Directions: Use the information provided and your knowledge of Life Science to answer the following questions. Show all work where necessary.
Directions: Use the information provided and your knowledge of Life Science to answer the following questions. Show all work where necessary.
Bark beetles, especially the mountain pine beetle (
Diagram 1.
Source: https://www.animalspot.net/beetle
Historically, cold winter temperatures limited bark beetle survival. Prolonged hard freezes killed overwintering larvae, keeping beetle populations low. Warmer winters now result in much higher overwinter survival rates. In addition, hotter summers speed up beetle development, allowing some populations to complete more life cycles per year. These temperature-driven changes represent clear environmental pressures that influence species numbers over time.
As beetle populations surge, their geographic range has expanded dramatically. The insects have moved northward into British Columbia and the Yukon, and eastward across the Canadian Rockies—territory once too cold to support them. This expansion demonstrates how environmental change can lead directly to increases in the number of individuals of a species and facilitate the establishment of populations in new regions.
These beetle outbreaks have additional ecosystem consequences. As beetles kill large numbers of mature pines, the affected forests shift toward young, early-successional species. Some species highly dependent on old-growth pine forests have declined. In extreme cases, entire stands of lodgepole pine have collapsed, demonstrating how environmental change can contribute to localized extinction or major reductions in certain species.
Diagram 2.
Source: https://www.climatesignals.org/resources/map-bark-beetle-damage-american-west-2000-2014
Multiple lines of evidence support these conclusions. Long-term monitoring shows that beetle populations increased dramatically following periods of unusually warm winters. Tree-ring data reveal abrupt declines in pine growth and sudden mortality events that align with beetle outbreaks. Satellite imagery documents the rapid spread of beetle-affected forests across western Canada and the United States. Ecological models also show that warming temperatures align with observed increases in beetle survival, reproduction, and dispersal.
Table 1.
Year | Mean Temperature Anomaly ( | Infested Forest Area (million ha) |
|---|---|---|
2000 | 0.2 | 1.2 |
2005 | 0.35 | 2.1 |
2010 | 0.45 | 3.8 |
2015 | 0.62 | 5.4 |
2020 | 0.78 | 7.1 |
2025 | 0.95 | 8.9 |
Graph of Information - Figure 1.
Table 2.
Winter Temperature ( | Beetle Survival Rate (%) |
|---|---|
-25 | 5 |
-20 | 18 |
-15 | 42 |
-10 | 73 |
-5 | 90 |
Graph of Information - Figure 2.
Based on Table 1, which statement best describes the relationship between temperature anomaly and the area of infested forest?
Using Table 2, explain how winter temperature affects beetle survival rate. Include at least one specific data point from the table.
Using Figure 1, describe the overall trend in beetle-infested forest area from 2000 to 2025.
Using evidence from the reading, tables, and graphs, construct a complete CER that explains how climate change has contributed to increased bark beetle populations and their expansion into new geographic regions.
Write a Claim that answers the question, provide at least two pieces of Evidence from the sources, and include Reasoning that links the evidence to your claim.
Which ecosystem impact described in the reading provides evidence that environmental change can reduce the abundance of some species?
Using Table 1, calculate the total change (in million hectares) in infested forest area from 2000 to 2025.