Implementation (Monitor Only): Suwanee Grove


Field surveys were completed in 2022 and 2023 and found 62.7% mortality of large sequoias within the area of Suwanee Grove that burned at high-severity in the 2021 KNP Complex Wildfire (data from Soderberg and Das 2023). The 2023 survey data from Suwanee Grove also found an estimated mean of 7,803 sequoia seedlings/acre in this area, equating to a 1.0% probability of being equivalent to the second-year seedling densities determined by Stephenson et al. 2024 (Soderberg et al 2024). While the actual seedling regeneration within the proposed action area does not meet the 90% probability of meeting the sequoia seedlings/acre mean second-year seedling density determined by Stephenson et al. 2024, the pattern of tree mortality in Suwanee Grove is not as contiguous as found in other groves—leaving some live patches that the NPS anticipates will contribute to future seed rain and thereby potential regeneration within this portion of the Grove (Soderberg et al 2024). The NPS specifically completed a patch analysis and found less than 10% of the entire grove is outside the likely seed rain zone. "In such cases, regeneration failure should be less likely to lead to permanent loss of grove area, as existing seed trees remain as a source of replenishment after future fires—so long as those fires are in keeping with the heterogeneous, mixed-severity fire regimes within which giant sequoias evolved" (Soderberg et al. 2024, 12). Based on these field surveys and findings—namely, that sufficient large sequoias are still alive and the majority of the grove area is within the seed rain of these remaining live trees, the NPS has determined that Suwanee Grove is at low risk of losing a large portion of the grove due to regeneration failure. Therefore, planting of nursery grown giant sequoia seedlings is not necessary to prevent type conversion and preserve this grove. The purpose and need of the EA can be met without further action.

Field data from 2023 is available at: Soderberg, D.N., and Das, A.J., 2023, Assessment of giant sequoia mortality and regeneration within burned groves in Sequoia and Kings Canyon national parks (ver. 2.0, January 2024): U.S. Geological Survey data release, https://doi.org/10.5066/P96Z1PBK. This data was collected under a field study that was designed and implemented by the National Park Service (NPS), the United States Geological Survey (USGS), United States Forest Service (USFS), and the University of California, Davis. The NPS therefore requests that any use of this data for publication rely on the full data set (i.e., use of a subset of this data is not seen to be appropriate or in keeping with the methods of data collection) and that any user of this data for publication communicate in advance with the scientists who collected the data. The contact information for these scientists can be obtained by emailing SEKI_Superintendent@nps.gov.

Stephenson et al. 2024 and Soderberg et al. 2024 are also available for download below.
 
Document Content:
Soderberg et al 2024.pdf   (7.4 MB, PDF file)
Stephenson et al 2024.pdf   (5.7 MB, PDF file)
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