Cite as:
Wittich, B.; Horna, V.; Homeier, J. &amp; Leuschner, C. (2012): <b>Altitudinal decrease in photosynthetic capacity in tropical trees: A case study from Ecuador and a pantropical literature analysis</b>. <i>Ecosystems</i> <b>15</b>, 958-973.

Resource Description

Title: Altitudinal decrease in photosynthetic capacity in tropical trees: A case study from Ecuador and a pantropical literature analysis
FOR816dw ID: 1116
Publication Date: 2012-08-15
License and Usage Rights:
Resource Owner(s):
Individual: Bärbel Wittich
Individual: Viviana Horna
Individual: Jürgen Homeier
Individual: Christoph Leuschner
In tropical mountains, trees are the dominant life<br/> form from sea level to above 4,000-m altitude under<br/> highly variable thermal conditions (range of<br/> mean annual temperatures: <8 to >28C). How<br/> light-saturated net photosynthesis of tropical trees<br/> adapts to variation in temperature, atmospheric<br/> CO2 concentration, and further environmental<br/> factors, that change along elevation gradients,<br/> is not precisely known. With gas exchange<br/> measurements in mature trees, we determined<br/> light-saturated net photosynthesis at ambient<br/> temperature (T) and [CO2] (Asat) of 40 tree species<br/> from 21 families in tropical mountain forests at<br/> 1000-, 2000-, and 3000-m elevation in southern<br/> Ecuador. We tested the hypothesis that stand-level<br/> averages of Asat and leaf dark respiration (RD) per<br/> leaf area remain constant with elevation. Standlevel<br/> means of Asat were 8.8, 11.3, and 7.2 lmol<br/> CO2 m-2 s-1; those of RD 0.8, 0.6, and 0.7 lmol<br/> CO2 m-2 s-1 at 1000-, 2000-, and 3000-m elevation,<br/> respectively, with no significant altitudinal<br/> trend. We obtained coefficients of among-species<br/> variation in Asat and RD of 20?53% (n = 10?16 tree<br/> species per stand). Examining our data in the<br/> context of a pan-tropical Asat data base for mature<br/> tropical trees (c. 170 species from 18 sites at variable<br/> elevation) revealed that area-based Asat<br/> decreases in tropical mountains by, on average,<br/> 1.3 lmol CO2 m-2 s-1 per km altitude increase (or<br/> by 0.2 lmol CO2 m-2 s-1 per K temperature<br/> decrease). The Asat decrease occurred despite an<br/> increase in leaf mass per area with altitude. Local<br/> geological and soil fertility conditions and related<br/> foliar N and P concentrations considerably influenced<br/> the altitudinal Asat patterns. We conclude<br/> that elevation is an important influencing factor of<br/> the photosynthetic activity of tropical trees. Lowered<br/> Asat together with a reduced stand leaf area<br/> decrease canopy C gain with elevation in tropical<br/> mountains.
| altitudinal gradient | foliar N | foliar P | leaf dark respiration | light-saturated net photosynthesis | tropical lowland forests | mature trees | C source limitation | tropical montane forest |
Literature type specific fields:
Journal: Ecosystems
Volume: 15
Page Range: 958-973
Metadata Provider:
Individual: Jürgen Homeier
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