The importance of hurricanes for the climate and wildlife

13/11/2020

More than two million hectares were affected this year by the drought in the north of the country. While in the south came the rains and also the hurricane season. The Civil Protection System sends informative bulletins to take precautions and inform in a timely manner about the influence of these meteors in the Gulf of Mexico, the Pacific, and the Mexican Caribbean.

We know a lot about the effects of hurricanes, since they leave floods, loss of crops, road obstructions, landslides, hundreds or thousands of victims, and economic losses in the millions. However, little is known about the importance of these types of natural phenomena for the climate and wildlife.

Hurricanes are like air conditioners for the earth's atmosphere, stabilizing the temperature from the equator to the poles (south and north) becoming natural climate regulators. The movement of masses of hot air form winds that lower the temperature in the tropics, if this does not happen, life would be very difficult in this region. In addition, hurricanes are an important source of freshwater for the continents, thanks to the rains that accompany them.

Simply put, hurricanes originate in open frames in the equatorial zone, they feed on heat and low atmospheric pressure, that is to say, very warm waters release vapor in areas where the air exerts very little pressure on the earth. The combination of these two elements generates movement of the hot air masses (much vapor) toward the atmosphere, then upward currents of wind are formed that turn counterclockwise, the rotating form makes it also called a cyclone.

In their initial form, they are called tropical depressions, and when the strength of the winds increases they become hurricanes of different categories. According to the Saffir-Simpson classification, they go from category 1 with winds of approximately 63 km/h, to category 5 which is the strongest, with winds up to 300 km/h. In this way, they reach the continent in the form of rain and storms. The arrival of these large amounts of rain and moisture, significantly influence the development of vegetation on the coasts and inland and carry water for rainfed crops and groundwater (ie groundwater).

Can hurricanes be good and bad at the same time? Despite their importance in climate regulation and water supply, hurricanes are considered negative phenomena from the human point of view and are classified as "natural disasters". In the history of hurricanes, the most terrible ones that remain in historical memory have been those that have impacted human populations and have left considerable human and economic losses, such as Hurricane Gilberto in 1988 (Quintana Roo, Mexico) and Catrina in 2005 (New Orleans, United States); while other hurricanes, even as intense, such as Hurricane Dean in 2007 (Quintana Roo) were not given the same importance in official records because they did not directly affect large cities or tourist areas.

The benefit and importance for our climate and for other living beings is rarely mentioned. Forests and jungles depend on environmental humidity and rainwater for the production of leaves, flowers, and fruits. Wild animals, mainly those that eat plants (herbivores), are seen in serious feeding problems if droughts are prolonged. Therefore, the harmful aspect of a hurricane will depend on the perspective we use; while we cannot underestimate the local impact and affectation, we must not lose sight of its benefits at other scales.

Hurricanes, climate change, and wildlife

Since hurricanes are an integral part of the climate in the tropics, they are part of the dynamics and natural history of ecosystems and species, but in recent decades their frequency and intensity have increased as a consequence of climate change (i.e. they are more numerous and of higher category), for which we do not know if the ecosystems, species or ourselves are prepared. If we add to these processes related to human activities such as deforestation in all types of vegetation and demographic expansion, we increase their negative effects and we become increasingly vulnerable to these natural phenomena.

How can a hurricane affect wildlife? This is a relatively recent concern and information is scarce. One current research task is to assess how wildlife species are affected. A hurricane damages vegetation and the habitat where wildlife lives, feeds, and reproduces. But how much damage is there? In a study conducted in the Quintana Roo jungle, the impact of a major hurricane on both the vegetation and the animals in the jungle (e.g. deer, large birds, large rodents, badgers, wild boar, armadillos, etc.) was evaluated. It was found that the greater the damage to the trees, the less abundant the fauna was. However, not all animals were damaged equally, some showed greater sensitivity to damage and others showed greater resistance.

For example, animals that feed on leaves, flowers, and fruits (herbivores), such as white-tailed deer, temazate, tepezcuintle, cherries, and pheasants were the most damaged and their abundance decreased by 40 to 90%, compared to their pre-hurricane abundance. On the other hand, omnivorous species, that is, species that feed on insects, worms, roots, including some parts of plants, such as wild boar, badger, and mountain turkey, showed little change in abundance (10 to 15% lower abundances after the hurricane).

The armadillo, which is the most omnivorous of all, showed an increase in abundance after the hurricane. This is because while food for herbivores is scarce, it can increase food for omnivores because of all the decomposing organic matter that fell to the ground (branches and leaf litter). Where populations of insects, worms, and worms, which are potential food for omnivores, can be increased.

It is important to note that both vegetation and animals have the ability to recover. Precisely, in a period of 3 to 12 months after the hurricane, 98% of the trees had leaves, new branches, and, although in low quantities, some trees began to produce flowers and fruits. The most affected fauna (e.g., cereque, tepezcuintle, deer, and temazate) did not achieve abundances similar to those recorded before the hurricane, but they did show recovery with respect to the abundances measured at the beginning of the study.

Finally, hurricanes are natural phenomena that have accompanied all forms of life since geological times (millions of years!). Whether they are good or bad will depend on the preventive measures against their effects and how much we are contributing to making their damages more and more severe. With the current climate change, deforestation, the loss of beaches and mangroves, and the urbanization of high-risk areas (for example, flooding or mountain areas), we only increase the possibility of considering them as natural disasters.