Litter quality and site characteristics interact to affect the response of priming effect to temperature in subtropical forests

Abstract

Forest litter inputs to soil can stimulate the decomposition of older soil organic matter (SOM) via a priming effect (PE). The magnitude and underlying mechanisms driving PE are poorly understood, with especially little know about how litter quality and site conditions affect PE in situ. Further, very few studies have examined PE in tropical and subtropical soils. Here, we established low and high elevation sites (600 vs. 1,400 m a.s.l.) in the subtropical Wuyishan National Park, China, that differed with respect to mean annual temperature (MAT; ∆MAT = 4.2°C), vegetation, soil texture and soil moisture. We conducted a 1‐year field incubation study at these two sites to compare PE induced by adding low‐ and high‐quality 13C‐labelled leaf litter to soils. At the low elevation site, additions of high‐quality (low C/N) litter caused a PE that was 140% greater than the PE observed following additions of low‐quality (high C/N) litter. In contrast, we saw no significant differences in PE between litter types at the high elevation site, perhaps because PE was not limited by substrate quality at this cooler, finer textured and higher soil moisture coniferous site. In addition, we found a negative relationship between home‐field advantage (HFA) for litter decomposition and PE, indicating that specialized litter decomposer community driving HFA may not accelerate SOM decomposition via PE in the same way. In line with our observed strong relationship between PE and the efficiency of priming (PE size per unit of mineralized litter C), PEs induced by the high‐ and low‐quality litters were directed to microbial phosphorus (P) mining rather than nitrogen (N) mining. This interpretation aligns with observed increases in the activity of P acquiring extracellular enzymes, often described as phosphatases (P‐tases), as well as the positive relationship between the PE, P‐tase activity and the activity of C acquiring extracellular enzymes. Overall, this PE study across two contrasting sites highlights the important role of site characteristics and litter quality in regulating PE size. Further, we suggest that MAT may be a dominant driver of soil priming, through both the direct effects of litter quantity on labile substrate supply and the indirect effects of litter quality changes on downstream decomposer communities. A free Plain Language Summary can be found within the Supporting Information of this article.

Nitrogen-Induced Changes in Soil Environmental Factors Are More Important Than Nitrification and Denitrification Gene Abundance in Regulating N2O Emissions in Subtropical Forest Soils

“…and 1,100 m a.s.l., respectively. While Castanopsis carlesii Hay and Castanopsis eyrie Tutch are the dominant species in the BF, Pinus taiwanensis Hayata is the dominant species in the PF ( Xu et al, 2010 ; Lyu et al, 2019 ). Background atmospheric N deposition in the WNNR is about 8 kg N ha –1 year –1 ( Xu et al, 2016 ; Gurmesa et al, 2022 ).…”

“…The second sub-sample was air-dried for the measurements of soil chemical properties. The soil at both sites is classified as yellow-red soil based on the Chinese Soil Classification System, equivalent to an Ultisol according to the United States Department of Agriculture Soil Taxonomy classification system ( Lyu et al, 2019 ). Soil chemical properties were shown in Table 1 .…”

Long-term bare fallow soil reveals the temperature sensitivity of priming effect of the relatively stabilized soil organic matter

“…a mixture of the relatively stabilized and labile SOM pools). Moreover, the absence of an adequate understanding on the PE of the relatively stabilized SOM leads to a debate on the temperature sensitivity of PE (Ghee et al, 2013;Frøseth and Bleken, 2015;Lyu et al, 2019).…”

The Response of Critical Microbial Taxa to Litter Micro-Nutrients and Macro-Chemistry Determined the Agricultural Soil Priming Intensity After Afforestation

“…For example, the Microbial Efficiency-Matrix Stabilization (MEMS) hypothesis states that litters with high N and low lignin content contribute to significant soil organic matter stabilization in the mineral soil matrix ( Cotrufo et al, 2013 ). This has recently been challenged by studies demonstrating that high-quality substrate (high N/lignin) is expected to prime the loss of the original carbon source more efficiently than of the added one ( Blagodatskaya et al, 2014 ; Lyu et al, 2019 ). To some extent, this inconsistency can be attributed to the fact that most of the research on litter quality did not include micro chemical compounds, such as tannins ( Shahbaz et al, 2018 ; Sun et al, 2019 ).…”