Does permafrost disruption and landscape disturbance alter the carbon budget of High Arctic ecosystems?

by: Neal Scott, Canada Research Chair, professor Geography Dept. Queen's University

Abstract

High-Arctic ecosystems may serve as the “canary in the coal mine” by providing insights into the response of terrestrial ecosystems to future climate. As temperatures increase, however, permafrost melting also increases, and given the right combination of soil moisture content and depth of active layer this can lead to disturbances called active layer detachments.  At the Cape Bounty Arctic Watershed Observatory on Melville Island, Nunavut, we are exploring the hydrological and biogeochemical response of high-Arctic ecosystems to future climate regimes and landscape-scale active-layer detachments.  In undisturbed watersheds, terrestrial ecosystems on Melville Island are storing a small amount of carbon each year (roughly 7 g CmK ^-2 y^-1) while rivers are exporting about 1 g C m^-2 y^-1 as dissolved organic and inorganic carbon.  Particulate organic carbon losses in undisturbed watersheds are very small (~.001 g Cm^-2 y^-1).  Following disturbance, export of dissolved carbon in streams increased two-fold, while export of particulate carbon increased 10-fold to about 0.07 g Cm^-2 y^-1).  Changes in soil properties following disturbance, such as changes in bulk density and porosity, may further alter the exchange of other greenhouse gases such as methane.  Whether watersheds become net sources of carbon following disturbance will depend on changes in net carbon uptake by vegetation in disturbed areas.

Bio

Neal did his undergraduate work at Williams College (USA), then completed his MSc. in Soil Science/Ecology (1991) and his Ph.D in Forest Ecology at Colorado State University (1996).  Neal then worked at Landcare Research (Palmerston North, NZ) for six years and the Woods Hole Research Center (USA) for five years before coming to Queen’s in 2005. He is an assistant professor in Geography, and holds a Canada Research Chair (II) in Greenhouse Gas Dynamics and Ecosystem Management.  His research explores how plant/soil interactions influence carbon and nitrogen cycles at different scales, with an emphasis on how human activities (e.g. land-use change) have altered net ecosystem greenhouse gas emissions. In New Zealand, he helped develop national monitoring systems to quantify the contribution of soil and native ecosystems to New Zealand’s national carbon balance.  His current research explores how forest management could be used to enhance carbon sequestration in forests, the key factors controlling the greenhouse gas balance of high-Arctic ecosystems, and how conversion of land to grow biomass energy crops alters the net greenhouse gas balance of the ecosystem.