Warming temperatures in the Northern Hemisphere have enhanced terrestrial productivity. Despite the warming trend, North America has experienced more frequent and more intense cold weather events during winters and springs. These events have been linked to anomalous Arctic warming since 1990, and may affect terrestrial processes. Here we analyse multiple observation […]
Large interannual variations in the measured growth rate of atmospheric carbon dioxide (CO2) originate primarily from fluctuations in carbon uptake by land ecosystems. It remains uncertain, however, to what extent temperature and water availability control the carbon balance of land ecosystems across spatial and temporal scales. Here we use empirical […]
Nitrogen isotopes in tree rings record the history of the nitrogen cycle—the critical nutrient that limits growth in many US forests. ECOSS faculty member Michelle Mack, along with colleagues from seven other institutions, recently published a paper that shows nitrogen availability in US forests declining over the past century, with […]
Permafrost, the “always-frozen” deep soil layers of the Arctic, naturally undergoes freeze-thaw cycles with the passage of the brief Arctic spring and summer, which thaws the uppermost layers and fosters a burst of tundra plant growth and pooling meltwater from thawed soil. For millennia, this cycle has re-frozen the […]
Native soil carbon (C) can be lost in response to fresh C inputs, via the “priming effect,” a phenomenon observed for decades yet still not understood. Using dual-stable isotope probing, Ecoss research showed that priming involves changes in the diversity and composition of two functional bacterial groups: a single-substrate pulse […]
Rapid Arctic warming is expected to increase global greenhouse gas concentrations as permafrost thaw exposes immense stores of frozen carbon (C) to microbial decomposition. Permafrost thaw also stimulates plant growth, which could offset C loss.Using data from seven years of experimental Air and Soil warming in moist acidic tundra, we […]
Human impacts on biogeochemical cycles are evident around the world, from changes to forest structure and function due to atmospheric deposition, to eutrophication of surface waters from agricultural effluent, and increasing concentrations of carbon dioxide (CO2) in the atmosphere. The National Ecological Observatory Network (NEON) will contribute to understanding human […]
Vessel length is an important but understudied dimension of variation in angiosperm vascular anatomy. Among other traits, vessel length mediates an important tradeoff between hydraulic efficiency and safety that could influence how plants respond to extreme weather with climate change. However, the functional significance of vessel length variation within individual […]
Sub-arctic birch forests (Betula pubescens Ehrh. ssp. czerepanovii) periodically suffer large-scale defoliation events caused by the caterpillars of the geometrid moths Epirrita autumnata and Operophtera brumata. Despite their obvious influence on ecosystem primary productivity, little is known about how the associated reduction in belowground C allocation affects soil processes. We […]
The land surface provides a boundary condition to atmospheric forward and flux inversion models. These models require prior estimates of CO2 fluxes at relatively high temporal resolutions (e.g., 3-hourly) because of the high frequency of atmospheric mixing and wind heterogeneity. However, land surface model CO2 fluxes are often provided at […]