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1.
P. S. Lozovitsii 《Eurasian Soil Science》2012,45(3):290-302
The results of long-term studies (1957–2007) of the changes in the morphology of soil profiles and in the reserves and fractional
composition of the humus in the soils of the Ingulets irrigation system are discussed. After 50 years of irrigation, the boundaries
of the genetic horizons shifted downward by 15–30 cm. The redistribution of the humus took place: its content decreased to
a low level in the plow layer of the irrigated and rainfed soils and significantly increased in the layer of 60–100 cm so
that the reserves of humus in the layer of 0–100 cm somewhat increased and corresponded to a moderate level. The distribution
of humus in the soil profiles was characterized by the gradual lowering down the soil profile. The concentration of nitrogen
in the humus of the irrigated southern chernozems was very low. The degree of humification of the soil organic matter was
high. The humus was of the humate type in the upper horizons and of the fulvate-humate type in the lower horizons. 相似文献
2.
I. V. Ivanov O. S. Khokhlova V. V. Galitskii O. A. Chichagova E. P. Zazovskaya 《Eurasian Soil Science》2012,45(8):802-810
The dynamics of the 14C content in the humus of chernozems in 1900?C2008 are considered. The elevated 14C content in the atmosphere because of nuclear weapons tests has led to the contamination of humus with bomb radiocarbon. In 1966?C1968, the 14C reserves in the profiles of chernozems exceeded the background ones by 15%; in 1978, by 12%; and, in 1998, by 2%. By the year of 2008, its reserves became equal to the background ones. The 14C distribution along the soil profiles changed. By 1978, the 0- to 30-cm-thick soil layer became free from radiocarbon due to its self-purification; however, at depths of 40?C70 and 100?C115 cm, its weak accumulation was registered. By 2008, the whole soil profile was free from 14C. The main mechanism of the soil self-purification from radiocarbon is suggested to be the constant substitution of fragments of humus compound structures for those of fresh organic matter entering the soils with the 14C content being in equilibrium with the atmospheric one, i.e., due to the renewal of the carbon in the humus. The rate of the carbon renewal and its migration in the soils are assed based on the 14C concentrations in the humus. 相似文献
3.
A method for the determination of the humus content and reserves in the landscapes was elaborated based on the landscape-geophysical
method of studying natural territorial complexes (NTCs). Some characteristics of the spatial humus distribution in the landscapes
of Georgia were revealed. For this purpose, data of long-term (1980–2005) landscape-geophysical observations and a great body
of literature materials were used. For the determination of the duration of the favorable daily NTC states, the data of Georgian
meteorological stations were taken. A relation between the humus amount and the state of the stex layer (pedostexes) is shown.
Special attention is paid to revealing the landscapes with the maximal humus accumulation and finding out the duration of
the favorable states of the NTC. A map of the humus content and reserves in different landscapes of Georgia was compiled. 相似文献
4.
On the basis of a large volume of literature and original data, the high content (1–7%) of organic matter in the mineral layer
of loamy permafrost-affected soils of coastal lowlands in East Siberia (from the lower reaches of the Lena River to the lower
reaches of the Kolyma River) has been statistically proved. In most cases, the reserves of Corg in the mineral layer of these soils exceed those in the surface organic horizons and constitute 60–90% of the total soil
pool of Corg. The enrichment of the mineral layer with Corg is due to the cryogenic retention (retenization) of humus (the illuviation and accumulation of colorless humic substances
above permafrost) and the cryogenic mass exchange (mechanical admixture of organic matter from the upper organic horizons
into the mineral layers). The analysis of 60 soil profiles showed that the accumulation of organic matter above the permafrost
table is observed in 43% of cases; in general, the organic matter distribution in the soil profiles is highly variable. A
specific type of colorless humus is accumulated above the permafrost table. The mechanisms of its precipitation and transformation
in the profile require further studies. 相似文献
5.
模拟氮沉降对湿性常绿阔叶次生林土壤碳氮组分和酶活性的影响 总被引：5，自引：4，他引：1
为了研究氮沉降对次生林土壤碳氮组分和酶活性的影响,以华西雨屏区湿性常绿阔叶次生林为对象,从2014年1月起进行野外定位模拟氮沉降试验,分别设置对照(CK,+0 g/(m^2·a))、低氮(LN,+5 g/(m^2·a))和高氮(HN,+15 g/(m^2·a))3个氮添加水平。在氮沉降进行27个月后,按照腐殖质层和淋溶层表层进行取样,测定不同土层土壤总有机碳(TOC)、可浸提溶解性有机碳(EDOC)、易氧化碳(ROC)、全氮(TN)、硝态氮(NO_3^-—N)和铵态氮(NH_4^+—N)含量以及蔗糖酶、脲酶、酸性磷酸酶和多酚氧化酶活性。结果表明:模拟氮沉降显著增加该次生林腐殖质层土壤的TOC和NH_4^+—N含量,显著增加腐殖质层和淋溶层表层土壤的NO_3^-—N含量,腐殖质层土壤C/N显著升高。淋溶层表层土壤TOC、NH_4^+—N、C/N以及2层土壤的EDOC、ROC、TN和NH_4^+—N/NO_3^-—N均无显著影响。2层土壤的多酚氧化酶活性均随着氮添加量的升高而降低,其中淋溶层表层达到显著差异。模拟氮沉降对蔗糖酶、脲酶和酸性磷酸酶活性均无显著影响。腐殖质层中,NH_4^+—N和NO_3^-—N含量与TOC含量存在极显著正相关关系。2层土壤的多酚氧化酶活性均与NO_3^-—N含量呈极显著负相关。结果说明,模拟氮沉降使该次生林中原本较高的腐殖质层土壤TOC含量进一步显著增加,并且促进土壤无机氮的积累,而模拟氮沉降对多酚氧化酶的抑制作用更加有利于土壤有机质的积累。 相似文献
6.
Total S content of the humus layer was determined from Scots pine forests in the surroundings of Oulu, an industrialized city in northern Finland. The S content nearest the city center and emission sources (zone IV; bar x=3870 μg g?1 on an organic matter basis) was about twice as high as in three background areas (80 to 170 km from the city) and about 40% higher than at the sites which were ca 20 km from the main emission sources (zone I). The estimated accumulation of S in humus layer was, on average, 0.4 to 0.6 g m?2 yr?1 in the most polluted study sites and 0.1 to 0.2, 0.2 to 0.3 and 0.4 to 0.5 g m?2 yr?1 in zones I, II, and III, respectively. 相似文献
7.
Lumbricus terrestris L. distribution within an experimental humus mosaic in a mountain spruce forest
An experiment was designed at a mountain site to study the distribution of adult Lumbricus terrestris in relation to a small-scale mosaic of humus forms representative of different stages of a spruce forest ecosystem. Good
agreement was found between distribution in the mosaic and that in the field. ANOVA tests demonstrated the strong influence
of humus form on earthworm abundance when comparing a vermimull (high earthworm burrowing activity) taken from a spruce regeneration
site (61.8 individuals m–2) with a leptomoder (no earthworm burrowing activity) taken from a 60-year-old spruce stand (6.2 individuals m–2). Other humus forms were intermediate (mean density 34.6 individuals m–2). The same pattern was found with individual biomass, but with lower significance. Main differences observed in the experimental
design were attributed to the immediate carrying density of the humus forms. A distinction was made between humus profiles
built up with or without spruce cover. In the latter case (regeneration site and bilberry heath), the immediate carrying capacity
indicated by the experimental approach overestimated the field density by a factor of 4. Under spruce this overestimate was
even higher (approximately 10 times too high in an adult spruce stand (160 years old) and 30 times too high under moss cover).
The increase in density due to experimental conditions was not determined for leptomoder humus accumulated under the actively
growing spruce stand (60 years old) since the earthworm density was near zero in both cases. Relationships between humus form
and earthworm populations are discussed.
Received: 9 June 1997 相似文献
8.
The soil formation was studied in the 21- to 35-year-old pine plantations created on the overburden dumps of the Nazarovskaya
Depression without applying the material of the humus horizon. The surface technogenic formations under the pine plantations
belong to the group of naturfabricats (surface formations devoid of the humus horizon and composed of natural substrate).
The morphological characteristics, bulk chemical and particle-size compositions, and labile properties of the soils indicate
that the accumulation and transformation of organic matter are dominant processes in the artificially planted forests. The
accumulation of organic residues and destruction and humification are tightly related to the environmental conditions transformed
by the technogenesis and conceal other processes forming the soil profiles. Quasizems created for agricultural production
purposes were the objects of the study. They were formed by covering the technically planned overburden rocks with the material
of humus layers. The thickness of the humus horizons of the quasizems varies greatly (25–64%); the variation of the humus
reserves in them is 34–122%. Middle-profile horizons have not been formed by the present time. 相似文献
9.
全氮(TN)作为土壤团聚体形成的胶结物质之一,能加速不同粒级团聚体之间的转化。以黄土高原王茂沟小流域为研究对象,采用"S"法及挖剖面法对坡耕地、草地、灌木地、林地及梯田0—60 cm土壤进行分层取样,以坡耕地为对照,探究4种生态建设下土壤团聚体稳定性及其TN含量,分析不同深度(0—20,20—40,40—60 cm)、不同粒级(5,5～2,2～1,1～0.5,0.5～0.25,0.25 mm)土壤团聚体TN贡献率。结果表明:生态建设显著提高了土壤大团聚体含量,其中草地、林地与坡耕地相比,表层土壤5 mm团聚体分别增加469%和438%,土壤团聚体稳定性(MWD、GMD)增加,在垂直方向上则表现为团聚体稳定性随土层深度增加而降低。较之坡耕地,草地、灌木地、林地及梯田可在不同程度上提高土壤团聚体TN含量,其中林地团聚体TN储量(36.53 kg/m~2)最高,灌木地(32.12 kg/m~2)、草地(20.30 kg/m~2)及梯田(18.62 kg/m~2)TN储量较坡耕地分别增加131%,46%,34%,随着土层深度增加,不同生态建设类型对团聚体TN含量的影响逐渐弱化。随着坡耕地-草地-灌木地-林地的自然演替过程,0.25 mm团聚体TN贡献率呈降低趋势,梯田能够在一定程度上改良坡耕地的土壤结构,粒径范围在5～0.25 mm的土壤团聚体TN含量近乎达到草地的恢复水平,但5 mm团聚体的恢复空间尚且较大。 相似文献
10.
The total mercury content has been determined in gray forest soils, chernozems, chestnut soils, and in different parent materials
in the Transbaikal region. The mercury content is below the clarke value in the intrusive, effusive, and alluvial soil-forming
rocks (0.004–0.024 mg/kg). In the humus horizons of the soils, it reaches 0.011–0.026 mg/kg, which is higher than the clarke
value for the pedosphere. The mean background content of mercury in the soils of the Transbaikal region is 0.018 mg/kg. No
significant positive correlation between the mercury content and the humus content of the soils has been revealed. 相似文献
11.
V. E. Prikhod’ko I. V. Ivanov D. V. Manakhov E. V. Manakhova 《Eurasian Soil Science》2012,45(8):725-739
Soils of the Arkaim Reserve in the area around a unique settlement-fortress of the Bronze Age in Chelyabinsk oblast have been studied. These soils are generally typical of the entire Trans-Ural Plateau. The soil properties are characterized in detail on the basis of factual data on 170 soil pits and four soil catenas. The soil cover of the reserve is specified into six geomorphic groups: (a) denudational surfaces of the low mountains, (b) accumulative-denudational surfaces of the low mountains, (c) denudational-accumulative plain surfaces, (d) lacustrine-alluvial plain surfaces, (e) floodplain surfaces, and (f) slopes and bottoms of the local ravines and hollows. Chernozems occupy about 50% of the reserve; solonetzes and saline soils, 32%; meadow chernozems, 7%; and forest soils, 1%. The soils of the reserve are relatively thin; they have a distinct tonguing of the humus horizon and are often saline and solonetzic. The latter properties are inherited from the parent materials and are preserved in the soils for a long time under the conditions of a dry continental climate. The genetic features of the soils differ in dependence on the composition and age of the parent materials. With respect to the thickness of the soil profiles and the reserves of soil humus, the soils can be arranged into the following lithogenic sequence: the soils developed from the eluvium of igneous rocks-redeposited kaolin clay-montmorillonite-hydromica nonsaline and saline loams and clays. The content of Corg in the upper 20 cm varies from 2.5 to 5.6%, and the reserves of Corg in the layers of 0?C0.5 and 0?C1.0 m reach 57?C265 and 234?C375 t/ha, respectively. The soils of pastures subjected to overgrazing occupy two-thirds of the reserve. Their humus content is 10?C16% higher in comparison with that in the analogous plowed soils. Another characteristic feature of the humus in the soils of the pastures is its enrichment in the labile fraction (28?C40% of Corg). 相似文献
12.
A. A. Larionova A. M. Ermolaev V. I. Nikitishen V. O. Lopes de Gerenyu I. V. Evdokimov 《Eurasian Soil Science》2009,42(12):1364-1373
The effect of different land-use practices on the carbon budget in old arable gray forest soils of Russia was studied in field
experiments. A short-term (for 6–7 years) cessation of mineral fertilization had no negative effects on the carbon budget
in the agrocenoses studied. Only the combination of zero fertilization with the return to monoculture and the introduction
of black fallows created a negative budget of humus in the soil. The regrassing of the eroded arable soil for 24 years increased
the humus reserve in the 0- to 60-cm layer by a factor of 1.6–1.7. The average annual accumulation of carbon and nitrogen
after the restoration of the perennial vegetation was 106–128 g C/m2 and 11–16 g N/m2, respectively. 相似文献
13.
水氮对新疆南部麦后复种饲料油菜产量和品质的影响 总被引：2，自引：1，他引：1
采用完全随机区组田间试验研究了水氮对麦后复种饲料油菜产量及品质的影响,运用模糊相似优先比法分析了不同水氮处理下油菜产量及其4个典型饲料品质指标的变化特征。试验设置灌溉定额和施氮量2个因素：灌溉定额设置3 000 m3·hm-2（低水）、4 500 m3·hm-2（中水）和6 000 m3·hm-2（高水）3个水平;施氮量设置140.6 kg（N）·hm-2（低氮）、187.5 kg（N）·hm-2（中氮）和234.4 kg（N）·hm-2（高氮）3个水平。研究结果表明：适宜的水氮供应对饲料油菜单株鲜重、干重、产量、品质有显著的互作优势,水氮供应量过量或者不足,互作优势减弱。相同灌溉定额下饲料油菜单株鲜重、干重和产量随着施氮量的增加而提高;相同施氮条件下,随着灌水量的增加单株鲜重、干重和产量逐渐提高;提高灌溉定额的增产效应优于增氮,高水+中氮处理较低水+低氮处理产量提高86.90%。施氮量和水氮互作显著影响饲料油菜品质,中水中氮处理粗蛋白含量较高水高氮处理提高36.91%。中水低氮处理中性洗涤纤维含量最低,为32.66%,显著低于高水高氮处理;而高水低氮处理酸性洗涤纤维含量最低,为24.74%,较高水高氮处理低16.49%。高水高氮处理的粗脂肪含量最高（1.45%）。综合考虑产量与品质,新疆南部地区饲料油菜适宜的水氮措施为中水高氮[6 000 m3·hm-2,187.5 kg（N）·hm-2]。 相似文献
14.
Zhi-Ping Wang Xiao-Peng Li Rick Pelletier Scott X. Chang Edward W. Bork 《Soil Use and Management》2022,38(2):1189-1202
High heterogeneity in the spatial distribution of soil organic carbon (SOC) in grasslands causes uncertainty in estimating its content and storage. In this study, we investigated the spatial distribution of SOC content and storage in the prairies of southern Alberta, Canada, and how it is affected by land use such as irrigated cropping and other environmental conditions such as cattle grazing, slope landscape position and dominant plant species. The mean SOC content was determined to be 11.5 g kg–1 (range: 8.9 to 22.4 g kg–1) in the 0–10 cm layer and 6.8 g kg–1 (range: 4.0 to 13.3 g kg–1) in the 10–30 cm layer; mean SOC storage was 1.59 kg C m–2 (range: 1.23 to 2.78 kg C m–2) in the 0–10 cm layer and 2.07 kg C m–2 (range: 1.21 to 3.62 kg C m–2) in the 10–30 cm layer. The SOC content was significantly affected by slope position in both the 0–10 and 10–30 cm layers, in the following order: bottom >middle > top position. Moreover, SOC storage was higher in sites dominated by shrubs than graminoid/forb communities. Thus, SOC content and storage had distinctly clustered spatial patterns throughout the study area and were significant differences between the 0–10 and 10–30 cm soil layers. Prior land-use change from arid grassland to irrigated cropland increased SOC content and storage in bulk soils. 相似文献
15.
在分析陕西省境内9个黑垆土剖面成土环境、剖面形态特征及理化性质的基础上,按照中国土壤系统分类高级及基层分类检索标准,确定了其在中国土壤系统分类中的归属。9个黑垆土剖面的腐殖质层厚度介于30～120 cm,通体均具有强石灰反应,CaCO_3含量介于12.5～189.5 g/kg,其中6个剖面具有30～45 cm的堆垫层。黑垆土共包括淡薄表层、暗沃表层、雏形层、黏化层、钙积层5个诊断层和堆垫现象、钙积现象、盐积现象3个诊断现象,均腐殖质特性、温性土壤温度状况、半干润土壤水分状况以及石灰性4个诊断特性。9个黑垆土剖面在高级分类上可检索为淋溶土和雏形土2种土纲,向下继分为普通钙积干润淋溶土、钙积暗沃干润雏形土、钙积简育干润雏形土以及普通简育干润雏形土4个亚类;其土族鉴别特征可分为黏壤质混合型温性、壤质硅质混合型石灰性温性、壤质混合型温性等6个土族以及胡家庙系、崾崄系、崔木系等9个土系。但目前的系统分类检索结果未能体现黑垆土具有深厚腐殖质层及堆垫现象的典型特性,因此黑垆土的系统分类归属仍需开展深入研究,同时建议新增堆垫干润雏形土土类或堆垫简育干润雏形土亚类,以体现人为农业生产活动对黄土高原地区土壤的影响。 相似文献
16.
A. V. Bogorodskaya T. V. Ponomareva D. Yu. Efimov A. S. Shishikin 《Eurasian Soil Science》2017,50(6):720-731
Changes in soil microbial processes and phytocenotic parameters were studied in clearings made for power transmission lines in the subtaiga and southern taiga of Central Siberia. In these clearings, secondary meadow communities play the main environmental role. The substitution of meadow vegetation for forest vegetation, the increase in the phytomass by 40–120%, and the transformation of the hydrothermic regime in the clearings led to the intensification of the humus-accumulative process, growth of the humus content, reduction in acidity and oligotrophy of the upper horizons in the gray soils of the meadow communities, and more active microbial mineralization of organic matter. In the humus horizon of the soils under meadows, the microbial biomass (Cmicr) increased by 20–90%, and the intensity of basal respiration became higher by 60–90%. The values of the microbial metabolic quotient were also higher in these soils than in the soils under the native forests. In the 0- to 50-cm layer of the gray soils under the meadows, the total Cmicr reserves were 35–45% greater and amounted to 230–320 g/m3; the total microbial production of CO2 was 1.5–2 times higher than that in the soil of the adjacent forest and reached 770–840 mg CO2-C/m3 h. The predominance of mineralization processes in the soils under meadows in the clearings reflected changes in edaphic and trophic conditions of the soils and testified to an active inclusion of the herb falloff into the biological cycle. 相似文献
17.
云南省森林生态系统在全球碳循环及平衡中具有不可替代的作用,但其森林土壤腐殖质组分特征及其影响因素尚不十分清楚。基于云南省不同林区采集的88个表层土样,通过描述性统计和回归分析量化了海拔、土壤类型、坡向和坡度、年均温和年降水量对土壤腐殖质组分分布影响的相对重要性,探讨云南省森林土壤腐殖质组分分布特征。结果表明:云南省森林土壤表层有机碳含量为8.40～199.73 g·kg~(–1),平均含量为51.37 g·kg~(–1),土壤可提取腐殖质碳含量为2.54～84.02 g·kg~(–1),平均含量为24.52 g·kg~(–1);胡富比均值小于1,土壤腐殖质聚合度较低;土壤腐殖质组分分布特征总体表现为滇西北、滇东北部较高,滇中、滇南部较低;土壤类型、海拔、年均温是影响云南省森林土壤腐殖质组分含量的主导因子,各因素的贡献程度总体呈现为土壤类型最高,其次是年均温、海拔,这说明土壤类型对森林表层土壤腐殖质的积累起重要作用。 相似文献
18.
The stocks of organic carbon and mean rates of the CO2 emission during the growing season (May–September) and the entire year were estimated in a sequence of grass ecosystems along the transect encompassing chestnut and meadow-chestnut steppe soils, marsh and meadow alluvial soils, and a haloxerophytic community on a typical solonchak. The total stocks of organic carbon comprised 6.17–9.70 kg С/m2 in steppe, 7.41–10.04 kg С/m2 in floodplain, and 4.74 kg С/m2 in haloxerophytic ecosystems. The portion of humus carbon in the upper 50-cm-thick soil layer comprised 79–92% of the total carbon stock. The mean daily CO2 emission (С–CO2/(m2 day)) from alluvial soils was moderate (3.3–4.9) or low (1.5–2.5). The dependence of the CO2 emission on the moistening of steppe soils, temperature of alluvial soils, and temperature and moistening of solonchak was revealed. In comparison with the CO2 emission from the zonal chestnut soil, its mean values during the growing season and the entire year were 1.2 times higher for the meadowchestnut soil, 3.3 times higher for the marsh alluvial soil, 2.3 times higher for the meadow alluvial soil, and 1.7 times higher for the solonchak. The portion of the CO2 emission beyond the growing season in the mean annual emission averaged 19.8–24.2% and depended on the type of grass ecosystem and on weather conditions of particular years. The sink of carbon in the grass ecosystems exceeded carbon emission, especially in the steppe ecosystems. 相似文献
19.
The main energy sources of soil microorganisms are litter fall, root litter and exudation. The amount on these carbon inputs vary according to basal area of the forest stand. We hypothesized that soil microbes utilizing these soil carbon sources relate to the basal area of trees. We measured the amount of soil microbial biomass, soil respiration and microbial community structure as determined by phospholipid fatty acid (PLFA) profiles in the humus layer (FH) of an even-aged stand of Scots pine (Pinus sylvestris L.) with four different basal area levels ranging from 19.9 m2 ha−1 in the study plot Kasper 1 to 35.7 m2 ha−1 in Kasper 4. Increasing trend in basal respiration, total PLFAs and fungal-to-bacterial ratio was observed from Kasper 1 to Kasper 3 (basal area 29.2 m2 ha−1). The soil microbial community structure in Kasper 3 differed from that of the other study plots. 相似文献
20.
Cesium and soil carbon in a small agricultural watershed 总被引：8，自引：1，他引：8
Scientific, political, and social interests have developed recently in the concept of using agricultural soils to sequester carbon. Studies supporting this concept indicate that soil erosion and subsequent redeposition of eroded soils in the same field may establish an ecosystem disequilibrium that promotes the buildup of carbon on agricultural landscapes. The problem is to determine the patterns of soil erosion and redeposition on the landscape and to relate these to soil carbon patterns. Radioactive 137cesium (137Cs) can be used to estimate soil erosion patterns and, more importantly, redeposition patterns at the field level. The purpose of this study was to determine the relationship between 137Cs, soil erosion, and soil carbon patterns on a small agricultural watershed. Profiles of soils from an upland area and soils in an adjacent riparian system were collected in 5 cm increments and the concentrations of 137Cs and carbon were determined. 137Cs and carbon were uniformly mixed in the upper 15–20 cm of upland soils. 137Cs (Bq g−1) and carbon (%) in the upland soils were significantly correlated (r2=0.66). Carbon content of the 0–20 cm layer was higher (1.4±0.3%) in areas of soil deposition than carbon content (1.1±0.3%) in areas of soil erosion as determined by the 137Cs technique. These data suggest that measurements of 137Cs in the soils can be useful for understanding carbon distribution patterns in surface soil. Carbon content of the upland soils ranged from 0.5 to 1.9% with an average of 1.2±0.4% in the 0–20 cm layer while carbon below this upper tilled layer (20–30 cm) ranged from 0.2 to 1.5% with an average of 0.5±0.3%. Total carbon was 2.66 and 3.20 kg m−2 in the upper 20 cm and upper 30 cm of the upland soils, respectively. Carbon content of the 0–20 cm layer in the riparian system ranged from 1.1 to 67.0% with an average 11.7±17.1%. Carbon content below 20 cm ranged from 1.8 to 79.3% with an average of 18.3±17.5%. Soil carbon in the upper 20 cm of the riparian profile was 10.1 and 15.0 kg m−2 in the upper 30 cm of the riparian profiles. This is an increase of organic carbon by a factor of 3.8 and 4.7 for the upper 20 cm and upper 30 cm of the riparian profiles, respectively, when compared to the upland soil profiles. 相似文献