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  • Effects of drip and flood irrigation on carbon dioxide exchange and crop growth in the maize ecosystem in the Hetao Irrigation District, China

    分类: 农、林、牧、渔 >> 农业基础学科 提交时间: 2024-02-21 合作期刊: 《干旱区科学》

    摘要: Drip irrigation and flood irrigation are major irrigation methods for maize crops in the Hetao Irrigation District, Inner Mongolia Autonomous Region, China. This research delves into the effects of these irrigation methods on carbon dioxide (CO2) exchange and crop growth in this region. The experimental site was divided into drip and flood irrigation zones. The irrigation schedules of this study aligned with the local commonly used irrigation schedule. We employed a developed chamber system to measure the diurnal CO2 exchange of maize plants during various growth stages under both drip and flood irrigation methods. From May to September in 2020 and 2021, two sets of repeated experiments were conducted. In each experiment, a total of nine measurements of CO2 exchange were performed to obtain carbon exchange data at different growth stages of maize crop. During each CO2 exchange measurement event, CO2 flux data were collected every two hours over a day-long period to capture the diurnal variations in CO2 exchange. During each CO2 exchange measurement event, the biological parameters (aboveground biomass and crop growth rate) of maize and environmental parameters (including air humidity, air temperature, precipitation, soil water content, and photosynthetically active radiation) were measured. The results indicated a V-shaped trend in net ecosystem CO2 exchange in daytime, reducing slowly at night, while the net assimilation rate (net primary productivity) exhibited a contrasting trend. Notably, compared with flood irrigation, drip irrigation demonstrated significantly higher average daily soil CO2 emission and greater average daily CO2 absorption by maize plants. Consequently, within the maize ecosystem, drip irrigation appeared more conducive to absorbing atmospheric CO2. Furthermore, drip irrigation demonstrated a faster crop growth rate and increased aboveground biomass compared with flood irrigation. A strong linear relationship existed between leaf area index and light utilization efficiency, irrespective of the irrigation method. Notably, drip irrigation displayed superior light use efficiency compared with flood irrigation. The final yield results corroborated these findings, indicating that drip irrigation yielded higher harvest index and overall yield than flood irrigation. The results of this study provide a basis for the selection of optimal irrigation methods commonly used in the Hetao Irrigation District. This research also serves as a reference for future irrigation studies that consider measurements of both carbon emissions and yield simultaneously.

  • Effects of landscape fragmentation of plantation forests on carbon storage in the Loess Plateau, China

    分类: 农、林、牧、渔 >> 林学 提交时间: 2024-02-21 合作期刊: 《干旱区科学》

    摘要: Tree plantation and forest restoration are the major strategies for enhancing terrestrial carbon sequestration and mitigating climate change. The Grain for Green Project in China has positively impacted global carbon sequestration and the trend towards fragmentation of plantation forests. Limited studies have been conducted on changes in plantation biomass and stand structure caused by fragmentation, and the effect of fragmentation on the carbon storage of plantation forests remains unclear. This study evaluated the differences between carbon storage and stand structure in black locust forests in fragmented and continuous landscape in the Ansai District, China and discussed the effects of ecological significance of four landscape indices on carbon storage and tree density. We used structural equation modelling to explore the direct and indirect effects of fragmentation, edge, abiotic factors, and stand structure on above-ground carbon storage. Diameter at breast height (DBH) in fragmented forests was 53.3% thicker, tree density was 40.9% lower, and carbon storage was 49.8% higher than those in continuous forests; for all given DBH>10 cm, the trees in fragmented forests were shorter than those in continuous forests. The patch area had a negative impact on carbon storage, i.e., the higher the degree of fragmentation, the lower the density of the tree; and fragmentation and distance to edge (DTE) directly increased canopy coverage. However, canopy coverage directly decreased carbon storage, and fragmentation directly increased carbon storage and tree density. In non-commercial forests, fragmentation reduces the carbon storage potential of plantation, and the influence of patch area, edge, and patchy connection on plantation should be considered when follow-up trees are planted and for the plantation management. Thus, expanding the area of plantation patches, repairing the edges of complex-shaped patches, enhancing the connectivity of similar patches, and applying nutrients to plantation forests at regular intervals are recommended in fragmented areas of the Loess Plateau.

  • Ecological effect of the plantation of Sabina vulgaris in the Mu Us Sandy Land, China

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2024-01-12 合作期刊: 《干旱区科学》

    摘要: Vegetation restoration through artificial plantation is an effective method to combat desertification, especially in arid and semi-arid areas. This study aimed to explore the ecological effect of the plantation of Sabina vulgaris on soil physical and chemical properties on the southeastern fringe of the Mu Us Sandy Land, China. We collected soil samples from five depth layers (0–20, 20–40, 40–60, 60–80, and 80–100 cm) in the S. vulgaris plantation plots across four plantation ages (4, 7, 10, and 16 years) in November 2019, and assessed soil physical (soil bulk density, soil porosity, and soil particle size) and chemical (soil organic carbon (SOC), total nitrogen (TN), available nitrogen (AN), available phosphorus (AP), available potassium (AK), cation-exchange capacity (CEC), salinity, pH, and C/N ratio) properties. The results indicated that the soil predominantly consisted of sand particles (94.27%–99.67%), with the remainder being silt and clay. As plantation age increased, silt and very fine sand contents progressively rose. After 16 years of planting, there was a marked reduction in the mean soil particle size. The initial soil fertility was low and declined from 4 to 10 years of planting before witnessing an improvement. Significant positive correlations were observed for the clay, silt, and very fine sand (mean diameter of 0.000–0.100 mm) with SOC, AK, and pH. In contrast, fine sand and medium sand (mean diameter of 0.100–0.500 mm) showed significant negative correlations with these indicators. Our findings ascertain that the plantation of S. vulgaris requires 10 years to effectively act as a windbreak and contribute to sand fixation, and needs 16 years to improve soil physical and chemical properties. Importantly, these improvements were found to be highly beneficial for vegetation restoration in arid and semi-arid areas. This research can offer valuable insights for the protection and restoration of the vegetation ecosystem in the sandy lands in China.
     

  • Parkland trees on smallholder farms ameliorate soil physical-chemical properties in the semi-arid area of Tigray, Ethiopia

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2024-01-12 合作期刊: 《干旱区科学》

    摘要: Proposed agroforestry options should begin with the species that farmers are most familiar with, which would be the native multipurpose trees that have evolved under smallholder farms and socioeconomic conditions. The African birch (Anogeissus leiocarpa (DC.) Guill. & Perr.) and pink jacaranda (Stereospermum kunthianum Cham.) trees are the dominant species in the agroforestry parkland system in the drylands of Tigray, Ethiopia. Smallholder farmers highly value these trees for their multifunctional uses including timber, firewood, charcoal, medicine, etc. These trees also could improve soil fertility. However, the amount of soil physical and chemical properties enhanced by the two species must be determined to maintain the sustainable conservation of the species in the parklands and to scale up to similar agro- ecological systems. Hence, we selected twelve isolated trees, six from each species that had similar dendrometric characteristics and were growing in similar environmental conditions. We divided the canopy cover of each tree into three radial distances: mid-canopy, canopy edge, and canopy gap (control). At each distance, we took soil samples from three different depths. We collected 216 soil samples (half disturbed and the other half undisturbed) from each canopy position and soil depth. Bulk density (BD), soil moisture content (SMC), soil organic carbon (SOC), total nitrogen (TN), available phosphorus (AP), available potassium (AK), pH, electrical conductivity (EC), and cation exchange capacity (CEC) were analysed. Results revealed that soil physical and chemical properties significantly improved except for soil texture and EC under both species, CEC under A. leiocarpus, and soil pH under S. kunthianum, all the studied soils were improved under both species canopy as compared with canopy gap. SMC, TN, AP, and AK under canopy of these trees were respectively 24.1%, 11.1%, 55.0%, and 9.3% higher than those soils under control. The two parkland agroforestry species significantly enhanced soil fertility near the canopy of topsoil through improving soil physical and chemical properties. These two species were recommended in the drylands with similar agro-ecological systems.

  • 《齐民要术》中的南方因素

    分类: 农、林、牧、渔 >> 农业史 提交时间: 2023-12-29

    摘要: 北魏贾思勰撰著的《齐民要术》是中国传统农学经典中的经典,也是研究中国古代史的重要史料。该书共十卷,除第十卷标题为“五谷、果蓏、菜茹非中国物产者”外,言下之意,前九卷所载之内容,当属北魏统治下的所谓“中国”之物产。因而,《齐民要术》也被认为是反映中国古代黄河流域农业的农学著作,即北方农书。但细检书中内容,却发现书中包含有许多非典型性北方因素,如,稻、鱼、竹、橘、莼、莲、芡、芰、菰、菘、姜、杬、越瓜、山石榴(杜鹃花)、水牛等。这些因素除了当时北方环境提供了某种可能的存在外,从地名、稻作技术和鱼类分布等方面都显示出某种南方因素的介入与存在。本文从物产和技术入手,揭示其中的南方农业因素,探讨其进入北方的途径,包括人员往来和文本传播,藉以展示前此相关研究未曾注意的一面,即中国南、北方农业文化交流与技术传播。

  • Subsurface irrigation with ceramic emitters improves wolfberry yield and economic benefits on the Tibetan Plateau, China

    分类: 农、林、牧、渔 >> 农业基础学科 提交时间: 2023-11-13 合作期刊: 《干旱区科学》

    摘要: Climate warming has led to the expansion of arable land at high altitudes, but it has also increased the demand for water use efficiency (WUE). To address this issue, the development of water-saving irrigation technology has become crucial in improving water productivity and economic returns. This study aimed to assess the impacts of three irrigation methods on water productivity and economic returns in wolfberry (Lycium barbarum L.) cultivation on the Tibetan Plateau, China during a two-year field trial. Results showed that subsurface irrigation with ceramic emitters (SICE) outperformed surface drip irrigation (DI) and subsurface drip irrigation (SDI) in terms of wolfberry yield. Over the two-year period, the average yield with SICE increased by 8.0% and 2.3% compared with DI and SDI, respectively. This improvement can be attributed to the stable soil moisture and higher temperature accumulation achieved with SICE. Furthermore, SICE exhibited higher WUE, with 14.6% and 4.5% increases compared with DI and SDI, respectively. In addition to the agronomic benefits, SICE also proved advantageous in terms of economic returns. Total average annual input costs of SICE were lower than the other two methods starting from the 8th year. Moreover, the benefit-cost ratio of SICE surpassed the other methods in the 4th year and continued to widen the gap with subsequent year. These findings highlight SICE as an economically viable water-saving irrigation strategy for wolfberry cultivation on the Tibetan Plateau. Thus, this research not only provides an effective water-saving irrigation strategy for wolfberry cultivation but also offers insights into addressing irrigation-related energy challenges in other crop production systems.
     

  • Nitrogen application levels based on critical nitrogen absorption regulate processing tomatoes productivity, nitrogen uptake, nitrate distributions, and root growth in Xinjiang, China

    分类: 农、林、牧、渔 >> 农业基础学科 提交时间: 2023-10-17 合作期刊: 《干旱区科学》

    摘要: The unreasonable nitrogen (N) supply and low productivity are the main factors restricting the sustainable development of processing tomatoes. In addition, the mechanism by which the N application strategy affects root growth and nitrate distributions in processing tomatoes remains unclear. In this study, we applied four N application levels to a field (including 0 (N0), 200 (N200), 300 (N300), and 400 (N400) kg/hm2) based on the critical N absorption ratio at each growth stage (planting stage to flowering stage: 22%; fruit setting stage: 24%; red ripening stage: 45%; and maturity stage: 9%). The results indicated that N300 treatment significantly improved the aboveground dry matter (DM), yield, N uptake, and nitrogen use efficiency (NUE), while N400 treatment increased nitrate nitrogen (NO3–-N) residue in the 20–60 cm soil layer. Temporal variations of total root dry weight (TRDW) and total root length (TRL) showed a single-peak curve. Overall, N300 treatment improved the secondary root parameter of TRDW, while N400 treatment improved the secondary root parameter of TRL. The grey correlation coefficients indicated that root dry weight density (RDWD) in the surface soil (0–20 cm) had the strongest relationship with yield, whereas root length density (RLD) in the middle soil (20–40 cm) had a strong relationship with yield. The path model indicated that N uptake is a crucial factor affecting aboveground DM, TRDW, and yield. The above results indicate that N application levels based on critical N absorption improve the production of processing tomatoes by regulating N uptake and root distribution. Furthermore, the results of this study provide a theoretical basis for precise N management.
     

  • Leguminosae plants play a key role in affecting soil physical-chemical and biological properties during grassland succession after farmland abandonment in the Loess Plateau, China

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2023-10-17 合作期刊: 《干旱区科学》

    摘要: Leguminosae are an important part of terrestrial ecosystems and play a key role in promoting soil nutrient cycling and improving soil properties. However, plant composition and species diversity change rapidly during the process of succession, the effect of leguminosae on soil physical-chemical and biological properties is still unclear. This study investigated the changes in the composition of plant community, vegetation characteristics, soil physical-chemical properties, and soil biological properties on five former farmlands in China, which had been abandoned for 0, 5, 10, 18, and 30 a. Results showed that, with successional time, plant community developed from annual plants to perennial plants, the importance of Leguminosae and Asteraceae significantly increased and decreased, respectively, and the importance of grass increased and then decreased, having a maximum value after 5 a of abandonment. Plant diversity indices increased with successional time, and vegetation coverage and above- and below-ground biomass increased significantly with successional time after 5 a of abandonment. Compared with farmland, 30 a of abandonment significantly increased soil nutrient content, but total and available phosphorus decreased with successional time. Changes in plant community composition and vegetation characteristics not only change soil properties and improve soil physical-chemical properties, but also regulate soil biological activity, thus affecting soil nutrient cycling. Among these, Leguminosae have the greatest influence on soil properties, and their importance values and community composition are significantly correlated with soil properties. Therefore, this research provides more scientific guidance for selecting plant species to stabilize soil ecosystem of farmland to grassland in the Loess Plateau, China.
     

  • Combination of artificial zeolite and microbial fertilizer to improve mining soils in an arid area of Inner Mongolia, China

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2023-10-17 合作期刊: 《干旱区科学》

    摘要: Restoration of mining soils is important to the vegetation and environment. This study aimed to explore the variations in soil nutrient contents, microbial abundance, and biomass under different gradients of substrate amendments in mining soils to select effective measures. Soil samples were collected from the Bayan Obo mining region in Inner Mongolia Autonomous Region, China. Contents of soil organic matter (SOM), available nitrogen (AN), available phosphorus (AP), available potassium (AK), microbial biomass carbon/microbial biomass nitrogen (MBC/MBN) ratio, biomass, and bacteria, fungi, and actinomycetes abundance were assessed in Agropyron cristatum L. Gaertn., Elymus dahuricus Turcz., and Medicago sativa L. soils with artificial zeolite (AZ) and microbial fertilizer (MF) applied at T0 (0 g/kg), T1 (5 g/kg), T2 (10 g/kg), and T3 (20 g/kg). Redundancy analysis (RDA) and technique for order preference by similarity to ideal solution (TOPSIS) were used to identify the main factors controlling the variation of biomass. Results showed that chemical indices and microbial content of restored soils were far greater than those of control. The application of AZ significantly increases SOM, AN, and AP by 20.27%, 23.61%, and 40.43%, respectively. AZ significantly increased bacteria, fungi, and actinomycetes abundance by 0.63, 3.12, and 1.93 times of control, respectively. RDA indicated that AN, MBC/MBN ratio, and SOM were dominant predictors for biomass across samples with AZ application, explaining 87.6% of the biomass variance. SOM, MBC/MBN ratio, and AK were dominant predictors with MF application, explaining 82.9% of the biomass variance. TOPSIS indicated that T2 was the best dosage and the three plant species could all be used to repair mining soils. AZ and MF application at T2 concentration in the mining soils with M. sativa was found to be the most appropriate measure.
     

  • 科研合作中的核心合作者的界定与测算——一种基于H指数的测算方式

    分类: 农、林、牧、渔 >> 农、林、牧、渔业科学其他学科 提交时间: 2023-09-05 合作期刊: 《农业图书情报学报》

    摘要: 目的/ 意义 不同合作者在科研合作中扮演不同角色,承担相应职责。区分科研合作对象中的不同角色,对于科研人才评价和人力资源配置具有重要意义。本文基于 H 指数的测算方式,使用合作次数来识别科学家合作关系中的核心合作者。 方法/ 过程 以中国与G7 国家计算机领域高产科学家为研究对象。首先,识别出核心合作者并分析其规模与占比。其次,基于 H 指数拟合公式提出核心合作者人数的估算公式。最后,利用该式比较理论值与实际值的差异。 结果 / 结论 研究发现,在核心合作者的规模与占比上,各国核心合作者人数普遍为 3 耀7 人,且比例均不超过 10%。核心合作者人数可使用发文量与 篇均合作者人数的幂次方乘积来估算,美国、德国和英国的核心合作者占比更低,人才的流动和交流较为频繁,而意大利、日本和中国的核心合作者人数占比偏高,表明人才流动性不足,科研合作相对固化。

  • 金黄散贴敷疗法治疗1例痛风性关节炎急性发作患者的护理体会

    分类: 农、林、牧、渔 >> 畜牧、兽医科学 分类: 医学、药学 >> 军事医学与特种医学 提交时间: 2023-08-28

    摘要: 本文总结1例痛风性关节炎急性发作患者行金黄散贴敷疗法的护理体会。基于中医辨证,通过采用金黄散外用贴敷治疗,结合健康教育、饮食指导等综合护理干预,使患者达到疼痛缓解的效果。

  • 河套灌区不同配置农田防护林对田间土壤水分和养分储量的影响

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2023-08-26 合作期刊: 《干旱区研究》

    摘要: 农田防护林作为提高生态环境效益的有效农业管理方式,对改善土壤理化性质、改善生态环境,提高作物产量具有重要意义。在河套灌区选择三种典型农田防护林(4行林带、5行林带和8行林带)测量了2019—2021年生长季农田内距防护林0.3 H、0.7 H、1 H、2 H、3 H和4 H处0~100 cm的土壤性质和防护林与农田的植被属性,测算了土壤水分储量(SMS)和土壤养分储量[碳储量(SCS)、氮储量(SNS)和磷储量(SPS)]。结果表明:(1)不同防护林系统水平方向上的土壤容重和土壤黏粒含量差异显著,在垂直方向上土壤属性均有显著差异。(2)防护林具有较好的保水性和养分供应功能,其中4行林带的土壤水分储量和养分储量高于其他林带,分别为SMS 237.44 mm、SCS 544.93 g·m-2、SNS 953.72 g·m-2和SPS 859.04 g·m-2。(3)4行林带的整体长势比较好,其平均树高为30.06 m,胸径为0.41 m,且4行防护林的作物产量最高,为15.75 t·hm-2。(4)冗余分析结果显示,不同防护林系统中,环境因子与生态系统功能之间存在密切关系,土壤特性与土壤水分和养分储量关系密切,另外,植被属性与SNS和SPS基本呈负相关。综上所述,4行林带的水分养分供给能力最强,本研究结果可为生态脆弱地区的防护林建设和生态修复提供有效的理论依据。

  • 基于随机森林算法的土壤含盐量预测

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2023-08-26 合作期刊: 《干旱区研究》

    摘要: 快速监测区域土壤盐渍化信息,对于盐渍化治理与生态环境保护具有重要意义。本文以Sentinel-2A和Landsat8 OLI遥感影像为数据源,以银川平原为研究区,利用谷歌地球引擎(Google Earth Engine,GEE)平台,基于随机森林算法,通过建立光谱指数特征与地面实测土壤含盐量之间的关系,进行土壤含盐量估算。结果表明:GEE能够为土壤含盐量预测提供可靠的数据支撑;以Sentinel-2A为数据源建立的随机森林模型具有更好的预测精度(R2=0.789,RMSE=1.487),优于Landsat8 OLI,可用于土壤含盐量高分辨率遥感估算,能够为大尺度土壤含盐量监测工作提供理论支撑。

  • 洪水漫溢对塔里木河中游河岸胡杨林土壤有机碳及活性组分的影响

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2023-08-26 合作期刊: 《干旱区研究》

    摘要: 塔里木河生态输水使流域两岸洪水漫溢强度增加,进而对河岸胡杨林生态系统碳循环产生了重要影响。以塔里木河中游周期性洪水漫溢区胡杨林为研究对象,测定并分析河岸胡杨林洪水漫溢过程中漫溢前(W1)、漫溢第4 d(W2)、漫溢第17 d(W3)和退水后(W4)4个不同阶段1 m土体有机碳及活性组分含量的变化特征。结果表明:(1)SOC(土壤有机碳)含量在漫溢前均高于漫溢后;洪水漫溢对0~20 cm土层SOC含量的影响较20~100 cm土层显著;在同一阶段内,随着土层的深入,SOC含量呈降低趋势。(2)0~10 cm及40~100 cm土层的土壤DOC(可溶性有机碳)、MBC(微生物生物量碳)含量在漫溢第4 d较漫溢前均显著升高,但随着漫溢时间的延长,其含量逐渐降低,且各阶段间差异显著(P<0.05);同一土层随漫溢时间的延长DOC/SOC、MBC/SOC差异显著(P<0.05)。(3)漫溢前0~10cm土层EOC(易氧化有机碳)含量高于漫溢后,其他土层EOC含量则表现为漫溢期高于漫溢前及退水后;0~10 cm、20~60 cm土层EOC/SOC在不同漫溢阶段间差异显著(P<0.05)。(4)漫溢前至漫溢第17 d SOC与DOC含量呈极显著正相关(r>0.69,n=15),退水后EOC和DOC呈显著正相关(r=0.54,n=15),漫溢前SOC和DOC含量与漫溢后各阶段含量之间相关性显著。综上所述,塔里木河中游洪水漫溢过程对河岸胡杨林SOC及活性组分分布产生了显著影响,并且各组分的敏感土层不同,SOC以0~20 cm土层影响最为显著,DOC、MBC以0~10 cm及40~100 cm土层影响最为显著,EOC则为20~60 cm土层影响最为显著,其变化规律具有森林和湿地的双重特征。

  • 蒸散分离的玉米水分利用效率变化及影响因素

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2023-08-25 合作期刊: 《干旱区研究》

    摘要: 水分利用效率(WUE)是农田生态系统碳水循环的重要指标,对指导农业灌溉和提高水分生产力有重要意义。宁夏灌区是我国地处干旱气候带的大型灌区,其中,玉米种植面积最大。在涡度通量观测农田生态系统实际蒸散发(ET)的基础上,利用氢氧稳定同位素法将蒸散发分割为土壤蒸发(evaporation,E)、植物蒸腾(transpiration,T),并通过光能利用模型估算宁夏引黄灌区典型玉米农田生态系统的总初级生产力(GPP),计算群体水分利用效率WUET=GPP/T、生态系统水分利用效率WUEET=GPP/ET 以及固有水分利用效率(Intrinsic Water Use Efficiency)IWUEVPD=(GPP·VPD)/ET三种水分利用效率,进而从函数响应关系、相关性以及敏感性三个方面分析不同水分利用效率与气温、饱和水汽压差(VPD)、CO2浓度、光合有效辐射以及土壤含水量等环境因子之间的关系。结果表明:宁夏引黄灌区玉米农田生态系统生长季的实际蒸散发变化呈单驼峰型,作物蒸腾与实际蒸散发的变化趋势相一致。WUET在生育期内呈“W型”变化,WUEET与IWUEVPD在生育期内呈“单峰型”变化,三种WUE的峰值出现在抽雄期,分别达到5.90 kg C·m-3·H2O、5.02 kg C·m-3·H2O和32.90 kg C·hPa·m-3·H2O,灌浆后期三种水分利用效率开始降低,玉米成熟晚期由于蒸腾微弱所以WUET略有增加。WUET、WUEET和IWUEVPD与土壤含水量显著正相关,相关度和敏感性最强;VPD与三种WUE显著负相关,相关度和敏感性最强次之;气温、光合有效辐射以及CO2浓度与三种WUE的负相关性但不是敏感因素。因此,在宁夏引黄灌区土壤水分和VPD是影响玉米农田生态系统WUE的关键因素。

  • 毛乌素沙地不同林龄杨柴灌木林土壤呼吸及其影响因素

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2023-08-25 合作期刊: 《干旱区研究》

    摘要: 为探究沙漠化逆转过程中林地土壤呼吸速率和通量变化趋势及其主要影响因子,本文选择毛乌素沙地林龄为9 a、18 a和30 a杨柴人工灌木林和未造林流动沙地(CK),用Li-8100A土壤碳通量监测系统对土壤呼吸速率进行定位观测,并对主要环境影响因子进行了测定。结果表明:(1)土壤呼吸速率和通量均在植物生长季5—10月呈现出先升高后降低的单峰曲线变化规律,最高值出现在7月。(2)土壤呼吸速率和通量随杨柴林龄增长呈持续增加趋势,而呼吸速率温度敏感性(Q10)则呈持续下降趋势。生长季5—10月杨柴林各样地土壤呼吸平均速率大小为:30 a(2.16 μmol·m-2·s-1)>18 a(1.98 μmol·m-2·s-1)>9 a(1.41 μmol·m-2·s-1)>CK(0.24 μmol·m-2·s-1);土壤呼吸碳通量值大小顺序为:30 a(365.74 g C·m-2)>18 a(313.63 g C·m-2)>9 a(218.66 g C·m-2)>CK(40.08 g C·m-2)。(3)CK、9 a和18 a样地土壤呼吸速率季节性变化主要受土壤温度和水分的耦合作用(P<0.01),而30 a样地的主控因子为土壤温度(P<0.01)。(4)土壤呼吸碳通量与植被生物量、土壤有机碳和全氮含量均呈显著正相关关系(P<0.05)。

  • 阿拉善高原土地砾化特征及监测指标

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2023-08-25 合作期刊: 《干旱区研究》

    摘要: 探究阿拉善高原土地砾化地区的地表砾石覆盖度(Gc),单位面积地表砾石质量(Gm),0~5 cm、5~10 cm土层深度的砾石质量含量[Gmc(0~5 cm)、Gmc(5~10 cm)]特征及其相关关系,为其砾化土地的监测与评估奠定指标基础。野外采集阿拉善高原土地砾化地区的砾石样品,测定其Gc、Gm、Gmc(0~5 cm)和Gmc(5~10 cm)。通过单因素方差分析、邓肯多重比较、一元线性回归和相关性分析,探究阿拉善高原的土地砾化特征。结果表明:(1)阿拉善高原各样地总的Gc(Gm)的平均值为39.49%(3544.04 g·m-2)。(2)粒径为4~8 mm和8~16 mm的Gc(Gm)要显著高于其他粒径的Gc(Gm)(P<0.05),且粒径为4~8 mm的Gc(Gm)变异系数最小,最为稳定。(3)阿拉善高原各样地在空间分布格局上呈现出Gc和Gm由东向西、由南向北逐渐增大的分布规律。(4)不同粒径(总)的Gm和Gc均呈极显著的一元线性回归关系(P<0.01),Gm也可以很好的评价土地砾化程度。并根据Gc的砾化程度分级阈值确定了相应的Gm的砾化程度分级阈值。(5)除2~4 mm和>32 mm的粒径外,其他粒径的Gc、Gm与0~5 cm土层内Gmc的相关性要明显大于与5~10 cm土层内Gmc的相关性,总的Gc、Gm与0~5 cm土层内Gmc的相关性要明显大于与5~10 cm土层内Gmc的相关性。(6)确定了砾化土地类型之一的戈壁地表砾石覆盖度阈值为25%。研究结果可为阿拉善高原和其他区域砾化土地的监测和评估奠定指标基础。
     

  • 降雨频率对甘南尕海湿草甸土壤碳氮磷化学计量特征的影响

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2023-08-25 合作期刊: 《干旱区研究》

    摘要: 降雨是湿地水资源补给量和土壤呼吸的重要扰动因子,全球气候变化导致的未来极端降雨变率增大对湿地生态系统有着重要影响。为探究极端降雨频率下青藏高原湿草甸土壤有机碳(SOC)、全氮(TN)、全磷(TP)含量及化学计量比的变化特征,本文以青藏高原东北边缘碌曲县尕海-则岔自然保护区境内的湿草甸土壤为研究对象,设置空白对照(CK:0 mm)、每周浇灌一次(DF1:25 mm×19次)、每两周浇灌一次(DF2:25 mm×9次)、每三周浇灌一次(DF3:25 mm×6次)和每四周浇灌一次(DF4:25 mm×4次)5种处理,分析极端降雨频率下0~40 cm土层土壤SOC、TN和TP化学计量特征的变化规律。结果表明:在不同降雨频率下,土壤SOC含量随降雨频率增加而增加,TN和TP含量则与之相反。在土壤垂直剖面上,SOC和TN含量均随土层深度增加而降低,TP含量随土层深度增加无显著变化;C:P和N:P均随土层加深有所降低,而C:N随土层加深无显著变化;C:N、C:P和N:P在不同降雨频率间差异不显著;此外,随着时间的推进,土壤SOC含量在生长季不同月份呈现先增后减的变化趋势,TN含量则呈现先减后增的变化趋势,而TP含量呈“M”型变化趋势。因此,随着全球降雨格局变化程度持续增加,较高的降雨频率会加剧高寒湿草甸浅层土壤氮磷含量的流失,造成高寒湿草甸水环境富营养化的危害加剧。
     

  • 呼伦贝尔沙地樟子松人工林土壤细菌网络特征

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2023-08-25 合作期刊: 《干旱区研究》

    摘要: 为揭示呼伦贝尔沙地樟子松人工林土壤细菌相互关系,以呼伦贝尔沙地不同林龄樟子松人工林(25 a、34a和43 a)为研究对象,以沙质草地为对照,采用分子生态网络分析法对不同土层(0~10 cm和10~20 cm)土壤细菌群落进行比较分析。结果表明:(1)从25 a到43 a,土壤细菌网络总边数增多,平均路径长度降低。土壤深度由0~10cm到10~20 cm,人工林土壤细菌网络总边数减少,平均路径长度升高。与沙质草地相比,人工林土壤细菌网络总边数较少。(2)25 a人工林关键菌种隶属于嗜酸菌目(Acidimicrobiales)、RB41 和MB-A2-108,34 a人工林关键菌种隶属于Gaiellales,43 a人工林关键菌种隶属于Gaiellales、RB41、Subgroup_7、Subgroup_6、和DA101_soil_group,草地关键菌种隶属于匿杆菌门(Latescibacteria)。(3)全氮、氨氮、微生物碳含量和脲酶酶活性对土壤细菌网络中具有高中介中心性的部分细菌有显著正相关影响(P<0.05);转化酶和过氧化氢酶活性、土壤含水量以及速效磷含量对土壤细菌网络中具有高中介中心性的部分细菌有显著负相关影响(P<0.05);土壤有机质对土壤细菌网络中具有高中介中心性的部分细菌既有显著正相关影响又有显著负相关影响(P<0.05)。樟子松人工林从25 a到43 a,土壤细菌网络愈加复杂和紧密,土壤深度由0~10 cm到10~20 cm,网络复杂性和紧密度降低;与草地相比,人工林土壤细菌网络复杂性较低。43 a人工林土壤细菌网络关键菌种类型数量最多。另外,土壤细菌网络受土壤有机质影响最大。研究结果有助于深入理解呼伦贝尔沙地樟子松人工林土壤细菌群落,并为呼伦贝尔沙地樟子松人工林的可持续经营提供科技支撑。

  • 基于人工智能的地球物理参数反演范式理论及判定条件

    分类: 农、林、牧、渔 >> 农业基础学科 提交时间: 2023-08-14 合作期刊: 《智慧农业(中英文)》

    摘要: [目的/意义]人工智能(Artificial Intelligence,AI)技术已在学术和工程应用领域掀起了研究高潮,在 地球物理参数和农业气象遥感参数反演方面也表现出了强大的应用潜力。目前大部分AI技术在地学和农学的应用 还是“黑箱”,没有物理意义或缺乏可解释性及通用性。为了促进AI在地学和农学的应用和培养交叉学科的人才, 本研究提出基于AI耦合物理和统计方法的地球物理参数反演范式理论。[方法]首先基于物理能量平衡方程进行 物理逻辑推理,从理论上构造反演方程组,然后基于物理推导构建泛化的统计方法。通过物理模型模拟获得物理 方法的代表性解以及利用多源数据获得统计方法代表性的解作为深度学习的训练和测试数据库,最后利用深度学 习进行优化求解。[结果和讨论] 判定形成具有通用性和物理可解释的范式条件包括:(1) 输入与输出变量(参 数) 之间必须存在因果关系;(2) 输入和输出变量(参数) 之间理论上可以构建闭合的方程组(未知数个数少于 或等于方程组个数),也就是说输出参数可以被输入参数唯一确定。如果输入参数(变量) 和输出参数(变量) 之 间存在很强的因果关系,则可以直接使用深度学习进行反演。如果输入参数和输出参数之间存在弱相关性,则需 要添加先验知识来提高输出参数的反演精度。此外,本研究以农业气象遥感中的关键参数地表温度、发射率、近 地表空气温度和大气水汽含量联合反演作为案例对理论进行了证明,分析结果表明本理论是可行的,并且可以辅 助优化设计卫星传感器波段组合。[结论] 本理论和判定条件的提出在地球物理参数反演史上具有里程碑意义。