Walking, cycling, picnicking in Nairobi’s lush Karura Forest, it is often hard to believe one is a mere two kilometres from the centre of one of Africa’s busiest cities. The woodlands are sprawling and serene, home to extraordinary biodiversity - indigenous plants and trees, 200 bird species, including Hawk and Africa Crowned eagles, owls, butterflies and colobus monkeys – which provide a sharp contrast to nearby fume-choked roads.