B11B

During secondary succession, which of the these best describes why decomposing pioneer plants give way to larger, more complex plant species, such as hardwood trees?

• Increased amounts of sunlight are able to reach the ground while the pioneer species are decomposing

• Increased soil temperatures from decomposing pioneer species help tree seeds germinate more quickly

• Increased amounts of decomposing pioneer species remove nutrients that tree seedlings need to grow and mature

• Increased amounts of soil from decomposing pioneer species allow plants with more extensive root systems to become established.

Tags

NGSS.MS-LS2-4

Grassland ecosystems in Texas have evolved to depend on periodic fires to return nutrients to the soil and encourage plant reproduction. Humans have prevented fires in many of these grassland areas, resulting in plant and animal communities with little diversity. Wildlife biologists often recommend purposefully starting fires called prescribed burns, which are monitored and controlled, in grassland ecosystems every 3 to 4 years. These biologists observe greater diversity in plant and animal life in the years following a prescribed burn.

What natural processes are the biologists attempting to imitate?

• Biomagnification

• Succession

• Population bottleneck

• Species extinction

Tags

NGSS.MS-LS2-4

NGSS.MS-LS2-1

NGSS.MS-LS2-2

NGSS.MS-LS2-5