Fourth episode examines how plants either share environments harmoniously or compete for dominance within them. Attenborough highlights the 1987 hurricane and the devastation it caused. However, for some species, it was that opportunity for which they had lain dormant for many years. The space left by uprooted trees is soon filled by others who move relatively swiftly towards the light. The oak is one of the strongest and longest-lived, and other, lesser plants nearby must wait until the spring to flourish before the light above is extinguished by leaves. Tropical forests are green throughout the year, so brute force is needed for a successful climb to the top of the canopy: the rattan is an example that has the longest stem of any plant. As its name suggests, the strangler fig 'throttles' its host by growing around it and cutting off essential water and light. Some can take advantage of a fallen tree by setting down roots on the now horizontal trunk and getting nutriment from the surrounding moss and the fungi on the dead bark. The mountain ash (eucalyptus regnans) grows so tall, that regeneration becomes a considerable problem. It is easily flammable, so its solution is to shed its seeds during a forest fire and sacrifice itself. It therefore relies on the periodic near-destruction of its surroundings in order to survive. Attenborough observes that catastrophes such as fire and drought, while initially detrimental to wildlife, eventually allow for deserted habitats to be reborn.

What was the Wehrmacht? A group of obedient yeasayers? A murdering band of thugs? An army of millions of abused young men? This series in 5 parts provides differentiated and conclusive answers based on the latest historical and comprehensive investigative research, bringing many new facts to light – among them documents proving for the first time ever, what many among the officers actually thought. Blitzkrieg, the lightning war, in German incorporate modern weapons and vehicles as a method to help avoid the stalemate of trench warfare and linear warfare in future conflicts. The first practical implementations of these concepts coupled with modern technology were instituted by the Wehrmacht in the opening theatres of World War II. The strategy was particularly effective to Germany in the invasions of Western Europe and initial operations in the Soviet Union. These operations were dependent on surprise penetrations, general enemy unpreparedness and an inability to react swiftly enough to German offensive operations.

Author Henry Hitchings explores the lives and works of Britain's radical and pioneering 18th-century novelists who, in just 80 years, established all the literary genres we recognise today. It was a golden age of creativity led by Daniel Defoe, Jonathan Swift, Henry Fielding, Laurence Sterne, Fanny Burney and William Godwin, amongst others. Robinson Crusoe, Gulliver's Travels, Tom Jones and Tristram Shandy are novels that still sparkle with audacity and innovation. On his journey through 18th-century fiction, Hitchings reveals how the novel was more than mere entertainment, it was also a subversive hand-grenade that would change British society for the better. He travels from the homes of Britain's great and good to its lowliest prisons, meeting contemporary writers like Martin Amis, Will Self, Tom McCarthy and Jenny Uglow on the way.

The Cave of Swallows in Mexico is a 400m vertical shaft, deep enough to engulf the Empire State Building. The Lechuguilla cave system in the USA is 193km long and 500m deep with astonishing crystal formations hanging from its chambers. Although often overlooked, caves are remarkable habitats with equally bizarre wildlife. Cave angel fish cling to the walls behind cave waterfalls with microscopic hooks on their flattened fins. Cave swiftlets navigate by echo-location and build nests out of saliva. The Texas cave salamander has neither eyes nor pigment. Unique access to a hidden world of stalactites, stalagmites, snotites and troglodytes brings a wealth of surprises.