Abstract
Soil respiration (Rs) is a major pathway for carbon cycling and is a complex process involving abiotic and biotic factors. Biological soil crusts (BSCs) are a key biotic component of desert ecosystems worldwide. In desert ecosystems, soils are protected from surface disturbance by BSCs, but it is unknown whether Rs is affected by disturbance of this crust layer. We measured Rs in three types of disturbed and undisturbed crusted soils (algae, lichen, and moss), as well as bare land from April to August, 2010, in Mu Us desert, northwest China. Rs was similar among undisturbed soils but increased significantly in disturbed moss and algae crusted soils. The variation of Rs in undisturbed and disturbed soil was related to soil bulk density. Disturbance also led to changes in soil organic carbon and fine particles contents, including declines of 60–70% in surface soil C and N, relative to predisturbance values. Once BSCs were disturbed, Q 10 increased. Our findings indicate that a loss of BSCs cover will lead to greater soil C loss through respiration. Given these results, understanding the disturbance sensitivity impact on Rs could be helpful to modify soil management practices which promote carbon sequestration.
Highlights
Biological soil crusts (BSCs) are diminutive communities consisting of bacteria, cyanobacteria, fungi, lichens, mosses, and liverworts, all of which form a cohesive thin horizontal layer in association with the mineral soil surface [1, 2]
Soil stability is a primary control over carbon sequestration of managed ecosystems in arid and semiarid regions [9]
Disturbance of BSCs will potentially lead to greater C losses in gases respired and C input in soils under dry condition
Summary
Biological soil crusts (BSCs) are diminutive communities consisting of bacteria, cyanobacteria, fungi, lichens, mosses, and liverworts, all of which form a cohesive thin horizontal layer in association with the mineral soil surface [1, 2]. BSCs have several important identified roles in desert ecosystems, including significant contribution to carbon (C) and nitrogen (N) input (an estimate of 1.0 Pg ha−1 and 30 Tg ha−1 for net uptake of C and N by biocrusts in arid and semiarid regions), soil stability, and influence over patterns of erosion [3,4,5]. The deserts of the world are estimated to contain 10 Pg C [6], with 56 × 1012 g C held in cyanobacterial biomass (a component of biocrusts) in arid and semiarid regions [7]. These numbers illustrate that BSC can sequester substantial C in the crust layer [8]. BSCs are highly susceptible to disturbance, especially in soils with low aggregate stability and dry conditions, such as sands in dry conditions [3, 10]
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