Double Effects of Age and Environment on Resource Allocation Trade-offs of Salix psammophila in Different Microtopographic Habitats of a Sand Dune

Abstract

Adjustments to the allocation of aboveground biomass allocation are an important component of the adaptive strategies of plant growth. Plants can modify their biomass allocation patterns to adapt to various environmental conditions. Sandy areas vary widely in topography, generating a diversity of microenvironments. However, knowledge about biomass allocation patterns of shrubs in different microtopographic areas in sandy habitats remains limited. Moreover, most studies have not considered the effect of age on plant biomass allocation responses to habitat differences. In August 2017, we measured the age, height, ground-level diameter, and leaf and stem matter of Salix psammophila, a species that overwhelmingly dominates a wide range of habitats in China. Biomass allocation patterns (leaf vs. stem biomass, biomass vs. diameter) were compared between two sandy vegetation environments in an area of the Mu Us Sandy Land. The results indicated that the rate of biomass accumulation decreased with age and, as shoots aged, they tended to allocate more biomass to stems, which provide support and transport functions, than to leaves (assimilatory organs). Soil moisture was the main environmental factor influencing the allocation strategy of S. psammophila. Favorable moisture habitats increased the overall biomass accumulation rate by promoting the allocation of biomass to leaf tissue. Habitat and age had an interactive effect on biomass accumulation and allocation, and larger plants were more likely to suffer from resource limitation. This study contributes to a better understanding of the life-history strategies of shrubs under frequently changing sandy conditions, which can contribute to efforts in vegetation recovery management.