Plant and Soil ( IF 3.9 ) Pub Date : 2021-08-24 , DOI: 10.1007/s11104-021-05134-1 Su-Li Li 1 , Zhi Zheng 1 , Yi-Dong Ding 1 , Jia-Wen Xu 1 , Rong Mao 1
Background and aims
Litter-derived dissolved organic carbon (DOC) biodegradation is critical to forest ecosystem structure and function. However, it is unclear whether mixing overstory and understory litter-derived DOC could produce non-additive effects on biodegradation in forests.
Methods
We extracted DOC from leaf litter of two coniferous trees, four broadleaf trees, and four understory ferns in subtropical forests and used a laboratory incubation method to measure pure and mixed overstory and understory litter-derived DOC biodegradation. The purposes were to assess the interspecific patterns of litter-derived DOC biodegradation between overstory trees and understory ferns, and then examine the non-additive effects of mixing overstory and understory litter-derived DOC on biodegradation.
Results
Litter-derived DOC biodegradation of understory ferns was comparable to that of overstory broadleaf trees, but higher than that of overstory coniferous trees. Mixing overstory and understory litter-derived DOC produced non-additive effects on biodegradation in all 24 DOC mixtures. Specifically, synergistic effects were observed in 22 DOC mixtures, and antagonistic effects occurred in the other two DOC mixtures. Non-additive effects on DOC biodegradation were positively related to the interspecific differences in DOC:dissolved total phosphorus ratio and DOC aromaticity, respectively, and exhibited no significant relationship with the interspecific differences in DOC:dissolved total nitrogen ratio.
Conclusions
Non-additive effects are common during microbial degradation of overstory and understory litter-derived DOC mixtures, and trait dissimilarity among component DOC sources drives the directions and magnitudes of non-additive effects on biodegradation in subtropical forests.