|Scientific Name:||Pinus longaeva|
|Taxonomic Notes:||In some references it has been treated as a variety of Pinus aristata (Pinus aristata Engelm. var. longaeva (D.K. Bailey) Little).|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor/s:||Stritch, L., Mahalovich, M. & Nelson, K.G.|
|Reviewer/s:||Thomas, P. & Farjon, A.|
Currently there are no known subpopulations where the Great Basin Bristlecone Pine (Pinus longaeva) numbers are decreasing. Throughout its range subpopulations are either increasing or remaining stable. Projection of population trends due to climate change are unknown and would be speculative at best. At most occurrences there is additional elevation to allow for subpopulations of P. longaeva to move up slope. To date white pine blister rust is not adversely affecting Great Basin Bristlecone Pine populations. On this basis we have assessed this species as Least Concern.
|Range Description:||Widely scattered in high mountains near timberline, from the White and Inyo Mountains of eastern California, east through eastern California and southwestern and eastern Nevada, to central Utah. The species occurs on USDA National Forest System lands, USDI Bureau of Land Management (BLM) and National Park Service lands, and Nevada Department of Wildlife lands.
Great Basin Bristlecone Pine occurs in several USDA Forest Service Research Natural Areas (RNAs). RNAs are designated areas that include high quality ecosystems in natural condition, unique ecosystems and ecological features, and plants of special concern. The management emphasis of these areas is on maintaining natural processes. In the Nevada Humboldt-Toiyabe NF, Intermountain Region it is reported from Carpenter Canyon (1,622 ha), Mt Moriah Table (355 ha), Pearl Peak (269 ha), Troy Peak (1,012 ha) and White Pine Creek (319 ha). In the Utah Dixie NF, Intermountain Region it is recorded from Red Canyon (186 ha), Table Cliff (526 ha). In the California Inyo NF, Pacific Southwest Region it is recorded from McAfee (822 ha), Whippoorwill Flat (711 ha) and White Mountain (932 ha).
In addition to Forest Service RNAs, Great Basin Bristlecone Pine occurs within several other areas with a management emphasis on conserving important ecological features. The Ancient Bristlecone Pine Forest Botanical Special Interest Area (Ancient Bristlecone Pine Forest)(11,732 hectares, established 1958) on the Inyo National Forest in California is managed to protect the Bristlecone Pines for public enjoyment and scientific study. Reported National Park System locations include Death Valley (CA), Great Basin (NV), Bryce Canyon (UT), and Zion (UT) National Parks, and Cedar Breaks National Monument (UT). BLM locations include Amphitheater Natural Area No. 285 (UT), and Heusser Mountain Bristlecone Pine Natural Area No. 72 (UT). Great Basin Bristlecone Pine is also reported from the Hayford Peak Natural Area No. 71, within the Desert National Wildlife Refuge, managed by the Nevada Department of Wildlife. Additional locations exist throughout the broader range described above (eastern California to central Utah).
Native:United States (California, Nevada, Utah)
|Range Map:||Click here to open the map viewer and explore range.|
Quantitative information on population sizes is absent or sparse in this high elevation, non-commercial tree species. Utilizing the Research Natural Areas and Ancient Bristlecone Pine Forest acreages listed in 4b, a rough estimate of the size of individual subpopulations may range from 186 to 11,732 ha. Studies conducted in the mid-1980s concluded that subpopulations at Cedar Breaks (UT) and in the Egan Range were increasing, while the Wheeler Peak (NV) subpopulation was stable. In the White Mountains (CA) seedlings are establishing beyond the current upper elevational limits of mature trees, and no die-off is currently being observed at lower elevations, potentially indicating a continuing expansion of their range. Seedling establishment appears to be at a rate sufficient to replace current mortality.
Though generally restricted to high elevation mountain tops in the Great Basin, on isolated mountain ranges separated by xeric valleys, genetic diversity (He) is moderate to very high (0.134 to 0.327) particularly in Nevada, with little population differentiation (Fst or Gst ranging from 0.011 to 0.169) and low inbreeding coefficients (F ranging from 0.078 to 0.103). Populations in the White Mountains may be less genetically diverse than eastern populations, showing slightly lower than average genetic variation compared to most pine species.Great Basin Bristlecone Pine is well-known for slow growth rates and extreme longevity approaching 5,000 years. The Ancient Bristlecone Pine Forest contains trees as old as 4,600 years, as well as logs more than 4,000 years older and is a noted area for dendrochronology and paleoclimatic work relating to fossil timberlines. Another grove of ancient age is in Wheeler Peak Scenic Area, Humboldt-Toiyabe National Forest (NF), Nevada.
|Habitat and Ecology:||
Great Basin BristleconePpine occurs in montane, subalpine, and timberline communities. It occurs in pure stands, but is also frequently codominant with Limber Pine (Pinus flexilis). Other associated species, depending on geographic location and site characteristics, include Single Leaf Pinyon (Pinus monophylla) at lower elevations, Quaking Aspen (Populus tremuloides) on mesic sites, and Engelmann Spruce (Picea engelmannii), Subalpine Fir (Abies lasiocarpa), Rocky Mountain White Fir (Abies concolor var. concolor), and Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca) in eastern Nevada and Utah.
The understorey in Great Basin bristlecone pine communities is typically sparse. Shrub associates include Big Sagebrush (Artemisia tridentata), Low Sagebrush (Artemisia arbuscula), Wax Currant (Ribes cereum), Curl-leaf Mountain Mahogany (Cercocarpus ledifolius) and others. Common associated herbaceous species include Prairie Junegrass (Koeleria macrantha), Bottlebrush Squirreltail (Elymus elymoides), King’s Sandwort (Arenaria kingii), and Granite Prickly Phlox (Leptodactylon pungens). In general, stands become increasingly diverse eastward through the range of the species, with a corresponding decrease in altitudinal range. Overall, plant diversity in these Bristlecone Pine communities is greater on limestone-derived soils than on quartzite-derived soils.
Great Basin Bristlecone Pine has the longest life span of any nonclonal species in the world. It is believed that the longevity of Bristlecone Pines is directly related to site adversity, with a high proportion of dead: live wood reducing respiration and water loss, thereby extending the life span of the tree. A relationship between tree age and proportion of dead stemwood suggests that the great ages of some individuals are related to their capacity to survive partial die-back while maintaining a constant ratio of photosynthesizing and non-photosynthesizing live tissue. In addition, high-elevation, arid environments are poor habitats for insects and root-decaying fungi that might otherwise reduce the life span of these ancient trees.
Great Basin Bristlecone Pine communities are highly drought-tolerant, generally found on very dry, mid- to high-elevation exposed slopes and ridges, with no evidence of Pleistocene glaciation. Slopes are typically steep, ranging from 10% to 50%. Stands are typically very open at high elevations, with a sparse understory. At lower elevations, Great Basin Bristlecone Pine is generally found in denser, mixed forests. Great Basin Bristlecone Pine is shade intolerant and cannot establish in very dense forest environments. Canopy cover may range from approximately 15-50%, with more open stands on harsher higher elevation sites containing massive multi-trunked trees, and tall upright trees with more tapered single trunks characterizing lower elevation sites with higher canopy density.
Soils are shallow lithosols, usually derived from limestone or dolomite, though occasionally sandstone or quartzite soils support Great Basin Bristlecone Pine. Great Basin Bristlecone Pine is found in arid climates with cold winters and droughty summers. Annual precipitation ranges from 300-600 mm, with temperatures as low as -18°C in January to 34°C in July.
Climate change: The effects of current and future climatic conditions on Great Basin Bristlecone Pine regeneration are uncertain. Climate change may be hindering regeneration on sites in the interior Great Basin.
The best development of Great Basin Bristlecone Pine forests occurred during the Pleistocene, when the climate was both cooler and wetter. Extensive forests extended down mountain slopes in the Great Basin, and Great Basin Bristlecone Pines occupied Mojave Basin mountain slopes, where they are now absent.
Mountain top stands, lower elevation stands, or stands now on marginal sites may be threatened by climate change, though it is difficult to predict the complex interactions of changes in temperature, precipitation patterns, and shifting insect and disease ranges. In many places, potential habitat occurs upslope of existing populations, indicating potential for upslope shifts in distribution to accommodate a warming climate. Lower elevation populations could potentially be compromised by black stain, introduced by upslope movement of pinyon pine. Shifting patterns of various insects and diseases in response to long term changes in temperature and/or precipitation could affect existing stands, particularly at the current lower tree limit.
Blister rust: Bristlecone Pine is one of the five-needle pines susceptible to the exotic pathogen, White Pine Blister Rust (Cronartium ribicola A. Dietr.). Blister rust resistance is being evaluated at the USDA Forest Service, Institute of Forest Genetics, Placerville, CA. Preliminary results show no evidence of the hypersensitive response with 30% of the seedlings canker-free. Both Rocky Mountain Bristlecone Pine (Pinus aristata Engelm.) and Great Basin Bristlecone Pine are highly resistant to blister rust, in part due to wax-occluded stomata. In addition, the predominant alternate host, Ribes cereum, is highly resistant to infection by aeciospores, thereby making it difficult for the rust to complete its life cycle in the alternate host. However, levels of resistance of Great Basin Bristlecone Pine to blister rust remain unclear. Laboratory studies have shown Great Basin Bristlecone Pine seedlings to be lacking key alleles that confer genetic resistance to blister rust. Populations in the White and Inyo Mountains, which lie close to moderately high infection centres in the Sierra Nevada, may be at greatest risk for blister rust infection and spread.
Other insects and/or disease agents: Mountain pine beetle, dwarf mistletoe, wood-rot basidiomycetes and wood decay fungi are all known to infest Great Basin Bristlecone Pine. The dry high-elevation sites of most Great Basin Bristlecone Pine currently serve to slow fungal growth and wood decay.
Wildland fire: based on its thin bark, Great Basin Bristlecone Pine is adapted to survive only low-severity surface fires. With low productivity and widely spaced stands, there are usually not enough fuels to carry fire in high-elevation Great Basin Bristlecone Pine sites. When fires do occur at high elevations, they are typically small, low-severity surface fires. Stand dynamics in these areas are generally more influenced by climate and seed dispersal patterns than by fire.
In contrast, fuels are sufficient to carry fire in denser, lower-elevation sites where Bristlecone Pine occurs in mixed forests. Little documentation exists of post-fire establishment, growth rate, and successional role of this species. Post-fire establishment may be favoured on mixed conifer ecotones, lower-elevation limestone soils, and other sites that are marginally productive for other conifer species but relatively good for Great Basin Bristlecone Pine. Further research is needed on this topic.Commercial timber production: Though Great Basin Bristlecone Pine-limber pine forests were logged in the 1860s for structural timber, the species is no longer commercially important as a timber product.
USA National and State Listing:
The California Natural Diversity Database (CNDDB) maintains global and state rankings for species of concern. Great Basin Bristlecone Pine has a global rank of G4, meaning it is apparently secure, but there may be some cause for concern, and a state rank of S3.3, meaning it is vulnerable (few populations, and/or small population size) in California, with no known current threats. The California Native Plant Society includes it on their List 4.3, meaning it is uncommon in California, but not very endangered. The vast majority of stands and subpopulations are within protected areas, some of which were specifically designated to protect this species. Active monitoring programmes are also in place. Ex situ gene conservation including seed and pollen in cold storage, and clone banks has been initiated.
Conservation Actions and Research Needed:
Further research is needed on the potential effects of climate change on the existing distribution of Great Basin Bristlecone Pine, including insect and disease dynamics, and fire dynamics in the denser mixed forests. Active fire management may be needed in some stands.
Identification, harnessing and deploying (tree planting) rust resistant Great Basin Bristlecone Pine may need to be considered, particularly in areas where regeneration is absent among persistent standing dead stems and no local seed source is available for natural regeneration. In these cases, special attention should be paid to maintaining the genetic integrity of individual stands, as appropriate.
Identification of new Research Natural Areas in California, Nevada and Utah may provide protection for additional populations, depending on the current management status of those lands. Other protected areas include designated wilderness.
|Citation:||Stritch, L., Mahalovich, M. & Nelson, K.G. 2011. Pinus longaeva. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 13 December 2013.|
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