Biodiversity and Populations in Ecosystems

Biodiversity Biodiversity, or biological diversity, is the term we use to describe the variety of different species found on Earth. Biodiversity involves not only the number of different species but the variability in genetics, the ecosystems in which the organisms live, and the natural resources found in the ecosystems. All natural resources are connected, and all organisms are dependent on them. Therefore, it is safe to assume that any change, positive or negative, will have an impact on more than just one species or organism. All living things and their environments are interconnected. Why is biodiversity important? All living things depend on each other, and high biodiversity helps the sustainment of most species and strengthens their ability to withstand environmental change. Factors Affecting Biodiversity A balanced ecosystem, meaning an ecosystem maintaining itself over time through the emergence or migration of new species and loss of others, is ideal. Many different factors can affect biodiversity, including man and nature. Limiting Factors A limiting factor is anything in the environment that will limit the amount of organisms the environment can sustain. Limiting factors include, but are not limited to, space, water, food, and air. Space is a limiting factor in self-contained environments, such as a lake or pond. Biodiversity plays a great role in food as a limiting factor. Ecosystems high in biodiversity can support more life simply because there is more food. High biodiversity can also support a population because of the variety of food sources. For example, if a certain species of beetle feeds on a certain plant but that plants suffers a disease and dies out, a highly diverse environment would allow that beetle to go feed on another plant. Population Size Since some environments are conducive to population growth, some species will outgrow their environment. All ecosystems have a carrying capacity. This is the maximum amount of life a certain habitat can support. Most of the time, populations take care of staying below the carry capacity through immigration and emigration, but sometimes the population gets too high, and mass die-offs or even extinction can occur. Certain types of species play seemingly more important roles in an ecosystem than others. Keystone species are generally a predator that acts as a control on other population sizes. Fire ants are a good example of a keystone species. They keep insect populations under control. Without fire ants acting as a predator on certain insects, they might decimate the plant populations, leading to the destruction of habitats and food sources for other populations. Invasive species also play big roles in biodiversity. These are nonnative species that take over. An invasive species can move into an area that it is not naturally a part of and cause harm to its new home. Native species, or species that are naturally from that area, already have an established food web. Introducing a new species will throw off the balance of the food web, causing competition for food, habitat, and other resources. “The systematic removal of the gray wolf by the U.S.government is an excellent example of population disruption following the elimination of a keystone species. “The Chinese tallow tree is a highly invasive species that was originally introduced in 1776 to the American South. It competes with native trees for space and nutrients, eventually taking over native hardwood forest.” “Once the coral dies off, all that is left behind is the white, calcium carbonate skeleton.” Human Disturbance The Great Barrier Reef extends over 2,000 kilometers just off the northwestern Australian coast. It is the largest reef system on the planet and has been in a constant state of growth and development for thousands of years—until recently. Over the past two years, the reef has been steadily losing living coral, the basic reef-building organism. As coral disappears, so do many other populations, including fish, mollusks, marine mammals, and many more. The main culprits of coral bleaching—living coral dying off and leaving the reef to appear bright white—are ocean pollution, acidification, and rising ocean temperatures. To grow and thrive, most species of coral need clean, clear ocean water at just the right pH and temperature. Pollution makes the water murky and can choke out the sunlight that symbiotic, photosynthetic algae needs to feed the coral organism. Ocean acidification due to increase in carbon dioxide alters the pH of shallow waters, disrupting coral growth. Reflect Every living organism on the planet depends on its surroundings, living and nonliving alike, to sustain its life. Most organisms, including humans, do best in environments high in biodiversity. Imagine two types of forests. One has only one type of tree, a maple tree. Maple trees are deciduous, meaning they lose all of their leaves every winter. The other type of forest has many types of trees, including deciduous and evergreen. 1.Which of these forests could sustain more life? The forest with multiple tree species would sustain more life What do you think? There are many ways in which humans can help reduce negative impacts on biodiversity and help increase it instead. Sustaining biodiversity to maintain the ecosystem’s functions and productivity is essential to supporting and enhancing life on Earth. It also benefits humanity by preserving landscapes of recreational or inspirational value. 2.What are some actions you can personally take to reduce negative impacts on the ecosystem? Reduce waste, plant native species, conserve resources, and support conservation Application Determine the limiting factors that might exist in the example ecosystems below. 3. A community of mussels, starfish, and algae exist in a small tide pool. Space and oxygen availability are primary limiting factors 4. An oasis thrives around a small spring-fed pool in the middle of a desert. Water availability and space are primary limiting factors 5. A population of elk is reproducing rapidly in a section of forest due to the absence of any predators. Food supply and available territory are primary limiting factors