Germination of shrub species from Chinese subtropical forests: implications for restoration.

Incorporating native shrubs into restoration projects can improve biodiversity conservation and enhance the sustainability of ecosystem functions. Shrubs grow under different forest canopy structures, facing varied microclimatic conditions according to the forest type and composition. Currently, a lack of information on propagation from seeds and planting material availability hampers the utilization of shrubs in forest restoration. In the present study, we evaluated the effects of temperature and light on germination of 10 shrub species (Ardisia japonica, Callicarpa cathayana, Callicarpa giraldii var. subcanescens, Deutzia schneideriana, Fraxinus sieboldiana, Hydrangea chinensis, Maesa japonica, Rhododendron simsii, Spiraea japonica var. fortune and Weigela japonica var. sinica) occurring in subtropical forests in China. Seeds of all species had null germination in the coolest thermal regime (5/10°C), while optimal temperature requirements varied from 10/20°C to 25/35°C. Seeds of small-seeded species reached higher germination percentages in the light treatments, while larger seeds were not photoblastic. No relationship was detected between light-germination and seed shape index. Our results may assist in the identification of seed traits and suitable shrub species for restoration in specific forest types, thus aiding native forest recovery of structure and composition. Successful recovery leads to enhanced biodiversity, reestablished microhabitats and ecological interactions in the forest understory.