Abstract
This study addressed whether competition under different light environments was reflected by changes in leaf absorbed light energy partitioning, photosynthetic efficiency, relative growth rate and biomass allocation in invasive and native competitors. Additionally, a potential allelopathic effect of mulching with invasive Prunus serotina leaves on native Quercus petraea growth and photosynthesis was tested. The effect of light environment on leaf absorbed light energy partitioning and photosynthetic characteristics was more pronounced than the effects of interspecific competition and allelopathy. The quantum yield of PSII of invasive P. serotina increased in the presence of a competitor, indicating a higher plasticity in energy partitioning for the invasive over the native Q. petraea, giving it a competitive advantage. The most striking difference between the two study species was the higher crown-level net CO2 assimilation rates (Acrown) of P. serotina compared with Q. petraea. At the juvenile life stage, higher relative growth rate and higher biomass allocation to foliage allowed P. serotina to absorb and use light energy for photosynthesis more efficiently than Q. petraea. Species-specific strategies of growth, biomass allocation, light energy partitioning and photosynthetic efficiency varied with the light environment and gave an advantage to the invader over its native competitor in competition for light. However, higher biomass allocation to roots in Q. petraea allows for greater belowground competition for water and nutrients as compared to P. serotina. This niche differentiation may compensate for the lower aboveground competitiveness of the native species and explain its ability to co-occur with the invasive competitor in natural forest settings.
Highlights
Competition among trees results from genetically founded species-specific and ontogenetic differences in growth dynamics, maximum net CO2 assimilation rate (Amax), leaf nitrogen concentration (Nmass) and requirements for nutrients, water and light (Craine and Dybzinski 2013; Reich et al 1992)
Our results show that the acclimation of leaf absorbed light energy partitioning is more strongly affected by light environment than by competition and allelopathy (Tables 1, S1; Figs. 1, 2)
We expand on prior studies by focusing on interspecific competition for light and its effect on partitioning of light energy into three competing processes: ΦPSII, ΦNPQ, and Φf,D
Summary
Competition among trees results from genetically founded species-specific and ontogenetic differences in growth dynamics, maximum net CO2 assimilation rate (Amax), leaf nitrogen concentration (Nmass) and requirements for nutrients, water and light (Craine and Dybzinski 2013; Reich et al 1992). On a global scale across biomes and plant functional groups there is evidence that key leaf traits such as specific leaf area (SLA), Nmass, Amax and dark respiration (Rd) are positively related (Reich et al 1998). It is difficult to distinguish the effects of different environmental factors on plant. Journal of Plant Research (2018) 131:505–523 performance from plant–plant competitive interactions or allelochemical relations. The outcomes of plant competition can be identified more in controlled conditions. In a pot experiment, we simulated the relationship between Quercus petraea and Prunus serotina seedlings under the canopy of a Scots pine forest, which has been observed in natural conditions
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