Resilience of a heavily logged grove of giant sequoia (Sequoiadendron giganteum) in Kings Canyon National Park, California

The Big Stump Grove of giant sequoia (Sequoiadendron giganteum (Lindl.) Buchholz) was heavily logged between 1883 and 1889 and the stand naturally regenerated from seed following logging. In 1968, as part of a 100% sequoia tree inventory, all living sequoias (n = 3587) and dead trees and stumps (n=588) were measured (diameter at breast height, dbh) and mapped. A comparison of pre- to post-logging (85 years later in 1968) stand characteristics showed the estimated basal area of 56.7 m² ha⁻¹ in the pre-cut 1883 Big Stump Grove was very similar to the population mean basal area of 30 other giant sequoia groves (with more than 30 trees) in Sequoia and Kings Canyon National Parks. Sequoia density in 1968 was 1.5 times higher than the population mean, and over 45% of the basal area had been recovered after only 85 years. Assuming most re-establishment occurred over roughly a 9 year period (1883–1892), the diameter growth rate of trees less than 1.95 m dbh, averaged 6.1–6.8 mm year⁻¹ but greatly varied as the 24 trees in the 1.8 m size class had a mean diameter growth rate of 21–24 mm year⁻¹. Data generated by dividing the grove into 0.25 ha contiguous plots indicated that only about 3.3 ha of the pre-cut 1883 grove did not have sequoia regeneration whereas 16.5 ha of the 1968 grove had sequoia regeneration but no sign of logs or stumps. The proportion of only-regeneration plots was significantly greater (P<0.05) in peripheral areas compared to core areas of the grove. A stage projection model showed that with typical natality, growth, and mortality rates in the current (t=0; 1968) stand, overrepresentation of 0.3–1.2 m dbh trees may produce a bimodal size distribution lasting perhaps 800 years or more into the future. Giant sequoia stand characteristics such as age and size structure are not highly resilient and may take several centuries to approach the ‘domain’ of age or size structure typical of old-growth sequoia forests. Grove boundaries may be less stable following a major disturbance.