High Erosion Rates Research Articles

Tendency of soil erosion dynamics by coupling radioisotopes and RUSLE model on the Southeastern Tibetan Plateau in response to climate warming and human activity

Soil erosion has created landscape problems in many parts of the world and in particular in cold regions where the sensitive permafrost conditions have changed due to climate warming. Such a case occurred in the Tibetan Plateau (TP), which has been strongly affected by global warming and human activities. Monitoring technologies, like remote sensing and field surveys were used to explore soil erosion rates in the TP, but they were limited by the resolution and meteorological disturbance factors or the spatial and time scales. Here, we present for the first time 210Pbex (excess lead-210) and 137Cs (caesium-137) data of soils from the southeastern TP (SETP) covering an area of 640,000 km2. In the permafrost-dominant areas, the results show mean soil-erosion rates in the last 56–100 years that were relatively higher (1891 t·km−2·a-1) based on 210Pbex than those based on 137Cs (1623 t·km−2·a-1). Modelling results from the Revised Universal Soil Loss Equation (RUSLE) indicate relatively high mean soil erosion rates of 4363 and 4394 t·km−2·a-1 using a period covering the last 40 or 10 years respectively. Our data suggest accelerating erosion rates on the SETP that are linked to permafrost degradation, and glacier and snow melting due to accelerating global climate warming. The increase in ground surface temperature of ∼2 °C in the last four decades has further shifted the regional hydrology, affecting the degeneration of vegetation cover and a further increase in soil-erosion rates. However, our radionuclides data also expose low erosion rates in the seasonally frozen ground at some sampling sites which indicates the complex nature of erosion trends in cold regions that require careful adaptation of soil management.

Sustainability Analysis of Soil Erosion Control in Rwanda: Case Study of the Sebeya Watershed

Soil erosion is a complex process that results in soil and fertility losses from agricultural land and, ultimately, leads to river sedimentation. This study aimed to assess various influential factors and processes affecting soil erosion and to recommend suitable site-based Soil Erosion Control Measures (SECM) for sustainable agriculture while minimizing the downstream rivers and reservoir sedimentation in the Sebeya watershed of Rwanda. The present research used a literature review, site visits, and focus groups to assess various SECM within the Sebeya watershed. As a result, various site-based SECM were evaluated, recommended, and simulated to alleviate high soil loss rates in the Sebeya watershed using the Universal Soil Erosion Equation (USLE) model. Simulating existing and proposed SECM, soil loss was reduced significantly from 73 t/ha/y to 29 t/ha/y. To highlight the implication of the site-based recommended SECM in improving agricultural productivity, this study suggests field investigations in soil erosion plots and prediction of crop yields from an established linear correlation model between soil loss and crop yields in the Sebeya watershed. For effective action in reducing high soil erosion rates to tolerable rates in the Sebeya watershed, the present research recommends implementing the site-based recommended SECM with mulching and drainage channels on the same farmland. However, lack of money and knowledge are the main limitations in implementing SECM in the Sebeya watershed. Therefore, governmental and non-governmental organizations should technically and financially help farmers in the Sebeya watershed.

The circular nutrient economy of terrestrial ecosystems and the consequences for rock weathering

Earth’s biosphere is thought to exert a substantial influence on regolith evolution and chemical weathering rates. However, ecosystems are also highly efficient at retaining and recycling nutrients. Thus, when the ecological demand for rock-derived nutrients (e.g., P, Ca, K) exceeds the rates of regolith supply, ecological retention and recycling strategies can minimize nutrient limitations. To evaluate the balance between nutrient recycling and new nutrient input, we combined a plant model that drives growth according to foliar P levels with a weathering model that includes regolith rejuvenation via erosion and export via chemical weathering according to water flow, regolith thickness, mineral dissolution rates, secondary minerals, and nutrient storage in organic and mineral phases. We find that plant growth is strongly dependent on the total regolith nutrient inventory, resulting in a strong correlation between plant productivity and erosion. Increased water export or decreased regolith thickness diminish the total inventory of nutrient corresponding to lower rates of recycling and lower plant growth. In contrast, purported biogenic drivers of weathering, such as enhanced mineral dissolution, only support higher growth rates at high erosion rates. At erosion rates typical of the global land surface, more rapid mineral dissolution combined with enhanced formation of secondary minerals, depletes the inventory of mineral P, resulting in no benefit for plant growth. We also find that the increased chemical weathering export does not scale directly with plant growth. For example, accelerated mineral weathering does increase chemical weathering export but not potential plant growth. Conversely, thicker regolith is associated with a small increase in weathering export, but a large increase in potential plant growth. Collectively, when plant growth is coupled to regolith weathering our calculations suggest that plant productivity is not directly correlated with silicate weathering fluxes, and that biotic drivers of silicate weathering may only be effective at high erosion rates not typical at the Earth’s surface.

Soil Constraints in an Arid Environment—Challenges, Prospects, and Implications

Climate models project that many terrestrial ecosystems will become drier over the course of this century, leading to a drastic increase in the global extent of arid soils. In order to decrease the effects of climate change on global food security, it is crucial to understand the arid environment and the constraints associated with arid soils. Although the effects of aridity on aboveground organisms have been studied extensively, our understanding of how it affects soil processes and nutrient cycling is lacking. One of the primary agricultural constraints, particularly in arid locations, is water scarcity, due to which arid soils are characterized by sparse vegetation cover, low soil organic carbon, poor soil structure, reduced soil biodiversity, and a high rate of soil erosion via wind. Increased aridity will limit the availability of essential plant nutrients and crop growth, and subsequently pose serious threats to key ecological processes and services. The increasing rate of soil salinization is another major environmental hazard that further limits the agricultural potential of arid soils. These soil constraints can be ameliorated and the crop yields increased through case-specific optimization of irrigation and drainage management, enhancing the native beneficial soil microbes, and combinations of soil amendments, conditioners, and residue management. This review explores technologies to ameliorate soil constraints and increase yields to maintain crop output in arid soils.

Assessment shoreline changes of El Alamein and Marina coastal area, northwestern coast of Egypt

New EL Alamein city (NAC) is located on the northwestern coast of Egypt 110 km western of Alexandria and just west of Marina resort. The city layout includes internal artificial lagoons circulated by jetties’ inlets connected to the Mediterranean Sea. Intermediate and multigrade groynes have been proposed to reduce intermediate and downdrift expected erosion. Shoreline erosion at the downdrift area of coastal jetties and sedimentation at lagoons inlets are considered critical issues which shall be balanced and modeled. Marina resort lagoons and protections are considered a prototype for NAC coastal structures and inlets. For Marina resort lagoons case study, shoreline changes have been digitized from Google Earth historical images and field measurements data between 1988 and 2021 by using the Digital Shoreline Analysis System (DSAS) software. Cutting natural longshore sediment deposits by Marina jetties has significantly eroded the downdrift area eastern of Marina border. Most of Marina downdrift area was under accretion(up to + 10 m/year) and little erosion areas before the protection work from 1985 to 1988 and with an average rate of −1.00 m / year from 1988 to 2001 during the construction of the jetties and groynes and with an average rate of −1.20 m/ year after the construction stages between 2005 and 2018. High rates of erosion with an average rate of −4.30 m/year were identified between 2019 and 2021 with the start of NAC coastal proposed structures. This research aims to assess the historical and current situation of NAC shoreline changes and use the similar near project of Marina resort to identify and mitigate the side effects of the proposed protection works of New EL Alamein City.

Mercury pollution in the soil and river water of the Ratai watershed by artisanal and small-scale gold mining activities in Pesawaran District, Lampung, Indonesia

<p>The high risk of mercury pollution in the Ratai watershed due to artisanal and small-scale gold mine activities in Pesawaran District, Lampung, Indonesia, was evaluated. Studies are needed to improve the understanding of the effect of heavy metal pollution, especially mercury (Hg), in soil and river water along the watershed because of erosion. The Universal Soil Loss Equation (USLE) integrated with Geographic Information Systems (GIS) model was used to analyze the transport of mercury (Hg) from nonpoint source pollution loads to the Way Ratai River using rainfall-based erosion. Soils and river water samplings were conducted in 2020. Biophysical conditions, the land cover, and the rainfall data of the Ratai watershed were also taken into account. The results indicated that Hg concentrations in the soil and the river water were high, ranging from 0.26-28.9 mg L<sup>-1</sup> and from 0.08-14.1 mg L<sup>-1</sup>, respectively. The reason for the high Hg contents in the soils and the river waters was the high erosion rate in the watershed. As the study area was characterized by high rainfall erosivity and low to high soil erodibility, the erosion-caused Hg contamination in soil and water can be significant if no conservation strategies are developed.</p>

SOIL EROSION BY HAND TOOLS FOR SMALL-SCALE TILLAGE ON HILLSLOPES ASSESSED THROUGH THE UNIVERSAL SOIL LOSS EQUATION

The objective of this study was to evaluate and compare the erosion rates generated by two types of hand tools for small-scale tillage on a hillslope, using experimental tests and the Universal Soil Loss Equation (USLE). The hand tools evaluated were a conventional hoe and a redesigned furrowing hoe. The experimental work was conducted in a 145 m2 plot with an average slope of 45% in Colombia. Three treatments were evaluated: a) Zero tillage and no herbicide (control); b) tillage with a conventional hoe plus herbicide; c) tillage with a furrowing hoe plus herbicide. Each treatment was represented by a sedimentation plot, using three repetitions in blocks (lower, middle, and upper parts of each plot), according to the maximum slope gradient. Both hand tillage tools generated high to extremely high erosion rates with differences of up to 8.1 times between them. Both types of tools accelerated soil erosion rates, being higher in furrowing hoe tillage. The USLE method showed no differences in erosion rates between the tillage methods, while differences were found in the experimental tests. This is explained by the lower sensitivity of the USLE to detect small-scale changes in factors such as soil type, cover, and slope.

Soil erosion prediction and risk assessment using RUSLE model and GIS techniques in the Nangka watershed

Soil erosion in the Nangka watershed has always been a matter of concern. Over the last decade, soil erosion has led to continuous environmental problems. A thorough examination of the extent of the problem was required to identify an appropriate soil conservation strategy within the watershed. This study was conducted to observe erosion rates and map out the erosion hazard level. Erosion predictions were analysed by using the Revised Universal Soil Loss Equation (RUSLE) model with the help of ArcGIS software. RUSLE was selected because of its quantitative ability to estimate average annual soil erosion and its compatibility with the GIS interface. The potential hazard of soil erosion was classified and ranked into five class categories as set by the national authority. The results reveal that the Nangka watershed is prone to soil erosion with the annual average values ranging from 1.33 Mg·ha –1·y –1 to 2472.29 Mg·ha –1·y –1. High soil erosion rates of 9.8% are in severe (class IV) and very severe (class V) conditions, primarily in the upper course of the watershed. The low annual average of soil erosion (class I and class II), which accounted for 75.95% of the total erosion, mostly took place in the steepness below 35%. The remaining area of 14.25% within the watershed is in moderate condition (class III). It is expected that the results of this study will help the authority in the implementation of soil conservation measures.

CAVITATION EROSION RESISTANCE OF HIGH-ALLOYED Fe-BASED WELD HARDFACINGS DEPOSITED VIA SMAW METHOD

In order to investigate the cavitation erosion (CE) resistance of high-alloyed ferrous hardfacings, the three different deposits were pad welded by the shielded metal arc welding (SMAW) method. Consumable electrodes differed in the content of carbide-forming elements, and pad welds were deposited onto the S235JR structural. The CE tests, conducted according to ASTM G32 standard, indicated that hardfacings reveal lower mass loss than the reference stainless steel AISI 304 (X5CrNi18-10). The hardfacings show increasing resistance to CE in the following order: Cr-C < Cr-C-Mo < Cr-C-Mo-V-W. The reference steel revealed more than twenty times higher material loss in the CE test than Cr-C-Mo-V-W hardfacing, which had outstanding hardness (825HV0.3). The profilometric measurements and scanning electron microscopy investigations showed large changes in valley and peak sizes of the roughness profiles for materials which displayed high erosion rates. The erosion mechanism of the coatings can be classified as brittle-ductile and relies on cracking, chunk removal of material, pits and craters formation, and deformation of fractured material tips and edges. Hardfacing materials failed primarily due to brittle fractures with different severities. Specimen surface degradation follows the changes in Ra, Rz, Rv, and Rp roughness parameters and well-corresponds to the proposed roughness rate (RR) parameter.

Vegetation changes and sediment dynamics in the Lake Alaotra region, central Madagascar

Madagascar is known for its high erosion rates in the central highlands, yet the role of human disturbance versus natural processes is not well understood and is a topic of ongoing debate. At present the necessary quantitative data to couple vegetation dynamics and sediment fluxes over time in Madagascar is scarce. This study aims to provide more insight in vegetation changes and sediment transfers over the last millennia in the Lake Alaotra region, and specifically on the role of human disturbances and natural processes. Our vegetation reconstruction is based on pollen records from two lake sediment cores, covering the last 2600 years. Sediment accumulation rates were calculated from cores obtained from the floodplains, from wetlands surrounding the lake, and from Lake Alaotra itself. Our data show an early opening in the landscape, between 2050 and 1700 cal a BP, with a transition from a wooded grassland or woodland/grassland mosaic towards open grassland and an increase in charcoal accumulation rates. (Indirect) human impact is suggested as the main driver for these vegetation changes. Floodplain and wetland sediment accumulation rates only increase in the last 1000 years and peak in the last 400 years. This increased accumulation can mainly be linked to the increased anthropogenic pressure (grazing and farming activities) that triggered increased lavaka (gullies) activity. No changes in accumulation rate were observed in Lake Alaotra, indicating that most sediments are buffered in the floodplains and wetlands. Overall, our pollen and charcoal data suggest an indirect effect of human disturbance on vegetation shifts whilst strong evidence was found for a direct effect of human disturbance on sediment accumulation through intensified use of the grasslands.

Assessment of long-term land use and land cover change effects on soil erosion and soil organic carbon stock in humid ecosystem condition

This study examined the consequences of land use and cover (LULC) changes on soil erosion and soil organic carbon in the Ünye district of Ordu province in the Central Black Sea Region where humid conditions prevailed in 1999, 2009, and 2019. GIS-based Revised Universal Soil Loss Equation (RUSLE) modeling approach, geostatistics and remote sensing techniques were employed in the study. According to the results considering the long years in the study area, the most relative change among LULC species was hazelnut fields with an increase of 167%. In this process, it has been determined that there are few spatial changes that occurred in artificial areas and pasture lands. In addition, in the classes of soil erosion rates defined by RUSLE, the areas classified as Very Low–Low (< 5 tons ha−1 year−1) for many years inhabit the largest area in the study area. The loss in the amount of soil organic carbon (SOC) is determined to have occurred mostly in areas with Very Low and Low erosion rates. However, it has been determined that SOC loss ensues in areas with Very High (> 20 tons ha−1 year−1) erosion rates, albeit slightly. Therefore, even in the areas with very slight erosion, soil conservation practices should be expanded to secure the long-term sustainability of the production system, especially in agriculture and hazelnut areas.

Loss of Mississippi Diamondback Terrapin (Malaclemys terrapin pileata) Nesting Habitat in the Northern Gulf of Mexico

Diamondback terrapins (Malaclemys terrapin) are a species of turtle that occupy coastal tidal marshes and nest on sandy areas above the high-tide line. Within the Grand Bay National Estuarine Research Reserve, Mississippi diamondback terrapin (M. t. pileata) shoreline nesting habitat at Grand Battures (also known as South Rigolets Island) has decreased from a 2.34-km length of surveyable shoreline in 2014 to a 1.45-km length of shoreline in 2021. Depredated nest surveys in 2021 detected the lowest number of nests to date at this location, with increased search effort, and this is likely due to the high rates of erosion described for this area.

The Utilization of Sentinel-1 Soil Moisture Satellite Imagery for Runoff Coefficient Analysis

Soil moisture content can provide information about the relationship between runoff coefficient and water availability to increase agricultural productivity and measure potential erosion rates. Observation of soil moisture content sometimes cannot be directly measured. Therefore, the study was conducted to develop practical soil moisture monitoring techniques using Sentinel-1 satellite images. Moisture content measurements obtained from the Sentinel-1 satellite image are pre-processed through the Sentinel Application Platform (SNAP), which is then processed using Dubois model to get the soil permittivity value from the backscatter value (σ◦). The moisture content was obtained using Topp’s model. The gravimetric methods in situ soil tests were used to validate the soil moisture content estimation obtained from Sentinel-1 image processing. Based on this research, the Sentinel-1 satellite provides a solution for monitoring soil moisture. The relationship between moisture content and runoff coefficient shows a greater the soil moisture value, the higher the runoff coefficient will obtain. This study proves that the developed land and valley condition has a high runoff coefficient. A high runoff coefficient value has susceptibility to high erosion rates. Sites with similar characteristics need to consider the appropriate land cover to ensure the sustainability of land conservation while still benefiting from agricultural activities.

The relationship between channel width changes with confinement index and flood power of an extreme flood (Case study: Ilam Dam)

Extreme floods are able to execute river geomorphological variations with a wide and substantial geological changes. Former studies of extreme floods have reported a reach of geomorphic replies from negligible change to catastrophic channel change. This article provides an evaluation of the geomorphic effects of a scarce, great value event that occurred in the Ilam Dam upstearim, on 29 October 2015. Variations in geomorphic replies among reaches are examined in the context of changes in flood power, channel competence and lateral confinement index by the use of field survey and Satellite Images (IRS). In this research which is focused on the plan of spatial units, channel width variations and calculation of peak discharges were used to estimate cross-sectional stream power and unit stream power. The analysis was performed for the widening (width ratio) at reach scale. The total data set includes 38 reaches. Because of the 2015 flood, the largest value of widening was 29 m (Reach 13) and it demonstrated a 100% change in the channel width. Flood power peak was calculated 10631 W m−2 along the rather confined reaches (Reach 31) and was much lower along the unconfined reaches. The tendency of high stream power values, and resultant high erosion rates, within the confined and partly confined reaches is a subordinate of the higher energy slope of the steeper.

Soil weathering dynamics and erosion in a dry oceanic area of the southern hemisphere (Otago, New Zealand)

Landscape evolution is driven by tectonics, climate and surface denudation. In New Zealand, tectonics and steep climatic gradients cause a dynamic landscape with intense chemical weathering, rapid soil formation, and high soil losses. In this study, soil, and elemental redistribution along two adjacent hillslopes in East Otago, New Zealand, having different landscape settings (ridge versus valley) are compared to identify soil weathering and erosion dynamics. Fallout radionuclides (239+240Pu) show that over the last ~ 60 years, average soil erosion rates in the valley (~ 260 [t km−2 year−1]) are low compared to the ridge (~ 990 [t km−2 year−1]). The ridge yields up to 26% lower soil weathering intensity than the topographical-protected valley. The lowest soil weathering intensity is found at both hilltop positions, where tors (residual rocks) are present and partially disintegrate. The soil weathering intensity increases with distance from tors, suggesting that tors rejuvenate the chemical weathering signature at the hilltop positions with fresh material. The inversed and decreasing weathering degree with all soil depth indicates that the fresh mineral contribution must be higher at the soil surface than at the bedrock weathering front. Higher erosion rates at the exposed ridge may be partially attributed to wind, consistent with rock abrasion of tors, and low local river sediment yields (56 [t km−2 year−1]). Thus, the East Otago spatial patterns of soil chemistry and erosion are governed by tor degradation and topographic exposure.

Rehabilitation of eroded trails and gullies on quartzite rock outcrops with native species in a high-altitude grassland

The quartzite rock outcrops and the native vegetation of grasslands located at the Serra da Calçada Mountain in Minas Gerais State (Brazil) have been severely degraded by extreme sports activities such as motocross and off-road vehicles, greatly damaging the abundant headwaters. The main consequences thereof were hilly and gully erosion processes with soil loss and the deviation of the water from its original paths. However, currently, there is no report of successful restoration efforts in severely eroded outcrops in Brazilian high-altitude grasslands (campo rupestre). Through the Universal Soil Loss Equation (USLE), we found a high general erosion rate in the study site (669.91 t·ha−1·year−1), and the specific soil loss provoked by off-road vehicles on trails was significantly greater (49 m3 per 100 m2) than that caused by mountain bikes and trekking (5.8 m3 per 100 m2). We performed the physical reconstruction of eroded outcrops and surface water flow paths by allocating locally available quartzite rocks. These rocks were inoculated with different species of bryophytes and planted with native species under two treatments: un-inoculated and inoculated with arbuscular mycorrhizal fungi (AMF) spores of the Rhizophagus irregularis species. After 2 years, the bryophyte communities showed a similar pattern to the preserved site, and the AMF inoculation favoured plant establishment of most species, especially of the Asteraceae, Cyperaceae, Fabaceae, Malpighiaceae, Orchidaceae and Poaceae families. The AMF also improved the soil fertility, highlighting soil P, SOM, CEC, NH4+-N as well as soil water content and water retention capacity. Poaceae family species showed an outstanding occupation, which was considered a functional indicator of rehabilitation success, functioning as a “hydraulic carpet” for water exportation, conduction and drainage across the outcrops. This study provides an eco-technology to restore severely eroded outcrops over headwaters using native species in the Brazilian high-altitude grasslands.

Using the TELEMAC model for analyzing the hydrodynamic regime in the Vam Nao River, Vietnam

The Vam Nao River is located Vietnamese Mekong Delta’s upstream, plays the role of transferring flow from the Tien River to the Hau River and balances the discharge for two of these main branches. Hence, the hydrodynamic regime is very complicated. In 2017, there was a severe riverbank failure, resulting in the loss of many houses and negative impacts on the local people. So, in this research, the TELEMAC model was applied to simulate flow and bed change, combined with field surveys, thereby analyzing the hydrodynamic regime of this river. The model was calibrated using the water level, discharge and suspended load data. The simulation results show that the flow has only one direction from the Tien River to Hau. The maximum velocity in the flood season is 1.66 m/s, the discharge is 8298 m3/s (in 2017), the flow after the confluence appears the vortex. Moreover, the confluence area has a rather high erosion rate, up to 1.2 m/year. According to data collected nearly 30 years, the Vam Nao River’s topographic data signify the riverbed is growing to expand and deepen, over 43 m after the confluence and distributed near the riverbank. With this development trend, it is necessary to continuously monitor to provide early warnings to minimize damages due to the risks of riverbank failure.

Analyzing Various Factors Affecting Farmers’ Willingness to Adopt Soil Erosion Control Measures in the Sebeya Catchment, Rwanda

Soil erosion is a worldwide environmental problem leading to low agricultural productivity and water quality degradation. Improving soil erosion control measures is essential. This study reports the results of a survey of 75 farmers, using structured interviews, field observations, and focus groups to analyze farmers’ perceptions concerning current and future efforts to adopt Soil Erosion Control (SEC) measures in the Sebeya catchment located in the Western Province of Rwanda. Various factors influencing farmers’ perceptions of soil erosion causes, effects, and willingness to adopt SEC measures were analyzed using descriptive statistics and SPSS (Version 20), including t-tests, chi-square tests, and a binary logistic regression model. Chi-square test results indicate that gender, farmer age, land ownership, farmland size, social media access, and credit access were strongly associated (p &lt; 0.05) with the adoption of SEC measures, while marital status and education were not. A binary logistic regression model showed that among farmers’ socioeconomic characteristics, farming experience (B = 0.749; p = 0.020) and access to socio media (B = 2.107; p = 0.027) were positively correlated, while age (B = −0.642; p = 0.035) and gender (B = −2.034; p = 0.032) were negatively correlated (p &lt; 0.05) with the adoption of SEC measures. In order to mitigate high soil erosion rates and increase food production, there is a need for the government to support farmers, and train them. A highly skilled technical team should be mobilized to assist in implementing SEC measures in the Sebeya catchment.

Effects of cropland abandonment and afforestation on soil redistribution in a small Mediterranean mountain catchment

In slopes of Mediterranean mid-mountain areas, land use and land cover changes linked to the abandonment of cropland activity affect soil quality and degradation and soil redistribution; however, limited attention has been paid to this issue at catchment scale. This paper evaluates the effects of cropland abandonment and post-land abandonment management (through natural revegetation and afforestation) on soil redistribution rates using fallout 137Cs measurements in the Araguás catchment (0.45 km2, Central Spanish Pyrenees). A total of 52 soil core samples, distributed in a regular grid, from the first 30–40 cm and 9 sectioned reference samples were collected across the catchment and soil properties were analysed. Fallout 137Cs was measured in a 5 cm sectioned references samples and in bulk grid samples. 137Cs inventories were used to estimate soil erosion and deposition rates across the catchment. Results show that the highest erosion rates were recorded under sparsely vegetated sites in the badland area, while the lowest rates were found in the afforested area, but no significant differences were observed between the different uses and covers in soil redistribution rates likely due to a long history of human intervention through cultivation in steep slopes and afforestation practices. However, the recovery of the soil organic matter in afforested areas suggest that afforestation can reduce soil degradation at long-term scale. The information gained achieve a better understanding of soil redistribution dynamics and provide knowledge for effective land management after cropland abandonment of agroecosystems in Mediterranean mountain areas.

The Age and Erosion Rate of Young Sedimentary Rock on Mars

The Medusae Fossae Formation (MFF) is an enigmatic sedimentary unit near the equator of Mars, with an uncertain formation process and absolute age. Due to the heavily wind-eroded surface, it is difficult to determine the absolute model age of the MFF using a one-parameter model based on the crater size–frequency distribution function with existing crater count data. We create a new two-parameter model that estimates both age and a constant erosion rate (β) by treating cratering as a random Poisson process. Our study uses new crater count data collected from Context Camera imagery for both the MFF and other young equatorial sedimentary rock. Based on our new model, the Central MFF formed >1.5 Gyr ago and had low erosion rates (<650 nm yr−1), whereas the East MFF, Far East MFF, and Zephyria Planum most likely formed <1.5 Gyr ago and had higher erosion rates (>740 nm yr−1). The top of Aeolis Mons (informally known as Mount Sharp) in Gale Crater and Eastern Candor have relatively young ages and low erosion rates. Based on the estimated erosion rates (since fast erosion permits metastable shallow ice), we also identify several sites, including Zephyria Planum, as plausible locations for shallow subsurface equatorial water ice that is detectable by gamma-ray spectroscopy or neutron spectroscopy. In addition to confirming <1.5 Gyr sedimentary rock formations on Mars, and distinguishing older and younger MFF sites, we find that fast-eroding locations have younger ages and MFF locations with slower erosion have older best-fit ages.