Status Review of Guinayangan Quezon Mangrove Forest: An Assessment of Species Diversity and Habitat Analysis

Abstract

This study was conducted to determine the status of the Mangrove Walk located in Brgy. Calimpak, Guinayangan, Quezon. Three main procedures were undertaken: species identification; habitat analysis using percent crown cover, regeneration per m², and average height; and the computation of diversity indicators such as species richness, relative abundance, Shannon–Wiener diversity index, and species evenness using PAST software. A total of 183 mangrove trees were recorded across three transect lines and two quadrats. Seven (7) out of the 23 mangrove species listed by the Zoological Society of London (ZSL) for the Municipality of Guinayangan, Quezon were identified at the study site, representing three families: Acanthaceae, Lythraceae, and Rhizophoraceae. In the habitat analysis using the parameters by Deguit et al. (2004), the results showed that the average percent crown cover of 5.63 falls under the poor condition category, as it lies within the 0–25% crown cover range. The average tree height of 9.04 meters is classified as excellent, as it exceeds the 5-meter threshold. For regeneration density, the computed value of 0.83 individuals per m² is considered good, as it falls within the range of 0.7 to less than 1 individual per m². In terms of diversity indices, relative abundance across all sampling stations showed that the dominant species were Sonneratia alba (39%), Avicennia marina (16.5%), and Rhizophora mucronata together with Sonneratia apetala (11.0%). Sonneratia alba was observed to dominate all three transects and two quadrats. In contrast, species with lower relative abundance included Bruguiera cylindrica (9.9%), Bruguiera parviflora (9.9%), and Rhizophora apiculata (2.7%). In terms of species richness, Transect Lines 1 and 3 recorded the highest values with seven species each, followed by Transect Line 2 with six species. Quadrats 1 and 2 recorded the lowest species richness, each with five species. For the Shannon–Wiener diversity index, Transect Line 3 obtained the highest value (1.83), followed by Transect Line 2 (1.71), Transect Line 1 (1.64), Quadrat 1 (1.43), and Quadrat 2 (1.42). Based on the interpretation scale, all transects, and quadrats exhibited a poor Shannon–Wiener diversity status. However, species evenness across all sampling units was balanced. In terms of species richness, all sampling units recorded values above five, indicating an integrated mangrove community structure.