Los Angeles County contains a vast variety of ecosystems, thanks to its mix of mountains, valleys, coastal plains, and river systems. The combination of rugged landscapes and proximity to the Pacific Ocean and major rivers creates diverse climates and habitats — making LA one of the most ecologically rich regions in the country.
Ecology is the study of how living things interact — with each other and with their environment. It looks at the relationships between plants, animals, fungi, and microbes, and how they connect with non-living elements like sunlight, soil, water, and air. Rather than focusing on just one species, ecology helps us understand the bigger picture — how life works as an interconnected system.
All life on the planet lives in Earth’s thin crust in a region that scientists call the biosphere. The biosphere is the largest ecosystem, containing all the living things on Earth and their environments. The biosphere includes all the places where life exists. This includes where life is found deep within the ocean, to the tall mountaintops reaching towards the sky.
In order to understand the biosphere, scientists study how it is organized. The building blocks go something like this:
Individual: An individual is the most basic building block in ecology. It can be as small as a single bacteria, a starfish, tree, a bird, or even you.
Species: A group of individual organisms that share similar traits, which allows them to breed and produce young. Examples of species include mountain lions or hawks.
Population: A group of individuals of the same species living in the same place at the same time.
Community: Different populations of species that live together in a certain area. Populations of species within a community interact with each other in different ways.
Ecosystem: Describes relationships between different communities and their physical environment in an area. There are many ecosystems in Los Angeles County.
Biome: A large region made up of several ecosystems, characterized by its location on earth, its plant life, soil, and regional temperature and rainfall patterns.
Los Angeles sits within a Mediterranean biome, one of only five such regions in the world. Defined by hot, dry summers and mild, wet winters, with drought-tolerant vegetation and periodic wildfire cycles.
Biosphere: Where all life exists — from the deepest ocean trenches to the highest mountain peaks. It includes every ecosystem on land and in water: forests, deserts, grasslands, wetlands, and oceans.
An ecosystem is not one particular place; it is a system of relationships between living things, such as plants, animals, fungi, and bacteria, and non-living elements such as sunlight, water, air, soil, temperature, and rocks.
These components are constantly interacting to keep the system healthy and in balance. Organisms need the right conditions—enough food, clean water, space, and a stable climate—to survive, grow, and reproduce. In a well-functioning ecosystem, everything is interconnected in a dynamic, self-regulating system that naturally tends toward equilibrium.
Unlike human-made systems, nature does not produce excess or waste what it doesn’t need. Every element—whether a plant, animal, microbe, or fungus—has a role that supports the whole. This balance is what allows life to thrive.
For example, organic matter that dies becomes nutrients for other organisms. Populations rise and fall in response to available resources, predators, and environmental conditions, helping to prevent unchecked growth or depletion. Nothing exists in isolation, and there is no concept of “extra”—every output is an input for something else. This closed-loop efficiency ensures that ecosystems sustain themselves over time without exhausting the natural systems they depend on.
Note: In Western science, ecosystems are typically described in terms of living and non-living components. However, in many Indigenous cultures, this separation doesn’t exist in the same way. Instead, all elements of the natural world – including soil, rocks, water, and the sun – are understood to have spirit, life, or agency.
This worldview reflects a deep sense of connection, respect, and responsibility toward the land – reminding us that there are many ways to understand and relate to nature beyond scientific classification.