Reproductive allocation of two dioecious Rhamnus species in temperate forests of Northeast China

Abstract

When a plant increases resource allocation to reproduction from its limited reserves, the allocation to the other functions is reduced. Because of these trade-offs, differences in reproductive allocation are believed to result in relative differences in life history traits. Dioecious plants provide an excellent opportunity for detecting such possible trade-offs in resource allocation. This study aims to present a finding about the gender-based cost of reproductive allocation. The trade-off between reproduction and foliage biomass allocation was examined in Rhamnus davurica and Rhamnus schneideri at different modular levels (shoot/sub-branch, branch, and shrub/tree level). There were no intra-annual trade-offs between reproduction and foliage biomass in either sex of either species at shoot/sub-branch level, branch level and shrub level. Interannual trade-offs were detected in females for both species. Inter-annual trade-offs existed at all three different modular levels in R. schneideri females, while the evidence of inter-annual trade-offs was only detected at branch level in R. davurica females. At the population level, the sex ratio was female-biased in 2010, and it did not significantly deviate from 1:1 in 2011 in R. davurica. However, the sex ratios were significantly female-biased in both 2010 and 2011 in R. schneideri. This study show that the degree of autonomy of the different plant organs influences the trade-offs between reproduction and growth, which suggests a species-and sex-dependent modular autonomy. © SISEF.