Human Hydrographical Changes Interact with Propagule Predation Behaviour in Sri Lankan Mangrove Forests

Background

This article describes the relation between propagule predators and vegetation structure and environmental factors on a forest path. It also considers how human influence affects these interactions.

Research Goals & Methods

In mangrove forest patches, predation by crabs, snails, insects and mammals on propagules of A. officinalis, B. gymnorrhiza, R. apiculata and R. mucronata was monitored in a total of 24 experimental plots (3 per forest patch) and related to environmental factors such as topography, water level, rainfall, and season. Rainfall data were collected for the period 1948–1999 and used to study the relationship between lagoon water level and rainfall with propagule predation and dispersion before and after the construction of a raised path and dam.

Conclusions & Takeaways

The authors concluded that propagule predation by grapsid crabs and snails is not an occasional phenomenon; the micro-topography and the local individual crab intensity plays a role in many of the observed differences among species and forest patches. Extrapolation to past conditions indicates that the impact of dam construction was great enough to decrease the number of months with flooding. The importance of spatial and temporal microhabitat variations in opening multiple successional pathways in vegetation dynamics is illustrated and proves highly relevant for ecosystems with unpredictable or short-lived (20 years) patchy vegetation structures and microhabitats.