Well, obviously, a volcanic eruption results in chaos and people don’t run around in a panic for no reason. Besides the river of molten rock, there are also high concentrations of gases and volcanic ash being released. The gases and ash are usually (at least partly) relocated by the winds. While the gases can travel around the globe, ash usually falls down soon, due to its weight. The presence of ash can greatly influence the health of the plants living in the area. If we are talking about a thick layer of ash, it kills the plants (due to lack of sunlight) and when talking about a thin layer it acts as a nutrient boost. The situation with the presence of the molten rock (that can reach 800-1200 °C) is quite straightforward – it covers the existing ecosystem and kills or burns many organisms along the way.
How does the life come back?
It does so with a process called primary succession. We talk about it, when an area becomes completely devastated or when (due to changes in the environment) the organisms occupy a new area. A good example of this is the upward movement of the trees at the mountain tops. In order to meet the criteria with which we define primary succession, the complete absence of life is required (no spores, seeds, etc.). At this point, you are maybe wondering why I didn’t mention the wildfires? Its because after them, there are some survivors (fire resistant plants, seeds etc.) left. Because of this the germination and growing process take place very soon (sometimes only a week) after the event. Wildfires (as well as deforested areas) are therefore an example of so-called secondary succession.
There are many volcanoes and through the Earth’s lifetime, there have been many volcanic eruptions. We have researched many eruptions on land (such as St. Helens, or Vezuv) as well as formations of new islands (such as Surtsey or Tonga island). The location of the volcanic eruption as well as different direct and indirect factors greatly influence the speed of primary succession. Let’s go see some examples.
Formation of a new island
After the formation of a new island, there is literally nothing besides the molten rock. In order to bring life to this deserted place, three steps are followed: colonization, establishing of the living conditions and development of biotic interactions. The speed of colonization is highly related to temperature (high temperatures, higher succession rate) and distance from other occupied lands (or islands). When the distance is small, the succession will happen fast and if distances are great it will happen slowly. However, the conditions that will support life and will attract organisms are closely related to colonization process.
One of the most important processes is the (water and wind) erosion. With this natural phenomenon, cracks in the molten rock form, which enable the accumulation of substrate (soil and sand). These newly formed microhabitats can easily hold moisture, which is very important for the germination process. As the plants grow, they release organic acids and chelates, that literally dissolve the rock. With this, the plant gets almost all the nutrients it needs (Silicium (Si), Aluminium (Al), Iron (Fe), Magnesium (Mg), calcium (Ca), sodium (Na), potassium (K) and phosphorous (P)). The only remaining problem is the lack of the carbon (C) and nitrogen (N). However, they become very abundant when pioneer species (most often birds, grasses or insects) come into the picture. The biggest source of C and N is the feces, but there is also plenty of other sources such as seeds, pollen, spores, and rain.
The pioneer species have broad ecological niches, which makes them perfect to start the life in the unfriendly environment. While living conditions are getting better and better, the diversity of organisms is slowly increasing. These new species are usually specialized for a certain ecological niche (can take up more nutrients, quicker growth, better prey-catching techniques) and will slowly dislodge the pioneer species. In time, the ecosystem becomes as adapted as it can be to the given conditions and we say, it has reached the climax stadium.
Volcanic eruptions on land
When an eruption on land occur, the damage done can be enormous (especially when talking about volcanoes, that have cities right under their feet). However, these ecosystems can be re-establish a lot quicker than they are after a formation of a new island. The reasons behind this are actually very simple – short distances and empty ecological niches.
The concept of an empty ecological niche is quite easy to explain – since the land is empty, there is no one you need to compete with in order to get your space. However, the ”locked” nutrients might present a problem, and therefore only the organisms that need very little of them can occupy the empty ecological niche. It can also happen, that the river of the molten rock didn’t reach or avoided some land (for example spaces behind big rocks, hills etc.). These areas are called refugees and are usually used as a strategic position by plants. Here, they can easily establish big populations and when the conditions get better, they can easier expand and occupy the new area.
What do you think about volcanoes and newly formed islands? Have you ever seen a volcano with your own eyes? Which one and how did you feel looking it the eye of it? Let me know your story down below – I would be very happy to read it!