Unger, M.; Homeier, J. & 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
License and Usage Rights:
Resource Owner(s):
Individual:
Malte Unger
Contact:
email:
munger1 <at> gwdg.de
Germany
Individual:
Jürgen Homeier
Contact:
email:
jhomeie <at> gwdg.de
Faculty of Resource Management
University of Applied Sciences and Arts (HAWK)
37077 Göttingen
Germany
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:
email:
jhomeie <at> gwdg.de
Faculty of Resource Management
University of Applied Sciences and Arts (HAWK)
37077 Göttingen
Germany
