Effect of free-air CO_2 enrichment on nematode communities in a Chinese farmland ecosystem

At a rice wheat rotational free air CO 2 enrichment(FACE) platform, the effect of elevated atmospheric CO 2 on soil nematode communities in a farmland ecosystem was studied. Wheat plots were exposed to elevated atmospheric CO 2(ambient 370 μl/L + 200 μl/L). 32 families and 40 genera of nematode were observed in soil suspensions during the study period. Under FACE treatment, the numbers of total nematodes, bacterivores and fungivores exhibited an increasing trend. Because of the seasonal variation of soil temperature and moisture, the effect of elevated atmospheric CO 2 on soil nematodes was only observed under favorable conditions. The response of nematode communities to elevated atmospheric CO 2 may indicate the change of soil food web.

Response of N_2O Emissions of Farmland Ecosystem on Temperature Rising

[Objective] The aim was to study on response of N2O emissions of farm- land ecosystem on temperature rising. [Methed] In farmland ecosystem in Huaibei City in Anhui Province, N2O emission by twelve varieties of crop on temperature was researched with DeNitrification-DeComposition （NDC）. [Result] Response of dry- land crop on temperature rising can be divided into three categories, as follows： The first category, N2O emission of crop changed little during the temperature increasing, for example, from 0 to 3 %;, the emissions by potatoes, cotton, maize and rapeseed increased little and decreased little when temperature changed from 1.5 to 3 ℃. Crops of the second category declined with temperature increasing in N2O emission, for example, N2O emission decreased by 8.1% with temperature increasing from 0 to 3 ℃, including sugar cane, tobacco, wheat, soybean and pea. In third category, N2O emission of crop grew with temperature increasing, for example, the emission of rice, vegetables and fruit trees increased by 22.8% when the temperature grew from 0 to 3 ℃. [Conclusion] The research indicated that N2O emission in ecosystem of drv farmland increased little with temoerature risina.

The Dynamics and Driving Force of Farmland Ecosystem Productivity

Based on the experimental data of crop yield, soil water and fertility of a dryland farming ecosystem in northwest China, asystematic analysis is carried out to study the dynamics of dryland farming ecosystem productivity and its limitingfactors. This paper also discusses which of the two limiting factors, i.e., soil water or fertility, is the primary factor and theirdynamics. The result shows that fertility is the primary limiting factor when the productivity is rather low. As chemicalfertilizer input increases and the productivity promotes, water gradually becomes the primary limiting factor. Chemicalfertilizers and plastic film mulching are the two major driving forces that determine the crop productivity and its stabilityin these areas.

The Status of Ammonia(NH_3) Emissions and Achievements of Emissions Reduction Technology in Farmland Ecosystems

NH3 is one of the leading causes of grey haze, and one of the main causes of serious ecological imbalances that result in environmental problems such as acid rain and air quality deterioration. At present, excessive fertilizer application greatly intensifies NH3 emissions intensity on farmland. In order to understand status and achievements of research on farmland NH3 emissions, the literature of farmland NH3 emission-related studies was retrieved from SCl journals and the Chinese science citation database. These are summarized with respect to the research progress on NH3 emission factors and emission reduction technologies. The future research direction of field NH3 emission and emission reduction technology need to strengthen the field observation on different soil environment and crop types, and understand the effect of NH3 emission on fertilizer application period and the proportion, temperature and organic fertilizer management in farmland mainly. The research results can provide more information about the factors that influence NH3 emissions. This study offers theoretical guidance and support directed at mitigating farmland NH3 emissions in the future.

Evaluation of Loss of Degraded Farmland Ecosystem Services in Tibet, China

Four environmemtal service functions of wheat, barley and rape ecosystem are evaluated in material production, air adjustment (including carbon dioxide fixation and oxygen release in Tibetan Autonomous Region), water conservation, and nutrient recycling. Based on it the economic loss of environment due to desertification is valued. The results show that the service functions of farmland ecosystem in Tibet are totally valued at 4 436. 2 × 106 yuan, the value of each service function is ordered as: air adjustment 2 070.2× 106 yuan (46.67%), material production 2 011. 1× 106 yuan (45.33%), nutrient recycling 193. 1×106 yuan (4.35%), and water conservation 161. 8×106 yuan (3.65%). The total area of wheat, barley and rape in Tibet is over 189 700 ha, and the service function of farmland ecosystem is valued at 23 386 yuan/ha per year. The degraded area of arable land in Tibet is about 1 082 ha per year, equivalent to the annual loss of farmland ecosystem service value of 25.3×106 yuan. Over the past 30 years the total loss of the value is 1 347.0×106 yuan.

Effects of nitrogen and phosphorus additions on soil microbial community structure and ecological processes in the farmland of Chinese Loess Plateau

Microorganisms regulate the responses of terrestrial ecosystems to anthropogenic nutrient inputs.The escalation of anthropogenic activities has resulted in a rise in the primary terrestrial constraining elements,namely nitrogen(N)and phosphorus(P).Nevertheless,the specific mechanisms governing the influence of soil microbial community structure and ecological processes in ecologically vulnerable and delicate semi-arid loess agroecosystems remain inadequately understood.Therefore,we explored the effects of different N and P additions on soil microbial community structure and its associated ecological processes in the farmland of Chinese Loess Plateau based on a 36-a long-term experiment.Nine fertilization treatments with complete interactions of high,medium,and low N and P gradients were set up.Soil physical and chemical properties,along with the microbial community structure were measured in this study.Additionally,relevant ecological processes such as microbial biomass,respiration,N mineralization,and enzyme activity were quantified.To elucidate the relationships between these variables,we examined correlation-mediated processes using statistical techniques,including redundancy analysis(RDA)and structural equation modeling(SEM).The results showed that the addition of N alone had a detrimental effect on soil microbial biomass,mineralized N accumulation,andβ-1,4-glucosidase activity.Conversely,the addition of P exhibited an opposing effect,leading to positive influences on these soil parameters.The interactive addition of N and P significantly changed the microbial community structure,increasing microbial activity(microbial biomass and soil respiration),but decreasing the accumulation of mineralized N.Among them,N24P12 treatment showed the greatest increase in the soil nutrient content and respiration.N12P12 treatment increased the overall enzyme activity and total phospholipid fatty acid(PLFA)content by 70.93%.N and P nutrient contents of the soil dominate the microbial community structure and the corresponding changes in hydrolytic enzymes.Soil microbial biomass,respiration,and overall enzyme activity are driven by mineralized N.Our study provides a theoretical basis for exploring energy conversion processes of soil microbial community and environmental sustainability under long-term N and P additions in semi-arid loess areas.

基于水文气象因子的农田生态系统碳通量预测

以黄河流域下游禹城农田生态系统为研究对象,采用中国通量观测研究网络(ChinaFLUX)禹城站通量塔观测的碳水通量和水文气象数据,基于特征重要性方法确定影响农田生态系统CO_(2)交换量的主控环境因子。基于所有环境因子和主控环境因子分别构建碳通量预测的机器学习模型,采用均方误差(MSE)、平均绝对误差(MAE)和决定系数(R~2)评估测试集的模型预测性能。结果表明,影响禹城农田生态系统碳通量的主控环境因子为净辐射、土壤温度、饱和水汽压亏缺、土壤含水量。与单一模型相比,集成模型具有更好的预测性能。单一模型中,MLPRegressor模型预测性能较好,R~2为0.830,MSE为3.113,MAE为1.283。集成模型中,XGBRegressor模型预测性能较好,R~2为0.845,MSE为2.838,MAE为1.149。采用主控环境因子与采用全部环境因子构建的机器学习模型具有相似预测性能。

耕地生态补偿问题研究进展:运行机制与政策实践

耕地生态系统是全球最重要的生态系统之一。耕地生态补偿作为调节耕地保护相关者利益关系的公共制度安排,在保护耕地生态系统、促进耕地可持续利用、保障粮食安全方面具有重要作用。论文从耕地生态补偿的概念与内涵、补偿机制构建、补偿实践探索三个方面对相关文献进行梳理,认为现有研究存在耕地完全价值体现不充分、补偿标准与补偿年限判定不明确、补偿资金来源不丰富、补偿主体利益分配不清晰的突出问题,并在此基础上提出以法制化、多元化、市场化、信息化为核心的未来研究方向。

退耕还林地生态环境损害评估案例分析及应用

近年来,随着我国经济的高速发展,林地生态环境损害事件日益增加。不同类型的生态系统或同一生态系统在不同区域所提供的生态服务功能侧重均不同,鉴定评估林地生态系统的环境损害价值时应选用不同的测算方法。通过阐述理论公式法和实际监测法的原理和适用范围及其在生态环境损害评估中的应用,并对量化过程中参数的选取原则与方法进行说明。结合案例分析非法占用退耕还林地导致的生态环境损害范围和程度,计算出2012年~2019年的生态环境损害价值量为205万元。研究退耕还林地生态环境损害典型案例,并将其推广应用于小规模普通林地,对林地生态环境损害案件的鉴定评估环节具有重要引领作用。

中国省域农田生态系统碳足迹时空演变分析

以2001—2020年中国31个省域主要农田投入、产出及耕地面积等有关统计资料为基础,对中国农田生态系统的碳吸收、碳排放和碳足迹进行核算,并分析其时序和空间格局演变特点。结果表明:(1)从时间上看,农田生态系统碳吸收总量呈波动上升态势,其中农作物碳吸收能力最强的是玉米;农田生态系统碳排放总体呈上升趋势,增长幅度为11.10%,化肥在主要碳排放途径中占比最高,达到了56.26%;农田生态系统碳足迹由2001年的16.37×10^(6)hm^(2)下降到2020年的13.41×10^(6)hm^(2),整体呈现出碳生态盈余。(2)从空间上看,中国31个省域的农田生态系统碳足迹在总量上存在明显差异,呈现出东部和北部高、西部低的分布格局,且海南和西藏等呈大幅度增长趋势,天津和上海等呈下降趋势;受耕地面积和农作物播种面积的影响,单位面积碳足迹整体呈先增长后下降的趋势且各省域之间呈现出显著差异,其中单位面积碳足迹最大的北京和最小的广西之间相差0.35 hm^(2)/hm^(2)。

农田生态系统碳源/汇时空演变因素分析——以黑龙江省为例

文章基于黑龙江省农资投入、农作物播种面积等数据,采用LMDI分解模型,对2008—2021年该省农田生态系统碳源/汇量进行测算。结果表明:①黑龙江省农田生态系统碳排放量呈快速增长后缓慢下降的态势,其中稻田种植产生的CH4导致碳排放量占比最高,为59.66%;碳吸收量总体呈上升态势,年均增长率为3.85%,其中玉米和水稻增幅较大。②从空间变化来看,单位播种面积碳排放量呈中东部高于其他地区的分布格局,单位播种面积碳吸收量呈东部、南部、西部高于北部的分布格局。③对碳源/汇影响因素进行分析可知,提升农业生态效率、优化农业生产结构、控制劳动力规模可有效降低碳排放;碳汇系数、碳汇技术水平对碳吸收量有促进作用,未来可强化精准管理、提升智能化农业效率,增强碳汇能力。

2006-2022年中国科学院环江喀斯特生态系统观测站农田长期观测样地土壤养分数据集

中国科学院环江喀斯特生态系统观测研究站(本文中简称“环江站”)是我国西南喀斯特地区重要的农业生态系统长期野外定位观测研究站,是依照中国生态系统研究网络(Chinese Ecosystem Research Network,简称CERN)联网监测规范布置的试验样地。自2005年以来,环江站依照国家生态系统观测研究网络(National Ecosystem Research Network of China,简称CNERN)和CERN农田生态系统观测指标要求,逐一开展针对喀斯特峰丛洼地农田生态系统水分、土壤、生物、气象等环境要素的监测活动。本数据集收集、整理了环江站2006–2022年8个长期联网监测样地的土壤养分数据,包括土壤有机质、全氮、全磷、全钾、碱解氮、有效磷、速效钾、缓效钾、pH值等9项指标,均进行了严格的数据质量控制与评估,并附有完整的样地背景信息和分析方法记录。本数据集反映了桂西北喀斯特峰丛洼地农业区传统代表性作物早晚稻、玉米、大豆、桑叶、柑橘等农作地土壤常规养分含量动态变化,对指导喀斯特峰丛洼地农业生产、培育土壤地力具有参考依据。

氮磷添加对黄土旱塬农田土壤线虫群落及能量结构的影响

为探究氮磷添加对黄土旱塬农田土壤线虫群落结构和微食物网中能量流动的影响,以中国科学院长武农业生态实验站长期施用氮磷肥农田土壤作为研究对象,选取6个处理,分别为:不施肥(CK),氮添加(N_(12)、N_(24)),磷添加(P_(12)、P_(24)),氮磷添加(N_(12)P_(12)),测定土壤理化性质,采用浅盘法分离线虫,分析线虫营养类群结构和生活史征,并计算线虫生态学指数,代谢足迹和食物网内部能量流动数值。结果表明:不同处理土壤的植物寄生线虫(Pp)比例显著高于其他类群(50.7%—66.4%),生活史为低营养级r策略者(cp2)的线虫类群比例也显著高于其他类群(68.1%—84.0%)。P_(12)处理的线虫丰度最高,为1147条/100 g干土,其次是P_(24)处理,为1100条/100 g干土。与CK相比,两种磷添加处理显著增加了香农多样性指数(H),提升了食真菌和捕食杂食线虫的代谢足迹,微食物网中拥有更高的能量通量,其余处理对线虫丰度和代谢足迹没有产生影响。与N_(24)处理相比,N_(12)处理显著增加了线虫群落的H,均匀度指数(J)和丰富度指数(SR)。N_(12)P_(12)处理增加了高营养级k策略者(cp4-5)的线虫数量,显著提高了结构指数(SI)。冗余分析表明,土壤中全磷和速效磷含量是影响线虫丰度和代谢足迹的主要环境因子。综上所述,适量氮添加提升了土壤线虫群落多样性和结构稳定性,过量氮添加会抵消这种积极影响。磷添加对线虫群落和代谢足迹产生积极影响并提高了土壤微食物网的能量通量,氮磷添加则为土壤线虫创造了适宜的生存环境。这一结果为黄土区农田土壤的施肥措施提供了科学依据。

秸秆覆盖还田保护性耕作对黄土旱塬土壤磷素组分的影响

为探究秸秆覆盖保护性耕作对黄土旱塬土壤磷素组分及碱性磷酸酶pho D基因的影响,本研究以陕西省咸阳市长武县境内的中国科学院长武黄土高原农业生态试验站为研究平台,设置无秸秆覆盖(CK)、每年7、8、9月高量秸秆覆盖(St_(90))、全生育期低量秸秆覆盖(S_(45))、全生育期高量秸秆覆盖(S_(90))4个处理,探讨不同秸秆覆盖模式下0~20 cm表层土壤基本理化性质、土壤磷素、有机磷组分、无机磷组分、碱性磷酸酶pho D基因拷贝数量特征及其影响机理。结果表明:相同覆盖时间下,全磷(TP)、速效磷(AP)、无机磷、Ca_(2)-P、中等活性有机磷(MLOP)含量均随着秸秆覆盖量的增加而显著增加;Ca_(10)-P是主要的无机磷组分,占比66.03%~72.34%,MLOP是主要的有机磷组分,占比70.70%~78.23%;秸秆覆盖使无机磷中的有效磷源Ca_(2)-P在无机磷中所占的比例显著增加,其他组分占比以及有机磷各组分占比并无显著变化。播种前后的短期覆盖相比于全年长期覆盖更有利于微生物的代谢,从而加快土壤有机磷的合成。不同秸秆覆盖处理土壤无机磷含量为985.33~1043.33 mg·kg^(-1),显著大于有机磷。冗余分析表明,土壤pH、全碳(TC)、有机碳(SOC)、含水率(SWC)与MLOP含量呈负相关关系,与高稳性有机磷(HSOP)呈正相关关系,Ca_(2)-P与SWC、SOC、pH、TP呈正相关关系,Ca_(10)-P与pH、NH_(4)^(+)-N呈正相关关系。秸秆覆盖可以提高碱性磷酸酶pho D基因拷贝数,但全生育期覆盖与高量秸秆覆盖的叠加作用,对碱性磷酸酶pho D基因有抑制作用。研究表明,秸秆覆盖可显著改变有机磷各组分含量,全生育期高量秸秆覆盖显著增加无机磷有效组分Ca_(2)-P含量,土壤有机磷与无机磷组分含量变化受土壤TC和pH的影响最大。

贺兰山东麓典型葡萄园土壤有机碳库组成及其活跃度

[目的]研究贺兰山东麓典型葡萄园土壤有机碳库的组成及其活跃度,量化该区域葡萄园生态系统潜在的固碳能力,为挖掘葡萄园碳汇能力和核算碳汇价值提供科学依据。[方法]以贺兰山东麓典型的新慧彬葡萄园为例,开展园区尺度的土壤有机碳取样调查与分析,研究土壤有机碳含量、密度和组分等特征。[结果](1)葡萄园0—100 cm剖面土壤有机碳平均含量为4.65 g/kg,土壤有机碳密度为64.5 t/hm^(2),虽然土壤有机质含量低,养分匮乏,但依然是葡萄园生态系统碳库的主要部分。(2)在垂直剖面上,土壤有机碳含量随着土层加深而递减,且0—40 cm表层和40—100 cm深层的土壤有机碳含量存在显著差异,表层土壤的有机碳富集系数大于1,对有机碳具有更强的固持能力。(3)土壤有机碳含量在园区范围内存在空间异质性,其中表层土壤有机碳的空间异质性受制于不同田块间葡萄品种及施肥等垦殖活动差异,而深层土壤有机碳的空间异质性主要受制于原始土壤的形成背景。(4)土壤有机碳活性、中性和惰性组分的比例约为1∶2∶5。惰性组分比例较高,碳库活度较低,稳定性较强。虽然惰性有机碳含量决定了总有机碳的高低,但中性有机碳含量的变化亦会影响总有机碳和全碳含量。[结论]贺兰山东麓葡萄园土壤碳库活度和有机碳含量水平较低。葡萄种植最终会增加土壤碳储量,增强生态系统的碳汇能力。

新疆农田和荒漠生态系统土壤有机碳储量及其影响因素

基于中国生态系统研究网络(CERN)长期监测数据,选取新疆维吾尔自治区代表暖温带干旱区的绿洲农田生态系统(阿克苏站)、代表暖温带荒漠区(策勒站)以及温带荒漠区(阜康站)的绿洲农田和荒漠生态系统综合观测场、辅助观测场和农户调查点2005—2020年0—100 cm土层的土壤有机碳(SOC)储量数据,分析新疆农田和荒漠生态系统SOC储量的影响因素。研究结果表明,2005—2020年0—100 cm土层SOC总储量平均值为阿克苏站(5.17 kg/m^(2))>阜康站(4.20 kg/m^(2))>策勒站(2.96 kg/m^(2))。0—20 cm、20—40 cm、40—60 cm土层的SOC分别约占0—100 cm土层储量的27.3%—35.3%、23.1%—24.6%和15.8%—17.5%。在阿克苏站,施肥量最高、灌溉量最低的农户调查点SOC储量最高;而在策勒站和阜康站,农户调查点和辅助观测场的施肥和灌溉措施分别最有利于提高SOC储量。总体来看,土壤含水量、地上生物量与SOC储量呈正相关关系;年平均气温与0—40 cm土层的SOC储量呈负相关关系。在单一生态站的生态系统尺度,年平均气温与SOC储量相关性不显著;地上生物量与策勒站和阜康站的SOC储量呈正相关关系,但是与阿克苏站0—40 cm土层的SOC储量呈负相关关系;施纯钾量与策勒站0—60 cm土层的SOC储量呈正相关关系,但与阜康站40—100 cm土层的SOC储量呈负相关关系。总之,与自然状态下的荒漠和农田不施肥相比,灌溉和施肥的农田管理措施有利于增加干旱区SOC储量。不同生态站要根据自身区域特点制定合理的农田管理模式,以维持较高的SOC储量。

不同频次氮素添加对大豆农田生态系统土壤线虫的影响

土壤线虫在维持陆地生态系统的稳定性、促进物质循环和能量流动方面起着重要作用。而氮肥的添加是影响农田土壤线虫的重要因素,农田施肥是增加农作物产量和提高经济效益的有效措施。然而以往研究大多关注氮肥添加量对土壤线虫的影响,对于氮添加频次对农田生态系统土壤线虫群落影响的认识不足。以农田生态系统大豆作物为研究对象,设置对照(C)、低频施氮(NL)和高频施氮(NH)3种处理,研究土壤线虫群落对不同频次氮添加的响应,分析不同频次氮添加对农田土壤线虫群落结构的影响及其机制,从而为农田生态系统管理提供基础数据和科学依据。结果表明:(1)施氮处理后,土壤线虫物种丰富度和密度无显著变化。在0~10 cm土层,低频施氮使食真菌线虫相对丰度显著提升197.33%,植食性线虫相对丰度显著降低64.51%;高频施氮使食细菌线虫相对丰度显著升高26.49%,植食性线虫相对丰度显著降低47.13%(P<0.05)。(2)在0~10 cm土层,低频施氮显著提高cp-1类群比例,并显著降低cp-3类群比例;高频施氮使cp-1类群比例显著升高(P<0.05)(cp-1表示cp值为1的线虫类群)。(3)低频施氮使0~10 cm土层线虫通道比值显著降低,>10~20 cm土层线虫群落基础指数显著升高,0~10和>10~20 cm土层线虫群落结构指数显著降低(P<0.05)。在0~10 cm土层,低频和高频施氮使线虫群落富集指数显著上升(P<0.05)。(4)冗余分析表明,铵态氮含量、含水率和硝态氮含量是驱动土壤线虫群落变化的主要环境因子。总的来说,施氮会改变土壤环境和线虫营养类群结构。施氮可使偏r对策者cp-1类群数量显著增加,加快土壤线虫类群的世代交替和能量流动,降低土壤生态群落稳定性。低频施氮显著降低线虫通道比值,这表明土壤分解路径中的真菌分解路径得到增强。

生物炭影响农田温室气体排放的研究进展

针对生物炭在农业生产中对温室气体排放的影响问题,论文综述了近几年有关生物炭对农田生态系统CO_(2)、CH_(4)和N_(2)O三种主要温室气体排放的影响研究,发现生物炭总体上可以减少温室气体的排放,但其实际效果受生物炭种类、土壤理化性质和微生物活性与丰度等多种因素的影响。为此,本文进一步总结了生物炭影响农田系统温室气体排放的作用机理。提出了三条可能机制:(1)生物炭疏松多孔,具有吸附性,依靠自身的吸附作用吸收土壤中的温室气体;(2)生物炭能改变土壤理化性质,使土壤疏松,团聚体和固体物含量提升,抑制土壤矿化,固碳能力提升,吸附性增强;(3)生物炭能改善土壤微生物的生存环境,提高土壤微生物的丰度和活性,微生物活动增强,可以更多地固定土壤中的氮,影响温室气体的排放。通过生物炭途径可助力农业碳减排。

福建省漳州市农田生态系统碳足迹年际变化

为准确估算漳州市农田生态系统碳足迹年际变化。本文基于2011-2020年漳州市农田生产投入、作物产量等数据,运用碳足迹分析方法计算农田生态系统的碳排放量、碳吸收量及碳足迹。结果表明:2011-2020年,碳排放总量呈现先增加后减少的特点;2015年碳吸收总量最大;粮食作物中碳吸收量大小依次为:水稻>甘薯>大豆>马铃薯>杂粮,非粮食作物中碳吸收量大小依次为:蔬菜>油菜籽>烟叶>芝麻;蔬菜对漳州市农田生态系统的碳吸收贡献最大;2015年碳足迹最小,2016年碳足迹最大,均小于同期耕地面积,实现碳生态盈余。建议漳州市科学合理地提高肥料利用率,推广低碳的环境友好型农业生产技术。

农田微塑料污染现状及对土壤生态系统的危害

微塑料由塑料分解而来,具有颗粒小、化学性质稳定、吸附性强等特点,广泛分布于环境中。农业中常见的农膜覆盖、肥料施用、农田灌溉等方式会造成大量的微塑料输入,且对土壤生态系统造成一定的影响和潜在威胁。为加深对农田土壤微塑料污染现状的了解,更好地防范其带来的生态风险,本研究综述了农田土壤微塑料的来源、污染现状、迁移和降解机制及对土壤生态系统的影响,在总结当前研究的基础上,为未来的土壤微塑料研究提供方向和思路。