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SEEd - Grade 7
Strand 7.4: Reproduction and Inheritance 7.4.2
1 class periods of 60 minutes each
Thinking & Reasoning
By measuring how fast seeds fall, students will calculate how far a single a generation of plants can disperse by wind. Then they can apply these findings to speculate on plant species movement and survival as a result of biome shifts predicted with climate change.
Seed dispersal is the primary means by which plant species ranges can change with time. Seeds are dispersed by many agents. This lesson focuses on wind-dispersed seeds. Plants are adapted to a range of temperatures and precipitation regimes that define a biome, but climate change is expected to shift biome distributions. Specifically, biomes are expected to shift poleward and upslope.
1. Use Science Process and Thinking Skills
This activity can catalyze further discussion about the effects of climate change on natural ecosystems. For example, many plants have animal-dispersed seeds. Will these plant species be affected the same way as wind-dispersed plants? (The distance that animal-dispersed seeds can travel is limited by how far their dispersers move them. Depending how the animals that disperse seeds are affected by climate change, they might be expected to move seeds to areas with adequate climates or not.) As biomes shift in response to climate change, how might urban and agricultural areas affect this process? (These areas may impede plants and animals from reaching areas with adequate climates.) What can wildlife managers do to ensure that species do not go extinct because of climate change? (Protect land areas that provide corridors for the movement of wildlife, transplant wildlife to areas with adequate climates.)
Assessment can be adapted to the goals of the teacher. The calculations may be finished during class time. Discussion question can be assigned as homework or discussed during the lesson.
Augspurger, C. K. 1986. Morphology and dispersal potential of wind-dispersed diaspores of Neotropical trees. American Journal of Botany 73:353-363.