Journal of Arid Environments最新文献

The co-occurrence of mistletoes and Lantana camara (hereafter, lantana) is common in southern Africa, yet little is known about how they interact. To fill this gap, we investigated whether mistletoe-infected trees facilitate lantana invasion in a semi-arid southern African savanna. We compared invasibility, native woody plant diversity and soil parameters beneath mistletoe-infected and non-infected trees. We trapped bird droppings beneath mistletoe-infected and non-infected trees and conducted germination experiments to check if they contained viable lantana seeds. Regardless of whether trees were legumes or non-legumes, the subcanopy environments of mistletoe-infected trees had significantly higher invasibility than non-infected trees. The probability of lantana invasion beneath trees increased with mistletoe-infection levels. Soil nutrient concentrations were higher beneath mistletoe-infected trees than non-infected trees. Subcanopy invasibility was positively correlated with soil nutrient concentrations and negatively with native woody plant diversity. We found viable lantana seeds in bird droppings beneath mistletoe-infected trees. Put together, our findings indicate that mistletoes indirectly facilitate lantana invasion by enriching soil nutrients and attracting lantana seed dispersers. Our work provides a rationale for the necessity to simultaneously manage mistletoes and lantana where they co-occur to reduce invasion of the latter.

Cacti are threatened mainly by loss of habitat and illegal commerce. Because of this, it is essential to know their demographic characteristics. We systematically reviewed the publications with matrix population models (MPM) and integral projection models (IPM) in indexed journals, databases like the COMPADRE Plant Matrix Database and grey literature. In each publication, we recorded the literature characteristics, the population attributes, and the methods and metrics applied to describe them. We reviewed studies published until April 2022. We found 83 publications applied demographic modeling, 43 of which were of grey literature. Most studies were conducted in North America and on the tribe Cacteae, with a scarce representation of South American cactus. Compared to a previous review from 20 years ago, our study recorded a 488% increase in the number of publications and a 33.3% increase in the COMPADRE demographic database. We found demographic data for 65 taxa and very few studies covered a medium-to long-term period. MPMs were the most used until the 2009 when IPMs began to gain popularity. Population growth rates were commonly close to the unit (λ ≈ 1), but we identified a wide range of λ values. Species position in the demographic triangle showed that the populations in the tribes Echinocereae, Cereeae and Cylindropuntieae were located towards the end of the survival axis, while those in the tribes Cacteae, and Opuntieae had a more variable location. Applications of demographic models have focused on the analysis of life history traits (growth and turnover) and employing numerical simulations to simulate the consequences of variations in vital rates on λ. Interactions with the climate and the nurse-protected system are analyzed frequently. Nonetheless, a limited number of research explores the socioeconomic and political components of management and conservation. Finally, even though Cactaceae is the plant group with the most extensive demographic research, models are available for only 3.5% of the species.

Knowledge pertaining avian reproductive phenology and life history is important to understand population dynamics under current climate change. Understanding about changes that occur in these dynamics and factors influencing nesting success in modified habitats is also necessary. We studied reproductive phenology and nest characteristics of birds that nest in an agricultural area within an arid region of central Mexico, and evaluated changes in survival and nesting initiation throughout three years having variation in weather patterns. We registered more nests and greater avian reproductive success in years having the highest rainfall. Within years, nest survival increased as nest age advanced and with increasing nest height in some species. We observed lower incidence of nest parasitism in the agroecosystem in relation to those reported for less modified habitats in semiarid environments. We also observed cases of ectoparasitism by dipteran larvae in chicks of two bird species.

We evaluated the emergence of three shrub native species from the Monte Desert, the most arid ecoregion of Argentina, in substrates artificially constructed (technosols) with different texture and salinity under nursery garden conditions. Two of the studied species (Strombocarpa strombulifera and Neltuma alpataco) had high emergence percentages (96.00 ± 4.62% and 98.00 ± 2.31) regardless of differences in texture and salinity. On the other hand, Larrea divaricata showed high emergence (72.00 ± 6.68%) in non-saline sandy loam soil with gravel, and minimum values in saline and fine-textured substrate (18.33 ± 6.22%). We conclude that studying seedling emergence performance in substrates under nursery garden conditions constitutes a preliminary step for the pre-selection of species for seed-based restoration in arid lands. We also found that technosols can serve as amendments, promoting the emergence of seedlings from various species depending on their formulation.

We present the first empirical information on floral traits, floral visitors, and breeding system of Anarthrophyllum strigulipetalum, a rare and charismatic plant species that inhabits rocky terrains in the harsh semi-arid landscapes of northwestern Patagonia. Despite being large plants (∼1.7 m² surface area), with a showy floral display (>100,000 flowers/plant), protracted flowering period (∼1 month), high nectar production (16.7 μl per flower), high pollen viability (96%) and pollen receipt (∼200 grains/stigma), species reproductive success was very low, with less than 1% of the flowers developing into fruit. Only birds triggered the flower-opening mechanism and carried pollen, whereas insects behaved as nectar thieves. The addition of nectar seemed to increase fruit formation compared to control flowers, whereas nectar removal tended to decrease fruit set. The natural low fruiting levels could be the result of a combination of factors such as low legitimate pollinator visitation rate, low-diverse and poor-quality pollen receipt due to geitonogamy promoted by the great floral display and the abundant floral reward, intense levels of nectar theft by native insects, and even climatic stress. The reduced size of populations and low fitness settles the grounds for potentially low genetic diversity, inbreeding depression and, ultimately, demographic declines.

Niche complementarity (i.e., complementarity effect) or differences in competitive ability (i.e., selection effect) are the two main mechanisms underlying the biodiversity and ecosystem functioning relationships within a single trophic level. However, few studies have explored such operating mechanisms across multitrophic levels and ecosystem functions, such as pollination. In this large grassland biodiversity study in Inner Mongolia, we partitioned the net biodiversity effect on seed production into the complementarity and selection effects and related these effects to functional diversity and the composition of flowering plant traits, and a range of plant–pollinator network parameters. The positive effect of plant species richness on the complementarity effects overwhelmed the negative effect on the selection effects. Hence, plant diversity positively impacted the net biodiversity effects. In addition, the net biodiversity and complementarity effects were increased in plant communities dominated by species with long inflorescences, suggesting that the facilitative effects of these dominant species attract more pollinators for other species. Furthermore, the complementarity effect increased with decreasing niche overlap of pollinator species, indicating complementary resource use among plant–pollinator interactions. Collectively, our findings highlight the importance of multitrophic interactions in maintaining multitrophic ecosystem functions.

Determining shoot and root biomass and carbon (C) and nitrogen (N) stocks in different ecosystems is crucial to propose adaptative measures to reduce greenhouse gas emission. Data on systems of semiarid areas are scarce, especially irrigated ones. We compared biomasses of four irrigated (bean, maize, grapevine, and mango) and four rainfed livestock systems (buffel grass, prickly pear, gliricidia and leucaena) with those of a preserved and an open tropical dry forest (Caatinga) used as pasture. Caatinga biomass was estimated by allometry and biomasses of the other systems by the destructive method. Root biomasses were determined in layers down to 100 cm. Mango had the highest aboveground and root biomasses: 34.2 and 91.3 Mg ha⁻¹. Preserved Caatinga was the second in aboveground biomass: 25.1 Mg ha⁻¹, compared 9–14.1 Mg ha⁻¹ of the open Caatinga and permanent crops and 3.0–11.8 Mg ha⁻¹ of the grass and annual crops. Preserved Caatinga, gliricidia and buffel grass formed the second group in root biomass (23.7–25.1 Mg ha⁻¹), while all other systems had less than 13.5 Mg ha⁻¹. Preserved and open Caatinga, annual crops and prickly pear had root:shoot ratios below 1, while the other systems had ratios >1, especially mango (2.7). Most systems had roots concentrated in the 0–15 cm layer, but the permanent crops, except prickly pear, concentrated about half of their roots in deeper layers. C (34.2–46.6%) and N (0.6–3.4%) concentrations varied less than biomasses. Root biomass was the plant factor mostly correlated with soil C and N stocks. Therefore, irrigated crops can accumulate more biomass than the native forest, but substitution by mango led to a severe depletion in soil C and N stocks, and all other systems also lost soil C and N. Management strategies such as green manure and crop diversification should be adopted to maintain plant and soil C and N stocks similar to those of the original vegetation.

This study investigates the diet of copper miners at Naḥal ‘Amram (southern Negev Desert), through the examination of the well-preserved remains of plants, mammal and fish bones, dating to the Roman-Byzantine periods (1st–5th centuries CE), recovered during excavations undertaken in three different localities at this mining complex.

Our analyses revealed that the miners enjoyed a varied and nutritious diet, comprising nine species of fruits and vegetables, alongside meat from two domestic animal taxa and representatives of eight different families of fish. While the fish and animal foods were brought to the mines from the Red Sea and neighboring regions, the vegetal food originated from a variety of different sources, some nearby, others quite distant.

We suggest that since copper was traded from Naḥal ‘Amram, the foods arrived at the mines via the same trade routes, from settlements along the ‘Arabah, and these foodstuffs were likely bartered in exchange for copper. The results imply that the people engaged in copper mining were likely a local desert population, Nabataeans, supplementing their food needs from external sources and so enjoying improved nutritional status.

Beyond its findings, the importance of this study lies in the combination of several disciplines, a methodology which can be useful for future research and provide a more reliable understanding of reconstructing the ancient diet.

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.