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Native Soil

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Fire is an important way for an ecosystem to rebuild itself. Unchecked undergrowth made up of opportunistic weedy plants robs vital water and soil; nutrients normally available to the large stands of older hardwood trees so important to the wildlife that populates the ecosystem. So while man-made forest fires can devastate large parcels of land, causing irreparable harm to the ecosystem, smaller naturally started fires can actually be helpful, ridding the area of unchecked weedy undergrowth, making it more hospitable for the trees and allowing wildlife to flourish.

Scientists are now learning that the dying undergrowth is also helping the ecosystem in another way. The smoke and ash from these natural fires contain chemicals which they believe remain in the soil and aid in the regrowth of the forest. One such family of these chemicals is the karrakins. Karrakins are believed to help the rebirth of a burned forest by aiding in seed germination.

The first experiment involved the karrakins ability to increase the number of seeds that germinate as well as to speed up germination time of various seed plants. The design involved using various members of a typical forest ecosystem, including prickerweed, a pine tree and a beech tree seeds.

Each group contained 50 beech seeds, placed in native soil and watered the same amount on a regular schedule. Treatments are described below:

Group 1-Water only

Group 2-Ash from a burnt prickerweed and water

Group 3-Ash from a pine tree and water

Group 4-Purified karrakin extract at a concentration of 20 ug/ml and water

Group 5-Purifed karrakin extract at a concentration of 40ug/ml and water

Group # # of germinated seeds Time to first seed germinating (days) Ave time for seeds to germinate (days)
1 28 2.3 3.7
2 39 1.6 2.7
3 28 2.7 4.5
4 44 1.2 2.2
5 48 .9 1.9

Why is the use of native soil important to the overall experiment?

A

Native soil acts as a control when comparing the number of seeds used.

B

Native soil acts as a control when comparing the amount of water each seed group was given.

C

Changing the soil would act as a second experimental variable.

D

Native soil won’t allow the seeds to germinate without the presence of karrakins.