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Unger, M.; Homeier, J. &amp; Leuschner, C. (2012): <b>Effects of soil chemistry on tropical forest biomass and productivity at different elevations in the equatorial Andes</b>. <i>Oecologia</i> <b>170</b>, 263-274.

Resource Description

Title: Effects of soil chemistry on tropical forest biomass and productivity at different elevations in the equatorial Andes
FOR816dw ID: 1117
Publication Date: 2012-08-15
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Resource Owner(s):
Individual: Malte Unger
Contact:
Individual: Jürgen Homeier
Contact:
Individual: Christoph Leuschner
Contact:
Abstract:
The dependence of aboveground biomass and<br/> productivity of tropical forests on soil fertility is not fully<br/> understood, since previous studies yielded contrasting<br/> results. Here, we quantify aboveground biomass (AGB)<br/> and stem wood production, and examine the impact of soil<br/> chemistry on these parameters in mature tropical forest<br/> stands of the equatorial Andes in Ecuador. In 80 plots of<br/> 0.04 ha at four elevation levels (500, 1,000, 1,500 and<br/> 2,000 m a.s.l., total sample area = 3.2 ha), we measured ten<br/> important soil chemical parameters, inventoried all trees<br/> ¸10 cm dbh and monitored stem diameter growth with<br/> dendrometer tapes in 32 plots. Top canopy height and stem<br/> density signiWcantly decreased from 500 to 2,000 m, while<br/> tree basal area increased and AGB remained invariant<br/> (344 § 17 Mg DM ha¡1, mean § SE) with elevation. Wood<br/> speciWc gravity (WSG) showed a signiWcant, but small,<br/> decrease. Stem wood production decreased from 4.5 to<br/> 3.2 Mg DM ha¡1 year¡1 along the transect, indicating a<br/> higher biomass turnover at lower elevations. The only soil<br/> variable that covaried with AGB was exchangeable K in the<br/> topsoil. WSG increased with decreases in N mineralisation<br/> rate, soil pH and extractable Ca and P concentrations.<br/> Structural equation modelling (SEM) revealed that nitrogen<br/> availability acts on stem wood production only indirectly<br/> through a negative relation between N mineralisation rate<br/> and WSG, and a positive eVect of a lowered WSG on stem<br/> growth. The SEM analysis showed neither direct nor indirect<br/> eVects of resin-extractable P on wood production, but a<br/> negative P inXuence on AGB. We conclude that nitrogen<br/> availability signiWcantly inXuences productivity in these<br/> Andean forests, but both N and P are aVecting wood production<br/> mainly indirectly through alterations in WSG and<br/> stem density; the growth-promoting eVect of N is apparently<br/> larger than that of P.
Keywords:
| Ecuador | tree growth | soil nutrients | aboveground biomass | wood production |
Literature type specific fields:
ARTICLE
Journal: Oecologia
Volume: 170
Page Range: 263-274
Metadata Provider:
Individual: Jürgen Homeier
Contact:
Online Distribution:
Download File: http://www.lcrs.de/publications.do?citid=1117


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