The trade-off between safety and efficiency in hydraulic architecture in 31 woody species in a karst area

Abstract

Karst topography is a special landscape shaped by the dissolution of one or more layers of soluble bedrock, usually carbonate rock such as limestone or dolomite. Due to subterranean drainage, overland flow, extraction of water by plants and evapotranspiration, there may be very limited surface water. The hydraulic architecture that plants use to adapt to karst topography is very interesting, but few systematic reports exist. The karst area in southwestern China is unique when compared with other karst areas at similar latitudes, because of its abundant precipitation, with rainfall concentrated in the growing season. In theory, resistance to water-stress-induced cavitation via air seeding should be accompanied by decreased pore hydraulic conductivity and stem hydraulic conductivity. However, evidence for such trade-offs across species is ambiguous. We measured the hydraulic structure and foliar stable carbon isotope ratios of 31 karst woody plants at three locations in Guizhou Province, China, to evaluate the functional coordination between resistance to cavitation and specific conductivity. We also applied phylogenetically independent contrast (PIC) analysis in situations where the inter-species correlations of functional traits may be biased on the potential similarity of closely related species. The average xylem tension measurement, at which 50% of hydraulic conductivity of the plants was lost (Ψ(50)), was only -1.27 MPa. Stem Ψ(50) was positively associated with specific conductance (K(s)) (P < 0.05) and leaf specific conductance (K(l)) (P < 0.05). However, the PIC correlation for both relationships was not statistically significant. δ(13)C was positively related to K(l) in both the traditional cross-species correlation analysis and the corresponding PIC correlations (P < 0.05). The Huber value (sapwood area:leaf area ratio) was negatively correlated with K(s) in both the traditional cross-species correlation and the corresponding PIC correlations (P < 0.01). The characteristics of hydraulic architecture measured in this study showed that karst plants in China are not highly cavitation-resistant species. This study also supports the idea that there may not be an evolutionary trade-off between resistance to cavitation and specific conductivity in woody plants. Whole-plant hydraulic adjustment may decouple the trade-off relationship between safety and efficiency at the branch level.

Eco-physiological adaptation of dominant tree species at two contrasting karst habitats in southwestern China

“…This implies that in most cases, temporary soil water stress events would not occur during the growth season of this region. The data for leaf δ 13 C value from Yang et al 14 and Fan et al 15 also confirms the above conclusions based on chlorophyll fluorescence analyses. They report that the average leaf δ 13 C values of more than 50 tree species in three karst sites across Guizhou are -27.63% 14 , and -28.14% 15 .…”

“…The data for leaf δ 13 C value from Yang et al 14 and Fan et al 15 also confirms the above conclusions based on chlorophyll fluorescence analyses. They report that the average leaf δ 13 C values of more than 50 tree species in three karst sites across Guizhou are -27.63% 14 , and -28.14% 15 . These values are only higher than the values of the tree species of tropic rain forests in Yunnan Province (e.g.…”

Eco-physiological adaptation of dominant tree species at two contrasting karst habitats in southwestern China

“…Yang et al 14 and Fan et al 15 also confirms the above conclusions based on chlorophyll fluorescence analyses. They report that the average leaf d…”

“…C values of more than 50 tree species in three karst sites across Guizhou are -27.63% 14 , and -28.14% 15 . These values are only higher than the values of the tree species of tropic rain forests in Yunnan Province (e.g.…”

Seasonal variations in leaf δ13C values: implications for different water-use strategies among species growing on continuous dolomite outcrops in subtropical China

“…However, mean leaf d 13 C values of all the six species were more positive than typical subtropical species (between -31.1 and -30.5 %, Qu et al 2001), indicating that they exhibited higher WUE. This difference may result from the low levels of water available in karst landscapes Fan et al 2011); plants growing on the continuous dolomite rock outcrops have to use water more efficient than subtropical species in other regions. Moreover, the annual seasonal drought in the study area should have also contributed to the relatively high (positive) leaf d 13 C values (Peuke et al 2006).…”