Ecophysiology of Long-Distance Water Transport in Trees

Dordrecht

2014

S. 99-115

Artikel aus einer ZeitschriftUnselbständiges Werk

200191912

We give a short overview over some basics of tree water relations and the likely impact of future climate changes on the functionality of the soil-plantatmosphere continuum. We start with a short account of the biophysics of water transport and explain some methods for determining relevant parameters in the field and in the laboratory. Important results are described next: the variable values of total water potential in crowns, the use of pressure-volume curves established in the lab for a detailed analysis of leaf water relations in the field, parameters indicating water stress, and the stability of water columns in the xylem. A look at the water relations of small plants shows that the numerical values of key parameters in seedlings or herbs are not much different from those in tall trees; this enigma may have to do with evolutionary selection for a cautious use of soil water reserves. There are still a number of weak spots in our understanding of water transport in trees. We have only a very general knowledge of root distribution over the soil layers and of fine root turnover