Soil Erosion in Mesic Forests: How do Biological Soil Crusts affect sediment transport and surface runoff?

2020 ◽  
Author(s):  
Corinna Gall ◽  
Martin Nebel ◽  
Dietmar Quandt ◽  
Michael Sauer ◽  
Thomas Scholten ◽  
...  
Keyword(s):  
Soil Erosion ◽  
Surface Runoff ◽  
Dna Analysis ◽  
Soil Layer ◽  
Soil Surface ◽  
Biological Soil Crusts ◽  
Small Scale ◽  
Sediment Discharge ◽  
Soil Crusts ◽  
Disturbed Areas

<p>Soil erosion under forests occurs if forest layers get disturbed. Disturbances may arise from treefall, forest road works, skid trails or deforestation. In these disturbed areas, both an intact canopy and forest floor cover are missing, so that forest soils lack protection against water erosion. To counteract these negative effects a quick restoration of soil surface covers by vegetation is important. In particular, biological soil crusts (biocrusts) are able to quickly colonize gaps in higher vegetation and they are known to reduce soil erodibility. So far, the focus of biocrust research has been in drylands, whereas biocrusts have proven to be an important factor in mesic environments, especially as a pioneer vegetation in disturbed areas.</p><p>In this study, the natural succession of biocrusts in skid trails was observed on four different underlying substrates in a temperate European forest ecosystem (Schönbuch Nature Park in the state of Baden-Württemberg, Germany) and their influence on surface runoff, sediment discharge and nutrient relocation was investigated. Therefore, 144 micro-scale runoff plots (ROPs, 40 x 40 cm) were established with four replicates in the wheel tracks as well as in the center tracks and two replicates on undisturbed forest soil. In order to initiate splash and interrill erosion, four rainfall simulations were carried out from spring to winter with a constant intensity of 45 mm h<sup>-1</sup>. With the purpose to compare these small-scale erosion rates with a larger scale, additional turbidity sensors were installed in the catchment area. The biocrust succession was determined by regular vegetation surveys with a classification of mainly mosses and liverworts up to the species level. Additionally, DNA samples of the upper soil layer were collected to conduct DNA extractions specify other potential biocrust organisms such as lichens, cyanobacteria, fungi and algae.</p><p>First results show that surface runoff and sediment discharge are higher in the wheel track than in the center track and that both parameters are reduced with a higher developmental stage of soil surface cover. The vegetation survey demonstrates a quick development of moss-dominated biocrusts from April to October with up to ten different species in one ROP. Depending on the location of the skid trail, a quick development of the higher vegetation was observed as well. Lab work on nutrient relocation and DNA analysis is still in progress and further results will be presented at the EGU 2020.</p>

Plot-scale wash-off of Cesium-137 and Strontium-90 after three decades since the Chernobyl accident

2020 ◽  
Author(s):  
Yoshifumi Wakiyama ◽  
Yasunori Igarashi ◽  
Yuichi Onda ◽  
Dmitry Samoilov ◽  
Hlib Lisovy ◽  
...  
Keyword(s):  
Surface Runoff ◽  
Soil Surface ◽  
Water Repellency ◽  
Sediment Discharge ◽  
Exclusion Zone ◽  
Runoff Water ◽  
Wild Fire ◽  
Strontium 90 ◽  
Cesium 137 ◽  
Level Sensor

<p>Long-term behaviors of Cesium-137 (<sup>137</sup>Cs) and Strontium-90 (<sup>90</sup>Sr) have been of great interest in Chernobyl and its downstream area. This study presents plot-scale observations of <sup>137</sup>Cs and <sup>90</sup>Sr wash-off in the Chernobyl exclusion zone since 2018 to date. Runoff plots were established on a pine forest in the Kopachi area (PF-KP), an abandoned farmland in the Korogod area (AF-KR) and a post wild fire territory in the Red Forest (WF-RF) in December 2017. Each runoff plot consists of eroding surface of 22.13 m length and 5 m width, a 30° V-notch weir with water level sensor for monitoring surface runoff and tanks for collecting runoff water and sediments. Since February 2018, runoff water and sediment samples trapped in the weir and tanks have been collected after rainfall events and analyzed for particulate <sup>137</sup>Cs concentration, dissolved <sup>137</sup>Cs concentration, and dissolved <sup>90</sup>Sr concentration. Analyses of samples in 2, 4, and 3 wash-off events were completed for PF-KP, AF-KR, and WF-RF, respectively. The ash/litter on soil surface, soil of 0-1 cm depth, soil of 1-2 cm depth, and soil of 2-3 cm depth were sampled with a scraper plate and subject to measurements of <sup>137</sup>Cs and <sup>90</sup>Sr concentrations.  Total volume of surface runoff from PF-KP, AF-KR, and WF-RF were 0.97, 0.73, and 3.2 mm, respectively. Total sediment discharge from PF-KP, AF-KR, and WF-RF were 0.29, 0.015, 1.7 g m<sup>-2</sup>, respectively. The runoff and sediment discharge from PF-KP and WF-RF were mainly observed in summer and attributed to severe water repellency of the surface soils. Total particulate <sup>137</sup>Cs wash-off from PF-KP, AF-KR, and WF-RF were 51, 0.082, 270 Bq m<sup>-2</sup>, respectively. Total dissolved <sup>137</sup>Cs wash-off from PF-KP, AF-KR, and WF-RF were 7.4, 0.024, 9.8 Bq m<sup>-2</sup>, respectively. Total dissolved <sup>90</sup>Sr wash-off from PF-KP, AF-KR, and WF-RF were 55, 0.31, 230 Bq m<sup>-2</sup>, respectively.  These results indicate that wild fire enhances surface runoff and sediment yield and result in greater wash-off of <sup>137</sup>Cs and <sup>90</sup>Sr. In comparisons between PF-KP and WF-RF, apparent Kd value for <sup>137</sup>Cs at WF-RF was higher than at PF-KP. Ratio of dissolved <sup>137</sup>Cs and <sup>90</sup>Sr concentration to those in ash/litter layer at PF-KP was lower than those of WF-RF. The dissolution of these radionuclides into runoff water appeared to be restrained in the post wild-fire site.</p>

Biological soil crusts greatly contribute to small-scale soil heterogeneity along a grazing gradient

2013 ◽  
Vol 64 ◽  
pp. 28-36 ◽  
Author(s):  
L. Concostrina-Zubiri ◽  
E. Huber-Sannwald ◽  
I. Martínez ◽  
J.L. Flores Flores ◽  
A. Escudero
Keyword(s):  
Soil Heterogeneity ◽  
Biological Soil Crusts ◽  
Small Scale ◽  
Soil Crusts ◽  
Small Scale Soil

Natural terrace formation through vegetative barriers on hillside farms in Honduras

1998 ◽  
Vol 13 (2) ◽  
pp. 79-82 ◽  
Author(s):  
Robert J. Walle ◽  
Brian G. Sims
Keyword(s):  
Soil Erosion ◽  
Crop Yields ◽  
Fertility Restoration ◽  
Soil Surface ◽  
Small Scale ◽  
South Central ◽  
The Difference ◽  
Small Scale Farmers ◽  
And Control ◽  
Soil Accumulation

AbstractThe effects of contour live barriers of vetiver and pennisetum on soil erosion were studied on four small farms in south central Honduras. Paired plots were installed and soil erosion measured by changes in the soil surface level of transects 0.3 and 6.0 m up the slope from the barrier. After three years, transects 0.3 m above the barriers significantly retained eroded soil compared with control transects. Soil accumulation by barriers ranged from 2.6 to 11.2 cm, and natural terrace formation (the difference between the barrier and corresponding control transect) ranged from 5.2 to 13.8 cm. No difference was detected between barrier and control for the transects 6.0 m above the barrier. Deposition in front of the barriers and reduction in surface rilling were apparent to farmers. Erosion from up slope on the barrier plots and from both transects in the control sections was not obvious. Direct measurement and farmer observation of sediment deposition by live barriers will help evaluate farmer-identified species for future use. The deposition helps farmers become aware of sheet erosion before the effects of soil degradation on crop yields become grossly apparent and soil fertility restoration becomes too costly for small-scale farmers.

scholarly journals Quantifying Mechanistic Detachment Parameters Due to Humic Acids in Biological Soil Crusts

Land ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1180
Author(s):  
Atheer A. Abbood ◽  
Abdul-Sahib T. Al-Madhhachi
Keyword(s):  
Electrical Conductivity ◽  
Organic Matter ◽  
Humic Acid ◽  
Biological Soil Crusts ◽  
Exchange Capacity ◽  
Scale Model ◽  
Small Scale ◽  
Soil Erodibility ◽  
Soil Crusts ◽  
Detachment Rate

Humic acid (HA) is a material that could be used to decrease erosion and improve soil structure. It is also known that biological soil crusts (biocrusts) have a major role in soil stabilization, but the mechanism is not well understood in the presence of HA, especially with mechanistic soil detachment rate parameters (b0 and b1) of the Wilson model, where b0 is the dimensional soil detachment parameter and b1 is the dimensional soil threshold parameter. Therefore, this study intends to (1) investigate the effect of different humic acid (HA) concentrations (0%, 4%, and 8%) on mechanistic soil detachment rate parameters (b0 and b1,) in the Tigris Riversides of the Gheraiat region, Baghdad City, Iraq, of the crusted versus uncrusted soils using a small scale model of the jet erosion tests (mini-JET) at different curing periods (1 week, 2 weeks, and 3 weeks), and (2) examine the impact of HA on b0 and b1 parameters versus some soil characteristics, such as electrical conductivity, cation exchange capacity, and soil organic matter for uncrusted and crusted soils. Thirty-six undisturbed soil specimens (18 for crusted soils and 18 for uncrusted soils) were acquired from the Tigris Riverbank. On these specimens, the mini-JET was used to determine the mechanistic cohesive soil erodibility parameters b0 and b1. The results showed that the value of b0 decreased up to 60% with an increase in curing times for crusted soils until they reached their optimum values at 2 weeks. There was no consistent pattern for b1 at different curing times. As the concentration of HA increased, the value of b0 decreased up to 86% and 99% for crusted and uncrusted soils, respectively. HA significantly improved electrical conductivity, exchange capacity, and organic matter in the soil and reduced soil erodibility. This study provides the benefits of adding HA to the soils as a soil stabilizer using a low-cost technique, which is the JET instrument.

An experiment to assess the influence of urban pavements on biocide leaching from facades into urban soil and groundwater

2020 ◽  
Author(s):  
Felicia Linke ◽  
Jens Lange
Keyword(s):  
Solute Transport ◽  
Urban Environment ◽  
Soil Layer ◽  
Soil Surface ◽  
Urban Groundwater ◽  
Field Capacity ◽  
Transformation Products ◽  
Small Scale ◽  
Rain Event ◽  
Building Facades

<p>Biocides added to facade renders and paints prevent algae and fungi growing at conventional buildings. During rain events biocides leach from facades into the urban environment and its compartments i.e. soil, surface water and groundwater. In many cases polluted façade runoff reaches partly sealed pavements and a major part infiltrates. Transport and transformation processes of biocides below these pavements are largely unknown. It may be hypothesized that concentrated infiltration in joints surrounding paving stones may enhance water percolation and accelerate solute transport. This would mean that partly sealed pavements beneath building facades are hotspots for the entry of biocides into groundwater. This study aims at testing this hypothesis using an experimental mass balance approach.</p><p><br>Five weighable lysimeters in freestanding boxes represent a small-scale section of an urban environment. Three lysimeter have a sealed or partly sealed plaster surface (concrete stones, granite stones with sand joints, and grass paver). The other two lysimeter represent unsealed surfaces, one of them contains a 10cm soil layer with grass cover. The fifth lysimeter acts as a control and has a 40cm layer of filter gravel. Below all surface layers there is 20cm of crushed sand and 10cm of filter gravel. This setup follows typical guidelines of urban construction.</p><p><br>A hose with holes represents the linear leachate of a façade during a rain event. In pre-tests isotopically depleted (collected snowmelt) and enriched (spiked with a heavy standard) water serves to illustrate differences between areal and linear infiltration. Then Terbutryn dissolved in water acts as the main contaminant. It is a biocidal ingredient of a variety of paints and renders. Additional tracers such as bromide, uranine and sulforhodamine B help to illustrate the solute transport inside the lysimeters. Brilliant blue is used to visualize infiltration patterns.</p><p><br>For the experiment the boxes are saturated to field capacity. Pulses of the Terbutryn and tracer solution are poured on the gutter to represent a series of rainfall events with façade leaching. The entire percolate is collected at the bottom of the lysimeter and water samples are taken at regular intervals. After the experiment, the lysimeter matrices are sampled for Terbutryn, three prominent transformation products and for the different tracers. In parallel, physico-chemical soil properties are assessed. This experiment will provide new insights into processes that promote biocide leaching from building facades into urban groundwater.</p>

scholarly journals Eco-physiological characterization of early successional biological soil crusts in heavily human impacted areas – Implications for conservation and succession

2017 ◽  
Author(s):  
Michelle Szyja ◽  
Burkhard Büdel ◽  
Claudia Colesie
Keyword(s):  
Carbon Fixation ◽  
Climatic Factors ◽  
Biological Soil Crusts ◽  
Taxonomic Composition ◽  
Nostoc Commune ◽  
Fixation Rate ◽  
Physiological Characterization ◽  
Soil Crusts ◽  
Disturbed Areas

Abstract. Eco-physiological characterization of photoautotrophic communities is not only necessary to identify the response of carbon fixation related to different climatic factors, but also to evaluate risks connected to changing environments. In biological soil crusts (BSCs), the description of eco-physiological features is difficult, due to the high variability in taxonomic composition and variable methodologies applied. Especially for BSCs in early successional stages, the available datasets are rare or focused on individual constituents, although these crusts may represent the only photoautotrophic component in many heavily disturbed ruderal areas, like parking lots or building areas with increasing surface area worldwide. We analyzed the response of photosynthesis and respiration to changing BSC water contents, temperature and light in two early successional BSCs. One BSC was dominated by the cyanobacterium Nostoc commune, the other by the green alga Zygogonium ericetorum. Independent of species composition, both crust types had convergent features like high light acclimatization and low or no depression in carbon uptake at water suprasaturation. This particular setup of eco-physiological features may enable these communities to cope with a high variety of climatic stresses, and may therefore be a reason for their success in heavily disturbed areas with ongoing human impact. Nevertheless, a major divergence between the two BSCs was their absolute carbon fixation rate on a chlorophyll basis, which was significantly higher for the cyanobacterial crust. This study emphasizes the importance of measuring intact BSCs under natural conditions for collecting reliable data.

On the effect of different moss species on soil erosion, percolation and carbon relocation

2021 ◽  
Author(s):  
Corinna Gall ◽  
Lena Grabherr ◽  
Martin Nebel ◽  
Thomas Scholten ◽  
Sonja M. Thielen ◽  
...  
Keyword(s):  
Soil Erosion ◽  
Surface Runoff ◽  
Biological Soil Crust ◽  
Bare Soil ◽  
Individual Species ◽  
Sediment Discharge ◽  
Moss Species ◽  
Moss Cover ◽  
The Impact ◽  
Soil Substrates

<p>For decades, soil erosion has been a major environmental problem as it degrades the most productive soil layers, which threatens, among other things, food production worldwide. Although these effects have been known for a long time, there are still a variety of challenges to mitigating soil erosion in different ecosystems. As climate change progresses, the risk of soil loss increases, making the preparation of effective solutions very urgent. A current research focus is on the restoration of a protective soil cover following disturbances in the vegetation layer, e.g., through the reestablishment of biological soil crust communities. These are often dominated by bryophytes in humid climates. So far, several studies examined the general protective influence of bryophytes against soil erosion, however only few of them addressed how individual species affect specific erosion processes in detail.</p><p>To fill this research gap we investigated the impact of six moss species on soil erosion, percolation and carbon relocation by means of rainfall simulations. Therefore, we used topsoil substrate from four sites in the Schönbuch Nature Park in South Germany which covers different kinds of bedrock and varying soil texture and pH. Subsequently, they were sieved by 6.3 mm and filled into metal infiltration boxes (40 x 30 cm) up to a height of 6.5 cm. The moss species differ in origin (either collected in the field or cultivated in the lab) as well as growth form (pleurocarpous or acrocarpous). Rainfall simulations were performed for bare soil substrates, as well as for moss-covered soil substrates six months later and both in dry and wet conditions. Additionally, we conducted rainfall simulations with leaf and coniferous litter on bare soil substrates. During the simulations we monitored soil moisture in two position - 3 cm depth plus soil surface - with biocrust wetness probes (BWP) and quantified surface runoff, percolation and sediment discharge. Afterwards we determined carbon contents of the sediment and dissolved organic carbon in the liquid phase of runoff and percolated water.</p><p>While surface runoff was increased by 5% due to the litter cover compared to the bare soil substrate, sediment discharge decreased to 97%. Runoff rates could also be mitigated by 90 % as a result of the moss cover. Furthermore, due to the dense moss cover sediment rates were almost reduced to zero. Preliminary results show that there are differences between the moss species in terms of sediment discharge, but not in context with runoff. The analyses of carbon contents in surface runoff and the percolated water are still in progress, as is the evaluation of the BWP measurements. These outcomes will be presented at vEGU21.</p>

Biological soil crusts mediate changes in soil aggregate stability along a climate gradient in Chile

2021 ◽  
Author(s):  
Nicolás Riveras Muñoz ◽  
Steffen Seitz ◽  
Corinna Gall ◽  
Hugo Pérez ◽  
Peter Kuehn ◽  
...  
Keyword(s):  
Geometric Mean ◽  
Aggregate Stability ◽  
Soil Surface ◽  
Soil Aggregate ◽  
Biological Soil Crusts ◽  
Soil Aggregate Stability ◽  
Climate Gradient ◽  
Soil Crusts ◽  
Stabilizing Effect ◽  
The Stability

<p>Biological soil crusts (biocrusts) composed of cyanobacteria, algae, lichens and bryophytes have a stabilizing effect on the soil surface. This effect is mostly studied in arid climates, where biocrusts are the main biological agent to steady and bind together soil aggregates. Nevertheless, biocrusts are also an integral part of the soil surface under semi-humid and humid climate conditions, mainly covering open spaces in forests and on fallow lands. As such, they often develop after vegetation disturbances, when their ability to compete with higher plants is increased. To better understand how biocrusts mediate changes in soil aggregate stability under different climatic conditions, we analyzed soil substrates taken under biocrust communities from four national parks in Chile using dry and wet sieving. These samples cover soils from a large climate gradient from arid (Pan de Azúcar), semiarid (Santa Gracia), mediterranean (La Campana) to humid (Nahuelbuta). <br>Biocrust communities were dominated by cyanobacteria in Pan de Azúcar and Santa Gracia, bryophytes and lichens in La Campana and bryophytes in Nahuelbuta. They showed a stabilizing effect on the soil surface in three of the four investigated climates. Their presence increased the Mean Weight Diameter of the aggregates (MWD) by 102% in Pan de Azúcar, 208% in Santa Gracia and 82% in La Campana. In Nahuelbuta there was no significant increase to the condition without biocrust, because the abundance of permanent soil covering higher vegetation does not allow the effect of biocrusts to manifest. The stabilization differed between the aggregate fractions studied, being most pronounced for smaller aggregates >2 mm. The Geometric Mean Diameter (GMD) showed similar results as MWD, but with a clear effect of drying and wetting conditions, as an increase in the stability directly related to precipitation and the climatic gradient. Bulk density (BD) changed from high mean values of 1.50 g cm<sup>-3</sup> in Pan de Azúcar and 1.63 g cm<sup>-3</sup> in Santa Gracia (where cattle grazing was observed) to 1.16 g cm<sup>-3</sup> in La Campana and the lowest mean of 0.62 g cm<sup>-3</sup> in Nahuelbuta, where we observed a more developed soil structure and high organic matter content (21.58% in average). Accordingly, here we also found pronounced hydrophobicity of the soil. These preliminary findings indicate not only differences in the stability of the aggregates, but also in the state of conservation and management of the soils. Results will now be extended by further statistical analyses, which will additionally be presented at vEGU21.</p>

scholarly journals Understory Limits Surface Runoff and Soil Loss in Teak Tree Plantations of Northern Lao PDR

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2327 ◽  
Author(s):  
Layheang Song ◽  
Laurie Boithias ◽  
Oloth Sengtaheuanghoung ◽  
Chantha Oeurng ◽  
Christian Valentin ◽  
...  
Keyword(s):  
Soil Erosion ◽  
Surface Runoff ◽  
Soil Loss ◽  
Management Practices ◽  
Lao Pdr ◽  
Soil Surface ◽  
Tree Plantations ◽  
Runoff Coefficient ◽  
Teak Tree ◽  
Runoff And Soil Loss

Many mountainous regions of the humid tropics experience serious soil erosion following rapid changes in land use. In northern Lao People’s Democratic Republic (PDR), the replacement of traditional crops by tree plantations, such as teak trees, has led to a dramatic increase in floods and soil loss and to the degradation of basic soil ecosystem services such as water filtration by soil, fertility maintenance, etc. In this study, we hypothesized that conserving understory under teak trees would protect soil, limit surface runoff, and help reduce soil erosion. Using 1 m2 microplots installed in four teak tree plantations in northern Lao PDR over the rainy season of 2017, this study aimed to: (1) assess the effects on surface runoff and soil loss of four understory management practices, namely teak with no understory (TNU; control treatment), teak with low density of understory (TLU), teak with high density of understory (THU), and teak with broom grass, Thysanolaena latifolia (TBG); (2) suggest soil erosion mitigation management practices; and (3) identify a field visual indicator allowing a rapid appraisal of soil erosion intensity. We monitored surface runoff and soil loss, and measured teak tree and understory characteristics (height and percentage of cover) and soil surface features. We estimated the relationships among these variables through statistics and regression analyses. THU and TBG had the smallest runoff coefficient (23% for both) and soil loss (465 and 381 g·m−2, respectively). The runoff coefficient and soil loss in TLU were 35% and 1115 g·m−2, respectively. TNU had the highest runoff coefficient and soil loss (60%, 5455 g·m−2) associated to the highest crusting rate (82%). Hence, the soil loss in TBG was 14-times less than in TNU and teak tree plantation owners could divide soil loss by 14 by keeping understory, such as broom grass, within teak tree plantations. Indeed, a high runoff coefficient and soil loss in TNU was explained by the kinetic energy of rain drops falling from the broad leaves of the tall teak trees down to bare soil, devoid of plant residues, thus leading to severe soil surface crusting and soil detachment. The areal percentage of pedestal features was a reliable indicator of soil erosion intensity. Overall, promoting understory, such as broom grass, in teak tree plantations would: (1) limit surface runoff and improve soil infiltrability, thus increase soil water stock available for both root absorption and groundwater recharge; and (2) mitigate soil loss while favoring soil fertility conservation.

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