Question

analyzing the effects of drought
one example of a natural disturbance is a drought, a period of very low precipitation. during drought cycles, water levels decrease, the land becomes drier, and the risk of wildfires increases. scientists can track drought patterns by studying data from tree - rings. scientists know that the relative width of a ring in a tree trunk is a good indicator of the amount of rainfall the tree received in a given year. as shown in figure 3a, trees produce wider rings in rainy years and narrower rings in dry years. by analyzing data from tree - rings, scientists discovered that the three - year period between 2012 and 2014 produced the worst drought conditions in california in at least 1,200 years.
satellite images are an important tool scientists use to study how conditions and landscapes change over time, including temperatures. have you noticed in figure 3b, using satellite images, the snow coverage on the sierra nevada mountains in a wet year (figure 3b) can be compared to that of a drought year (figure 3c). the mountains had visibly reduced snow in 2015 than they did in 2010. to confirm their hypothesis, scientists again analyzed data from tree - rings. they found that the amount of snow in 2015 was the lowest it had been in 500 years.
explain melted snow from the sierra nevada mountains and other mountain ranges is an important water source for much of california. using evidence, explain why a lack of snow in the mountains could make drought cycles worse over time.
analyze how could scientists use data from tree - rings to learn more about ecosystems in the past? use evidence from the tree - ring in figure 3a to support your answer.

Explanation:

1. Lack of snow worsening drought cycles: Melt - down snow from mountains is a key water source in California. A lack of snow means less water availability during dry seasons. This reduces soil moisture, limits water for plants and human use, and can lead to more severe drought conditions over time as there is less water to replenish water bodies and support ecosystems.
2. Using tree - ring data for past conditions: Tree rings can provide information about past precipitation levels. Wider rings usually indicate wetter years, while narrower ones suggest drier years. Scientists can analyze the width and pattern of tree rings to infer past droughts, their severity, and frequency. For example, if a tree has multiple consecutive narrow rings, it may indicate a long - term drought event in the past.

Answer:

1. A lack of snow in the mountains could make drought cycles worse over time because snowmelt is an important water source. Without enough snow, there is less water to replenish water supplies during dry periods, leading to more severe drought conditions.
2. Scientists can use tree - ring data to learn about past conditions as the width of tree rings reflects past precipitation. Narrow rings may indicate drought years and by analyzing the pattern of rings, they can understand past drought severity and frequency.