The Low Congruence between Plant and Animal Diversity in Field Ridges of Intensively Managed Paddy Landscapes, China.

Field ridges are commonly viewed as the stable semi-natural habitats for maintaining plant diversity in the agricultural landscape. The high plant diversity could further support higher animal diversity. But following the adoption of well-facilitated farmland construction measures in China, many field ridges have been disproportionately neglected or destroyed. Empirical studies delineating the relationships between plant and animal diversity in these field ridges in the paddy landscape remain scant, especially in China, which has the most rice production. A two-year field ridge evaluation was conducted in the Chengdu Plain area, covering 30 paddy landscapes. This investigation scrutinizes the shape attributes of field ridges, their plant diversity, and the associated animal α-diversity and community compositions, including spiders, carabids, birds, frogs, and rice planthoppers. In the results of Pearson's correlation analysis, a significant inconsistent correlation was observed between plant diversity and animal diversity. The analysis of community structure heterogeneity also revealed no correspondence for species composition between plant and animal communities (i.e., spiders, carabids, and birds), while the non-metric multidimensional scale analysis indicated a substantial difference in the species composition of spiders or plants even within the same field ridge between 2020 and 2021. We argue that the implementation of intensive management practices in paddy landscapes, such as machine ploughing and harvesting and herbicide spraying with drones, leads to a scarcity of stable animal and plant communities in field ridges. Therefore, besides retaining these field ridges in paddy landscapes, maintaining the long-term stable ridges by refraining from herbicide spraying or artificial weeding, as well as avoiding winter wheat cultivating in field ridges, will contribute to protecting biodiversity of field ridges as semi-natural habitats.

Straw mulch improves soil carbon and nitrogen cycle by mediating microbial community structure and function in the maize field.

This study was conducted to investigate the capability of the microbial community characteristics and soil variables to promote carbon and nitrogen cycles in maize fields under straw mulch. We covered the surface soil of the maize field with different amounts of wheat straw (0 kg/ha, 2,250 kg/ha, and 4,500 kg/ha) and used 16S rRNA and ITS sequencing, Biology ECO-plate, traditional enzymology, TOC analyzer, and HPLC to measure bacterial and fungal community composition and functions, characteristics of microbial carbon source metabolism, carbon and nitrogen fraction, enzyme activity, and organic acid content in the maize rhizosphere and non-rhizosphere. The results indicated that short-term straw mulch insignificantly affected the alpha diversity of bacterial and fungal communities whereas significantly influenced their beta diversity. The results of functional prediction revealed that straw mulch considerably boosted the relative abundances of bacteria belonging to chemoheterotrophy, aerobic chemoheterotrophy, ureolysis, and nitrogen fixation and inhibited fermentation and nitrate reduction in maize rhizosphere soil. These processes primarily drove the C and N cycles in soil. Straw mulch also improved fungal saprotrophs by raising the proportion of Chaetomiaceae and Chaetosphaeriaceae. The Biology ECO-plate results illustrated that straw mulch weakened the metabolism capacity of microbial labile carbon resources. As a result, the labile C and N fractions were raised under straw mulch. Our results also showed that straw mulch primarily regulated the microbial community structure in rhizosphere soil by significantly decreasing Firmicutes and Ascomycota relative abundance while increasing Basidiomycota. The fungal community structure is more than bacterial for affecting soil microbial biomass carbon, readily oxidizable organic carbon, dissolved organic carbon, available nitrogen, ammonium, and nitrate directly and indirectly through malic acid content and cellulase, protease, and amylase activity. Overall, our findings imply that straw mulch might influence the bacterial and fungal community structures, thereby boosting the production of labile C and N components and accelerating the C and N cycle in maize fields.

Potassium Improves Drought Stress Tolerance in Plants by Affecting Root Morphology, Root Exudates and Microbial Diversity.

Potassium (K) reduces the deleterious effects of drought stress on plants. However, this mitigation has been studied mainly in the aboveground plant pathways, while the effect of K on root-soil interactions in the underground part is still underexplored. Here, we conducted the experiments to investigate how K enhances plant resistance and tolerance to drought by controlling rhizosphere processes. Three culture methods (sand, water, and soil) evaluated two rapeseed cultivars' root morphology, root exudates, soil nutrients, and microbial community structure under different K supply levels and water conditions to construct a defensive network of the underground part. We found that K supply increased the root length and density and the organic acids secretion. The organic acids were significantly associated with the available potassium decomposition, in order of formic acid > malonic acid > lactic acid > oxalic acid > citric acid. However, the mitigation had the hormesis effect, as the appropriate range of K facilitated the morphological characteristic and physiological function of the root system with increases of supply levels, while the excessive input of K could hinder the plant growth. The positive effect of K-fertilizer on soil pH, available phosphorus and available potassium content, and microbial diversity index was more significant under the water stress. The rhizosphere nutrients and pH further promoted the microbial community development by the structural equation modeling, while the non-rhizosphere nutrients had an indirect negative effect on microbes. In short, K application could alleviate drought stress on the growth and development of plants by regulating the morphology and secretion of roots and soil ecosystems.

Risk of Rupture of Small Intracranial Aneurysms (≤5 mm) Among the Chinese Population.

OBJECTIVE: We sought to develop a model to predict the risk of small intracranial aneurysm (SIA; ≤5 mm) rupture among Chinese adults and to compare the score predicted by our model with the PHASES (population, hypertension, age, size, earlier subarachnoid hemorrhage, aneurysm site) score. METHODS: From August 2011 to June 2015, 366 patients with 394 SIAs were retrospectively evaluated and followed up for ≥5 years. The clinical characteristics of the patients were reviewed from their medical records, and the SIA features were evaluated from the imaging studies. The independent risk factors for SIA rupture were studied using multiple Cox proportional hazards regression analysis. The diagnostic value of the PHASES score for the prediction of SIA rupture was also calculated. RESULTS: Six SIAs in 6 different patients had ruptured during a mean follow-up of 6.4 years. An irregular shape (odds ratio [OR], 31.464), a high aspect ratio (OR, 40.573), and a high size ratio (OR, 20.541) increased the risk of rupture. The predictive score incorporated these three factors. The threshold was 1.5, and the area under the curve, sensitivity, and specificity were 0.986, 100%, and 94.6%, respectively. For the PHASES score, the area under the curve, sensitivity, and specificity were 0.702, 83.3%, and 62.1%, respectively. CONCLUSIONS: An irregular shape, a high aspect ratio, and a high size ratio were associated with SIA rupture in the Chinese population. Our predictive score is of great value in predicting the risk of SIA rupture.

[Spider diversity and community characteristics in cropland and two kinds of recovery habitats in Bashang area, China]. / åä¸Šåœ°åŒºå†œç”°åŠä¸¤ç§æ¢å¤ç”Ÿå¢ƒä¸­èœ˜è››å¤šæ ·æ€§ä¸Žç¾¤è½ç‰¹å¾.

Spiders are important natural enemies in agricultural ecosystems. The biodiversity and community characteristics of spider directly determine the quality of ecosystem services such as pest control in cropland. Cropland and its surrounding recovery habitats are important for spiders. We used trap method to examine species composition, species diversity, and functional characteristics of spider communities at three altitudes (871, 1360 and 1635 m) and three habitats (cropland, natural recovery grassland, artificial restoration woodland) in Chongli District, Zhangjiakou, Hebei Province, China. The results showed that diversity index of different habitats was significantly diffe-rent. The abundance of spiders in artificial restoration woodland was 124.3, which was significantly higher than that in natural recovery grassland (70.1) and cropland (38.6). Species richness of artificial restoration woodland (16.3) and natural recovery grassland (21.4) were not significantly different, but both were significantly higher than those of cropland (8.9). The Shannon diversity index of artificial restoration woodland (2.04) and natural recovery grassland (2.05) was not significantly different, and both were significantly higher than that of cropland (1.55). There were significant differences in community composition among all three habitats. Spider body length was positively correlated with spider hunting types. Large spiders tended to get food by hunting. Natural recovery grassland and cropland spiders were dominated by safari, and artificial restoration woodland with more web-forming spiders. Spiders at higher altitude were generally small. Both natural recovery grassland and artificial restoration woodland could increase spider diversity and played important roles in regional biodiversity protection. Spider community composition differentiated in different habitats, with the overall functional characteristics of spider communities being changed and some habitats being retained. The index of spider diversity of the two recovery habitats was higher than that of cropland habitats, with differences in the species composition of the two recovery habitats, both of which had the function of protecting endemic species. Our results were useful for the protection and restoration of spider biodiversity on cropland and regional scales.

Effect of controlled-release urea fertilizers for oilseed rape (Brassica napus L.) on soil carbon storage and CO2 emission.

Fertilizer-induced CO2 emission is a primary driver of global warming. The experiment was used to study whether controlled-release urea (CRU) application in winter oilseed rape can play a positive role in mitigating CO2 emission and promoting C utilization by soil microorganisms. Five fertilizer types consisted of N0 (0 g N plant-1), conventional CRU application (CRU100%), monotypic CRU at the 80% of conventional rate (CRU80%), co-application of CRU with uncoated urea (CRC), and organic fertilizer (CRO). Results showed that soil CO2 fluxes were significantly affected by N fertilizer types after the start of the stem growing (P < 0.05). CO2 emissions typically peaked during the seed filling period, with the highest emission of 1.99 µmol m-2 s-1 being registered for CRU100%. CRU100% had 25.00%, 30.60%, and 4.17% greater CO2 emissions than CRU80%, CRC, and CRO practices by harvest, respectively. Compared to the conventional CRU treatment, CRU80% led to a lower root volume and root mass ratio than CRU100%, which could partly contribute to the reduced CO2 emission. Conversely, CRU80% performed better in N agronomic efficiency than that of CRU100% treatment. Also, C source utilization by soil microbiomes as well as microbial diversity indices following CRU80% along with CRO applications was substantially higher than that under the conventional CRU supply. These observations suggest that opportunity exists to maintain N balance by N fertilization practices to mitigate CO2 emission from cropland. Further, a close and positive relationship between soil total nitrogen and CO2 emission also supports this. CRO-treated soils substantially elevated the contents of total carbon and readily oxidation carbon over CK. Moreover, the enzyme activity of ß-glucosidase in CRO soil was about twice as high as the CRU100%. Consequently, CRU amendments by decreasing CRU rate application and the incorporation of organic fertilizer into CRU have the potential for mitigating of CO2 emission and positive effect on the soil microbial functional diversity to improve nitrogen use efficiency of rapeseed.

Effects of Biochar Combined with Nitrogen Fertilizer Reduction on Rapeseed Yield and Soil Aggregate Stability in Upland of Purple Soils.

Reduction of soil fertility and production efficiency resulting from excessive application of chemical fertilizers is universal in rapeseed-growing fields. The main objective of our study was to assess the effects of biochar combined with nitrogen fertilizer reduction on soil aggregate stability and rapeseed yield and to identify the relationship between yield and soil aggregate stability. A two-factor field experiment (2017-2019) was conducted with biochar (0 (C0), 10 (C10), 20 (C20) and 40 t·ha-1 (C40)) and nitrogen fertilizer (180 (N100), 144 (N80) and 108 kg N·ha-1 (N60)). Experimental results indicated that under N100 and N80 treatments, C10 significantly increased the macro-aggregates (R0.25), mean weight diameter (MWD) and geometric mean diameter (GMD) of soil water stable aggregate by 14.28%-15.85%, 14.88%-17.08% and 36.26%-42.22%, respectively, compared with C0. Besides, the overall difference of the soil water-stable aggregate content in 2-5 mm size range among nitrogen treatments was significant under the application of C10, which increased by 17.04%-33.04% compared with C0. Total organic carbon (TOC) in R0.25 of soil mechanical-stable aggregates was basically all increased after biochar application, especially in 0.25-1 mm and 1-2 mm aggregates, and had an increasing trend with biochar increase. C10 significantly increased rapeseed yield by 22.08%-45.65% in 2019, compared with C0. However, the reduction of nitrogen fertilizer reduced the two-year average rapeseed yield, which decreased by 11.67%-31.67% compared with N100. The highest yield of rapeseed was obtained by N100C10 in two consecutive years, which had no statistical difference with N80C10. However, the two-year yields of N80C10 were all higher than those of N100C0 with increase rate of 16.11%, and which would reduce 35.43% nitrogen fertilizer in the case of small yield difference, compared with the highest yield (2.67 t·ha-1) calculated by multi-dimensional nonlinear regression models. The regression analysis indicated R0.25, MWD and GMD had the strong positive associations with rapeseed yield, whereas percentage of aggregate destruction (PAD0.25) had a significant negative correlation with rapeseed yield. This study suggests that the application of biochar into upland purple soil could improve soil structure, increase the content of TOC in macro-aggregates under nitrogen fertilizer reduction as well as replace part of nitrogen fertilizer to achieve relatively high rapeseed yield.

The influence of landscape alterations on changes in ground beetle (Carabidae) and spider (Araneae) functional groups between 1995 and 2013 in an urban fringe of China.

Urbanization is one of the main causes of land use change, especially from 1990 to now in China, but knowledge of its effect on different functional groups of carabids and spiders in the adjacent rural areas over time remains limited. We assessed whether landscape alterations (1993 versus 2013) drove changes in carabid and spider functional groups (1995 versus 2013) in an agricultural landscape located on the fringe of a rapidly growing city in China. Although built-up land increased from 6.3% to 32% across the whole landscape, the overall species richness of carabids and spiders did not decline. In contrast to the reduction in species richness of large carabids, the species richness of small carabids increased. Species richness of both large and small spiders increased. The species composition of carabids and spiders significantly changed between 1995 and 2013. Species compositions of large, predatory carabids and large or ground-hunting spiders were more sensitive to the changes in built-up land than those of small, omnivorous carabids and small or web-building spiders. The amount of grassland (abandoned land covered by wild grass) also increased as farmers began to work in the city. The increased grassland significantly contributed to the increased species richness of predatory and macropterous carabids. However, increased landscape diversity did not affect species richness of either carabids or spiders. High landscape diversity was related to reduction in field size, resulting in a decrease in the mean body size of carabids. This indicates that evaluating the effect of landscape change on carabid and spider diversity should be based on their functional traits. Different taxa, even different functional groups, have different responses to landscape change. The increase in built-up land did not immediately reduce species richness at the urban fringe. Increasing wild grasslands and combining smaller fields may benefit farmland biodiversity in this region.

Disentangling effects of abiotic factors and biotic interactions on cross-taxon congruence in species turnover patterns of plants, moths and beetles.

High cross-taxon congruence in species diversity patterns is essential for the use of surrogate taxa in biodiversity conservation, but presence and strength of congruence in species turnover patterns, and the relative contributions of abiotic environmental factors and biotic interaction towards this congruence, remain poorly understood. In our study, we used variation partitioning in multiple regressions to quantify cross-taxon congruence in community dissimilarities of vascular plants, geometrid and arciinid moths and carabid beetles, subsequently investigating their respective underpinning by abiotic factors and biotic interactions. Significant cross-taxon congruence observed across all taxon pairs was linked to their similar responses towards elevation change. Changes in the vegetation composition were closely linked to carabid turnover, with vegetation structure and associated microclimatic conditions proposed causes of this link. In contrast, moth assemblages appeared to be dominated by generalist species whose turnover was weakly associated with vegetation changes. Overall, abiotic factors exerted a stronger influence on cross-taxon congruence across our study sites than biotic interactions. The weak congruence in turnover observed particularly between plants and moths highlights the importance of multi-taxon approaches based on groupings of taxa with similar turnovers, rather than the use of single surrogate taxa or environmental proxies, in biodiversity assessments.

[Spatial distribution pattern of carabid assemblage in agricultural landscape of Miyun County, Beijing].

By the method of pitfall trap sampling, an investigation was conducted on the carabid assemblage in four typical habitats (maize field, peanut field, orchard, and semi-natural woodland) in the agricultural landscape in Xitiange Village of Miyun County, Beijing. Among the four habitats, orchard had the highest alpha-diversity of carabid assemblage, followed by woodland and maize field, and peanut field had the lowest one. The species composition of the assemblage in woodland, peanut field, and orchard had evident difference, but was similar to that in maize field to some extent. The number of the individuals of predatory and omnivorous carabid sub-assemblages was larger in orchard, and the predatory sub-assemblage presented more distinct difference in its species turnover rate than the omnivore sub-assemblage among the habitats. This study showed that low-intensively managed orchard habitat could sustain higher alpha-diversity of carabid assemblage than semi-natural woodland habitat, and the landscape with diversified habitats could benefit the beta-diversity of carabid assemblage and its predatory sub-assemblage. To attach importance to the conservation of diversified habitats and low-intensively managed farmland habitat would have significance for the conservation of carabid assemblage diversity and its pest control function in agricultural landscape.

[Diversity of geometrid moth (Lepidoptera: Geometridae) in cropland and reforested semi-natural habitats at different altitudes of Bashang Plateau, Hebei Province of China].

In order to understand the effects of landscape heterogeneity induced by habitat restoration and landform change on the biodiversity in degraded landscapes, an investigation by using light trap was conducted on the geometrid moth (Lepidoptera: Geometridae) diversity in the cropland and reforested semi-natural habitats in three villages at different altitudes of Bashang Plateau in 2006 and 2007. There existed significant differences in the species richness and individual number of geometrid moth between cropland and reforested semi-natural habitats and in the species richness of geometrid moth between the villages at different altitudes, but no significant differences in the individual number of geometrid moth between the villages at different altitudes and in the standardized sparseness index and Fisher' s alpha index between the villages and between the cropland and reforested semi-natural habitats within each village. The non-metric multi-dimensional scaling (NMDS) indicated that the community structure of geometrid moth in different habitats and at different altitudes differed significantly. This study indicated that the landscape heterogeneity induced by land-form change had significant effects on the community structure and diversity of geometrid moth on Bashang Plateau, and, both cropland and reforested semi-natural habitats were the important habits for geometrid moth. It was suggested that to protect the landscape mosaics containing cropland and reforested semi-natural habitats across the varied landform of Bashang Plateau would have significances in the conservation of high gamma-diversity of geometrid moth, but whether the reforestation and creation of semi-natural habitats could improve the biodiversity of geometrid moth should be monitored in long term.