Leaf area, stemwood growth, and nutrition relationships in loblolly pine

Vose, J.M.; Allen, H.L.

Leaf area, stemwood growth, and nutrition relationships in loblolly pine

1988

Vose, J.M. | Allen, H.L.

The relationships among loblolly pine (Pinus taeda L.) stand leaf area index (LAI), stemwood volume growth (m3/ha/yr), and growth efficiency (m3 stemwood/ha/yr/LAI) were examined in three nitrogen (N) by phosphorus (P) fertilization field trials. Prior to fertilization, stocking levels and nitrogen limitations varied for the three stands. LAI increased significantly (up to 60%) following N fertilization on the two N deficient stands. Phosphorus additions did not affect LAI. Stenwood growth was positively and linearly related to LAI across treatments and stands. Variations in LAI across stands reflected the differences in stocking and N availability. On average, a unit of LAI produced 7.3 m3 stemwood/ha/yr. Growth efficiency was not affected by fertilization on two of the three stands. A decrease in growth efficiency at a projected LAI above 3.5 resulted from an asymptotic relationship between stemwood growth and LAI on a stand that was fully stocked and highly responsive to N fertilization. The use of LAI as an index of stocking is proposed because LAI intergrates tree size, stand density, and site resource supply. In addition, it is proposed that the deviation of a stand's current LAI from the maximum supportable LAI based on fixed site factors (e.g., water, temperature) may provide a good measure of a stand's potential responsiveness to fertilization. For. Sci. 34(3):547-563.

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