EFFECTS OF HURRICANE DAMAGE ON INDIVIDUAL GROWTH AND STAND STRUCTURE IN A HARDWOOD FOREST IN NEW-HAMPSHIRE, USA

1. Growth responses to hurricane disturbance were assessed for the dominant species in two sites in a northern-hardwood forest at Hubbard Brook, New Hampshire, USA. The species comprised two shade-tolerant trees, A cer saccharum (sugar maple) and Fagus grandifolia (American beech), one relatively shade-intolerant tree, Fraxinus americana (white ash) and one tree of intermediate tolerance, Betula alleghaniensis (yellow birch). The two sites, 0.6 km apart, were similar except for contrasting disturbance histories. The hurricane-damaged site was devastated by a hurricane in 1938, whilst the control site was only lightly damaged by the hurricane. Radial growth was compared between species, size classes, time periods and sites. 2. Radial growth of all species increased dramatically immediately following the hurricane in the damaged site; proportional growth increased more than sevenfold, on average. Radial growth remained high in the hurricane-damaged stand 49 years later. There was no change in radial growth in the control stand following the hurricane. 3. F. americana (the least shade-tolerant species) showed the greatest proportional increase in growth after the hurricane and maintained the highest growth rates several decades after disturbance. B. alleghaniensis, A. saccharum and F. grandifolia had very similar growth responses. Smaller trees had a greater proportional increase in growth than larger trees following the hurricane, especially for F. americana. 4. Stem density remained higher and mean tree basal area remained lower in the hurricane-damaged site than in the control site 49 years after the hurricane. 5. The pioneer species Prunus pensylvanica (pin cherry) invaded after the hurricane in the damaged site, but 49 years later was present only as dead stems, having been replaced by the later successional species B. alleghaniensis, A. saccharum, F. grandifolia and F. americana. This is the same successional sequence that follows clearcutting in northern-hardwood forests.