The journey through the centre of the island is along endless meadows and rolling hills. What stands out significantly is the lack of trees, which is the same for most of the island. There are patches here or there but most are not native to Rapa Nui.
When the first settlers arrived with some unsuspecting guests, the Polynesian rat, Rapa Nui was teeming with native palms and other large trees. Pollen and nut studies on the island suggest that they likely belonged to native, giant, palm trees similar to Jubaea, a Chilean sugar palm tree that grows up to 60ft (18m) in height.
The palm tree had many uses. A tapped palm tree would yield over 400 litres of sap that was used as a sweet and nutritious beverage. Its core would be harvested and the nuts collected for food. Along with other tree types, the palm was also used for thatching, making ropes and clothes, weaving mats and baskets, and building canoes, levers and sails.
The rats that hitched a ride found an abundance of food with no natural predators besides the humans. Feasting on the unlimited supply, they multiplied exponentially, doubling almost every six weeks.
Within a few centuries, the island could no longer sustain the excessive needs of its occupants nor its population growth. At its height, Rapa Nui had as many as 15,000 inhabitants and who knows how many rats. Usage outgrew new growth and by late 17th century the island was treeless.
The effects of overharvesting began with deforestation. With no trees, the islanders couldn’t build their canoes to fish, diminishing their food source and their ability to search for food elsewhere. Island-bound, they were also unable to reduce the population through migration.
Native land birds went extinct and the trees could no longer disperse their pollen. More than 20 plant species disappeared. With no supply of timber, the Moai could no longer be transported, thereby abandoning this ceremonial practice and replacing it with the Birdman Cult.
The Rapanui found themselves in an ecological trap. Famine followed causing significant social upheaval. By the time the Europeans’ arrived, the population dropped to around 2,000 inhabitants and the island was devoid of trees.
Today, Easter Island has only 5% arboreal coverage whilst two-thirds of it suffers from erosion caused by climate change with Poike the most affected. Reforesting programs are underway but given the island’s open and windy environment and lack of soil nutrients, the process will take time.
For now, the Australian eucalyptus tree seems to be doing well on the island regardless of the environment and I enjoyed seeing patches of them as I progressed towards Puna Rau.
Puna Rau is a small extinct volcano and the quarry of red scoria, the material used to make the pukao. The scoria is a type of volcanic ash that is highly porous with a reddish tint due to the iron oxide composition. It is soft and easy to carve making it a desirable rock for the pukao and other small items but unsuitable for large scale carvings like the Moai.
Given the sheer size and weight of the pukao, it is surmised that the islanders used their cylindrical shape to roll them on custom-built roads to their destination. It is also thought that the pukao was added to the Moai either by using ramps and rolling it on top of the standing statue or attaching it to the statue if in a lying position with ropes and then elevating it all as one piece.
Rolling off the hilltop, I make my way back to Hanga Roa.