Quantitative effects of vegetation cover on wind erosion and soil nutrient loss in a desert grassland of southern New Mexico,USA |
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Authors: | Junran Li Gregory S Okin Lorelei Alvarez Howard Epstein |
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Institution: | (1) Department of Environmental Sciences, University of Virginia, Clark Hall, 291 McCormick Rd., Charlottesville, VA 22904-4123, USA;(2) Department of Geography, University of California, 1255 Bunche Hall, Box 951524, Los Angeles, CA 90095, USA |
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Abstract: | Wind is a key abiotic factor that influences the dynamics of arid and semiarid systems. We investigated two basic relationships
on vegetation manipulation (grass cover reduction) plots at the Jornada Experimental Range in southern New Mexico: (1) wind
erosion rates (horizontal mass flux and dust emission) versus vegetative cover, and (2) nutrient loss versus vegetative cover.
The results indicate that wind erosion rates and nutrient loss by dust emission are strongly affected by plant cover; however,
the importance of shrubs and grasses in reducing dust flux may not be equal. The dramatic increase of wind erosion between
75% grass cover reduction and 100% grass cover reduction suggests that sparsely distributed mesquites are relatively ineffective
at reducing wind erosion and nutrient loss compared to grasses. Comparisons of nutrients between surface soils and wind blown
dust indicate that aeolian transport is a major cause for the loss of soil nutrients in susceptible environments. We found
that increased aeolian flux over three windy seasons (March 2004–July 2006) removed up to 25% of total organic carbon (TOC)
and total nitrogen (TN) from the top 5 cm of soil, and about 60% of TOC and TN loss occurred in the first windy season (March–July
2004). The balance between net loss of nutrients by aeolian processes and the addition of nutrients by biotic processes changed
from negative (net loss) to positive (net accumulation) between 50% grass cover reduction and 25% grass cover reduction. The
estimated lifetime of surface soil TOC and TN of about 10 years on the plot with 100% grass cover reduction indicates that
impacts of wind erosion on soil resources can occur on very short timescales. |
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Keywords: | Aeolian processes Deserts Soil nitrogen Soil carbon Vegetation cover Wind erosion Windblown sediment |
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