2026 Theses Doctoral

Forest Responses to Novel Disturbance in a Tropical Peatland

Eberhard, Erich K.

Human activities are driving significant reorganization of our planet’s biosphere, with profound consequences for biodiversity, ecosystem functioning, and our own wellbeing. Climate change and land-use change, in particular, are catalyzing deviations in patterns of disturbance away from historic baselines, fueling ecological responses that are difficult to predict. Across tropical landscapes, novel fire regimes are reshaping forest structure, biodiversity, and composition in ways that can push systems across resilience thresholds and into states of sustained degradation. Against this backdrop, critical gaps remain in our understanding of where, when, how, and why distinct attributes of disturbance regimes are likely to drive ecological responses, and how these relationships are modulated by the co-occurrence of other disturbances, limiting out ability to implement effective management in a rapidly changing world. In this dissertation, I address these gaps by approaching disturbance regimes as dynamic and cumulative, assessing the potential for targeted interventions to disrupt synergistic disturbance interactions, and integrating cutting-edge methodologies to elucidate lasting impacts on remnant forests in fire-fragmented landscapes.

In Chapter 1 and Chapter 2, I leverage over a decade of vegetation monitoring data from a heterogeneously fire-degraded tropical peatland to disentangle the role of distinct fire regime characteristics in shaping post-fire stands and examine the potential for canal-blocking to support forest recovery across a gradient of burn histories. The results indicate that exposure to fire is associated with massive declines in biomass and biodiversity, with repeated fires pushing forests further along directional degradation pathways toward states characterized by open, dry, and highly flammable assemblages. This pattern is consistent with positive feedback loops documented across other fire-naive tropical landscapes, which trap systems in cycles of burning that prevent the recovery of mature forest. However, I find evidence that hydrological restoration may help disrupt this feedback in tropical peatlands by creating conditions favorable for forest regeneration, even in heavily degraded landscapes lacking remnant canopy. More broadly, this finding supports the utility of management interventions that seek to reshape the feedbacks underlying degradation, especially in systems prone to multiple interacting disturbance types.

In Chapter 3, I investigate how forest architecture influences soundscapes across an edge-interior gradient in the same fire-fragmented landscape. My findings demonstrate the sensitivity of distinct soundscape components to different architectural attributes, which are in turn structured by proximity to forest edge, suggesting that any edge effects on soundscapes are likely to be partially mediated through changes in forest architecture. In addition, this chapter highlights the promise of integrated data streams from emerging technologies to enable fine-resolution and passive ecological monitoring of previously undetectable responses to disturbance.

Collectively, this research underscores that the behavior of tropical forest systems cannot
be fully understood without careful consideration of disturbance regimes, interactions, and
legacies, especially in our era of rapid environmental change. Looking ahead, this research points to the importance of complex systems-informed restoration frameworks for rehabilitating forests in the decades to come, as well as to a new frontier for forest monitoring that can empower data-driven management amidst an unfolding crisis.