Response of root foraging and morphology to different soil phosphorus forms in a tree diversity pot experiment

Background: Phosphorus (P) is a limiting element for primary productivity in subtropical and tropical regions. The maintenance of soil P availability through species diverse forests might be an important ecosystem service.... [ view full abstract ]

Background: Phosphorus (P) is a limiting element for primary productivity in subtropical and tropical regions. The maintenance of soil P availability through species diverse forests might be an important ecosystem service. Meanwhile, given the large range of biologically available soil P forms, and the variety of mechanisms by which plants can access P, it is assumed that co-existing plant species partition soil P to increase P use efficiency and reduce competition.
Materials and Methods: Four subtropical tree species seedlings, comprising Castanea henryi, Lithocarpus glaber, Quercus fabri and Liquidambar formosana were planted in one pot as monoculture, two-species and four-species-mixtures in different substrates containing equal amount of total P, but different forms of P derived from: a) topsoil with large proportion of organic P; b) subsoil with mostly inorganic P; c) mixed litter with solely organic P; d) mineral inorganic P fertilizer.
Results: The results showed that fine root biomass and productivity were not significantly different among the species diversity level, while the significantly higher fine root biomass were found in the treatment with topsoil, followed by the subsoil and litter, and the treatment with P fertilizer the lowest. While the SRL was the highest in P fertilizer treatment, and lowest in pot with topsoil for all the species, except for L. formosana.
Conclusion: The diversity effects on P partitioning use in this bioassay experiment was not significant, and the seedlings adapted to the different soil P forms by changing either root foraging or morphology, which are essential for P-acquisition.