4:10 PM - 4:25 PM
[ACG51-09] Interactions between topography, tides, and tree distribution in mangrove forests of the Ryukyu Islands
Keywords:mangrove, LiDAR, tide, numerical simulation
Mangrove ecosystems, which develop in tropical and subtropical areas within the upper intertidal zone, are known to exhibit zonation patterns where dominant tree species shift in response to topographic changes. Previous studies have pointed out that rainfall, tides, coastal surges, and river flows influence the distribution of mangrove ecosystems. These factors may also be influenced by microtopography in these areas. However, the interactions between microtopography and the development of mangrove ecosystems have not yet been fully investigated.
This knowledge gap has led to numerous failures in mangrove reforestation and maintenance efforts, often due to inadequate site selection (Lewis, 2005). Thus, obtaining high-resolution spatial data on microtopography and tree distribution over a wide area is crucial for understanding the factors influencing mangrove ecosystem distribution.
This study focuses on mangrove forests in the Ryukyu Islands, aiming to quantitatively compare tree species distribution and microtopography across multiple sites to elucidate the interactions between mangrove tree species and microtopography. To achieve this, two types of LiDAR (Light Detection and Ranging) surveys, ALS (Airborne Laser Scanning) and MLS (Mobile Laser Scanning), were employed to generate 3D representations of the forest environment (Kasai et al., 2024). Additionally, given the critical role of tidal flows in regulating the distribution of mangrove ecosystems, a year-long tidal simulation was conducted with Delft3D to model tidal flow within the forest. The numerical simulations were analyzed to assess how microtopography influences tidal movement within the forest and how tree distribution is regulated by tidal conditions.
Comparing LiDAR surveys conducted across various sites in the Ryukyu Islands revealed regional variations in the modal elevation and elevation range of mangrove habitat distribution. By quantitatively characterizing tree distribution based on microtopography at the scale of thousands of individual trees, this study provides a foundation for studies into the topographic determinants of mangrove distribution.
The high-resolution tidal simulations enabled by detailed topographic and tree distribution data significantly enhanced the spatial local tidal flow modeling influenced by local microtopography compared to conventional approaches. Furthermore, the results demonstrated how tidal constraints influence the spatial extent of mangrove forests.
By combining high-resolution data on tree distribution and microtopography with numerical simulations, this study provides new insights into the factors that affect mangrove growth. It also helps explain regional differences in mangrove distribution. Future research using such detailed data is expected to improve our understanding of how mangrove ecosystems form and adapt to environmental changes.
This knowledge gap has led to numerous failures in mangrove reforestation and maintenance efforts, often due to inadequate site selection (Lewis, 2005). Thus, obtaining high-resolution spatial data on microtopography and tree distribution over a wide area is crucial for understanding the factors influencing mangrove ecosystem distribution.
This study focuses on mangrove forests in the Ryukyu Islands, aiming to quantitatively compare tree species distribution and microtopography across multiple sites to elucidate the interactions between mangrove tree species and microtopography. To achieve this, two types of LiDAR (Light Detection and Ranging) surveys, ALS (Airborne Laser Scanning) and MLS (Mobile Laser Scanning), were employed to generate 3D representations of the forest environment (Kasai et al., 2024). Additionally, given the critical role of tidal flows in regulating the distribution of mangrove ecosystems, a year-long tidal simulation was conducted with Delft3D to model tidal flow within the forest. The numerical simulations were analyzed to assess how microtopography influences tidal movement within the forest and how tree distribution is regulated by tidal conditions.
Comparing LiDAR surveys conducted across various sites in the Ryukyu Islands revealed regional variations in the modal elevation and elevation range of mangrove habitat distribution. By quantitatively characterizing tree distribution based on microtopography at the scale of thousands of individual trees, this study provides a foundation for studies into the topographic determinants of mangrove distribution.
The high-resolution tidal simulations enabled by detailed topographic and tree distribution data significantly enhanced the spatial local tidal flow modeling influenced by local microtopography compared to conventional approaches. Furthermore, the results demonstrated how tidal constraints influence the spatial extent of mangrove forests.
By combining high-resolution data on tree distribution and microtopography with numerical simulations, this study provides new insights into the factors that affect mangrove growth. It also helps explain regional differences in mangrove distribution. Future research using such detailed data is expected to improve our understanding of how mangrove ecosystems form and adapt to environmental changes.