Biological soil crusts influence carbon release responses following rainfall in a temperate desert, northern China

Abstract

How soil cover types and rainfall patterns influence carbon (C) release in temperate desert ecosystems has largely been unexplored. We removed intact crusts down to 10 cm from the Shapotou region, China, and measured them in PVC mesocosms, immediately after rainfall. C release rates were measured in soils with four cover types (moss‐crusted soil, algae‐crusted soil, mixed (composed of moss, algae, and lichen)‐crusted soil, and mobile dune sand). We investigated seven different rainfall magnitudes (0–1, 1–2, 2–5, 5–10, 10–15, 15–20, and >20 mm) under natural conditions. C release from all four BSCs increased with increasing rainfall amount. With a rainfall increase from 0 to 45 mm, carbon release amounts increased from 0.13 ± 0.09 to 15.2 ± 1.35 gC m−2 in moss‐crusted soil, 0.08 ± 0.06 to 6.43 ± 1.23 gC m−2 in algae‐crusted soil, 0.11 ± 0.08 to 8.01 ± 0.51 gC m−2 in mixed‐crusted soil, and 0.06 ± 0.04 to 8.47 ± 0.51 gC m−2 in mobile dune sand, respectively. Immediately following heavy rainfall events (44.9 mm), moss‐crusted soils showed significantly higher carbon release rates than algae‐ and mixed‐crusted soils and mobile dune sands, which were 0.95 ± 0.02, 0.30 ± 0.03, 0.13 ± 0.04, and 0.51 ± 0.02 μmol CO2 m−2 s−1, respectively. Changes in rainfall patterns, especially large rain pulses (>10 mm) affect the contributions of different soil cover types to carbon release amounts; moss‐crusted soils sustain higher respiration rates than other biological crusts after short‐term extreme rainfall events.

Desiccation and rehydration of mosses greatly increases resource fluxes that alter soil carbon and nitrogen cycling

“…The quality or chemistry of C released in bryotic pulses might affect particular groups of microbes differently based on their substrate preference (Luo et al, ; Six & Jastrow, ; Wang et al, ). Longer term and in situ studies will be needed to confirm how bryotic pulses influence soil C pools, but the addition of recalcitrant or complex C compounds in throughfall during rehydration could be a mechanism by which mosses may increase soil organic matter accumulation (Gornall et al, ; Lamontagne, ; Sedia & Ehrenfeld, ; Sun et al, ; Zhao et al, ).…”

“…Longer term and in situ studies will be needed to confirm how bryotic pulses influence soil C pools, but the addition of recalcitrant or complex C compounds in throughfall during rehydration could be a mechanism by which mosses may increase soil organic matter accumulation (Gornall et al, 2007;Lamontagne, 1998;Sedia & Ehrenfeld, 2005;Sun et al, 2017;Zhao et al, 2014).…”

“…Like vascular plants, mosses modify their environment by buffering soil temperature and moisture, decreasing surface water runoff and enhancing soil water retention (Blok et al, ; Gornall, Jónsdóttir, Woodin, & Van der Wal, ; Pócs, ; Veneklaas et al, ). Mosses and vascular plants both have a positive influence on soil organic matter, soil total carbon (C) and soil total nitrogen (N), which for mosses has been attributed to their direct effects on soil temperature and moisture (Gornall et al, ; Lamontagne, ; Sedia & Ehrenfeld, ; Sun et al, ; Turetsky, Mack, Hollingsworth, & Harden, ; Zhao, Li, Zhang, Hu, & Chen, ). Unlike vascular plants, the high cation‐exchange and water holding capacity of moss tissue leads to the substantial accumulation of nutrients from symbiotic nitrogen fixation, precipitation and forest canopy throughfall (Lagerström, Nilsson, Zackrisson, & Wardle, ; Street et al, ; Turetsky et al, ).…”

Soil respiration sensitivities to water and temperature in a revegetated desert

“…Pulse effect induced by water addition on soil respiration was ignored, because measurements were always conducted after 10 h of water treatment. Generally, pulse effect was apparent in the dry season, and the respiration rate enhanced immediately after a sudden increase in SWC and lasted for a few days to even a month [e.g., Xu et al ., ; Bowling et al ., ; Zhao et al ., ]. The incubation and measurement were conducted completely in the dark, so photosynthesis by crustal organism was ignored.…”

“…No researchers studied change in SRW caused by temperature, and little attention was paid to other factors. Soil properties, especially soil texture, soil water availability, and biological soil crusts (BSCs) in water‐limited ecosystems, had predominant effects on soil respiration [e.g., Belnap et al ., ; Sponseller , ; Wilske et al ., ; Cable et al ., , ; Bowling et al ., ; Castillo‐Monroy et al ., ; Zhao et al ., ].…”