Effects Of Extreme Drought Research Articles

Seasonal Variability and Hydrological Patterns Influence the Long-Term Trends of Nutrient Loads in the River Po

This study investigates the long-term trends (1992–2022) of nitrogen and phosphorus loadings exported by the River Po to the Adriatic Sea, to better analyse how changes in hydrology are affecting the timing and magnitude of river nutrient loads. We used 30 years of monitoring data in order to (a) identify the main temporal patterns and their interactions at a decadal, annual and seasonal scale, (b) estimate precipitation effects on load formation and evaluate whether and to which extent the hydrological regime affects nutrient export across the years and (c) analyse the nutrient export regime at a monthly scale and the main transport dynamic of N and P chemical species (hydrological vs. biogeochemical control). The long-term analysis shows a general decrease of both P and N loadings, but the trends are different between the elements and their chemical species, as well as undergoing different seasonal variations. We found a statistically significant relationships between precipitation and loads, which demonstrates that precipitation patterns drive the exported load at the intra- and interannual time scales considered in this study. Precipitation-induced load trends trigger seasonal changes in nutrient deliveries to the sea, peaking in spring and autumn. The nitrogen decrease is mainly concentrated in the summer dry period, while total phosphorus diminishes mainly in spring and autumn. This mismatch of N and P results in variable molar N:P ratios within the year. The effects of extreme drought and flood events, along with the progressive decrease in the snowmelt contribution to water fluxes, are expected to exacerbate the variability in the N and P loadings, which in turn is expected to perturbate the biodiversity, food webs and trophic state of the Northern Adriatic Sea.

Effects of extreme drought and water scarcity on consumer behaviour – The impact of water consumption awareness and Consumers’ choices

Unsustainable changes to Earth’s ecosystems and human activities are intensifying global hydrographic pressure. This study explores the connection between extreme drought, water scarcity, and consumer behaviour, investigating the potential psychological impact of these two natural hazards on individuals’ consumption behaviour. Using an integrated model grounded in the theory of interpersonal behaviour, we surveyed through an online questionnaire 244 respondents in Portugal, a region regularly affected by extreme drought. The findings reveal that affect, perceived consequences, habits, and water scarcity positively influence the intention to engage in water-saving consumption behaviour. However, this intention does not translate into actual behaviour since no positive influence is verified. In contrast, both extreme drought and water scarcity have a positive impact on behaviour, reflecting the urgency to conserve and use water efficiently. These results have theoretical and practical implications for promoting water-saving actions.

The response of photosynthetic rate of dominant species to extreme drought in Inner Mongolia grasslands

Abstract Estimating the effects of extreme drought on the photosynthetic rates (Pn) of dominant plant species is crucial for understanding the mechanisms driving the impacts of extreme drought on ecosystem functioning. Extreme drought may result from either reduced rainfall amounts or decreased rainfall frequency, and the impacts of different patterns of extreme drought may vary greatly. In addition, different grasslands likely appeared varied sensitivity to different extreme drought patterns. However, there have been no reports on the effects of different extreme drought patterns on dominant species Pn in different grassland types. Here, we conducted multi-year extreme drought simulation experiments (reducing each rainfall event by 66% during growing season, CHR vs. completely excluding rainfall during a shorter portion of growing season, INT) in two different grasslands (desert grassland vs. typical grassland) from 2014. The Pn of two dominant species in each grassland were measured in July and August 2017. Both CHR and INT significantly decreased dominant species Pn, with INT causing more negative impacts on Pn regardless of grassland types. The response ratios of Pn in desert grassland were generally higher than that of typical grassland, especially for Leymus chinensis in CHR. These results indicate that decreased rainfall frequency had a more negative effect on Pn compared to reduced rainfall amount, with grassland types changing the magnitude, but not the direction, of the effects of extreme drought patterns. These findings highlight the importance of considering extreme drought patterns and grassland types in ecosystem management in the face of future extreme droughts.

Extreme drought along the tropic of cancer (Yunnan section) and its impact on vegetation

The frequent occurrence of extreme weather events is one of the future prospects of climate change, and how ecosystems respond to extreme drought is crucial for response to climate change. Taking the extreme drought event in the Tropic of Cancer (Yunnan section) during 2009–2010 as a case study, used the standardized precipitation evapotranspiration index to analyse the impact of extreme drought on enhanced vegetation index (EVI), leaf area index (LAI) and gross primary productivity (GPP), and to analyzed the post extreme drought vegetation recovery status. The results indicate the following: (1) Due to the cumulative effects of drought and vegetation phenology, vegetation growth in the months of March to May in 2010 was more severely affected. (2) Compared to EVI and LAI, GPP is more sensitive to drought and can accurately indicate areas where drought has impacted vegetation. (3) Following an extreme drought event, 70% of the vegetation can recover within 3 months, while 2.87–6.57% of the vegetation will remain unrecovered after 6 months. (4) Cropland and grassland show the strongest response, with longer recovery times, while woodland and shrubland exhibit weaker responses and shorter recovery times. This study provides a reference for the effects of extreme drought on vegetation.

Tracking effects of extreme drought on coniferous forests from space using dynamic habitat indices

Terrestrial ecosystems such as coniferous forests in Central Europe are experiencing changes in health status following extreme droughts compounding with severe heat waves. The increasing temporal resolution and spatial coverage of earth observation data offer new opportunities to assess these dynamics. Dense time-series of optical satellite data allow for computing Dynamic Habitat Indices (DHIs), which have been predominantly used in biodiversity studies. However, DHIs cover three aspects of vegetation changes that could be affected by drought: annual productivity, minimum cover, and seasonality. Here, we evaluate the health status of coniferous forests in the federal state of Hesse in Germany over the period 2017–2020 including the severe drought year of 2018 using DHIs based on the Normalized Difference Vegetation Index (NDVI) for drought assessment. To identify the most important variables affecting coniferous forest die-off, a series of environmental variables together with the three DHIs components were used in a logistic regression (LR) model. Each DHI component changed significantly across non-damaged and damaged sites in all years (p-value 0.05). When comparing 2017 to 2019, DHI-based annual productivity decreased and seasonality increased. Most importantly, none of the DHI components had reached pre-drought conditions, which likely indicates a change in ecosystem functioning. We also identified spatially explicit areas highly affected by drought. The LR model revealed that in addition to common environmental parameters related to temperature, precipitation, and elevation, DHI components were the most important factors explaining the health status. Our analysis demonstrates the potential of DHIs to capture the effect of drought events on Central European coniferous forest ecosystems. Since the spaceborne data are available at the global level, this approach can be applied to track the dynamics of ecosystem conditions in other regions, at larger spatial scales, and for other Land Use/Land Cover types.

Methane uptake responses to extreme droughts regulated by seasonal timing and plant composition

Increasingly frequent and severe droughts are occurring in multiple seasons of a year in many dryland ecosystems, with unknown impacts on the role of drylands in cycling of methane (CH4), a potent greenhouse gas. In particular, there is limited understanding of how drought occurring at different times within the growing season regulates biological CH4 uptake, and how these responses are mediated by plant community composition. Here, we quantify how drought timing and plant community composition regulate CH4 uptake in a semiarid grassland. We employ a field experiment in which droughts were imposed in early, middle, or late growing season in three different communities (two graminoids, two shrubs and their mixture), respectively. All three droughts increased CH4 uptake, but the effect size and pathway varied with seasonal timing. Early and middle drought increased CH4 uptake through increasing both soil pomA abundance and diffusivity resulting from reduced soil water content (SWC), while late drought increased CH4 uptake only by reducing SWC. Overall, early drought had the least positive effects on CH4 uptake because it excluded the least precipitation and therefore had smaller impacts on SWC. Besides, plant composition did not affect CH4 uptake under normal environment but regulated CH4 uptake in response to droughts due to different response of plant composition to droughts. Early and middle drought had larger positive effects on CH4 uptake in shrub communities than the other two communities, consistent with larger reductions in SWC and larger increases in pomA abundance, respectively. In contrast, late drought had consistent effects on CH4 uptake across three communities. Our results suggest that the magnitude and pathways of extreme drought effects on CH4 uptake are strongly co-regulated by seasonal timing and plant composition.

DROUGHT AND HOTTER TEMPERATURE IMPACTS ON SUICIDE: EVIDENCE FROM THE MURRAY–DARLING BASIN, AUSTRALIA

The Murray–Darling Basin (MDB) is Australia’s prime agricultural region, where drought and hotter weather pose a significant threat to rural residents’ mental health – hence increasing their potential suicide risk. We investigate the impact of drought and hotter temperatures on monthly suicide within local areas in the MDB, from 2006–2016. Using Poisson fixed-effects regression modeling, we found that extreme drought and hotter temperatures were associated with increased total suicide rates. The effects of extreme drought and temperature on suicide were heterogeneous across gender and age groups, with younger men more vulnerable. Areas with higher percentages of Indigenous and farmer populations were identified as hot spots, and were vulnerable to increased temperatures and extreme drought. Green space coverage (and to some extent higher incomes) moderated the drought and suicide relationship. Providing targeted interventions in vulnerable groups and hot spot areas is warranted to reduce the suicide effect of climate change.

A novel framework for investigating the mechanisms of climate change and anthropogenic activities on the evolution of hydrological drought

Climate change and anthropogenic activity are the primary drivers of water cycle changes. Hydrological droughts are caused by a shortage of surface and/or groundwater resources caused by climate change and/or anthropogenic activity. Existing hydrological models have primarily focused on simulating natural water cycle processes, while limited research has investigated the influence of anthropogenic activities on water cycle processes. This study proposes a novel framework that integrates a distributed hydrological model and an attribution analysis method to assess the impacts of climate change and anthropogenic activities on hydrological drought The distributed dualistic water cycle model was applied to the Fuhe River Basin (FRB), and it generated a Nash–Sutcliffe efficiency coefficient > 0.85 with a relative error of <5 %. Excluding the year with extreme drought conditions, our analysis revealed that climate change negatively impacted the average drought duration (−105.5 %) and intensity (−23.6 %) because of increasing precipitation. However, anthropogenic activities continued to contribute positively to the drought, accounting for 5.5 % and 123.6 % of the average drought duration and intensity, respectively, because of increased water consumption. When accounting for extreme drought years, our results suggested that climate change has contributed negatively to the average duration of drought (−113.2 %) but positively to its intensity (7.8 %). Further, we found that anthropogenic activities contributed positively to both the average drought duration and intensity (13.2 % and 92.2 %, respectively). While climate change can potentially mitigate hydrological drought in the FRB by boosting precipitation levels, its overall effect may exacerbate drought through the amplification of extreme climate events resulting from global climate change. Therefore, greater attention should be paid to the effects of extreme drought.

Management can mitigate drought legacy effects on the growth of a moisture-sensitive conifer tree species

Understanding the impact of management upon post-drought tree growth recovery and drought legacy effects is among the fundamental challenges hindering the improvement of forest conservation strategies in the face of increasingly frequent, longer, and intensified extreme droughts under ongoing climate change. Yet surprisingly little is known to date about how management practices can influence drought legacy effects; and previous studies of management impacts on forest resilience to drought have reached inconsistent and contentious conclusions. This study sought to tackle these pressing questions and gain insight by analyzing tree-ring datasets from non-managed and managed Qinghai spruce forests in northwestern China. The results show improved growth resilience to drought of those trees under management practices. Moreover, Qinghai spruce radial growth in non-managed forest exhibited significant legacy effects of extreme drought, whereas such legacy effects were mitigated in managed forest. Nevertheless, both the resilience augmentation and the mitigation of drought legacy effects by management were much weaker in the face of a three-year persistent drought than a single-year event. Hence, we may conclude that current management practices are advantageous and necessary for forest conservation under exacerbated drought conditions, for which strategies and measures should be better thought out and tailored to specific situations, rather than being “one-size-fits-all”, to better serve the goals of forest managers and conservationists.

Effects of extreme drought on soil microbial functional genes involved in carbon and nitrogen cycling in alpine peatland

Diverse microorganisms drive biogeochemical cycles and consequently influence ecosystem-level processes in alpine peatlands, which are vulnerable to extreme drought induced by climate change. However, there are few reports about the effects of extreme drought on microbial function. Here we identify microbial functional genes associated with carbon and nitrogen metabolisms of extreme drought experiments that occurred at different periods of plant growth, the results show that early extreme drought reduces the abundance of functional genes involved in the decomposition of starch and cellulose; midterm extreme drought increases the abundance of lignin decomposition functional genes; late extreme drought reduces the hemicellulose but increases cellulose decomposition functional genes. In the carbon fixation pathway, extreme drought mainly changes the abundance of functional genes involved in the reductive citrate cycle process, the 3-hydroxy propionate bi-cycle, the dicarboxylate-hydroxybutyrate cycle and the incomplete reductive citrate cycle. Among the nitrogen cycling functional genes, amoA involved in oxidizing ammonia to hydroxylamine significantly increases under early extreme drought; midterm extreme drought reduces nrtC and nifD genes, which participate in nitrate assimilation and nitrogen fixation, respectively; late extreme drought significantly increases hcp genes involved in ammonification. pH and TN had the largest effects on the carbon degradation, fixation and nitrogen cycling functional genes. The composition of microbial community structures involved in carbon fixation differed between treatments in early extreme drought. There is a good linear fit between the diversity of gene abundance and corresponding microbial communities in the reductive citrate cycle, hydroxy propionate-hydroxybutyrate cycle, dicarboxylate-hydroxybutyrate cycle and nitrogen cycling, which suggests that the functional genes and community composition of microorganisms involved in these processes are consistent in response to extreme drought. This study provides new insights into the adaptability and response characteristics of microbial communities and functional genes in plateau peatland ecosystems to extreme drought events.

Effects of Extreme Drought and Water Scarcity on Consumer Behaviour – The Impact of Water Consumption Awareness and Consumers' Choices

Effects of Extreme Drought and Water Scarcity on Consumer Behaviour – The Impact of Water Consumption Awareness and Consumers' Choices

Extreme drought alters plant community structure by changing dominant species growth in desert grassland

AbstractQuestionsInterannual precipitation changes, both in amount and frequency, are expected to increase due to climate change, and these changes could dramatically affect the structure and function of ecosystems. However, how plant life‐forms and dominant species regulate the plant community structure after precipitation changes remains unclear.LocationGaolan Experiment Station for Ecology and Agriculture Research of the Northwest Eco‐Environment and Resources Research Institute of the Chinese Academy of Sciences, located in the desert grassland of the western Loess Plateau, China.MethodsTo investigate the effect of precipitation changes on the growth of communities, life‐forms, and species, we used rain shelters and irrigation to create a variety of precipitation gradients (i.e., −40%, −20%, 0% [= CK, i.e., control treatment], +20%, +40% of ambient precipitation) in desert grasslands from 2014 to 2015.ResultsThe plant community density, coverage, and height were significantly decreased in the −40% treatment compared to CK. In contrast, species richness, Shannon–Wiener index, and Pielous' evenness did not respond significantly to the precipitation treatment. In addition, at the level of life‐forms, the density of perennial herbaceous plants was significantly increased by the +40% treatment in 2015, while the richness and density of annual herb were significantly inhibited by extreme drought. The effect on the shrub growth index of increasing and decreasing precipitation compared to the CK was insignificant. Furthermore, at the level of species, the growth of dominant species was obviously suppressed by the −40% and +40% treatment in 2015. However, the positive effect of the +40% treatment on the growth of rare species reached significant levels in 2015. Also, the change in precipitation did not have a significant effect on the growth of companion species. Dominant species primarily drove the response of community‐level plant growth to precipitation changes over the three‐year study period.ConclusionThe response of plant community composition to changes in precipitation in desert grassland is largely regulated by changes in the composition of the dominant species. This finding could also provide a better prediction of the effects of extreme drought on desert grassland plant communities in the scenarios of future global climate change.

Post-drought moisture condition determines tree growth recovery after extreme drought events in the Tianshan Mountains, northwestern China

Recently, forests in the Tianshan Mountains have shown a marked decline in growth and an increased mortality rate because of the more frequent and severe effects of extreme drought, which threatens the ecosystem services they provide. To achieve forest conservation and sustainable development benefits, it is crucial to understand the post-drought recovery trajectory of tree growth and its driving factors. In this study, we quantified the growth recovery performance of dominant tree species in the Tianshan Mountains after extreme drought events and determined the influences of climate factors on forest growth resilience using tree-ring proxy data. The results showed that post-drought moisture conditions may determine the post-drought growth recovery of trees. The post-drought growth for 1997 was higher than that for 1974, which may be attributed to the subsequent period of 1997 experiencing very high precipitation, whereas the year following the 1974 drought was dry (Standardized Precipitation Evapotranspiration Index < 0). Because of the more favorable climate conditions in the post-drought period, the observed relationship between resistance and recovery in 1997 showed a closer fit to the hypothetical “line of full resilience” which sets resilience to a constant value of 1, allowing trees to recover fully at any given value of resistance. Trees showed lower mean values of the tree growth recovery index (RC) and average recovery rate (ARR) and higher mean values of total growth reduction (TGR) and recovery period (RE) for the drought event in 1974 than that in 1997. We distinguished the relative influence of temperature and precipitation on different drought phases using Boosted Regression Tree (BRT) model. The results showed that the climate conditions during the drought year and subsequent precipitation variation were most influential variables for tree growth recovery. Specifically, post-drought precipitation explained up to 20 % of the variance in RC, TGR, RE, and ARR. These findings deepen our understanding of the impacts of prolonged drought on tree growth, which could aid in developing forest management and conservation strategies to respond to extreme drought.

Effects of Extreme Drought and Heat Events on Leaf Metabolome of Black Alder (Alnus glutinosa L.) Growing at Neighboring Sites with Different Water Availability

Riparian tree species are thought to be sensitive to the more frequent and intensive drought and heat events that are projected to occur in the future. However, compared to waterlogging, information about the responses of these tree species to water limitation and heat is still scare. Black alder (Alnus glutinosa L.) is a riparian tree species with significant ecological and economic importance in Europe. In the present study, we investigated the physiological responses of black alder (Alnus glutinosa L.) to different water availabilities growing at neighboring sites. Compared to trees with unlimited water source, trees with a limited water source had 20% lower leaf hydration, 39% less H2O2 contents, and 34% lower dehydroascorbate reductase activities. Concurrent with dramatically accumulated glutathione and phenolic compounds, leaf glutathione contents were two times higher in trees with limited water than in trees with sufficient water. Limited water availability also resulted in increased abundances of sugars, sugar acids, and polyols. Serine, alanine, as well as soluble protein related to nitrogen metabolism were also accumulated under limited water conditions. In contrast to sulfate, leaf phosphate contents were significantly increased under limited water. No significant effects of water conditions on malondialdehyde and ascorbate contents and fatty acid abundances were observed. The present study improves our understanding of the physiological responses of black alder to different water conditions. Our findings highlight this riparian species is at least to some extent resistant to future drought with a well-regulated system including antioxidative and metabolic processes and its potential as an admixture candidate for afforestation in either water-logged or dry areas, particularly in nitrogen limited habitats.

The effects of previous summer drought and fertilization on winter non-structural carbon reserves and spring leaf development of downy oak saplings.

It is still unknown whether the previous summer season drought and fertilization will affect the winter non-structural carbohydrate (NSC) reserves, spring leaf development, and mortality of trees in the next year. We, therefore, conducted an experiment with Quercus pubescens (downy oaks) saplings grown under four drought levels from field capacity (well-watered; ~25% volumetric water content) to wilting point (extreme drought; ~6%), in combination with two fertilizer treatments (0 vs. 50kg/ha/year blended) for one growing season to answer this question. We measured the pre- and post-winter NSC, and calculated the over-winter NSC consumption in storage tissues (i.e. shoots and roots) following drought and fertilization treatment, and recorded the spring leaf phenology, leaf biomass, and mortality next year. The results showed that, irrespective of drought intensity, carbon reserves were abundant in storage tissues, especially in roots. Extreme drought did not significantly alter NSC levels in tissues, but delayed the spring leaf expansion and reduced the leaf biomass. Previous season fertilization promoted shoot NSC use in extreme drought-stressed saplings over winter (showing reduced carbon reserves in shoots after winter), but it also showed positive effects on survival next year. We conclude that: (1) drought-stressed downy oak saplings seem to be able to maintain sufficient mobile carbohydrates for survival, (2) fertilization can alleviate the negative effects of extreme drought on survival and recovery growth of tree saplings.

Compound hydroclimatic extremes in a semi-arid grassland: Drought, deluge, and the carbon cycle.

Climate change is predicted to increase the frequency and intensity of extreme events including droughts and large precipitation events or "deluges." While many studies have focused on the ecological impacts of individual events (e.g., a heat wave), there is growing recognition that when extreme events co-occur as compound extremes, (e.g., a heatwave during a drought), the additive effects on ecosystems are often greater than either extreme alone. In this study, we assessed a unique type of extreme-a contrasting compound extreme-where the extremes may have offsetting, rather than additive ecological effects, by examining how a deluge during a drought impacts productivity and carbon cycling in a semi-arid grassland. The experiment consisted of four treatments: a control (average precipitation), an extreme drought (<5th percentile), an extreme drought interrupted by a single deluge (>95th percentile), or an extreme drought interrupted by the equivalent amount of precipitation added in several smaller events. We highlight three key results. First, extreme drought resulted in early senescence, reduced carbon uptake, and a decline in net primary productivity relative to the control treatment. Second, the deluge imposed during extreme drought stimulated carbon fluxes and plant growth well above the levels of both the control and the drought treatment with several additional smaller rainfall events, emphasizing the importance of precipitation amount, event size, and timing. Third, while the deluge's positive effects on carbon fluxes and plant growth persisted for 1month, the deluge did not completely offset the negative effects of extreme drought on end-of-season productivity. Thus, in the case of these contrasting hydroclimatic extremes, a deluge during a drought can stimulate temporally dynamic ecosystem processes (e.g., net ecosystem exchange) while only partially compensating for reductions in ecosystem functions over longer time scales (e.g., aboveground net primary productivity).

Extreme drought decreases soil heterotrophic respiration but not methane flux by modifying the abundance of soil microbial functional groups in alpine peatland

Extreme drought can have a substantial effect on the soil water content, soil microbial community structure and function, soil heterotrophic respiration (Rh), and soil methane (CH4) flux. However, the effects of extreme drought on Rh and CH4 flux at different plant growth stages (rapid growth, full bloom, and decline stages) and the main factors driving changes in Rh and CH4 flux remain unclear. We conducted an experiment to reveal the responses of Rh, CH4 flux, and the microbial community to extreme drought and the main factors affecting Rh and CH4 flux. Extreme drought significantly decreased Rh (from 69.41 to 31.37 mg m−2h−1) at the decline stage but had no significant effect on CH4 flux. Extreme drought significantly decreased bacterial α-diversity, markedly decreased the relative abundance of Rokubacteria and Chloroflexi at the rapid growth stage and decline stage, and significantly increased the relative abundance of Actinobacteria at the full bloom stage. At the rapid growth and full bloom stages, extreme drought significantly decreased the relative abundance of aromatic hydrocarbon degraders by 50.26% and 64.37%, respectively. At the decline stage, extreme drought significantly decreased the relative abundance of methanol oxidizers and lignin degraders by 81.63% and 82.08%, respectively. A random forest model analysis revealed the most important role of bacterial functional groups in determing Rh and CH4 flux. The aromatic compound degraders and aromatic hydrocarbon degraders amounted to 11.89 % of contribution to Rh, and aromatic compound degraders, aromatic hydrocarbon degraders, aliphatic non-methane hydrocarbon degraders, and methylotrophs amounted to 13.29 % of contribution to CH4 flux. Our findings indicate that microbial functional groups involved in carbon cycles are important factors explaining variation in Rh and CH4 flux and are critical for exploring the possible microbial response mechanism of soil carbon cycling under future scenarios of extreme drought.

Effects of extreme drought and extreme precipitation on aboveground productivity of ephemeral plants across different slope positions along sand dunes

Effects of extreme drought and extreme precipitation on aboveground productivity of ephemeral plants across different slope positions along sand dunes

Effects of extreme drought on community and ecological network of soil fungi in a temperate desert

Effects of extreme drought on community and ecological network of soil fungi in a temperate desert

Responses of soil extracellular enzyme activities and bacterial community composition to seasonal stages of drought in a semiarid grassland

Extreme drought can strongly impact belowground communities and biogeochemical processes, including soil microbial community composition and extracellular enzyme activities (EEAs), which are considered key agents in ecosystem carbon (C) and nutrient cycling. However, our understanding of how seasonal timing of drought during the growing season affects soil microbial communities and their activity remains notably poor. In this study, we investigated the responses of soil physicochemical properties, EEAs, and bacterial community composition to extreme-duration drought imposed in the early-, mid-, or late-stages of the growing season in a semiarid grassland ecosystem in Inner Mongolia, China. Compared with the ambient control, the activities of C-, nitrogen (N)-, and phosphorus (P)-acquisition enzymes were significantly decreased in the mid- and/or late-stages of drought. Bacterial community diversity also significantly decreased in the mid- and late-stage drought treatments. Soil water content was the most important factor explaining changes in soil EEAs and bacterial community composition. At the end of the growing season, the activities of C-, N-, and P-acquisition enzymes had mostly recovered, while the bacterial community diversity in the mid- and late-stage drought treatments was still lower than the ambient control. Overall, our study demonstrates that the effects of extreme drought on soil EEAs and bacterial community composition depend on the timing of drought. Our results highlight that understanding the effects of extreme-duration drought at different stages of the growing season may play a vital role in predicting the responses of belowground function to global changes in grassland ecosystems.