Suffolk Bird Report 2004
Wood Larks in Breckland 1971-2004 The Impact of the Felling and Re-planting of the Forestry Commission's First Rotation Pine Crops on the Wood Lark Population in Breckland Ron Hoblyn Throughout the last decade, the Wood Lark Lullula arborea population of Breckland was probably higher than at any time in living memory. What follows is a brief account of how this has come about and is a story of two phases. Firstly, prior to about 1970, there is very little Wood Lark data in existence and because of this situation, it is impossible to say how common or otherwise the species was, with any degree of accuracy. Since 1970, however, there has been comprehensive and, apart from the foot and mouth year of 2001, continuous monitoring of the population right up to the present time, particularly in Thetford Foresi. Ali the data given in this paper refers to both the Norfolk and Suffolk parts of Breckland. Between 1922 and the beginning of the second World War, the Forestry Commission planted up 21000 hectares (52500 acres) of impoverished heathland and low grade arable, creating not only Britain's largest lowland forest (occupying 20% of Breckland), but also the largest man-made pine forest in Europe. This venture was eventually to have unforseen and long term benefits to certain scarce, traditionally heathland species, notably Wood Lark and Nightjar; both birds of conservation concern. It was widely known that Britain's Wood Lark population had been in decline throughout most of the 20th century, to the extent that in 1986, at the time of the first national survey, there were only an estimated 250 pairs in the country, probably an all-time low. This precarious situation was to dramatically change over the next two decades. During its establishment years and beyond, Thetford Forest contained very little suitable habitat for open ground species like Wood Lark, so consequently for several decades the species did not feature as it does today. On the sandy Breckland soils it is possible to grow pine to the âge of economie maturity in as little as 50 years, so that by 1970 the oldest crops of the first rotation were ready for felling, allowing the subséquent planting of the second rotation to begin. This felling/re-planting programme has been on-going for the past 35 years at the rate of 300-400 hectares (750-1000 acres) per year. There is stili more to come; to date approximately two-thirds of the forest has been managed in this way. Felling will now continue at a reduced annual amount until about 2020, with some 10% of the first rotation crops left to progress towards physical maturity as permanent retentions. The sheer scale of these fellings has brought about a dramatic change to the forest landscape, which is now a complex mosaic of uneven âge structure forest, invaluable to wildlife in general. Felling and re-planting provides Wood Larks with ail their essential habitat requirements of bare ground for foraging and sparse végétation for nesting. It is also usuai practice, whenever possible, to leave a scattering of the deadwood content of an area, or even the occasionai broad-leaved tree to act as perches, much favoured by the male Wood Lark as look-out posts. Clear-fell habitats are naturaily unstable and suitable only for a short period before tree-growth advances and excessive ground cover establishes. But as one area goes over, so another replaces it, enabling the Wood Lark to follow the pattern of the re-stocking in order to utilise the optimum sites. The period of suitability is directly related to ground cover, rather than tree height and as a general rule lasts approximately four to six years, depending on the particular site. The vast amount of habitat generated by felling regimes at Thetford, has been exploited by Wood Larks to an extent unrivalled in Britain. At the same time, the exploding forest population has served as a reservoir which has enabled the species to expand, not only into the heathland and arable sites found within and around the forest itself, but also farther 23