Scales and drivers of variability in dissolved organic carbon across diverse urban watersheds
May 2021 - April 2024
- National Science Foundation
A critical gap for ecosystems science is that human activities alter the spatial and temporal scales of existing ecological processes and introduce novel sources of ecological variability. Most ecosystems worldwide are impacted by human activities; yet the effects of human activities across scales are not adequately represented by existing ecosystem models. This is especially true for models of aquatic carbon (C) cycling and fluxes. Only recently has the magnitude of fluvial C fluxes been recognized within the global carbon cycle; yet these estimates explicitly ignore the influence of human activities, such as urbanization. We propose to assess urbanization effects on dissolved organic carbon (DOC)—the largest flux of carbon in streams—focusing on how urbanization affects ecosystems in regionally-specific ways. We hypothesize that human activities introduce novel sources of ecological variability and affect the spatial and temporal scales of ecological processes differently in different geographies and urban contexts. We will test this hypothesis using a comparative approach to understand urban effects on DOC. We will collect data on DOC quality and dynamics at 600 sites across five urban study areas to develop a multi-scale understanding of the quantity and quality of DOC in urban systems. We will use spatial statistics and time-series analyses to identify key spatio-temporal characteristics of human development (e.g., wastewater infrastructure, housing density) and biophysical factors (e.g., discharge, precipitation, canopy cover) that control the concentration, characteristics, and bioavailability of DOC. Our research takes a novel approach to jointly consider how the human and ecological dimensions of ecosystem ecology interact to control the quality, quantity, and timing of DOC entering watersheds across the continent.