Journal of Arid Environments最新文献

Nutrient dynamics directly influence forest productivity, yet their exploration in tropical dry forests, particularly in human-modified landscapes, is limited. We examine aboveground and soil carbon, nitrogen, and phosphorus concentrations and stocks in 19 stands across gradients of rainfall, chronic anthropogenic disturbances (CAD), aboveground biomass (AGB), and soil fertility in a Caatinga dry forest. Leaves exhibit three times higher N and P concentrations than twigs but a 20% lower C concentration. Conversely, the soil compartment presented the lowest concentration scores across all nutrients. Stoichiometric N ratios exceed 20 in all compartments. Soil C, N, and P stocks are approximately two, seventeen, and twelve times greater than aboveground biomass. Rainfall, CAD, and AGB exert both positive and negative effects on C and N concentrations and stoichiometric ratios in twigs and soil. Our results suggest that the Caatinga dry forest in human-modified landscapes supports woody plant assemblages with high nutrient concentration but reduced stocks across all compartments. Both environmental and human-related disturbances play specific roles by affecting nutrient availability. In this P-limited system, reduced nutrient stocks and the prevalence of disturbance-adapted plant species apparently dependent on biotic associations for nutrient uptake render Caatinga forest productivity and resilience highly susceptible to human disturbances.

Comparative studies of basic physiological performance are needed to give insight of how grass species survive and grow under current and more severe drought predicted in the framework of climate change in arid steppe grasslands. In this study, photosynthetic performance and stomatal conductance (gs) were measured in leaves of six main grass species of southern Patagonian steppe, after exposing plants to different conditions of water availability. There was a negative linear relationship between photosynthesis at light saturation (Pmax) and plant water stress, expressed as pre-dawn leaf water potential (ψ_pd), mainly explained by the reduction in gs. A negative linear relationship was also observed between the photosynthetic efficiency (α) and the ψ_pd of plants, but only under moderate to severe water stress conditions. Grass species had different response to water stress graded in the following order: Pappostipa chrysophylla > Festuca gracillima > Rytidosperma virescens > Poa dusenii > Bromus setifolius. These results can assist to understand the natural spatial distribution of these species under arid conditions, to predict their performance under changing climate, and to select proper species for restoration plans in steppe grasslands.

Cultivated for millennia, the grapevine held a special status as one of the most important fruits in the historical Levant and the Mediterranean world. However, since past farmers typically did not leave written accounts of their activities, viticulture history is often shrouded in ambiguity, especially concerning the classification of grapevine landrace varieties. Hence, the study of archaic viticulture relies heavily on methodological fusion to unravel its more readily discernible biological and oral traditions. We therefore merged archaeological fieldwork, historical archival analysis, field geography and ethnographic interviews to collect multifarious data on the Dabouki grapevine. Our analytical synthesis enabled us to depict how, over the course of history, diverse communities variously grew this cultivar in dryland vineyards. The cultural history of the Dabouki stretches from at least the Ottoman era, when it was widely planted throughout the region under various names, to its current revival by enterprising Israeli and Palestinian winemakers. The majority of our research was conducted within a unique environmental corridor in the western Negev of Israel where dense concentrations of relic Dabouki grapevine survive. Our paper surveys the cultural history of the Dabouki grape as a flagship cultivar in the intergenerational horticultural regimes of arid land farmers in the western Negev of the southern Levant. Remarkably, archaic Negev viticulturalists used the same cultivars across successive historical periods and varying socioeconomic contexts. As such, the paper illustrates that arid regions with longstanding winegrowing traditions are ideal for locating endemic grapevines that apparently can withstand challenging growing conditions. Focusing on the enduring legacy of the Dabouki, we suggest how historical knowledge of ancient dryland farming systems and landrace cultivars can bolster the sustainability of contemporary viticulture.

Gypsum soils, despite physico-chemical constraints, harbor a unique biota composed of specialist (gypsophiles) and stress-tolerant non-specialist species (gypsovags). Gypsophily has been addressed in plants, although is important to ask whether lichen communities also contain gypsophile species. Therefore, our main aim is the analysis of the affinity of lichens for the gypsum substrate in Spain. Affinity was estimated using two methods: a “geological method”, overlapping lichen occurrence data on a geological map of Spain; and a “biological method”, overlapping the occurrences on a map constructed with the distribution of plant gypsophiles. To assess the accuracy of both methods, we compared them with a literature review. Lichen occurrence data was obtained from GBIF. The biological method was the most accurate as it showed similar percentages to the literature review. The affinity for gypsum substrate has been effectively demonstrated by the employment of these methods, probing the existence of a group of lichens considered gypsophiles. Twenty lichen species are considered gypsophiles, 7 strict and 13 preferential (ca. 40% of 50 taxa analyzed), and 30 gypsovags. This approximation can apply to the study of the affinity for the substrate for other organisms/substrates, and for characterizing geological units when detailed geological maps are not available.

Surveys in arid regions worldwide reveal the widespread presence of naturally found Terrestrial Snails (TSs) in extreme arid and semi-arid regions and poor soil conditions such as eroded loess plains. A significant beneficial connection between TS and their impact on ecosystem functioning is suggested including their use as bio-fertilizers. The study was conducted from 2017 to 2023 in Northern Negev, Israel, at the PWA farm and Sayeret-Shaked LTER. The study aimed to determine the influence of TSs on soil fertility and explore its potential contribution to sustainable and profitable agriculture. The findings indicate that the local TSs contributed to a 2% increase in organic matter content, a significant 60% increase in Calcite-Magnetite, and up to six times higher levels of soluble Calcium and Magnesium compared to unaffected soil. An increase with a potential for CO₂ inorganic sequestration. It is also indicated that successful agricultural utilization of TS relies on unmanaged rocky slopes for reproduction, designated migration paths for farmland access, and a unique cultivation approach to enhance decomposition. The finding may enable policymakers, and regional or government agencies to further invest in local ecosystems, and effective management tools for enhancing the reproduction of bio-fertilizers such as TS are also raised.

This study focuses on the traditional methods used by the Janabib Bedouin tribe in the Negev Highlands to cultivate wheat and barley during the British Mandate period from 1917 to 1948. Despite the fact that this region receives only 90 mm of precipitation per year on average, and was located at a great distance from settlements and markets, the local Bedouin cultivated cereals by exploiting the ancient agricultural terraces from the Byzantine period which prevented runoff and distributed water over the agricultural plots. This research also found that the choice of which cereals to grow in different years, were determined by local climatic conditions. Thus, the Bedouin who lived in the Negev Highlands before 1948, developed specific adaptations in order to survive in these arid conditions.

The targeted removal of a non-native species can result in secondary invasions and other unexpected shifts in plant community composition, but the persistence of these effects is less well known. We investigated how the plant community changed at three time points including before removal (pre-removal), in the years directly following removal (post-removal), and 16 years following Tamarix removal (recent) in an arid depressional wetland. Non-native species cover increased and several non-native species invaded the study area in the years between post-removal surveys and the recent time period, suggesting Tamarix removal may have been a catalyst for increases in non-native species abundance. We also found an increase in the cover of species tolerating upland conditions, and these species were largely non-native. Overall, interactions between targeted removal and shifts in the abiotic environment due to climate change are important drivers of persistent shifts in the plant community. Hydrogeomorphic restoration is likely needed in tandem with invasive removal to see improvements in riparian health, particularly when the invasive species to be removed is a passenger in addition to being a driver of change.

Animal populations that require tree cavities can be either limited or structured depending on the quality and availability of tree cavities in their ecosystems. Over the last century, the Caldén forest of Argentina has experienced severe habitat degradation due to anthropogenic activities. Here, we report the density and characteristics of cavities and their vertebrate users in areas of the Caldén forest with two different types of management: a protected area and an area with cattle ranching. The average density of cavities was 16.1 cavities/ha. However, the reserve's cavity density was four times higher than the ranch's (19.5 vs. 5.8 cavities/ha). The characteristics of the cavities and their support trees showed significant variations, but they were generally similar between sites. Forty-four vertebrate species use or may use tree cavities. The proportion of recorded species using cavities in the reserve was higher (30/41 vs. 6/32; p < 0.01). While most cavity users in the semi-arid forest are not threatened, this ecosystem has been dramatically fragmented, with only 11% of its original area remaining. If anthropogenic activities continue to alter this fragile ecosystem, it is possible that in the future, many species, including tree cavity nesters, will suffer a decline in their populations.

The impacts of anthropogenic activities have significantly contributed to recent and future climate changes worldwide. The future effects of climate change on biodiversity have been intensively studied globally over the past two decades. Currently, dry ecoregions are among the most threatened ecosystems in the world. In South America, three such seasonal dry ecoregions stand out: the Cerrado, Caatinga, and the Gran Chaco. Among these, the Chaco has experienced high deforestation rates and landscape degradation over the last decade, making it a top priority for conservation efforts. In this study, we employed ecological niche modeling to estimate the present and future distribution of snakes in the Chaco region. Our goal was to assess how snake diversity will change with projected climate changes across this geographic area. Our findings suggest that snake assemblages in the Chaco will undergo significant changes under future climatic conditions, with a clear trend toward biotic homogenization of the ecoregion and a decrease in species richness. These negative changes will likely extend to the protected areas within the Chaco, resulting in biotic homogenization and a loss of species richness.