With the intensification of climate change, blue carbon ecosystems (such as mangroves, salt marshes, and seagrass beds) have become critical ecological barriers in mitigating climate change, storing carbon, and protecting biodiversity. However, blue carbon ecotones (BCEs) — transitional areas connecting land and marine ecosystems — are facing unprecedented environmental changes, making assessing their health a hot topic in global ecological research.
To fill this research gap, Jiaqi Zhang (PhD student) and Matteo Convertino (PI) of the fuTuRE EcoSystems (TREES) lab at Tsinghua Shenzhen International Graduate School’s Institute of Environment and Ecology, combined remote sensing information and ecological models to propose a novel health assessment framework for blue carbon ecotones. The proposed Benefit-Pressure-Transformation Risk model (BPT model) aligns with existing assessment models by not only assessing the risk of ecosystemic collapse but also focusing on the resilience and functionality of BCEs. This framework innovatively incorporated the concept of hypervolume overlap as a measure of the risk of transformation into the BPT model, providing a more comprehensive understanding of the health state of BCEs (Figure 1). Based on existing coastal variables at the pixel scale (1° latitude x 1° longitude globally), they assess the health status of BCEs (mangroves, salt marshes, and seagrasses), which is defined as the Ecosystem Health Index (EHI) (Figure 2).
Figure 1. Framework for calculating Ecosystem Health Index
Figure 2. Global map and latitudinal pattern of blue carbon ecotone EHI
The results showed that around 20% of BCEs are vulnerable globally. Specifically, with every 1° increase in latitude, the EHI values for mangroves, salt marshes, and seagrasses decrease linearly, proportionally to a factor of 0.007, 0.003, and 0.004, respectively. The research also found that improving the EHI of mangroves not only supports resilience but also enhances their carbon sink function (+68 Mg per hectare/0.1 EHI) and biodiversity, making ecosystem health a critical factor in climate change mitigation.
This study’s innovation lies in proposing a global-scale health assessment framework for blue carbon ecosystems. The BPT model, by combining the latest advances in ecology and remote sensing technology, achieves transdisciplinary integration. This research points out that habitat structure plays a more critical role in determining BCE health than environmental pressures, which not only underscores the importance of habitat structure in ecosystem health but also provides theoretical support and research directions for future ecosystem restoration and nature-based solutions.
The research findings were published in iScience under the title “Blueprinting the Ecosystem Health Index for Blue Carbon Ecotones”. The first author is Jiaqi Zhang, PhD student in Environmental Science and Engineering at Tsinghua University, and the corresponding author is Matteo Convertino.
This work was funded by Shenzhen Pengcheng Peacock Talents Funding (grant 020210320), Shenzhen Stability Support Grant (grant WDZC20231128160214001), Shenzhen Science and Technology Program for The Key Laboratory of Ecological Remediation and Carbon Sequestration at Tsinghua Shenzhen International Graduate School (grant ZDSYS20220606100806014), and Cross-disciplinary Program at Tsinghua Shenzhen International Graduate School (grant JC2024011).
Link to the full article: https://doi.org/10.1016/j.isci.2024.111426
Written by Jiaqi Zhang
Images by Jiaqi Zhang and Matteo Convertino
Edited by Huang Xiaojia
Reviewed by Chen Chaoqun
