Jamal and Keisha each earn money by washing cars and mowing lawns. Jamal can mow 4 lawns or wash 8 cars in one day. Keisha can mow 3 lawns or wash 9 cars in one day. They both charge $25 for each lawn and $15 for each car.

The chart shows their production after 3 days.

A 3-column table has 2 rows. The first column has entries Lawns, cars. The second column is labeled Jamal with entries 12, 24. The third column is labeled Keisha with entries 9, 27.

Jamal and Keisha are considering entering into an agreement to trade tasks.

How can specialization of labor benefit Jamal and Keisha? Check all that apply.

Jamal can specialize in washing cars, because he has the comparative advantage.
Keisha can specialize in washing cars, because she has the comparative advantage.
Specialization allows them to collectively mow 3 more lawns and wash 3 more cars every three days.
Specialization allows them to collectively mow 12 more lawns and wash 27 more cars every three days.
Specialization allows them to earn more money.

clearcutting reproduces a new even-aged stand by completely removing the mature stand.

clearcutting as a silvicultural treatment has several characteristics:

it causes a sudden environmental change

it removes the seed source from the regeneration area

the configuration of the clearcut may affect seed dispersal

it begins a new rotation

it will eliminate some pests that require forest cover

overall, it temporarily removes the forest cover, transforming the forest community and environment.

clearcutting followed by artificial (seeded or planted) regeneration has several advantages:

we can avoid delay in restocking the site

we can introduce a selected species, seed source, and genotype

we can control arrangement and spacing

we can achieve uniformity in the new stand

we can overcome the problems associated with securing sufficient natural regeneration.

the shelterwood method involves the removal of most of the mature stand at the end of the rotation, but a portion of the mature stand is left standing.   the shelterwood method serves three basic purposes:

to prepare the stand for production of abundant seed

to modify the environment in a way that promotes germination and survival of the selected species

to build up the amount and size of advance regeneration to ensure the prompt restocking of the new stand following overstory removal.

the shelterwood method involves a sequence of 3 cuttings:

preparatory cuttings: make the seed trees more vigorous and set the stage for regeneration. see our thinning page for more information.

establishment/seed cuttings: open up enough vacant growing space to allow establishment of the new regeneration.

removal cuttings: uncover the new crop to allow it to fill the growing space.

the residual trees in the shelterwood must:

be sturdy and windfirm

be able to survive exposure

flower and reproduce seed

be the best trees of the mature stand

keep in mind that the shelter trees must not occupy the entire site.   a void must be created in order to make room for the new regeneration. the amount of shelter to leave will depend on the following factors:

species characteristics (seeding and shelter requirements)

the number of cuttings in the cutting sequence (1, 2, or 3)

landowner objectives

the size of the area to be regenerated

the final removal harvest level required to be profitable

the shelter must be removed before it impedes the growth of the new stand or threatens its survival.

not  

cuba  

russia  

iraq  

el salvador  

explanation:

known as the land of volcanoes, el salvador has visit seismic tremors and volcanic movement. it is the main nation in central america that does not have a coastline on the caribbean sea. about portion of all salvadorans live in the wide open. they are poor and don't have power or running water in their homes. in 1525, pedro de alvarado, a lieutenant of cortés's, vanquished el salvador. el salvador, with alternate nations of central america, pronounced its freedom from spain on sept. 15, 1821, and was a piece of a league of central american states until the point when that association broke up in 1838.

answer; limbic system;

answer; the intervening variable;