Carbon Flux of Biological Soil Crusts Associated With Xeric Shrublands During Drying and Wetting Cycles

Background

Biological soil crusts (BSCs) play a pivotal role in arid ecosystems, influencing carbon (C) dynamics in response to changing conditions, especially water availability. Understanding their adaptability is crucial for ecosystem management.

Aims

This study aims to elucidate the C dynamics of BSCs in regulated drying-wetting cycles, exploring immediate responses across different temporal scales (hourly and daily) and their relationship with environmental factors (air temperature, relative humidity, and radiation).

Methods

BSCs were collected at nine sites in the Chihuahuan Desert with preserved xeric shrublands. Samples were subjected to controlled drying-wetting cycles, and C fluxes were measured at different daily and hourly periods. Environmental conditions (air temperature, relative humidity, and photosynthetically active radiation) were also monitored.

Results

Following wetting, significant BSC respiration was observed, with a quick decrease throughout the day, related to air temperature. In contrast, C uptake was less affected by wetting and showed a delayed response. C uptake was more sensitive to relative humidity.

Conclusions

We identified the potential role of BSCs in C dynamics (respiration and uptake) in xeric shrublands and the main controls. Our study reveals BSC adaptability to drying-wetting cycles, emphasizing significant respiration and different metabolic activation.