Read the passage given below and then answer the questions given below the passage. Some words may be highlighted for your attention. Read carefully. Forests are feeling the heat. In places like the American West, rising temperatures and drought mean less water for trees, sometimes shriveling swath
Read the passage given below and then answer the questions given below the passage. Some words may be highlighted for your attention. Read carefully.
Forests are feeling the heat. In places like the American West, rising temperatures and drought mean less water for trees, sometimes shriveling swaths of woodland. Now, scientists have found that thinning early in forest growth creates tougher trees that can endure climate change. What’s more, these thinned forests can suck carbon out of the air just as fast as dense forests. As trees grow, they convert carbon dioxide into food and store it in their leaves, trunks, and roots. But if trees get too crowded, they compete for light and water—and stressed trees are more susceptible to drought and insect attacks. Removing some trees can ease the competition, letting the remaining trees grow big and healthy. But scientists worry that removing trees can reduce forest carbon storage. These worries, however, are based mostly on models and short-term studies.
To see if the climate trade-off truly exists, scientists tapped into a long-term experiment in northwestern Montana. The forest was broken up into plots. In some plots, the 8-year-old trees were thinned from tens of thousands per hectare down to 494 per hectare (2.5 acres). These trees grew thick trunks and broad canopies. Other plots were left alone, and the teeming trees grew tall and skinny as they competed for sunlight. The scientists at the University of Montana sprouted a new question: How did tree density affect carbon storage?
To find out, they measured tree height, diameter, and width of branches to estimate the amount of carbon stored. They also calculated the carbon contained in other plants, dead wood, and forest floor debris. Total carbon was nearly the same in both forests. The un-thinned forest had more trees, but the thinned forest compensated with bigger trees. The key is early thinning, before trees start to fight over water and light. The remaining trees grow rapidly. Thinning treatments on mature trees haven’t had such success, because the leftover trees were already weakened by competition.
Which of the following is one of the concerns of the scientists according to the passage?
1). The thinned forests will look unaesthetic to the residents nearby
2). The carbon contained in the trees cannot be measured precisely
3). Removal of trees can reduce the forest carbon storage
4). The un-thinned forests will store more carbon as compared to that stored by thinned forests
1 answers
The line ‘But scientists worry that removing trees can reduce forest carbon storage’ towards the end of the first paragraph suggests that option 3 is one of the concerns of the scientists discussed in the passage. Options 1 and 2 have not been mentioned in the passage and thus can be eliminated.
Option 4 is, in fact, is contrary to the result of the experiment conducted by the scientists. The third paragraph clearly tells us that the total carbon stored in un-thinned and thinned forests was nearly the same.
Thus, option 4 can also be eliminated.