Vegetation Structure and Species Diversity in Secondary Forests as Indicators of Ecosystem Stability

Abstract

Secondary forests constitute one of the most ecologically dynamic and globally significant forest categories, covering hundreds of millions of hectares across the tropics and subtropics. This systematic review evaluates the relationship between vegetation structure, species diversity, and ecosystem stability in secondary forests, synthesizing evidence from fourteen peer-reviewed studies—seven from Indonesian and adjacent Southeast Asian contexts and seven additional foundational studies from the international ecological literature. Evidence across these sources consistently demonstrates a positive correlation between structurally complete, multi-strata vegetation communities and indicators of ecological stability including active regeneration, functional resilience, and resistance to disturbance. The Shannon-Wiener diversity index (H') reported across studies typically ranges from 1.4 to 2.5, classified as moderate, and is positively associated with productivity, nutrient cycling, and community persistence. However, this general pattern is frequently complicated by the dominance of invasive species—including Chromolaena odorata, Imperata cylindrica, and Piper aduncum—which suppress understory regeneration and reduce long-term diversity even where aggregate H' values appear acceptable. Drawing on the successional ecology and biodiversity literature, this review argues that vegetation structure and diversity metrics are necessary but not sufficient indicators of stability; their interpretation must be contextualized within disturbance history, invasion pressure, and anthropogenic land-use trajectories. Practical implications for secondary forest management and monitoring are discussed.