Although the diseases transferred by columbian exchange resulted in a) a contraction of native populations in asia, the primary effect was a population boom. b) an increased population growth in africa, the long-term effect on global population was stable. c) the depopulation of the americas, the overall effect was a decreased population growth worldwide. d) the depopulation of the americas, the overall effect was an increased population growth worldwide.

The answer is D) The depopulation of the Americas, the overall effect was an increased population worldwide

When the Taino gathered on the shores of San Salvador Island to welcome a small party of foreign sailors on 12 October 1492, they had little idea what lay in store. They laid down their weapons willingly and brought the foreign sailors—Christopher Columbus and his crewmen—tokens of friendship: parrots, bits of cotton thread, and other presents. Columbus later wrote that the Taino “remained so much our friends that it was a marvel.”

A year later, Columbus built his first town on the nearby island of Hispaniola, where the Taino numbered at least 60,000 and possibly as many as 8 million, according to some estimates. But by 1548, the Taino population there had plummeted to less than 500. Lacking immunity to Old World pathogens carried by the Spanish, Hispaniola’s indigenous inhabitants fell victim to terrible plagues of smallpox, influenza, and other viruses.

The population of African and Eurasian peoples in the Americas grew steadily, while the indigenous population plummeted. Eurasian diseases such as influenza, bubonic plague and pneumonic plagues, yellow fever, smallpox, and malaria devastated the Native Americans, who did not have immunity to them. Conflict and outright warfare with Western European newcomers and other American tribes further reduced populations and disrupted traditional societies. The extent and causes of the decline have long been a subject of academic debate, along with its characterization as a genocide.[2]

Populations in other parts like in Europe benefited of the products imported by Europeans like corn, potatoes, etc.

d

Explanation:

this is not a question

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.