Table of Contents
Pioneer Species Definition
Pioneer Species are those organisms that begin the formation of an ecological community in a region where no living forms currently exist.
What is a Pioneer Species?
Areas that are completely barren, devoid of nutrients, and inhospitable provide slim (to none) possibilities for any living form to establish itself. But to the rescue comes the resilient, photosynthetic, widespread, fast-reproducing, orthodox-seeded pioneer community, with high dispersibility rates, shorter life cycles, and great tolerance…
So, if someone asks us to describe pioneer species, we can quickly describe their basic characteristics and explain how ecological succession occurs.
In primary succession, pioneer species are the first to colonise a bare substrate, whereas in secondary succession, they are the first to colonise a devastated environment.
(1) a pioneer lyme grass (Leymus arenarius) on a sand-covered plain,
(2) pioneer plant species (e.g. swordfern, Polystichum munitum, and the moss Racomitrium ericoides) that thrived in a newly formed habitat created by a solidified lava flow, and
(3) pioneer plant species that colonised an area that had been cleared.
Pioneer Species Example
A thorough collection of instances has been compiled. To learn more about them, look at the image below. Pioneer germs, fungi, and animals only enter when pioneer flora and lichens have mastered their tasks. Soil invertebrates such as ants, worms, and snails, as well as some toads, are examples of pioneer fauna.
The Sword Fern (Polystichum munitum) is a Pteridophyta pioneer.
Features of Pioneer Species
1. Hardy in nature: Pioneer species are able to endure and trade in a variety of severe environmental circumstances.
2. Seeds- Orthodox and easy to germinate: Pioneer species have orthodox seeds, which are “seeds with less than 5% total moisture content that are nonetheless alive and have remarkable longevity.” This property aids pioneer species in reproducing even after years of hibernation. Desiccation is not a problem for them, and they may produce new plants following germination. These seeds are unaffected by low moisture content.
3. Seed Germination- Light-Induced: The seeds of pioneer species are often “photoblastic,” meaning they germinate when light is stimulated. Any seed will germinate if it is given ideal moisture, nutritional, and other environmental circumstances, but these seeds don’t have much demand in desolate regions. Their only requirement for germination has evolved to be “light stimulation.”
4. Life Cycle- Short: Any biological body is created with the ultimate goal of “species perpetuation” in mind. Pioneer species have evolved to have a brief life cycle since desolate environments give little opportunity for any creature to enjoy a happy time for a long time. This is a sign that they are in the early stages of their reproductive lives. Pioneer species reach reproductive maturity quickly, regardless of how they generate progeny (sexual or asexual).
5. Pollination and Seed Dispersal- Both via wind: In the same way that an unfriendly habitat is bad for any species, it is also bad for pollinators (whether they are birds, insects, bats, or animals). Wind pollination is the only viable option. The majority of sexually reproducing pioneer species, for whom pollination is an important stage in gamete fertilisation, are pollinated by the wind. Furthermore, the wind is used to disperse their seeds.
6. Rates of Seed Production and Dispersal- High: Pioneer species’ seeds are extremely viable, generated in a geometric pattern (in huge numbers), and have a high dispersion rate. Such dispersion rates are required to colonise a nutrient-deficient terrain.
7. Propagule Size- Small: Small propagules make it easier to disperse and achieve succession goals. Small seed or propagule size also enhances germination chances since they can get “caught” in small cracks, holes, and traps during hostile periods.
8. Wide Range- Both ecological and geographical: This broadens the distribution and helps primary succession in regions impacted by a variety of causes.
9. Major Mode of Reproduction- Asexual > Sexual: Because sexual reproduction is more energy-intensive and time-consuming, it isn’t truly a viable option for pioneer species. Although there are certain animals that have a sexual mode. The asexual mode, on the other hand, is more popular due to the benefits it provides.
Certain lichens and algae are widespread species that can thrive in a variety of environments, making them the most common pioneer species, or initial settlers, after a disturbance. Because the new environment is likely to have soil with fewer nutrients and be primarily exposed to light energy, the pioneer plant species are often photosynthetic.
It’s also more likely that wind pollination is used by pioneer plant species. Furthermore, rather than sexual reproduction, most people reproduce asexually. The pioneer species may eventually give nutrients to the soil, resulting in a better environment for the following species.
Pioneer Species and Ecological Succession
It is critical to comprehend ecological systems, the formation of ecological communities, and ecological successions in order to create conceptual clarity about pioneer species. The biological interactions between the many parts of the natural system, as well as their various interrelationships, are referred to as ecological systems.
The way an ecological system is constructed influences how it will work, as well as its fundamental requirements, long-term viability, and success. An ecological community is based on how “often” certain species occur together in a given region.
The species share comparable environmental conditions and resource scarcity/abundance. The community’s equilibrium is determined by how they affect one another. All variables, processes, and interrelationships within a community that regulate its evolution across time are referred to as ecological succession. It is primarily concerned with the “structural” evolution of a biological community through time.
Every physical, chemical, and biological entity changes over time, and ecological succession describes these changes. “Changes in community skeleton” – how different species evolve, how one’s evolution affects another’s, how coevolution occurs, and how organisms gradually adapt to thrive in harsh environments.
Types of Ecological Successions
i. Primary Succession
Primary succession occurs when an organism lives, thrives, and reproduces in a region where no other organism has ever lived, flourished, or reproduced.
Only pioneer creatures, especially “only pioneer plants,” can lead to the establishment of a friendly habitat in this case. Characteristics of every pioneer organism capable of bringing about primary succession:
1. Any barren area would be devoid of pre-existing organic compounds, making organic compound oxidation for energy purposes impossible.
2. Because there are no pre-existing autotrophs on barren ground, the heterotrophic mechanism of carbon derivation is clearly removed.
3. Any desolate terrain would almost certainly lack any biological source of electrons (even inorganic ones are unlikely… But if some minuscule probability is included, it’s still only an inorganic source!).
As a result, in primary succession, the pioneer species must be a plant—a photo-auto-lithotroph. They colonise bare surfaces (without soil) and then form ecological communities.
Primary Succession Examples
Photo-auto-lithotrophs include only plants and a specific type of algae known as “blue green algae/Cyanobacteria.” As a result, they are the only pioneer species responsible for initial succession. Apocalyptic habitat loss occurs in areas impacted by large landslides, fires, volcanic eruptions, or flooding. The topsoil and layers underneath it are eroding in certain locations.
There is no energy/carbon/electron source remaining in such regions that can support life other than photo-auto-lithotrophic life. Another aspect worth mentioning is the “essence of a finite resource-NITROGEN.” As a result, several of these pioneers fixed nitrogen.
Because they are photo-auto-lithotrophic and nitrogen-fixing, cyanobacteria are primarily responsible for primary succession in the most severe environments.
Lichens are the first species to appear in primary succession, and they have the unique ability to colonise bare rocky surfaces.
ii. Secondary Succession
Unlike the barren and previously deserted places, certain areas require re-establishment following a disturbance that “wiped away” a full-fledged natural population. The secondary succession is this re-establishment. Some soil and previously existing plants are still present in these locations. There are fewer resource battles in these regions, and pioneer species have an advantage.
We can list angiosperm trees and shrubs as pioneer species in secondary succession if requested. These have some of the highest growth and community development rates in the country. Pioneer species in secondary succession are not required to be photo-auto-lithotrophic.
Secondary Succession Example
Microbial and invertebrate taxa have just recently been added to the pioneer species list. Photo/chemo, auto/hetero, litho/organo trophs are all possibilities. This emphasises an essential point: secondary succession occurs in areas where certain nutrients are already present in the substrate.
Secondary succession occurs in places like deforested regions, logged woods, wind-affected areas, and so on. As a result, numerous microbiological species (bacteria, archaea), invertebrates, and tree species, such as Betula spp. (birch tree species) and Alnus spp. (alder tree species), serve as pioneer species in secondary succession.
An Interesting Fact About Pioneer Species
Did you know that the 1986 Chernobyl Nuclear Power Plant Disaster in Pripyat, Soviet Union, which displaced humans, animals, and other species, gave birth to a new fungus that “feeds on radiation”? Yes… Scientists investigating the region discovered “a pioneer fungus” that is an extremophile suited to strong radiation and has a remarkable capacity to eat it rather than be harmed by it (unlike other organisms).
This fungus species is pushed to the most severe radioactive locations, similar to how plants exhibit phototropism (the ability to be driven towards a light source). This species’ main and secondary metabolic products, which have incredible lytic and enzymatic activity, provide this quality! Who knows how many more pioneer species have been generated and are still being investigated in that catastrophic place… How many more pioneers will be born as a result of this?
Pioneer Species Citations
- How lichens impact on terrestrial community and ecosystem properties. Biol Rev Camb Philos Soc . 2017 Aug;92(3):1720-1738.
- Changes through time: integrating microorganisms into the study of succession. Res Microbiol . 2010 Oct;161(8):635-42.
- Gopher mounds decrease nutrient cycling rates and increase adjacent vegetation in volcanic primary succession. Oecologia . 2014 Dec;176(4):1135-50.