Ecosystem responses to recent climate change and fire disturbance at northern high latitudes: observations and model results contrasting northern Eurasia and North America

Abstract

Vegetation composition at high latitudes plays a critical role in the climate and, in turn, is strongly affected by the climate. The increased frequency of fires expected as a result of climate warming at high latitudes will feedback positively to further warming by releasing carbon to the atmosphere, but will also feedback negatively by increasing the surface albedo. The net effect is complex because the severity of fire affects the trajectory of both carbon stocks and albedo change following a fire, and these are likely to differ between high latitude ecosystems in North America and northern Eurasia. Here we use growth trajectories, productivity trends and regional carbon fluxes to characterize these fire-and climate-driven changes.

Attribution of divergent northern vegetation growth responses to lengthening non-frozen seasons using satellite optical-NIR and microwave remote sensing

“…A given daily increase in the NF season also produces a larger NDVI JJA increase in tundra (0.25 ± 0.2%) and boreal biomes (0.13 ± 0.2%), and relatively weak growth response in grassland (0.05 ± 0.1%) and temperate forest areas (0.06 ± 0.2%). Our FT and CO 2 correlation results confirm previous reports documenting a strong link between the timing of the primary spring thaw event defined from satellite microwave remote sensing and the onset of the vegetation growing season in northern biomes (Goetz et al 2007;Kimball et al 2004;McDonald et al 2004). Our findings also support previous findings that a lengthening NF season coupled with increasing disturbance is likely to promote respiration and carbon emissions over productivity, diminishing HNL carbon sink strength (Angert et al 2005;Yi et al 2013).…”

An estimate of the terrestrial carbon budget of Russia using inventory-based, eddy covariance and inversion methods

“…Piao et al (2011) have observed a decline of spring and summer NDVI since 1997 after two decades of greening, and attributed this to climate trends. Over 1982, Goetz et al (2007 analyzed AVHRR vegetation indices and found increases in Northeast Siberia and decreases in the Yakutsk region, attributed to recent fire emissions. Severe impacts appear now to have become a typical feature of the current fire regime.…”

An Automated Approach to Map the History of Forest Disturbance from Insect Mortality and Harvest with Landsat Time-Series Data

“…NDVI is related to the structural properties of plants, including Leaf Area Index (LAI), Absorbed Photosynthetically Active Radiation (APAR) and leaf biomass [10]. Widespread AVHRR NDVI declines have been reported further north in the Canadian boreal forest and have been associated with disturbances from fire, insect outbreak and changes in climate [11][12][13][14][15][16]. However, these boreal forests have limited human access and have not had a decline in NDVI throughout the 1982 to 2007 AVHRR record of measurements.…”