A scrap of ground, the size of a tennis court, beside a river in Bristol is being transformed into a “tiny forest” featuring 600 trees as part of a nationwide initiative to bring more precious woodland into cities.  The area, on a plateau next to the River Trym in Southmead, will be one of a string of such projects across the UK featuring trees ranging from mighty oaks to birch, elder, blackthorn and guelder rose.  Over the next three years, the ambition is to plant more than 100 tiny forests, with spots already earmarked in Birmingham, Wolverhampton, Leicester and Glasgow.  The tiny forest in Southmead is part of a wider project called the Trym Valley Open Space Regeneration that aims to bring back trout to the waterway and includes the planting of the rare black poplar, on the river bank.