Benzoic Acid Metabolism and Lipopolysaccharide Synthesis of Intestinal Microbiome Affects the Health of Ruminants under Free-Range and Captive Mode.

It is urgent to explore new ways to protect endangered wild animals and develop sustainable animal husbandry on the Qinghai-Tibet Plateau due to its fragile ecological environment. Ruminants, raised in captivity and free-range, have important niches in the Plateau and are the best models to analyze the effects of different feeding modes on their health. In this study, two ruminants, yaks and goats in free-range and captive modes, respectively, were selected to study the relationship between gut microbes and ruminant health. The results showed that the gut microbial diversity of free-range ruminants was higher than those of captive ruminants. Principal co-ordinates analysis (PCoA) showed that there were significant differences in the gut microbial communities in different breeding modes. Both the captive ruminants enriched the Succinivibrionaceae family, which had a strong potential to synthesize lipopolysaccharide, and the low exercise amount of the captive animals was significantly related to this function. Meanwhile, free-range ruminants enriched Oscillospiraceae, which had the potential to degrade benzoic acid, and this potential had a significant positive correlation with resistance to parasitic infections. We offer other possibilities, such as adding benzoic acid to feed or increasing the exercise time of captive ruminants to make them healthier.

Health Assessment for Mountainous Rivers Based on Dominant Functions in the Huaijiu River, Beijing, China.

Dominant functions usually vary greatly in different reaches of mountainous rivers and are influenced by different adjacent land uses. Assessing river health based on dominant functions is of great practical value to river management. To reveal the health status of different reaches in Beijing's northern mountainous rivers, 60 investigated plots (river length 38.1 km) were surveyed in 2016 in the Huaijiu River, which is a typical mountainous river in northern Beijing, and a hierarchy-comprehensive analysis method was employed. Based on the degree of human influences, the Huaijiu River could be classified into six types, including natural reaches, near-natural reaches, artificial bank plant reaches, artificial bank ornamental plant reaches, artificial bank sparse plant dry-stone reaches and artificial bank masonry reaches. The river health assessment index system was established based on flood control, landscape, hydrology and water quality, and ecological functions. The analytic hierarchy process (AHP) was used to determine the weights of the function layer and indicator layer. The assessment results showed that healthy, subhealthy, slightly damaged, damaged and severely damaged plots accounted for 20.0%, 26.7%, 26.7%, 15.0% and 11.6% of the total plots, respectively. In summary, all plots in natural reaches, artificial bank plant reaches and artificial bank ornamental plant reaches were either healthy, subhealthy or slightly damaged. Plots in artificial bank masonry reaches were either subhealthy, slightly damaged, damaged or severely damaged, accounting for 9.1%, 27.3%, 27.3% and 36.4% of the total plots, respectively. The study proposed a method to assess mountainous river health based on dominant functions, which is a multiobjective approach and is not based solely on natural river functions. The assessment method is appropriate for the socioeconomic development and management of river basins.

Divergences of soil carbon turnover and regulation in alpine steppes and meadows on the Tibetan Plateau.

The grasslands of the Tibetan Plateau store approximately 2.5% of global soil organic carbon (SOC) and considerable soil inorganic carbon (SIC) and have the potential to become a vast carbon source or sink as climate change progresses. However, the soil carbon (C) sequestration mechanisms that occur across large-scale natural gradients remain unclear. Here, humic substances (HS) were utilized to trace soil C turnover at 0-20 cm, and we compared divergences among three main grassland types (alpine meadow, alpine steppe, and artificial plantation) using structural equation modeling (SEM). The results showed that the alpine meadows sequestered the most soil C (63.99 ± 4.41 g kg-1 SOC and 4.11 ± 0.63 g kg-1 SIC), sequestering 2-3 times more than the alpine steppe ecosystems (19.78 ± 1.98 g kg-1 SOC and 9.21 ± 0.66 g kg-1 SIC). The alpine steppe and artificial plantation regions have strong C sink potential due to their low C/N ratios (P < 0.05). Importantly, SIC played an important role in the alpine steppes, accounting for nearly 26-37% of soil C. The ratios of recalcitrant HS to SOC were estimated as 46.50%, 65.09%, and 78.17% in the alpine meadow, alpine steppe, and artificial plantation ecosystems, respectively, indicating that SOC in the alpine meadow was the most sensitive to climate change. Fulvic acid (FA) accounted for 50.86% of SOC in the 0-20-cm interval, contributing most to the formation of SOC in all vegetation types. In addition, in contrast to climatic controls on soil C turnover in the alpine meadow, climate conditions rarely controlled C turnover in the alpine steppe. Moreover, sand and silt were the main soil minerals involved in C turnover in alpine meadow and alpine steppe ecosystems, respectively. Our study improves understanding of the mechanism by which soil C sinks form on the Tibetan Plateau under warming and wetting conditions.

Climate suitability assessment on the Qinghai-Tibet Plateau.

Climate is an important factor that affects livability, but the climate comfort model used for low altitudes is not applicable to high altitudes, and further study on climate suitability in high-altitude areas is needed. In response to the absence of high-altitude characteristics in the current climate comfort assessment methods, this study adds oxygen content and solar radiation as plateau characteristic indicators. We use the consulting graded method (CGM), least squares method (LSM) and questionnaire survey method (QSM) to obtain comprehensive weights for oxygen content, solar radiation and comfort index to build the Climate Suitability Index of Plateau (CSIP) and assess climate suitability on the Qinghai-Tibet Plateau. The CSIP decreases obviously as elevation increases from southeast to northwest on the Qinghai-Tibet Plateau, which means that the climate becomes increasingly unsuitable from southeast to northwest. The Qinghai-Tibet Plateau is divided into four regions-"very unsuitable" (83.8 × 104 km2, 32.4%), "unsuitable" (81.5 × 104 km2, 31.6%), "suitable" (67.9 × 104 km2, 26.3%), and "very suitable" (24.9 × 104 km2, 9.6%)-by the natural break method according to the CSIP. According to the different degrees of response of population density to CSIP, we plot the climate suitability line of the Qinghai-Tibet Plateau to provide basic theoretical support for regional planning in the Qinghai-Tibet region. The CSIP developed in this study provides a new climate suitability assessment method for high-altitude regions and a method for planning human activities on the Qinghai-Tibet Plateau from a climate-focused perspective.

Particulate matter transported from urban greening plants during precipitation events in Beijing, China.

Particulate matter (PM) deposited on canopy surfaces could be washed off and carried in throughfall to the ground. This would help plants recapture airborne PM on their canopy surfaces and then develop a PM purification capacity. Sixteen commonly greening plant species in north China (including 13 arbor species and 3 shrub species) were selected to investigate the washing process of plant-deposited PM during precipitation events. We measured the PM wash-off mass in throughfall under canopies of 16 plant species and in atmospheric precipitation during 14 precipitation events through field positioning experiments in 2015, compared the seasonal changes and species differences in PM wash-off mass, and discussed the predominant factors resulting in the variation. The results showed that plant-deposited PM was largely washed off by precipitation. The average wash-off mass of total suspended particulate (TSP) in throughfall was 1.3 times higher than that in precipitation, at 18.3 ±â€¯0.7 kg hm-2 and 7.9 ±â€¯0.9 kg hm-2, respectively. There were significant seasonal differences in TSP wash-off mass. The value was higher in summer at 22.3 ±â€¯1.0 kg hm-2, followed by that of winter (10.8 ±â€¯0.6 kg hm-2) and spring (8.9 ±â€¯1.0 kg hm-2). TSP wash-off mass in throughfall greatly varied among plant species (F = 9.542, n = 627, p < 0.001). Of the 16 selected species, Platanus acerifolia (38.0 ±â€¯5.8 kg hm-2) showed the largest difference from that of Liriodendron chinese (8.9 ±â€¯0.6 kg hm-2) (n = 80, p < 0.001). PM wash-off mass of different particle sizes in throughfall increased with the increase of event-based precipitation. This study enhanced the quantitative understanding of plant-deposited PM washed-off by natural precipitation among plant species and seasons. The results could provide significant guidelines for the selection and allocation of plant species to improve the PM retention capacity of urban greening plants.

Spatio-temporal variations in PM leaf deposition: A meta-analysis.

Particulate matter (PM) pollution in urban cities is of great concern for public health due to its global and adverse effect of human health while ecosystems function and vegetation control is an effective and eco-friendly way to alleviate PM pollution. We reviewed 150 studies conducted in 15 countries that were published between 1960 and 2016 and used a meta-analysis to examine the time trends and regional differences in leaf deposited PM of urban greening plants. The results suggested that the weekly PM leaf deposition varied markedly with both plant species and space-time and the average value was 1.71 ± 0.05 g m-2·wk-1, and the variations occurred because of vegetation factors, characteristics of the PM source and meteorological factors. Moreover, fine particulate matter accounts for the minimum proportion of the total PM mass but its number ratio is maximum, more than 90% of the total number of particles. This meta-analysis illustrated the spatio-temporal trends and variations in PM leaf deposition and the influencing factors, which provides a scientific basis for the mechanism of PM deposition on leaf surface as well as plant selection and configuration in urban greening.

Influence of vegetation restoration on topsoil organic carbon in a small catchment of the loess hilly region, China.

Understanding effects of land-use changes driven by the implementation of the "Grain for Green" project and the corresponding changes in soil organic carbon (SOC) storage is important in evaluating the environmental benefits of this ecological restoration project. The goals of this study were to quantify the current soil organic carbon density (SOCD) in different land-use types [cultivated land, abandoned land (cessation of farming), woodland, wild grassland and orchards] in a catchment of the loess hilly and gully region of China to evaluate the benefits of SOC sequestration achieved by vegetation restoration in the past 10 years as well as to discuss uncertain factors affecting future SOC sequestration. Based on soil surveys (N = 83) and laboratory analyses, the results show that the topsoil (0-20 cm) SOCD was 20.44 Mg/ha in this catchment. Using the SOCD in cultivated lands (19.08 Mg/ha) as a reference, the SOCD in woodlands and abandoned lands was significantly higher by 33.81% and 8.49%, respectively, whereas in orchards, it was lower by 10.80%. The correlation analysis showed that SOC and total nitrogen (TN) were strongly correlated (R2 = 0.98) and that the average C∶N (SOC∶TN) ratio was 9.69. With increasing years since planting, the SOCD in woodlands showed a tendency to increase; however, no obvious difference was observed in orchards. A high positive correlation was found between SOCD and elevation (R2 = 0.395), but a low positive correlation was found between slope and SOCD (R2 = 0.170, P = 0.127). In the past 10 years of restoration, SOC storage did not increase significantly (2.74% or 3706.46 t) in the catchment where the conversion of cultivated land to orchards was the primary restoration pattern. However, the potential contribution of vegetation restoration to SOC sequestration in the next several decades would be massive if the woodland converted from the cropland is well managed and maintained.