Journal of Arid Environments最新文献

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.

Even though steadily increasing, biofluorescence is a rarely documented phenomenon in vertebrates. Within geckos, only six species have been shown to produce fluorescence and only one case of dermal fluorescence has been reported. Here, we report on the discovery of dermal fluorescence in the Dune Sand Gecko (Stenodactylus doriae), the Eastern Sand Gecko (S. leptocosymbotes), and the Arabian Web-footed Sand Gecko (Trigonodactylus arabicus), three closely-related, nocturnal, desert-adapted Arabian geckos. We show that there are interspecific differences in fluorescent regions which might be linked to the habitat preference and behaviour of each species. Our results are in agreement with prior hypotheses suggesting that desert-adapted geckos might use dermal biofluorescence for conspecific signalling. With the present work, we expand the current knowledge on skin fluorescence in reptiles and provide new insights on fluorescence of desert-adapted geckos.

The Caatinga biome, characterized by its dynamic vegetation due to climate and land use changes, experiences varied environmental responses during the dry and rainy seasons. This research aims to dissect the complexity of surface radiation fluxes, vapor pressure, and air and soil temperatures across three distinct vegetation densities within the Caatinga: recovering, degraded, and preserved. Utilizing data from Moderate Resolution Imaging Spectroradiometer/Enhanced Vegetation Index products to analyze these densities offers a novel lens through which to view the biome's reaction to climatic shifts. Our findings unveiled specific patterns of solar and longwave radiation fluxes that correlate with key climatic variables like air temperature and surface albedo. This investigation not only addresses a critical gap in our knowledge of a globally significant but underexplored biome, but it also advances our comprehension of how vegetation density influences radiation fluxes in arid settings. Insights from this study are vital for forecasting and mitigating the ecological and climatic impacts of land cover transformations in semiarid regions worldwide. Significantly, the degraded site displayed nearly double the solar radiation reflection (138 Wm⁻²) compared to the recovering site (68 Wm⁻²), underscoring the role of vegetation density in modulating local climate conditions, despite atmospheric consistency across the study sites.

Drought, a complex natural hazard, poses significant challenges for scholars in drought risk management due to the perceived lack of suitable assessment, prediction, and monitoring tools. Addressing these challenges requires sophisticated tools capable of precise and timely assessments. This study leverages the rapid advancements in machine learning (ML) and remote sensing (RS) to develop models for anticipating and estimating drought risk, particularly focusing on identifying affected and sensitive locations in Ethiopia's Borena Zone. The research involves a two-phase investigation, examining historical drought patterns and forecasting scenarios for 2028. The GridSearch algorithm is employed for optimal hyperparameter tuning in ML, highlighting the CatBoost algorithm as the most accurate predictor for the Standardized Precipitation Index (SPI). With impressive performance metrics, including Mean Squared Error (MSE) of 0.017, Mean Absolute Error (MAE) of 0.102, Root Mean Square Error (RMSE) of 0.129, and an R-squared (R²) value of 0.84, this study excels in providing precise spatiotemporal accuracy for drought prediction. The findings underscore the importance of time-series drought prediction, offering crucial insights for decision-makers and planners to address and mitigate drought impacts at various scales. This study contributes valuable information by emphasizing the significance of understanding drought occurrence's temporal and spatial dimensions.

The severe 2014–2020 drought in the southern Kalahari of South Africa resulted in extensive herbaceous cover and standing biomass losses. Droughts are a common phenomenon in this semi-arid savanna. The plants of this region have adapted to survive extreme rainfall variability and drought events. This adaptability and the inherent resilience (i.e. the ability to recover to its original state) of vegetation in the southern Kalahari enables it to recover quickly when conditions become more favourable. Droughts in the region are, however, predicted to increase in frequency and intensity due to global climate change. The associated increased aridity may also push many species beyond their tolerance threshold, leading to permanent shifts in vegetation dynamics. The aim of this study was to determine: (i) the growth vigour, cover abundance and productivity of herbaceous plant functional groups during the drought, (ii) the rate of post-drought recovery and (iii) the relative resilience and resistance of herbaceous plant functional groups. The drought affected all herbaceous plant functional groups as growth vigour, cover abundance and productivity were extremely low during the drought. All herbaceous growth started to recover post-drought but differed in their rate of response. Annual herbaceous species were found the be remarkably resilient to drought while perennial grasses were less resilient but far more resistant to the drought. Despite the resilience and rapid recovery of herbaceous growth, compositional changes post-drought were limited due to the degraded condition of the rangeland prior to the drought. The results emphasised the importance of sound management practices in the face of climate change.

Understanding resource use of invasive species provides insights for predicting and mitigating their impacts on biodiversity. We explored the predictability of diet of the invasive common warthog by describing and comparing the diet of warthog populations from two semi-arid, invaded sites, Addo Elephant National Park (AMC), and Great Fish River Nature Reserve (GFRNR), Eastern Cape, South Africa. These sites are both dominated by the Subtropical Thicket biome, but differ in vegetation type. We used forage availability to estimate diet preferences at AMC. We predicted that warthog would consume grass in invaded landscapes. Additionally, we predicted that the diet at one invaded site would predict this at another invaded site. As predicted, warthog mainly consumed grass at both sites (AMC – 87.4%, GFRNR – 88.5%), eating few woody plants, succulents, and forbs. Cynodon dactylon was the most consumed species in AMC, in GFRNR this was Eragrostis curvula and Cymbopogon pospichilii. Our ability to predict the diet between sites was constrained by variation in the plant species consumed. We found strong relationships between the consumption of preferred plant species at AMC and their consumption at GFRNR. We show that warthogs are specialised grazers outside their native range and thus can be expected to impact grass communities in invaded areas, especially preferred grass species. Thus, conservation managers need to monitor grasses in areas invaded by warthog to better detect and manage their impacts.