查看更多>>摘要：Garden plantings in rural villages can affect surrounding natural habitats if non-indigenous and extralimital plant species escape the gardens through dispersal and establishment. Escape from gardens initially occurs via selfseeding. We surveyed woody plant species in roadside gardens in the village of Prince Albert in the arid Karoo region of South Africa to establish which species were being planted and which were self-seeding. We classified plants by origin (non-indigenous, extralimital and locally indigenous and by dispersal structure and recorded microsites where seedlings occurred. Non-indigenous species dominated garden plantings (62% of 1081 individuals and 65% of 92 species) and included 30 legally regulated invasive species. Most (75%) nonindigenous species self-seeded, however 70% of self-seeded individuals were extralimital or locally indigenous species. The best predictor of self-seeding was planting intensity. Self-seeding occurred where supplementary water was available, and seedling density was greater in covered than open sites. Self-seeding did not differ between species with dry and fleshy fruits. The extralimital species Searsia pendulina was a prolific self-seeder and has potential to become invasive. Nurseries should promote locally indigenous plants or extra-limital species that do not self-seed, to reduce the risk of invasions into natural rangeland and riparian areas surrounding villages. [198 words]
Bellusci, AgustinMaldonado, Antoniode Porras, Maria EugeniaBeltrame, Maria Ornela...
1.1-1.10页
查看更多>>摘要：Deserts are unique ecosystems, characterized by extreme conditions and singular biodiversity. The Atacama Desert, South America, is one of the harshest environments on Earth. Rodent middens are valuable archives of desert ecosystems, offering insights into desert ecosystems worldwide. In the last years, rodent middens have been recognized as excellent sources of gastrointestinal parasites in dryland ecosystems. Parasites comprise a large portion of the world's biodiversity, and often play a crucial role in ecosystems. However, there is an overall dearth of knowledge of parasite ecological patterns and processes, especially from deserts. This study aims to investigate gastrointestinal parasite assemblages from current rodent middens across the Atacama Desert, and discuss their distribution at the regional scale. A wide diversity of gastrointestinal parasites was revealed through coproparasitological studies. Eighteen parasitic taxa or morphotypes belonging to Nematoda, Cestoda and Coccidia were identified, and were associated with three rodent families (Chinchillidae, Cricetidae and Octodontidae). Higher parasite richness and number of eggs/oocysts were found at lower-latitude and mid-altitude regions, aligning with the primary productivity patterns of the region. The adaptation of rodents and their parasites to extreme conditions highlights the intricate relationships between species and their environments. This study underscores the value of rodent middens as crucial archives for assessing parasite presence in extreme environments; and emphasizes the importance of considering latitudinal and altitudinal variations in understanding parasite community patterns.
查看更多>>摘要：Tropical savannah ecosystems exhibit high biodiversity, encompassing a range of megafauna, including elephants, lions, ungulates, birds, and insects. While substantial research has been conducted on the ecological dynamics of eastern and southern African savannahs, West African savannahs, particularly within the semi-arid Sudanian and Sahelian biomes, remain understudied. This study assesses the spatial distribution and habitat utilization of 15 large mammal species (mostly ungulates but also three primates and the elephant Loxodonta africana) in Comoe<acute accent>-Le<acute accent>raba National Park, southwestern Burkina Faso, over the period 2010-2018. Data collection employed line transect surveys to estimate ungulate populations, while the Minimum Convex Polygon (MCP) method quantified interannual variations in species occupancy. General Linear Models (GLM) assessed the effects of time and species identity on minimum occupied area. Results indicated no significant temporal variation in species distribution; however, species-specific effects suggested differential habitat preferences. Despite overall spatial stability, variations in poaching indices may have influenced localized species persistence. The reappearance of Loxodonta africana in 2018 underscores the necessity of protecting water-associated habitats and maintaining ecological connectivity. Findings emphasise the need for targeted conservation strategies to sustain biodiversity and mitigate anthropogenic pressures in West African savannahs.
da Silva, Aghata E. M.Franco, Arturo MaciasSolomon, Juan K. Q.da Freiria, Lucien B....
1.1-1.10页
查看更多>>摘要：We investigated the viability of Opuntia ficus indica (or cactus), as nutritional substitute for alfalfa (Medicago sativa) and orchardgrass (Dactylis glomerata) hays, assessing its effects on greenhouse gas emissions, water intake, and water footprint. Fermentation kinetics were assessed using in vitro gas production technique with two ruminally cannulated Angus steers as inoculum donors. Forage types were incubated in serum bottles over three runs for 48 h to analyze fermentation characteristics. In vitro digestion kinetics evaluated cactus forage inclusion at 40%, 60%, 80%, and 100% on a dry matter basis. Computer simulations estimated the of cactus diets on water usage. Data were analyzed as completely randomized design, with diet as fixed and runs as random effects. Results showed cactus reduced CH4 and increased CO2 production higher with cactus compared to hay (P < 0.05). Rumen pH, propionate, and digestibility increased with cactus inclusion, while acetate, isobutyrate, isovalerate, and valerate decreased in orchardgrass diets (P < 0.05). Cactus also reduced water intake and footprint (P < 0.001), offering a viable option to lower methane emissions without affecting cattle performance. Cactus fermentation enhances digestibility and propionate production and produces less methane compared to alfalfa and orchardgrass while still maintaining high dry matter digestibility.
查看更多>>摘要：Anthropogenic change has increased extinction events to an estimated 100 times background rates, amplifying the need for conservation interventions to protect biodiversity. Rare plant research not only provides roadmaps for species protection, but also foundational understanding of how interacting stressors drive decline and the mechanisms by which extinctions occur. Pectis imberbis (Gray) is a recently listed endangered forb found in the biodiverse Sky Island Archipelago in the southwestern U.S. We investigated both intrinsic and extrinsic drivers of decline for this species by relating multiple stressors to vital rates calculated for the nine known P. imberbis populations of sufficient size to allow for demographic analysis. We observed an extraordinary recruitment event in 2022 and concomitantly high population growth across most populations. Despite this, long-term analysis reveals that only two populations have growth rates at or above replacement levels and indicates the importance of stochastic recruitment events in maintaining viability. Climate change is implicated in decline of P. imberbis, though evidence also suggests that browse by ungulates and competition with co-occurring plants depress vital rates. Conservation recommendations vary by population, due to positionality and jurisdictional management, but include reduction of co-occurring stressors, like installing fencing to prevent herbivory, and re-establishment of P. imberbis in climatically suitable areas. Long-term demographic monitoring of this species is warranted to quantify the contribution of stochastic events to viability, examine impacts of interacting stressors, and to project how populations will respond to climate change in this arid, biodiverse region.
Romig, Kirsten B.James, Darren K.Maxwell, Connie J.Bestelmeyer, Brandon T....
1.1-1.11页
查看更多>>摘要：Grassland degradation can hinder global dryland ecosystems with aboveground vegetation a key indicator of transitions from a healthy reference state to undesirable, or degraded states. The soil seed bank may either mirror, or diverge, from its associated aboveground vegetation. To better understand this relationship, we examined vegetation and seed banks across soil types (ecological sites) and vegetation/soil states (ecological states). To assess the soil seed bank, we sampled replicate soil seed bank collections across 67 individual ecological site and state combinations in the northern Chihuahuan Desert U.S.A. We found low species overlap between aboveground vegetation and the soil seed bank ranging from 0% to 30%. Sand dominated ecological sites contained the highest seed densities, yet densities and richness did not differ markedly across most vegetation states within an ecological site. The soil seed bank was dominated by perennial native grasses (>69%) with a low proportion (3%) of shrub seeds. Results indicate that irrespective of degradation levels, functional groups characteristic of historical native grasslands persist in the seed bank. Understanding soil seed bank biodiversity and how it relates to edaphic gradients and degrees of land degradation provides insight into the restoration potential of degraded arid ecosystems in a changing climate.
查看更多>>摘要：Aloe claviflora, widely distributed across the arid regions of southern Africa, remains understudied. In 2016, a population on the Wolwekraal Nature Reserve (113 ha) in the Western Cape, Succulent Karoo Biome, was surveyed to examine size class distribution and floral visitors. The genet population (205) had an inverse-J shape distribution with most genets occurring in the small size class (<0.5-1 m) and fewer occurring in the large size classes. The ramet population (1354), exhibited a typical bell-shaped distribution, with 77% of ramets in 2016 occurring in the reproductive size class. In 2016 and 2021, 33% and 29% of the population produced flowers, respectively, which were visited by birds, reptiles, honeybees, solitary bees, and small mammals. Persistent drought (2015-2021) halted flowering in 2019 and 2020. Browsing by Cape Porcupine was first observed in 2018. Therefore, subsequent surveys conducted in 2019 and 2021 assessed the extent of damage. Since 2016, 62.9% of genets and 39.7% of ramets were destroyed. The data suggest that the animals frequently browsed on reproductive ramets. This study highlights the impact of drought-induced porcupine browsing on A. claviflora survival, underscoring significant changes in porcupine behavior and the resulting population decline of this long-lived, arid-adapted species.
查看更多>>摘要：Land degradation is a global problem, and effective land restoration techniques are needed. The introduction of biocrust has attracted much attention because biocrust-forming organisms have a high survival rate in harsh environments and perform various ecological functions. However, physical disturbances and low water resources impede biocrust development. In degraded areas, soil tackifiers and amendments are often applied before biocrust inoculation, but optimal methods require further research. This study examined whether biomineralization by ureolytic bacteria, one soil stabilization method, could facilitate the growth of biocrust-forming cyanobacteria and biocrust development by improving soil stability and water retention. We incubated cyanobacterial biocrusts on biomineralized sand layers, bare sand, and sand with calcium carbonate powder and, measured indicators of biocrust development, soil stability, and water infiltration. Biomineralization with the biocrust had no effect on water infiltration but improved soil stability. Biomineralization did not significantly facilitate cyanobacterial growth but did improve biocrust structure development. Our findings indicate that biomineralization can enhance the biocrust structure at least in the short term. Longer experiments are needed to clarify the negative aspect of biomineralization on cyanobacterial growth.
查看更多>>摘要：During the protohistoric period, a dominant burial practice in the deserts of the southern Levant involved aboveground, stone-built tombs, associated with the semi-nomadic Timnian cultural entity. This paper examines the characteristics of three distinct grave types from this period, highlighting regional and chronological variations between them. We present data from a newly excavated namus (singular of nawamis) stone-built tomb at the Ashalim site in the Negev Desert, offering an opportunity to explore connections between the Negev and neighboring populations. The Ashalim tomb reveals strong links with burial structures in Sinai to the south, while also reflecting the influence of a broader phenomenon common to the deserts further east-namely, the construction of grave markers.
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NSTL
Elsevier