Greenhouse gas emissions from riparian zones are related to vegetation type and environmental factors.

Abstract

Riparian zones provide multiple benefits, including streambank stabilization and nutrient abatement. However, there is a knowledge gap on how the type of vegetation and environmental factors (e.g., soil temperature, moisture) within the riparian zone influence CO2 and CH4 emissions. Our objective was to quantify and compare CO2 and CH4 emissions from a herbaceous (grass) riparian zone (GRS), a rehabilitated riparian zone composed of deciduous trees, an undisturbed natural forested riparian zone with deciduous trees (UNF-D) or coniferous trees (UNF-C), and an agricultural field. Cumulative soil CO2 emission ranged from 23 to 105g CO2 -C m-2 . Carbon dioxide emissions were greatest (p<.05) in the GRS zone and lowest (p<.05) in the UNF-C riparian zone. The best predictors for CO2 emissions were soil temperature and soil organic carbon (SOC) content. Cumulative CH4 emission ranged from -23 to 253g CH4 -C m-2 . Methane emissions were greatest (p<.05) in the UNF-D and lowest (p<.05) in the GRS riparian zone. The best predictors for CH4 emissions were soil moisture, SOC, and photosynthetic photon flux density. The total CO2 -C equivalent (i.e., CH4 + CO2 ) was greatest (p<.05) for the GRS and lowest (p<.05) for the UNF-C riparian zone. The environmental factors controlling CO2 and CH4 emissions within the various riparian zones did not change; instead, changes were due to how vegetation within riparian zones influenced these controls.