Latitudinal effect of vegetation on erosion rates identified along western South America

Science ◽  
2020 ◽  
Vol 367 (6484) ◽  
pp. 1358-1361 ◽  
Author(s):  
J. Starke ◽  
T. A. Ehlers ◽  
M. Schaller
Keyword(s):  
South America ◽  
Vegetation Cover ◽  
Surface Processes ◽  
Competing Interactions ◽  
Erosion Rates ◽  
Western Cordillera ◽  
Millennial Time Scale ◽  
Vegetation Gradient ◽  
Cosmogenic Radionuclide ◽  
Latitudinal Effect

Vegetation influences erosion by stabilizing hillslopes and accelerating weathering, thereby providing a link between the biosphere and Earth’s surface. Previous studies investigating vegetation effects on erosion have proved challenging owing to poorly understood interactions between vegetation and other factors, such as precipitation and surface processes. We address these complexities along 3500 kilometers of the extreme climate and vegetation gradient of the Andean Western Cordillera (6°S to 36°S latitude) using 86 cosmogenic radionuclide–derived, millennial time scale erosion rates and multivariate statistics. We identify a bidirectional response to vegetation’s influence on erosion whereby correlations between vegetation cover and erosion range from negative (dry, sparsely vegetated settings) to positive (wetter, more vegetated settings). These observations result from competing interactions between precipitation and vegetation on erosion in each setting.

scholarly journals Quality assessment of chronologies in Latin American pollen records: a contribution to centennial to millennial scale studies of environmental change

2015 ◽  
Vol 11 (2) ◽  
pp. 1219-1262 ◽  
Author(s):  
S. G. A. Flantua ◽  
H. Hooghiemstra ◽  
M. Blaauw
Keyword(s):  
South America ◽  
Quality Assessment ◽  
Latin American ◽  
Time Windows ◽  
Uncertainty Assessment ◽  
Last Deglaciation ◽  
Age Model ◽  
Millennial Time Scale ◽  
Pollen Records ◽  
Millennial Scale

Abstract. The newly updated inventory of the Latin American Pollen Database (LAPD) offers an important overview of data available for multi-proxy and multi-site purposes. However, heterogeneous paleoecological databases are not suitable to be integrated without an uncertainty assessment of existing chronologies. Therefore, we collected all chronological control points and age model metadata from the LAPD literature to create a complementary chronological database of 5116 dates from 1097 pollen records. We start with an overview on chronological dating and reporting in Central and South America. Specific problems and recommendations for chronology reporting are discussed. Subsequently, we implement a temporal quality assessment of pollen records from northwest South-America to support research on climate forcers and responses at a centennial-millennial time-scale. New chronologies are generated for 233 pollen records based on updated calibration curves. Different time windows are discussed on sample resolution and temporal uncertainty. Approximately one in four pollen diagrams depicts < 500 years resolution data at the Younger Dryas/Holocene transition. Overall, our analyses suggest that the temporal resolution of multi-site syntheses of late Pleistocene fossil pollen records in the northwest South-America is ca. 240 years, a resolution which allows analysis of ecological responses to centennial-millennial-scale climate change during the last deglaciation.

How spatial vegetation distribution affects soil erosion and sediment transport

2021 ◽  
Author(s):  
Malte Kuegler ◽  
Thomas Hoffmann ◽  
Jana Eichel ◽  
Lothar Schrott ◽  
Juergen Schmidt
Keyword(s):  
Soil Erosion ◽  
Vegetation Cover ◽  
Vegetation Pattern ◽  
Vegetation Coverage ◽  
Future Research ◽  
Initial Increase ◽  
Vegetation Patterns ◽  
Erosion Rates ◽  
Catchment Areas ◽  
The Impact

&lt;p&gt;There are a multitude of factors that affect soil erosion and the process of sediment movement. One particular factor known to have a considerable impact is vegetation coverage within catchment areas.&amp;#160; Previous studies have examined the impact of vegetation cover on erosion.&amp;#160;However, there is a lack of research on how the spatial distribution of vegetation influences erosion rates.&lt;/p&gt;&lt;p&gt;A greater understanding of hillslope erosion is fundamental in modelling previous and future topographic changes under various climate conditions. Here, the physical based erosion model EROSION 3D &amp;#169; is used to evaluate the impact of a variety of vegetation patterns and degrees of vegetation cover on sediment erosion and transport. The model was applied on a natural catchment in La Campana (Central Chile). For this purpose, three different vegetation patterns were created: (i) random distribution, (ii) water-dependent distribution (TWIR) and (iii) banded vegetation pattern distribution. Additional to this, the areas covered by vegetation generated in the first step were expanded by steps of 10% [0...100%]. The Erosion3D &amp;#169; model then was applied on all vegetation patterns and degrees of cover.&lt;/p&gt;&lt;p&gt;Our results show an initial increase of soil erosion with increasing plant coverage within the catchment up to a certain cover threshold ranging between 10 and 40%. At larger vegetation cover soil erosion rates decline. The strength of increase and decline, as well as the cover-threshold is strongly conditioned by the spatial vegetation pattern. In the light of this, future research should pay particular attention to the properties of the plants and their distribution, not solely on the amount of biomass within catchment areas.&lt;/p&gt;

scholarly journals Study of soil erosion risks using remote sensing in Ouergha River watershed (Morocco)

2020 ◽  
Vol 150 ◽  
pp. 03012
Author(s):  
Imane Jaouda ◽  
Ahmed Akhssas ◽  
Latifa Ouadif ◽  
Lahcen Bahi ◽  
Jada Elkasri ◽  
...  
Keyword(s):  
Land Use ◽  
Vegetation Cover ◽  
Severe Drought ◽  
Human Intervention ◽  
Landsat Images ◽  
Erosion Rates ◽  
The North ◽  
Human Practices ◽  
Comparison Of The Results ◽  
Geological Formations

The watershed Ouergha River located in the north of Morocco suffer from vegetation cover degradation, this geographic entity is experiencing intense water erosion linked to the combination of several natural factors, such as the roughness and abundance of rainfall and the predominance of soft geological formations. Human intervention in this vulnerable environment accentuates its fragility by the clearing and degradation of the vegetation cover and the cultivation of land with a steep slope. This work aims to map the spatiotemporal evolution of this degradation by using the spot and Landsat images and the Radar image over a period from 1990 to 2014 data and aims to model its processes of erosion. In fact, the analysis of satellite data identified six main types of land use (eau, foret, reboisement…). It has also shown that the most degraded soils aren’t necessarily those with the greatest erosion rates over the past 15 years and that some soils that have developed well over time have become major exporters of sediments after clearing and cultivation. The comparison of the results of land use has highlighted the harmful impact of human practices on the acceleration of soil degradation. Human intervention, coupled to frequent and severe drought periods, remain the most important factors in the weakening and increasing vulnerability of soils to degradation. The results obtained by this approach made it possible to identify and monitor vulnerable areas at Ouergha watershed where interventions are needed to limit the processes of degradation of the soil and the natural environment.

A novel late Early Miocene assemblage of terrestrial gastropods from Santa Cruz (Patagonia, Argentina)

2015 ◽  
Vol 89 (5) ◽  
pp. 748-761 ◽  
Author(s):  
Sergio E. Miquel ◽  
Pablo E. Rodriguez
Keyword(s):  
South America ◽  
New Taxa ◽  
Vegetation Cover ◽  
First Record ◽  
Early Miocene ◽  
New Taxon ◽  
Santa Cruz ◽  
Dense Vegetation ◽  
Humid Environment ◽  
New Information

AbstractA remarkable fossil assemblage composed of five gastropod taxa is described from the Early Miocene of Santa Cruz (Patagonia, Argentina) in southernmost South America. The assemblage includes extinct and living genera South America, and on geographic distributions and represent background new information on spatial and across time distributions as well as identification of new taxa. A new taxon,Patagocharopa enigmatican. gen. n. sp., is tentatively assigned to Charopidae.Gastrocopta patagonican. sp. (Vertiginidae) represents the oldest record ofGastrocoptain Argentina and the southernmost record for the Americas.Punctum patagonicumn. sp. (Punctidae) represents the first record ofPunctumfor continental South America, and characterized by a protoconch with traces of axial costulae and a teleoconch with strong radial ribs.Zilchogyra miocenican. sp. is the first Miocene record of the charopid genusZilchogyra. Fragments of a possibleScolodonta(Scolodontidae) are recorded. Overall, the assemblage represents an important and useful paleoenvironmental tool. This fauna suggests that a more temperate and humid environment than today—with a more dense vegetation cover—was prevalent at this site during the Early Miocene.

scholarly journals Quantification of water related soil erosion in the transboundary basin of the Bia (West Africa)

2021 ◽  
Vol 384 ◽  
pp. 107-112
Author(s):  
N'diaye Edwige Hermann Meledje ◽  
Kouakou Lazare Kouassi ◽  
Yao Alexis N'Go
Keyword(s):  
Soil Erosion ◽  
West Africa ◽  
Vegetation Cover ◽  
Soil Loss ◽  
Catchment Area ◽  
Erosion Rate ◽  
Random Variable ◽  
Erosion Rates ◽  
Transboundary Basin ◽  
Large Heterogeneity

Abstract. In view of the complexity of the phenomenon of water related soil erosion in the Bia catchment area, linked to a large heterogeneity of soils, to a very scattered and in some places non-existent vegetation cover, and to a poorly distributed precipitation in both space and time, a mapping test of the “specific erosion” random variable is undertaken. The mapping of the intensity of the erosion hazard was carried out using the Universal Soil Loss Model (USLE). The map shows that the basin is generally characterized by relatively moderate erosion rates with an average erosion rate of 16 t/ha/year.

DEGRADATION OF ONE-HUNDRED-METER-SCALE ROCKY EJECTA CRATERS AT THE INSIGHT LANDING SITE ON MARS AND IMPLICATIONS FOR SURFACE PROCESSES AND EROSION RATES

2018 ◽  
Author(s):  
Nicholas H. Warner ◽  
◽  
Julianne Sweeney ◽  
Vamsi Ganti ◽  
Matthew P. Golombek ◽  
...  
Keyword(s):  
Landing Site ◽  
Surface Processes ◽  
Erosion Rates

scholarly journals Control of Tropical Landcover and Soil Properties on Landslides’ Aquifer Recharge, Piezometry and Dynamics

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1491 ◽  
Author(s):  
Pierre Belle ◽  
Bertrand Aunay ◽  
Patrick Lachassagne ◽  
Bernard Ladouche ◽  
Jean-Lambert Join
Keyword(s):  
Vegetation Cover ◽  
Water Budget ◽  
Surface Processes ◽  
Methodological Framework ◽  
Aquifer Recharge ◽  
High Permeability ◽  
Shallow Layer ◽  
Consequent Increase ◽  
Landslide Dynamics

Among the processes controlling landslide dynamics, piezometry plays a major role. The characterization of a landslide’s aquifer recharge (=inflows) is thus indispensable for predicting displacements. In this research, the recharge of the large Grand Ilet landslide in the humid tropical, Reunion Island was characterized through a multi-disciplinary and robust hydrological approach, notably comprising a precise water budget of the landslide (outflows = inflows). Surface processes play a major role in the landslide recharge regime. Runoff is less than 1% of rainfall (2400 mm/year) due to the soil’s high permeability. A large quantity of water (250 mm) is adsorbed in this shallow layer. This reservoir is submitted to high real evapotranspiration (1500 mm/year) due to the dense tropical broad-leaved vegetation. This explains the low aquifer recharge (860 mm/year), the fact that only major rainfall episodes during the rainy season induce recharge, with a consequent increase in landslide velocity, and finally low outflow from the landslide. Therefore, among other operational recommendations, it is necessary to maintain natural vegetation cover over such landslide surface in order to limit aquifer recharge and thus displacements. This study provides a methodological framework for landslide studies, particularly for modeling their recharge/piezometry, and key parameters of their dynamics.

The (un)balance between tectonic and erosion in analog accretionary wedges

2021 ◽  
Author(s):  
Riccardo Reitano ◽  
Claudio Faccenna ◽  
Francesca Funiciello ◽  
Fabio Corbi ◽  
Pietro Sternai ◽  
...  
Keyword(s):  
Steady State ◽  
Spatial Scales ◽  
Theoretical Models ◽  
Force Balance ◽  
Surface Processes ◽  
Accretionary Wedge ◽  
Erosion Rates ◽  
Water Saturated ◽  
State Configuration ◽  
Analog Models

&lt;p&gt;In convergent systems, tectonics, erosion, and sedimentation control orogenic evolution. The nature of the interaction between these factors is still to be unraveled, because of their complex feedback that goes through different time and spatial scales. Here, we try to bind tectonics, erosion, and sedimentation by running laboratory-scale coupled analog models of landscape evolution, in which both tectonic forcing and surface processes are modeled, trying to unravel the nature of these multiple-interrelated processes. The analog apparatus consists of a rectangular box filled with a water-saturated granular material. The deformation is imposed by the movement of a rigid piston (backstop), while surface processes are triggered by simulated rainfall and runoff. We systematically vary the convergence velocity and the rainfall rate, testing how different boundary conditions affect the balance between tectonics and surface processes and the onset of steady-state configurations. We measure the competition between input fluxes (tectonics) and output fluxes (erosion) of material. The results show how analog models never achieve a steady-state configuration in which tectonic rates are perfectly balanced by erosion rates. Tectonics add more material to the accretionary wedge than is removed by erosion (about 2-5 times more). Still, erosional fluxes seem to reach an equilibrium with the applied tectonic flux. The foreland is always overfilled with sediments, and we argued how the storage of sediments in front of a wedge can strongly divert the orogenic system from the &amp;#8220;classical&amp;#8221; steady state configuration. This work analyzes which are the main differences between analog and theoretical models and if/how the results coming from analog models can be exportable when interpreting natural landscape morphologies and force balance.&lt;/p&gt;

Analysis of the interaction between neotectonic and surface processes in a low-land intracratonic setting of South America

2017 ◽  
Vol 438 ◽  
pp. 141-159 ◽  
Author(s):  
Ernesto Brunetto ◽  
Daniela M. Kröhling ◽  
María Cecilia Zalazar ◽  
María Candela Francisconi
Keyword(s):  
South America ◽  
Surface Processes
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