Human Impacts on Earth’s Systems JT8.png

Lesson 2: Invasive Species


The severe desert environment and increasing temperatures can make it tough for plants and animals to live in Joshua Tree National Park. We discussed yesterday in class, that as temperatures increase plants cannot move to hide from the sun or seek water elsewhere like animals can. Although the desert is characterized by hot temperatures, low soil nutrients and low amounts of water, there is a diversity of plants who have adapted to these conditions. But some of the plants found in Joshua Tree National Park do not belong there, meaning they did not evolve in the area and are non-native. They are called invasive species and can upset ecological dynamics in the places that they live.



Native species, invasive species, adaptation, environmental impact

Captivate & Collaborate:

Teacher Says/Does

Open Questions

Student Answers

Teachers begin this lesson with a class discussion about animals. Use the supplementary pictures of SeaWorld’s animals and the surrounding environment.

Teacher records student responses to questions on the board.

2. Ask students to think, pair, share what they believe happens when non-native plants and animals are introduced to a new habitat. Provide an example.

1. Ask students to think about Seaworld. How do the animals get there? Are they native to the habitat there?

2.What could happen when animals or plants from the rainforest end up in the desert?

1. Introduced by humans. They are not native.

2. When non-native plants and animals are introduced to a new habitat there are many possible issues that may arise. The biggest issue is the loss of habitat when non-native species are introduced into an ecosystem.
Non-native species can also harm an ecosystem by taking resources away from endemic organisms.


Teacher Says/Does

Open Questions

Student Answers

3.Some plants found in the desert today, such as red brome (Bromus madritensis) do not belong in the desert. They were introduced from other countries and are called non-native species or invasive species.

Explain how non-native plants and animals often have the ability to grow and flourish in new environments because their usual predators are not there. These plants and animals are called invasive species.

Inform students that invasive species are harmful because without natural controls or predators they can rapidly spread and overtake areas, competing with native species for precious resources (water, nutrients, space).

3.What are invasive species?

3. An invasive species is an organism that is not naturally found in the given area.

Red brome:

Red brome, also known as foxtail chess and foxtail brome, is a native annual grass to the Mediterranean region.

Red brome is an invasive grass that has become a huge issue in desert ecosystems. Red brome seeds require about half as much water as most plants native to Joshua Tree National Park. Because it can better survive the dry, hot conditions it easily takes over the ecosystems and makes it very difficult for native plants to live.

Red brome carries fire...

Explain that desert plants are not adapted to fire and their seeds do not require fire to re-sprout.

Discuss how fires in Joshua Tree National Park used to occur only every century. Now we are seeing fires every 30 years in the Mojave.

Now VS Then...

During the moist El Nino year in the 1990s, red brome spread quickly through Joshua Tree National Park. Also, scientists have found that nitrogen pollution from all of the cars being driven in Los Angeles can blow into Joshua tree and fertilize the soils which are also contributing to red brome spread.

Before this happened, when lightning hit a Joshua Tree it would burn the tree then the fire would go out, or have less chance of rapidly spreading. However, now that the red brome covers the ground it is able to carry the fire from the ignited plant to others by burning through the red brome.

The presence of red brome increases fire intensity and burn speed. Red brome alters the fire patterns in Joshua Tree National park and is especially harmful to other desert plants that are not adapted to such fires.


Teacher Says/Does

Open Questions

Student Answers

Have students get into groups of 3 or 4 to research other invasive species in any national park. After researching, students will make a poster that answers the following questions with an emphasis on humans impacts on Earth's systems (ESS3.C).

Poster research questions:

1. What is an invasive species? (Answer the question and draw a before and after picture to illustrate).

2. How have they been introduced to new environments?

3. Why is it important not to bring non-native species to new environments?

4. What can we do to reduce invasive species in natural habitats and protected areas?

1. According to the National Park Service, invasive non-native plants are defined as plant species that have been introduced to an ecosystem after European contact as a direct or indirect result of human activity.https://park

2. Invasive species are introduced to new environments in many different ways. Some are introduced intentionally by humans, some are brought as unsuccessful attempts to control other invasive species and/or transported accidentally though shipping. *There are other correct answers.

3. There are many reasons why we do not want to bring invasive species to new environments. A few reasons are: destroyed habitat, increased competition for native species, difficult/impossible for native species to get resources, kill off native species, impacts on human health etc.

4. In an attempt to reduce the number of invasive species, we must educate people to prevent further spread of invasive species and conduct more research. There are specific physical, cultural, biological and chemical controls that are already in use. see chart in supplementary materials sections

Supplementary Materials:

Link to powerpoint slides “Lesson 2 - Invasive Species - with pictures

Background information on red brome:

Field Guide for Managing red brome in Southwest: