Search Results for: ye r
Patterns of bryophyte succession in a 160 year chronosequence in deciduous and coniferous forests of boreal Alaska
Bryophytes are dominant components of boreal forest understories and play a large role in regulating soil microclimate and nutrient cycling. Therefore, shifts in bryophyte communities have the potential to affect boreal forests’ ecosystem processes. We investigated how bryophyte communities varied in 83 forest stands in interior Alaska that ranged in […]
Ecosystem vs. community recovery 25 years after grass invasions and fire in a subtropical woodland
Despite a large body of research documenting invasive plant impacts, few studies have followed individual invaded sites over decades to observe how they change, and none have contrasted how compositional impacts from invasion compare to ecosystem-process impacts over a multi-decadal time-scale. Using direct measurements of plant density and composition and […]
Compensatory water effects link yearly global land CO2 sink changes to temperature
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 […]
Deep Yedoma permafrost: A synthesis of depositional characteristics and carbon vulnerability
Permafrost is a distinct feature of the terrestrial Arctic and is vulnerable to climate warming. Permafrost degrades in different ways, including deepening of a seasonally unfrozen surface and localized but rapid development of deep thaw features. Pleistocene ice-rich permafrost with syngenetic ice-wedges, termed Yedoma deposits, are widespread in Siberia, Alaska, […]
Tundra is a consistent source of CO2 at a site with progressive permafrost thaw during six years of chamber and eddy covariance measurements
Current and future warming of high latitude ecosystems will play an important role in climate change through feedbacks to the global carbon cycle. This study compares six years of CO2 flux measurements in moist acidic tundra using autochambers and eddy covariance (Tower) approaches. We found that the tundra was an […]
Non-linear CO2 flux response to seven years of experimentally induced permafrost thaw
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 […]
Non-linear CO2 flux response to seven years of experimentally induced permafrost thaw
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 […]
A Bayesian model for xylem vessel length accommodates subsampling and reveals skewed distributions in species that dominate seasonal habitats.
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 […]
Isotope partitioning of soil respiration: A Bayesian solution to accommodate multiple sources of variability
Isotopic methods offer great potential for partitioning trace gas fluxes such as soil respiration into their different source contributions. Traditional partitioning methods face challenges due to variability introduced by different measurement methods, fractionation effects, and end-member uncertainty. To address these challenges, we describe a hierarchical Bayesian (HB) approach for isotopic […]