Amsonia spp. as potential fuel crops for arid lands

The biomass of three desert plants, Amsonia kearneyana, A. grandiflora and A. palmeri, was used for the production of glucose and ethanol by simultaneous saccharification and fermentation techniques. Ethanol yields were 0.46 g g^-1 for A. keurneyana, 0.51 g g^-1 for A. grandiflora and 0.51 g g^-1 for A. palmeri. When the plant materials were saccharified into glucose only, the yields obtained were 0.35 g g^-1 for A. kearneyana, 0.39 g g^-1 for A. grandiflora and 0.22 g g^-1 for A. palmeri.H. Punnapayak is with the Department of Botany, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand; J.J. Hoffmann is with the Bioresources Research Facility, University of Arizona, Tuscon, AZ 85706, USA.     

Plant DNA barcode library for native flowering plants in the arid region of northwestern China

DNA barcoding is a well-established tool for rapid species identification and biodiversity monitoring. A reliable and traceable DNA barcode reference library with extensive coverage is necessary but unavailable for many geographical regions. The arid region in northwestern China, a vast area of about 2.5 million km², is ecologically fragile and often overlooked in biodiversity studies. In particular, DNA barcode data from the arid region in China are lacking. We develop and evaluate the efficacy of an extensive DNA barcode library for native flowering plants in the arid region of northwestern China. Plant specimens were collected, identified and vouchered for this purpose. The database utilized four DNA barcode markers, namely rbcL, matK, ITS and ITS2, for 1816 accessions (representing 890 species from 385 genera and 72 families), and consisted of 5196 barcode sequences. Individual barcodes varied in resolution rates: species- and genus-level rates for rbcL, matK, ITS and ITS2 were 79.9%–51.1%/76.1%, 79.9%–67.2%/88.9%, 85.0%–72.0%/88.2% and 81.0%–67.4%/84.9%, respectively. The three-barcode combination of rbcL + matK + ITS (RMI) revealed a higher species- and genus-level resolution (75.5%/92.1%, respectively). A total of 110 plastomes were newly generated as super-barcodes to increase species resolution for seven species-rich genera, namely Astragalus, Caragana, Lactuca, Lappula, Lepidium, Silene and Zygophyllum. Plastomes revealed higher species resolution compared to standard DNA barcodes and their combination. We suggest future databases include super-barcodes, especially for species-rich and complex genera. The plant DNA barcode library in the current study provides a valuable resource for future biological investigations in the arid regions of China.     

Contrasting management paradigms for pronghorn in the arid Southwest and their northern range: a review

Pronghorn (Antilocapra americana), a symbol of western North America, experienced diverging population trajectories since the mid-twentieth century, with northern populations showing signs of recovery while those in the arid Southwest have struggled to persist. We conducted a systematic literature review of papers published through August 2023 to understand 3 questions. What are the habitat conditions needed for pronghorn to persist? What management actions can be taken to foster higher quality habitat? Do these actions differ for populations in the arid Southwest compared to their northern counterparts? Although the fundamental habitat requirements for pronghorn persistence have remained constant since the early 2000s, it has become clear that precipitation is a key factor influencing pronghorn populations in the arid Southwest. The precise mechanisms by which precipitation influences pronghorn population dynamics are not yet clear, whether through the availability of free water, by affecting forage quality, or indirectly via predator-prey dynamics. Although range-wide forage enhancement may be impractical, providing additional free water sources could facilitate greater movement, enabling pronghorn to access more and higher quality forage and areas with lower predation risk. To clarify how pronghorn persisted for thousands of years in this harsh environment, we must gain a better understanding of their historical metapopulation and migratory behaviors in the arid Southwest.     

New oilseed crops on the horizon

Fats and oils for food uses are now plentiful on a worldwide basis. Tallow, lard and fish oils, as well as vegetable oils, such as those derived from soybean, sunflower, palm, rapeseed, peanut and cottonseed, are often overproduced. Although many of these products are also used for industrial chemicals, they often are not of the most favorable composition for nonfood applications. A search for new oil-seed crops with more advantageous oil composition has led to the development of excellent candidates that are now close to commercial acceptance. Among them areCrambe, Limnanthes, Vernonia, Sapium andSimmondsia. Other crops are at a much lower stage of development but also have excellent potential. They includeCuphea, Foeniculum, Stokesia, Lesquerella andLunaria. In this age of searching for renewable resources to replace petrochemicals and imported strategic materials, a well-organized research and development program on new oilseed crops could soon result in American self-sufficiency for industrial oils and fatty acids.     

Responses of native and migrant desert residents to arid heat

Four groups of Sonoran Desert residents were compared in three studies of heat tolerance. In the first two studies the task involved walking in arid heat at a moderate rate (5 km/hour) for two hours per day over a period of seven consecutive days. The first study compared seven Yaqui Indians with ten Mestizos, all lifelong residents of the same neighborhood in Hermosillo, Sonora. The groups showed no significant differences in physiological responses. The second study compared five Papago Indian students with five White students from Tucson, Arizona. The Papago showed significantly lower sweat rates and significantly lower rectal temperatures. None of the groups showed sequential changes which could be called acclimatization. The lower sweat rate of the Papago is partially the result of their smaller size, but their lower rectal temperatures may represent a more effective heat dissipating mechanism. The third study compared naturally acclimatized Yaquis and Mestizos in hot, humid conditions established by other investigators. These well acclimatized subjects responded in a manner intermediate between the unacclimatized and artificially acclimatized Caucasians reported in the literature. Thus desert acclimatization does not confer maximal acclimatization to humid heat.     

Media optimization and lipid formation of two native diatoms for cultivation in the Southwest Texas desert

Two native diatom isolates belonging to the genus Nitzschia, TAMU-LBK-020 and TAMU-LBK-023, were grown in a chamber simulating summer temperatures and light:dark cycle in the southwest Texas (USA) desert. Different concentrations of macronutrients (Si, N, and P) were tested to identify conditions conducive to growth. Growth rates of the fastest growing treatments exceeded 0.6 doublings per day, with DW and AFDW exceeding 1.0 and 0.8 g L^?1, respectively. Treatments with positive growth were continued to a lipid formation step by omission of Si from the medium in this phase, with lipid accumulation monitored daily by Nile red fluorescence. Peak oil was observed at approximately day 3 for TAMU-LBK-020 and day 5 for TAMU-LBK-023. The highest oil concentrations observed were 17.5?±?7.3 % of AFDW in TAMU-LBK-020 and 28.5?±?5.6 % of AFDW in TAMU-LBK-023 at low N concentrations, but the low N also resulted in growth of 0.2 to 0.5 doublings per day. We propose a biphasic growth strategy, initially under a high macronutrient concentration to promote cell growth and division followed by starving for Si and N to achieve maximal lipid production. However, we anticipate that it will be necessary to determine optimal nutrient concentrations empirically for each species and strain. These results demonstrate that diatoms used for biofuels can achieve fast growth rates and high oil production, and also that native strains, when properly cultured, can be highly suitable for biofuel production, even in harsh climates such as the desert Southwest U.S.     

西北干旱区利用间套作促进能源植物的高产高效

在全球性能源紧缺和我国能源植物大规模种植困难等大背景下,优质、充足的原料供应已成为制约生物质能源产业发展的主要限制因素。在确保能源植物高效生产和克服"与粮争地、与人争粮"现实的同时,挖掘我国边际土壤高产高效生产能源植物的土地优势和增产潜力。通过筛选评价适宜西北干旱地区高抗逆的新型能源植物种类,开发应用能源植物与粮经作物间套作栽培技术,实现新型能源植物对逆境资源的高效利用和可持续规模化种植,提高能源植物的生产力和优化能源物种的区域配置,增加土地产值和农民收入,缓解能源紧缺,达到经济、生态和社会效益多赢,为我国能源和粮食安全提供技术支撑。     

Response of native ungulates to drought in semi‐arid Kenyan rangeland

The distribution and abundance of native ungulates were measured on commercially managed, semi‐arid rangeland in central Kenya over a 3‐year period that encompassed severe drought and above‐average rainfall. Native ungulate biomass density averaged 5282 kg km^?2 over the study and was dominated by elephant (Loxodonta africana), impala (Aepyceros melampus) and dik‐dik (Madoqua kirkii). Biomass density of domestic cattle (Bos taurus) averaged 2280 kg km^?2 during the study. Responses of native ungulates to severe drought were variable. Impala densities were similar to or greater than densities for similar habitat in protected areas, and varied from 12 to 16 km^?2 during and following the drought to 24–29 km^?2 following above‐average rainfall. Dik‐dik densities were also greater than densities reported for protected areas and were surprisingly stable throughout the study despite the wide annual fluctuations in rainfall. Elephant migrated out of the region during drought but were present at high densities (2.9–5.2 km^?2) during wet seasons, consistent with telemetry studies emphasizing the importance of Acacia bushland habitat on commercial rangelands for the migratory portion of the Laikipia–Samburu elephant population. Results show that substantial densities of native browsing and mixed‐feeding ungulates can occur on rangeland managed for commercial beef production and suggest that the capacity for ungulates to move over large spatial scales (>100 km²) and to shift distributions in response to locally variable thunderstorms may be important for sustaining these populations.     

Impact of acid mine-drainage from abandoned spoils on the chemistry of an intermittent stream in the arid Southwest

Drainage from an orphaned copper mine (Sheldon Mine Complex) contributes highly mineralized, acidic waters to Lynx Creek, a small intermittent, arid-climate stream. This results in localized elevation of major cations, silica, sulfate, and heavy metals (Cu, Fe, Mn, Zn), depression in pH, and complete neutralization of bicarbonate alkalinity. Levels of chloride, nitrogen and phosphorus are unaffected by mine-drainage. During stable flow, water quality of the creek improves downstream through precipitation of metal salts, dilution by less mineralized tributaries, and additional buffering from the creek channel and tributaries. Climatic aridity, via high evaporation, concentrates and precipitates metal salts during summertime periods of low flow. Creek sediments thus contain large amounts of heavy metals and phosphorus that are transported downstream in suspended particulates during spates. This reflects an annual cycle of temporary creek-bed storage followed by episodic mobilization toward Lynx Lake, a downstream reservoir. Although the influence of mine drainage is not overtly apparent in the dissolved chemistry of the Lake, high concentrations of metals and phosphorus occur in lake sediments.Represents a portion of a thesis by A. J. L. III submitted in partial fulfillment of the requirements of a M.S. Degree in Botany, Arizona State University.     

Impact of native vegetation cover near crops on the occurrence and molecular diversity of fire ants

Solenopsis invicta and Solenopsis saevissima are the most common fire ants in Brazil. Environmental disturbances favour the colony dispersal of both species, particularly those with an anthropogenic origin. However, the frequencies of the species can vary according to the amount of anthropogenic disturbances. Crops near native vegetation fragments is a common landscape in the Brazilian Atlantic Forest. Here, we analyse if there is influence of native vegetation cover on the occurrence of these fire ants and their molecular diversity in crops. Our hypothesis is that these species are antagonistic in terms of occurrence and molecular diversity when compared in the same habitat. We selected crops near fragments with around 50% of native vegetation cover, a percentage informative enough to detect biological responses from insects belonging to a same order. Nests were collected and the species were identified using external morphology, and mtDNA COI sequences. We reject our hypothesis, which suggest that the species colonize the vegetation patches around crops in a similar way. Solenopsis invicta is not limited by vegetation cover, and has a high haplotype diversity when compared to S. saevissima, particularly when the vegetation cover is greater than 50%. Additionally, the vegetation cover seems to not have influence in the total number of haplotypes, but the species have haplotypes that are exclusive to each landscape. Our findings suggest that S. invicta is expanding to native vegetation areas that it has not occupied before, as S. saevissima was dominant there.     

宁夏中部干旱带不同作物根际土壤真菌群落多样性及群落结构

【背景】宁夏中部干旱带常年缺水,植被稀疏,土地沙漠化严重,生态环境十分脆弱。土地沙漠化导致土地生产力下降,制约着该区农业的发展,因此,改善宁夏中部干旱带农田生态环境具有重要意义。【目的】为该区土地资源的合理利用开发及干旱区土壤真菌多样性的深入研究提供基础数据和理论依据。【方法】运用IlluminaMiSeq高通量测序技术对宁夏中部干旱带农田作物土壤真菌种类进行预测,并对其进行真菌多样性和群落结构的分析。【结果】5个处理中真菌种类均较为丰富,丰富度指数无差异;真菌多样性指数分别以‘张杂谷5号’谷子最高,藜麦的多样性最低,且存在极显著差异。不同作物根际土壤中,子囊菌门(Ascomycota)为最优势菌门,相对丰度为73.00%-89.14%,且远远大于次优势菌门——担子菌门(Basidiomycota,3.9%-16.5%),表现出非常明显的优势;支顶孢属(Acremonium)和裂壳菌属(Schizothecium)为共有的优势菌属。土壤速效磷和土壤碱解氮会对土壤真菌群落结构和功能多样性产生影响,土壤微生物群落结构、功能多样性的变化是土壤理化性质与微生物相互作用的结果。【结论】休闲和种植作物的农田土壤养分均可不同程度的提高,土壤pH降低,真菌群落结构和多样性发生变化。说明合理的土地利用有利于丰富农田土壤微生物群落结构和多样性,改良土壤特性,进而促进该区域土壤生态系统的稳定,提高农田土地资源的合理利用。     

High potential of symbiotic interactions between native mycorrhizal fungi and the exotic tree Eucalyptus camaldulensis for phytostabilization of metal-contaminated arid soils

Waste dumps generated by mining activities contain heavy metals that are dispersed into areas leading to significant environmental contamination. The objectives of this study were (i) to survey native plants and their associated AM fungal communities from waste soils in a Moroccan mine site and (ii) to follow Eucalyptus growth in soil collected from the waste-mine. AM spores from native plant species were collected from the mining site and the surrounding uncontaminated areas were multiplied and inoculated onto Eucalyptus camaldulensis. The results showed that (i) the native plant species recorded in the waste did not show an active metal uptake, (ii) the selected native plant species are associated with AM mycorrhizal fungi and (iii) the use of AM fungi adapted to these drastic conditions can improve the growth of the fast-growing tree, E. camaldulensis and its tolerance to high soil Cu content. In conclusion, it is suggested that in order to define efficient low-cost phytostabilization processes, the use of native resources (i.e., mixtures of native mycorrhizal fungi) in combination with fast-growing tree species such as Eucalyptus, could be used to optimize the establishment of a permanent cover plant in contaminated areas.     

Influence of landscape context on the abundance of native bee pollinators in tomato crops in Central Brazil

Evidence shows that pollinator abundance has declined and, consequently, so has their services, which has possible negative impacts on ecosystem functioning. The goal of this study was to evaluate the influence of landscape context at multiple spatial scales on the abundance of bee pollinators of tomato crops in Brazil. Pollinator abundance was obtained from tomato crops grown in a conventional system in the Cerrado region. Around each tomato field circular buffers of 0.75, 1, 1.5, 2, and 3 km radius were defined. Inside each buffer the landscapes were manually classified into native and non-native cover and, the proportion of native vegetation, the relative largest patch size, and the distance of the nearest native vegetation to each field were calculated. Pollinator species were categorized into five groups: Exomalopsis, Centris, Bombus/Eulaema, Halictidae, and all buzz pollinators combined (Buzzers). The results showed that the landscape context influenced the abundance of the five groups of tomato pollinators. Bees with a smaller body size, such as Exomalopsis spp., responded at smaller scales, while bees with a larger body size, such as the Centris and Bombus/Eulaema groups, responded at larger scales. The abundance of all pollinator groups increased with native vegetation cover. Most groups showed higher abundances in landscapes with similar-size fragments. The results reinforce the recommendation for maintaining natural habitats around crop areas, even if fragmented, for the conservation of the tomato pollinator assemblage. These findings are valuable for planning landscape management in the studied area to improve bee conservation, ecosystem services, and food production.     

Economic native plants of New Zealand

The known and potential uses of New Zealand native plants and the products obtained from them are reviewed. Introduced species are not included.     

Distribution patterns of shrubby N-fixers and non-N fixers in an arid valley in Southwest China: implications for ecological restoration

Shrubs play different key roles in arid regions. Comparisons of shrubs and their site adaptability are essential for correct selection of candidates in developing restoration theory and practice. A survey of topography, soil properties and shrub composition was conducted in fifty-seven 5-m × 5-m plots in an arid valley of the upper Minjiang River, Southwest China. With cluster analysis and critical examinations based on edaphic properties, soil was classified into three groups: dry cinnamon soils (DCS), calcareous cinnamon soils (CCS) and eluvial-accumulation cinnamon soils (EACS). EACS had the highest fertility level, DCS the next and CCS the lowest level. For non-N fixers, soil moisture is the primary limiting factor, and nitrogen the next. However, N-fixers are weakly constrained by soil moisture and nitrogen, the extent of which is species-specific. N-fixers had a significantly higher cumulative relative importance value (44.4%) in CCS than in DCS (34.0%) and EACS (17.3%). The results suggest that it would be reasonable to restore non-N fixers in DCS and EACS and that N-fixers are appropriate for CCS. Compared with grass, shrubs significantly enhanced the availability of nitrogen and phosphorus and soil electric conductivity, and significantly decreased the soil C/N ratio. The median fertility level of soil dominated by N-fixers indicates that N-fixers are suitable driver candidates from grassland to non-N-fixing shrub land. Four native shrubby legumes (Indigofera amblyantha, Sorphora viciifolia, Desmodium podocarpum and Bauhinia faberivar) and one soil-conserving shrub (Ajania potaninii) are the top-priority pioneers for ecological restoration.     

Native cover crops suppress exotic annuals and favor native perennials in a greenhouse competition experiment

In a greenhouse experiment, we examined the effectiveness of four native cover crops for controlling four exotic, invasive species and increasing success of four western North American grassland species. Planting the annual cover crops, annual ragweed (Ambrosia artemisiifolia) and common sunflower (Helianthus annuus), reduced the biomass of the exotic species cheatgrass (Bromus tectorum), Japanese brome (Bromus japonicus), Canada thistle (Cirsium arvense), and whitetop (Cardaria draba). The annual cover crops also reduced the desired species biomass in competition with the perennial exotics, but either increased or did not affect the desired species biomass in competition with the annual exotics. Planting the perennial cover crops, Canada goldenrod (Solidago canadensis) and littleleaf pussytoes (Antennaria microphylla), rarely inhibited exotic species, but did increase the desired species biomass. Field experiments are needed to test the cover crops under more ecologically relevant conditions, but our results suggested that the annual cover crops may be effective for controlling invasive annuals and for facilitating native perennials.