UCLA

This dissertation investigates the role of peatlands as critical carbon (C) reservoirs that sequester approximately 600 gigatons of C globally, effectively acting as a significant buffer against climate change. Despite their limited geographic extent—covering only 3% of the Earth's surface—peatlands store nearly twice the C of all global forests combined. This exceptional C storage potential is largely due to the waterlogged, anoxic conditions in these ecosystems that inhibit microbial decomposition and allow organic matter to accumulate over millennia. However, peatlands are highly vulnerable to both natural and anthropogenic pressures, including climate change, land-use modifications, and direct human disturbances, all of which threaten their capacity to serve as long-term C sinks. This dissertation leverages isotopic analysis to examine peatland C dynamics across diverse regions and contexts by exploring the mechanisms driving C dynamics in tropical, boreal, and temperate peatlands, focusing on both surface-derived and deep peat C emissions and accumulation. Tropical peatlands, which differ from boreal and temperate peatlands due to consistently warm temperatures and seasonal rainfall, contain highly dense C deposits but are also at heightened risk of C release under changing rainfall patterns. One case study examines tropical peatlands in Central America, where consistently warm temperatures and seasonal rainfall create dense C deposits. These tropical systems are especially susceptible to C loss with changing rainfall patterns, potentially releasing stored C from deep peat layers. In boreal regions, experimental warming simulates future climate conditions, assessing how elevated temperatures and CO₂ concentrations affect C storage across peat depths. Additionally, this dissertation uses global radiocarbon data to analyze peat accumulation and stability across climates, providing insights into regional differences in peatland resilience under environmental changes. These studies together highlight the significant impact of environmental variables such as precipitation, temperature, and proximity to coastlines on peatland C dynamics, as well as the potential influence of human activities like agriculture drainage and peat extraction on C loss. Findings underscore the importance of conserving and protecting pristine peatlands, which, as natural C sinks, are vital for mitigating greenhouse gas emissions. Overall, this dissertation underscores the critical importance of peatlands in global C cycling and climate regulation. The research highlights the necessity of conservation efforts to protect these ecosystems from degradation, as their disruption could lead to substantial greenhouse gas emissions and further accelerate climate change. By examining the complex interactions between environmental conditions, C sequestration, and human impacts, this dissertation contributes to a deeper understanding of peatlands' vulnerability and resilience, informing strategies for their preservation in a rapidly changing world.