Leaf Structure And Nutrient Traits Across Important Garden Plants Under Hilly Red Soil In Mid-subtropical Region

Leaf traits including leaf mass per area (LMA), C, N, P concentrations and their ratios are directly related with many ecological and physical functions, such as plant' C assimilation, nutrient use and energy balance. Additionally, leaf traits are closely related with plant ecological adaption, which is very useful to plant selection, community allocation, and ecological management in urban garden. We selected 16 garden plants to study their soil nutrients, leaf area, leaf mass, leaf C, N, and P concentrations, litterfall nutrient concentrations in Qianhu campus of Nanchang university, which located at suburban of Nanchang city, mid-subtropical hilly red soil region. Therefore, we compared the differences in LMA, leaf nutrient concentrations, plant nutrient resorption among different groups based on plant species, functional grouping, community structure type and campus functional area. Major conclusions as follows:(1) Soil organic C, total N and total P were not significant differences among either among 16 species or among six functional groupings, which showed similar soil nutrient status for all selected plants. However, the concentration of soil NH4+-N, NO3--N, mineral N were influcenced by season, plant species, functional grouping, community type and campus functional area. Thus, soil N supply was interacted by soil and plant.(2) Significant differences in LMA (P<0.05) were found among nine species (Osmanthus fragrans≥Magnolia grandiflora≥Cinnamomum camphora=Michelia figo≥Cercis chinensis= Rhododendron simsii= Prunus persica= Salix babylonica= Liriodendron chinese), three functional grouping (Evergreen broadleaved trees> Shrubs= Hardwoods) and five community types (Tree+herb> Shrub+herb= Tree+shrub> Shrub=Tree), while there was not significant differences among five campus functional areas.(3) The average concentrations of leaf N were significant differences among 16 species and six functional groupings, while no significant differences among five community structure types and five campus functional areas. The average concentrations of leaf P were significant differences among 16 species, six functional groupings and five community types, while no significant differences among five campus functional areas. The average values of leaf C/N were significant differences among 16 species, six functional groupings, five community structure types and five campus functional areas. The average values of leaf N/P were significant differences among 16 species and six functional groupings, while no significant differences among five community types and five campus functional areas. Therefore, leaf nutrient traits were influenced by multiple factors, such as plant genetic characteristics, soil nutrient conditions and ecological factors. Additionally, leaf N and P concentrations would be controlled by different limiting factors.(4) Nutrient resorption proficiencies were influenced by plant species, functional grouping, community structure type, and not related with campus functional area. Nutrient resporption efficiencies were influenced by plant species, functional grouping and campus functional area, and not related with community structure type. Thus, nutrient resorption depended on plant traits themselves.(5) LMA was negative related with leaf N concentrations in spring, summer, autumn, winter and average values, plant N resorption proficiency, leaf p concentrations in spring, summer and average values across four season, plant resorption efficiency, while not related with plant N resorption efficiency, leaf P concentrations in autumn and winter, plant P resorption proficiency. Therefore, we deduced that N was more important limiting factor to plant growth than P, and plants were stronger adaption ability to P than to N.In conclusion, leaf structure and nutrient traits depended on plant genetic characteristics, and the plant mechanisms in ecological adaption to LMA, N and P traits would be asynchronous across their evolution history. We suggested that further basic research focused on leaf traits would provide reliable theories for plant selection, community allocation and ecological management in urban garden construction.