Abstract
Simple SummaryThis research focuses on the leaching and decomposition of riparian zone plants, which lose mass and release nutrients due to changing water levels during their vigorous growth period. While different factors greatly influence litter decomposition, the change in soil characteristics over various depths and their relationship to litter are largely unknown in mega-reservoir settings. Current research explores how annual plants decompose and release nutrients while they are submerged in soggy circumstances. Flooding circumstances can hasten plant mass loss and nutrient release, as well as change soil and water characteristics. This research found that sediment hindered the loss of mass and C, N, and P elements while stimulating the release of the K element. The litter decomposition of annual herbaceous plants has minimal impact on the overall amount of carbon and nutrients in the soil when the soil is saturated with water. This is linked to water leaching and soil element transformation. However, this does not imply that the significance of litter for soil nutrition is minor. It is essential to investigate the continuing production of residual soil litter nutrients after the water level has receded.Litter decomposition is an important soil nutrient source that promotes vegetation in deteriorated riparian zones worldwide. The periodic submergence and sediment burial effects on two prominent annual herbaceous plants (Echinochloa crusgali and Bidens tripartite) are little known in mega-reservoir settings. Our study focuses on the mass and carbon loss and nutrient release from E. crusgali and B. tripartitle litter and changes in soil properties, which are important for riparian zone rehabilitation in the Three Gorges Dam Reservoir, China. This study adopted the litter bag method to explore the nutrient change characteristics and changes in soil properties at different sediment burial depths under flooding scenarios. Three burial depths (0 cm, 5 cm, and 10 cm) were used for these two plants, and the experiment lasted for 180 days. The results revealed that the litter decay rate was high at first in the incubation experiment, and the nutrient loss rate followed the pattern of K > P > N > C. The relationship between % C remaining and % mass remaining was nearly 1:1, and the total amount of P exhibited a leaching–enrichment–release state in the decomposition process. Nutrients were changed significantly in the soil and overlying water at the first decomposition stage. Still, the total soil nutrient change was insignificant at the end, except for the 10 cm burial of B. tripartitle. Moreover, oxidation–reduction potential was the main factor in the litter decomposition process at different burial depths. This study indicated that sediment deposition reduced litter mass loss, slowed down the release of N and P, and retained more C, but promoted the release of K. Conclusively, in litter decomposition under waterlogging, the total soil nutrient content changed little. However, litter does more to the soil than that. Therefore, it is necessary to study the residual soil litter’s continuous output after the water level declines for restoration purposes.
Highlights
Litter decomposition is a fundamental component in any ecosystem cycle [1,2], which plays an important role in controlling nutrient transfer within and between aquatic and terrestrial environments [3]
Burial depths of sediment, times, and interactions significantly affected the nutrient release of litter decomposition
C, N, P, and K content decreased in the overall decomposition process of two annual herbaceous plants (E. crusgali and B. tripartita) at different burial depths
Summary
Litter decomposition is a fundamental component in any ecosystem cycle [1,2], which plays an important role in controlling nutrient transfer within and between aquatic and terrestrial environments [3]. Nutrient elements, such as N, P, K, Ca, and Mg, are released in litter decomposition. Temperature changes the mass loss and nutrient release rate of litter by affecting the activity of microbial decomposers [13,14]. Changes in the environment may have a significant impact on litter mass and nutrient loss [12]. Previous research has shown that the initial litter decomposition rate is accelerated in underwater flooding conditions due to the rapid loss of soluble substances, such as K element, by flushing, leaching, and collecting aquatic fungi. Little research has been conducted on annual herbaceous plants, which are characterized by dry–wet alternations [13]
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