Document: DON-3-64-5

Regeneration from seed in artificial treefall gaps: Replacing plantation pine with native forest in New Zealand.

DRAKE, D.R.* and K.G.MCALPINE

Victoria University of Wellington, Wellington, New Zealand ¹

Abstract:
Treefall gaps were created in a relictual Pinus radiata plantation in New Zealand to determine how pine removal would affect regeneration by native and alien plants during forest restoration. Based on exposure to sunlight, gaps were divided into five microsite types (plus closed-canopy controls) in which seedling emergence and establishment were measured. Seedling emergence from the seed bank, measured 10 wk after gap formation in 216 transplanted, homogenized soil samples, was positively correlated with exposure and ranged from 8624/m² in the sunniest microsites to 4235/m² in the shadiest microsites, and 3331/m² in the controls. The addition of 3cm of pine leaf litter promoted seedling emergence in sites exposed to sunlight but affected emergence less consistently elsewhere. Alien seedlings comprised 23% of the individuals in the sunniest microsites, but only 13% in closed forest. In 180 permanent plots examined one yr after gap formation, seedling establishment ranged from 110/m² in the sunniest microsites to 42/m² in the shadiest microsites, and 4/m² under closed forest. Alien shrubs (chiefly Cytisus scoparius) comprised 68% of the seedlings in the sunniest microsites, but only 20% in closed forest. Results suggest that pines may be replaced by native trees without an intervening alien shrub stage if pines are slowly thinned over time, thus minimizing exposure of soil to direct sunlight.

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This abstract is being presented at: 11:00 AM in session:
Oral Session #60: Forest Restoration.