In the Hubbard Brook Experimental Forest in New Hampshire,a Portion

question 19

Multiple Choice

In the Hubbard Brook Experimental Forest in New Hampshire,a portion of the forest was first clear-cut,then sprayed with herbicides for 3 years to prevent growth.A second portion of the forest was not clear-cut or sprayed and served as a control plot.The following graph shows that nitrate,a form of nitrogen that is important to plants,was lost from the ecosystem in streams at a much higher rate in the clear-cut portion of the forest than in the control portion.

What best explains the small releases of nitrogen from the control portion of the forest at the Hubbard Brook Experimental Forest?

• A) Its nitrogen was sequestered in the forest biomass and temporarily unavailable.
• B) With intact vegetation to intercept the acid rain that falls in the area,it failed to reach the soil and chemically react to release the nitrogen.
• C) With intact vegetation,rainwater washed little soil and nitrogen from the forest floor.
• D) Pesticides from the clear-cut areas seeped into the control area.

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Definitions:

Lichens

Symbiotic partnerships between a fungus and an alga or a cyanobacterium, capable of surviving in harsh environmental conditions and playing a role in ecosystem nutrient cycles.

Clownfish

Brightly colored fish known for their symbiotic relationship with sea anemones, inhabiting the warm waters of the Pacific and Indian Oceans.

Catastrophic

Involving or causing sudden great damage or suffering, typically on a large scale or involving a natural disaster.

Drought

Drought is a prolonged period of abnormally low rainfall, leading to a shortage of water that adversely affects crops, animals, and human populations.