Abstract
While litter decomposition is a fundamental ecological process, previous studies have mainly focused on the decay of single species. In this study, we conducted a litter-mixing experiment to investigate litter diversity effects on greenhouse gas (GHG) emissions from an alpine steppe soil in Northern Tibet. Significant non-additive effects of litter diversity on GHG dynamics can be detected; these non-additive effects were the result of species composition rather than species richness. Synergistic effects were frequent for CO2 and N2O emissions, as they were found to occur in 70.5% and 47.1% of total cases, respectively; antagonistic effects on CH4 uptake predominated in 60.3% of the cases examined. The degree of synergism and antagonism may be significantly impacted by litter chemical traits, such as lignin and N, lignin:N ratio, and total phenols during decomposition (P < 0.05). In addition, the relationship between chemical traits and litter-mixing effects changed over incubation time. Our study provides an opportunity to gain insight into the relationship between litter diversity and soil ecological processes. The results indicate that higher plant diversity may generally enhance CO2 and N2O emissions while inhibiting CH4 uptake; meanwhile, the direction and strength of non-additive effects appear to be related to litter chemical traits.
Highlights
Effects of litter-mixing on decomposition rate were unpredictable, because additive and non-additive effects were observed, and non-additivity seemed to be predominant[2,9,11,12]
The cumulative CO2 emission was highest in S. purpurea (SP)+ C. moorcroftii (CM)+ Leontopodium pusillum (Beauv.) Hand.-Mazz. (LP)+ AN treatment and lowest in SP+ LP treatment, with values of 1246.86 ± 29.21 mg-C kg soil−1 and 804.56 ± 22.01 mg-C kg soil−1
The cumulative N2O emission was highest in CM+ LP+ AN treatment and lowest in SP+ LP+ AN treatment, with values of 82.27 ± 1.79 μ g-N kg soil−1 and 57.66 ± 4.64 μ g-N kg soil−1, respectively
Summary
Effects of litter-mixing on decomposition rate were unpredictable, because additive and non-additive (synergistic and antagonistic) effects were observed, and non-additivity seemed to be predominant[2,9,11,12]. Mixed litters from species with varying resource quality and structure change the chemical environment and physically alter the total litter surface where decomposition is occurring[13,14]. These alterations can affect soil ecological processes such as soil respiration, net N mineralization, and microbial activity. The aim of our work was to (1) investigate the effects of plant litter additions from the alpine steppe soil in Northern Tibet on GHG (CO2, CH4, and N2O) emissions; and (2) test the effects of litter species diversity (richness and composition) on soil GHG emissions during decomposition
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