Caesium-137 estimates of erosion in agricultural areas     

R. A. Sutherland 《水文研究》1992,6(2):215-225

Sediment redistribution within near-level agricultural fields in the Gray Wooded soil zone of Saskatchewan was studied using the artificial environmental tracer caesium-137 (¹³⁷Cs). the objective of this study was to estimate erosion rates caused by wind erosion, and land clearing techniques (i.e. bulldozing). Net rates of erosion and deposition were quantified over the past 30 years on three fields. Wind erosion was estimated to be approximately 1.0 t ha^?1 y^?1 on a near-level field, with 50 per cent of the sampling sites having erosion rates in excess of soil formation. Bulldozing produced median net sediment flux values of between 40 and 90 t ha^?1 y^?1. in addition, between 65 and 85 per cent of the sampling sites had erosion rates in excess of the maximum tolerable limit (i.e. 11.0 t ha^?1 y^?1). These results indicate significant accelerated erosion results from land clearing techniques used in central Saskatchewan. Bulldozing of the fields removed the LFH-horizon and exposed the underlying mineral horizon. Bulk densitites of the 0 to 15 cm layer in the cleared fields were 27 to 55 per cent greater than the comparable depth increment within the undisturbed forest site. Organic carbon concentrations within the 1930s, 1979, and 1987 fields were decreased by 47, 42, and 37 per cent, respectively following cultivation and bulldozing. Decreases in total nitrogen for the cultivated fields ranged from 33 to 38 per cent.  相似文献   

Transport of nitrogen in soil water following the application of animal manures to sloping grassland     

R. J. PARKINSON  P. GRIFFITHS  A. L. HEATHWAITE 《水文科学杂志》2013,58(1):61-73

Abstract

A field experiment was conducted on a sloping grassland soil in southwest England to investigate the downslope transport of nitrogen in soil water following the application of cattle manure, slurry and inorganic fertilizer. Transport of nitrogen (N) species was monitored on hydrologically isolated plots. Manure (50 t ha^?1), slurry (50 m³ ha^?1) and fertilizer (250 kg N ha^?1) were applied in February/March 1992. Subsurface water movement, by both matrix and preferential flow, was the dominant flow route during the experiment. Subsurface and surface nutrient flow pathways were monitored by analysing soil water and surface runoff for NO₃-N, NH₄-N and total N. Subsurface flow chemistry was dominated by NO₃-N, with concentrations usually between 2 and 5 mg NO₃ ?N dm^?3. Differences between fertilizer and manure treatments and the untreated control were not significant. Significantly elevated NO₃-N concentrations were observed in soil water in the buffer zone, indicating the importance of a buffer zone at least 10 m wide between manure spreading zones and an adjacent water course.  相似文献   

Influence of Vegetation Characteristics on Soil Denitrification in Shoreline Wetlands of the Danjiangkou Reservoir in China     

Wenzhi Liu  Guihua Liu  Quanfa Zhang 《洁净——土壤、空气、水》2011,39(2):109-115

Soil denitrification in reservoir shoreline wetlands is an important process for removing excess inorganic nitrogen from upland runoff and controlling eutrophication in aquatic ecosystems. As yet, little is known about the influence of vegetation characteristics on the soil denitrification potential in reservoir shoreline wetlands, although vegetation can affect both denitrifying bacteria and soil properties. In this study, we measured the spatial variability of denitrification enzyme activity (DEA) using acetylene block method in shoreline wetlands of the Danjiangkou Reservoir, a water source of the South‐to‐North Water Transfer Project in China. Results indicated that DEA ranged from 0.001 to 2.449 µg N (N₂O) g^?1 h^?1, with a mean of 0.384 µg N (N₂O) g^?1 h^?1. DEA varied significantly among five representative plant communities and the highest DEA (0.248–2.449 µg N (N₂O) g^?1 h^?1) was observed in the Polygonum hydropiper community. Plant biomass and vegetation cover were significantly and positively related to DEA and together explained 44.2% of the total variance. These results suggest that vegetation characteristics should also be considered in assessing soil denitrification capacity and restoring shoreline wetlands for nitrogen pollution removal in the Danjiangkou Reservoir after dam heightening.  相似文献   

Dynamics of soil erosion rates and controlling factors in the Northern Ethiopian Highlands – towards a sediment budget     

Jan Nyssen  Jean Poesen  Jan Moeyersons  Mitiku Haile  Jozef Deckers 《地球表面变化过程与地形》2008,33(5):695-711

This paper analyses the factors that control rates and extent of soil erosion processes in the 199 ha May Zegzeg catchment near Hagere Selam in the Tigray Highlands (Northern Ethiopia). This catchment, characterized by high elevations (2100–2650 m a.s.l.) and a subhorizontal structural relief, is typical for the Northern Ethiopian Highlands. Soil loss rates due to various erosion processes, as well as sediment yield rates and rates of sediment deposition within the catchment (essentially induced by recent soil conservation activities), were measured using a range of geomorphological methods. The area‐weighted average rate of soil erosion by water in the catchment, measured over four years (1998–2001), is 14·8 t ha^?1 y^?1, which accounts for 98% of the change in potential energy of the landscape. Considering these soil loss rates by water, 28% is due to gully erosion. Other geomorphic processes, such as tillage erosion and rock fragment displacement by gravity and livestock trampling, are also important, either within certain land units, or for their impact on agricultural productivity. Estimated mean sediment deposition rate within the catchment equals 9·2 t ha^?1 y^?1. Calculated sediment yield (5·6 t ha^?1 y^?1) is similar to sediment yield measured in nearby catchments. Seventy‐four percent of total soil loss by sheet and rill erosion is trapped in exclosures and behind stone bunds. The anthropogenic factor is dominant in controlling present‐day erosion processes in the Northern Ethiopian Highlands. Human activities have led to an overall increase in erosion process intensities, but, through targeted interventions, rural society is now well on the way to control and reverse the degradation processes, as can be demonstrated through the sediment budget. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Soil erosion and overland flow in forested areas with pine plantations at coastal mountain range,central chile     

C. E. Oyarzun  L. Pea 《水文研究》1995,9(1):111-118

The effects of timber-cutting on sediment concentrations, soil loss and overland flow in an insigne pine (Pinus radiata) plantation were studied in a mountain watershed of the Cordillera de la Costa, central Chile. Soil formation rates for the lithological conditions of the watershed were estimated. Soil loss measurements on the plantation were taken in 100 m² plots, equipped with Coshocton samplers, during the years 1991 and 1992. Treatments were: clear-cutting no residues/burned, clear-cutting with residues and undisturbed controls. First-year soil losses were greater from the no residues/burned (2128 kg ha^?1) than from the residues (1219 kg ha^?1) or undisturbed (48 kg ha^?1) plots. During the second post-treatment year, soil loss was greater from the burned plots (1349 kg ha^?1) than from the residues (243 kg ha^?1) or the undisturbed (72 kg ha^?1) plots. Sediment concentrations for the three treatments were 561, 340 and 59 mgl-¹ during the first year, and 400, 150 and 83 mgl^?1 in the second year. Runoff from the no residues/burned plots was greater than from residues or undisturbed plots during the two post-treatment years. Long-term soil losses were projected to average 240 kg ha^?1 yr^?1 from areas without residues/burned and 120 kg ha^?1 yr^?1 in areas with residues treatment, over a 25 year rotation period, whereas control areas were projected to average 60 kg ha^?1 yr^?1.  相似文献   

Potassium and Residue Management Options to Enhance Productivity and Soil Quality in Zero Till Maize–Wheat Rotation     

Raghavendra Madar  Yudh Vir Singh  Mahesh Chand Meena  Tapas Kumar Das  Sunita Gaind  Rakesh Kumar Verma 《洁净——土壤、空气、水》2020,48(3)

Crop residue burning and imbalanced use of chemical fertilizers in intensive cereal–cereal rotations are present ecological threats in any agro‐ecosystem of the world. Therefore, identification of best suitable agricultural practices can be a feasible option. The present experiment was initiated in 2013 and consisted of four residue levels (0, 2, 4, and 6 Mg ha^?1) and five potassium (K) levels (0, 50, 100, 150% recommended dose of K and 50%RDK+K solubilizing bacteria, KSB). Crop residue (CR) and K management significantly improve crop and soil quality associated parameters. Among the treatments, maximum increase in crop growth, physiological parameters, grain yield, quality aspects, and water productivity are recorded with the application of 4–6 Mg ha^?1 CR. Application of 50%RDK+KSB also significantly increases crop and soil related parameters. Soil quality indicators (bulk density, pH, electrical conductivity, and available micronutrients) do not vary significantly with CR and K management. Change in soil organic carbon status, soil enzymes, and potassium‐solubilizing bacterial count are significantly increased with 4–6 Mg ha^?1 CR and application of 50%RDK+KSB, and this is in accordance with correlation study carried out. Therefore, it is concluded that CR retention (4–6 Mg ha^?1) and reduction of inorganic K fertilizer by 50% and inoculation of KSB enhance the soil quality indicators and thereby improve crop growth, physiological parameters, grain yield, and quality aspects along with water productivity under zero till maize–wheat rotation.  相似文献   

Dynamic Changes of Stipa bungeana Steppe Species Diversity as Better Indicators for Soil Quality and Sustainable Utilization Mode in Yunwu Mountain Nature Reserve,Ningxia, China     

Jie Cheng  Jimin Cheng  Tianming Hu  Hongbo Shao  Jianming Zhang 《洁净——土壤、空气、水》2012,40(2):127-133

Due to serious degradation of typical Stipa bungeana steppe community on the Loess Plateau, a 26‐year (1982–2007) experiment has been carried out by methods of forbidden grazing, cutting, and rotational grazing. Our results show that the process of succession of long‐term enclosed S. bungeana community can be divided into two stages: 1980–1996, the forward succession stage, when the species diversity and biomass reach the peak (33.7 species/m² and 1349.41 g/m², respectively); 1997–2007, the slow succession stage, when the gradually thickening of litter layer (litter depth reaches 3–5 cm) directly causes the reduction of species diversity and biomass to 19.1 species/m² and 863.19 g/m², respectively. While under the cutting and rotational grazing methods, grassland succession can be divided into four stages: 1st–5th year, the continuing growth stage; 6th–9th year, the vigorous competing stage; 10th–15th year, the aggregation growth stage of constructive species with biomass reaching the peak (1444.19 g/m²); and 16th–23rd year, stable growth stage of constructive species, which form sub‐climax and are eventually dominated by S. bungeana, with the species diversity and biomass of 25–27 species/m² and 956.76–1165.35 g/m², respectively. The constructive species suddenly change in the 24th year, and the population of S. grandis increases rapidly to 21 m^?2 accounting for 25% of the total plant population. Long‐term enclosure leads to decreased species diversity and biomass and is not beneficial for grassland renewing. The species diversity and biomass of degraded grassland continuously decrease to 10 species/m² and 392.1 g/m² due to long‐term artificial failure and transitionally grazing, leading to harden soil with slow rainfall infiltration, where plants can only sustain life under the drought condition. Therefore, reasonable cutting and rotational grazing are the methods of choice for the gradual increase of species diversity and promotion of the natural renewal and forward succession of the grassland on Loess Plateau. These results provide reliable information for the diversity dynamic change as better indictors of soil quality and sustainable utilization mode.  相似文献   

An evaluation of the universal soil loss equation and field techniques for assessing soil erosion on a tropical alfisol in western Nigeria     

P. W. Mtakwa  R. Lal  R. B. Sharma 《水文研究》1987,1(2):199-209

Four techniques for soil erosion assessment were compared over two consecutive seasons for bare-fallow plots and a maize-cowpea sequence in 1985 at IITA, Ibadan, Nigeria. The techniques used were: tracer (aluminium paint), nails (16 and 25), the rill method, and the Universal Soil Loss Equation (USLE). Soil loss estimated by these techniques was compared with that determined using the runoff plot technique. There was significantly more soil loss (P < 0·01) in bare-fallow than in plots under maize (Zea mays) or cowpea (Vigna unguiculata). In the first season, soil loss from plots sown to maize was 40·2 Mg ha^?1 compared with 153·3 Mg ha^?1 from bare-fallow plots. In the second season, bare-fallow plots lost 87·5 Mg ha^?1 against 39·4 Mg ha^?1 lost from plots growing cowpea. The techniques used for assessing erosion had no influence on the magnitude of soil erosion and did not interfere with the processes of erosion. There was no significant difference (P < 0·05) between soil erosion determined by the nails and the runoff plot technique. Soil loss determined on six plots (three under maize, three bare-fallow) by the rill technique, at the end of the season, was significantly lower (P < 0·05) than that determined by the runoff plot technique. The soil loss estimated by the rill method was 143·2, 108·8 and 121·9 Mg ha^?1 for 11, 11, and 8 per cent slopes respectively, in comparison with 201·5, 162·0, and 166·4 Mg ha^?1 measured by the runoff plot method. Soil loss measured on three bare-fallow plots on 10 different dates by the rill technique was also significantly lower (P < 0·01) than that measured by the runoff plot. In the first season the USLE significantly underestimated soil loss. On 11, 11, and 8 per cent slopes, respectively, soil loss determined by the USLE was 77, 92, and 63 per cent of that measured by the runoff plot. However, in the second season there was no significant difference between soil loss determined by the USLE and that determined by the conventional runoff plot technique.  相似文献   

Assessing the role of forests in mitigating eutrophication downstream of pasture during spring snowmelt          下载免费PDF全文

Masaaki Chiwa  Sachiko Inoue  Naoaki Tashiro  Daisuke Ohgi  Yoshitoshi Uehara  Hideaki Shibata  Atsushi Kume 《水文研究》2015,29(4):615-623

Little research has examined whether forests reduce stream water eutrophication in agricultural areas during spring snowmelt periods. This study evaluated the role of forests in ameliorating deteriorated stream water quality in agricultural areas, including pasture, during snowmelt periods. Temporal variation in stream water quality at a mixed land‐use basin (565 ha: pasture 13%, forestry 87%), northern Japan, was monitored for 7 years. Synoptic stream water sampling was also conducted at 16 sites across a wide range of forest and agricultural areas in a basin (18.3 km²) in spring, summer and fall. Atmospheric nitrogen (N) and phosphorus (P) deposition were measured for 4 years. The results showed that concentration pulses of nitrate, organic N and total P in stream water were observed when discharge increased during spring snowmelt. Their concentrations were high when silicate concentrations were low, suggesting surface water exported from pasture largely contributed to stream water pollution during snowmelt. Atmospheric N and P deposition (4.1 kg N ha^?1 y^?1; 0.09 kg P ha^?1 y^?1, respectively) was too low to affect the background concentrations of N and P in streams from forested areas. Reduction of eutrophication caused by nutrients from pasture was mainly due to dilution by water containing low concentrations of N and P exported from forested areas, whereas in‐stream reduction was not a dominant process. Results indicate that forests have a limited capacity to reduce the concentration pulses of N and P in stream water during snowmelt in this study basin. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Some observations on the chemical weathering of the Dartmoor granite     

Andrew G. Williams  Les Ternan  Martin Kent 《地球表面变化过程与地形》1986,11(5):557-574

The majority of geomorphological papers about Dartmoor have been essentially speculative, particularly when discussing weathering processes and the evolution of the Dartmoor landscape. In contrast, this article presents a synthesis of several experimental investigations aimed at studying the chemical weathering of Dartmoor granite through the systematic analysis of soil and water samples. This involved the computation of a geochemical budget to determine the amount of erosion in the catchment, as well as more detailed mineralogical investigations within a soil profile. The annual output of solutes due to weathering was 116 kg ha^?1 a^?1 of which the majority was silica (93 kg ha^?1 a^?1). From an examination of the soil mineralogy, it was calculated that these solutes were derived from the dissolution of approximately 200 kg ha^?1 a^?1 plagioclase, 90 kg ha^?1 a^?1 biotite, and 40 kg ha^?1 a^?1 orthoclase. As well as the weathering of granite, there was also the production of kaolinite (150 kg ha^?1 a^?1) and gibbsite (0.02 kg ha^?1 a^?1). Analysis of the soil water chemistry confirmed that kaolinite was the stable mineral phase in the regolith, although in areas where interflow was the dominant mode of water movement, the solute composition was in equilibrium with both kaolinite and gibbsite. Examination of the clay mineralogy confirmed these results. The microtexture of quartz grains was examined by the scanning electron microscope as another means of investigating the hydrochemical environment in the soil. Silica was found precipitated on all the grains examined but the maximum amount occurred in the Bs horizon. This evidence showed that, firstly, the dissolution of aluminosilicate minerals is greater than that calculated by the chemical budget and, secondly, that models of granite weathering must take localized weathering in the soil profile into account. The final part of the paper highlights the limitations of calculating denudation rates for an entire catchment and stresses the need to consider weathering as a highly localized phenomenon, particularly where there are high volumes of interflow at hill crest sites. Observations on granite decomposition in the future should be quantitative in approach and be related to the local site conditions.  相似文献   

Developing a sediment budget for a small drainage basin in Australia     

R. J. Loughran  B. L. Campbell  D. J. Shelly  G. L. Elliott 《水文研究》1992,6(2):145-158

A sediment budget was developed for the 1.7 km² Maluna Creek drainage basin located in the Hunter Valley, New South Wales, Australia, for the period 1971-86. the impact of viticulture, which commenced at Maluna in 1971, was studied using erosion plots, with caesium-137 as an indicator of both soil erosion and sedimentation. Two methods were used to estimate vineyard soil losses from caesium-137 measurements. Sediment output from the catchment was measured for three years, and extrapolated from readings taken at a nearby long-term stream flow gauging station for the remaining 13 years. Relative amounts of soil loss from forest (60 per cent basin area), grazing land (30 per cent) and vineyards (10 per cent) were calculated. Soil losses by rain splash detachment were ten times greater from bare/cultivated sufaces than from the forest. Erosion plots of area 2 m² showed no significant differences in soil loss between forest and grassland but, under bare soil, losses were 100 times greater. the ¹³⁷Cs method was employed to calculate net soil loss from all vineyard blocks using both a previously established calibration curve and a proportional model. the latter method gave estimates of soil loss which were 3-9 times greater than by the calibration curve, and indicated that average soil losses from the vineyard were equivalent to 62 t ha^?1 y^?1 (1971-86). It was estimated that the forest contributed 1-8 per cent, the grazing land 1.6 per cent, and the vineyard 96.6 per cent of the total soil loss during that period. Sediment storages within the fluvial system adjacent to the vineyard ws 9460 t for the period, whereas sediment output was equivalent to 215 t km^?1 y^?1. Independent measurements of soil erosion, storage, and output showed that 56 per cent of the eroded sediment remained in the catchment, and 34 per cent was transported out by Maluna Creek. the budget was able to be balanced to within 10 per cent.  相似文献   

Piping dynamics in mid‐altitude mountains under a temperate climate: Bieszczady Mountains,eastern Carpathians          下载免费PDF全文

Anita Bernatek‐Jakiel  Michał Jakiel  Kazimierz Krzemień 《地球表面变化过程与地形》2017,42(9):1419-1433

Piping has been recognized as an important geomorphic, soil erosion and hydrologic process. It seems that it is far more widespread than it has often been supposed. However, our knowledge about piping dynamics and its quantification currently relies on a limited number of data for mainly loess‐derived areas and marl badlands. Therefore, this research aimed to recognize piping dynamics in mid‐altitude mountains under a temperate climate, where piping occurs in Cambisols, not previously considered as piping‐prone soils. It has been expressed by the estimation of erosion rates due to piping and elongation of pipes in the Bere?nica Wy?na catchment in the Bieszczady Mountains, eastern Carpathians (305 ha, 188 collapsed pipes). The research was based on the monitoring of selected piping systems (1971–1974, 2013–2016). Changes in soil loss vary significantly between different years (up to 27.36 t ha^?1 yr^?1), as well as between the mean short‐term erosion rate (up to 13.10 t ha^?1 yr^?1), and the long‐term (45 years) mean of 1.34 t ha^?1 yr^?1. The elongation of pipes also differs, from no changes to 36 m during one year. The mean total soil loss is 48.8 t ha^?1 in plots, whereas in the whole studied catchment it is 2.0 t ha^?1. Hence, piping is both spatially and temporally dependent. The magnitude of piping in the study area is at least three orders of magnitude higher than surface erosion rates (i.e. sheet and rill erosion) under similar land use (grasslands), and it is comparable to the magnitude of surface soil erosion on arable lands. It means that piping constitutes a significant environmental problem and, wherever it occurs, it is an important, or even the main, sediment source. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Towards constraining the magnitude of global agricultural sediment and soil organic carbon fluxes     

Sebastian Doetterl  Kristof Van Oost  Johan Six 《地球表面变化过程与地形》2012,37(6):642-655

Reliable quantitative data on the extent and rates of soil erosion are needed to understand the global significance of soil‐erosion induced carbon exchange and to underpin the development of science‐based mitigation strategies, but large uncertainties remain. Existing estimates of agricultural soil and soil organic carbon (SOC) erosion are very divergent and span two orders of magnitude. The main objective of this study was to test the assumptions underlying existing assessments and to reduce the uncertainty associated with global estimates of agricultural soil and SOC erosion. We parameterized a simplified erosion model driven by coarse global databases using an empirical database that covers the conterminous USA. The good agreement between our model results and empirical estimates indicate that the approach presented here captures the essence of agricultural erosion at the scales of continents and that it may be used to predict the significance of erosion for the global carbon cycle and its impact on soil functions. We obtained a global soil erosion rate of 10.5 Mg ha^‐1 y^‐1 for cropland and 1.7 Mg ha^‐1 y^‐1 for pastures. This corresponds to SOC erosion rates of 193 kg C ha^‐1 y^‐1 for cropland and 40.4 kg C ha^‐1 y^‐1 for eroding pastures and results in a global flux of 20.5 (±10.3) Pg y^‐1 of soil and 403.5 (±201.8) Tg C y^‐1. Although it is difficult to accurately assess the uncertainty associated with our estimates of global agricultural erosion, mainly due to the lack of model testing in (sub‐)tropical regions, our estimates are significantly lower than former assessments based on the extrapolation of plot experiments or global application of erosion models. Our approach has the potential to quantify the rate and spatial signature of the erosion‐induced disturbance at continental and global scales: by linking our model with a global soil profile database, we estimated soil profile modifications induced by agriculture. This showed that erosion‐induced changes in topsoil SOC content are significant at a global scale (an average SOC loss of 22% in 50 years) and agricultural soils should therefore be considered as dynamic systems that can change rapidly. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

三峡水库消落区典型草本植物氮、磷养分计量特征     

米玮洁  邹怡  李明  陈明秀  董方勇 《湖泊科学》2016,28(4):802-811

为明确消落区土壤养分对植物生长的影响,通过室内栽培试验,研究三峡库区秭归消落区土壤3种氮磷水平下4种草本植物—鬼针草(Bidens pilosa)、苍耳(Xanthium sibiricum)、水蓼(Polygonum hydropiper)、藜(Chenopodium album)长势及氮、磷计量特征.结果表明,消落区土壤中生长的植物氮含量为7.98~19.4 mg/g,磷含量为0.740~3.880 mg/g,氮磷比为3.48~13.70,判别植物生长受氮限制.外源氮磷的添加促进植物氮、磷含量明显升高,但氮磷比没有明显变化;外源氮磷添加解除植物受氮的限制作用.4种植物对消落区土壤低氮环境具有一定的适应能力.比较消落区土壤中4种植物长势,鬼针草生物量、相对生长率、根茎生物量比最高,氮磷养分丰富对鬼针草生长促进作用最明显,表明鬼针草更易于在氮、磷贫乏的三峡库区消落区形成优势群落.  相似文献   

Changes associated with Phragmites australis invasion in plant community and soil properties: A study on three invaded communities in a wetland,Victoria, Australia     

《Limnologica》2017

Phragmites australis invasion is altering plant communities and therefore, soil properties have been changed significantly. This study compared the diversity among three communities in a wetland to assess the impact of invasion by Phragmites and the associated impact on soil properties. Three diversity indices, species richness (S), evenness (E) and Shanon-Weiner index (H) had significantly higher values in uninvaded plots compared to invaded in all the communities. Invaded plots had the lowest diversity, with H = 0 and Simpson’s index (D) = 1, (i.e. they were monospecific). These results support the idea that a reduction in diversity can be expected in wetlands colonized by Phragmites. Phragmites invasion significantly increased soil moisture, EC, phenolics, organic carbon, dehydrogenase activity and microbial biomass (C, N, P) with reduction of pH and arbuscular mycorrhizae fungi spore density compared with uninvaded zones. In addition, the study of antifungal phytochemistry of Phragmites elucidated the decrease of the competitive abilities of native plant Melaleuca ericifolia by interfering with formation of mycorrhizal associations and biomass. Our results suggest that Phragmites invasion has caused significant ecological alterations in communities by demonstrating a combined effect to plant diversity and soil variables.  相似文献   

Effects of plant roots on the soil erosion rate under simulated rainfall with high kinetic energy     

Yoshinori Shinohara  Sohei Otani  Tetsuya Kubota  Kyoichi Otsuki  Kazuki Nanko 《水文科学杂志》2013,58(13):2435-2442

ABSTRACT

This study examined the effects of herbaceous plant roots on interrill erosion using two herbaceous species: clover (Trifolium repens) and oats (Avena sativa). We developed a simple rainfall simulator with relatively high normalized kinetic energy (KE; 23.2 J m^?2 mm^?1). Under simulated rainfall, we measured eroded soil for 42 boxes with various amounts of aboveground and belowground biomass. Aboveground vegetation had a significant effect on the soil erosion rate (SER). We found a clear negative relationship between the percent vegetation cover (c) and the SER. In contrast, plant roots showed no effects on the SER. The SER was not significantly different between the boxes with and without plant roots under similar c conditions. Thus, plant roots could have less of an effect on the SER under higher KE conditions.