- Students brainstorm invasive plants that they know about.
- Students work in groups to identify invasive plants along a trail or transect.
- Students estimate abundance & infestation rates in a quadrant along a transect.
- Students explore herbivory rates on invasive plant leaves and compare them to native plant herbivory rates.
- Students share their results. Optional: Students add their data to the NY iMap Invasive Species database.
Day 2: Invasive Plant Survey
Students will know what invasive plants exist in their area and will be able to identify several along a trail or transect.
- Laminated sets of invasive plant cards (the cards on this website are suitable for the Mid-Hudson Valley; plants may need to be added or removed depending on your geographic location)
- Copies of student lab sheet
- Measuring tape
- Transparency sheets cut into 4x6 inch cards with 1cm square grid.
- Baggies for students to collect leaves
Engage: Ask students to name as many invasive plants as they can; most students know at least one plant, even if it is not from their local area. Make a list on the board.
Explore: Hand out a copy of the invasive plant cards to groups of students, along with the student handout. Give them enough time to explore a trail or forest edge near the schoolyard. Instruct students in how to positively identify poison ivy and point out any known patches. Also remind them of general safety procedures in the field, including checking themselves for ticks after walking through woods or tall grass.
Set up a transect along which students can measure out small quadrants. Depending on the size of your class, you may want to have more than one transect, or a longer transect. You can have students investigate one quadrant, or more than one, depending on how much time you have available. In each quadrant, students identify the invasive plants present (if any), estimate the abundance of the invasive plant, and identify the habitat type.
Finally, students estimate the percent herbivory of invasive and native plants by collecting ten leaves from different native and invasive plants. Instruct students NOT to take more than one leaf from a plant and NO leaves from any plant with four leaves or fewer. Remind them that leaves are the food-production factories for plants. Taking the leaves back to the classroom, the students use the transparency sheets with the grids to estimate how much herbivory has taken place. Any herbivory should be counted, but fungal damage should not.
Explain: Invasive plants are a problem throughout the world, and New York harbors a large number due to the high volume of shipping traffic in the state. Although some invasive plants continue to be sold in garden centers and nurseries, awareness is helping reduce the incidence of accidental introductions. Invasive plants tend to be successful because they reproduce in high numbers, can tolerate a range of soil types and weather conditions, and generally are free of natural predators found in their native range. While there is some evidence that native predators eventually learn how to eat invasive plants, some species are well protected (such as Japanese barberry, which has lots of thorns) or are toxic to competitors (such as Tree of Heaven, which emits toxins through its roots). Generally, native plants suffer higher rates of herbivory than invasive species. Different areas in New York have different invasive plant problems, but invasive plants continue to spread into new areas.
Extend: Students can upload their results to iMap Invasives (NY iMap Invasive Species), where their data will be added to others’ in our region and made available to help land managers develop better invasive management strategies.
Evaluate: Collect student lab sheets.