EFFECTS OF EXPERIMENTAL DEFOLIATION ON A POPULATION OF PEDUNCULATE OAK (QUERCUS ROBUR L.)

Abstract

SUMMARYAn experiment simulating defoliation at three levels of severity was conducted on 196 young oaks in a plot at Wolverhampton.In comparison with control plants, defoliation caused (1) earlier production of growth spurts (which are normal in undefoliated trees) and formation of more lateral branches, which were susceptible to winter frost damage; (2) production of more abundant, smaller leaves; (3) reduced diameters of main stems, from which can be calculated growth rates, varying with both defoliation treatment and growing conditions over the year, and returning to normal values as soon as defoliation ceased; (4) formation throughout the season of xylem of early wood type having a lower proportion of xylem fibres.With light defoliation, most of these responses were scarcely apparent, but with more severe defoliation, morphological effects dominated. The most noticeable effects of total defoliation were low growth rates and effects on wood anatomy.The results suggest that substantial natural defoliation could cause failure of regeneration, although in unshaded plots of young trees leaf loss results in retarded growth rather than death.

The expansion of native oakwoods into conifer cleared areas through planting

“…It has been shown that oak can survive repeated browsing by herbivores (Shaw, 1974;Hilton et al, 1987). Langbein (1997) found that oak saplings at or below the height of the surrounding field vegetation were often several years old, but remained at heights less than 35 cm and often less than 20 cm due to persistent browsing over the years.…”

Développement en hauteur des régénérations de Chêne sessile.

“…Conformément àde nombreux résultats obtenus en conditions contrôlées (Barnola et al ., 1990;Hilton et al .,1987;Ericsson etal .,1980),les feuilles,parvenant àleur taille finale, détournent àleur profit les nutriments quip ermettraient le développement des bourgeons. Cecie xpliquel e repos forcéd u bourgeon terminalaprès complèteé longation de l'UC1e t sa reprised 'allongement précoce sil es feuilles sont retirées.Cecie xpliqueé galement le démar-rage de ramifications sur l'UC1.…”

The Introduction and Manipulation of Woodland Field Layers: Seeds, Plants, Timing and Economics

“…Initially bluebell bulbs, (Hyacinthoides non-scripta) and clonal plants of Lamiastrum ga/eobdo/on, (yellow archangel), and Oxalis acetosel/a, (wood sorrel), were planted in a 9 year old experimental oak plantation (HILTON, PACKHAM, and WILLIS, 1987) to which four litter treatments had been applied in a Latin square design (Fig. 1).…”