Effects of climate factors and soil properties on soil nutrients and elemental stoichiometry across the Huang–Huai–Hai River Basin,China

Purpose

Soil nutrients, elemental stoichiometry, and their associated environmental control play important roles in nutrient cycling. The objectives of this study were (1) to investigate soil nutrients and elemental stoichiometry, especially potassium and its associative elemental stoichiometry with other nutrients under different land uses in terrestrial ecosystems; (2) to discuss the impacts of climate factors, soil texture, and soil physicochemical properties; and (3) to identify the key factors on soil nutrient levels and elemental stoichiometry.

Materials and methods

Soil data, including pH, bulk density (BD), cation exchange capacity (CEC), volumetric water content (VMC), clay, silt and sand contents, total carbon (TC), nitrogen (TN), phosphorous (TP) and potassium (TK), available nitrogen (AN), phosphorus (AP), potassium (AK), and soil organic matter (SOM) under different land-use types, were collected, and their elemental stoichiometry ratios were calculated. Climate data including temperature, precipitation, relative humidity, wind speed, and evapotranspiration were collected. The least significant difference test and one-way analysis of variance were applied to investigate the variability of soil nutrients and elemental stoichiometry among land-use types; the ordinary least squares method and the general linear model were used to illustrate the correlations between soil nutrients, elemental stoichiometry, and soil properties or climate factors and to identify the key influencing factors.

Results and discussion

Woodlands had the highest SOM, TN, AN, and AK contents, followed by grasslands, croplands, and shrublands, while the TP and TK contents only varied slightly among land-use types. SOM, TN, AN, N/P, and N/K were strongly negatively correlated to soil pH (p <?0.05) and were strongly positively correlated to soil CEC (p <?0.05). For soil texture, only C/N was moderately negatively correlated to silt content but moderately positively correlated to sand content (p <?0.05). For climate factors, SOM, TN, AN, N/P, and N/K were significantly negatively correlated to evapotranspiration and temperature (p <?0.05), and the correlations were usually moderate. Soil pH explained most of the total variation in soil nutrients, and climate factors explained 5.64–28.16% of soil nutrients and elemental stoichiometry (except for AP (0.0%) and TK (68.35%)).

Conclusions

The results suggest that climate factors and soil properties both affect soil nutrients and elemental stoichiometry, and soil properties generally contribute more than climate factors to soil nutrient levels. The findings will help to improve our knowledge of nutrient flux responses to climate change while also assisting in developing management measures related to soil nutrients under conditions of climate change.

     

农机装备综合实验平台管理系统应用

根据实验室业务及质量管理流程，开发了农机装备综合实验平台管理系统，该系统可以将人员、仪器、方法和文件等数据因素有机结合，通过共享平台对大型仪器进行有效整合和共享，并且提供共享服务，实现共享仪器的网上预约、审核等功能。      

Biochar addition mitigates nitrogen loss induced by straw incorporation and nitrogen fertilizer application

Biochar has been shown to be potentially beneficial for enhancing yields and soil properties, and diminishing nitrogen (N) losses. However, it remains unclear how biochar regulates soil carbon (C) and N to mitigate N losses induced by straw mixing with N fertilizer in dryland soils. Therefore, we investigated the effects of straw mixing (S₁), S₁ with biochar (SB) and no straw inputs (S₀), and routine urea application rates (N₁) and 70% of routine rates (N_0.7) on yields and N losses, and identify the relationship between N losses and soil C and N compounds. Results showed that N_0.7 and N₁ were suitable for the maize and wheat seasons, respectively, contributing to mitigating N losses without reducing crop yields. Moreover, in the maize season, N_0.7-SB significantly mitigated the straw-induced NH₃-N and N₂O-N emissions by 106% and 81%, respectively. In the wheat season, N₁-SB reduced the straw-induced NH₃-N and N₂O-N emissions by 35% and 66%, respectively. In addition, N_0.7-SB sharply reduced soil inorganic N (SIN) storage in the maize season. Furthermore, the NH₃-N and N₂O-N emission rates were negatively correlated with dissolved organic carbon/SIN content (0–20 cm) (DOC/SIN_0-20). N losses (N₂O-N and NH₃-N emissions and SIN storage) were positively correlated with SIN_0-20, but negatively correlated with soil organic carbon / SIN_0-20 (SOC/ SIN_0-20). This study provides further evidence that biochar with an appropriate N application rate decreased SIN_0-20 and increased DOC/SIN_0-20, thus reducing SIN storage and the straw-induced gaseous N emissions without decreasing crop yields.     

林木氮素吸收偏好性及其形成机制研究进展

森林土壤中可被林木吸收利用的氮（N）素主要以铵态氮（NH₄+-N）和硝态氮（NO₃--N）的形态存在。受全球气候变暖、氮沉降和人类活动等因素的影响，NH₄+和NO₃-的分布存在很大的时间波动性和空间异质性，且NH₄+-N和NO₃--N亏缺已成为限制林地生产力的主要因素。在森林土壤N亏缺和N异质分布的逆境中，在林木长期进化过程中形成了对不同形态N素的吸收偏好，且这种吸收偏好会随生长环境条件而发生改变。特别是对于NH₄+和NO₃-这2种主要形态的偏好选择性已被证明是决定林木生产力、竞争、共存和生态演替的重要因素之一。对不同树种在N异质分布环境下的N吸收偏好和形成机制的研究，是揭示林木N素营养遗传特性和提高林地N素利用效率的关键。文中从森林土壤中N的主要形态及其分布特征、林木对不同形态N素的吸收偏好和形成机制、林木N吸收偏好的影响因素3个方面进行总结阐述，并对未来研究方向进行展望，以期为我国人工林培育中不同树种的造林配置和合理N素施肥技术提供理论依据和参考。     

运用植被指数时序特征对落叶松人工林分类

为探究植被指数时序特征是否有利于落叶松人工林提取,以孟家岗林场为研究试验区域,根据落叶松人工林季相和物候特征,利用Landsat8OLI影像数据提取研究区内5种植被的归一化植被指数(I NDV)、差值植被指数(I DV)、比值植被指数(I RV)、增强型植被指数(I EV),构建相应的植被指数时序特征。采用最大似然和随机森林两种方法对单一时相影像和加入植被指数时序特征的影像进行对比试验。结果表明:影像中加入植被指数时序特征后,最大似然算法的分类总体精度为89.53%,Kappa系数为0.87,比单一时序特征的影像分类精度提高了13.35%;随机森林算法的森林类型分类总体精度为93.22%,Kappa系数为0.92,比单一时序特征的影像分类精度提高了19.8%。因此,加入植被指数时序特征后能得到更高的落叶松人工林提取精度。     

民国老茶罐里识茶香——记泉祥茶庄的那些事

本文以民国时期较为盛行的茶叶包装为切入点,以"泉祥"老字号茶庄的马口铁茶叶罐为研究对象,通过解读茶叶罐上的图案等蕴含的历史文化信息,梳理了"泉祥"茶庄沉浮起落的发展历程,折射了中国茶文化及工商文化的发展变迁。     

陆地棉自然群体纤维强度性状的全基因组关联分析

纤维强度是衡量棉花纤维品质的重要指标之一。了解棉纤维强度形成的遗传基础对棉花纤维品质的遗传改良具有重要的指导意义。本研究利用83份纤维强度差异显著的陆地棉材料，采用广义线性模型（General linear model, GLM），对5个环境的纤维强度及最佳线性无偏估计值（Best linear unbiased prediction，BLUP）进行全基因组关联分析（Genome-wide association study，GWAS）。结果表明，各环境纤维强度基本符合正态分布，且存在丰富的变异，变异系数为5.55%～8.44%，广义遗传力达到88.67%。GWAS共检测到19个稳定的显著关联SNP位点，分布在A01、A06、D05、D08、D10、D11和D13等7条染色体上，合并为9个数量性状位点（Quantitative trait locus， QTL）区间，其中4个QTL区间与前人定位的QTL区间重叠，其它5个QTL区间是本研究新发现的控制纤维强度性状的稳定位点。根据区间内基因的表达模式及功能注释，共筛选出4个可能与纤维强度相关的候选基因。本研究通过对棉花纤维强度进行全基因组关联分析，为棉花纤维品质性状的分子遗传改良奠定了基础。     

Characterization and pathogenicity of six Cytospora strains causing stem canker of wild apple in the Tianshan Forest,China

Cytospora species are capable of causing destructive cankers of stems belonging to a wide range of woody plant species. In severe cases, cankers may lead to dieback of twigs and branches. Little is known about the Cytospora species causing canker disease of wild apple (Malus sieversii) trees in the Wild Fruit Forest Reserve in Tianshan Forest, Xinjiang Uygur Autonomous Region, China. In this study, six Cytospora isolates belonging to two species were isolated from cankerous lesions of wild apple twigs. Based on multi‐locus phylogenetic analysis using three DNA markers (ITS, tef1‐α and tub2) and morphological characterization, these isolates were identified as Cytospora mali and Cytospora parasitica. Temperature trials (15, 20, 25 and 30°C) showed that the optimal growth temperature for six isolates was 25°C. At a variety of temperatures, C. mali isolates tended to grow faster than isolates of C. parasitica, with the C. mali isolate, EGI1 performing better than others with regard to growth rate. Morphological observations showed that these species exhibited a single locule without conceptacles, and the conidia length was 3–5 μm. In vitro inoculation trials of twigs and leaves of M. sieversii seedlings revealed that the C. mali isolates were highly virulent phytopathogenic fungi, whereas the C. parasitica isolates were less virulent. The isolate EGI1 was the most virulent isolate among the six isolates. This paper presents the first report of pathogenic Cytospora spp. of the M. sieversii Tianshan Wild Fruit Forest Reserve of Yili, Xinjiang in China. It will aid in the understanding of how apple tree cankers are induced and provide disease management guidelines for M. sieversii forest conservation.     

消费者对本地品牌鲜食玉米的购买意愿及其影响因素分析——基于上海929份消费者调查问卷

在农业供给侧结构性改革的时代背景下,通过对上海本地品牌鲜食玉米的购买意愿及其影响因素的实证分析,为更好地推进上海鲜食玉米的品牌建设及为引导本地品牌鲜食玉米的消费提供相应的建议。通过建立多元有序Logit模型定量分析不同消费群体的个体特征、家庭特征、消费群体对鲜食玉米的认知特征及消费者的饮食偏好对上海品牌鲜食玉米产品购买意愿的影响程度和作用方向。结果表明,消费者的性别、年龄、出生地、学历、是否愿意把鲜食玉米当作零食、是否知道上海种植鲜食玉米、对鲜食玉米产品质量安全的信任度及是否在意鲜食玉米的产地,是消费者对本地品牌鲜食玉米购买意愿的显著影响因素。综合来看,当前市场与消费者之间的信息不对称,仍是制约本地品牌发展和高质量农产品消费的重要因素。据此,从消费群体的精准定位、降低市场与消费者间的信息不对称、增加鲜食玉米产品的多样性这几个方面提出针对性的建议。