Light availability controls rhizosphere priming effect of temperate forest trees. (September 2020)

• Record Type: Journal Article
• Authors: Chang, Qing; Qu, Guifang; Xu, Wenhua; Wang, Chao; Cheng, Weixin; Bai, Edith
• Is Part Of: Soil biology and biochemistry. Volume 148(2020)
• Publication Date: 2020-09
• Subjects: Rhizosphere priming effect -- Shading -- SOC decomposition -- Microbes -- Enzyme activity; Soil biochemistry -- Periodicals; Soil biology -- Periodicals; Sols -- Biochimie -- Périodiques; Sols -- Biologie -- Périodiques; Sols -- Microbiologie -- Périodiques; Bodembiologie; Biochemie; 631.46
• DOI: 10.1016/j.soilbio.2020.107895
• Languages: English
• ISSNs: 0038-0717

Abstract

Abstract: Plant can accelerate or slow down the soil organic carbon (SOC) decomposition by the rhizosphere priming effect (RPE). In forest ecosystems, the change of light availability due to canopy gap formation strongly influences growth of young trees and rhizosphere microbial activities in soil. However, the responses of RPE of forest young trees to light availability and its driving mechanisms remain elusive. We investigated the effects of about 60% shading on RPE of two dominant forest tree species (i.e., shade-tolerant species maple and photophilic species oak) over the four months of the growing season using the 13 C natural tracer approach. Our results showed that the effects of shading on RPE were not dependent on the tree species. Under natural light, negative RPE on SOC decomposition prevailed during the experimental period (The loss of soil carbon via CO2 was 31.9% lower in planted soil than in unplanted soil). RPE under shading was 71.1% more positive than that under natural light. Under natural light mineral nitrogen (N) content and microbial biomass nitrogen (MBN) were lower in planted soil than in unplanted soil, suggesting that N competition between roots and microbes due to N uptake by plants may be responsible for the negative RPE. The results of two-way ANOVA showed that although shading only had the tendency of increasing MBC, it significantly increased MBN and C-acquiring enzyme activities. These changes contributed to more positive RPE under shading. The main reason for this result may be the alleviation of root-microbes competition, the higher demand of available substrates from SOC by microbes and the higher soil moisture conditions under shading. Our study also highlights the importance of soil microbial biomass and enzyme activity when studying the mechanisms of the responses of RPE to shading or other environmental changes. Highlights: Under natural light negative RPE of maple and oak prevailed over the growing season. Competition between roots and microbes for N may be responsible for the negative RPE. Shading caused more positive RPE of maple and oak than natural light conditions. The increase of soil enzyme activities after shading led to more positive RPE.