Land degradation in drylands: Interactions among hydrologic–aeolian erosion and vegetation dynamics

Ravi, Sujith; Breshears, David D.; Huxman, Travis E.; D’Odorico, Paolo

doi:10.1016/j.geomorph.2009.11.023

Cited by 340 publications

(216 citation statements)

References 80 publications

(124 reference statements)

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“…Erosion is strongly linked to land degradation in drylands (Lal, 2003;Ravi et al, 2010), and this is the case in Australian rangelands (Bui et al, 2011;Dregne, 1995;Gillieson et al, 1996;Webb et al, 2009). A database of erosion was used to better understand the nature of the degradation that was detected.…”

Section: Land Capability Classificationmentioning

confidence: 99%

“…5b, c) and coincidences of visible disturbance around livestock water points. The relationship between degradation, accelerated rates of erosion, and reduced vegetation cover is well known (Lal, 2001) and erosion is the most widespread and recognizable characteristics of land degradation (Ravi et al, 2010), also a primary impact on loss of soil carbon (Rajan et al, 2010). In the present study, there was a strong overall correlation of average LNS with hillslope erosion and gully density (Fig.…”

Section: Anthropogenic and Environmental Degradationmentioning

confidence: 99%

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Degradation of net primary production in a semiarid rangeland

Jackson

Prince

2016

Biogeosciences

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Abstract. Anthropogenic land degradation affects many biogeophysical processes, including reductions of net primary production (NPP). Degradation occurs at scales from small fields to continental and global. While measurement and monitoring of NPP in small areas is routine in some studies, for scales larger than 1 km 2 , and certainly global, there is no regular monitoring and certainly no attempt to measure degradation. Quantitative and repeatable techniques to assess the extent of deleterious effects and monitor changes are needed to evaluate its effects on, for example, economic yields of primary products such as crops, lumber, and forage, and as a measure of land surface properties which are currently missing from dynamic global vegetation models, assessments of carbon sequestration, and land surface models of heat, water, and carbon exchanges. This study employed the local NPP scaling (LNS) approach to identify patterns of anthropogenic degradation of NPP in the Burdekin Dry Tropics (BDT) region of Queensland, Australia, from 2000 to 2013. The method starts with land classification based on the environmental factors presumed to control (NPP) to group pixels having similar potential NPP. Then, satellite remotely sensing data were used to compare actual NPP with its potential. The difference in units of mass of carbon and percentage loss were the measure of degradation. The entire BDT (7.45 × 10 6 km 2 ) was investigated at a spatial resolution of 250 × 250 m. The average annual reduction in NPP due to anthropogenic land degradation in the entire BDT was −2.14 MgC m −2 yr −1 , or 17 % of the non-degraded potential, and the total reduction was −214 MgC yr −1 . Extreme average annual losses of 524.8 gC m −2 yr −1 were detected. Approximately 20 % of the BDT was classified as "degraded". Varying severities and rates of degradation were found among the river basins, of which the Belyando and Suttor were highest. Interannual, negative trends in reductions of NPP occurred in 7 % of the entire region, indicating ongoing degradation. There was evidence of areas that were in a permanently degraded condition. The findings provide strong evidence and quantitative data for reductions in NPP related to anthropogenic land degradation in the BDT.

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Section: Land Capability Classificationmentioning

confidence: 99%

Section: Anthropogenic and Environmental Degradationmentioning

confidence: 99%

Degradation of net primary production in a semiarid rangeland

Jackson

Prince

2016

Biogeosciences

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“…Dust storms cause soil loss from dry lands and preferentially remove organic matter and the nutrient-rich lightest particles, thereby reducing agricultural productivity. Furthermore the abrasive effect of the dust storm damages young crop plants (Lyles, 1988;Simonson, 1995;Stefanski and Sivakumar, 2009;Ravi et al, 2010). The reduced visibility associated with all forms of dust phenomena impacts the local economy by affecting aircraft aviation and road transportation (De Villiers and Van Heerden, 2007).…”

Section: Introductionmentioning

confidence: 99%

Aerosol's optical and physical characteristics and direct radiative forcing during a shamal dust storm, a case study

Saeed

Al‐Dashti²,

Spyrou

2014

Atmos. Chem. Phys.

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Abstract. Dust aerosols are analyzed for their optical and physical properties during an episode of a dust storm that blew over Kuwait on 26 March 2003 when the military Operation Iraqi Freedom was in full swing. The intensity of the dust storm was such that it left a thick suspension of dust throughout the following day, 27 March. The synoptic sequence leading to the dust storm and the associated wind fields are discussed. Ground-based measurements of aerosol optical thickness reached 3.617 and 4.17 on 26 and 27 March respectively while the Ångstrom coefficient, α 870/440 , dropped to −0.0234 and −0.0318. Particulate matter concentration of 10 µm diameter or less, PM 10 , peaked at 4800 µg m −3 during dust storm hours of 26 March. Moderate Resolution Imaging Spectroradiometer (MODIS) retrieved aerosol optical depth (AOD) by Deep Blue algorithm and Total Ozone Mapping Spectrometer (TOMS) aerosol index (AI) exhibited high values. Latitude-longitude maps of AOD and AI were used to deduce source regions of dust transport over Kuwait. The vertical profile of the dust layer was simulated using the SKIRON atmospheric model. Instantaneous net direct radiative forcing is calculated at top of atmosphere (TOA) and surface level. The thick dust layer of 26 March resulted in cooling the TOA by −60 Wm −2 and surface level by −175 Wm −2 for a surface albedo of 0.35. Slightly higher values were obtained for 27 March due to the increase in aerosol optical thickness. Radiative heating/cooling rates in the shortwave and longwave bands were also examined. Shortwave heating rate reached a maximum value of 2 K day −1 between 3 and 5 km, dropped to 1.5 K day −1 at 6 km and diminished at 8 km. Longwave radiation initially heated the lower atmosphere by a maximum value of 0.2 K day −1 at surface level, declined sharply at increasing altitude and diminished at 4 km. Above 4 km longwave radiation started to cool the atmosphere slightly reaching a maximum rate of −0.1 K day −1 at 6 km.

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“…The aeolian redistribution of fine, easily erodible material is thought to be the other key geomorphic agent acting in these dryland environments [Ravi et al, 2010;Okin et al, 2009]. The increased percentage of bare ground at woody sites reported in this study may result in a greater susceptibility to wind erosion [Gillette and Monger, 2006].…”

Section: Change In Soil C Dynamics Over Vegetation Transitionsmentioning

confidence: 92%

Woody plant encroachment into grasslands leads to accelerated erosion of previously stable organic carbon from dryland soils

et al. 2014

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Drylands worldwide are experiencing rapid and extensive environmental change, concomitant with the encroachment of woody vegetation into grasslands. Woody encroachment leads to changes in both the structure and function of dryland ecosystems and has been shown to result in accelerated soil erosion and loss of soil nutrients. Covering 40% of the terrestrial land surface, dryland environments are of global importance, both as a habitat and a soil carbon store. Relationships between environmental change, soil erosion, and the carbon cycle are uncertain. There is a clear need to further our understanding of dryland vegetation change and impacts on carbon dynamics. Here two grass-to-woody ecotones that occur across large areas of the southwestern United States are investigated. This study takes a multidisciplinary approach, combining ecohydrological monitoring of structure and function and a dual-proxy biogeochemical tracing approach using the unique natural biochemical signatures of the vegetation. Results show that following woody encroachment, not only do these drylands lose significantly more soil and organic carbon via erosion but that this includes significant amounts of legacy organic carbon which would previously have been stable under grass cover. Results suggest that these dryland soils may not act as a stable organic carbon pool, following encroachment and that accelerated erosion of carbon, driven by vegetation change, has important implications for carbon dynamics.

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Land degradation in drylands: Interactions among hydrologic–aeolian erosion and vegetation dynamics

Cited by 340 publications

References 80 publications

Degradation of net primary production in a semiarid rangeland

Degradation of net primary production in a semiarid rangeland

Aerosol's optical and physical characteristics and direct radiative forcing during a shamal dust storm, a case study

Woody plant encroachment into grasslands leads to accelerated erosion of previously stable organic carbon from dryland soils

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