Journal of Arid Environments最新文献

Banqueting is a simple and cheap soil conservation practice in natural rangelands under dry climates. Little research exists about its impacts compared to other land uses, where agriculture and land abandonment may be important reasons for degradation. This study has evaluated water infiltration and key physico-chemical properties of soil in natural rangelands with banquets in West Azerbaijan (North-Western Iran) compared to: (i) undisturbed sites (assumed as reference condition) and (ii) cultivated or abandoned dry farmlands. Under these soil conditions, the texture, bulk density, porosity, water content, pH, electrical conductivity, organic carbon and carbonate contents of soil (using common physical-chemical methods) as well as the hydraulic conductivity (using a single-cylinder infiltrometer) were measured in the topsoil (0–20 cm). This data was further processed by applying the Principal Component Analysis and the Agglomerative Hierarchical Cluster Analysis. In areas with banquets, soil hydraulic conductivity was higher by 84% compared to dry farmlands (abandoned or not), where water infiltration was noticeably reduced (−44%) compared to the reference soil condition. Moreover, a noticeable increase in organic carbon content (+80%) and a lower salinity (−36%) of soil compared to cultivated areas was measured. These effects are important to enhance soil fertility on one side, and resistance to erosion on the other side. Therefore, in the experimental areas, banqueting may counteract the degradation of soil due to the agricultural activity as well as its abandonment, and restore the properties of the undisturbed soils that are typical of natural rangelands. The results of this study may be of help for landscape managers and agronomists for the pressing needs for soil conservation and productivity in semi-arid areas that are prone to degradation and abandonment.

Ongoing climate change and anthropogenic impacts will continue to worsen the problem of water crisis. In order to explore practical solutions for drought and climate change adaptation, this work uses a set of different methodologies to evaluate an operational fog collection project and discuss solutions for some emerging challenges. This study uses fog collection rate, Water Quality Index (WQI) and interviews with the community as indicators for the assessment. Results indicate that the project continues to deliver improved drinking water access to the community. Fog harvesting rate yielded an annual average from 1.6 to 6 L/m²/d. Interviews confirm the social commitment of the local community. However, challenging points emerge: (1) ongoing groundwater pollution due to the lack of sanitation; (2) if fog water is the only source, inconsistent fog yields may negatively impact water availability; (3) poor solid waste management. The findings represent a baseline for assessing and benchmarking other similar projects or project proposals in the Atlantic coast of North Africa. Therefore, the proposed methodology can also be used in other fog collection projects around the world.

Where they occur at high densities, herbivores are likely to impact ecosystems by functioning as nutrient vectors that shift nutrients from areas where they graze to other locations. Such lateral shifts in nutrients are important to understand as they can alter the balance of species interactions and composition of ecological communities. In arid Australia, kangaroo (Macropus spp.) populations have irrupted due to suppression of their chief predator and their presence can have marked impacts on vegetation and soils in areas where they graze. Kangaroos are hypothesised to facilitate the transport of nutrients by ingesting organic material and depositing it in the form of faecal matter and urine under the shade of trees where they rest during the day. Here, we investigate the role that kangaroos and shade play as nutrient vectors and nutrient sinks, respectively. We compared kangaroo visitation and soil nutrients under experimental shades with unshaded areas in an arid landscape with little natural shade. Kangaroo visitation was greatest at shaded plots. Dung accumulation was greater at shaded plots than unshaded plots. Total carbon (TC) was greater in soils within shaded plots than control plots; however, there was no difference in TC between shaded plots and procedural control plots. There was no difference in total nitrogen and plant available phosphorus between shaded, control and procedural control plots. Our findings demonstrate that the presence of shade in an arid landscape influences the microhabitat choice of kangaroos, but only partially supports the hypothesis that nutrients concentrate within the soil under shade.

The microbial communities in saline lakes play important roles in maintaining their unique ecosystems. However, little is known about the vertical distribution of the sediment microbial communities in saline lakes. We therefore studied the vertical distribution of the sediment microbial communities and their relationships with environmental factors in Ebinur Lake, China. Our sediment cores, collected in 2018, were analyzed using Illumina MiSeq sequencing. The results indicated that microbial diversity significantly increased in the sediment core with increasing salinity. At the phylum level, the six most abundant microbes were Proteobacteria, Chloroflexi, Bacteroidetes, Firmicutes, Gemmatimonadetes and Deinococcus-Thermus, accounting for 42.9%, 10.7%, 9.6%, 5.2%, 4.6% and 3.6% of the total reads, respectively; At the genus level, the six most abundant genera were Halothiobacillus, Desulfotignum, Truepera, Salipaludibacillus, Marinobacter and Halomonas, accounting for 15.4%, 4.8%, 3.6%, 2.7%, 2.6% and 2.3% of the total reads respectively. There were significant vertical variations in microbial community composition (MCC) between upper layers and lower layers. Canonical correspondence analysis demonstrated that salinity was the dominant environmental factor affecting the vertical variation of sediment MCC. Thus, this study could greatly improve our understanding of the MCC of saline lakes in the arid and semi-arid ecosystems.

Serious concerns have arisen regarding the depletion of groundwater aquifers and water shortage, particularly in the Middle East. The utilization of qanat, subterranean tunnel-wells, may serve as a solution to addressing water scarcity and present targeted strategies toward sustainable groundwater management. This research presents an analysis of the spatial distribution of active qanats in Afghanistan, Iran, Iraq, and Syria, considering the annual rainfall rate, the elevation from sea level, water stress risks, and groundwater table decline. It aims to identify the qanat sites that may be maintained and utilized. The findings reveal distinct geographical clusters of qanats, with a concentration in mountainous regions characterized by consistently high elevations ranging from 1500 to 2500 m above sea level and annual rainfall rates between 200 and 300 mm. In contrast, a more sporadic presence is observed in low-lying plains with elevations ranging from sea level to 1000 m, where the annual rainfall ranges between 300 and 600 mm. Participation in the restoration, maintenance, and utilization of qanats in regions facing high water stress and the risk of groundwater table decline, such as the central plateau of Iran, may offer a sustainable solution to water risk challenges.

Local ecological knowledge (LEK) of forage resources available in the forest is crucial in the sustainability of extensive grazing systems in the arid Chaco region. Here, we document goat farming management strategies of local peasants, assess their LEK about forage plants and evaluate the local perception related to pollination of native tree species. We used semi-structured interviews to obtain ethnoecological information and a cognitive approach to inquire about the plant species considered as fodder and their relative importance. Peasants listed a total of 48 ethnospecies (60 species from 23 botanical families) used as fodder. The most important forage plants in our study were Neltuma spp., Sarcomphalus mistol and Castela coccinea, which provide high quality fruits and also leaves as forage at different moments of the year. Local producers did not identify pollination as a key factor for the production of forage fruits, but they did emphasize the importance of climatic factors for fruit production. This ethnoecological information related to forage plants and factors that determine fruit production is important to understand peasant management systems that sustain local communities and play an important role in forest persistence.

Dust storms, resulting from aeolian erosion, pose significant environmental hazards, while farmland is one of the main sources of dust storm release. An effective strategy to mitigate surface wind speed and curb dust emissions involves the establishment of windbreaks on the periphery of oasis farmland. This study conducts a series of numerical simulations using computational fluid dynamics (CFD) to explore the airflow fields around windbreaks with diverse systematic structural parameters, encompassing porosity, planting spacing, and fence effects. The main findings are as follows: (1) When the vegetation porosity is consistent (e.g., porosity α = 0.7, 0.8, and 0.9), exact geometry results can effectively reflect the distribution of wall shear stress, while the porous medium model overlooks these details. (2) The “Venturi effect” contributes to the acceleration of surface erosion and improper planting spacing results in an elevation of near-surface velocity. Planting spacing of 0.5 m demonstrates superior wind speed reduction performance, mitigating aeolian erosion and accumulation. (3) When the fence is positioned at l = 5h (h represents the height of the windbreaks), the flow field around the windbreaks is minimally influenced. The optimal placement distance for fences should be close to the windbreaks, featuring minimal porosity (l = 0 h, α = 0.1), extending the shelter distance from 3 to 4 h to 5–6 h. The research results can provide a theoretical basis for optimizing the plant configuration of biological desertification control and soil erosion control measures.

The caatinga, a thorny deciduous shrub-arboreal vegetation predominant in the semiarid Northeast Brazil region, has faced chronic anthropogenic disturbance since the arrival of Europeans. Areas experiencing strong anthropogenic pressure and climatic vulnerability are often overlooked in floristic and phytosociological studies, leading to limited knowledge about their biological potential. Thus, our objective was to assess the current vegetation state in three severely degraded nuclei undergoing desertification in Ceará and determine, based on the analysis of plant diversity (richness) and structure, if there is potential for natural regeneration. We sampled 36 plots (3.24 ha), measuring trees and shrubs with a diameter at ground level (DGL) ≥ 3 cm. The vegetation was stratified into three degradation levels: open, intermediate, and closed. The open level, most impacted by human activities, exhibited reduced plant richness, density, biomass, and height compared to other levels. In contrast, the intermediate and closed covers, prevalent in the study area, showed no significant differences from each other or from caatinga areas outside the desertification nuclei. We concluded that even severely degraded areas should possess high biological potential due to the presence of preserved remnants serving as reservoirs to maintain diversity and vegetation structure in the region.

Plants in seasonally dry forests, such as the Caatinga in Brazil, possess adaptive characteristics to endure prolonged periods of drought and intense sunlight. However, few studies have delved into understanding, as proposed here, the convergence of these traits based on morphoanatomical features. Therefore, based on a systematic review, we investigated the morphoanatomical traits of Caatinga plant's leaves in terms of their occurrence and frequency among species, as well as their combinations. This review encompasses data from 69 species distributed across 24 botanical families, with 13 species exclusive to the Caatinga. Through this review, we present the most common morphoanatomical leaf traits of Caatinga plants, discussing their functional significance in dry forests. Traits such as uniseriate epidermis, tector trichomes, amphistomatia, dorsiventral mesophyll and crystals were the most prevalent. Additionally, traits not typically described as advantageous for semi-arid regions, such as stomata at the same level and/or above common epidermal cells, were identified. Our review unveils the significant sharing of morphoanatomical leaf characteristics among Caatinga plants, with the observation of three clusters associated with these traits, composed of subshrub, shrub, arboreal and/or herbaceous species. The shared traits underscore the evolutionary association between traits and the environment. Finally, this comprehensive overview of these traits allows us to understand the dynamics of Caatinga plants and serves as a foundation for future analyses of the varying vulnerability of plants within each cluster to climate change.

Birds that build open-cup nests in semi-arid or arid habitats have difficulty in maintaining clutch temperatures during incubation in a suitable incubation range due to high air temperatures and solar radiation, resulting in either embryo death or behavioural responses to preserve clutch viability. We investigated how Southern Fiscals (Lanius collaris), open-cup nesting passerines with female-only incubation in the Kalahari basin, allocated time for self-care (off-bouts) and incubation (on-bouts) and whether egg shading, a previously described behaviour in this species, is a widespread response during hot periods. We used a dual approach combining temperature dataloggers in the nest and behavioural observations during the hottest hours of the day. We found that in the early morning and late evening, Southern Fiscals behaved similarly to species incubating in temperate habitats by alternating off- and on-bouts, but during the hottest hours of the day, shading became the main activity. Behavioural observations were key to describing this behaviour indicating that it is necessary to combine different data collection strategies to successfully assess the behaviour of open-cup nesters in hot environments.