Carbon pools and ecosystem properties along a latitudinal gradient in northern Scots pine ( Pinus sylvestris) forests

Abstract

A significant portion of the Earth’s carbon is in forested terrestrial ecosystems. Carbon fluxes to and from these ecosystems in response to climate change have the potential to alter global climate. To understand how forest carbon budgets may be affected by climate, we observed patterns of carbon storage, forest structure, and composition in Scots pine forest ecosystems at nine sites along a northern latitudinal gradient (50–70°N) crossing Poland, Lithuania, Latvia, Estonia, and Finland. This gradient is characterized by a northward decline in average annual temperature (Δ = ca. 9°C) and precipitation (Δ = ca. 300 mm). Total ecosystem carbon, decomposition rates, and litterfall amounts all decreased nonlinearly with increasing latitude. Plant species richness in the ground flora also decreased with increasing latitude. However, the percent cover of lower canopy vegetation varied asystematically with respect to latitude, temperature, or precipitation. Our results are largely consistent with models and analyses indicating that northern latitude forests may respond to predicted climate changes with increased carbon sequestration. In the short term, however, these forests may be a source rather than a sink for atmospheric carbon as the relative distribution of C among ecosystem components adjusts in response to changing climatic conditions.