Climate change alters the life cycle of plants

Have you ever found wild asparagus completely out of season, for example in October, because a sudden heatwave altered the plants' cycle? Or noticed bees unusually active during the winter months, because temperatures did not follow the usual pattern of midwinter? These are just small examples of a phenomenon that is very large and, above all, serious, due to climate change, which alters the life cycle of animals, trees, and plants, threatening biodiversity, the crops we eat, and, in general, the survival of numerous species. But what exactly is happening?



The effects of climate change on ecosystems

When talking about climate change, we often forget that it is not just about generally higher temperatures throughout the year, but about anomalous extreme peaks, and an alteration in the succession of periods of heat and cold. Heat peaks during autumn or winter, for example, can disrupt the biological clock of plants, “tricking” them into thinking spring has arrived and stimulating them to wake up, thus disrupting their metabolism. There are numerous effects of climate change on the life cycle of ecosystems, and they involve all layers of the biosphere.

First of all, plants and trees see their daily and annual rhythms thrown out of balance. Many insects wake up earlier than expected and do not find the nutrients they need to survive that they expect to find in spring. The migratory routes of some birds also change, because they no longer find the conditions to live in their usual places, thus altering the entire functioning of the ecosystems their routes touch – or no longer touch – and also changing the food chain of other species.

The circadian rhythm of trees

As for trees and plants, the main reason their normal life cycle is altered is the disruption of the circadian rhythm. This term refers to the sequence of physiological changes that every organism experiences throughout the day, which is linked to the rising and setting of the sun.

All living beings, including humans, have a circadian rhythm, which can be altered even by very small changes. For example, when we switch from standard time to daylight saving time, our circadian rhythm is affected, because the alternation of day and night, and the way we experience the hours of sunlight and darkness, has been modified. The first hours of light are generally the times when we are most active, and the peak is reached during the afternoon, while with the arrival of darkness energy decreases: yet, when there are too many hours of light, the overall well-being of our body suffers, because it does not find the rest it gets with darkness, which arrives late.

The circadian rhythm is managed at the genetic level and is different for each species: for plants and trees, it does not depend only on the hours of light, but also on temperatures. If temperatures increase, in fact, especially if they do so in an anomalous and sudden way, not following the regular alternation of the seasons, the circadian rhythm of plants is affected, as is their annual life cycle marked by the seasons.

Therefore, it happens that some plants suddenly bloom, much earlier than they should, tricked by milder temperatures during the winter. Fruit trees finish their cycle early, then causing problems for the harvests. Furthermore, if plants bloom early, and then a new sudden winter frost arrives, the blossomed buds perish due to the cold.

Confirming the negative consequences of these absolutely anomalous dynamics is a study that started in 2018 and observed and collected data on the plant inhabitants of a forest in Umbria for over 800 days. The project Tree monitoring to support climate Adaptation and mitigation through PEFC Certification collected a lot of data on the amount of water absorbed by the plants, the quantity and variety of foliage, and the possible presence of diseases. The results of the research confirmed the early budding and a delay in autumn senescence, events that negatively affect the life cycle of flowers, therefore the production and maturation of the fruits of many plants. In the forest of Piegaro and, presumably, in all other forests, trees do not experience a sufficiently long period of cold, also experiencing difficulties waking up from winter dormancy, which only happens partially: their productivity is affected, but also their resistance to diseases, and plants therefore become more fragile.

All this data inevitably concerns the consequences of climate change on the plant world: trees and plants, and consequently all other living organisms, experience a constant alteration of their life rhythms, modifying the functioning of entire ecosystems, damaged by changes in temperature. The consequences of global warming are beginning to create increasingly serious problems for the survival of all the species that inhabit our Planet, disrupting the functioning of entire ecosystems. How much more damage will it be necessary to cause to the biosphere before implementing more incisive practices against climate change?