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Titolo:
Water use by whitebark pine and subalpine fir: potential consequences of fire exclusion in the northern Rocky Mountains
Autore:
Sala, A; Carey, EV; Keane, RE; Callaway, RM;
Indirizzi:
Univ Montana, Div Biol Sci, Missoula, MT 59812 USA Univ Montana Missoula MT USA 59812 , Div Biol Sci, Missoula, MT 59812 USA USDA, Forest Serv, Rocky Mt Res Stn, Intermt Fire Sci Lab, Missoula, MT 59807 USA USDA Missoula MT USA 59807 , Intermt Fire Sci Lab, Missoula, MT 59807 USA
Titolo Testata:
TREE PHYSIOLOGY
fascicolo: 11, volume: 21, anno: 2001,
pagine: 717 - 725
SICI:
0829-318X(200107)21:11<717:WUBWPA>2.0.ZU;2-C
Fonte:
ISI
Lingua:
ENG
Soggetto:
HEAT-PULSE METHOD; SAP FLOW; HYDRAULIC CONDUCTANCE; XYLEM CAVITATION; PONDEROSA PINE; USE EFFICIENCY; SAPWOOD AREA; SCOTS PINE; LEAF-AREA; TREES;
Keywords:
Abies lasiocarpa; biomass allocation; Pinus albicaulis; sap flow; shade tolerance; subalpine conifers; succession; water relations;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Citazioni:
44
Recensione:
Indirizzi per estratti:
Indirizzo: Sala, A Univ Montana, Div Biol Sci, Missoula, MT 59812 USA Univ Montana Missoula MT USA 59812 ol Sci, Missoula, MT 59812 USA
Citazione:
A. Sala et al., "Water use by whitebark pine and subalpine fir: potential consequences of fire exclusion in the northern Rocky Mountains", TREE PHYSL, 21(11), 2001, pp. 717-725

Abstract

In subalpine forests of the northern Rocky Mountains, fire exclusion has contributed to large-scale shifts from early-successional whitebark pine (Pinus albicaulis Engelm.) to late-successional subalpine fir (Abies lasiocarpa (Hook. ) Nutt.), a species assumed to be more shade tolerant than whitebark pine and with leaf to sapwood area ratios (ALAS) over twice as high. Potential consequences of high ALAS for subalpine fir include reduced light availability and, if hydraulic sufficiency is maintained, increased whole-treewater use. We measured instantaneous gas exchange, carbon isotope ratios and sap flow of whitebark pine and subalpine fir trees of different sizes inthe Sapphire Mountains of western Montana to determine: (1) whether species-specific differences in gas exchange are related to their assumed relative shade tolerance and (2) how differences in AL:As affect leaf- and whole-tree water use. Whitebark pine exhibited higher photosynthetic rates (A = 10.9 mu mol m(-2) s(-1) +/- 1.1 SE), transpiration rates (E = 3.8 mmol m(-2) s(-1) +/- 0.7 SE), stomatal conductance (g(s) = 166.4 mmol m(-2) s(-1) +/- 5.3 SE) and carbon isotope ratios (delta C-13 = -25.5 parts per thousand +/- 0.2 SE) than subalpine fir (A = 5.7 mu mol m(-2) s(-1) +/- 0.9 SE; E = 1.4 mmol m(-2) s(-1) +/- 0.3 SE; g(s) = 63.4 mmol m(-2) s(-1) +/- 1.2 SE, delta C-13 = -26.2 parts per thousand +/- 0.2 SE; P < 0.01 in all cases). Because subalpine fir had lower leaf-area-based sap flow than whitebark pine (Q(L) = 0.33 kg m(-2) day(-1) +/- 0.03 SE and 0.76 kg m(-2) day(-1) +/- 0.06 SE, respectively; P < 0.001), the higherA(L):A(S) in subalpine fir did not result in direct proportional increases in whole-tree water use, although large subalpine firs used more water than large whitebark pines. The linear relationships between tree size and daily water use (r(2) = 0.94 and 0.97 for whitebark pine and subalpine fir, respectively) developed at the Sapphire Mountains site were applied to trees of known size classes measured in 12natural subalpine stands in the Bob Marshall Wilderness Complex (western Montana) ranging from 67 to 458 years old. Results indicated that the potential for subalpine forests to lose water by transpiration increases as succession proceeds and subalpine fir recruits into whitebark pine stands.

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Documento generato il 19/09/20 alle ore 18:34:00