Helford Expansion Programme
The Helford Expansion Programme is about human interaction with the effects of climate change. During the last ice age, much of what is now the UK was covered by glacial ice sheet, the rest was tundra affected by deep permafrost. The capture of much of the world’s water in ice caused a fall in sea level which created a land-bridge between the UK and continental Europe. This was not uniform throughout the entire English Channel as a depression in the mid channel made an inland sea. This would have been under sea-ice during glaciation. Given the deep cold in non-glacial areas at this time, very little in the way of plant-life would have survived, with most species retreating to refugia in Iberia, Italy and the Balkans. As the ice retreated, species began to recolonise land previously unsuitable for their survival.
Pedunculate oak made its way north from Iberia through France, across the land-bridges at Normandy and Brittany, into the UK at Cornwall and Kent and northwards from these entry points at a rate of approximately 50m per year. The oaks from the Iberian refugia make up the larger part of the pedunculate oak population of the UK. However, there are also oaks present in the UK from the Balkan refugia, characterised by somewhat later flushing of leaves than the Iberian haplotype. Given the geographic obstacles to the natural recolonization of trees from the Balkan refugia in the form of the Alps, Carpathians and Transylvanians, it is highly likely that the presence of the Balkan haplotype in the UK relatively quickly after vegetative recolonization is due to humanity as a dispersal vector.
Humanity has long valued oak as source of many useful materials, indeed the acorns themselves would have been a significant foodstuff to nomadic humans. When the UK was (re?)colonised by humanity following post-glacial warming, acorns from the Balkan refugia were carried here by those migrating people.
The Helford river basin is a unique example of Atlantic temperate rainforest with a very clear distinction between the dominant Iberian haplotype oaks and the scarcer Balkan haplotype. In this area of the UK, for some reason, the pedunculate oak has not hybridised as readily as throughout the rest of the archipelago. The Helford Expansion Programme seeks to continue the spread of pedunculate oak throughout the UK given that climate change is driving species northwards at rates not possible for static species such as trees. As humanity first carried oaks into Cornwall at a time of post-glacial warming, so again, we will carry oaks forward at a time of anthropogenic-induced global warming.
I have been unofficially planting oaks from the Helford basin of both haplotypes since 2001 and gradually working further eastwards and northwards. I am now beginning to document these previous plantings as well as increasing the output of current planting. The autumn of 2018 was a phenomenal mast-year for acorns and at present I have 600 oaks in trainer tubes which will be ready for planting over the next couple of years. Previously, the project had operated by simply burying acorns in threes (‘one for the jay, one for the mouse, one for the house’). The use of trainer tubes to plant semi-established trees with a compost starter should increase the success rate. Guerilla forestry.
