Phong Nguyen Tan, Thuan Nguyen Bao, Tien Nguyen Ngoc
Faculty of Environment and Labour Safety, Ton Duc Thang University, Ho Chi Minh City, Vietnam.
Institute of Marine Geology and Geophysics, Vietnam Academy of Science and Technology, Hanoi, Vietnam.
Life (Basel). 2025 Jan 21;15(2):136. doi: 10.3390/life15020136.
Although successful in protecting planted mangrove plants, the effectiveness of emergent detached offshore structures in increasing vegetation cover has yet to be definitively determined. We selected Tien Giang Province, Vietnam as an appropriate case study to address this question. We analyzed multiyear (2000 and 2022) shoreline changes and calculated the enhanced vegetation index (EVI) together with ground truthing in pursuit of the objectives of the study. Our findings suggest that emergent detached offshore structures have yet to lead to an increase in vegetation cover or promote mangrove growth. The vegetation growth steadily increased, as did the high level of natural mangrove growth with fully grown mangrove trees, even before the structures were constructed. By 2015, all the categories increased slightly except for low vegetation cover (LVC) and medium vegetation cover (MVC). LVC decreased from 390 ha in 2010 to 291 ha in 2015, while MVC decreased from 305 ha in 2010 to 275 ha in 2015. By 2020, all the categories decreased slightly except for non-vegetation cover-Barren lands (NVC2) and MVC. NVC2 decreased slightly from 404 ha in 2015 to 368 ha in 2015. The MVC decreased slightly from 275 ha in 2015 to 212 ha in 2020. Non-vegetation cover-Intertidal mudflats (NVC1)-LVC, and high vegetation cover (HVC) increased slightly from 2015 (326 ha, 291 ha, and 249 ha, respectively) to 2020 (368 ha, 292 ha, and 298 ha, respectively). By 2022, NVC2, MVC, and HVC remained unchanged, while NVC1 and LVC increased slightly from 368 ha and 292 ha in 2015, respectively, to 380 ha and 302 ha, respectively. The increase in vegetation cover and the natural regeneration of mangrove species were partly due to the adaptation of mangrove species to the site (river mouth areas), particularly the protection provided by Ngang Island offshore, and the construction of these structures. In addition, these structures were constructed in a rather stable area (slightly eroded and estuarine area) and therefore have yet to provide any noticeable benefits for mangrove regeneration three to five years after their construction. In the future, the morpho dynamic and hydrodynamic elements of the site should be adequately considered during the design and construction of these structures to increase vegetation cover and promote natural mangrove regeneration.
尽管在保护种植的红树林植物方面取得了成功，但离岸式独立新兴结构在增加植被覆盖方面的有效性尚未得到最终确定。我们选择越南的前江省作为一个合适的案例研究来解决这个问题。为了实现研究目标，我们分析了多年（2000年和2022年）的海岸线变化，并计算了增强植被指数（EVI），同时进行了实地调查。我们的研究结果表明，离岸式独立新兴结构尚未导致植被覆盖增加或促进红树林生长。即使在这些结构建成之前，植被生长也在稳步增加，天然红树林的生长水平也很高，有完全成熟的红树林树木。到2015年，除了低植被覆盖（LVC）和中等植被覆盖（MVC）外，所有类别都略有增加。LVC从2010年的390公顷减少到2015年的291公顷，而MVC从2010年的305公顷减少到2015年的275公顷。到2020年，除了非植被覆盖-裸地（NVC2）和MVC外，所有类别都略有下降。NVC2从2015年的404公顷略有减少到2015年的368公顷。MVC从2015年的275公顷略有减少到2020年的212公顷。非植被覆盖-潮间带泥滩（NVC1）-LVC和高植被覆盖（HVC）从2015年（分别为326公顷、291公顷和249公顷）到2020年（分别为368公顷、292公顷和298公顷）略有增加。到2022年，NVC2、MVC和HVC保持不变，而NVC1和LVC分别从2015年的368公顷和292公顷略有增加到380公顷和302公顷。植被覆盖的增加和红树林物种的自然再生部分归因于红树林物种对该地点（河口地区）的适应，特别是Ngang岛近海提供的保护以及这些结构的建设。此外，这些结构建在一个相当稳定的区域（略有侵蚀的河口区域），因此在建成三到五年后尚未为红树林再生带来任何明显益处。未来，在设计和建造这些结构时，应充分考虑该地点的地貌动力和水动力要素，以增加植被覆盖并促进天然红树林再生。
