Species identity of biocrust-forming lichens drives the response of soil nitrogen cycle to altered precipitation frequency and nitrogen amendment

Abstract

a b s t r a c tBiological soil crusts (biocrusts) are fundamental components of drylands worldwide, and are of great importance for the regulation of ecosystem functioning. However, little is known on the role of species identify of biocrust-forming lichens in mediating the response of nitrogen (N) cycling to concurring global environmental change. Here, we conducted a microcosm study to evaluate how the species identity of biocrust-forming lichens (Diploschistes thunbergianus, Psora crystallifera and Xanthoparmelia reptans) regulate key processes of N cycling in response to simulated changes in rainfall frequency and N addition. We explicitly considered both direct and indirect effects (i.e. driven via microbial diversity and abundance) of global changes on N availability and losses using structural equation models. Our results showed that species of biocrust-forming lichens differentially mediated effects of N amendment and altered rainfall frequencies on belowground nitrate availability and N 2 O flux rate. For instance, soils under P. crystallifera species showed the highest increase in nitrate content in response to N amendment under low rainfall frequency. Moreover, soils under D. thunbergianus showed the highest N 2 O flux under high rainfall frequency without N addition. Interestingly, soils under X. reptans showed lowest and highest resistance in nitrate availability and N 2 O flux, respectively, in response to N addition regardless of different rainfall frequencies. Strikingly, we only found an indirect impact of either rainfall frequency or N amendment on the nitrate availability (but not N 2 O flux) driven via the ammonia-oxidizing community under X. reptans. Our results provide evidence that the species identity of biocrust-forming lichens modulates the response of N cycling to global change drivers. These findings have implications for predicting the potential consequence of altered rainfall patterns and environmental N inputs in dryland ecosystems.

Biocrust‐forming mosses mitigate the impact of aridity on soil microbial communities in drylands: observational evidence from three continents

“…The sign (positive) of the effects of mosses on microbial stability reported here might be shared across other biocrust types such as lichens, have been previously reported to promote both soil microbial activity and functioning previously (Liu et al ., ). However, it is also probable that the magnitude of the positive effects from biocrusts on soil microbial stability are dependent upon the identity of biocrusts, as recent studies point to species‐specific effects on soil functions and microbial abundance in biocrust communities (Delgado‐Baquerizo et al ., ; Liu et al ., ).…”

“…Finally, we clarify that our approach explicitly assumes that naturally occurring patches of bare ground and biocrusts are the drivers of microsite amelioration rather than reflecting pre‐existing conditions. Such an assumption is supported by previous experimental studies providing evidence that biocrusts modulate the response of soil microbes and microbially driven functions to global change drivers (Reed et al ., ; Delgado‐Baquerizo et al ., ; Liu et al ., , ).…”

Microbial nitrous oxide emissions in dryland ecosystems: mechanisms, microbiome and mitigation

“…Drylands are highly heterogeneous ecosystems characterized by a sparse distribution of plants, which are separated by open areas often covered by biocrusts and inhabited by soil arthropods (Delgado-Baquerizo et al, 2016a). Biocrusts are surface components typical of natural drylands, and constitute bacteria, fungi, algae, lichens and mosses that are of great importance for the regulation of N cycling processes (Delgado-Baquerizo et al, 2014;Liu et al, 2016). These biotic attributes and their interactions have unique effects on N-cycling microorganisms and ecosystem functioning in drylands (Delgado-Baquerizo et al, 2016a) due to their ability to capture and cycle water and nutrients and attract a variety of microbiota (Maestre et al, 2016).…”

Intraspecies variation in a widely distributed tree species regulates the responses of soil microbiome to different temperature regimes

“…Also, recent studies provide evidence that two genotypes of the same species (domesticated plants and their wild relatives) can influence ecosystem function (Delgado-Baquerizo et al, 2016a) and microbial communities (Garcia-Palacios et al, 2013;Leff et al, 2017). Species identity of plants and lichens are known to play an important role in regulating responses of soil microbial community and ecosystem functions to global climate factors, including increasing temperature, nitrogen deposition and changes in water availability, mainly through root exudation or altered microclimate (Haichar et al, 2008;Liu et al, 2016;Yuan et al, 2016). Previous studies suggested that there was intraspecies variation in plant response to climate change including elevated CO 2 and warming via altered traits such as photosynthetic capacity, leaf area and growth (Drake et al, 2015;Huang et al, 2015).…”