Impact of Environmental Factors and Biological Soil Crust Types on Soil Respiration in a Desert Ecosystem

Abstract

The responses of soil respiration to environmental conditions have been studied extensively in various ecosystems. However, little is known about the impacts of temperature and moisture on soils respiration under biological soil crusts. In this study, CO2 efflux from biologically-crusted soils was measured continuously with an automated chamber system in Ningxia, northwest China, from June to October 2012. The highest soil respiration was observed in lichen-crusted soil (0.93±0.43 µmol m−2 s−1) and the lowest values in algae-crusted soil (0.73±0.31 µmol m−2 s−1). Over the diurnal scale, soil respiration was highest in the morning whereas soil temperature was highest in the midday, which resulted in diurnal hysteresis between the two variables. In addition, the lag time between soil respiration and soil temperature was negatively correlated with the soil volumetric water content and was reduced as soil water content increased. Over the seasonal scale, daily mean nighttime soil respiration was positively correlated with soil temperature when moisture exceeded 0.075 and 0.085 m3 m−3 in lichen- and moss-crusted soil, respectively. However, moisture did not affect on soil respiration in algae-crusted soil during the study period. Daily mean nighttime soil respiration normalized by soil temperature increased with water content in lichen- and moss-crusted soil. Our results indicated that different types of biological soil crusts could affect response of soil respiration to environmental factors. There is a need to consider the spatial distribution of different types of biological soil crusts and their relative contributions to the total C budgets at the ecosystem or landscape level.

Does biocrust successional stage determine the degradation of vascular vegetation via alterations in its hydrological roles in semi‐arid ecosystem?

“…Natural vegetation at the site is dominated by Artemisia ordosica (Feng et al, 2014). The site is located at the edge of the Mu Us Desert in the transition between arid and semi-arid climatic zones, at an elevation of 1,550 m a.s.l.…”

Diel-scale temporal dynamics recorded for bacterial groups in Namib Desert soil

“…Indeed, other than studies focused on Cyanobacteria2324 and a temperature manipulation experiment25, short temporal community dynamics have been neglected. This is surprising given the fact that significant differences in specific desert soil processes have been recorded over the diel (24 hrs) cycle (e.g., CO 2 flux refs 26, 27, 28). In addition, asymmetrical diel warming; i.e., the increase in daily minimum temperature (T min ), is widely observed and set to continue in terrestrial ecosystems2930 and is likely to impact negatively on microbial communities and their processes31.…”

Impact of geomorphic disturbance on spatial variability of soil CO2 flux within a depositional landform

“…Previous studies demonstrated that soil water content is the predominant source of soil CO 2 flux, due to the impacts of soil moisture in increasing metabolic activity (Feng et al, ; Leon et al, ; Maestre & Cortina, ). Conversely, our results show how a geomorphic disturbance, with local scale variations in the structuring and functioning of landscape, can disturb the soil water content—soil CO 2 flux equation via the occurrence of other regulatory controls at points with higher moisture content.…”