Litter decomposition rates of biocrust-forming lichens are similar to that of vascular plants and are affected by warming in a semiarid grassland

Abstract

25Despite the high relevance of communities dominated by lichens, mosses and cyanobacteria 26 living on the soil surface (biocrusts) for ecosystem functioning in drylands worldwide, no study 27 to date has investigated the decomposition of biocrust-forming lichen litter in situ. Thus, we do 28 not know whether the drivers of its decomposition are similar to those for plant litter (e.g., 29importance of abiotic degradation through UV radiation), the magnitude of lichen decomposition 30 rates and whether they will be affected by climate change. Here we report results from a litter 31 decomposition experiment carried out with two biocrust-forming lichens (Diploschistes 32 diacapsis and Cladonia convoluta) in central Spain. We evaluated how lichen decomposition 33 was affected by warming, rainfall exclusion and the combination of both. We also manipulated 34 the incidence of UV radiation using mesh material that blocked 10% or 90% of incoming UV 35 radiation. Our results indicate that lichens decompose as fast as some plants typical of the region 36 (k~0.3) and that the chemical composition of their thallus drives litter decomposition rates. 37Warming increased decomposition rates of both lichen species, and mediated the effects of 38 photodegradation. While UV exposure accelerated the decomposition of D. diacapsis, it slowed 39 down that of C. convoluta. Our results indicate that biocrust-forming lichens can decompose in 40 the field at a rate similar to that of vascular plants, and that this process will be affected by 41 warming. Our findings further highlight the need of incorporating biocrusts into carbon cycling 42 models to better understand and forecast climate change impacts on terrestrial biogeochemistry. 43 Lichen litter decomposition 3 44

Species‐specific effects of biocrust‐forming lichens on soil properties under simulated climate change are driven by functional traits

“…5c,f,i,l). These results agree with previous work showing that lichen tissue with higher nutrient content and lower secondary compounds promotes lichen decomposition and N release to the soil (Asplund & Wardle, 2013; Berdugo et al ., 2020).…”

“… to ), which typically has higher δ 15 N values (Moore, 1974). Lower C : N ratios have been related to increased decomposition rates in terricolous lichens and mosses and to N release in mosses (Limpens & Berendse, 2003; Berdugo et al ., 2020). In addition, higher thallus N content can increase lichen palatability for soil fauna (e.g.…”

“…Although little is known about the contribution of biocrust‐forming lichens as soil nutrient sources via decomposition in drylands, it is expected that these lichens will eventually be incorporated into the soil in the form of litter or after fragmentation and burial, enhancing soil fertility. Recently, a decomposition experiment using biocrust‐forming lichens found that lichen litter can decompose as fast as that from vascular plants, and that it loses C and N with time (Berdugo et al ., 2020). These findings suggest that nutrients present in lichen tissue can be transferred to the soil as a result of decomposition processes.…”

Moss mortality significantly altered topsoil multifunctionality and microbial networks in a temperate desert

“…Wang et al, 2015). Photodegradation of moss residues may improve soil TC, nitrogen, and phosphorus content (Berdugo et al, 2021). Meanwhile, the interactions between bacteria and fungi showed no significant variation after moss mortality, which may contribute to the decomposition of moss residues and, as a result, promote the increase of SMF combined with photodegradation (Figure 5e,f).…”