experience increased wet season precipitation.

Physiological acclimation of a grass species occurs during sustained but not repeated drought events

Climate change is predicted to result in more variable and extreme precipitation regimes, with potentially longer periods between precipitation events. However, the effects of multiple, sequential drought events on ecosystems and potential acclimation, particularly in grasslands, is poorly understood. In this study, we tested if two simulated drought regimes, (i) sustained drought (soil moisture content reduced from 75 to 25 % field capacity over 14 days and maintained for 29 days) and (ii) repeated drought (two cycles of a reduction to 25 % field capacity, reached after 22 days and 15 days, separated by a rewatering event to 75 % field capacity for 5 days), differentially influence fourteen key physiological responses in the model grass species (Brachypodium distachyon). In addition, we aimed to determine whether plants may acclimate differently to sustained and/or repeated drought events. B. distachyon exhibited plasticity in response to drought, exhibiting two distinct drought resistance responses to the two watering regimes. Plants exposed to sustained drought exhibited early reductions in photosynthesis, stomatal conductance and water potential (43 %, 42 % and 37 %, respectively). However, plants showed physiological acclimation and recovery in these parameters after an additional 3–21 days, but had a ∼50 % lower shoot biomass than well-watered plants. These data demonstrate a conservative, albeit plastic, response to soil water deficit. In contrast, plants exposed to repeated drought responded opportunistically whereby greater fluctuations in photosynthesis, stomatal conductance and water potential (reductions of up to 62 %, 71 % and 90 %, respectively) were closely related to drought and rewatering events. Since plants exposed to repeated drought had a greater reduction in water potential and faster reductions in relative photosynthesis in the second drought event compared to the initial drought event, this may indicate a lack of acclimation under this drought regime. Our results provide evidence for differential responses of B. distachyon to drought and rewatering events, which are dependent on the drought regime (sustained or repeated) and must be carefully considered when interpreting experimental data.

Historical Drought Affects Microbial Population Dynamics and Activity During Soil Drying and Re-Wet

A history of drought exposure promoted by variable precipitation regimes can select for drought-tolerant soil microbial taxa, but the mechanisms of survival and death of microbial populations through the selective stresses of soil drying and re-wet are not well understood. We subjected soils collected from a 15-year field drought experiment ("Altered" precipitation historywith extended dry periods,versus the "Ambient" field control) to a laboratory drying/re-wetting experiment, to learn whether selective population survival, death, or maintenance of protein synthesis potential and microbial respirationthrough variable soil water conditions was affected by field drought legacy. Microbial community composition, as measured by Illumina MiSeq sequencing of the 16S rRNA and 16S rRNA gene, shifted with laboratory drying/re-wet and field drought treatments. In Ambient soils, there was a higher proportion of reduced OTU abundance (indicative of mortality) during re-wet, whereas Altered soils had a greater proportion of stable OTU populations that did not change in abundance (indicative ofsurvival) through drying/re-wet. Altered soils alsohad a lower proportion of rRNA:rRNA genes (lower protein synthesis potential) during dry-down, a greater weighted mean rRNA operon number (potential growth rate and r-selection) which was associated with higher abundance of Firmicutes (order Bacillales), and lower average microbial respiration rates. These data demonstrate that soils with a weaker historical drought legacy exhibit a higher prevalence of microbial water-stress mortality and differential survival and death at OTU levels following short-term dryingand re-wetting, concurrent with higher carbon loss potential. This work provides novel insight into the mechanisms and consequencesof soil microbial changes resulting fromextended drought conditions.

Changes in the Atmospheric Circulation Conditions and Regional Climatic Characteristics in Two Remote Regions Since the Mid-20th Century

A meridional Northern Hemisphere (NH) circulation epoch, which began in 1957, is marked by changes in the temperature and precipitation regimes over southwest Russia and central USA depending on the occurrence of NH atmospheric circulation regimes. A classification scheme proposed in 1968, and studied later put forth 13 NH circulation types, fitting more broadly into four groups, two of which are more zonal type flows and two of which are more meridional flows. Using the results of a previous study that showed four distinct sub-periods during the 1957–2017 epoch, the temperature and precipitation regimes of both regions were studied across all seasons in order to characterize modern day climate variability and their suitability for vegetation growth. Then the Hydrologic Coefficient, which combined the temperature and precipitation variables, was briefly studied. The most optimal conditions for vegetation growth, positive temperature and precipitation anomalies, were noted during the period 1970–1980 for southwest Russia, which was dominated by an increasingly more zonal flow regime in the Belgorod region and NH in general. For the central USA, the HTC showed more ideal conditions for agriculture in recent years due to favorable precipitation occurrence. In southwest Russia, variable precipitation regimes were noted during the meridional flow periods, and with the increase in temperature (since 1998), these can adversely affect the hydrothermal characteristics of the growing season. Finally, a comparison of the 13 NH circulation types with several teleconnection indexes demonstrated the robustness of the NH flow regime classification scheme used here.

Recent hydrological variability of the Moroccan Middle Atlas Mountains inferred from microscale sedimentological and geochemical analyses of lake sediments

AbstractStudy of the hydro-sedimentary dynamics of lakes provides key information on hydrological changes. In this work, we investigate Lake Azigza in the Moroccan Middle Atlas, a region that suffers from a scarcity of observational hydrological data necessary for a coherent management of water resources. Sedimentary deposits of Lake Azigza (32°58′N, 5°26′W, 1,550 m above sea level) were dated and analyzed by combining geochemical and mineralogical measurements coupled with microfacies characterization for the last 134 yr. The detrital component derived from X-ray fluorescence elemental composition and microstructures analysis of the lake sediments provided proxies of runoff activity and lake-level changes, respectively. These proxies were calibrated with regional hydro-climatic and instrumental measurements available over the last 50 yr and used to reconstruct past hydrological changes on inter-annual to decadal time scales between 1879 and 2013. Since 1879, lake level and runoff proxies responded in phase to regional inter-annual precipitation variations. We also show that after the major lake-level drop observed in 2008, the response of the runoff proxy to variable precipitation regime is enhanced. Such an approach emphasizes the potential of these hydro-climate-sensitive sedimentary archives to assess the impact of climate change in the Mediterranean region.

A simulation of winter wheat crop responses to irrigation management using CERES-Wheat model in the North China Plain

To improve efficiency in the use of water resources in water-limited environments such as the North China Plain (NCP), where winter wheat is a major and groundwater-consuming crop, the application of water-saving irrigation strategies must be considered as a method for the sustainable development of water resources. The initial objective of this study was to evaluate and validate the ability of the CERES-Wheat model simulation to predict the winter wheat grain yield, biomass yield and water use efficiency (WUE) responses to different irrigation management methods in the NCP. The results from evaluation and validation analyses were compared to observed data from 8 field experiments, and the results indicated that the model can accurately predict these parameters. The modified CERES-Wheat model was then used to simulate the development and growth of winter wheat under different irrigation treatments ranging from rainfed to four irrigation applications (full irrigation) using historical weather data from crop seasons over 33 years (1981–2014). The data were classified into three types according to seasonal precipitation: <100 mm, 100–140 mm, and >140 mm. Our results showed that the grain and biomass yield, harvest index (HI) and WUE responses to irrigation management were influenced by precipitation among years, whereby yield increased with higher precipitation. Scenario simulation analysis also showed that two irrigation applications of 75 mm each at the jointing stage and anthesis stage (T3) resulted in the highest grain yield and WUE among the irrigation treatments. Meanwhile, productivity in this treatment remained stable through different precipitation levels among years. One irrigation at the jointing stage (T1) improved grain yield compared to the rainfed treatment and resulted in yield values near those of T3, especially when precipitation was higher. These results indicate that T3 is the most suitable irrigation strategy under variable precipitation regimes for stable yield of winter wheat with maximum water savings in the NCP. The application of one irrigation at the jointing stage may also serve as an alternative irrigation strategy for further reducing irrigation for sustainable water resources management in this area.

IKH TURGEN MOUNTAIN GLACIER CHANGE AND 3D SURFACE EXTENTS PREDICTION USING LONG TERM LANDSAT IMAGE AND CLIMATE DATA

Abstract. The glacier is most important the freshwater resources and indicator of the climate change. The researchers noted that during last decades the glacier is melting due to global warming. The study calculates a spatial distribution of protentional change of glacier coverage in the Ikh Turgen mountain of Western Mongolia, and it integrates long-term climate data and satellite datasets. Therefore, in this experiment has tried to estimation three-dimensional surface area of the glacier. For this purpose, Normalized difference snow index (NDSI) was applied to decision tree approach, using Landsat MSS, TM, ETM+ and LC8 imagery for 1975–2016, a surface and slope for digital elevation model, precipitation and air temperature historical data of meteorological station. The potential volume area significantly changed glacier cover of the Ikh Turgen Mountain, and the area affected by highly variable precipitation and air temperature regimes. Between 1972 and 2016, a potential area of glacier area has been decreased in Ikh Turgen mountain region.

Turfgrass and Climate Change

Core Ideas Climate change will affect temperature and precipitation patterns. Increasing temperatures will cause a shift in turfgrass species to more northen climates. Variation among varieties of turfgrass provide opportunity to increase climate resilience. Climate change will increase abiotic and biotic stresses on turfgrass. Climate change is occurring and is impacting biological systems through increased temperatures, more variable precipitation, and increased CO2 in the atmosphere. These effects have been documented for agricultural species, primarily grain crops, pasture and rangeland species. The extension of these relationships to turfgrass has been limited; however, these plants are an important part of our ecosystems and preservation of these plantings adds to social value and ecosystem services. Turfgrasses can be divided into cool‐season and warm‐season species and the projected changes in maximum air temperatures, along with increased root zone temperatures may promote a Northward migration of warm‐season turfgrasses. Increased spring precipitation and more variable summer precipitation coupled with more intense precipitation events are projected to occur requiring enhanced management of soil water. Turfgrass management to ensure adequate root zone soil water, and the selection of varieties or species with greater drought tolerance in the warmer regions will be necessary to preserve turfgrass plantings. Increases in CO2 benefits turfgrass growth and positively affects water use efficiency, which decreases the potential effects of a more variable precipitation regime because of impacts on soil water use. Genotypic variation in response to soil water deficits provides a foundation for screening turfgrass species to adapt to climatic stresses. Changes in temperature and precipitation variation will increase the potential for abiotic and biotic stresses on turfgrasses. Turfgrass management will require increased attention to increased abiotic and biotic stresses.

Gene expression patterns of two dominant tallgrass prairie species differ in response to warming and altered precipitation.

To better understand the mechanisms underlying plant species responses to climate change, we compared transcriptional profiles of the co-dominant C4 grasses, Andropogon gerardii Vitman and Sorghastrum nutans (L.) Nash, in response to increased temperatures and more variable precipitation regimes in a long-term field experiment in native tallgrass prairie. We used microarray probing of a closely related model species (Zea mays) to assess correlations in leaf temperature (Tleaf) and leaf water potential (LWP) and abundance changes of ~10,000 transcripts in leaf tissue collected from individuals of both species. A greater number of transcripts were found to significantly change in abundance levels with Tleaf and LWP in S. nutans than in A. gerardii. S. nutans also was more responsive to short-term drought recovery than A. gerardii. Water flow regulating transcripts associated with stress avoidance (e.g., aquaporins), as well as those involved in the prevention and repair of damage (e.g., antioxidant enzymes, HSPs), were uniquely more abundant in response to increasing Tleaf in S. nutans. The differential transcriptomic responses of the co-dominant C4 grasses suggest that these species may cope with and respond to temperature and water stress at the molecular level in distinct ways, with implications for tallgrass prairie ecosystem function.