Phenology is responsible for the study of the changes associated with the seasons experienced by living beings, depending on their idiosyncrasy and especially the climate cycle. Phenological observations are particularly interesting in flowering plants, which can act as indicators of annual meteorological behavior or even as witnesses to climate change.
Each of the stages in the life cycle of plants—flowering, foliation, flowering, leaf color change, and leaf fall—is a result of the activity of plant hormones. These substances are induced in some cases by the plant’s biological clock and, in many others, by the incidence of environmental factors, such as the quantity and quality of light (photoperiod), the relative humidity of the atmosphere and of land, and maximum and minimum temperatures, especially the extreme.
Global warming in recent decades has changed the meteorological conditions considered normal, introducing great uncertainty during the different phases of the life cycle of plants and causing delays, development, or unpredictable behavior.
Flowers, very perfect sensors
Flowers are organs with a complex architecture whose formation requires a high input of substances and energy. The flowering period thus becomes a period of extraordinary sensitivity to environmental changes.
Current global warming is increasing the length of summer in Mediterranean climates. The progress of the previous spring season is more evident, with greater humidity, more moderate temperatures, and favorable conditions for flowering.
As a result, it is known that some species open their flowers earlier. This change has various consequences for biodiversity, ecosystems, and the services they provide.
This anticipation of months that are often prone to climatic extremes, such as frost or hail, puts the continuation of fruit and seed formation at risk.
Likewise, the lack of synchronization between flower production and the hatching of insects, key to pollination, reduces seed production by a significant percentage, which means a reduction in the new generation of offspring. The reduction of populations, especially of threatened species, leads to the risk of extinction for many of them.
The nutrient source of fruits and seeds is the basis of the food framework that sustains the ecosystem. The reduced flow of matter and energy makes them more vulnerable to impacts, such as the loss of biodiversity or the inclusion of invasive exotic species.
Less productive fruit trees
The socioeconomic consequences of this improvement in supply services are significant, such as the quality, quantity, and cost of agricultural production.
Although it has been observed that some species, in the face of an unpredictable climate, can adapt to changes and, despite the development of flowering, maintain their productive success, the current data on agricultural production does not.
Fruit trees of the Rosaceae family, such as almonds, cherry trees, plums, and pear trees, reduce their productivity or produce poor-quality fruits if flowering occurs early.
Allergies also come early
Air quality also changes with the early flowering of many plants. Pollen from olive trees, grasses, and plantain shades affects a large part of the population with allergies, which involves a lot of socioeconomic losses as well as a deterioration of health.
The development of flowering in most of these plants represents an extension of the pollen calendar and the incidence of these conditions.
The great grasslands of the Cape region of South Africa, with their incredible chromatic diversity, are a good example of how flowering can be a great tourist attraction.
Other examples of the cultural value of blossoming are the Hanami of cherry trees in Japan, which is linked to rich traditions, and the cherry trees of Jerte Valley. The unpredictable development of the flower can lead in these cases to large losses in local economies, which find its essential support.
The uncertainty of the future
Climate predictions for the rest of this century raise uncertainty about crop behavior. Rising extreme temperatures, heat waves, and hot nights during spring can cause serious changes in the flowering season.
As has happened throughout the history of biodiversity, some plant species can adapt their biological clock to the new annual distribution of seasons. In others, on the contrary, the reduction of their productivity will lead to a change in their distribution areas or even local losses.