Dryland Wetland Research Articles

Predicting trajectories of dryland wetland vegetation transformation under climate change: a case study of the northern Murray–Darling Basin, Australia

Dryland wetland vegetation is, paradoxically, both highly sensitive and extremely resilient to environmental change. In the short-term, rapid responses of wetland biota and ecological processes to wetting and drying, which influence ecosystem structure and function, enable rapid reproduction which enhances long-term resilience. However, over longer periods, mechanisms such as seed dormancy and persistent seed and egg banks enable dryland wetland ecosystems to recover after major environmental perturbations such as mega-droughts or wildfire. Climate change is likely to have a significant effect on key drivers of ecological response in dryland wetlands, including hydrology and its interface with other climatic stimuli, e.g. temperature, as well as the frequency and intensity of extreme events. Like species, wetland ecosystems may respond to climate change in three main ways, namely, disappear, persist without significant adjustment, or transform. Here, we consider the conditions under which each of these responses may eventuate for dryland wetlands, by using wetland vegetation of the northern Murray–Darling Basin Australia, as a case study. We also explore what wetland transformation might entail in this region in terms of wetland ecological character and the key values this supports. Finally, we consider the implications for wetland policy and management at present and as trajectories of wetland change unfold.

Landscape-wide pulse events predict trait-based responses among wetland birds in perennial channels of a dryland wetland.

Wetlands in arid or semiarid zones are vital for maintaining biodiversity but face growing threats. Flooding regime variability is a key driver of ecological dynamism in these systems, dictating primary productivity on a large spatial scale. The functional composition or diversity of wetland-dependent bird species has been found to be sensitive to fluctuations in hydrological regimes and can thus be indicative of cascading ecosystem responses associated with climate change. In this paper, we investigate whether large-scale changes in inundation and fire-a significant additional biodiversity determinant in (semi-)arid landscapes-are reliable predictors of functional group responses of wetland-dependent birds along a perennial channel of the Okavango Delta, Botswana. We fit generalized additive models (GAMs) to 6 years of bird survey data collected along ~190-km-long annual transects and use remotely sensed landscape-level inundation estimates, as well as spatiotemporal distance to fire, to predict the responsiveness of seven trait-based functional group abundances. During the surveys, a total of 89 different wetland-dependent bird species were recorded, including 76 residents, across all years, with below-surface feeding waders consistently the most abundant functional group. Including estimated spatiotemporal variability in flooding and fire, as well as their interactions, improved model fit for all seven functional groups, explaining between 46.8% and 68.3% of variability in functional group abundances. Covariates representing longer-term variability in inundation generally performed better than shorter-term ones. For example, variability in inundation over the 5 months preceding a survey best predicted the responses of all functional groups, which also all exhibited responsiveness to the interaction between flooding and fire. We were able to interpret the responses of individual functional groups, based on the resource exploitation assumption. Overall, our results suggest that perennial waters in dryland wetlands offer functional refugia to wetland-dependent birds and highlight the indicative power of large-scale trait-based bird monitoring. Our findings demonstrate the potential utility of such a monitoring regime for dryland wetland ecosystems vulnerable to industrial-scale anthropogenic pressure and associated climate change.

Impacts of climate change on the wetlands in the arid region of Northwestern China over the past 2 decades

Climate change has caused inland wetlands shrinkage and exacerbated problems, such as sustainable development and ecological security, for years. These issues are mainly pronounced in the inland arid area. The ecological environment’s deterioration is especially severe in the drylands of the interior. However, dryland wetland changes and their response to climate are poorly understood. This study uses the K-means algorithm in Google Earth Engine (GEE) to classify two typical dryland wetlands (Ebinur and Bosten Lakes) for rapidly and accurately detecting dryland wetland changes. Moreover, it explores the long-term spatial–temporal variation in wetland distribution. In addition, it investigates the response of various lakes to climate change in northern and southern Xinjiang using wavelet analysis. The study’s results showed that K-means clustering in the GEE platform has a high classification accuracy (Kappa > 0.8) in wetland classification, making it a feasible approach. The terminal lake wetland types, represented by the Ebinur Lake, changed significantly between 2001 and 2021. In contrast, the inflow-outflow lake wetland types, represented by the Bosten Lake, perform more consistently. Significant spatial–temporal variation is observed at Ebinur Lake, with the lake gradually shrinking and transforming into a marsh, where the largest marsh proportion degrades into non-wetland during the year. Bosten Lake experienced frequent conversions between marsh and non-wetland throughout the year. Furthermore, the responses of various dryland lakes to climate change are consistent, and a low precedes precipitation and follows evapotranspiration. However, their sensitivity to climate response varies, with the terminal lake being most affected by climate change. Mastering the dynamic changes and climate response of dryland wetlands achieves the sustainable development goals of drylands, including carbon neutrality and peak carbon dioxide emissions.

A Random Forest-Based Multi-Index Classification (RaFMIC) Approach to Mapping Three-Decadal Inundation Dynamics in Dryland Wetlands Using Google Earth Engine

Australian inland riparian wetlands located east of the Great Dividing Range exhibit unique, hydroecological characteristics. These flood-dependent aquatic systems located in water-limited regions are declining rapidly due to the competitive demand for water for human activities, as well as climate change and variability. However, there exist very few reliable data to characterize inundation change conditions and quantify the impacts of the loss and deterioration of wetlands. A long-term time record of wetland inundation maps can provide a crucial baseline to monitor, assess, and assist the management and conservation of wetland ecosystems. This study presents a random forest-based multi-index classification algorithm (RaFMIC) on the Google Earth Engine (GEE) platform to efficiently construct a temporally dense, three-decadal time record of inundation maps of the southeast Australian riparian inland wetlands. The method was tested over the Macquarie Marshes located in the semiarid region of NSW, Australia. The results showed a good accuracy when compared against high-spatial resolution imagery. The total inundated area was consistent with precipitation and streamflow patterns, and the temporal dynamics of vegetation showed good agreement with the inundation maps. The inundation time record was analysed to generate inundation probability maps, which were in a good agreement with frequently flooded areas simulated by a hydrodynamic model and the distribution of flood-dependent vegetation species. The long-term, time-dense inundation maps derived from the RaFMIC method can provide key information to assess the condition and health of wetland ecosystems and have the potential to improve wetland inventory with spatially explicit water regime information. RaFMIC can be adapted over other dryland wetlands, as an effective semiautomated method of mapping long-term inundation dynamics.

Contemporary channel adjustment and geomorphic sensitivity of the lower Mara River and its floodplain wetlands, Tanzania

An understanding of river adjustment processes, previous landform changes, and sensitivity to flow regimes are prerequisites for predicting how rivers may respond to future climate change and anthropogenic disturbance. Geomorphic river sensitivity is an important concept that can be used to assess the capacity of adjustment for a river type and forecast river responses to hydroclimatic change over time. In this study, we use satellite imagery to characterise and quantify recent geomorphic river adjustment in a dryland river in East Africa, over the past 32 years (1988–2020). The natural or expected river behaviour (i.e., behavioural regime) and capacity for adjustment (i.e., valley confinement) are quantified to provide a measure of the reach-scale geomorphic sensitivity of the lower Mara River, Tanzania. Two behavioural river sensitivity classes are identified. The upper reach is classified as Passive sensitive, exhibiting a limited range of bend adjustments and low migration rates (0.89 m a−1) owing to valley confinement and capacity to recover from disturbance events. The middle reach is classified as Fragile and shows the greatest capacity to adjust in response to intrinsic fluxes. This reach is characterised by numerous lateral migration features and cut-offs (0.2/km) on the floodplain and exhibits the highest migration rates (1.39 m a−1). The lower reach is also categorised as Passive sensitive and undergoes bend and boundary adjustments within its behavioural regime and exhibits the lowest migration rates (0.63 m a−1). However, this reach appears to be operating close to a threshold state and if subjected to a threshold-breaching disturbance event it may ‘switch’ to a Fragile system where avulsions are dominant. The Mara River shows that geomorphic sensitivity is an important consideration in assessing system response to short-term variability and forecasting future river behaviour and will be key in guiding the management and rehabilitation efforts of other dryland wetlands under different land use and climate change scenarios.

Surface water and aerosol spatiotemporal dynamics and influence mechanisms over drylands

Under the background of global warming and excessive human activities, much surface water in drylands is experiencing rapid degradation or shrinkage in recent years. The shrinkage of surface water, especially the degradation of lakes and their adjacent wetlands in drylands, may lead to the emergence of new salt dust storm hotspots, which causes greater danger. In this paper, based on high spatial resolution global surface water (GSW) and multiangle implementation of atmospheric correction (MAIAC) AOD data, we systematically analyze the dynamic characteristics of surface water and aerosols in typical drylands (Central Asia, CA) between 2000 and 2018. Simultaneously, combined with auxiliary environment variables, we explore the driving mechanisms of surface water on the regional salt/sand aerosols on different spatial scales. The results show that the seasonal surface water features an increasing trend, especially a more dramatic increase after 2015, and the permanent surface water indicates an overall decrease, with nearly 54.367 % at risk of receding and drying up. In typical lakes (Aral Sea and Ebinur Lake), the interannual change feature of the surface water area (WA) is that a continuous decrease during the study period occurs in Aral Sea area, yet a significant improvement has occurred in Ebinur Lake after 2015, and the degradation of Ebinur Lake takes place later and its recovery earlier than Aral Sea. The aerosol optical depth (AOD) in CA shows obvious seasonal variation, with the largest in spring (0.192 ± 0173), next in summer (0.169 ± 0.106), and the smallest in autumn (0.123 ± 0.065). The interannual variation of AOD exhibits an increase from 2000 to 2018 in CA, with high AOD areas mainly concentrated in the Taklamakan Desert and some lake beds resulting from lake degradation, including Aral Sea and Ebinur Lake. The AOD holds a similar trend between Aral Sea and Ebinur Lake on an interannual scale. And the AOD over Ebinur Lake is lower than that over Aral Sea in magnitude and lags behind in reaching the peak compared with Aral Sea. The WA change can significantly affect aerosol variation directly or indirectly on the aerosol load or mode size, but there are obvious differences in the driving mechanisms, acting paths, and influence magnitude of WA on aerosols on different spatial scales. In addition, the increase of WA can significantly directly suppress the increase of Ångström exponent (AE), and the effects of WA on AOD are realized majorly by an indirect approach. From the typical lake perspective, the effects of WA on aerosol in Aral Sea are achieved via an indirect path; and the decrease of WA can indirectly promote the AOD rise, and directly stimulate the AE growth in Ebinur Lake.

Characterizing ecosystem change in wetlands using dense earth observation time series

Wetlands in drylands are vulnerable to degradation and disappearance due to the combined effects of increasing anthropogenic disturbances and climatic extremes. Such influences may drive non-linear shifts in surface responses that require long-term monitoring approaches for their study. Here, we used a piece-wise regression model to characterize long-term Ecosystem Change Types (ECT) in the surface water and vegetation dynamics of the Inner Niger Delta wetlands in Mali between 2000 and 2019. We also examined the added benefits of using a dense Landsat time series for such segmented trend analysis in comparison with MODIS products that are regularly used for ecosystem trends assessment. Our approach has found statistically significant (p < 0.05) long-term changes in wetland ecosystems, as calculated from Modified Normalized Difference Water Index (MNDWI) and Normalized Difference Vegetation Index (NDVI) image series on both the MODIS and the Landsat scales. The class-specific accuracies of the detected ECTs were evaluated through the validation of temporal trajectories based on the TimeSync logic at selected probability sample locations. Results showed higher user's, producer's, and overall accuracies (OA) when using a dense Landsat time series (OA = 0.89 ± 0.01), outperforming the MOD09A1 time series (OA = 0.37 ± 0.03). Our study provides a robust framework for long-term wetland monitoring that demonstrates the benefits of applying dense Landsat time-series imagery for accurate quantifications of linear and non-linear ecosystem responses in vast highly dynamic floodplain systems. Delivering such an improved assessment, in a spatial resolution that better resolves the characteristics of wetlands ecosystems, has the potential to support the information needs of global conservation and restoration efforts.

Using cloud computing techniques to monitor long-term variations in ecohydrological dynamics of small seasonally-flooded wetlands in semi-arid South Africa

• Semi-arid Southern African wetlands are lost due to unsustainable use and poor management. • Ramsar Convention on wetlands encourages development of frameworks for wetlands conservation. • The implementation of these frameworks is hindered by a dearth of high-resolution data. • Google Earth Engine (GEE) offers opportunities to address data challenges. • Findings underscores the relevance of GEE in evaluating wetland ecohydrological dynamics. Wetlands in drylands have high inter- and intra-annual ecohydrological variations that are driven to a great extent by climate variability and anthropogenic influences. The Ramsar Convention on Wetlands encourages the development of frameworks for national action and international cooperation for ensuring conservation and wise use of wetlands and their resources at local, national and regional scales. However, the implementation of these frameworks remains a challenge. This is mainly due to limited availability of high-resolution data and suitable big data processing techniques for assessing and monitoring wetland ecohydrological dynamics at large spatial scales, particularly in the sub-Saharan African region. The availability of cloud computing platforms such as Google Earth Engine (GEE) offers unique big data handling and processing opportunities to address some of these challenges. In this study, we applied the GEE cloud computing platform to monitor the long-term ecohydrological dynamics of a seasonally flooded part of the Nylsvley floodplain wetland complex in north-eastern South Africa over a 20-year period (2000–2020). The specific objectives of the study were 1) to evaluate wetland ecohydrological dynamics using the 20-year multi-date Landsat composite data coupled with the Random Forest machine learning algorithm, and 2) to establish the major drivers of wetland ecohydrological changes, using selected spectral indices (i.e. Normalised Difference Vegetation Index (NDVI), Normalised Difference Water Index (NDWI) and Normalised Difference Phenology Index (NDPI)) coupled with climate data. The ecohydrology of the wetland changed over time, with some classes increasing twice when compared to the previous measurement, while others decreasing significantly during the study period. Notably, the bare surface class increased at rates of 230% and 350% between 2006–2010 and 2016–2020, respectively. Moreover, the indices showed similar trends throughout the 20-year period, with NDWI having minimum values less than zero in all cases. This implied no surface inundation, although the presence of some wetland vegetation indicated seasonal to semi-permanent soil saturation conditions. A comparative analysis of climate data and remotely sensed indices showed that annual changes of precipitation and evapotranspiration were the main drivers of wetland ecohydrological variations. The findings of the study underscore the relevance of cloud computing artificial intelligence techniques, and particularly the GEE platform, in evaluating wetland ecohydrological dynamics for semi-arid southern African systems which are deteriorating due to the unsustainable use and poor management resulting from limited knowledge about their changes over time.

Wetlands in drylands: Use and conflict dynamics at the human–wildlife interface in Mbire District, Zimbabwe

AbstractWetlands in drylands are important resources for agriculture and wildlife, but competition may result in human–wildlife conflict. We sought to understand conditions under which people and wildlife sharing wetlands in drylands may coexist. We applied track counts in riverine wetlands in the dry and wet season (n = 36 days) using belt transects, focus group discussions (n = 3), key informant interviews (n = 26), a household socio‐economic survey (n = 180) and secondary data analysis to study human–wildlife interactions in a community‐based wildlife management area in Zimbabwe. Twenty‐six wildlife species that used riverine wetlands were identified. High population density and riverine agriculture — with access to cattle and ploughs enabling cultivation of larger fields — limited wildlife access to wetlands. Seasonality, drought, water availability and soil fertility, aggravated by limited alternative livelihood opportunities and lack of political will to control cropping and settlement in wetlands, were drivers of conflict. Hence, models based on population pressure and resource availability are insufficient to inform human–wildlife conflict mitigation. Strategies that undercut rent‐seeking behaviour are needed to enable human–wildlife coexistence. Concerted action among stakeholders including linking wildlife conservation benefits to compliance with wetland‐use regulations, water‐user committees, water provisioning and labour‐saving technologies in uplands, livelihood diversification and incentivised production of drought‐tolerant crops are recommended.

And we thought the Millennium Drought was bad: Assessing climate variability and change impacts on an Australian dryland wetland using an ecohydrologic emulator

During the Millennium Drought in southeast Australia (2001–2009), dryland wetlands experienced widespread ecological deterioration, which highlighted their vulnerability to natural climate variability and the potential effects of drying climate change. Here we use 30-year observed streamflow data (1991–2020) and numerical models to assess the impacts of climate variability and climate change on the Macquarie Marshes (the Marshes), a large floodplain wetland complex in the semi-arid region of New South Wales, Australia. A fast ecohydrologic emulator based on network linear programming with side constraints was developed to simulate the spatial and temporal responses of different wetland vegetation types to water regime. The emulator represents the wetland by a series of inter-connected level-pool reservoirs with the volume-discharge relationship obtained from a calibrated quasi-2d hydrodynamic model. The emulator reproduces daily flows and volume with good accuracy (Nash-Sutcliffe statistic ranging from 0.61 to 0.96) with 1/26,000 of the computational effort. We use the emulator to simulate the potential effects of climatic variability on vegetation by running the model over 30 years of observed data and 1000 statistically representative 30-year streamflow time series, which were generated using a stochastic model calibrated to the gauged flows. The collection of results for all 1000 contemporary simulations indicates the Marshes experience severe conditions 43% (± 18%) of the time in a 30-year period. We then ran an additional 6000 simulations to assess the combined impacts of climate variability and future climate change at the end of the century. For the driest future climates (-60% and -30% reduction in runoff), the Marshes remain in severe condition 89% (± 6%) and 63% (± 16%) of the time, respectively, while no major differences with respect to the contemporary conditions were found for the wetter future. Our results highlight the importance of quantifying the extent and uncertainty in the degradation of these ecosystems due to climate variability and change for informing management decisions.

Soil properties across a hydrological gradient in saladas from northeast Spain: what are the implications for soil carbon stocks, CO2 efflux and microbial communities in a warming world?

Numerous permanent and temporary wetlands occur throughout the world’s drylands. Although characterised by diverse water inundation frequencies, durations and depths, these wetlands in drylands are typically hotspots of biological activity and productivity. The healthy functioning and even existence of many wetlands in drylands, however, is threatened by desiccation resulting from a combination of climate change and human disturbance. Near Alcañiz in arid northeast Spain, three adjacent saladas (playas) with contrasting hydroperiods provide an opportunity to investigate how moisture availability affects their soil carbon (C) stocks, CO2 efflux, and microbial communities. Predicting the impacts of changes in moisture availability on the C cycle in wetlands in drylands is challenging but important because many contain large C stocks and may be significant sources and sinks of greenhouse gases. Frequent inundation and/or near-permanent soil water saturation supports the generation of organic C from a range of different sources. Soil inorganic C was greatest on the driest salada (3.8%) compared to the wetter saladas (3.0% and 2.1%) owing to evaporative concentration and the reaction of CO2 with available Ca2+, Mg2+ and Na+ ions. CO2 efflux was greatest at intermediate moisture levels (142 mg CO2 m−2 h−1), but the spatial and temporal variability in CO2 efflux on salada surfaces is large, demonstrating the need for intensive sampling regimes to provide realistic estimates of their contribution to atmospheric CO2 exchanges. Different microbial community structures also characterise each salada. The saladas near Alcañiz, and many other similar features in northeast Spain, are renowned for their rare and threatened flora and fauna, yet their soil C cycle characteristics and soil microbial communities provide additional reasons to monitor the impacts of climate change and protect these vulnerable environments from further anthropogenic disturbances.

Contextualising sediment trapping and phosphorus removal regulating services: a critical review of the influence of spatial and temporal variability in geomorphic processes in alluvial wetlands in drylands

Contextualising sediment trapping and phosphorus removal regulating services: a critical review of the influence of spatial and temporal variability in geomorphic processes in alluvial wetlands in drylands

Analysis and conceptual geospatial modelling of the intermediary role of wetlands in drylands in post-fire material flux dynamics, Silvermine River catchment, Cape Town

Analysis and conceptual geospatial modelling of the intermediary role of wetlands in drylands in post-fire material flux dynamics, Silvermine River catchment, Cape Town

What drives patchiness in palmiet wetlands?

Wetland communities are shaped by high levels of stress, disturbance and competition. Using South African palmiet wetlands as a case study (Prionium serratum dominated valley-bottom wetlands), we explore whether autogenic or allogenic succession is the dominant process driving community dynamics in valley-bottom wetlands in drylands. Several wetland rehabilitation programmes in South Africa use the dominant wetland species palmiet (P. serratum) as a pioneer to facilitate recolonization. However research is needed on palmiet wetland dynamics and formation to guide these restoration efforts. We explore vegetation patterns by analyzing which environmental parameters drive dominance of palmiet, resulting in the characteristic patchiness of palmiet wetlands, and which plant functional traits account for this. In 20 plots from three palmiet wetlands distributed across the Cape Floristic Region of South Africa, key soil, groundwater and vegetation parameters, as well as community composition were measured. Twenty-two dominant species were selected and 13 functional traits measured. Soil pH and relative groundwater depth were the main environmental parameters driving community assembly in palmiet wetlands. Palmiet-dominated communities were characterized by greater stem diameter, leaf length–width ratio, leaf area and cellulose and lignin concentration compared to fynbos communities. These traits suggest adaptations to disturbances such as fires (thicker stems) and floods (long, thin leaves, flexible shoots and thicker stems). We propose three hypotheses of palmiet wetland development which shed light on palmiet wetland restoration and highlight gaps for future research.

Egg banks in dryland wetlands provide information on the diversity and vulnerability of branchiopod communities along a longitudinal aridity gradient

Egg banks in dryland wetlands provide information on the diversity and vulnerability of branchiopod communities along a longitudinal aridity gradient

Chemical sedimentation as a driver of habitat diversity in dryland wetlands

Freshwater wetlands located in dryland environments are characterised by high evapotranspiration rates and frequent periods of desiccation, which strongly influence the water chemistry and solute budgets of these systems. The transpiration of groundwater, especially by trees, is an important mechanism through which dryland wetlands can lose water. This process can lead to groundwater salinization and the precipitation of substantial quantities of minerals within the soil, the accumulation of which can have profound consequences for wetland structure and function. This paper aims to bring together current knowledge on the processes that result in solute accumulation and chemical sedimentation which assist in maintaining freshwater conditions in many seasonal dryland wetlands. Examples from central and southern Africa, Australia and South America are presented to illustrate the geomorphically diverse settings under which chemical sedimentation can occur, and the importance of these processes for the resilience and longevity of dryland wetlands. We show that the localised development of saline groundwater and subsurface precipitation of minerals within soils can play a key role in creating and maintaining the habitat diversity of dryland wetlands. Wetland vegetation localises the accumulation of deleterious constituents, thereby preventing widespread salinization and playa-lake formation, and thus ensuring that the bulk of the surface water remains fresh. Although such processes remain widely understudied, we suggest that chemical sedimentation could be a common phenomenon in many dryland wetlands and have important implications for the future management of these ecosystems.

Characterising the late Quaternary facies stratigraphy of floodplains in South Africa

AbstractSouth African river floodplains and their alluvial deposits reflect a diversity of geological and geographical drivers. We use a genetic geomorphic classification system originally developed for dryland wetlands to characterise geomorphic processes and potential successions of sedimentary fill for South African floodplains. Using case studies from the literature, we consider differences between alluvial rivers and mixed bedrock-alluvial rivers in the context of macro-scale geomorphic setting, and evaluate the impact of the setting on floodplain persistence and potential as a palaeo-environmental archive. Sedimentary facies associations represented in South African floodplains, including lateral and oblique accretion, channel, channel infill, levee vertical accretion, floodplain vertical accretion and debris flow deposits, are also evaluated.Floodplains of South Africa’s interior are typically mixed bedrock-alluvial as channel beds are set upon or close to bedrock and sediment thickness is limited. By contrast some floodplains in tectonic basin settings have sediment deposits exceeding 30 m in thickness. The resulting rivers are alluvial, and thus able to adjust their width, depth and slope to accommodate changes in discharge and sediment supply. Similarly, coastal floodplain rivers are alluvial due to downcutting during the last glacial maximum and subsequent sedimentary infilling as sea levels rose.When considering the potential of floodplains as palaeoarchives of environmental change, two considerations emerge. First, floodplain stratigraphy is not a response to a single variable due to complex process-form feedbacks. Rather, floodplain stratigraphy is an outcome of both autogenic and allogenic processes. Second, most South African floodplains are zones of sediment recycling, and as such, preservation potential is typically low. Thus, although floodplain settings of the interior may be a few million years old, the sediment within them may be only thousands to tens of thousands of years old. Our review indicates that research has historically focused on meandering river and mixed bedrock-alluvial anabranching river floodplains, while understanding of other floodplain sub-types remains limited.

The future of temporary wetlands in drylands under global change

ABSTRACT The Andalusian International University held a workshop entitled Temporary wetlands’ future in drylands under the projected global change scenario in March 2020 in Baeza, Spain, with 26 participants from 10 countries. The workshop objectives were to promote international cooperation and scientific exchange on the conservation and protection of temporary wetlands. The participants highlighted the extreme conditions that temporary and permanent wetlands, ponds, and shallow lakes are currently facing and predicted a dismal future for these systems due to climate change. To foster a holistic view of these ecosystems, the workshop included wetland watersheds. It was concluded that the main threats are those affecting water quality and quantity as well as egg-seed banks, species population dynamics, and food webs. The inherent characteristics of waterbodies in drylands, including high resilience and resistance to harsh conditions, are already negatively impacted by direct human actions and climate change. Another threat is the time lag between scientific warnings about threats and the social and political concern leading to mitigating actions. Thus, more effective actions to protect and conserve temporary wetlands are essential. Research networks could help stimulate the necessary conservation actions, but the global recession due to the COVID-19 pandemic will pose a challenge as economies are burdened with urgent expenditure. This special issue of the journal Inland Waters is the outcome of the workshop presentations and is composed of the ensuing papers on wetlands in drylands.

Resilience to drought of dryland wetlands threatened by climate change

Dryland wetlands are resilient ecosystems that can adapt to extreme periodic drought–flood episodes. Climate change projections show increased drought severity in drylands that could compromise wetland resilience and reduce important habitat services. These recognized risks have been difficult to evaluate due to our limited capacity to establish comprehensive relationships between flood–drought episodes and vegetation responses at the relevant spatiotemporal scales. We address this issue by integrating detailed spatiotemporal flood–drought simulations with remotely sensed vegetation responses to water regimes in a dryland wetland known for its highly variable inundation. We show that a combination of drought tolerance and dormancy strategies allow wetland vegetation to recover after droughts and recolonize areas invaded by terrestrial species. However, climate change scenarios show widespread degradation during drought and limited recovery after floods. Importantly, the combination of degradation extent and increase in drought duration is critical for the habitat services wetland systems provide for waterbirds and fish.

Patch organization and resilience of dryland wetlands

Dryland wetlands are ecosystems of high ecological importance as they serve as habitat sanctuaries for aquatic and terrestrial biota in areas with very few resources; therefore, the study of such environments is of major importance for the conservation of biodiversity in arid and semi-arid areas. The vegetation organization in these ecosystems is driven by the water regime as the main driver, but local processes like seed banks and soil resources redistribution also play a crucial role in determining the spatial distribution of the vegetation. Assessment of vegetation dynamics and long-term resilience requires the use of realistic models that can integrate the water regime and that can continuously simulate vegetation extent and conditions under flood-drought cycles. Here we study the influence of the water regime as the main driver of the vegetation. We apply a vegetation-modelling framework to compare the performance of a simplified model at the cell scale and a model integrated at a patch scale. Our results show that aggregating the analysis of vegetation dynamics at the patch scale allows for the incorporation of the effects of both local drivers (acting within the patch) as well as the global drivers (acting over the patch as a whole). The water regime acts as a global driver for the vegetation and indirectly affects the local drivers. Our patch scale model successfully captures wetland vegetation dynamics using the water regime as the main driver for representing changes in the vegetation and assessment of the wetland resilience under flood-drought periods.