Total organic carbon concentrations in ecosystem solutions of a remote tropical montane forest respond to global environmental change

Abstract

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Characteristics of Dissolved Organic Matter and Dissolved Lignin Phenols in Tropical Forest Soil Solutions during Rainy Seasons and Their Responses to Nitrogen Deposition

“…DOM leaching from forest litter by rainwater is gradually transported and adsorbed into the deeper subsoil, which is considered an essential mechanism for the formation and stabilization of SOM in mineral soils that increase soil carbon sequestration. ,, However, this study showed that the concentration of DOC in the soil solution at 20 cm of mineral soil was not significantly higher than that at 40 cm (Figure ). This may be because of the sandy texture of the soils (Table S2) and weak adsorption of DOM in the 20–40 cm soil layer in this site.…”

“…The balance between the production and decomposition of DOM can contribute to dynamic DOC concentration fluctuations. The former mainly involves litter, microbial biomass, root exudates, decomposition, and/or desorption of SOM, and the latter includes DOM sorption, mineralization, and leaching. , In this study, the temperature increased gradually during the rainy season, probably leading to an increased DOM input from plant sources, such as plant litter and root exudates, and more decomposition from more active microorganisms. However, a study on Canadian forests found that increased temperature increased the carbon input and the CO 2 /DOC ratio, indicating that mineralization was relatively sensitive to temperature .…”

“…Additionally, root inputs (e.g., root exudates and necromass leachates) and desorption of soil organic matter (SOM) are critical belowground sources of DOM in the soil solution. In contrast, the DOM in soil solutions can be adsorbed or exchanged by soil particles, decomposed by extracellular enzymes, consumed by microbes, or leached out from the soil profile. − Thus, the concentrations and composition of DOM in soil solutions reflect the balance between production and decomposition (mainly driven by biological activity) and between adsorption and desorption (primarily determined by the soil type) …”

“…Indeed, in a recent study, it was found that 22 years of N addition increased the aromaticity and molecular size of DOM in soils of a temperate forest . Compared to temperate forests, tropical forests usually have much higher rainfall intensity and frequency, higher temperature, and more acidic soils that may alter the responses of the ecosystem elements (e.g., plant production and microbial biomass) to N deposition . While these elements regulate the DOM production and consumption, it is not known how DOM characteristics in tropical forest soil solutions would respond to N deposition during the rainy season.…”

Event Scale Relationships of DOC and TDN Fluxes in Throughfall and Stemflow Diverge From Stream Exports in a Forested Catchment

“…Further study of carbon and nitrogen fluxes from vegetation and streams during winter periods is warranted especially since stemflow solute fluxes are sensitive to winter meteorological event type (Levia, 2003). Wilcke et al (2020) reported a climate-related decrease in total organic carbon concentration in throughfall from 1998 to 2013 in a tropical montane forest while concentrations in stemflow increased over the same period suggesting that climate change may influence throughfall and stemflow differently. Thus, improved understanding of how throughfall, stemflow and stream solute export varies with precipitation event characteristics is critical to assessing the sensitivity of these ecologically important biogeochemical fluxes to climate forcing.…”