Sub-Alpine Zone
This indicator characterizes the proportion of the Tahoe Region within the sub-alpine zone (greater than 8,500 feet in elevation) dominated by stands of old growth conifers. Old growth forests tend to be more structurally and biologically complex and resilient to natural disturbances (such as wildfire) than younger forests, due to tree spacing and fire resistance of bark on mature trees, especially pines. Soil conditions, aspect, hill slope position, drought frequency, direct sunlight, fire suppression, climate patterns, time, and natural disturbance influence the extent and distribution of large-diameter trees. TRPA and Environmental Improvement Program (EIP) partners have adopted several policies, ordinances and implementing programs designed to promote the conservation and protection of old growth forests.
Status
Estimated acres of conifer stands dominated by trees greater than 25-inches dbh (“old growth” forest stands) in Sub-Alpine elevation zones in the Tahoe Region. Some forest types remain unclassified resulting in the N/A column.
Evaluation Map
Late Seral Forested Areas
2019 Evaluation
- Status
- Considerably Worse Than Target
- Trend
- Little or No Change
- Confidence
- Low
Applicable Standard
VP13: 61 percent of the Subalpine zone (greater than 8,500 feet elevation) must be in a late seral or old growth condition. The Subalpine zone will contribute 5 percent (7,600 acres) of forested lands towards VP12.
Key Points
- As a result of Comstock era logging, late seral forest growth covers less than one percent (0.05) of the sub-alpine zone, considerably worse than the standard of 55 percent.
- The majority of the Region's trees were logged in the Comstock era, so that today's forest is largely mid-stage second growth. In absence of catastrophic wildfire, it is estimated that the Region's second growth forest will mature into old growth in about 100 years.
- Consideration should be given to the establishment of alternative criteria to define late seral and old growth forest stands in the subalpine zone. Trees grow very slowly in the subalpine zone, and even an 18 inch dbh tree can be very old (up to 200 years old). Since mature trees in the subalpine zone are often smaller than 24 inches dbh, interpretation of the threshold standard for that zone should be considered to more accurately reflect the mature state of species occurring in that zone.