Phenological campaign, autumn 2023.

Our school is located in the furthest north region of Croatia, Međimurje, in a town called Prelog (46° 20′ 13″ N, 16° 36′ 54″ E). Our town is located on the river Drava which gives students the ability to learn biology and geography from real world examples.

For our campaign we chose three trees, two birch trees, one in front of our school and one behind in our school yard and a fig tree that is behind right next to the school. We collected data two times a week and photographed the marked leaves on each tree.

Activity 1. Introduction, location, species determination, marking leaves

Activity 2. Color change - tracking, GrowApp

Activity 3. Graphs and visualization

Conclusion

The birch in front of the school was the only one that we observed that lost its leaves, and that was after a big storm. We think that the leaves would have remained on the other two observed trees, but there is less protection with the objects, so maybe that was the reason.

Our hypothesis was that the fig leaves would fall off first because it is a Mediterranean plant that is not indigenous to our continental regions. However, we had to reject our hypothesis. The fig tree is in the lee on the south side, which is the main reason that it was protected from bad weather. It still has fruit today, as can be seen in the attached photo.

Birch trees barely changed the color of their leaves throughout the observed period. We believe that the reason is extremely warm weather and average daily temperatures of around 17 C, which is extreme for this time of year.

Comparing with the available data of schools in similar geographical latitudes, many fig trees lost their leaves earlier, even about two or three weeks earlier, while the situation with birch trees is similar to ours.