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This indicator characterizes the proportion of the Tahoe Region within the montane zone (below 7,000 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.
Estimated acres of conifer stands dominated by trees greater than 25-inches dbh (“old growth” forest stands) in montane elevation zones in the Tahoe Region. Some forest types remain unclassified resulting in the N/A column.
Data provided by the USDA Forest Service, R5 Remote Sensing Lab. Access detailed datasets on Tahoe Open Data, including, vegetation type summary, vegetation spatial data, and detailed vegetation attributes.
- Status
- Considerably Worse Than Target
- Trend
- Little or No Change
- Confidence
- Moderate
- Late seral growth covers 2.3 percent of the upper montane zone, considerably worse than the standard of 48 percent.
- Attainment of this threshold is expected in the future. In absence of catastrophic wildfire, it is estimated attainment will take about 100 years.
- Catastrophic wildfires pose the greatest threat to the region's forests. For instance, the Caldor Fire of 2021 burned 20 acres of late seral forest at moderate severity and 90 acres at high severity.
Late Seral Forested Areas. (USFS EcObject 2017)
This indicator characterizes the proportion of the Tahoe Region dominated by stands of old growth conifers. Old growth forests are valued because they add to Tahoe’s ecological integrity by providing a greater diversity of life forms, including a variety of unique lichen, fungi, insects, vegetation and wildlife. Old forests tend to be more structurally complex and resilient to natural disturbances (wildfire) than younger forests, due to tree spacing and fire resistance of bark on mature trees, especially pines. This indicator does not measure the relative condition of this vegetation type.
Late seral or old growth forests are generally defined as forests in later stages of development. In
the Sierra Nevada, trees that greater than 150 to 200 years old are generally referred to as old
growth. 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 (Beardsley et al., 1999; Taylor, 2007; Taylor et al., 2014). Historical land uses, such as clear-cut logging in the late 1800s, dramatically reduced the overall extent of old growth forests in the Region (USDA, 2001). Current forest management emphasizes thinning of overstocked conifer stands, which could result in faster growth rates due to less competition for resources. The TRPA Code of Ordinances addresses enhancement and protection of late seral and old growth forests, and provides protection for trees larger than 30-inches dbh in westside forests, and larger than 24-inches dbh in eastside forests, while allowing for appropriate management actions. Changing climate conditions and drought influence growth rates and can increase susceptibility of forest to insect and disease. The Southern Sierra is experiencing a massive die off due to bark beetle. Incidence and outbreak in the Tahoe Region could dramatically alter the conclusions of this evaluation and estimated timelines to attainment.
No related projects or programs defined for this indicator.
- Considerably Worse Than Target. Late seral stands in the Sierra Nevada are generally defined as those being composed of trees that greater than 150 to 200 years old. Because the Region was largely clear-cut during the Comstock era, the estimated attainment date for the old growth threshold standard, absent a catastrophic fire, is between 2055 and 2095.
- Little or No Change. Absent catastrophic event, progress towards the threshold standard attainment follows the pace of tree growth and aging in the Region.
- High. Methods have been updated. Calculated by using the extracted trees and their estimated dbh to assess the central tendency of those diameters within a polygon and is considered more appropriate than arithmetic mean to characterize a group of trees. Compared to the arithmetic mean, QMD assigns greater weight to larger trees and is used to calculate several metrics within this dataset. Further, QMD is the most accurate measurement of this dataset when assessing tree size due to the strengths of the LiDAR dominant tree extraction algorithms.
- Low. Methods and data have changed since the 2015 evaluation. The last two evaluations used the same dataset, the USFS 2017 EcObject dataset.
- Moderate. If one confidence rating is high and the other is low, the overall confidence rating is moderate.
No photos available.
No documents available.
April 2017. EcObject Vegetation Map v2.1 Product Guide. USDA Forest Service, R5 Remote Sensing Lab.