PS 40-93 - Influence of Environmental Conditions on Litterfall Flux and n-Alkane Dynamics in Nanjenshan Tropical Forest, Southernmost Taiwan

Abstract: Understanding the impact of environment on carbon storage and release in forest ecosystems is crucial for ecosystem management. This study investigates the influence of heterogenous environment on litterfall flux and n-Alkane dynamics in the Nanjenshan tropical forest. Nanjenshan is characterized by its high topographic heterogeneity, shaped by typhoons and northeast monsoon winds. The n-Alkanes present in the litterfall serve as valuable biomarkers. To assess litterfall production under different environment, we collected litterfall from 22 systematically placed traps in the Nanjenshan on a monthly basis from October 2012 to September 2013. The traps were positioned in areas with varying wind exposures, including the ravine habitat (low wind exposure) and the windward and leeward habitats (high wind exposure). The collected litterfall was categorized into different portions, including litter-leaves, flowers, fruits, branches, and miscellaneous items. We then extracted n-Alkanes from the litter-leaf and quantified their concentrations. By combining the n-Alkane concentrations with the monthly weights of the samples, we calculated the n-Alkane flux for each portion on a monthly basis. Furthermore, an analysis of variance was conducted to evaluate the significance of litterfall flux and n-Alkane dynamics across different portions, habitats, and time periods.



Our results indicate that the mean annual litterfall flux over the study period was 7.02±2.47 Mg ha^-1yr^-1. Specifically, the ravine habitat exhibited a higher litterfall flux (8.32±2.31 Mg ha^-1yr^-1), whereas the windward and leeward habitats displayed lower fluxes (5.54±1.83 Mg ha^-1yr^-1 and 5.34±1.63 Mg ha^-1yr^-1, respectively). Litter-leaf species accounted for the majority (60%) of the total litterfall flux in the Nanjenshan. In terms of n-Alkane flux, the ravine habitat demonstrated higher concentrations (2.70±0.23 Mg ha^-1yr^-1), whereas the windward and leeward habitats exhibited lower concentrations (1.26±0.17 Mg ha^-1yr^-1 and 1.10±0.07 Mg ha^-1yr^-1, respectively). The n-Alkanes primarily consisted of C₂₉, C₃₁, and C₃₃ compounds. Our findings highlight that species from the ravine habitat contribute significantly to litter-leaf and exhibit higher n-Alkane concentrations. This suggests that habitats characterized by flat, high moisture, and low wind exposure have a greater carbon accumulation rate compared to habitats with higher wind impact.



In conclusion, this study emphasizes the influence of environmental conditions on litterfall flux and n-Alkane dynamics in the Nanjenshan. Our findings provide valuable insights into the carbon input into the ecosystem, highlighting the role of litterfall and n-Alkanes in carbon storage and release. These findings contribute to the broader understanding of forest ecosystem dynamics and have important implications for forest management strategies.