Water flux in boreal forest during two hydrologically contrasting years; species specific regulation of canopy conductance and transpiration

Abstract

-We estimated the reduction of transpiration from drought for tree species in a mixed boreal 60-year-old stand in central Sweden. Actual transpiration was estimated from direct measurements of sap flow rate in Pinus sylvestris and Picea abies trees during two consecutive years with contrasting precipitation. Drought-induced reduction of transpiration (transpiration deficit) was quantified as the difference between the measured sap flow and the transpiration calculated for non-limiting soil water conditions. The drought-free transpiration was estimated on

Environmental and endogenous controls on leaf- and stand-level water conductance in a Scots pine plantation

“…The Bernhofer et al [8] and Granier et al [19] reported a maximum conductance of 12.5 and 13 mm s -1 for a period in May 1992 at Hartheim. Slightly higher maximum conductances of ca 16 mm s -1 were reported by Beadle et al [7] for P. sylvestris growing in Thetford Forest, UK and by Cienciala et al [11 ] [50]. A longer period of adjustment of two hours or more was reported by Ng and Jarvis [38] for P. sylvestris.…”

Response of water use efficiency to summer drought in a boreal Scots pine forest in Finland

“…Soil water deficit can induce a reduction of transpiration (Bréda et al, 1993;Clenciala et al, 1998;Granier et al, 2007;Irvine et al, 1998), and it has been recognized as the main environmental factor limiting plant photosynthesis on the global scale (Nemani et al, 2003). Even though the occurrence of drought is low in northern Europe, the summer of 2006 in Finland was extremely dry and 24.4 % of the 603 forest health observation sites over entire Finland showed drought damage symptoms by visual examination, in comparison to 2-4 % damaged sites in a normal year (Muukkonen et al, 2015).…”

Effects of canopy cover and seasonal reduction in rainfall on leaf phenology and leaf traits of the fern Oleandra pistillaris in a tropical montane forest, Indonesia

“…Such leaf phenology is considered to be adaptive to seasonal reduction in rainfall, because the reduction of transpiring leaf area should decrease the water loss from plants. Many studies also found that trees often shed leaves during the dry season and start new leaf growth after the start of the rainy season (de Bie et al 1998, Harrison et al 2000, Prins 1988, Richards 1996, Tanner 1983 Bréda et al 1995, Cienciala et al 1998. Reich & Borchert (1984) improves the assimilative capacity per unit leaf area (Ellsworth & Reich 1993, Gould 1993, Niinemets et al 1999, Takahashi et al 2005, 2006 For an individual leaf, acclimation to shade can be explained by leaf life span and LMA:…”