If you take a look at photos taken in the 19th century, you will discover that mountains in Hong Kong were not covered in the lush green vegetation we see today. In fact, large scale of afforestation work was started by the government only after the Second World War. In order to improve fertility quickly, the majority of trees planted were fast-growing exotic species that are effective in preventing surface runoff and soil erosion. Some examples are Paper-bark Tree and Taiwan Acacia – the former, which originates in Australia and has thick and soft bark, can withstand both droughts and floods; the latter, which has diazotrophs in its roots, can improve soil conditions. Both of them can be found in Twisk Nature Trail, a circular trail that starts and ends at Tsuen Kam Au. Apart from a wide variety of flora, there is more to the trail. For example, it is home to Golden Orb-web Weaver and Stick Insect, which is known for their camouflage. It also looks out on Tai Mo Shan at the helipad, introducing the volcanic rock terrain of the highest mountain in Hong Kong.