Trees, those giant witnesses of the passage of time, have a complex and varied life cycle. Depending on factors such as climate, pests, or even human actions, trees can live for centuries or die much earlier than expected. But, What are the causes that lead to their death? It is not always easy to identify the factors that cause the decline of these long-lived but also fragile living beings.
Throughout this article, we will unravel the main reasons that explain why trees die. From environmental factors such as droughts and heat waves, to the influence of pests and fungi, every detail explains how these majestic organisms can undergo drastic transformations and even disappear from our landscapes. Moreover, human action plays a major role in this equation, aggravating many of the natural threats that trees face.
Genetic factors and the programmed life of trees
Image - Wikimedia / Snufkinit
Like any other living being, trees have a kind of “genetic program” that determines how long they will live. The longevity of trees is regulated by their genes and their ability to withstand external factors. Some species, such as redwoods, can live for thousands of years, while others, such as sunflowers, barely survive a few months. This difference in life cycle is closely related to the ability of trees to adapt to the conditions of their environment.
However, although trees have a long life span, they are not immortal. They reach a phase of 'senescence', that is, aging, in which their tissues and cells begin to deteriorate inevitably, facilitating the fall of branches or, in extreme cases, the complete collapse of the tree. It is in this phase that the tree is most vulnerable to external factors, such as climate or pests, which can accelerate its death.
The impact of extreme weather conditions
Extreme weather conditions are one of the main causes of tree deathIncreasingly, with climate change, we are seeing an increase in phenomena such as prolonged droughts, heat waves, gales and floods that significantly weaken trees.
A key phenomenon affecting trees during droughts is embolism: when a lack of water blocks the channels that transport nutrients from the roots to the leaves. This causes the tree to collapse internally. Areas with a Mediterranean climate, where droughts are more common, are especially vulnerable to this phenomenon. In addition, Global warming is driving tree species to higher ground, as conditions in low-lying and southern areas are becoming too arid for traditional species to survive.
Plagues and diseases
Pests and diseases are another major threat to tree survival.Pathogens such as fungi and bacteria, as well as devastating insects, weaken trees and prepare them for certain death. A clear example of this is the spread of fungi such as Phytophthora, which affects the roots of the tree and prevents them from absorbing water and nutrients properly. In addition, there are pests such as bark beetles, which bore into the bark of pine trees, and the hairy cork caterpillar, responsible for massive defoliation in holm oaks.
Furthermore, microorganisms and pests not only affect individual trees, but can have a devastating effect at the forest community level. In years of high humidity, fungi spread more quickly, and pests, if they find favorable conditions, can generate population explosions that end in the death of large areas of forest.
Devastating fires
In many regions of the world, especially those with a Mediterranean climate, forest fires are a common event. Historically, several ecosystems have evolved to adapt to these natural disturbances, with species developing resilience mechanisms. For example, some trees have thick barks that protect them from fire, while others, such as the Aleppo pine, have an incredible ability to regenerate. However, not all trees are equally prepared.
Species such as the black pine (Pinus nigra) and the Scots pine ((Pinus sylvestris)) are particularly vulnerable to large-scale fires. Moreover, fires are not only more common today, but also more intense and extensive due to climate change. The increasing frequency of fires leads to the destruction of large swathes of forests that fail to recover, altering the landscape irreversibly.
Human action: a key factor
Human activity is perhaps one of the most determining factors when it comes to the death of trees. Indiscriminate felling, uncontrolled urbanization and poor management of urban green areas These are just some of the reasons why many trees die prematurely.
In the cities, improper pruning leads to weakening of trees. Extreme pruning, often carried out without proper knowledge, opens large wounds through which fungi and insects can enter, and if disinfected equipment is not used, the problem worsens by spreading diseases between trees.
What can we do to protect trees?
It is crucial that both citizens and public managers become aware of the dangers that threaten trees in their area. Protecting trees requires better management of green areas and avoiding harmful practices, such as extreme or out-of-season pruning. Trees not only add beauty to our surroundings, but are key to mitigating climate change by absorbing carbon dioxide. It is our duty to protect them.
As for forestation, Forest management plans must take into account new climatic realitiesPlanting resilient species and diversifying ecosystems can help make forests more resilient to pests, fires, and extreme weather events.
Finally, initiatives such as AlertaForestal allow citizens to collaborate in the early detection of forest problems in Catalonia. Being aware of the health of trees and reporting their problems is something we can all do to contribute to the well-being of our planet.
Tree death, although it may seem like an inevitable natural cycle, is something we can mitigate if we act responsibly. From forest management to simply caring for urban trees, every small action counts to keep forests alive in the long term.