Climate change and plant growth

B. Geerts

4/'99

Plant phenologists study the seasonal timing of life cycle events of plants. Observations between 1960-95 in the International Phenological Gardens (IPG), a Europe wide network with genetically identical clones of trees and shrubs, have shown a clear trend. Spring phenophases, such as flowering and leaf unfolding, have advanced by an average of 6 days, whereas autumn phases have been delayed by 5 days yielding an average lengthening of the annual growing season of 11 days as compared to the early 1960's (1). Satellite-based determinations of vegetation indices indicate a stretching of the growing season by about 7 days over the northern hemisphere land areas between 1970-1997 (2).

It is well-known that the increase in atmospheric CO2 enhances global biomass formation, for several reasons. The longer annual growth period in cold climates probably also contributes to this enhanced plant growth. However the enhanced biospheric activity, apparent for example in the accelerated tree growth in wide areas of Europe, is not only due to increased atmospheric CO2 concentration. In Europe the main cause may be inadvertent fertilization by nitrogen compounds in the soil water (1).

 

References

  1. Roetzer, T 1999. A study in phenology of Mid-Europe - analysis and trends. Preprint Volume, 16th International Botanical Congress, St. Louis MS, August 1999.
  2. Schwartz, M. D. 1999. Integrating satellite and surface phenological measures. Preprint Volume, 16th International Botanical Congress, St. Louis MS, August 1999.