Lithologic controls on rock-derived nutrient cycling and soil organic carbon storage in perhumid temperate coastal rainforest
EMSL Project ID
51650
Abstract
Mineral weathering is an important supplier of plant essential nutrients and influences soil carbon sequestration yet the drivers and rates of mineral transformation and soil formation are still poorly understood, limiting our ability to develop predictive models of landscape evolution. The intensity and duration of the cold, wet climate in coastal temperate rainforests enhances soil carbon storage and the cycling of rock-derived nutrients in the terrestrial realm. The nutrients weathered from rock and soil interact with soil pore waters and are eventually transported to support aquatic productivity. Coastal temperate rainforests are geographically extensive, store significant soil carbon, and represent an intermediate ecosystem between cold arctic biomes and warmer and drier temperate forests, yet the soils remain understudied. We propose to examine the interplay of climate and lithology on rock-derived nutrient cycling and soil development in a perhumid temperate coastal rainforest (CTR) near Juneau, Alaska. Over 20 soil profiles were sampled by morphologic horizon (including organic and mineral soil horizons) to unweathered rock on midslope topographic positions across three distinct lithologies (igneous, metamorphic, and sedimentary). The proposed research will integrate soil mineralogical, geochemical, and micro- to nano-scale microscopy tools to quantify weathering rates and soil organic carbon storage. Quantitative x-ray diffraction (XRD), and inductively coupled mass spectrometry (ICP-MS) will detect elemental and mineralogical changes in different soil profiles. Mossbauer Spectroscopy (MS) will provide insights on the Fe minerals and the Fe-OM complexes concentrating in the subsurface mineral B horizons. Scanning electron microscopy (SEM) coupled with Transmission Electron Microscopy (TEM) will detect nano- to micrometer scale changes in rock and soil morphology that will be combined with quantitative elemental analysis to measure weathering rates by elemental composition changes. High-resolution imaging will also examine differences in mineral weathering features and organic coatings on the surfaces of minerals by rock type and landscape position. Confocal microscopy and XPS on a subset of samples will assess bacterial and fungal-mineral interaction on each rock type. This combination of tools will examine in detail the responses of rock-derived nutrient release and soil formation to intense inputs of energy and carbon in a perhumid temperate coastal rainforest, ultimately helping to address climate change by advancing the understanding of environmental systems across spatial scales. We expect results from this research will advance our knowledge and understanding of complex landscape patterns by resolving the structure of the base lithology and soils, which will facilitate building and improving ecosystem models. The work will establish a research framework and dataset for mineral weathering and landscape evolution in an understudied environment despite the importance of this region to carbon storage and ultimately climate change.
Project Details
Project type
Exploratory Research
Start Date
2020-12-01
End Date
2021-12-31
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members