The study showed that seasonal rhythms of nature can vary significantly even over short distances, sometimes creating the impression that neighboring areas are thousands of kilometers apart.
By creating a map of seasonal vegetation cycles based on twenty years of data, an international team of scientists was able to track in detail how the reflection of infrared light by plants changes throughout the seasons. This allowed them to establish precise growth and dormancy periods for plants that grow in various corners of the Earth.
The traditional scheme of changing seasons — winter, spring, summer, autumn — accurately describes plant life in temperate latitudes such as Europe and North America. However, in tropical and arid regions, the situation is different. Here, temperature ceases to be the main determining factor for plant growth, and the availability of water and light comes to the forefront.
“Seasonality is often viewed as a simple process, but our work shows that the natural calendar is much more complex,” comments one of the study's authors, ecologist Drew Terasaki Hart from the Australian government research organization CSIRO. He notes that particularly pronounced changes in local seasonal cycles are observed over short distances.
The scientists found significant differences in seasonal cycles on mountain slopes in the tropics and in Mediterranean climate zones. An example is coffee plantations in Colombia: farm plots separated by just one day's journey through the mountains can have completely different harvest ripening times, as if they are located in opposite hemispheres.
These results help explain the high level of biodiversity in the tropics. When neighboring ecosystems operate on different seasonal schedules, it leads to plants and animals reproducing at different times. Over time, this can cause divergences in populations and contribute to the formation of new species.
The findings of the study are important not only for understanding the evolution of terrestrial ecosystems. The authors of the research are confident that this approach can be adapted for studying river and ocean ecosystems and for tracking nature's adaptation to climate change. Moreover, the new perspective on seasonality may prove useful in agriculture and even in epidemiology, as many infectious diseases are also subject to seasonal changes.
