Phylogenetic structure and formation mechanism of shrub communities in arid and semiarid areas of the Mongolian Plateau

The mechanisms of species coexistence within a community have always been the focus in ecological research. Community phylogenetic structure reflects the relationship of historical processes, regional environments, and interactions between species, and studying it is imperative to understand the formation and maintenance mechanisms of community composition and biodiversity. We studied the phylogenetic structure of the shrub communities in arid and semiarid areas of the Mongolian Plateau. First, the phylogenetic signals of four plant traits (height, canopy, leaf length, and leaf width) of shrubs and subshrubs were measured to determine the phylogenetic conservation of these traits. Then, the net relatedness index (NRI) of shrub communities was calculated to characterize their phylogenetic structure. Finally, the relationship between the NRI and current climate and paleoclimate (since the Last Glacial Maximum, LGM) factors was analyzed to understand the formation and maintenance mechanisms of these plant communities. We found that desert shrub communities showed a trend toward phylogenetic overdispersion; that is, limiting similarity was predominant in arid and semiarid areas of the Mongolian Plateau despite the phylogenetic structure and formation mechanisms differing across habitats. The typical desert and sandy shrub communities showed a significant phylogenetic overdispersion, while the steppified desert shrub communities showed a weak phylogenetic clustering. It was found that mean winter temperature (i.e., in the driest quarter) was the major factor limiting steppified desert shrub phylogeny distribution. Both cold and drought (despite having opposite consequences) differentiated the typical desert to steppified desert shrub communities. The increase in temperature since the LGM is conducive to the invasion of shrub plants into steppe grassland, and this process may be intensified by global warming

Ophthalmology

To characterize the genotypic and phenotypic spectrum of foveal hypoplasia (FH). Multicenter, observational study. A total of 907 patients with a confirmed molecular diagnosis of albinism, PAX6, SLC38A8, FRMD7, AHR, or achromatopsia from 12 centers in 9 countries (n = 523) or extracted from publicly available datasets from previously reported literature (n = 384). Individuals with a confirmed molecular diagnosis and availability of foveal OCT scans were identified from 12 centers or from the literature between January 2011 and March 2021. A genetic diagnosis was confirmed by sequence analysis. Grading of FH was derived from OCT scans. Grade of FH, presence or absence of photoreceptor specialization (PRS+ vs. PRS-), molecular diagnosis, and visual acuity (VA). The most common genetic etiology for typical FH in our cohort was albinism (67.5%), followed by PAX6 (21.8%), SLC38A8 (6.8%), and FRMD7 (3.5%) variants. AHR variants were rare (0.4%). Atypical FH was seen in 67.4% of achromatopsia cases. Atypical FH in achromatopsia had significantly worse VA than typical FH (P < 0.0001). There was a significant difference in the spectrum of FH grades based on the molecular diagnosis (chi-square = 60.4, P < 0.0001). All SLC38A8 cases were PRS- (P = 0.003), whereas all FRMD7 cases were PRS+ (P < 0.0001). Analysis of albinism subtypes revealed a significant difference in the grade of FH (chi-square = 31.4, P < 0.0001) and VA (P = 0.0003) between oculocutaneous albinism (OCA) compared with ocular albinism (OA) and Hermansky-Pudlak syndrome (HPS). Ocular albinism and HPS demonstrated higher grades of FH and worse VA than OCA. There was a significant difference (P < 0.0001) in VA between FRMD7 variants compared with other diagnoses associated with FH. We characterized the phenotypic and genotypic spectrum of FH. Atypical FH is associated with a worse prognosis than all other forms of FH. In typical FH, our data suggest that arrested retinal development occurs earlier in SLC38A8, OA, HPS, and AHR variants and later in FRMD7 variants. The defined time period of foveal developmental arrest for OCA and PAX6 variants seems to demonstrate more variability. Our findings provide mechanistic insight into disorders associated with FH and have significant prognostic and diagnostic value

Can Shallow Plowing and Harrowing Facilitate Restoration of Leymus chinensis Grassland? Results From a 24-Year Monitoring Program

Long-term effects of two mechanical interventions, shallow plowing and harrowing, on degraded Leymus chinensis (Trin.) Tzvel. grassland were studied. Species composition and standing biomass of the grassland were monitored at peak biomass each year for 24 yr after application of these two measures, together with grassland in natural recovery and that under public grazing. Results showed a high resilience of degraded grassland, which recovered naturally after excluding grazing animals to a structure similar to the intact L. chinensis community. In comparison with natural recovery, harrowing facilitated restoration of L. chinensis population and community structure and improved grassland production. Shallow plowing accelerated recovery of L. chinensis population to a larger extent than harrowing and led to a flourish of annual species and improvement of herbage production in the years following its application. But the production improvement was unsustainable and was associated with a decrease in grassland species richness and community complexity. We conclude that the best measure for restoring degraded grassland depends on the restoration objectives and severity of grassland degradation. Harrowing is a feasible technique to assist restoration of the degraded grassland. In contrast, shallow plowing is not appropriate for ecological restoration, but may be applied for quick restoration of herbage production. The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

The inverse texture effect of soil on vegetation in temperate grasslands of China: Benchmarking soil texture effect

The inverse texture effect of soil on vegetation has been reported in a few arid regions, but no information is available on the vast Chinese temperate grassland. In addition, no consistent criteria and approaches have been used to classify soil texture groups, determine the precipitation threshold (Pθ) below which the inverse texture effect occurs, and quantify the effect size (Z), which has limited the generalization of the rules of the soil texture effect in different ecosystems. We analyzed the soil texture effect on vegetation using the remotely sensed vegetation data (MODIS/NDVI) and the Chinese soil profile texture data at 6851 sites in temperate grasslands of China. We found, first, a strong inverse texture effect, i.e., a higher NDVI on coarse- (>50 % sand) than fine-textured soil in low precipitation areas, and Pθ was variable with annual precipitation and averaged 260 mm in the region. Second, we proposed a novel method to use the loam soil as a benchmark against which to quantify the effect of various textured soils, and determine Pθ as the point on precipitation gradient where the soil texture effect shift from positive to negative or vice versa. As such, Pθ decreased with soil coarseness, and increased with precipitation; and the texture effect decreased from positive to negative for sandy soils, whereas it increased from negative to positive for silt or clay soils, on the gradient of precipitation increase. Our results provide new insights into the relations of vegetation pattern and dynamics with precipitation and soil texture, and a method for quantifying and comparing soil texture effect across ecosystem types

Applying a high-precision tracking system to distinguish the spatiotemporal patterns of animal movement in grassland ecology

Spatial heterogeneity in vegetation may derive from variation in animal movement patterns, but these patterns have been difficult to study at the fine spatial and temporal resolutions necessary to relate them to small-scale vegetation patterns. Here, we demonstrated the utility of Ultra-WideBand (UWB) technology to examine animal movement patterns. We evaluated UWB performance in a field setting and illustrated how these data could distinguish movement patterns of different types of livestock during day and night. The data were of high spatial resolution (within 9.7 cm +/- 1.7 cm of actual locations) and high temporal resolution (every second). The positional data clearly demonstrated differential movement patterns between a cow and ewe and between daytime and nighttime. Furthermore, patterns were spatially heterogeneous: the cow spent up to 5% of the day in a single 1 m(2) square and the ewe up to 7.6% of the day in a single square. Over the course of one day, the cow visited about two-thirds of the plot whereas the ewe visited about half of the plot. Our study suggests that UWB technology is a practical tool to describe animal movement at fine spatial and temporal scales. We note some limitations of this technology (battery life, receiver range, and cost) and end by identifying some opportunities for it to improve ecology and conservation, particularly when combined with other data or technologies such as high-resolution vegetation mapping

How Willing Are Herders to Participate in Carbon Sequestration and Mitigation? An Inner Mongolian Grassland Case

Reasonable carbon sequestration and mitigation measures play an important role in reducing greenhouse gas emission and realizing regional sustainable development. How willing herders are to participate in carbon sequestration and mitigation directly determines the corresponding implementation effect. Relevant studies mostly focus on forest households and peasant households, but great uncertainty remains regarding herdsman households. Based on a survey of 404 herdsman households in Inner Mongolian grasslands, this study assessed the cognitive level and participation willingness of herders on carbon sequestration and mitigation of grasslands, and investigated the factors influencing their willingness to participate in the activity. We found that the cognitive level of herders on carbon sequestration and mitigation in Inner Mongolian grasslands was relatively low, with 83% of herdsman households having low cognition and 17% in the state of medium cognition. However, herders are mostly willing to take grassland carbon sequestration and mitigation measures, with 60% of herdsman households being willing to participate, 28% moderately willing to do so, and 12% of unwillingness. This pattern was mainly influenced by the impact of carbon sequestration and mitigation on household income, the economic subsidies and the call for ecological environment protection from the government. The herders tend to be willing to participate when they think that the government calls for ecological environment protection are essential. In contrast, they tend to be unwilling to participate if they think the subsidies too low and the negative effect of sequestration measure on income is essential. We found that the family financial income of herders is a key factor limiting the improvement of participation willingness in this area. It is necessary to improve the cognition of herders for the development of carbon sequestration and mitigation projects

Photosynthesis and metabolite responses of Isatis indigotica Fortune to elevated [CO2]

Climate change is affecting global crop productivity, food quality, and security. However, few studies have addressed the mechanism by which elevated CO2 may affect the growth of medicinal plants. Isatis indigotica Fortune is a widely used Chinese medicinal herb with multiple pharmacological properties. To investigate the physiological mechanism of I. indigotica response to elevated [CO2], plants were grown at either ambient [CO2] (385 μmol mol−1) or elevated [CO2] (590 μmol mol−1) in an open-top chamber (OTC) experimental facility in North China. A significant reduction in transpiration rate (Tr) and stomatal conductance (gs) and a large increase in water-use efficiency contributed to an increase in net photosynthetic rate (Pn) under elevated [CO2] 76 days after sowing. Leaf non-photochemical quenching (NPQ) was decreased, so that more energy was used in effective quantum yield of PSII photochemistry (ΦPSII) under elevated [CO2]. High ΦPSII, meaning high electron transfer efficiency, also increased Pn. The [CO2]-induced increase in photosynthesis significantly increased biomass by 36.8%. Amounts of metabolic compounds involved in sucrose metabolism, pyrimidine metabolism, flavonoid biosynthesis, and other processes in leaves were reduced under elevated [CO2]. These results showed that the fertilization effect of elevated [CO2] is conducive to increasing dry weight but not secondary metabolism in I. indigotica

Assessing the collapse risk of Stipa bungeana grassland in China based on its distribution changes

The criteria used by International Union for Conservation of Nature (IUCN) for its Red List of Ecosystems (RLE) are the global standards for ecosystem-level risk assessment, and they have been increasingly used for biodiversity conservation. The changed distribution area of an ecosystem is one of the key criteria in such assessments. The Stipa bungeana grassland is one of the most widely distributed grasslands in the warm-temperate semi-arid regions of China. However, the total distribution area of this grassland was noted to have shrunk and become fragmented because of its conversion to cropland and grazing-induced degradation. Following the IUCN-RLE standards, here we analyzed changes in the geographical distribution of this degraded grassland, to evaluate its degradation and risk of collapse. Past (1950-1980) distribution areas were extracted from the Vegetation Map of China (1:1,000,000). Present realizable distribution areas were equated to these past areas minus any habitat area losses. We then predicted the grassland's present and future (under the Representative Concentration Pathway 8.5 scenario) potential distribution areas using maximum entropy algorithm (MaxEnt), based on field survey data and nine environmental layers. Our results showed that the S. bungeana grassland was mainly distributed in the Loess Plateau, Hexi Corridor, and low altitudes of the Qilian Mountains and Longshou Mountain. This ecosystem occurred mainly on loess soils, kastanozems, steppe aeolian soils and sierozems. Thermal and edaphic factors were the most important factors limiting the distribution of S. bungeana grassland across China. Since 56.1% of its past distribution area (4.9x10(4) km(2)) disappeared in the last 50 a, the present realizable distribution area only amounts to 2.2x10(4) km(2). But only 15.7% of its present potential distribution area (14.0x10(4) km(2)) is actually occupied by the S. bungeana grassland. The future potential distribution of S. bungeana grassland was predicted to shift towards northwest, and the total area of this ecosystem will shrink by 12.4% over the next 50 a under the most pessimistic climate change scenario. Accordingly, following the IUCN-RLE criteria, we deemed the S. bungeana grassland ecosystem in China to be endangered (EN). Revegetation projects and the establishment of protected areas are recommended as effective ways to avert this looming crisis. This empirical modeling study provides an example of how IUCN-RLE categories and criteria may be valuably used for ecosystem assessments in China and abroad

Photosynthesis and yield response to elevated CO2, C4 plant foxtail millet behaves similarly to C3 species

Foxtail millet (Setaria italica) is a nutrient-rich food source traditionally grown in arid and semi-arid areas, as it is well adapted to drought climate. Yet there is limited information as how the crop responses to the changing climate. In order to investigate the response of foxtail millet to elevated [CO2] and the underlying mechanism, the crop was grown at ambient [CO2] (400 μmol mol−1) and elevated [CO2] (600 μmol mol−1) in an open-top chamber (OTC) experimental facility in North China. The changes in leaf photosynthesis, chlorophyll fluorescence, biomass, yield and global gene expression in response to elevated [CO2] were determined. Despite foxtail millet being a C4 photosynthetic crop, photosynthetic rates (PN) and intrinsic water-use efficiency (WUEi), were increased under elevated [CO2]. Similarly, grain yield and above-ground biomass also significantly increased (P <  0.05) for the two years of experimentation under elevated [CO2]. Increases in seeds and tiller number, spike and stem weight were the main contributors to the increased grain yield and biomass. Using transcriptomic analyses, this study further identified some genes which play a role in cell wall reinforcement, shoot initiation, stomatal conductance, carbon fixation, glycolysis / gluconeogenesis responsive to elevated [CO2]. Changes in these genes reduced plant height, increased stem diameters, and promote CO2 fixation. Higher photosynthetic rates at elevated [CO2] demonstrated that foxtail millet was not photosynthetically saturated at elevated [CO2] and its photosynthesis response to elevated [CO2] were analogous to C3 plants