Nutrient-acquisition strategy influences seed nutrient concentration and seed-to-seedling transition in ecological restoration in a regional dryland flora

Seed-to-seedling transition is a primary bottleneck in dryland and post-mining ecological restoration. The role of internal seed nutrent characteristics in this critical transition remains poorly understood, despite its possible utility to inform species selection for restoration. Seed mass and nutrient characteristics were determined for 188 sclerophyll shrubland species from semi-arid Western Australia (35 % of regional floristic diversity) to determine the degree to which they were driven by functional traits. Additionally, seeds of 175 species were broadcast among different surface cover treatments in a dryland post-mining ecological restoration trial, to determine whether seed mass, seed nutrient concentration, or functional traits were informative at predicting seed-to-seedling transition. Examined functional traits explained 48 % of variation in seed mass and nutrient characteristics. Greatest effect sizes included embryo type for seed mass, and nutrient-acquisition strategy for the concentration and ratios of nitrogen, phosphorous and potassium. Seed-to-seedling transition was most significantly influenced by functional traits including nutrient-acquisition strategy, embryo type, dispersal syndrome, growth form, and life history, as well as increasing seed potassium concentration which may offer a nutritional advantage for germination and establishment on nutrient-poor substrates. This study helps bridge the science-practice gap in seed-based restoration, laying the foundations for evidence-based approaches to determining most effective use of limited seed resources. Seed- and species-trait filters should be applied when selecting species for restoration seed mixtures, improving cost-efficiency and ethical seed use by omitting species unlikely favoured on a given restoration substrate prior to seeding.