Rationale

Justification for indicator selection

Increasing air temperatures are significantly affecting the duration of the growing season over large areas of Europe (Scheifinger et al., 2003). The number of consecutive days with temperatures above 0 ^oC can be assumed to be the period favourable for growth. The timing and length of this frost-free period is of interest to naturalists, farmers and gardeners among others. The impact on plants and animals is reported mainly as a clear trend towards an earlier start of growth in spring and its prolongation into autumn (Menzel and Fabian, 1999). A longer growing season allows the proliferation of species that have optimal conditions for development and an increase in their productivity (e.g. crop yields, insect population), and the introduction of new species (very sensitive to frost) in areas previously limited by unfavourable thermal conditions. Changes in management practices, e.g. changes in the species grown, different varieties, or adaptations of the crop calendar, can counteract the negative effects of a changing growing season (pests) and capture the benefits (agricultural crops).

Scientific references

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