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The effect of dormant season applications of triclopyr on the growth and survival of young trees was investigated in two experiments using transplants grown for one season beneath a canopy of Corsican pine prior to treatment with varying concentrations of herbicide. In one experiment, transplants of ash, beech and oak were initially grown with or without competition from bramble. In the second experiment, birch, hazel, oak, Scots pine, Douglas fir and Japanese larch were grown without competition from bramble or other ground flora. Bramble reduced survival and growth of oak and appeared to reduce the tolerance of ash, oak and beech to herbicide applications. Although the precise effect of the herbicide differed between experiments, where adverse effects on survival and growth were found these only occurred at dose rates of 1.92 and 2.88 kg a.i. ha−1 and even at these rates some of the species used were unaffected. With the exception of oak and beech in one experiment, survival exceeded 90 per cent at the end of the first growing season after application of herbicide, regardless of dose rate. The same pattern of results was found for height and diameter increments. In a third experiment, dormant season applications of triclopyr reduced bramble cover but appeared to have little effect on other ground flora species. The work reported here indicates that where bramble is threatening to outcompete and kill young tree seedlings application of 0.96 kg a.i. ha−1 triclopyr (equivalent to 2 l ha−1 Timbrel, 480 g l−1 triclopyr; Dow AgroSciences) in water in the winter season can effectively control bramble, while leaving deeply dormant seedlings of oak, beech, ash, birch, hazel, Scots pine, Douglas fir and Japanese larch unharmed. [ABSTRACT FROM AUTHOR]

Silvicultural systems which retain canopy cover during the regeneration phase have become an increasingly important form of management, but their effectiveness in controlling weed species has not been extensively studied. The development of bramble, which is a widespread competitive weed species, was observed within a c. 35-year-old Corsican pine stand thinned to remove 10, 20, 40 and 80 per cent of basal area. Cover, height and numbers of inflorescences and berries were recorded in each of the 3 years following thinning and were generally ranked according to intensity of thinning, but there were no significant differences between treatments. Shoot length, estimated using a grid-intersection method, was significantly lower in the 10 per cent compared with the 40 and 80 per cent thinning treatments. The initial length of bramble shoot present, and basal area and number of trees remaining could be used in various combinations to predict cover, height and shoot length. Although the bramble thicket was generally less well developed in the less-intense thinning treatments, these did not appear to enhance the establishment of trees. Seedlings grew best in the 80 per cent treatment and overall their mean heights were generally lower than that of bramble. Retention of overstorey cover in order to suppress bramble growth and promote tree seedling establishment during forest regeneration may not succeed. [ABSTRACT FROM AUTHOR]

Bramble is a prickly shrub that may facilitate the establishment of tree seedlings at sites where grazing animals are present, but its role in forest regeneration is less clear. This study took place in a beech woodland over the 5-year period immediately after a heavy thinning to leave a basal area of 6.5 m2 ha−1. Development of the ground flora and the growth and browsing of birch and willow seedlings were observed annually at the end of the summer. The ground flora became dominated by a dense thicket of bramble c. 60 cm tall. The tree species differed in their susceptibility to browsing with a greater percentage of willow being browsed than birch. Similarly, willow seedling mortality was greater. Over the 5-year period, the average height of birch reached c. 2 m compared with c. 0.6 m for willow. For both species, there were significant positive relationships between seedling height and diameter and bramble cover and heights indicating that bramble facilitates the establishment of both willow and birch. Bramble reduced the incidence of browsing, an effect which appeared to be due to its relationship with seedling size. The potential role of bramble in the facilitation of naturally regenerating tree seedlings within woodlands is discussed. [ABSTRACT FROM PUBLISHER]

There is much literature on natural regeneration which emphasizes the importance of good seed year, but few authors consider seed input in terms of the combination of seed quantity (i.e. number of seeds) plus seed quality (i.e. percentage of viable seeds). We have considered both aspects and also attempted to identify the proportions of good vs poor quality seeds contributing to natural regeneration via 'seed rain' vs 'cone drop'. In addition to studying seed input, we looked at the effects of vegetation control, ground preparation and protection from small mammals on seedling emergence and survival. Over a 3-year period (February 2001 to March 2004), there was enough seed production and seedling survival to conclude that natural regeneration could be successful beneath a 50-year-old stand of Corsican pine in the south of England. Peaks of pine seed release occurred in March/April in 2002 and 2003, but it was extremely surprising to observe that some seed was trapped in virtually every month of the 3-year study, demonstrating an almost continual release of (at least) small quantities of seeds. In line with this finding, although most pine seedlings were found shortly after peak seed dispersal in May, June and July; new seedlings were found in every month throughout the study except February and October. In general, vegetation control and ground preparation had a positive effect on seedling survival; the probability of a seedling surviving for 300 days was between SO and 60 per cent. [ABSTRACT FROM AUTHOR]

Observations to follow the development of 2-year-old oak seedlings took place over a 6-year period at a fenced site within a mature stand of oak in southern England. Bramble and bracken were abundant, but the cover of other species was low. Although seedlings doubled in height, only 13 per cent survived and few were taller than either bramble or bracken. The initial number of seedlings was inversely related to both canopy cover and distance to the nearest parent tree. The final number of seedlings could be predicted from the initial percentage covers of bramble and bracken, and either the overstorey canopy cover or the initial number of seedlings. The average annual rate of seedling mortality, which was 25-50 per cent, was significantly influenced by the vegetation present. Grass was positively related to survival whereas there was an inverse relationship with both bramble and bracken cover. Models estimated -80 per cent annual seedling survival at -25 per cent bramble cover but only 50 per cent at -60 per cent cover. Although grasses can be competitive species, results indicate that oak seedling establishment may be better in areas with a ground flora comprising grass. [ABSTRACT FROM AUTHOR]