Plant control of hydrological cycle in the vegetation season
Abstract
Long-term observations of water regime of soils in headwater regions show that transpiration serves to cool vegetation down so as it temperature not to exceed the optimum value of 24-25 °C. It is shown that optimum temperature of vegetation is the crucial factor in the natural selection controlling species mix of climax and near-natural vegetation. It could be deduced that extremalization of hydrological cycle is caused by vegetation cover change in a large areal scale. Conclusions were obtained by an interpretation of monitoring and simulation of hydrological cycle in submontane and mountain locations in the Czech Republic at altitude 600-1400 m a.s.l. with grass, dwarf pine forest and spruce vegetation: (1) Vegetation with optimum temperature of 25 °C is most able to live in those conditions. In the seasons poor in precipitation, the phytomass production decrease in 6 % can be expected in comparison with the average seasons. (2) Vegetation with lower optimum temperature then 24 °C could be the cause of undesired increase in transpiration at the expense of outflow, and vegetation decease due to long-term lack of soil water in dry seasons. (3) Vegetation with optimum temperature higher than 25 °C could be the cause of the transpiration decrease resulting in the runoff- and local air temperature increase. Support from the Grant Agency of ASCR (Grants No. A30060001 and S2060104) and Ministry of Environment of the Czech Republic (Project No. VaV 610/3/00) is greatly acknowledged. Keywords: Hydrological cycle; plant transpiration; natural selection hypothesis.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA.....5952M