accepted

Effects of ectomycorrhizal fungal identity and diversity on subtropical tree competition

2016-11-03

2016-11-03

Journal of Plant Ecology

2016-11-03

Aims Mycorrhizal fungi can influence plant nutrient uptake and therefore may alter interspecific plant competition. However, the role of ectomycorrhizal (EM) fungi on interspecific plant competition in subtropical forests is poorly understood. In this study, we investigated the effects of EM fungal identity and diversity on the outcome of interspecific competition of plant species in relation to different successional stages in a Chinese subtropical forest. Materials and methods This study selected four woody plant species, i.e. a pioneer tree Pinus 22 massoniana, a late-pioneer tree Quercus serrata, a mid-successional tree Cyclobalanopsis glauca and a late-successional tree Lithocarpus glaber in a Chinese subtropical forest. The outcomes of interspecific competition were investigated in the seedlings of three plant pairs, i.e. between Cyc. glauca and Pin. massoniana, between Que. serrata and Pin. massoniana, and between Lit. glaber and Que. serrata in a pot experiment. In the Cyc. glauca – Pin. massoniana combination, plants in monoculture and two-species mixture were uninoculated or inoculated with EM fungi Paxillus involutus, Pisolithus tinctorius, Cenococcum geophilum, Laccaria bicolor, and a mixture of these four fungal species. In the Que. serrata – Pin. massoniana and Lit. glaber – Que. serrata combinations, plants in monocultures and two-species mixtures were uninoculated or inoculated with EM fungi Pis. tinctorius, Cen. geophilum, Lac. bicolor, and a mixture of these three fungal species. EM root colonization rate and seedling biomass of each plant species were measured, and the outcomes of interspecific competition were estimated using competitive balance index after six months cultivation Important findings All EM fungal inoculation significantly promoted a competitive ability of the mid-successional tree Cyc. glauca over the pioneer tree Pin. massoniana compared with the uninoculated control treatment, and the extent to which EM fungi affected the outcome of interspecific competition was dependent on EM fungal identity in the Cyc. glauca and Pin. massoniana combination. EM fungal inoculation had no significant effect on the outcomes of interspecific competition 44 between the late-pioneer tree Que. serrata and Pin. massoniana combination and between the late-successional tree Lit. glaber and Que. serrata combination, compared with the uninoculated control treatment. However, amongst the EM fungal inoculation treatments the competitive ability of Que. serrata over Pin. massoniana was significantly higher in EM fungi Cen. geophilum and Lac. bicolor treatments than in Pis. tinctorius treatment. EM fungal diversity did not show a complementary effect on the outcomes of interspecific competition in all three plant pairs. This study demonstrated that the effect of EM fungi on the outcome of interspecific competition was dependent on the plant pairs tested in the subtropical forest ecosystem.

Cheng Gao, Liang-Dong Guo