|Scientific Name:||Sequoiadendron giganteum|
|Species Authority:||(Lindl.) J.T.Buchholz|
Wellingtonia gigantea Lindl.
|Taxonomic Notes:||This species was formerly included under the family Taxodiaceae. That family is now merged with Cupressaceae (see Farjon 2005).|
|Red List Category & Criteria:||Endangered B2ab(ii,iii,v) ver 3.1|
|Assessor/s:||Schmid, R. & Farjon, A.|
|Reviewer/s:||Thomas, P. & Stritch, L.|
Despite the fact that almost all existing ‘groves’ of Sequoiadendron giganteum are in protected areas and some have been protected for more than a century, the population is in continuous decline. The actual area of occupancy, estimated to be 142 km2, falls well below the threshold for Endangered (500 km²) and with a continuing decline due to inadequate regeneration and natural death of (over)mature trees, which are being replaced by other, competing conifers, the B2 criterion applies and the species meets the criteria for listing as Endangered.
|Range Description:||Endemic to the USA: California, Sierra Nevada (Calaveras, Fresno, Madera, Mariposa, Placer, Tulare & Tuolumne Counties). It is known to occur in ca. 67 groves which stretch over a length of ca. 400 km along the western slopes of the Sierra Nevada in a belt at most 25 km wide (severely fragmented), covering a total area of occupancy of ca. 14,200 ha. Most of the groves (59) are in the two southernmost counties: Fresno and Tulare.|
Native:United States (California)
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The present trend in recruitment of Sequoiadendron giganteum is downwards, due to competition in the absence of periodic fires in many of the protected groves. This leads over time to a downward trend in the number of mature individuals in the population. There is at present insufficient regeneration to maintain Sequoia populations in these groves (Stephenson in Aune1992, Stephenson 1996).|
|Habitat and Ecology:||This species is forming 'groves' of a few to over 20,000 individuals in the Mixed Conifer Forest belt on the western slopes of the Sierra Nevada. It is mixed with other conifers: Abies concolor, A. magnifica, Calocedrus decurrens, Pinus lambertiana, P. ponderosa, P. jeffreyi, Pseudotsuga menziesii, Taxus brevifolia, and with fewer broad-leaved trees: Quercus kelloggii, Q. chrysolepis, Cornus nuttallii, Alnus rhombifolia, Salix scoulerana, Acer macrophyllum, and shrubs: Castanopsis sempervirens, Ceanothus cordulatus, C. parvifolius, C. integerrimus, Arctostaphylos patula, etc. The relatively narrow altitudinal belt, (830-)1,400-2,150(-2,700) m a.s.l., and the scattered concentration of groves, which tend to become smaller and further apart going north, indicate rather narrow climatic and soil conditions that are optimal in its natural habitat. Most groves are on granite-based residual and alluvial soils, some on glacial outwash, and mildly acidic; best growth is on deep, well-drained sandy loams with available ground water, the latter appears to be an important limiting factor. The climate is humid, with mostly autumn rain and winter snow, and dry summers, with mean annual precipitation between 900-1,400 mm, but with high year-to-year variation. Temperature in winter is mild, with light frosts but occasional extremes, and warm, occasionally hot, in summer. Sequoiadendron giganteum is well adapted to low-intensity forest fires (extremely thick bark) and resists windfall exceptionally well; its wood is also rot-resistant. As a result its longevity ranges from 2,000-3,000(-3,200) years.|
|Major Threat(s):||Although nearly all groves (or 92% of the area of occupancy) are on public land, enjoying various levels of protection, the species was previously listed as Vulnerable primarily because of historic rates of decline caused by exploitation. Present problems include fire risks, largely due to (past) management practices which tended to benefit its coniferous competitors (especially Abies) rather than the target species, and which have greatly accumulated the fuel load for future fires to burn more devastatingly (Elliott-Fisk et al.1997). Crown fires could easily spread from adjacent stands of other conifers. Genetic integrity of the small northernmost (and isolated) grove in Placer County is jeopardized by nearby plantings of S. giganteum from other sources (Elliott-Fisk et al. 1997).|
|Conservation Actions:||Nearly all know ‘groves’ of this species are in protected areas; many are within famous national parks or within wilderness reserves of National Forests. There is a considerable literature on the conservation aspects of this species; for compilations see Aune (1994) and Stephenson (1996). The main conservation issue is the long absence of naturally occurring fires in the protected areas where many of the groves of Giant Sequoia occur. Different approaches to solve this problem, from controlled burning to selective logging, have been applied on different lands (burning in national parks, logging in national forests), but so far on too limited a scale to reverse the downward trend in recruitment necessary to maintain the population in the long term. More drastic measures seem to be needed, but are difficult to safely apply and/or are controversial (Elliott-Fisk et al. 1997).|
Aune, P.S. 1994. Proceedings of the symposium on Giant Sequoias: their place in the ecosystem and society, June 23-25, 1992. Gen. Tech. Report PSW-GTR-151. USDA Forest Service , Visalia, California.
Burns, R.M. and Honkala, B.H. 1990. Silvics of North America. USDA, Forest Service, Washington, DC.
Elliott-Fisk, D.L., Stephens, S.L., Aubert, J.E., Murphy, D. and Schaber, J. 1997. Mediated Settlement Agreement for Sequoia National Forest, Section B. Giant Sequoia Groves: an evaluation. Pp. 277-328 in SNEP Science Team and special consultants, Sierra Nevada Ecosystem Project: Final report to Congress: status of the Sierra Nevada. Wildland Resources Center report, no. 40. Centers for Water and Wildland Resources, University of California, Davis.
Farjon, A. 2005. A Monograph of Cupressaceae and Sciadopitys. The Royal Botanic Gardens, Kew.
Farjon, A. 2010. Conifer Database (June 2008) In Species 2000 & ITIS Catalogue of Life: 2010 Annual Checklist (Bisby F.A., Roskov Y.R., Orrell T.M., Nicolson D., Paglinawan L.E., Bailly N., Kirk P.M., Bourgoin T., Baillargeon G., eds). Reading, UK. Available at: http://www.catalogueoflife.org/.
Farjon, A. 2010. A Handbook of the World's Conifers. Koninklijke Brill, Leiden.
Hartesveldt, R.J., Harvey, H.T., Shellhammer, H.S. and Stecker, R.E. 1975. The Giant Sequoia of the Sierra Nevada. U.S. Dept. of the Interior, National Park Service, Washington, D.C.
IUCN. 2013. IUCN Red List of Threatened Species (ver. 2013.1). Available at: http://www.iucnredlist.org. (Accessed: 12 June 2013).
Stephenson, N.L. 1996. Giant sequoia management issues: protection, restoration, and conservation. SNEP Science Team and special consultants, Sierra Nevada Ecosystem Project: Final report to Congress: Status of the Sierra Nevada. Vol. 2. Assessments and scientific basis for management options. Centers for Water and Wildland Resources, University of California, Davis (series: Wildland Resources Center report, no. 37, pp. 1431-1467. Centers for Water and Wildland Resources, University of California, Davis (series: Wildland Resources Center report.
Willard, D. 2000. A guide to the sequoia groves of California. Yosemite Association, Yosemite National Park.
|Citation:||Schmid, R. & Farjon, A. 2013. Sequoiadendron giganteum. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 21 April 2014.|