Soil microbial diversity drives the priming effect along climate gradients: a case study in Madagascar

Abstract

The priming effect in soil is proposed to be generated by two distinct mechanisms: 'stoichiometric decomposition' and/or 'nutrient mining' theories. Each mechanism has its own dynamics, involves its own microbial actors, and targets different soil organic matter (SOM) pools. The present study aims to evaluate how climatic parameters drive the intensity of each priming effect generation mechanism via the modification of soil microbial and physicochemical properties. Soils were sampled in the center of Madagascar, along climatic gradients designed to distinguish temperature from rainfall effects. Abiotic and biotic soil descriptors were characterized including bacterial and fungal phylogenetic composition. Potential organic matter mineralization and PE were assessed 7 and 42 days after the beginning of incubation with C-enriched wheat straw. Both priming mechanisms were mainly driven by the mean annual temperature but in opposite directions. The priming effect generated by stoichiometric decomposition was fostered under colder climates, because of soil enrichment in less developed organic matter, as well as in fast-growing populations. Conversely, the priming effect generated by nutrient mining was enhanced under warmer climates, probably because of the lack of competition between slow-growing populations mining SOM and fast-growing populations for the energy-rich residue entering the soil. Our study leads to hypotheses about the consequences of climate change on both PE generation mechanisms and associated consequences on soil carbon sequestration.

High Microbial Diversity Promotes Soil Ecosystem Functioning

“…In another respect, our results show that the priming effect decreased with the decrease in microbial diversity. Again, this is not in agreement with the food web hypothesis since a decrease in macronutrient availability would, on the contrary, have increased the intensity of the PE due to stimulation of the nutrientmining mechanism (44,50,51) that has been demonstrated to take place in cases of nutrient depletion. Finally, the hypothesis of a decrease of nutrient availability is not in agreement with the decrease of the decomposition of lignin following the erosion of diversity previously reported in the context of the same experiment (16).…”

Analysis of microbial utilization of rice straw in paddy soil using a DNA‐SIP approach

“…Pseudomonas species in Gammaproteobacteria, known to degrade a wide variety of organic compounds and generally associated with lignocellulose degradation (Cheng & Chang, 2011;Mohana, Shah, Divecha, & Madamwar, 2008), were the main C utilizers at Day 90. Some subgroups of Proteobacteria can decompose poorly decayed plant tissues, and so they are also able to survive in labile C-exhausted conditions at late decomposition stage (Razanamalala, Razafimbelo, Maron, Ranjard, & Chemidlin, 2018). Rime, Hartmann, Stierli, Anesio, and Frey (2016) studied the microbial community in response to increasing vegetation under various C sources and found different fungal taxa played roles in C decomposition.…”

Deciphering Linkages Between Microbial Communities and Priming Effects in Lake Sediments With Different Salinity

“…Furthermore, the changes of prokaryotic and fungal community compositions owing to glucose addition may suggest that both prokaryotes and fungi may drive positive PEs in the studied lake sediment microcosms. Multiple previous studies have characterized bacterial roles in driving positive PEs (Mau et al, 2015;Morrissey et al, 2017;Razanamalala et al, 2017Razanamalala et al, , 2018. However, little attention has been given to the importance of fungi in positive PEs, especially in lake sediments (Fan et al, 2019;Fontaine et al, 2011).…”

“…Several studies pointed out that both stoichiometric decomposition and nutrient mining processes can co‐occur in one sample, and they are regulated by environmental factors (e.g., nutrient status and temperature) during positive PEs in soil ecosystems (Chen et al, 2014; Razanamalala et al, 2018). For example, the former process is favored at the condition of rich nutrients or low temperature, while the latter prefers the condition of nutrient limitation or high temperature (Chen et al, 2014; Razanamalala et al, 2017). However, little is known whether salinity, one type of environmental determinant, can affect PE generation processes.…”