Fleeing the heat, higher and deeper

2008/09/01 Elhuyar Zientzia Iturria: Elhuyar aldizkaria

• Ekologia
• Klima
• Ingurumena

Near Dévoluy (French Alps) is the Bure peak. On the slopes of the mountain are forests of various plant species. In the lower right corner of the image, a mosaic of large photographs shows the forest ecosystems. From bottom to top you can see the distribution by altitude, starting with the lower shelves towards the high mountains, and from left to right according to the latitude, from the Mediterranean forest to the temperate forest. çIn the mosaic of small photographs appear several species of plants growing in the forests of the western mountains of Europe.

(Photo: J. Lenoir/Science)

Scientists have shown in different parts of the world that global warming is pushing species to migrate, both in latitude (polar), altitude (mountain up), and depth (sea).

Recently, two representative examples of these migrations have been published in two scientific journals: Science with forest plants and Journal of Applied Ecology with fish. In the first, researchers have tested the XX. In the eighteenth century there was an increase in optimal plant habitat, with an average increase of 29 meters per decade. In the other, it has been proven that the fish of the North Sea live 9 meters deeper than 25 years ago.

Top mount oak

French and Chilean researchers have jointly conducted a study on forest plants. Six mountain ranges from Western Europe (the Norpirenean slope, the Western Alps, the Central Massif, the Western Jura, Vosges and the Corsica mountain range) have been selected and, at a height of 0-2,600 metres, in Mediterranean and temperate forests during the 20th century. Data on species growing in the 19th century have been analyzed.

In fact, in this century the increase in temperatures in France has been higher than average. Specifically, the temperature has risen more than 0.6°C in XX. In the 20th century, the rise has been even more pronounced since the 1980s, especially in the surroundings of the Alps, where it has risen almost 1 ° C.

To see the influence of this warming on plants, data on 171 species from two inventories from 1905-1985 and 1980 have been analyzed. Thus, it has been shown that the optimal habitat of all species is above the above. However, not everyone has migrated at the same speed, which has meant a change in plant communities.

In this satellite image you can see the plankton bloom in the North Sea.

ANDÉN

For example, herbaceous and short-lived plants have increased rapidly leaving slow-growing species like the white fir behind. In addition, mountain species, such as the basalors of the Alps, have increased more easily than those living elsewhere (juniper). As a result, researchers fear that ecological networks will be broken and that changes and losses will occur in the interaction between animals and plants.

Deep water

Global warming also affects fish species in the North Sea. According to the measurements of the last 25 years, the temperature in the seabed has risen 1.6°C in the North Sea, and scientists believed that species would migrate north. Now, however, British researchers have seen that instead they sink. They live at an average depth of 9 meters and there are species that have dropped 35 meters, such as the Lepidorhombus whiffiagonus.

Researchers are convinced that this phenomenon is due to global warming and not to the pressure of fishing, as species that are not fished now live deeper than before.