Details

Autor(en) / Beteiligte

• Chadwick, K Dana

Titel

Geomorphically Driven Biogeochemical Gradients and Their Influence on Tropical Forest Canopies

Ort / Verlag

ProQuest Dissertations & Theses

Erscheinungsjahr

2016

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• The Peruvian Amazon is home to over half a million square kilometers of tropical forest, more than three quarters of which exists on terrace landforms. The characteristics of terrace ecosystems have been contrasted with neighboring floodplains and compared with terraces of different ages, but the ecological and biogeochemical complexity that exists within these landscapes has not been studied in detail. These landforms are often considered to be relatively homogeneous, despite the fact that they are subject to dynamic processes driven by ongoing landscape evolution. In this dissertation, I consider the role of geomorphic gradients and biogeochemical processes in determining soil and foliar nutrient distributions across a terrace formation in Los Amigos Conservation Concession (LACC) in the southern Peruvian Amazon. I seek to determine whether the evolution of terrace landscapes has a material effect on soil properties along hillslopes and whether the interplay of topographic position and differing resource availability determines the spatial patterns of foliar nutrient concentrations of canopy trees. Chapter 2 focuses on uncovering patterns in soil concentrations of rock-derived nutrients across hillslopes with differing morphologies, as well as identifying the processes that drive these patterns. I found that hillslope erosion, driven by stream incision, is causing nutrient rejuvenation within this landscape, and that calcium in particular is tightly retained through biotic cycling by the ecosystem. Chapter 3 demonstrates that airborne high fidelity imaging spectroscopy data can be used to predict canopy foliar nutrient concentrations, as well as leaf mass per area, at the scale of emergent canopies across floodplain and terrace landforms within LACC. In Chapter 4, I utilize the understanding of soil nutrient distributions gained in Chapter 2, and the high resolution maps of canopy foliar nutrient concentrations developed in Chapter 3, to consider the role of geomorphic processes in controlling the spatial distributions of canopy foliar nutrient concentrations. Through these studies, I determine that hillslope and biotic processes drive biogeochemical gradients that are reflected in both soil nutrient availability and foliar nutrient concentrations within a terrace landform in the lowland Peruvian Amazon. These findings suggest that fine scale geomorphic processes play a significant role in determining spatial distributions of biogeochemical and ecosystem processes across tropical lowland terrace landscapes.