Strobl, S.; Cueva Ortiz, E.; Silva, B.; Knuesting, J.; Schorch, M.; Scheibe, R.; Bendix, J. & Beck, E. (2017): <b>Water relations and photosynthetic water use efficiency as indicators of slow climate change effects on trees in a tropical mountain forest in South Ecuador</b>. <i>Ecological Indicators </i> <b>83</b>, 550–558.
Resource Description
Title:
Water relations and photosynthetic water use efficiency as indicators of slow climate change effects on trees in a tropical mountain forest in South Ecuador
email:
bendix <at> staff.uni-marburg.de
Deutschhausstraße 12
Room No. 02 A 48
35032 Marburg
Faculty of Geography
Germany
Individual:
Erwin Beck
Contact:
email:
webmaster <at> lcrs.de
Abstract:
The effects of an increasing moisture on trees of the tropical species-rich mountain rain forest in the South<br/>
Ecuadorian Andes was investigated, using the daily total water consumption (TWC) and the instantaneous<br/>
water use ef?ciency (WUE, ratio of photosynthetic CO2 uptake per water loss by transpiration) as eco-<br/>
physiological indicators. Two canopy and one sub-canopy tree species, (Vismia tomentosa, Clusiaceae, an<br/>
as of yet unknown Lauracee, and Spirotheca rosea, Bombacaceae) were the experimental objects. Seasonal<br/>
changes as well as a long-term (18 months) trend of increasing precipitation caused an inverse reaction<br/>
of the TWC of the trees. Because of a rather unlimited water supply to the trees from a permanently high<br/>
water content of the soil, transpiration followed mainly the atmospheric demand of water vapor, and<br/>
increasing moisture hence reduced water loss by transpiration. It was hypothesized that in spite of the<br/>
reduction in transpiratory water loss photosynthetic carbon acquisition would be not or less affected<br/>
due to an increase in water use ef?ciency. Concomitant measurements of photosynthetic net CO2 uptake<br/>
showed the expected increase of WUE in V. tomentosa and S. rosea, but no clear reaction of the Lauracee.<br/>
Accompanying measurements of stem extension growth con?rmed an undiminished growth of V. tomen-<br/>
tosa and S. rosea but showed also suspended growth of the Lauracee during the wettest months. While<br/>
TWC can be continuously monitored with the heat dissipation technique, WUE is determined by leaf<br/>
porometry in campaigns for which access to the canopy is required. Simultaneous recordings of the gas<br/>
exchange of leaves at 4 different positions in the crown of one of the experimental trees (V. tomentosa)<br/>
showed the usability of the trait WUE in combination with the total daily water consumption as indicator<br/>
set for assessing the response of trees to a subtly changing climate. However, not all tree species appear<br/>
as likewise useful indicator trees
Keywords:
| South Ecuador | tree water relations |
Literature type specific fields:
ARTICLE
Journal:
Ecological Indicators
Volume:
83
Page Range:
550–558
Metadata Provider:
Individual:
Jörg Bendix
Contact:
email:
bendix <at> staff.uni-marburg.de
Deutschhausstraße 12
Room No. 02 A 48
35032 Marburg
Faculty of Geography
Germany
