Interspecific variation in herbivory level and leaf nutrients of mangroves Rhizophora

Abstract

Trees and saplings of two mangrove species, Rhizophora stylosa Griff. and Rhizophora mucronata Lam. were observed in herbivory level (leaf damage area and percentage of herbivory) and leaf nutrients (total nitrogen, phosphorus, potassium, water content and deterrent tannin). We observed mangrove habitat located around Institut Teknologi Sepuluh November (ITS) Campus in Surabaya, East Java dominated by Rhizophora vegetation. Herbivorous insects showed an individual abundance of 15.15% of the total insects found in mangroves around the studied areas. Seedlings tended to be significantly higher in relative leaf damage and preferred by the herbivores than trees. One way ANOVA showed a non-significant difference in leaf area damage between two species (F=0.63, p-0.43; F=2.29; p-0.13). The concentration of leaf nutrients was significantly different between two species than habitus. Total nitrogen and water content in R. mucronata were significantly higher than in R. stylosa (F=5.10, p-0.03; F=142.13, p-<0.0001), whereas phosphorous and potassium (K) was significantly higher in R. stylosa than in R. mucronata (F=15.25, p-0.0002; F=75.916; p-<0.0001). Descriptively, R. stylosa leaves tended to be higher in deterrent tannins than R. mucronata, especially in seedling habitus. Leaf age, represented by plant habitus, is less to be related to high leaf palatability and insect herbivore nutrition than mangrove species.