Semi-arid Landscapes Research Articles

Automated tree crown labeling with 3D radiative transfer modelling achieves human comparable performances for tree segmentation in semi-arid landscapes

Mapping tree crowns in arid or semi-arid areas, which cover around one-third of the Earth’s land surface, is a key methodology towards sustainable management of trees. Recent advances in deep learning have shown promising results for tree crown segmentation. However, a large amount of manually labeled data is still required. We here propose a novel method to delineate tree crowns from high resolution satellite imagery using deep learning trained with automatically generated labels from 3D radiative transfer modeling, intending to reduce human annotation significantly. The methodological steps consist of 1) simulating images with a 3D radiative transfer model, 2) image style transfer learning based on generative adversarial network (GAN) and 3) tree crown segmentation using U-net segmentation model. The delineation performances of the proposed method have been evaluated on a manually annotated dataset consisting of more than 40,000 tree crowns. Our approach, which relies solely on synthetic images, demonstrates high segmentation accuracy, with an F1 score exceeding 0.77 and an Intersection over Union (IoU) above 0.64. Particularly, it achieves impressive accuracy in extracting crown areas (r2 greater than 0.87) and crown densities (r2 greater than 0.72), comparable to that of a trained dataset with human annotations only. In this study, we demonstrated that the integration of a 3D radiative transfer model and GANs for automatically generating training labels can achieve performances comparable to human labeling, and can significantly reduce the time needed for manual labeling in remote sensing segmentation applications.

Survey techniques and impact mitigation for the Endangered northern quoll (Dasyurus hallucatus) in the semi-arid landscapes of the Pilbara

Improvements in survey techniques for threatened species gives quantifiable confidence about their presence or absence at a given location, enhancing our understanding of patterns of distribution and abundance. This is particularly important for legislatively protected threatened species that may be at risk of disturbance. Survey techniques vary in detection confidence, resource investment, and invasive impacts to individuals. We review the appropriate applications of techniques in surveying for the endangered northern quoll (Dasyurus hallucatus), including the effort required to be 95% confident of detecting presence and monitoring change in population trends in the Pilbara bioregion. The outlined protocols indicate best practice for effective and efficient northern quoll monitoring while protecting the welfare of the animals being monitored, and are relevant to Environmental Protection and Biodiversity Conservation Act requirements. We also provide suggestions to mitigate impacts on animals and habitat, and describe future directions and emerging techniques for the monitoring of northern quolls and other endangered species. This information is targeted at those interested in monitoring northern quolls in a field setting, including researchers, environmental consultants, Traditional Owners, and land managers.

Soil response in a Mediterranean forest ecosystem of Southeast Spain following early prescribed burning

The escalation of global warming, high temperatures, and wildfire frequency in dry ecosystems, including semi-arid landscapes, has resulted in increased wildfire regimes, compromising ecosystem resistance and resilience. To mitigate these risks, prescribed burning (PB) is being employed as a preventive measure to modify fuel loads in forest ecosystems. However, fire can also impact soil structure and microbiota, which play critical roles in nutrient cycling, biodiversity conservation, and overall ecosystem functioning. Therefore, understanding post-fire processes is essential for sustainable forest management. However, while previous studies have explored the effects of prescribed fire management on semi-arid soil properties in Mediterranean forest ecosystems, gaps remain in our understanding of its specific impact on the physical structure, chemical composition, and biological activities of soils.In this study, we conducted early spring PB in SE Spain in 2021 and assessed the ecological and temporal effects of PB on semi-arid soils. Soil respiration (SR) measurements using automatic CO2 flow chambers were employed to evaluate microbiota recovery. To examine impacts on soil structure we evaluated physicochemical characteristics, soil hydraulic conductivity (SHC), and soil water repellency (SWR). No significant differences were observed in any of the variables studied after one year. However, immediate effects were detected shortly after the PB. Our research specifically targeted soil structure and microbiota in a semi-arid landscape with poor soils, characterized by slower recovery and potentially fragile ecosystems. These results provide valuable insights for forest management practices, indicating that prescribed fire management strategies in similar ecosystems are unlikely to cause adverse effects on soil health. However, further research is warranted to explore the potential effects of prescribed fire intensity and seasonality. Future studies can focus on investigating these factors to provide more targeted recommendations for effective forest management strategies and wildfire prevention efforts.

Feathers and faith: Sacred groves of semi-arid landscapes hold distinct avian richness and composition in Udaipur district, Rajasthan, India

Sacred groves have long been recognised for their critical role in biodiversity conservation, but research on their importance in avian conservation is limited. We conducted a comprehensive assessment of bird diversity, richness, and abundance within sacred groves and their surrounding areas in the semi-arid landscape of Udaipur, Rajasthan, India. We made 120 point counts (60 sacred groves and 60 random points) to record birds from March 2023 to July 2023. Our results revealed a greater number of bird species (n = 114) within sacred groves than random points (n = 100), including several species of global conservation concern. The species diversity remained consistent, while variations in species richness and abundance was observed. Moreover, we found that the overall composition of birds’ feeding guilds was similar in both groups. We observed noteworthy differences in the abundance of frugivores, granivores, insectivores, and omnivores. Species and guild-level abundance exhibited an even distribution. Species richness in both type of sites predominantly attributed to species turnover. Feeding guilds and bird species had varying associations to environmental variables. Our findings recommend the immediate protection of these sacred areas for bird conservation.

Regulation of surface and sub-surface soil organic carbon sequestration in water-limited landscapes with integration of circular perennial grass buffer strips

Soil organic carbon (SOC) sequestration through innovations in agriculture, including integrating perennial grasses with annual crops, can mitigate climate change. However, integrating circular buffer strips (CBS) of perennial grasses with annual crops in water-limited semi-arid landscapes is a new concept, and how SOC and nitrogen (N) pools respond to CBS and what drives SOC sequestration in the surface and sub-surface depths with CBS integration in typical annual cropping is lacking. Our evaluation of the response of SOC and N fractions under buffer strip grass (BSG), adjacent buffer strip corn (BSC), and continuous conventional corn (CCC) without grass buffer after six years of grass establishment show contrasting trends. The SOC in 0–20 cm depth was 13.1 % greater under BSC than under CCC, while BSG had 49.7–68.2 and 17–29.9 % greater potentially mineralizable carbon (PMC) than CCC and BSC in 40–60 and 60–80 cm, respectively. Mineral-associated organic carbon (MAOC) in 60–80 cm depth was 29.9 % greater under BSG than CCC. Soils under BSC also accumulated 65.6 % more particulate organic carbon (POC) than under CCC in 0–20 cm. While POC contributed to SOC sequestration in surface soils, an increase in MAOC contributed to SOC accumulation in deeper profiles. Integrating buffer strips of perennial grasses enhances soil profile C sequestration in semi-arid agroecosystems through divergent mechanisms in surface and subsurface depths.

The influence of land use and management on the behaviour and persistence of soil organic carbon in a subtropical Ferralsol

Abstract. A substantial carbon (C) debt has been accrued due to long-term cropping for global food production emitting carbon dioxide from soil. However, the factors regulating the persistence of soil organic C (SOC) remain unclear, with this hindering our ability to develop effective land management strategies to sequester organic C in soil. Using a Ferralsol from semi-arid subtropical Australia, alteration of bulk C contents and fractions due to long-term land use change (up to 72 years) was examined with a focus on understanding whether SOC lost due to cropping could be restored by subsequent conversion back to pasture or plantation. It was found that use of soil from cropping for 72 years resulted in the loss of >70 % of both C and N contents. Although conversion of cropped soil to pasture or plantation for up to 39 years resulted in an increase in both C and N, the C contents of all soil fractions were not restored to the original values observed under remnant vegetation. The loss of C with cropping was most pronounced from the particulate organic matter fraction, whilst in contrast, the portion of the C that bound strongly to the soil mineral particles (i.e. the mineral-associated fraction) was most resilient. Indeed, aliphatic C was enriched in the fine fraction of mineral-associated organic matter (<53 µm). Our findings were further confirmed using Synchrotron-based micro-spectroscopic analyses of intact microaggregates, which highlighted that binding of C to soil mineral particles is critical to SOC persistence in disturbed soil. The results of the present study extend our conceptual understanding of C dynamics and behaviour at the fine scale where C is stabilized and accrued, but it is clear that restoring C in soils in semi-arid landscapes of subtropical regions poses a challenge.

Household water insecurity experience in the Upper West Region of Ghana: Insights for effective water resource management

The global community is not on track to achieve Sustainable Development Goal 6 (SDG 6) by 2030. Many low- and middle-income countries like Ghana still struggle with water insecurity. In semi-arid regions like Ghana’s Upper West, climate change has worsened water insecurity, leading to health and livelihood consequences. In UWR, limited studies have explored water insecurity in rural areas. This study fills a knowledge gap by investigating the determinants of water insecurity in Ghana’s Upper West Region (UWR) from a political ecology of health (PEH) perspective. It comprehensively explores the interplay of social, economic, political, environmental, and health-related factors contributing to water insecurity in the UWR. The results from binary logistic regression show that households in the wealthier category (OR = 0.475, p<0.05) and those that spent less than thirty minutes on a roundtrip to fetch water (OR = 0.474, p<0.01) were less likely to experience water insecurity. On the other hand, households that did not use rainwater harvesting methods (OR = 2.117, p<0.01), had to travel over a kilometer to access water (OR = 3.249, p<0.01), had inadequate water storage systems (OR = 2.290, p<0.001), did not treat their water (OR = 2.601, p<0.001), were exposed to water-induced infections (OR = 3.473, p<0.001), did not receive any water, hygiene, and sanitation education (OR = 2.575, p<0.01), and faced water scarcity during the dry season (OR = 2.340, p<0.001) were at a higher risk of experiencing water insecurity. To mitigate the risks of water insecurity and adverse health impacts, policymakers and practitioners must work together to educate households on effective water conservation, storage, and treatment techniques. It is recommended that households harvest rainwater as a coping strategy, construct appropriate storage systems, and treat their water. Communal self-help water investments should be encouraged and supported. Given the significant aquifers and semi-arid landscape of the UWR, investing in groundwater development should be a top priority.

Soil Properties and Stoichiometry as Influenced by Land Use, Enclosures and Seasonality in a Semi-arid Dryland in Kenya

Agropastoralism and nomadic pastoralism constitute the main land use systems in semi-arid drylands in Kenya. However, limited studies have investigated how land use and management practices and seasonality affect soil properties that alter C, N, and P biogeochemical cycling in African drylands systems. Thus, this study was conducted to determine effects of: (1) sedentary agropastoral land-use system (SAL), (2) semi-nomadic pastoral land-use system (SNL)), (3) pasture enclosures and (4) seasonality on selected soil chemical properties and total C, N, and P stoichiometry in a semi-arid landscape in Kenya. Land use, enclosures, and seasonality affected chemical properties of soils and C, N, and P stoichiometry. Generally, Na, K, Ca, Mg and cation exchange capacity were higher in the dry than wet period. Soil C:N ratios were less than 5, while N:P and C:P ratios were 5–56 and 16–177, respectively. However, ratios of C:N, N:P and C:P were significantly higher in SNL than SAL. The C:P and N:P ratios in both land use systems were highly correlated (r2 > 0.70). During the wet season, C:N ratios of soils were higher inside enclosures in both land uses. Higher soil N:P and C:P ratios were observed during dry compared to wet seasons. The N:P and C:P ratios of soils were higher inside and outside enclosures in SAL and SNL, respectively. Land use, enclosures and seasonality exhibited different effects on chemical properties of soils and C:N:P stoichiometry ratios. Perennial vegetation cover in enclosures has a great potential to enhance soil health necessary to support pastoral land-use systems in semi-arid African drylands.

Structural heterogeneity predicts ecological resistance and resilience to wildfire in arid shrublands

ContextDynamic feedbacks between physical structure and ecological function drive ecosystem productivity, resilience, and biodiversity maintenance. Detailed maps of canopy structure enable comprehensive evaluations of structure–function relationships. However, these relationships are scale-dependent, and identifying relevant spatial scales to link structure to function remains challenging.ObjectivesWe identified optimal scales to relate structure heterogeneity to ecological resistance, measured as the impacts of wildfire on canopy structure, and ecological resilience, measured as native shrub recruitment. We further investigated whether structural heterogeneity can aid spatial predictions of shrub recruitment.MethodsUsing high-resolution imagery from unoccupied aerial systems (UAS), we mapped structural heterogeneity across ten semi-arid landscapes, undergoing a disturbance-mediated regime shift from native shrubland to dominance by invasive annual grasses. We then applied wavelet analysis to decompose structural heterogeneity into discrete scales and related these scales to ecological metrics of resilience and resistance.ResultsWe found strong indicators of scale dependence in the tested relationships. Wildfire effects were most prominent at a single scale of structural heterogeneity (2.34 m), while the abundance of shrub recruits was sensitive to structural heterogeneity at a range of scales, from 0.07 – 2.34 m. Structural heterogeneity enabled out-of-site predictions of shrub recruitment (R2 = 0.55). The best-performing predictive model included structural heterogeneity metrics across multiple scales.ConclusionsOur results demonstrate that identifying structure–function relationships requires analyses that explicitly account for spatial scale. As high-resolution imagery enables spatially extensive maps of canopy heterogeneity, models for scale dependence will aid our understanding of resilience mechanisms in imperiled arid ecosystems.

Mapping sub-surface distribution of soil organic carbon stocks in South Africa's arid and semi-arid landscapes: Implications for land management and climate change mitigation

Soil organic carbon (SOC) stocks are critical for land management strategies and climate change mitigation. However, understanding SOC distribution in South Africa's arid and semi-arid regions remains a challenge due to data limitations, and the complex spatial and sub-surface variability in SOC stocks driven by desertification and land degradation. Thus, to support soil and land-use management practices as well as advance climate change mitigation efforts, there is an urgent need to provide more precise SOC stock estimates within South Africa's arid and semi-arid regions. Hence, this study adopted remote-sensing approaches to determine the spatial sub-surface distribution of SOC stocks and the influence of environmental co-variates at four soil depths (i.e., 0-30 cm, 30-60 cm, 60-100 cm, and 100-200 cm). Using two regression-based algorithms, i.e., Extreme Gradient Boosting (XGBoost) and Random Forest (RF), the study found the former (RMSE values ranging from 7.12 t/ha to 29.55 t/ha) to be a superior predictor of SOC in comparison to the latter (RMSE values ranging from 7.36 t/ha to 31.10 t/ha). Nonetheless, both models achieved satisfactory accuracy (R2 ≥ 0.52) for regional-scale SOC predictions at the studied soil depths. Thereafter, using a variable importance analysis, the study demonstrated the influence of climatic variables like rainfall and temperature on SOC stocks at different depths. Furthermore, the study revealed significant spatial variability in SOC stocks, and an increase in SOC stocks with soil depth. Overall, these findings enhance the understanding of SOC dynamics in South Africa's arid and semi-arid landscapes and emphasizes the importance of considering site specific topo-climatic characteristics for sustainable land management and climate change mitigation. Furthermore, the study offers valuable insights into sub-surface SOC distribution, crucial for informing carbon sequestration strategies, guiding land management practices, and informing environmental policies within arid and semi-arid environments.

Changes in submerged macrophyte diversity, coverage and biomass in a biosphere reserve site after 20 years: A plea for conservation efforts

The conservation of submerged vegetation is crucial in the functioning of aquatic ecosystems. We have assessed, by means of subaquatic quantitative sampling transects, the current status of the hydrophytic flora in 14 lakes in the Lagunas de Ruidera Natural Park, a Biosphere Reserve site in central Spain, surrounded by a semi-arid landscape. The conforming lakes have endured several anthropic pressures for decades (e.g., eutrophication, land-use changes, etc.). By comparing the current with the former status (20 years ago) of hydrophytes in the natural park, substantial negative (species richness loss, decrease in submerged meadow coverage, particularly in the upstream lakes) and positive (natural recovery of meadows after the cut-off of sudden disturbances caused by point pollution sources, improving of trophic state in some lakes, no presence of exotic hydrophytes) changes in the lakes were noticed. We have analyzed that the disappearance of all the hydrophyte (mainly charophytes) stands would represent the loss of ecosystem services. For example, up to 70 t CH4 might be released from the charophyte detritus, an internal pool of phosphorus (as high as 1400 mgP/m2) stored in the charophytes stands could be liberated. Some lakes require special measures, but overall, to preserve this lake complex, and other similar ones, we propose to study, in detail, the causes of submerged vegetation deterioration (focusing on the presence of pesticides –in water and sediments-, and other reasons) to assess the ecological risks, to protect the groundwater resources, preventing the lakes from receiving surficial point and non-point sources of pollution.

Monitoring of Plant Ecological Units Cover Dynamics in a Semiarid Landscape from Past to Future Using Multi-Layer Perceptron and Markov Chain Model

Anthropogenic activities and natural disturbances cause changes in natural ecosystems, leading to altered Plant Ecological Units (PEUs). Despite a long history of land use and land cover change detection, the creation of change detection maps of PEUs remains problematic, especially in arid and semiarid landscape. This study aimed to determine and describe the changes in PEUs patterns in the past and present, and also predict and monitor future PEUs dynamics using the multi-layer perceptron-Markov chain (MLP-MC) model in a semiarid landscape in Central Zagros, Iran. Analysis of PEUs classification maps formed the basis for the identification of the main drivers in PEUs changes. First, an optimal time-series dataset of Landsat images were selected to derive PEUs classification maps in three periods, each separated by 16 years. Then, PEUs multi-temporal maps classified for period 1 (years 1986–1988) period 2 (years 2002–2004), and period 3 (years 2018–2020) were employed to analyze and predict PEUs dynamics. The dominant transitions were identified, and the transition potential was determined by developing twelve sub-models in the final change prediction process. Transitions were modeled using a Multi-Layer Perceptron (MLP) algorithm. To predict the PEU map for period 3, two PEUs classification maps of period 1 and period 2 were used using the MLP-MC method. The classified map and the predicted map of period 3 were used to evaluate and validate the predicted results. Finally, based on the results, transitions of future PEUs were predicted for the year 2036. The MLP-MC model proved to be a powerful model that can predict future PEUs dynamics that are the result of current human and managerial activities. The findings of this study demonstrate that the impact of anthropogenic processes and management activities will become visible in the natural environment and ecosystem in less than a decade.

Seasonal Hair Glucocorticoid Fluctuations in Wild Mice (Phyllotis darwini) within a Semi-Arid Landscape in North-Central Chile.

Mammals in drylands face environmental challenges exacerbated by climate change. Currently, human activity significantly impacts these environments, and its effects on the energy demands experienced by individuals have not yet been determined. Energy demand in organisms is managed through elevations in glucocorticoid levels, which also vary with developmental and health states. Here, we assessed how anthropization, individual characteristics, and seasonality influence hair glucocorticoid concentration in the Darwin's leaf-eared mouse (Phyllotis darwini) inhabiting two areas with contrasting anthropogenic intervention in a semi-arid ecosystem of northern Chile. Hair samples were collected (n = 199) to quantify hair corticosterone concentration (HCC) using enzyme immunoassays; additionally, sex, body condition, and ectoparasite load were recorded. There were no differences in HCC between anthropized areas and areas protected from human disturbance; however, higher concentrations were recorded in females, and seasonal fluctuations were experienced by males. The results indicate that animals inhabiting semi-arid ecosystems are differentially stressed depending on their sex. Additionally, sex and season have a greater impact on corticosterone concentration than anthropogenic perturbation, possibly including temporal factors, precipitation, and primary production. The influence of sex and seasonality on HCC in P. darwini make it necessary to include these variables in future stress assessments of this species.

Vegetation, fuels, and fire-behavior responses to linear fuel-break treatments in and around burned sagebrush steppe: are we breaking the grass-fire cycle?

BackgroundLinear fuel breaks are being implemented to moderate fire behavior and improve wildfire containment in semiarid landscapes such as the sagebrush steppe of North America, where extensive losses in perennial vegetation and ecosystem functioning are resulting from invasion by exotic annual grasses (EAGs) that foster large and recurrent wildfires. However, fuel-break construction can also pose EAG invasion risks, which must be weighed against the intended fire-moderation benefits of the treatments. We investigated how shrub reductions (mowing, cutting), pre-emergent EAG-herbicides, and/or drill seedings of fire-resistant perennial bunchgrasses (PBGs) recently applied to create a large fuel-break system affected native and exotic plant abundances and their associated fuel loading and predicted fire behavior.ResultsIn heavily EAG-invaded areas, herbicides reduced EAG and total herbaceous cover without affecting PBGs for 2–3 years and reduced predicted fire behavior for 1 year (from the Fuel Characteristic Classification System). However, surviving post-herbicide EAG cover was still > 30%, which was sufficient fuel to exceed the conventional 1.2-m-flame length (FL) threshold for attempting wildfire suppression with hand tools. In less invaded shrubland, shrub reduction treatments largely reduced shrub cover and height by ~ half without increasing EAGs, but then redistributed the wood to ground level and increased total herbaceous cover. Herbicides and/or drill seeding after shrub reductions did not affect EAG cover, although drill seedings increased PBG cover and exotic forbs (e.g., Russian thistle). Fire behavior was predicted to be moderated in only one of the many yearly observations of the various shrub-reduction treatment combinations. Over all treatments and years, FLs were predicted to exceed 1.2 m in 13% of simulations under average (11 km h−1) or high (47 km h−1) wind speed conditions and exceed the 3.4-m threshold for uncontrollable fire in 11% of simulations under high-wind speeds only.ConclusionsPredicted fire-moderation benefits over the first 4 years of fuel break implementation were modest and variable, but, generally, increases in EAGs and their associated fire risks were not observed. Nonetheless, ancillary evidence from shrublands would suggest that treatment-induced shifts from shrub to herbaceous fuel dominance are expected to improve conditions for active fire suppression in ways not readily represented in available fire models.

Comprehensive analysis of land use and cover dynamics in djibouti using machine learning technique: A multi-temporal assessment from 1990 to 2023

Understanding land use and land cover (LULC) dynamics in semi-arid regions is vital for unraveling complex environmental processes and resource management. This study delves into the intricate interplay of land patterns and resource dynamics, offering indispensable insights into the environmental repercussions of these changes. The study aims to quantify land use categories in Djibouti's semi-desert region using remote sensing. It analyzes temporal changes and evaluates Random Forest (RF) algorithms for land use classification. Through meticulous quantification and comprehensive temporal analysis, the research contributes significantly to remote sensing and environmental science by enhancing understanding of land use dynamics and informing sustainable land management practices. Leveraging machine learning supervised classification on the Google Earth Engine (GEE) platform using Landsat data spanning four time periods (1990, 2002, 2012, and 2023), alongside spectral indices and Digital Elevation Model (DEM) data, our study achieves unprecedented insights. Our findings reveal a significant landscape transformation, delineating seven major land cover classes: mangroves, bushes, farmland, built-up areas, water bodies, barren land, and salt plains. With overall accuracy ranging from 89 % to 95 %, our assessments demonstrate significant changes in land use types over the studied period. Notably, mangroves, bushes, farmland, and salt areas witnessed declines, while built-up areas, water bodies, and barren lands expanded. This research underscores the pivotal role of remote sensing in monitoring long-term land use changes and their ecological impacts. By harnessing technological advancements, our study empowers stakeholders to make informed decisions for sustainable resource management and environmental conservation in semi-arid landscapes.

Flood-irrigated agriculture mediates climate-induced wetland scarcity for summering sandhill cranes in western North America.

Information about species distributions is lacking in many regions of the world, forcing resource managers to answer complex ecological questions with incomplete data. Information gaps are compounded by climate change, driving ecological bottlenecks that can act as new demographic constraints on fauna. Here, we construct greater sandhill crane (Antigone canadensis tabida) summering range in western North America using movement data from 120 GPS-tagged individuals to determine how landscape composition shaped their distributions. Landscape variables developed from remotely sensed data were combined with bird locations to model distribution probabilities. Additionally, land-use and ownership were summarized within summer range as a measure of general bird use. Wetland variables identified as important predictors of bird distributions were evaluated in a post hoc analysis to measure long-term (1984-2022) effects of climate-driven surface water drying. Wetlands and associated agricultural practices accounted for 1.2% of summer range but were key predictors of occurrence. Bird distributions were structured by riparian floodplains that concentrated wetlands, and flood-irrigated agriculture in otherwise arid and semi-arid landscapes. Findings highlighted the role of private lands in greater sandhill crane ecology as they accounted for 78% of predicted distributions. Wetland drying observed in portions of the range from 1984 to 2022 represented an emerging ecological bottleneck that could limit future greater sandhill crane summer range. Study outcomes provide novel insight into the significance of ecosystem services provided by flood-irrigated agriculture that supported nearly 60% of wetland resources used by birds. Findings suggest greater sandhill cranes function as a surrogate species for agroecology and climate change adaptation strategies seeking to reduce agricultural water use through improved efficiency while also maintaining distinct flood-irrigation practices supporting greater sandhill cranes and other wetland-dependent wildlife. We make our wetland and sandhill crane summering distributions available as interactive web-based mapping tools to inform conservation design.

Social learning to promote forest restoration in a semi-arid landscape in North Africa

Forest restoration is a suitable tool to mitigate land degradation and enhance the supply of vital goods and services. Social participation in forest restoration has gained increasing interest. Yet, the impact of participation on people's perception of ecological restoration and the restoration process has barely been addressed despite its relevance for the long-term success of restoration actions. We assessed mutual learning of different stakeholder groups in a ten-year demonstration project, and its potential to foster continued participatory forest restoration in Beni Boufrah valley, a semiarid area located in North Morocco. We performed face-to-face interviews to assess post-restoration individual learning for a subset of 15 highly engaged stakeholders using five components of social learning: reciprocal determinism, self-reflective capability, expectations, self-regulation and locus of control. Furthermore, we organized a workshop to assess collective learning in the study area. The lessons learnt by the project team was described using monitoring vegetation measurements, field visits and meetings, and stakeholder recommendations. Two thirds of the stakeholders showed an increasing awareness of the reciprocal relationship between people and the environment, while recognizing the inappropriateness of current behaviors and practices. Farmers showed continuous mistrust towards the Forestry Agency which justifies the need for more innovative approaches to resolve persistent conflicts, integrate forest and agricultural interventions and establish new mechanisms for economic motivation. Stakeholders acquired theoretical and practical concepts on forest restoration, but self-initiated activities were scarce and reinforcement of environmental awareness is still needed. There was a high impact of drought on seedling survival and growth along with a decrease in stakeholder engagement over the years. We could identify and implement a series of practical corrective measures, namely participatory re-planting, plot fencing, establishment of a local monitoring committee, and raising awareness activities. Such participatory implementation of corrective measures may enhance the credibility of the restoration process and it can be further tested in similar semiarid areas of North Africa even at a larger scale.

An environmental flow to an ephemeral creek increases the input of carbon and nutrients to a downstream receiving river

Although intermittent and ephemeral rivers lack surface flow for part of the year, they provide vital refuges for biota in otherwise dry semi-arid and arid landscapes. The hydrology of many such rivers has been altered due to river regulation and climate change. Environmental flows can be delivered to address the negative impacts of regulated flows, however there is limited knowledge of how dry ephemeral ecosystems respond following environmental flows. This study examined changes in water quality of the ephemeral Thule Creek in the southern Murray-Darling Basin, Australia, following delivery of environmental water from an irrigation canal. We also examined how the environmental flow influenced water quality of Wakool River that receives inflows from Thule Creek. Six sites in Thule Creek, three in Wakool River, and one in Yarraman irrigation channel (source water) were monitored for dissolved organic carbon (DOC), nutrients and dissolved oxygen (DO) once per week over 15 weeks from October 2019 to January 2020. The environmental flow resulted in high DOC concentrations (4.4–76 mg/L). Although low DO levels at sites in Thule Creek were recorded on some dates below the threshold for fish stress (< 4 mg/L) there were no fish kills observed during the environmental flow. The carbon-rich and nutrient-rich water (DOC >10 mg/L, total phosphorus up to 94 μg/L, total nitrogen up to 1,125 μg/L) was detected in the Wakool River downstream of Thule Creek confluence compared to the Wakool River upstream of Thule Creek confluence (DOC 6.6 mg/L, total phosphorus up to 64 μg/L, total nitrogen up to 805 μg/L) during the period when the environmental flow in Thule Creek was connected with the Wakool River. This research provides an example of how irrigation canal networks can be used to deliver environmental water to an ephemeral river to maintain refuges and contribute to the productivity of a receiving river further downstream. Careful management of the timing, volume and duration of environmental flows in arid or semi-arid landscapes is needed to avoid the development of poor water quality during, or following, the delivery of environmental water.

Seasonal dynamics and spatial patterns of soil moisture in a loess catchment

Abstract. The spatial and seasonal patterns in soil moisture and the processes controlling them in semi-arid landscapes are not well understood. Loess landscapes minimize any confounding effects of variation in soil characteristics and are thus ideal for studying topographic influences on soil moisture in drylands. In this study, volumetric soil moisture was monitored monthly for 5.5 years at 20 cm intervals between the surface and 5 m depth at 89 sites across a small (0.43 km2) catchment on the Chinese Loess Plateau. The median soil moisture was computed for each month and depth for each monitoring site as a measure of the typical soil moisture conditions. Seasonal changes in soil moisture were mainly concentrated in the shallow (0–100 cm) soil, with a clear seasonal separation between wet conditions in October–March and dry conditions in May–July, even though precipitation is highest in July–August. Soil moisture was higher on the northwest-facing slopes due to increased drying from solar radiation on the southeast-facing slopes. This effect of slope aspect was greater between October and March, when the zenith angle of the sun was lower and the aspect-dependent difference in solar radiation reaching the surface was larger. The wetter, northwest-facing slopes were also characterized by larger annual soil moisture storage changes. Soil texture was nearly uniform across both slopes, and soil moisture was not correlated with the topographic wetness index, suggesting that variations in evapotranspiration dominated the spatial pattern of soil moisture in shallow soils under both wet and dry conditions. Water balance calculations indicate that over 90 % of the annual precipitation was seasonally cycled in the soil between 0 and 300 cm, suggesting that only a minor fraction infiltrates to groundwater and becomes streamflow. Our findings may be broadly applicable to loess regions with monsoonal climates and may have practical implications for catchment-scale hydrologic modeling and the design of soil moisture monitoring networks.

Quantifying climate change impacts on future water resources and salinity transport in a high semi-arid watershed

High salinity mobilization and movement from salt-laden deposits in semi-arid landscapes impair soils and water resources worldwide. Semi-arid regions worldwide are expected to experience rising temperatures and lower precipitation, impacting water supply and spatio-temporal patterns of salinity loads and affecting downstream water quality. This study quantifies the impact of future climate on hydrologic fluxes and salt loads in the Gunnison River Watershed (GRW) (14,608 km2), Colorado, using the APEX-MODFLOW-Salt hydro-chemical watershed model and three different CMIP5 climate models projection downscaled by Multivariate Adaptive Constructed Analogs (MACA) for the period 2020–2099. The APEX-MODFLOW-Salt model accounts for the reactive transport of major salt ions (SO42−, Cl−, CO32−, HCO3−, Ca2+, Na+, Mg2+, and K+) to streams via surface runoff, rainfall erosional runoff, soil lateral flow, quick return flow and groundwater-stream exchange. Model results are analyzed for spatial and temporal trends in water yield and salt loading pathways. Although streamflow is primarily derived from surface runoff (65%), the predominant source of salt loads is the aquifer (73%) due to elevated concentrations of groundwater salt. Annual salt loading from the watershed is 582 Mkg, approximately 10% of the salt load in the Colorado River measured at Lee's Ferry, AZ. For future climate scenarios, annual salt loads from the watershed increased between 4.1% and 9.6% from the historical period due to increased salt loading from groundwater and quick return flow. From the results, applying the APEX-MODFLOW-Salt model with downscaled future climate forcings can be a helpful modeling framework for investigating hydrology and salt mobilization, transport, and export in historical and predictive settings for salt-affected watersheds.