Volcanism, Plate Tectonics, and Biosphere Concepts
Volcanism in the Canary Islands
While mainland Spain has three extinct volcanic areas, the Canary Islands have experienced seventeen historical eruptions. The most significant eruption occurred in Timanfaya in 1730. The latest eruption took place in La Palma-Fuencaliente in 1971. Tenerife leads in the number of eruptions, with the most recent one occurring in 1909 (Badlands). Eruptive periods range from 1 to 273 years, averaging 30 years. The eruptions are typically of the explosive alkaline basalt type.
Wilson Cycle
This cycle proposes that every 400-500 million years, all landmasses merge to form a supercontinent. The most recent supercontinent was Pangea. The disintegration and subsequent collisions of plates are linked to the Hercynian Orogeny, which played a crucial role in shaping landforms.
Pangea
Continents, embedded in mobile lithospheric plates, are constantly shifting. Oceanic plates can subduct and disappear into the mantle, driving plate movement. However, continental plates are too rigid and thick to subduct. When two continents collide, they merge, forming mountain ranges. In Earth’s history, most continents have converged multiple times, forming supercontinents like Pangea. The last such occurrence was between the late Paleozoic and early Mesozoic eras.
Biosphere
The biosphere is the layer of Earth where living organisms exist. It interacts with the other three subsystems: the geosphere, hydrosphere, and atmosphere.
Ecosystem
An ecosystem is an area within the biosphere where living organisms interact and exchange matter and energy with their physical environment.
Ecosphere
The ecosphere encompasses all ecosystems on Earth.
Biotic and Abiotic Factors
Biotic factors (biocenosis) comprise the living organisms within an ecosystem. Abiotic factors (biotope) include the physical and chemical components of the ecosystem, such as temperature, precipitation, and light.
Trophic Pyramids
These pyramids represent the flow of energy between different trophic levels. Pyramids of numbers show the number of individuals at each level, while energy pyramids illustrate the energy transfer.
Law of the Minimum
Plant growth is limited by the scarcest essential resource, which acts as a limiting factor.
Production Strategies
- R-strategists: These organisms have high biotic potential, producing numerous offspring with minimal parental care (e.g., insects and fish).
- K-strategists: These organisms have lower reproductive rates but provide significant parental care, resulting in higher offspring survival rates (e.g., mammals and oak trees).
Valence
Valence, or ecological tolerance, refers to the range of an environmental factor (e.g., light, temperature) that a species can tolerate.
Predator-Prey Model
This model is stabilizing due to its inherent negative feedback loop.
Niche Competition
Competition arises when individuals of one or more species vie for the same limited resource. The ecological niche defines a species’ role within an ecosystem, encompassing its interactions with the environment, trophic connections, and ecological functions.
Biodiversity
- Species Diversity: The variety of species on Earth, considering both the number of species and the abundance of individuals within each species.
- Ecosystem Diversity: The variety of ecosystems on Earth, including terrestrial and aquatic environments.
- Genetic Diversity: The genetic variation within and between species, enabling adaptation and evolution.
Limiting Factors of Production
- Temperature: Higher temperatures generally accelerate plant growth, but excessive temperatures can increase respiration more than primary production, potentially reducing net production.
- Moisture: Water scarcity hinders photosynthesis in terrestrial plants. Stomata closure reduces CO2 uptake and can lead to photorespiration, particularly in C3 plants.
- Nutrients: Essential for building organic matter, nutrients like nitrogen and phosphorus can limit primary production.
- Light: Crucial for plant growth, light intensity influences primary production. However, beyond a certain threshold, further increases in light intensity do not enhance production.