The mangrove ecosystem in a harbor-impacted city in Dumai, Indonesia: A conservation status

Abstract

The city of Dumai has mangrove resources in various conditions due to the presence of industry in the area. This study aims to analyze the conservation status of the vegetation structure and to study the spatial variability and the interaction of mangrove vegetation environmental parameters on the coast of the city of Dumai. The study was conducted at ten observation stations, with the study area divided into three parts. Data were obtained by measuring line transects and establishing 10 m × 10 m sample plots, while environmental parameters were measured in situ and ex situ. The mangrove vegetation and structure were examined based on their ecological indices. The comparison between diversity indices was analyzed by analysis of variance (ANOVA). Mangrove species that were differentiated between sections were analyzed using similarity of percentage (SIMPER), and environmental factors affecting vegetation and mangrove structure were analyzed based on principal component analysis (PCA). The species identification results revealed 13 species, including Avicennia lanata, that are classified as vulnerable globally. Based on the importance value index (IVI), Rhizophora apiculata, Xylocarpus granatum, Sonneratia alba and Avicennia alba were identified as the most important species. The ecological index showed that the mangrove diversity is low (01.06–01.90) with an even distribution (00.41–01.00). The mangrove density varied from 00.79 to 570.87 individuals/ha, and the basal area ranged from 00.00–08.99 m2/ha. The maturity index showed that station VIII had a high maturity level (80.56), followed by Stations X, IX and IV (77.08, 72.22 and 53.70, respectively). Between the north and south and between the south and center, S. alba was the distinguishing species (25.19% and 15.45% dissimilarity), while in the north and central areas, R. apiculata was found to be a differentiating species (22.70% dissimilarity). The environmental condition parameters showed a strong relationship to the density and basal level of the mangrove areas.