Biogeochemistry

, Volume 77, Issue 2, pp 247–263

Impacts of Biological Soil Crust Disturbance and Composition on C and N Loss from Water Erosion

Authors

    • The Natural Resource Ecology LaboratoryColorado State University
    • Institute of Arctic and Alpine ResearchUniversity of Colorado
  • Jeffrey E. Herrick
    • USDA – ARS Jornada Experimental Range
  • Justin Van Zee
    • USDA – ARS Jornada Experimental Range
  • Jayne Belnap
    • The Natural Resource Ecology LaboratoryColorado State University
    • USGS – BRD Canyonlands Field Station
Article

DOI: 10.1007/s10533-005-1424-7

Cite this article as:
Barger, N.N., Herrick, J.E., Van Zee, J. et al. Biogeochemistry (2006) 77: 247. doi:10.1007/s10533-005-1424-7

Abstract

In this study, we conducted rainfall simulation experiments in a cool desert ecosystem to examine the role of biological soil crust disturbance and composition on dissolved and sediment C and N losses. We compared runoff and sediment C and N losses from intact late-successional dark cyanolichen crusts (intact) to both trampled dark crusts (trampled) and dark crusts where the top 1 cm of the soil surface was removed (scraped). In a second experiment, we compared C and N losses in runoff and sediments in early-successional light cyanobacterial crusts (light) to that of intact late-successional dark cyanolichen crusts (dark). A relatively high rainfall intensity of approximately 38 mm per 10-min period was used to ensure that at least some runoff was generated from all plots. Losses of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and ammonium (NH 4 + ) were significantly higher from trampled plots as compared to scraped and intact plots. Sediment C and N losses, which made up more than 98% of total nutrient losses in all treatments, were more than 4-fold higher from trampled plots relative to intact plots (sediment C g/m2, intact = 0.74, trampled = 3.47; sediment N g/m2, intact = 0.06, trampled = 0.28). In light crusts, DOC loss was higher relative to dark crusts, but no differences were observed in dissolved N. Higher sediment loss in light crusts relative to dark crusts resulted in 5-fold higher loss of sediment-bound C and N. Total C flux (sediment + dissolved) was on the order of 0.9 and 7.9 g/m2 for dark and light crusts, respectively. Sediment N concentration in the first minutes after runoff from light crusts was 3-fold higher than the percent N of the top 1 cm of soil, suggesting that even short-term runoff events may have a high potential for N loss due to the movement of sediments highly enriched in N. Total N loss from dark crusts was an order of magnitude lower than light crusts (dark = 0.06 g N/m2, light = 0.63 g/m2). Overall, our results from the small plot scale (0.5 m2) suggest that C and N losses are much lower from intact late-successional cyanolichen crusts as compared to recently disturbed or early-successional light cyanobacterial crusts.

Keywords

Biological soil crust Carbon Canyonlands National Park Colorado Plateau Disturbance Erosion Nitrogen Rainfall simulation Runoff

Copyright information

© Springer 2006