Carbon and Oxygen Cycle
Photosynthesis
How do we get oxygen? The answer is a process called photosynthesis. All plants go through photosynthesis, where they take in carbon dioxide and water and produce oxygen and sugar for them to grow. The plants release oxygen not only for their own use, but for other animals as well.
Cellular Respiration
As heterotrophs, we eat to get our energy. We use that food with oxygen to make ATP, or cellular energy, and carbon dioxide in a process called cellular respiration. Without oxygen, we cannot make energy and we die.
The Carbon Cycle
The carbon dioxide we produce enters the carbon cycle, where carbon is converted between sources in the ground, living things and the air. Plants take in carbon dioxide during photosynthesis, removing it from the atmosphere. Right now, there is an excess amount of carbon dioxide in the atmosphere, causing global warming. Plants help counteract global warming because they lower atmospheric carbon dioxide. The plants use the atmospheric carbon dioxide to make sugar, in a process called carbon fixation. The carbon becomes part of the structure of plants.
Photosynthesis removes atmospheric carbon dioxide
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When the plants die, their structures decompose on the ground. Over time, the carbon becomes buried in layers and layers of soil. Geological processes compress the carbon, forming reserves of coal and oil. When people extract these natural resources, we burn them to make energy, which releases carbon dioxide into the atmosphere again. We are currently removing these solid reservoirs of carbon dioxide faster than they are being replaced, leading to increased atmospheric carbon dioxide and global warming. Trees play a valuable role in controlling this process.
Trees take in carbon dioxide in the carbon cycle
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Water Cycle
Plants need water to perform photosynthesis, and thus play a role in the water cycle as well. The water cycle is a process of moving water from the atmosphere, to the ground, to reservoirs and living things.
Water in the ground is taken up through the root systems in plants and delivered to other parts of the plant. Some water is used in photosynthesis, but some water evaporates into the atmosphere in a process called transpiration. Transpiration returns ground water to the atmosphere to continue the cycle.
Transpiration
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Without transpiration, water would simply sit in the ground. This can cause problems for soil health, and thus the organisms living there. It also presents a problem for rainfall. When water transpires in plants and is returned to the atmosphere, it helps form clouds and eventually rain. The rain redistributes the water to other places, providing an important resources for plants and animals all over the ecosystem.
Nutrition
Perhaps you're having a snack right now as you study. Where did your food come from? Even if you're eating beef jerky, the answer is plants. Plants provide all the food and energy needed to sustain an ecosystem. Some of your food, like fruits and vegetables, comes directly from plants. Wheat is processed into crackers and cookies. Carrots, soy beans, wheat and corn are all processed into feed for animals. The animals are then slaughtered to make meat products. So, even if you're a meat lover, your food still ultimately comes from plants.
Plants also provide food for animals in the ecosystem, not just us. Herbivores like rabbits eat only plants. Carnivores, like wolves, then feed on the herbivores. Plants sustain entire ecosystems made of hundreds of species in this way. Certain species, like bees, butterflies and hummingbirds, help maintain these cycles of nutrition by pollinating plants, or transferring pollen from stamen to pistil, so that these plants can continue to reproduce.
Plants sustain the entire ecosystem by providing energy in the form of food
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Habitats
Although we typically don't make a home out plants, many animals do. Trees provide shelter and shade. Birds make nests out of fallen branches and brush, situating them high in the tree canopy. Other animals burrow underneath trees, or live in fallen logs. Mushrooms make a life decomposing fallen plant debris. Predators use plants as cover for stalking their prey, such as lions in the grasses of the African savanna. Bugs use the green leaves as camouflage for hiding from predators.
Squirrels use trees as their home and food source
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Plants also absorb rain water, preventing excessive run-off that can ruin fields and deplete the soil of nutrients. Areas where clear cutting is prevalent, such as in the rainforest, exhibit a drastic loss of biodiversity. Habitats and food sources are destroyed and soil runoff prevents the land from being the rich reservoir of nutrients it once was.
Lesson Summary
Ecological services are the jobs that plants do in the ecosystem. Plants regulate the amount of oxygen in the atmosphere through photosynthesis, providing a necessary ingredient for heterotrophs to make energy. They also take in carbon dioxide to regulate the carbon cycle. They not only decrease atmospheric carbon dioxide but incorporate it into their structures, eventually returning it to the Earth when the plants die. This helps control carbon dioxide levels and prevent global warming. Plants regulate the water cycle through transpiration, which returns ground water to the atmosphere. Plants provide nutrition to people and their entire ecosystem, as well as create habitats and regulate soil runoff.
