As the human population grew, the wood was managed more and more intensively. Sufficient wood for cooking and heating houses could not be obtained by occasionally clearing fallow land. A herd of domesticated pigs produced more meat than the wild game which it largely replaced. They could be fattened on the acorn harvest in autumn then killed and salted with salt from the coast which was then nearer than the modern one. That would see food for most of the winter, then there would have to be recourse to fish from the fen or river. Christianity adopted this pattern in proposing the Lenten fast. From a time before the Romans were here, the wood had to be managed in an orderly way so as to get the most out of it without depletion.