Lesson Plan

• Describe why biomass productivity is low in arid regions.
• Explain how limited biodiversity reduces net primary production.
• Explain how restricted nutrient cycling limits soil fertility and plant growth.
• Analyse the feedback loop between vegetation and soil in arid environments.
• Evaluate land‑use implications of low productivity in desert landscapes.

• Projector and screen
• PowerPoint slides covering arid environments
• Printed handout of plant‑adaptation table
• Whiteboard and markers
• Images of arid‑soil samples
• Exit‑ticket cards

Begin with a striking photograph of a barren desert and ask students what they notice about the vegetation. Prompt them to recall previous lessons on net primary production and the factors that normally boost it. Explain that today they will identify the two key constraints—limited biodiversity and nutrient cycling—that keep arid productivity low, and they will know how to assess these in exam questions.

1. Do‑now (5'): Students list three factors that influence plant growth in dry climates; share responses.
2. Mini‑lecture (10'): Overview of arid environment characteristics and the biomass productivity formula (BP = NPP/Area).
3. Adaptation analysis (12'): In pairs, examine the printed adaptation table, discuss how each adaptation limits biomass, and record key points.
4. Soil nutrient cycle activity (10'): Using a diagram, trace nutrient flow, calculate the effect of low soil moisture on mineralisation rate, and discuss microbial constraints.
5. Case‑study discussion (8'): Explore land‑use challenges (overgrazing, salinisation) and link them to biodiversity and nutrient limits.
6. Formative quiz (5'): Quick Kahoot/quiz to check understanding of the two constraints.

Summarise that arid ecosystems have low biomass because few specialised species survive and nutrient cycling is sluggish, creating a reinforcing feedback. For the exit ticket, ask each student to write one way limited biodiversity and one way limited nutrient cycling reduce productivity. Assign a short homework: read the suggested article on desertification and prepare a one‑paragraph response on how sustainable land management could mitigate these constraints.