Differential hydraulic and carbon economic strategies among four oak species

The fluctuations of precipitation will become more erratic and dramatic, threatening the growth and survival of forest species. Plants usually integrate water and carbon management strategies to deal with environmental variations. The hydraulic strategies of woody plants would modify their carbon capture and allocation patterns, thus characterizing divergent strategies in water and carbon use economy could elucidate the differential responses to climate change among closely related species. To decipher possible correlations between functional traits relating to plant hydraulics and carbon economics, we selected four oak species (one native species, Quercus dentata, and three exotic species, Q. rubra, Q. robur, and Q. palustris) growing in an Oak Nursery to explore trait associations in hydraulic and carbon economics, and to contrast strategy variations among four species.

Our results showed a trade-off between leaf gas exchange rate and water use efficiency, where fast gas exchange related to fluctuating water potential. In carbon allocation patterns, higher Huber values could supply sufficient water in leaves, thereby maintaining water potential stable.

Compared to the exotic oaks, Q. dentata adopted a relatively conservative strategy, embodying high water use efficiency, stable water potential, and leaves with smaller but denser stomata. However, Q. rubra was conservative and rapid-responsive, Q. robur was potentially drought-tolerant, and Q. palustris employed a strategy of less drought-resistant but might be more competitive in the face of abundant resources. Integrating these findings into global conservation efforts will lead to the development of adaptive management practices that foster tree species with better adaptation to environmental variations.