Sex-specific strategies of nutrient resorption associated with leaf economics in Populus euphratica

There are differences between sexes in physiological and functional traits and possibly in nutrient resorption, particularly in nutrient-poor environments. However, little is known about the extent of nutrient resorption from fine stems and fine roots, and about how nutrient resorption is related to leaf economics in the males and females of dioecious trees. We investigated nutrient resorption of different organs and explored whether nutrient resorption is associated with nutrient conservation traits of leaves (e.g. leaf thickness, leaf mass per area, LMA) in Populus euphratica females and males in four natural forests along the Tarim River, China. Both female and male leaves had the highest N resorption efficiency (NRE), than stems and roots. We found sexual dimorphism in leaf nutrient resorption at Shaya, Luntai and Yuli forest sites, where P. euphratica males had higher leaf NRE than females, whereas females had a higher leaf P resorption efficiency (PRE). Moreover, the different nutrient resorption strategies were related to leaf economics. P. euphratica males possess a conservation strategy with a higher leaf thickness, LMA and leaf vein density, which positively correlated with leaf NRE, while females with higher leaf PRE resorbed disproportionately more P for the reproductive investment. Synthesis. Populus euphratica males possess a conservation strategy with higher leaf NRE, while females have higher leaf PRE for the reproductive investment. Due to spatial sexual segregation across environmental gradients, dioecious plants are especially vulnerable under future climate change. The differences in nutrient uptake and utilization strategies between females and males may result in a situation where one sex is more prone to future climate change than the other one. Such sex-specific nutrient resorption strategies are associated with leaf economics. The present study deepens our understanding of the nutrient balance and adaptation strategies of plants under climate change.