What is driving the change in vegetation productivity in northern Eurasia? 

Monday, 15 December 2014
Pawlok Dass, University of Massachusetts Amherst, Geosciences, Amherst, MA, United States, Michael A Rawlins, University of Massachusetts Amherst, Amherst, MA, United States, Ben Smith, Lund University, Lund, Sweden, John S Kimball, The University of Montana, Flathead Lake Biological Station, Polson, MT, United States and Youngwook Kim, Univ Montana, NTSG, Missoula, MT, United States
High latitude terrestrial vegetation, by influencing and being influenced by the hydrological and carbon cycles, play a critical role in the global climate. Under a warming climate vegetation productivity is expected to increase. While agreement among remote sensing data point to an increase in vegetation greenness, there is considerable uncertainty about the magnitude and extent of this change. The uncertainty is still greater for northern Eurasia due largely to a sparsity of ground based observational data. IPCC projections suggest that northern Eurasia will become warmer and wetter. Improved characterization of terrestrial vegetation of northern Eurasia are dependent on the identification of the main drivers of change over the recent past.

In this study trends in vegetation productivity over northern Eurasia is analyzed using products derived from several remote sensing based algorithms as well as process-based models. A temporal and spatial analysis is conducted to determine the sensitivity of photosynthesis to abiotic variables like temperature, moisture availability and atmospheric CO2 concentration. We note reasonable agreement of an increasing trend of gross primary productivity but a disagreement about the rate of increase. Although gross primary productivity is highest in summer, the greatest percentage increase is seen in spring. Productivity increases are however not spatially homogeneous. Preliminary analysis of the abiotic variables also indicate a stronger relative change for the spring months compared to summer and autumn. This would suggest that abiotic factors are driving the phenological changes in vegetation.