Stem hydraulic supply is linked to leaf photosynthetic capacity: evidence from New Caledonian and Tasmanian rainforests

Abstract

A strong relationship between hydraulic supply of water to leaves and maximum photosynthetic capacity was found in a group of seven conifers and 16 angiosperm species, including two vessel-less taxa, from similar rainforest communities in New Caledonia and Tasmania (Australia). Stem hydraulic supply was expressed as the hydraulic conductivity of branches in terms of leaf area supplied (K L ) and leaf photosynthetic capacity was measured as the mean quantum yield of PSII (Ø PSII ) in leaves exposed to full sun, as determined by chlorophyll fluorescence analysis. A single, highly significant linear regression (r 2 = 0·74) described the relationship between hydraulic conductivity and quantum yield in all species. This suggests that the maximum photosynthetic rate of leaves is constrained by their vascular supply. In both rainforest locations, the K L of conifer wood overlapped broadly with that of associated vessel-bearing and vessel-less angiosperms indicating a degree of hydraulic convergence in these forests.

Gas Exchange, Photochemical Efficiency, and Leaf Water Potential in Three Salix Species

“…1D). Similar results have been documented in some woody species in analogous environments (Christiane andLudger 1999, Brodribb andField 2000). In addition, photosynthesis is partly limited by reduced intercellular CO 2 concentration due to stomata closure (Cornic andBriantais 1991, Quick et al 1992).…”

“…For instance, the depression of g s or PS2 photochemical efficiency, by which plants could reduce water transpiration or protect the photosynthetic apparatus from destroying, can result in decrease of net P N (Knapp andSmith 1999, Jiang andZhu 2001). In addition, reduced leaf water status also contributed to the P N decrease (Brodribb and Field 2000). The reduced Ψ l values play a key role in maintaining the plant water status within a security range in order to avoid xylem cavitation (Cochard et al 1996).…”

Photosynthetic physiology of eucalypts along a sub-continental rainfall gradient in northern Australia

“…The nearly constant c i /c a observed in this study resulted at least partly from a correlation between photosynthetic capacity and stomatal conductance. A close coupling between photosynthetic capacity and stomatal conductance has been previously observed in a range of C 3 and C 4 plant species (Brodribb and Feild, 2000;Cernusak and Marshall, 2001;Hubbard et al, 2001;Wong et al, 1978Wong et al, , 1979Wong et al, , 1985. We found three lines of evidence suggesting that photosynthetic capacity in the leaves that we sampled was linked to stomatal conductance.…”

Recent reduction in the frequency of frost accounts for most of the increased growth of a high elevation spruce forest in northwestern China

“…At annual time steps, the model sums monthly changes in tree number, mean diameter, stand basal area, above-ground volume and biomass and updates L. Without knowledge of stand characteristics, we assumed low stocking of 200 trees ha -1 to prevent changes in number associated with self-thinning (Drew and Flewelling 1977), and kept maximum values of L \ 3.0 m 2 m -2 and monthly transpiration \60 mm based on observations by Tian et al (2011). Normally, as trees grow in height, hydraulic limitations are imposed on stomata that reduce the maximum rates of photosynthesis and transpiration (Brodribb and Field 2000;Warren and Adams 2000;Koch et al 2004). …”