Question

Trees grow by adding new wood outward from the center. When a tree is cut down, the series of rings in the stump of the tree tells how old the tree is. The light-colored rings represent the wood that grew in the spring and early summer. The dark-colored rings represent the wood that grew in late summer and fall. One light ring and one dark ring together represent one year of the tree's life. The first year of the tree's life is represented by the core of wood at the center of the tree plus the first dark ring.

The image below shows the rings of an oak tree planted in Boston, Massachusetts, in the spring of 1982. The tree was cut down in 2001.

diagram showing tree rings
Image courtesy of EPA
The graph below shows the average daily precipitation in Boston, MA, each year from 1982 to 2001. The year 1982 was the first year of the tree's growth.

graph showing average daily precipitation
Data courtesy of NASA
The oak tree had its largest increase in diameter in its
year. During this year, the average daily rainfall was
. The tree's rate of growth was very small in the tree's fourteenth year, during which average daily rainfall
.

According to the evidence, the amount of rainfall cannot be the only environmental factor that influences a tree's growth because the year with the most rainfall
.

Answer 1

I can’t see the images/graph you mention. Please upload the stump/rings diagram and the precipitation graph (or paste the numeric data) and I’ll fill in the blanks exactly.

Meanwhile, here are clear steps you can use to get the answers yourself:

1. Map ring number to calendar year:
- The first year = 1982 (core + first dark ring). So year N = 1981 + N. (Example: the 14th year = 1982 + 13 = 1995.)

2. Find the year of largest diameter increase:
- On the stump image, identify the thickest pair of light + dark rings (the widest annual ring). Count which year number that is, then convert to the calendar year using step 1.

3. Find the average daily rainfall for that year:
- On the precipitation graph, read the average daily precipitation value for the calendar year found in step 2.

4. Find the tree’s 14th-year growth and rainfall:
- Locate the 14th ring on the stump (year = 1995). Note whether that ring is very narrow (very small growth).
- Read the average daily precipitation for 1995 on the graph.

5. Finish the reasoning sentence:
- If the year with the most rainfall does not correspond to the year with the widest ring, conclude: “the amount of rainfall cannot be the only environmental factor that influences a tree’s growth because the year with the most rainfall did not have the largest increase in diameter.”

If you upload the images or the precipitation values by year, I’ll do these steps and give the exact year numbers and rainfall amounts.