Late holocene treeline fluctuations in the southern Sierra Nevada

Conference · Tue Jun 01 04:00:00 EDT 1993 · Bulletin of the Ecological Society of America; (United States)

OSTI ID:5984570

Lloyd, A H; Graumlich, L J ^[1]

---

1. Univ. of Arizona, Tucson (United States)

The well documented importance of temperature as a direct and indirect control over tree growth at upper elevational treelines suggests that treeline and subalpine forests may be particularly sensitive to climate change. Sub-fossil wood preserved above current treeline in the southern Sierra Nevada records the past sensitivity of treeline with a rare degree of spatial and temporal precision. We use dendrochronologic dating of sub-fossil specimens of foxtail pine (Pinus balfouriana Grev. Balf.) beyond current treeline to analyze the movements of treeline over the past 3 millenia. Treeline at our study area is complex, consisting of both an upper and a lower, or inverted, treeline. Periods of treeline expansion consisted of both up- and down-slope movement of forests. Treeline was 50 m to 100 m above upper treeline and 20 m to 30 m below inverted treeline from approximately 100 B.C. to at least A-D. 1050. Outer ring dates indicate that the mortality of adults did not occur as a temporally coincident event, but rather that trees died over a period of several hundred years and were not replaced. The majority of trees show a pattern of extremely suppressed ring growth in the decades prior to their death, indicating that conditions were not favorable to tree growth. The timing of mortality of these sub-fossil trees suggests that this most recent treeline movement did not occur as a result of widespread, coincident mortality of adults, but rather was a result of lack of replacement of extremely old individuals. This interpretation is supported by analysis of age distributions in live stands at current treeline, which suggest that recruitment at treeline is an extremely rare event.

• OSTI ID: 5984570
• Report Number(s): CONF-930798--
• Conference Information: Journal Name: Bulletin of the Ecological Society of America; (United States) Journal Volume: 74:2
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540120* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
560400 -- Other Environmental Pollutant Effects
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BIOLOGICAL EFFECTS
CENOZOIC ERA
CLIMATIC CHANGE
CONIFERS
DEVELOPED COUNTRIES
DISTRIBUTION
FLUCTUATIONS
FORESTS
GEOLOGIC AGES
GROWTH
LEVELS
MOUNTAINS
NEVADA
NORTH AMERICA
PALEOCLIMATOLOGY
PALEONTOLOGY
PINES
PINOPHYTA
PLANT GROWTH
PLANTS
QUATERNARY PERIOD
SPATIAL DISTRIBUTION
TREE RINGS
TREES
USA
VARIATIONS
WOOD