Dryland Communities Research Articles

Utilisation of Anthropogenic Landscapes by Bird Communities in West African Drylands

Utilisation of Anthropogenic Landscapes by Bird Communities in West African Drylands

Geomorphological and Sedimentological Rationale for Staged Sand Dam Construction

ABSTRACTStream sediment transport results from a convolution of climate, weather, geology, topography, biology, and human influence. In addition to providing water and food security for rural dryland communities, sand dams—small weirs designed to trap only the coarse fractions of transported sediments in seasonal and ephemeral streams—highlight many complexities of geomorphological dynamics. Sand dams store water in interstitial riverbed pores and the size of deposited sediment particles largely determines the recoverability of stored water: Fine materials limit transmission and provide lower volumetric yield. In this study, we seek to identify a practical method for evaluating the theoretical effect of staged sand dam crest construction on key sediment‐trapping processes for a proposed dam site. We argue that the Rouse number provides a useful criterion for identifying regimes where the target material grades are trapped. These ideas were tested using sediment data collected in Kenya and US Army Corps of Engineers River Analysis System numerical simulations to evaluate the sensitivity of sedimentation processes to crest height. We show that constructing sand dams in stages results in more targeted trapping of coarse material. Sedimentation is shown to be more sensitive to variation in crest height than the flood hydrograph, especially when a dam's crest height is small. By introducing a method to assess the necessity and inform design of staged crest construction based on local flow dynamics, this study offers a framework for optimising sand dam performance in data‐scarce environments. This approach provides a means to balance construction costs with expected benefits, enhancing the sustainability and functionality of sand dams in arid and semi‐arid regions.

A Study of Gender Perspectives on Farmers' Livelihood Resources in a Dryland Farming Community of Lombok Island, Indonesia

Aim: A case study on Lombok Island, Indonesia, examined livelihood resources among rain-fed rice farmers from a gender perspective. Study Design: Using a descriptive approach, the study purposely selected dryland and rain-fed farming communities reliant on agriculture. Place and Duration of the Study: The study was conducted in the southern part of Lombok Island between December 2023 to January 2024. Methodology: Data from 30 respondents (15 male, 15 female farmers) assessed livelihood resources across human, natural, financial, social, and physical aspects. Analysis employed categorical techniques and mode calculations. Results: Male farmers predominated in managing human resources and natural resources such as land and water ownership. Females excelled in household water use, technology adoption, and accessing financial aid. Both genders managed income and savings similarly, with males showing greater agricultural knowledge and communication skills. Conclusion: These insights underscore the nuanced gender dynamics in resource management and highlight the need for gender-responsive policies to foster sustainable livelihoods in vulnerable dryland communities.

Over-reliance on water infrastructure can hinder climate resilience in pastoral drylands

Extreme droughts are affecting millions of livestock farmers in sub-Saharan Africa, causing water shortages, famines, migration and fatalities. The construction of new small water infrastructures (SWIs), such as deep wells and boreholes, is increasingly supported by climate resilience programmes of non-governmental organizations and national governments to improve water availability for agro-pastoralists, especially as an emergency response to extreme droughts. Although the short-term benefits of SWI are clear, their potential cumulative impact and their long-term effects on the resilience of dryland communities remain unclear. Here, building on in-depth anthropological literature from five key African drylands, we model post-drought pastoralists’ dynamics related to SWI. We show that while developing new SWI releases water shortages in the short term, it can erode traditional adaptation practices without adequate governance. We further illustrate how our model captures early quantitative signals of resilience loss in dryland Angola. This indicates that poorly governed water development in African drylands can be a limiting factor for the long-term resilience of pastoral communities facing a range of social, demographic, economic and climate challenges.

Assessing key behavioural theories of drought risk adaptation: Evidence from rural Kenya.

The Horn of Africa Drylands are increasingly experiencing severe droughts, which impose a threat on traditional livelihood strategies. Understanding adaptation behavior in rural communities is key to helping reduce the impact of these droughts. We investigate adaptation behavior by assessing four established economic and social psychological theories on decision making under risk: expected utility theory (EUT), rank dependent utility theory (RDU), protection motivation theory (PMT), and theory of planned behavior (PMT). To measure adaptation behavior and the theory constructs, we conducted a household survey in Kenya (N=502). Regression analysis shows that the economic theories (EUT and RDU) have the best fit for our data. Risk and time preferences are found to play an important role in adaptation decisions. An analysis of differences in decision making for distinct types of adaptation measures shows that risk averse (agro-)pastoralists are more likely to implement adaptation measures that are adjustments to their current livelihood practices, and less willing to invest in adaptation measures that require a shift to other livelihood activities. Moreover, we find significant effects for elements of the social psychological theories (PMT and TPB). A person's belief in their own ability to implement an adaptation measure (perceived self-efficacy) and adaptation by family and friends are important factors in explaining adaptation decisions. Finally, we find that the type of adaptation measures that people implement is influenced by, among others, gender, education level, access to financial resources, and access to government support or aid. Our analysis gives insights into the drivers of individual adaptation decisions, which can enhance policies promoting adaptation of dryland communities.

Restoring Food Systems with Nutritious Native Plants: Experiences from the African Drylands.

Twenty-seven African countries have committed to restore more than 100 million hectares of degraded land by 2030 as part of the African Forest Landscape Restoration Initiative (AFR100). In addition, for the same period of time, the African-led Great Green Wall initiative seeks to restore 100 million hectares of degraded agro-sylvo-pastoral lands in the Sahel. The current UN Decade on Ecosystem Restoration (2021-2030) moreover marks an unprecedented opportunity to shape future landscapes, and forge more biodiverse and nutritious food systems. Yet most large-scale restoration actions continue to be largely isolated from socioeconomic challenges facing dryland communities, not least food security and acute malnutrition. Such isolations contribute to low restoration successes and outcomes in Africa's drylands. At the same time, international interventions aimed at improving acute malnutrition in the drylands have not adequately considered the agriculture-nutrition linkages, particularly "pre-farm gate"-including consumption pathways which optimize the use of native plant diversity. This article identifies priority action areas emerging from experiences over 5 years of restoration activities carried out in the Sahel through Food and Agriculture Organization's (FAO) Action Against Desertification Programme supporting the implementation of Africa's Great Green Wall. These actions aim to inform development and humanitarian interventions on the ground to render restoration interventions nutrition-sensitive and hence more effective in practice. Recognizing the symbiotic relationship between landscapes and livelihoods, FAO developed a blueprint for large-scale restoration that combines biophysical and socioeconomic aspects for the benefit of rural communities. The approach builds climate and nutritional resilience into its restoration interventions as a preventative approach to reverse land degradation and ultimately improve livelihoods, food security, and nutrition. FAO's experience demonstrated that what is planted and when has the potential to not only significantly improve biodiversity and reverse land degradation, but also positively influence nutrition outcomes. Future interventions in the drylands must involve joint efforts between nutritionists and natural resource managem prove both human and planetary health.

Modeling‐based performance assessment of an indigenous macro‐catchment water harvesting technique (Marab) in the Jordanian Badia

AbstractWater resources management is fundamental for rural communities in drylands, where water harvesting technologies (WHT) can be used for intercepting surface runoff and storing water in soils. The so‐called “Marab” WHT was initially developed by Middle Eastern agro‐pastoralists that reside or commute in semi‐arid and arid rangelands. The Marab WHT is a macro‐catchment measure consisting of earth dams and stone spillways along the contours of a lowland depression or floodplain. Dependent on the local context (i.e., climate, soil, management, etc.), the established Marabs show highly variable effectiveness and little scientific evidence is supporting the scaling out of the technology. This study aims at filling the knowledge gap on the Marab performance in different environments by simulating its hydro‐agrological effects for different soils and climatic conditions using the AquaCrop model. A case study performed for a Jordanian Marab over three seasons (2019–2022) confirms its huge improvement potential for barley production. Through Marab‐based farming, barley production reached 8.37 t ha−1on average, versus highly variable 0.34 t ha−1without the WHT. The simulation‐based assessment of soil textures identified that silty soils have the largest potential for producing up to 9.25 t ha−1barley, compared to 6.60 t ha−1produced in clay soils. Assessing different climate scenarios, a slight increase in daily average temperatures (+0.5°C) led to a considerable production decline of 4%–8%, while a significant reduction of precipitation (−20%) decreased biomass production by a similar rate (4%–10%). This underlines the robustness of the “Marab” WHT to rainfall amount variation. However, simulations also highlight the sensitivity of timing and frequency of flood events: removing the last and the first flood event reduced biomass production by approximately 50% and 80%, respectively, while the barley fails to develop if both events were suppressed.

Effects of Long-term Fertilization on Soil Microbial Diversity and Community Structure in the Agro-pastoral Ecotone

To explore the effects of different long-term fertilization treatments on soil microbial diversity and community structure in the drylands of an agro-pastoral ecotone, a long-term fertilization experiment at the Inner Mongolia cultivated land conservation science observation and experiment station, Ministry of Agriculture, and rural areas was taken as the research object. Four treatments, including no fertilizer (CK), single nitrogen fertilizer (NF), single chemical fertilizer (CF), and the combined application of organic manure and chemical fertilizer (CFM), were selected for the collection of 0-10 cm and 10-20 cm soil at potato maturity 16 years after the experiment (2019). High-throughput sequencing technology was used to assess the soil bacterial and fungal communities to explore the effects of different fertilization measures on soil quality from the perspective of microorganisms, and the partial least squares path model (PLS-PM) was used to reveal the key environmental driving factors of soil microbial community alternation and crop yield improvement in dryland during fertilization mode transformation. The results showed that:① the CF and CFM treatments significantly improved soil fertility, but the effect of the latter was significantly better than that of the former. Soil available nitrogen, available phosphorus, and available potassium in the CFM treatment increased by 131.9%-174.7%, 216.9%-283.3%, and 103.3%-109.3%, respectively, and organic matter and total nitrogen content also increased significantly. The CF treatment still maintained a high soil pH, whereas the NF treatment significantly decreased soil pH and had little effect in improving soil fertility. ② Compared with that under CK, the NF treatment significantly reduced the soil bacterial Chao1 and Shannon index, and the CFM treatment significantly increased the soil bacterial species richness, Chao1 index, and soil fungal Shannon index, whereas soil bacterial and fungal diversity in the CF treatment did not reach a significant difference level with CK. ③ The soil microbial community composition at 0-10 cm and 10-20 cm was similar. The CFM treatment increased the relative abundance of soil beneficial bacteria and decreased the relative abundance of pathogenic bacteria. The relative abundance of dominant bacteria such as Proteobacteria, Bacteroidetes, and Gemmatimonadetes increased. The relative abundances of Actinobacteria, Ascomycota, and Basidiomycota were decreased, whereas the NF and CF treatments showed the opposite trend. ④ PLS-PM analysis showed that with the gradual change in fertilization mode from CK→NF→CF→CFM, the driving factors affecting microbial community succession and yield increase were also changed from soil pH→soil NPK content→soil pH, SOM, and NPK content. In general, long-term fertilization had significant effects on soil chemical properties and microbial communities in drylands in the agro-pastoral ecotone. As the optimal fertilization choice, CFM was significantly better than NF and CF in improving soil fertility and inhibiting the growth of pathogenic microorganisms. The number of pathogens in long-term non-fertilization and unbalanced fertilization soil was significantly increased, and the risk of crop infection to indigenous diseases was increased. The research results can provide scientific reference for farmland nutrient balance management and soil microenvironment improvement of the agricultural ecosystem in the agro-pastoral ecotone in North China.

Drone imagery protocols to map vegetation are transferable between dryland sites across an elevational gradient

AbstractThe structure and composition of plant communities in drylands are highly variable across scales, from microsites to landscapes. Fine spatial resolution field surveys of dryland plants are essential to unravel the impact of climate change; however, traditional field data collection is challenging considering sampling efforts and costs. Unoccupied aerial systems (UAS) can alleviate this challenge by providing standardized measurements of plant community attributes with high resolution. However, given widespread heterogeneity in plant communities in drylands, and especially across environmental gradients, the transferability of UAS imagery protocols is unclear. Plant functional types (PFTs) are a classification scheme that aggregates the diversity of plant structure and function. We mapped and modeled PFTs and fractional photosynthetic cover using the same UAS imagery protocol across three dryland communities, differentiated by a landscape‐scale gradient of elevation and precipitation. We compared the accuracy of the UAS products between the three dryland sites. PFT classifications and modeled photosynthetic cover had highest accuracies at higher elevations (2241 m) with denser vegetation. The lowest site (1101 m), with more bare ground, had the least agreement with the field data. Notably, shrub cover was well predicted across the gradient of elevation and precipitation (~230–1100 mm/year). UAS surveys captured the heterogeneity of plant cover across sites and presented options to measure leaf‐level composition and structure at landscape levels. Our results demonstrate that some PFTs (i.e., shrubs) can readily be detected across sites using the same UAS imagery protocols, while others (i.e., grasses) may require site‐specific flight protocols for best accuracy. As UAS are increasingly used to monitor dryland vegetation, developing protocols that maximize information and efficiency is a research and management priority.

Contrasting effects of vegetation cover and site condition on biocrust communities in subhumid drylands

AbstractQuestionsBiocrusts perform critical functional roles in drylands, where they are regulated predominantly by differences in climate and soils. We asked whether biocrust cover and composition differ among sites of varying vegetation cover and condition.LocationSubhumid drylands in the Namoi Region, eastern Australia.MethodsWe assessed the effects of different vegetation strata (trees, shrubs, groundcover) and site vegetation condition (index of quality based on vascular plant richness, and the proportion of perennial and native vascular plants) on the cover, richness and composition of biocrust communities at 43 sites in semi‐arid eastern Australia.ResultsWoody plant cover at our sites was negatively related to biocrust cover and richness, but there was only a weak relationship between groundstorey plant cover and biocrusts, suggesting that woody plants are not facilitating biocrusts in this environment. Conversely, greater site condition was strongly associated with richer and more extensive biocrust communities, likely driven by a common response to livestock grazing intensity. There was also a significant multivariate association between biocrust composition and vegetation condition. For example, sites of poorer condition were occupied by generalist taxa, typically short mosses and squamulose lichens, while sites in better condition were characterised by a richer assemblage that included foliose and fruticose lichens, and taller, disturbance‐sensitive mosses.ConclusionsOur study provides empirical evidence of the negative relationship between woody plant cover and biocrusts (amensalism), and the filtering effect of vegetation condition on different biocrust taxa. Predicted drier climates could enhance biocrust dominance by suppressing woody plant growth, while intensified land‐use disturbances are likely to filter biocrust specialists such as fruticose and foliose lichens that are associated with sites in better condition.

Agro-pastoralist Resilience: Emerging Challenges towards Innovated Pathways of Climate Change Effects in Semi-arid areas of Kiteto and Kilindi Districts, Tanzania

Climate change and its variability threaten food security globally, making life uncertain, especially among agro-pastoral communities living in fragile semi-arid areas. This trend has necessitated the exploration of the potential designed and developed pathways and the emerging challenges which reduce the adaptive capacity of agro-pastoralists. This study investigates innovative pathways and challenges facing agro-pastoral communities in adapting to climate change and variability effects on crops and livestock production in semiarid areas of Kiteto and Kilindi Districts. A mixed-method research approach under a correlation case study design was employed. Primary data were collected using a household survey which sampled 362 households, Focus Group Discussion (n=6), In-depth interviews (key informants) and field visits. Descriptive statistics and thematic analysis were used in analysing and presenting the findings. The study results indicate that agro-pastoral communities have observed a decrease in rainfall and an increase in temperature trends that were linked to reduced livestock, cereals and pulses crop production thus affecting the agro- pastoral community’s food security status. The study identified innovative pathways as a response to reduced livestock, cereal and pulse crops production which includes growing drought-tolerant crops, practising intercropping, livestock seasonal mobility, traditional grazing management system through by-laws, pastures rotational uses and traditional water reservoirs (Mboutu). Furthermore, the study identified several challenges to overcoming declining livestock production and crop yields, which include inadequate financial capital (91%), droughts (85.4%), unpredicted weather patterns, (74.7%), emergency of new AJASSS Volume 4, Issue No. 1, 2022 page 20 livestock diseases (50.3%), a lack of reliable weather information (44.2%), low livestock prices(40%), insufficient and delayed delivery of agricultural equipment (37%). All these challenges reduced the resilience capacity of agropastoralists. To ensure the sustainability of fragile dryland communities, this study recommends purposeful institutional intervention plans and increased income diversification as well as more capacity-building activities for increased awareness of climate change adaptation practices in semiarid areas of Tanzania which will increase agro-pastoralists resilience.

Rainy years counteract negative effects of drought on taxonomic, functional and phylogenetic diversity: Resilience in annual plant communities

Abstract Climate models forecast changes in the amount and distribution of rain, which may affect ecosystems worldwide, especially in drylands where water is already the limiting factor for plant life. Annual plant communities are common in drylands where they can complete their entire life cycle during the rainy period while avoiding the dry season. Moreover, seed dormancy allows them to disperse over time by remaining in the seed bank for long periods. However, the extent to which these communities will be able to tolerate increasing drought is uncertain. We performed a 5‐year rainfall reduction treatment under field conditions and determined its effects on annual plant communities in a Mediterranean gypsum ecosystem. We assessed the taxonomic, functional and phylogenetic diversity of these communities each year for 5 years. The taxonomic and functional diversity decreased under the rainfall reduction treatment, whereas the phylogenetic diversity increased. Moreover, the relative importance of species with drought‐resistant functional designs increased in the community assemblages. However, after a rainy season with above average rainfall, all of the diversity values recovered completely even under the rainfall reduction treatment. Our results provide important insights into the responses of these plant communities under a climate change scenario, where they indicate high losses of diversity during drought events but rapid recovery in milder years. Synthesis. Our findings highlight the great resilience of annual plant communities in drylands, which may allow them to tolerate increased drought under the present climate change scenario.

Ecological and Hydrological Indicators of Climate Change Observed by Dryland Communities of Malipati in Chiredzi, Zimbabwe

Existing evidence about climate change in Zimbabwe has tended to focus more on elements and events of the climate system, marginalizing changes in the hydrological and ecological system. To contribute to the improved understanding of climate change, this study captured the observations of climate change in Malipati, a remote agrarian dryland area in the Chiredzi District, Zimbabwe. The aim of the study was to gather detailed insights about perceived environmental changes using the evidence drawn from local and indigenous populations who have close interactions with their natural environment. A household questionnaire-based survey with randomly chosen farmers (n = 116) revealed that participants’ observations of changes in hydrological and ecological system were consistent with available evidence of increasing temperatures and little rainfall recorded in the district. Results also showed high sensitivity of the area to climate change that manifest in various indicators: hydrological changes in rivers, streams, swamps, and ground water; and ecological changes through the behaviour of trees, insects, birds, and wild animals. Sex and age of the participants did not influence the way they perceived most of these changes (p > 0.05). However, education and the period of stay in the area were related to the respondents’ perceived changes in river flows and siltation, and the conditions of swamps (p < 0.05). Our study also revealed deeper insights about the human-biodiversity interactions in the face of climate change in unique areas where communities live alongside wildlife. The evidence drawn from local and indigenous populations can be used to inform local-based solutions to the growing problems of climate change and biodiversity loss. Future studies would need to further examine such areas to understand the mitigation and adaptation practices that would promote the sustainable co-existence of humans and wildlife.

Coordination between water uptake depth and the leaf economic spectrum in a Mediterranean shrubland

Abstract Water is the most limiting resource for plant survival and growth in arid environments, but the diversity of water‐use strategies among coexisting species in dryland communities is not well understood. There is also growing interest in assessing whether a whole‐plant coordination exists between traits related to water‐use and the leaf economic spectrum (LES). We used water stable isotopes (δ2H, δ18O) to quantify water uptake proportions from different soil depths by 24 species in a Mediterranean shrubland. Leaf traits associated with water‐use efficiency, stomatal regulation (δ13C, δ18O) and the LES (SLA, N, P, K concentrations) were also measured. We assessed potential trade‐offs between the above‐mentioned leaf traits, water uptake depth and their relationship with species abundance. We found distinct ecohydrological niche segregation among coexisting species. Bayesian models showed that our shrubland species used a median of 37% of shallow soil water (0–30 cm) and 63% of deep water (30–100 cm). Still, water source proportions varied considerably among species, as shallow soil water‐use ranged from a minimum of 6.4% to a maximum of 68%. Interspecific variability in foliar carbon investment (SLA) and nutrient concentrations was remarkably high, indicating diverse nutrient‐use strategies along the LES. Leaf δ18O, δ13C and δ15N values also differed widely among species, revealing differences in stomatal regulation, water‐use efficiency and nitrogen acquisition mechanisms. After accounting for evolutionary history effects, water uptake depth was coordinated with the LES: species using shallower soil water from fertile topsoil layers exhibited a more acquisitive carbon‐ and nutrient‐use strategy, whereas water uptake from deeper but less fertile soil layers was linked to a more conservative nutrient‐use strategy. Leaf‐level water‐use traits significantly influenced species abundance, as water‐savers with tight stomatal regulation and high water‐use efficiency were dominant. Synthesis. Greater utilisation of water stored in nutrient‐rich topsoil layers favoured a more acquisitive nutrient‐use strategy, whereas a deeper water uptake pattern appeared to constrain access to nutrients. Our findings thus suggest a largely inescapable trade‐off and coordination between soil water uptake depth and carbon‐ and nutrient‐use strategies in low‐fertility drylands.

Farmer extension facilitators as a pathway for climate smart agriculture: evidence from southern Malawi

ABSTRACT Climate smart agriculture (CSA) is increasingly vital for enhancing agricultural adaptation to extreme weather shocks and sequestering carbon in the face of climate change. However, CSA adoption remains low in sub-Saharan Africa (SSA) and other developing regions due to resource constraints and weak agricultural extension systems, among other factors. To reverse this trend and increase CSA adoption, the use of participatory extension services like farmer extension facilitators (FEFs) are increasingly viewed as a pathway to improving extension services in rural communities in SSA and elsewhere. Yet, rigorous analyses of the impacts of the FEF approach as a pathway for CSA adoption remain limited. Here we estimate the impacts of the FEF approach on CSA adoption in terms of resource intensity of CSA practices promoted by FEFs through a large CSA-related intervention in southern Malawi. We apply recursive bivariate probit regression to primary survey data from a sample of 808 households across five districts in the project area across southern Malawi in 2016, accounting for endogeneity and selection bias in farmer interaction with FEFs and the impact of the FEF approach on CSA adoption. Results show that interaction with FEFs had a positive and statistically-significant impact on CSA adoption; low, medium, and high resource intensity CSA categories increased by 42%, 87%, and 96%, respectively. The results suggest that the FEF approach can significantly enhance CSA adoption and thereby contribute to the achievement of the Sustainable Development Goals, including climate action in Malawi, similar contexts in SSA, and elsewhere. Key Policy Insights Participatory extension systems like the FEF approach can improve agricultural extension services in poor communities and thereby enhance CSA adoption in such areas. Smallholder farmer interaction with FEFs can enhance their adoption of resource-intensive CSA practices. Mainstreaming the FEF approach into national adaptation policies and programmes can help scale up CSA adoption in dryland communities. The FEF approach can enhance an achievement of the Sustainable Development Goals, including climate action in dryland developing countries.

Restoring Sahelian landscapes with people and plants: insights from large‐scale interventions

Combining traditional knowledge on native plant species with scientific plant expertise has been established as a critical factor to improve success of restoration interventions, yet evidence on its incorporation across large scales and in Africa, is scant. Even less known are the effective socio‐economic benefits that communities have reaped from restoration activities. This article builds on Sacande and Berrahmouni's paper, further supported by both socio‐economic and biophysical data from large‐scale restoration activities in Senegal, Niger, and Nigeria in support of Africa's Great Green Wall. In total, over 90,000 village households were involved and 56,000 ha of degraded lands planted in 10 countries across the Sahel to initiate restoration in 5 years. Key findings suggest not only ecological benefits, but improvements in livelihoods and health, critical factors underpinning restoration success in the drylands. Results show the profound role native plants and other non‐timber forest products play in the lives and livelihoods of dryland communities. Between 2016 and 2020, 120 tons of seeds were collected from over 110 native plant species and planted in 10 countries, with ecological and economic benefits. Perceived food insecurity significantly decreased in 2020 compared to 2016 observations, declining sharply from 46 to 15% in project sites in Senegal, from 69 to 58% in Niger, and 90 to 25% in Nigeria. In Niger and Senegal, communities generated revenues from fodder species alone of 40 USD/ha per year. The UN decade for Ecosystem restoration 2021–2030 will be an important platform to expand such climate change adaptation and mitigation programs.

Plant–plant interactions determine taxonomic, functional and phylogenetic diversity in severe ecosystems

AbstractAimPlant–plant interactions are an important factor in structuring plant biodiversity. However, most studies on the impacts of plant–plant interactions on biodiversity focus on species richness and to a lesser extent on other facets of diversity. When other facets of biodiversity are considered, studies often include a limited set of environmental conditions. We aimed to quantify the impacts of nurse plants on taxonomic, functional and phylogenetic facets of plant biodiversity and how these impacts change across environmental gradients.LocationWe report data on 28 alpine and 50 dryland sites, established in 11 countries.Time period1998–2019.Major taxa studiedVascular plants.MethodsWe analysed plant–plant interactions using co‐occurrence analyses and obtained information on the functional traits and phylogenetic relationships of the beneficiary species. We calculated the change in taxonomic, functional and phylogenetic diversity caused by the presence of nurse plants and environmental conditions.ResultsNurse plants enhanced taxonomic and phylogenetic diversity in alpine communities and enhanced functional and phylogenetic diversity in dryland communities. However, they had a positive effect on functional and taxonomic diversity only in moderate environments in alpine and dryland communities, respectively. The effects of nurse plants were larger in drylands for functional and phylogenetic diversity and in alpine communities for taxonomic diversity. Interestingly, nurse plants induced nonlinear changes in all facets of biodiversity across environmental gradients, whereas biodiversity tended to increase linearly toward more benign conditions in open interspaces.Main conclusionsFacilitation is important in alpine environments to maximize taxonomic diversity and has a more consistent positive effect on the functional and phylogenetic diversity of drylands. In general, effects of facilitation on biodiversity peak in moderate environmental conditions, which suggests that nurse plants can protect biodiversity from impacts of climate change mostly in those places currently under low environmental stress and that will be likely to experience moderate stress levels in the future.

Functional heterogeneity of habitats and dry season forage variability in an Okavango Delta landscape, northern Botswana

The late dry season is a period when forage resources become limited in some African savannas that can induce a strong demographic bottleneck in herbivore populations with limited access to resource heterogeneity. This study determined forage quality and quantity between wetlands and drylands habitats during the late dry season. We subjectively sampled forage characteristics in four habitat types around the distal reaches of the Tsum Tsum floodplains of the Okavango Delta during the late dry season of 2015. The habitat types were mopane and sandveld woodland far from floodplains (two major dryland habitat types), sandveld habitats that receive soil moisture inputs from adjacent floodplains (wet sandveld) and sedgeland habitat within the floodplain. Leaves collected from forage in each habitat type were oven dried, milled and analysed for total nitrogen. Data of greenness, height, biomass and protein were analysed using Kruskal-Wallis test. Forage in wet sandveld had by far the highest protein content (~16%) of all habitat types but forage height and biomass were very low, whereas sedgelands had the highest biomass of adequate-quality forage, while dryland communities had the lowest quantity and quality of forage. Thus, foraging between a higher-biomass, adequate-quality reserve resource (sedgeland) and a high-quality but low-quantity bridging resource (wet sandveld) can help to ensure a balanced protein and fibre intake during the late dry season. Our study demonstrated the importance of wetland habitats for providing green forage with sufficient biomass and protein to sustain herbivores over the late dry season.

Spatiotemporal changes of snow metrics in mountainous data-scarce areas using reanalyses

Mountain snowmelt is a critical water resource for achieving food and water security in drylands. Climate change impacts the snowmelt and consequently water resources reliability in downstream communities in drylands. Data limitation is one of the main challenges for assessing such impacts. This study assessed the trend in snow depth (SD), snowy day to wet day (SDWD), and snow phenology-related metrics in data-scarce snowy areas of Iran over 1987–2017. Furthermore, the contribution of temperature warming, precipitation and Arctic Oscillation (AO) anomalies to the snow metrics trends was investigated. The analyses were performed using the more accurate reanalyses selected between ERA-Interim and ERA5. The trend magnitude and significance were also assessed during the December-January-February (DJF), March-April (MA), and December-January-February-March-April (DJFMA) using the Sen’s estimator and Mann-Kendall (MK) test, respectively. Given the ERA5′s superiority, this product was employed for the trend and contribution analyses. The SD, SDWD and snow cover duration (Sdur) had a decreasing trend at more than 90% of study area. Except for snow cover onset date (Ds), MK detected a significant trend in the snow metrics at 40% or more of the studied regions. The more humid regions experienced a greater SD reduction. The SDWDDJF also decreased by less than 1% for the areas having average winter wintertime temperature below the threshold of −2.80 °C. The downward trend in Sdur was largely due to the earlier snowmelt rather than later Ds. A decline of 5 > day per decade was found for Sdur at the areas with DJFMA temperature below the melting point. The SD, SDWD and phenology metrics changes can be accounted for by temperature warming in most regions. The SDWD-AO relationship was statistically significant for the majority of the cases. The AO anomalies seem to impact SDWD via affecting wintertime temperature. The decrease of snow metrics indicates the occurrence of more severe and frequent dry snow droughts in the studied sub-basins. Thus, drought adaptation strategies need to consider the patterns of snow metrics in addition to total precipitation under global warming. The ERA5 outputs can be applied for evaluating snow drought under data scarcity.

Assessing the Impact of Land Cover, Soil, and Climate on the Storage Potential of Dryland Sand Dams

Sand dams, a water-harvesting structure employed by rural communities in drylands have an inconsistent record of effectiveness. While many sand dams are highly functioning, improper siting, siltation, seepage, and high rates of evaporation from shallow sand reservoirs inhibit the water storage capacity of some sand dams. This study examines large-scale drivers of sand dam storage potential through analysis of an integrated surface and subsurface flow model. Multiple simulations were run, and comparative simulation analyses consider the effect of geomorphological factors, intraseasonal rainfall variability, and future climate conditions on sand dam performance criteria. The analyses revealed that a watershed highly cultivated with low water crops actually reduces evapotranspiration below that of natural vegetation and supports higher groundwater recharge. Additionally, intraseasonal variation and volume of rainfall impact sand dam performance less than the prevailing pattern and duration of dry and rainy seasons. Sand dams constructed in watersheds with sandier soils may experience greater connectivity with the stream margins and thus provide additional groundwater recharge. Lastly, climate change may improve some conditions desirable for sand dam performance, such as extending the duration of the rainy season and reducing overall evapotranspiration. However, the interactions between the expected climate change conditions and other geomorphological factors may result in a net decline in sand dam performance. The results of this study may help identify watersheds that are likely to support a sand dam with high potential for capturing and storing water throughout the dry season.