Abstract
Aromatic plants show antimicrobial activity due to their essential oils, but their effect on litter decomposition is unclear. In this study, we evaluated the biomass loss and nutrient dynamics in leaf litters of two macrophytes (Miscanthus sacchariflorus and Carex brevicuspis) with and without addition of powdered material of the aromatic plant Polygonum hydropiper or the non-aromatic plant C. brevicuspis. The two powders had similar basic chemical qualities but P. hydropiperi had a higher essential oils concentration. Leaf litters of M. sacchariflorus and C. brevicuspis were incubated with powdered P. hydropiper or C. brevicuspis (500 g m−3, 250 g m−3, and no addition) for 120 days in a mesocosm experiment. Compared with the control (no addition), P. hydropiperi addition decelerated nutrient release and litter decomposition, while C. brevicuspis addition accelerated those processes. The nitrogen concentrations in both leaf litters and the phosphorus concentration in C. brevicuspis leaf litter were increased by addition of both plant powders. The fungal biomass in both leaf litters decreased after P. hydropiperi addition, due to the antifungal activity of its essential oils. These data indicate that the aromatic plant P. hydropiperi inhibits litter decomposition via its essential oils and that such inhibition is not species-specific.
Highlights
Litter decomposition partly controls the rates of nutrient and carbon cycles[1]
We tested the following hypotheses: first, that C. brevicuspis litter would decompose faster than M. sacchariflorus litter because of the high nutrient concentrations in C. brevicuspis; second, that the decomposition rates of both litters would be increased by C. brevicuspis addition due to the addition of exogenous nutrients; third, that the decomposition rates of both litters would be decreased by P. hydropiper addition due to its essential oils
The initial N, P, organic C, cellulose, and lignin concentrations differed significantly between the two litters (P < 0.05; Table 2). The concentrations of both N and P were higher in C. brevicuspis litter than in M. sacchariflorus litter (P < 0.05), while the initial lignin and cellulose concentrations, and C:N, C:P, and lignin:N were higher in M. sacchariflorus litter than in C. brevicuspis litter (P < 0.05)
Summary
Litter decomposition partly controls the rates of nutrient and carbon cycles[1]. The rate of litter decomposition is regulated by interacting physical, chemical, and biotic factors, such as climate (especially temperature and moisture), initial litter quality variables (e.g. nitrogen and phosphorus concentrations, lignin concentration, and carbon:N ratio), exogenous nutrient availability, and decomposers (microbes and invertebrates)[2,3]. Plants create different environments that retard or accelerate litter decomposition through negative or positive effects on the activity of organisms[4]. Aromatic plants are those that synthesize and emit essential oils. Because aromatic plants always coexist with other plant species, they might affect the decomposition of litter via the effects of their essential oils on microbes[6]. The objective of this study was to investigate the overall effect of P. hydropiper on the decomposition of leaf litter of Miscanthus sacchariflorus and Carex brevicuspis, two dominant plants at Dongting Lake, the second largest freshwater lake in China. We tested the following hypotheses: first, that C. brevicuspis litter would decompose faster than M. sacchariflorus litter because of the high nutrient concentrations in C. brevicuspis; second, that the decomposition rates of both litters would be increased by C. brevicuspis addition due to the addition of exogenous nutrients; third, that the decomposition rates of both litters would be decreased by P. hydropiper addition due to its essential oils
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