Improved nutritional status of Cupressus lusitanica when grown adjacent to Pinus radiata

Abstract

We examined how a mixture of Pinus radiata D. Don and Cupressus lusitanica Mill. influences foliage element concentrations at 20 sites, covering a fertility gradient. Foliage element concentrations of plants at plot boundaries, where the two species grew adjacent to each other, were compared with those of plants at plot centres, where they were surrounded by plants of the same species. For C. lusitanica, plot position significantly affected nitrogen (N), phosphorus (P), and sulphur (S) with concentrations of these elements at the plot boundary exceeding concentrations at the plot centre by 10%–14%. For P. radiata, plants at the plot boundary had a significantly greater P concentration and lower N/P ratio than plants at the centre, but differences between positions were less than that for C. lusitanica (<7%). For C. lusitanica, the difference between foliage concentrations of N and P at the plot boundary and centre significantly declined as the mean plot concentrations of these elements increased. It is likely that C. lusitanica at the boundary benefited from the greater availability of N, P, and S in the root rhizosphere, where they were mobilized from soil organic matter by the ectomycorrhizae of P. radiata. We also suggest that P. radiata at the plot boundary may have benefited from mobilization of P by the endomycorrhizae of C. lusitanica.