Vertical and Lateral Carbon Flux in a Larrea/Cardon Ecosystem near La Paz, BCS, Mexico

Lateral transport of carbon by wind and water in the form of litter fall could represent a significant portion of carbon entering or exiting an ecosystem. In La Paz, Baja California Sur, Mexico, GCRG established a permanent Eddy Covariance tower in 2001. Eddy Covariance tracks daily, seasonal and yearly ecosystem carbon flux, but may be missing carbon transported laterally. By analyzing the Eddy Covariance data from 2004-2008, along with previously published data from 2001-2003, an 8 year data set of seasonal and annual carbon flux can be produced. The data shows decreasing carbon sinks in the years 2001-2004, to increasing carbon sources to year 2006, after which the carbon source begins to decrease. Seasonally, fall and winter show general carbon sinks following large late summer hurricane events, switching to monthly carbon sources in early spring and increasing through summer.

In this arid, desert ecosystem, litter moved by wind and late summer storm events may play a large role in where carbon stored by the ecosystem is actually stored or decomposed. Lateral flux experiments have been established in the footprint of the tower. These experiments track the amount of litter fall, amount of litter being transported laterally, changes in ground litter stock, and distance litter is moved across the desert landscape. Preliminary data show that litter is being moved by wind from areas outside a localized area (>2500m2). Once total lateral transport of carbon in litter can be established, we can compare these numbers to the Eddy Covariance data. With this information we can establish the role lateral transport of litter plays in the carbon cycle of this ecosystem.

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