Pests and Biodiversity Loss

Overview

This is lesson 5 of 9 in Biodiversity on New Zealand Farms. Students use examples from New Zealand agricultural environments to explain how plant and animal pests can affect native species, habitats, food webs, production and ecosystem balance. They build on prior learning about biodiversity, sampling and ecosystem relationships by distinguishing observations from inferences.

Learning intentions

• WALT explain how plant and animal pests can affect biodiversity on New Zealand farms.
• WALT map cause-and-effect relationships between pests, habitats, native species, production and ecosystem balance.
• WALT distinguish an observation from an inference when interpreting evidence.
• WALT use scientific vocabulary to communicate an evidence-based explanation.

Success criteria

• I can identify a pest impact in an agricultural environment.
• I can explain a food-web or habitat consequence of that impact.
• I can distinguish an observation from an inference.
• I can link pest effects to biodiversity, production or ecosystem balance.

Curriculum links

• Biological Science — Ecosystems: human activity can cause habitat destruction and other changes that threaten ecosystem stability and biodiversity.
• Biological Science — Ecosystems: interpreting data, including maps and graphs, to evaluate how human activity influences ecosystem stability and biodiversity.
• Ecosystems: analysing distribution and abundance data helps scientists understand changes in populations and communities.
• Science capabilities: interpreting evidence, using scientific language, and communicating explanations.

Lesson structure (45 minutes)

1. 0–5 min · Hook and prior knowledge. Open with the hook and prior-knowledge slides showing a split image of a productive farm beside a grazed or weed-invaded habitat, then ask, “Can a farm be productive and still lose biodiversity?” Students make an individual prediction, discuss it with a partner, and share one possible pest impact.

2. 5–12 min · Direct teach: evidence and relationships. Use the pest-impact teaching slides to clarify plant pest, animal pest, native species, habitat, biodiversity, production, food web, observation and inference. Model an example such as: “The paddock edge contains fewer native seedlings” (observation) and “Browsing animals have reduced native plant regeneration” (inference). Students record the distinction and identify the evidence supporting the inference.

3. 12–27 min · Collaborative concept mapping. Place students in groups of three or four and distribute the pest-impact cards and concept-map worksheet. Each group selects or is allocated one New Zealand farm scenario, such as invasive weeds competing with native plants or introduced mammals browsing, predating or disturbing habitats. Students sort the information into observations and inferences, then map a chain using arrows: pest → immediate impact → habitat or food-web change → native species or biodiversity consequence → production or ecosystem-balance effect. They must include at least one piece of evidence and one uncertainty.

4. 27–35 min · Compare and improve explanations. Display the concept-map discussion slides and ask groups to compare their maps with another group. Students use two prompts: “Which arrow is best supported by evidence?” and “Where has the group made an inference?” They give one specific improvement, such as adding a missing habitat link or changing an overconfident claim to “may” or “could”.

5. 35–41 min · Individual application. Students complete the individual explanation on the pest-impact cards and concept-map worksheet: “Explain how one plant or animal pest could affect biodiversity on a New Zealand farm.” They must identify the pest, describe an observation, make a clearly labelled inference, and explain one food-web or habitat consequence. Students who finish early compare the likely effects of a plant pest and an animal pest on the same farm ecosystem.

6. 41–45 min · Plenary and exit check. Return to the plenary and exit-check slides. Students respond independently to: “A pest is present, but biodiversity has not necessarily decreased. What further evidence would you collect?” Invite two responses, then collect the worksheet or photograph completed concept maps for assessment.

Resources

• the complete pest-impact lesson deck
• the pest-impact cards and concept-map worksheet
• Whiteboard or interactive display
• Coloured pens or highlighters
• Large paper or group-sized copies of the concept-map page
• Access to teacher-read or audio versions of the worksheet text
• Timer

Assessment

• Listen for accurate use of observation and inference during group sorting; ask, “What did you actually observe, and what are you concluding from it?”
• Check concept maps for a logical pest-to-impact-to-biodiversity chain, appropriate arrows, evidence and cautious scientific language.
• Use the individual explanation and plenary response as formative evidence of whether students can explain a habitat or food-web consequence and identify further evidence needed.

Differentiation

• Provide illustrated pest-impact cards, a partially completed concept map, colour-coded arrow labels and sentence starters: “The observation is…”, “This suggests…”, and “As a result, the habitat/food web…”.
• Pre-teach vocabulary with simple definitions and visuals; allow students to rehearse oral explanations before writing. Pair students strategically and assign roles such as reader, evidence finder, mapper and reporter.
• Offer the worksheet text as an audio recording or teacher-read version, use a dyslexia-friendly font and spacing, and accept labelled diagrams or recorded oral explanations where appropriate.
• Extend confident learners by requiring comparison of a plant pest and an animal pest in the same farm ecosystem, including one similarity, one difference and a judgement about which impact is more likely to reduce biodiversity.

Extension

• Compare the likely effects of a plant pest and an animal pest on a selected farm ecosystem. Identify which evidence would be needed to test the comparison.
• Propose one realistic monitoring measure a farmer or ecologist could use to track changes in native species, habitat condition or production.