Mangrove Forest Landcover Changes in Coastal Vietnam: A Case Study from 1973 to 2020 in Thanh Hoa and Nghe An Provinces

Mangrove forests can ameliorate the impacts of typhoons and storms, but their extent is threatened by coastal development. The northern coast of Vietnam is especially vulnerable as typhoons frequently hit it during the monsoon season. However, temporal change information in mangrove cover distribution in this region is incomplete. Therefore, this study was undertaken to detect change in the spatial distribution of mangroves in Thanh Hoa and Nghe An provinces and identify reasons for the cover change. Landsat satellite images from 1973 to 2020 were analyzed using the NDVI method combined with visual interpretation to detect mangrove area change. Six LULC classes were categorized: mangrove forest, other forests, aquaculture, other land use, mudflat, and water. The mangrove cover in Nghe An province was estimated to be 66.5 ha in 1973 and increased to 323.0 ha in 2020. Mangrove cover in Thanh Hoa province was 366.1 ha in 1973, decreased to 61.7 ha in 1995, and rose to 791.1 ha in 2020. Aquaculture was the main reason for the loss of mangroves in both provinces. Overall, the percentage of mangrove loss from aquaculture was 42.5% for Nghe An province and 60.1% for Thanh Hoa province. Mangrove restoration efforts have contributed significantly to mangrove cover, with more than 1300 ha being planted by 2020. This study reveals that improving mangrove restoration success remains a challenge for these provinces, and further refinement of engineering techniques is needed to improve restoration outcomes.

1. Introduction

2. Materials and Methods

2.1. Study Area

2.2. Image Selection

2.3. Data Pre-Processing

2.4. Land Cover Classification

2.5. Accuracy Assessment

3. Results

3.1. Classification and Accuracy Assessment

3.2. LULC Changes in Thanh Hoa and Nghe An Provinces from 1973 to 2020

3.3. Change in Mangrove Cover at the District Level from 1973 to 2020

3.4. Drivers of Change in Mangrove Cover

4. Discussion

4.1. Mangrove Extent

4.2. Drivers of Change Over Time

5. Conclusions

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► See detail:  Mangrove Forest Landcover Changes in Coastal Vietnam: A Case Study from 1973 to 2020 in Thanh Hoa and Nghe An Provinces

Huong Thi Thuy Nguyen 1,2,*, Giles E. S. Hardy 1 , Tuat Van Le 3, Huy Quoc Nguyen 3, Hoang Huy Nguyen 2, Thinh Van Nguyen 2 and Bernard Dell 1,4





1 Agriculture and Forest Sciences, Murdoch University, Murdoch 6150, Australia; G.Hardy@murdoch.edu.au (G.E.S.H.); B.Dell@murdoch.edu.au (B.D.)
2 Silviculture Research Institute, Vietnamese Academy of Forest Sciences, Duc Thang, Bac Tu Liem, Ha Noi 11910, Vietnam; nguyenhuyhoangvfu@gmail.com (H.H.N.); nguyenthinhfsiv@gmail.com (T.V.N.)
3 Institute of Ecology and Works Protection, Vietnam Academy for Water Resources, 267 Chua Boc, Dong Da, Ha Noi 11910, Vietnam; tuatwip@gmail.com (T.V.L.); huy_ctcr@yahoo.com (H.Q.N.)
4 Forest Protection Research Centre, Vietnamese Academy of Forest Sciences, Duc Thang, Bac Tu Liem, Ha Noi 11910, Vietnam
* Correspondence: huong.nguyen@murdoch.edu.au; Tel.: +84-977-795-206

Forests 2021, 12, 637. https://doi.org/10.3390/f12050637                                                     https://www.mdpi.com/journal/forests