Element Budgets in a Forested Watershed in Southern China: Estimation of a Proton Budget

We evaluated the element budgets in a forested watershed in Jiulianshan, southern China. The element input in bulk precipitation was characterized by high depositions of H⁺, NH₄ ⁺, Ca²⁺, and SO₄ ^2?, i.e., 400, 351, 299, and 876 eq/ha/yr, respectively. The outputs of H⁺, NH₄ ⁺, and SO₄ ^2? from the watershed were very low, while those of Ca²⁺ and Mg²⁺ were high, 712 and 960 eq/ha/yr, respectively. The element budgets suggested that i) the net retentions of H⁺, NH₄ ⁺, and SO₄ ^2? in this watershed were high, and ii) the net release of Mg²⁺ from this watershed was high mainly due to weathering. The net release of Ca²⁺ was not so high because of the high atmospheric deposition, while atmospheric deposition of Mg²⁺ was not so high (130 eq/ha/yr). Decrease of acid neutralizing capacity in the soil, i.e., net soil acidification, was caused mainly by the net release of Mg²⁺. Moreover, the net retention of SO₄ ^2? also contributed to soil acidification.     

Importance of Internal Proton Production for the Proton Budget in Japanese Forested Ecosystems

Annual biogeochemical fluxes (bulk precipitation, throughfall, stem flow, soil solution and vegetation uptake) of inorganic elements were observed in eight cool temperature forested ecosystems in Hokkaido, northern Japan, in order to determine the mechanisms of acid neutralization in Japanese forest ecosystems. We compared our results with the other biogeochemical studies in Japan, north Europe and US from the literature. In many Japanese forests, the internal proton production (IPS) by base cation accumulation into the vegetation was a major proton source, rather than external acidic deposition, and the IPS also affected the base cation fluxes from the mineral. IPS in Japanese forest tended to be larger than that in north Europe and US. Our results suggested that the high acid neutralizing ability of Japanese forests could be attributed to the strong relationship between the base cation buffering of the soil and the larger contribution of IPS as a proton source. acidic deposition|biogeochemical cycling|forest ecosystem|Japan|proton budget     

Soil Organic Matter Fractions in Experimental Forested Watersheds

Recent concerns about climate change and atmospheric greenhousegas concentrations have demonstrated the importance ofunderstanding ecosystem C source/sink relationships. Soilorganic matter fractionation was carried out in three paired,forested watershed sites where one of each watershed pairrepresented a different ecosystem perturbation. Theperturbations were 8 years of experimental N amendments at theBear Brook Watershed in Maine (BBWM), a 50 year old intensewildfire and subsequent regeneration at Acadia National Park(ANP), and a 17 year old whole-tree harvest at the Weymouth PointWatershed (WPW). At each site, mineral soils were sampled byuniform depth increments. Mineral soil (< 2 mm) was separatedinto light, occluded light, and heavy density fractions byfloatation in NaI solution (1.7 g cm^-3). Mineral soil (< 2mm) was also separated into particle-size fractions of sand (2.0to 0.05 mm), silt (0.05 to 0.002 mm), and clay (< 0.002 mm) bywet sieving and centrifugation. Whole soils, and density andparticle-size fractions were analyzed for total C and N. Bothfractionation schemes showed that all soil organic matterfractions had lower C/N ratios as a result of N enrichment atBBWM. At ANP, soil organic matter fractions generally had lowerC/N associated with the wildfire and subsequent shift fromsoftwood to hardwood regeneration. Few significant whole soiland soil organic matter fraction differences were associated withthe whole-tree harvest. Within watershed pairs, both density andparticle-size fractionation techniques usually indicated similarresponses. Soil organic matter fractionation results indicatedthat there were no consistent shifts in fraction distributions inresponse to perturbation that were consistent across all pairedwatershed study sites.     

Soil Acidification and Solute Budgets for Forested Lysimeters in Nordrhein-Westfalen

Solute budgets and nitrogen use were quantified in two 400 m² forested lysimeters in St. Arnold, Nordrhein-Westfalen. The lysimeters are covered by a mixture of oak-beech and Weymouth pine, respectively. The average bulk deposition between May 1985 and May 1987 of NH, SO and NO₃ was 1.1, 1.7, and 0.4 kmol_c ha^?1 yr^?1 in the deciduous stand and 2.1, 2.1, and 0.8 kmol_c ha^?1 yr^?1 in the coniferous stand. The input of N is almost completely retained in the deciduous stand. In the coniferous stand about 30% of this N-input is leached as NO₃. Due to N-transformations, total proton turnover is 4.4 kmol_c ha^?1 yr^?1 in the coniferous stand and only 2.5 kmol_c ha^?1 yr^?1 in the deciduous stand. Ca-mobilization is the major acid buffering process in both lysimeters. Only the deciduous stand was limed in 1980 (90 kmol_c/ha). Mobilization of Al is only relevant down to a soil depth of 30 cm. Below a 30 cm depth, Al is immobilized. The amounts of exchangeable and silicate-bound Ca in the soil underlying the coniferous stand are very small, but no evidence was found for explanation of the observed high Ca-mobilization by artificial Ca-sources.     

Proton Budget for a Japanese Cedar Forest Ecosystem

The proton budget for a Japanese cedar (Cryptomeria japonica) forest in Gunma Prefecture, Japan, was studied by estimating biogeochemical fluxes. The proton budgets were estimated for three individual compartments of the ecosystem: vegetation canopy, and the upper (O horizon + 0–10 cm) and lower (10–100 cm) soil layers. The dominant proton sources in the compartments were atmospheric deposition (1.2 kmol ha^?1 yr^?1), nitrification (5.1 kmol, ha^?1 yr^?1) and base-cation uptake by vegetation (8.0 kmol, ha^?1 yr^?1) respectively. These proton sources were neutralized almost completely within the individual compartments mainly by base-cation release from the canopy or the soil. The sum of internal proton sources was five times as large as that of external ones. Nitrogen input from the atmosphere was 2.2 kmol ha^?1 yr^?1, whereas its output from the lower soil layer was 3.9 kmol ha^?1 yr^?1, indicating that a net loss of nitrogen occurred in the ecosystem. However, this did not cause the acidification of soil leachates because of a sufficient release rate of base cations from the soil.     

森林生态系统土壤呼吸研究进展

森林土壤碳是全球碳库的重要组成部分,在全球碳循环方面发挥着重要作用。土壤呼吸是当前碳循环研究领域中的一个热点问题,而且目前土壤呼吸已经成为陆地生态系统中向大气释放CO2最大的源。把土壤呼吸量与植物群落生长之间的关系进行分析比较,是理解森林生态系统碳素平衡的核心。在综合介绍国内外有关土壤呼吸的各种测定方法的基础上,对国内外有关森林土壤呼吸的已有研究成果进行了述评,指出了森林土壤呼吸研究工作今后的努力方向。     

Losses of Soil Carbon upon a Fire on a Drained Forested Raised Bog

We studied the consequences of a fire that affected 29 ha of a drained forested raised bog in Tver oblast, Central European Russia. The drainage network consisted of open 1-m-deep ditches with 60 to 160 m ditch spacing. The groundwater level (GWL) varied within the studied drained bog. We used the method of assessing the loss of soil carbon (C) based on the difference between the ash concentration in the burnt peat of the upper layer and underlying unburnt layers. The carbon loss was higher near the drainage ditches than in the sites remote from ditches. The sample median values of carbon loss (kg C/m²) were estimated at 0.37 near the drainage ditches and at 0.22 for the remote sites with a distance of 160 m between ditches. They increased to 2.23 and 0.79 near and far from the drainage ditches for 106 m ditch spacing, and ranged from 1.13 to 2.10 near the drainage ditches and were equal to 0.45 at the remote sites for 60 m ditch spacing. The maximum loss of C was at the bog margin with the 70-cm-deep GWL; the sample median was equal to 2.97 kg C/m². The results obtained for C loss from the wildfire on the raised bog agree with the estimates obtained by other authors (1.45–4.90 kg C/m²) and confirm the importance of taking such loss into account in the estimates of the carbon budget of peat soils (Histosols).     

土壤动物在农业生态系统中的研究进展

近些年来随着对生态学的深入研究,人们认识到土壤动物的群落结构、功能以及在生态过程中积极的不可替代的作用,土壤动物逐渐成为生态学研究的热点之一。本文分析评价了国内关于土壤动物的研究进展。同时对国外土壤动物在土壤环境评价、凋落物分解、土壤健康的指示作用、与污染环境的关系、二氧化碳浓度对其的影响、在农业生态系统中的作用、在城市生态系统研究中的作用、在废弃物处理及土壤改良中的应用、在N循环中的作用、湿地土壤动物研究等10个方面的研究动态进行了综述。并提出了对土壤动物研究工作的几点建议。     

Effects of the Establishment of a Forested Riparian Buffer and Grazing on Soil Characteristics

Poultry-litter applications to pastures can result in relatively high soil phosphorus (P) levels, which in turn can contaminate runoff and degrade surface water quality. New management protocols for temperate grasslands are needed to reduce the risk of P transport to surface water. The effects of three land-use treatments on soil characteristics related to P runoff were investigated using small watersheds with 8% slope near Booneville, Arkansas, U.S. The land use treatments were (1) haying of bermudagrass overseeded with winter annual forage (ryegrass or rye), (2) rotationally grazed, and (3) rotationally grazed with 12-m-wide tree buffer on the downhill portion of the plot. Plots and trees were established in 2003. Annual spring application of poultry litter (5.6 Mg ha^?1) to the hayed or grazed portions of the plots was started in 2004. Grazing treatments were imposed shortly thereafter. By the summer of 2008 (4 years of treatments), soil concentrations of Bray 1–extractable P and soluble reactive P had increased significantly from approximately 40 and 4 mg P kg^?1 soil, respectively, to more than 200 and 30 mg P kg^?1 soil, respectively, in the areas of the plots receiving poultry litter. Soil bulk density in the portions of the plots being grazed had increased significantly also. The soil collected from the forested riparian buffer in 2008 had similar soil bulk densities and Bray 1–extractable P concentrations as the plots did in 2003 before treatments were imposed.     

农田生态系统杂草的养分和水分效应研究

通过田间试验研究了冬小麦田杂草的土壤养分和水分效应．发现田间保留一定量的杂草能够提高表层土壤水分含量，尤以0～20cm层次表现明显，显示出很好的土壤水分保持效应。同时在保留杂草的处理中，0～60cm土壤碱解氮储量消耗最少．速效P储量在增加．而速效K储量增加得最多。并且在冬小麦返青期不论土壤养分情况怎么样．在收获后都以保留杂草的处理土壤速效养分(碱解氮、速效磷和速效钾)储量最高．表现出较高的土壤养分供给能力。     

探讨以沙量平衡计算方法辅助土壤侵蚀监测

在简要阐明沙量平衡计算概念的基础上，提出以沙量平衡计算辅助土壤侵蚀监测之方法。分析了沙量平衡计算各组成部分与土壤侵蚀监测之间的关系，对沙量平衡计算框架下沙源监测、沉积泥沙存蓄变化监测及泥沙输出监测的应用方法及其可行性进行了探讨，明晰了以此方法辅助土壤侵蚀监测的时空问题。     

地上植食性昆虫对土壤生态系统影响的研究进展

地上地下生态系统之间存在着密切的联系,二者相互作用,共同影响陆地生态系统过程。越来越多的研究表明,地上地下之间的相互联系还受到植食性动物取食作用的调节。地上植食性昆虫不仅可以改变地上植物或动物群落,还可以间接地影响土壤生态系统中的生物群落和相关的土壤过程,进而对地上生态系统形成反馈。本文综述了地上植食性昆虫对土壤食物网中不同营养级的生物群落,以及相关土壤过程的影响;在已有研究报道的基础上,分析并归纳了地上植食性昆虫影响土壤生态系统的途径和调控因素等,旨在较为全面地总结地上植食性昆虫对土壤生态系统的间接影响以及相关的影响机制,并对今后的研究方向作了初步展望。     

农田土壤生态系统多功能性研究进展

健康土壤培育是耕地产能提升的先决条件,也是应对粮食安全和环境保护挑战,保障土壤可持续利用,实现农业绿色发展和构建生命共同体的基础。健康土壤培育的核心是实现土壤生态系统多功能性。在生态文明建设的新时代,土壤生态系统多功能性评价、培育过程及机制研究已成为全球土壤健康行动的焦点和前沿。本文系统梳理了土壤功能、土壤生态系统服务与土壤生态系统多功能性的概念,讨论了土壤生物多样性对多功能性的影响、土壤功能间的协同与权衡关系,总结了土壤功能评价及量化的方法,并提出了突破单一追求粮食高产目标,发展基于多功能性综合调控的农田健康土壤培育新思路。提出在不同层级上提高土壤多功能性的途径：在全国尺度调整土地利用方式及农业结构、区域尺度协调资源配置、景观尺度构建农业设施建设与景观格局、田块尺度优化田间土壤管理技术,全面提升土壤健康和多功能性。未来需要通过多学科交叉深入探索不同时空尺度的土壤多功能性形成与维持机理,与现代科技相结合,完善土壤功能管理相关政策与落地方案,强化土壤多功能性在可持续环境政策与管理中的多维作用,为山水林田湖草生命共同体协调发展和“碳达峰、碳中和”国家战略的实施提供重要支撑。     

土壤侵蚀对生态系统的影响

每年在世界陆地生态系统中大约有750亿t的土壤被侵蚀掉。农用地土壤流失速率在13~40 t/(hm2.a)之间,因为土壤形成非常缓慢,这就意味着土壤流失速率是更新速率的13~40倍。降雨和风力是耕地或裸地的两个主要侵蚀营力,当土壤缺乏植被覆盖保护时侵蚀就发生了。土壤侵蚀造成水分、养分、土壤有机质、生物区系、土壤厚度等的流失或减少因而使土地生产力降低。土壤侵蚀加剧了由于人口的快速增长而带来的食物短缺问题的威胁。于是人们便开垦森林以弥补荒废的侵蚀农用地的损失。     

湿地生态系统土壤氮素矿化过程研究动态

土壤氮素的矿化过程与土壤供氮能力及氮素损失密切相关,其对于氮素生物地球化学过程的生态意义重大。本文综述了当前湿地土壤氮素矿化过程的研究方法、模型表征以及影响因素的研究动态。氮素矿化过程的研究主要集中在净矿化作用方面,而其研究模型又主要包括矿化动力学模型、热力学模型和环境效应模型。影响湿地土壤氮素矿化过程的因素主要包括湿地气候条件、水文条件、土壤理化性质、枯落物性质、土壤生物区系及人类活动等。今后研究的重点应包括:(1)氮素矿化过程的驱动机制与驱动因素;(2)概念模型与应用模型的表征;(3)全球变暖、降水改变以及人为碳、氮输入对矿化过程的影响;(4)人类活动在湿地土壤氮素矿化过程中的作用。     

草地和农田生态系统中黑土活性有机碳的特征

为阐明植被覆盖与施肥管理综合作用下黑土活性有机碳的数量特征,探讨合理调控农田土壤质量的施肥模式。本试验以中国科学院海伦农业生态实验站长期定位试验为平台,对比和研究了草地与农田生态系统中不同施肥处理下土壤总有机碳、颗粒有机碳、微生物生物量碳、冷水提取有机碳以及热水提取有机碳数量上的差异及相互关系。结果表明:经过25年的自然恢复,草地生态系统中土壤有机碳及各活性有机碳的数量显著高于农田生态系统中的无肥处理(P<0.05)。农田生态系统中,化肥处理对农田土壤有机碳和活性有机碳的提高作用并不明显;经过长期化肥+有机肥处理后,农田土壤总有机碳与各活性组分的数量较无肥和化肥处理显著提高(P<0.05),除微生物生物量碳外,总有机碳与其他活性有机碳组分的数量均达到草地植被下的碳水平,土壤总有机碳及冷水和热水提取有机碳的含量与草地生态系统的差异不显著,颗粒有机碳含量比草地生态系统坛加43.7%。相关性分析表明,土壤有机碳总量、微生物生物量碳、冷水提取有机碳以及热水提取有机碳两两之间的相关性均达到显著或极显著水平。长期化肥与有机肥配施是提高黑土有机碳及其活性有机碳数量的有效措施。     

长江上游云南松水土保持林地坡面径流与侵蚀规律的研究

根据1999～2001连续3年的定位观测,研究了试验流域降水特征和森林植被与坡面径流与侵蚀的关系.结果表明:试验区的大气降水表现出明显的雨季和旱季之分,年均降水量为1 019.6 mm,雨量多集中在雨季的5～10 月份,其降水量为827.7 mm,占年降水量的81.18% ,旱季仅占18.82% .试验小流域发生地表径流的形式为蓄满产流,同时大气降水分配不均,雨季降水的过分集中并形成的大雨或暴雨,是导致地表径流及其侵蚀的主要原因.与裸地相比,林地坡面径流与侵蚀的削减效应显著.但森林削减坡面径流与侵蚀的效益与森林树种自身的生物、生态学特性及其林分结构状况等密切相关.     

土壤中细菌产氨代谢对农田生态系统的意义

土壤细菌利用尿素产氨不仅可以直接影响土壤中氮源的循环利用和土壤氮素肥力,并且有助于酸化土质的改良。该文就土壤中细菌利用尿素产氨的生物学特征及分子调控机制,影响土壤尿素酶活性的土壤化学特性、环境因素、尿素来源以及微生物间相互作用进行等研究进展进行了综述分析。指出土壤中尿素酶活性是检测土壤质量和土壤肥力的重要指标之一,它与固氮作用、土壤改良和土壤中其他产氨代谢有密切关系,土壤中尿素酶的活性指标对土壤氮素肥力评价和农作物生产具有重要意义。     

基于生态系统多功能性的农田土壤健康评价

农田土壤健康状况不仅影响作物产量和品质,还影响大气、水环境质量和生物安全,因而农田土壤健康评价应将土壤生产能力与生态环境效应结合考虑。基于土壤生态系统多功能性,将土壤功能归纳为作物生产、持水净水、养分运移与缓冲、碳固存及栖息地与多样性等5项功能。进一步针对每项功能,按照固有属性和动态属性两个方面分别选取基础项指标,同时考虑具有区域特点的威胁土壤功能发挥的限制项指标,并采用2个乘数来体现限制因子对固有和动态属性影响的差异性,共同构建农田生态系统土壤健康评价指标体系。以中国生态系统研究网络(CERN)内位于黄淮海平原的封丘、栾城和禹城3个实验站典型农田生态系统为例,应用所建立的指标体系,采用灰色关联分析法对其土壤健康状况进行综合评价。结果显示,3个农业生态实验站土壤健康状况总体相当且处于较高水平,但仍有所差异,表现为禹城>栾城>封丘,且作物生产功能与产量R~2达到0.60,验证表明该评价体系比较合理。因此,基于多功能性的土壤健康评价方法可为进一步探究土壤健康长期变化趋势,实施土壤资源有效管理提供一定参考。     

黑土农田生态系统的保育与发展

东北黑土区是我国的重要商品粮基地,其利用现状不容乐观.在黑土农田生态系统的水、肥和信息资源的研究方面取得了大量的成果,为保护利用提供了科学依据.