|Response of littoral vegetation on climate warning in the boreal zone; an experimental simulation|
Kankaala, P.; Ojala, A.; Tulonen, T.; Haapamäki, J.; Arvola, L. (2000). Response of littoral vegetation on climate warning in the boreal zone; an experimental simulation. Aquat. Ecol. 34(4): 433-444
In: Aquatic Ecology. Springer: Dordrecht; London; Boston. ISSN 1386-2588, more
|Authors|| || Top |
- Kankaala, P.
- Ojala, A.
- Tulonen, T.
The impact of climate warming on the littoral zone of a boreal lake ecosystem was studied experimentally for three growing seasons in two artificial ponds (10 x 27 m) and in replicated chamber experiments. One pond was enclosed in a plastic greenhouse and another untreated pond served as a reference system. During the growing seasons temperature in the greenhouse was maintained at levels 2-3 °C higher than ambient with a computer-controlled ventilation system. One growing season prior to initiation of the experiment, a vegetated littoral zone with equal densities of water horsetail (Equisetum fluviatile) was established in both ponds. Although changes occurred in the species dominance (E. fluviatile - Alisma plantago-aquatica - Sparganium erectum spp. microcarpum - Elodea canadensis) within the three years of the study, the emergent macrophytes emerged earlier and grew better in the warmer conditions of the greenhouse pond compared with those in the reference pond. The difference in above-ground biomass throughout the growing seasons was > 2 fold and after three experimental growing seasons the difference in below-ground biomass of macrophytes was 2.5-fold between the ponds. In replicated chamber experiments the biomass growth of E. fluviatile was also significantly higher in a 2-3 °C higher temperature than under ambient conditions. An ecosystem-scale induced change, characterized by a heavy growth of filamentous algae (mainly chlorophytes)was evident in the vegetated littoral zone of the greenhouse pond. A hypothesis that macrophyte rhizomes function as 'phosphorus pumps' from the sediment and thus accelerate eutrophication in a warmer climate should be further studied.