Comparison of production from an agroforestry system in a mid-rotation stand of Pinus pinaster with that from open pasture

Abstract

The growth, persistence and sheep carrying capacity of clover pastures grown in the open and under thinned stands of Pinus pinaster, and the responses of the trees to annual applications of superphosphate, with and without clover, were measured from the 15th to the 18th years of the rotation. Good clover establishment was achieved both under 90 trees/ha and in the open. In the second year, pastures under the stands of P. pinaster carried 93% of the numbers of sheep on pastures with no trees. By the fourth year, growth of the tree crowns had doubled their shading capacity and the relative carrying capacity of the pastures was 76%. Although significant increases in the soil levels of phosphorus, nitrogen and organic matter were recorded in the pastured and fertilized treatments, foliar analysis of pine needles showed no difference between fertilizer treatments. Except for potassium, foliar levels were at or below the levels regarded as adequate for growth. Annual increments in diameter and volume ranged from 1.4 to 2.1 cm, and 4 5 to 5.3 m3/ha, respectively. Whereas superphosphate increased diameter growth, superphosphate and clover together depressed diameter increment. Pinus pinaster and P. radiata are compared as agroforestry species.