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

Abstract

Mosses often have positive effects on soil carbon and nitrogen cycling, but we know little about how environmentally determined cycles of desiccation and rehydration in mosses influence these processes. In this context, we compared carbon and nitrogen in throughfall after precipitation passed through eight moss species that were either hydrated continuously or desiccated and rehydrated. Also, the throughfall of four moss species was added to soil and used to determine the net effect of carbon and nitrogen added in moss throughfall on soil CO2 and N2O efflux. Depending on the species, desiccated‐rehydrated (rehydrated) mosses lost 2–31 times more carbon in throughfall than mosses that were continuously hydrated (hydrated). Hydrated mosses lost little to no detectable nitrogen, whereas most rehydrated mosses lost some nitrogen in throughfall. Throughfall from both hydrated and rehydrated mosses generated higher CO2 and N2O efflux than water treated soils, but rehydrated moss throughfall promoted larger N2O efflux than hydrated moss throughfall. Throughfall from hydrated mosses caused net negative changes in soil carbon and had very little effect on soil nitrogen, whereas throughfall from rehydrated mosses generated positive changes in soil carbon and nitrogen. Synthesis. Our results indicate that resources lost from desiccated mosses during rehydration influence soil carbon and nitrogen transformations and may be important drivers of carbon and nitrogen cycling and storage in ecosystems.

Strategies for restoring the structure and function of lichen‐moss biocrust communities

“…vary between restoration plots with mosses and control plots. Mosses lose C and N during cycles of desiccation and rehydration as a result of cellular damage; resources that can be carried away from rehydrating mosses in precipitation, transferred to soil, and accessed by soil microbes (Slate et al 2019). As mosses reestablished, rehydration related pulses of C and N may have promoted soil N immobilization, accounting for lower NH 4 -N levels measured in plots with moss versus no-moss control plots.…”

Precipitation regime controls bryosphere carbon cycling similarly across contrasting ecosystems

“…ecosystem respiration, ER), and to reduce the loss of dissolved organic carbon (DOC) in leachates (Öquist et al 2014). Meanwhile, changes in precipitation frequency that lead to increased drying–rewetting cycles can promote the release of DOC in leachates from mosses (Slate et al 2019) and from soil (Gordon et al 2008). Therefore, projected shifts in precipitation regime due to climate change could potentially alter both C uptake and C loss in moss‐dominated ecosystems, with potential consequences for ecosystem C cycling and C storage.…”

Mosses reduce soil nitrogen availability in a subarctic birch forest via effects on soil thermal regime and sequestration of deposited nitrogen

“…(c) The absence of roots also implies the lack of root exudates. Pulses of labile (carbon) compounds may, however, be leached from bryophyte layers into the soil after drying-rewetting cycles and serve as energy source for soil microbes (Slate et al, 2019;Wilson & Coxson, 1999). (d) Decomposition rates of bryophyte litter are considerably lower than those of vascular plant litter (Hobbie, 1996;Lang et al, 2009), which has been ascribed to a high content of lignin-like compounds in moss biomass, specific cell wall polysaccharides or cell components with antimicrobial properties (Hájek et al, 2011;Turetsky, 2003;Verhoeven & Toth, 1995).…”