In Collapse: How Societies Choose to Fail or Succeed, Jared Diamond reviews the histories of societies that have failed in climates as diverse as Polynesia and the Arctic North. He identifies a handful of factors that were instrumental in those failures, but only one of those factors is shared by all the examples he describes: deforestation.
In every case deforestation reduced agricultural productivity by causing soil erosion and reducing rainfall. The roots of trees hold soil in place and absorb rainfall which would otherwise wash over the surface of the soil, flushing it into watersheds where it increases turbidity and destroys fisheries. The rainfall that is absorbed by the roots of trees is transpired by the leaves into the air where it rejoins the water cycle to be returned to the land as rainfall. When the trees are destroyed, the water cycle is interrupted in that location and rainfall is reduced.
In some cases, the loss of trees had a more immediate, observable effect on the society. On Easter Island, for example, the loss of trees quickly meant the loss of their main source of food: fish. Easter Island was the most easterly of the islands inhabited by Polynesians. It was far from any other island. Therefore, when their trees were gone and their boats eventually fell apart and could not be replaced, they had no means of fishing from their rocky shores. (see video)
Likewise, the Norse population in Greenland eventually starved to death when they could no longer grow the hay needed to keep their cows alive. In this frigid climate, they had used all of their trees as fire wood for warmth and to pasteurize the milk that was their principle food source. As their fuel source diminished, they burned the peat that fed their cows.
In both cases, as well as in others, these societies made choices that eventually contributed to their demise. The failure of their societies was not inevitable. On Easter Island, for example, the Polynesians chose to cremate their dead, unlike other Polynesians who bury their dead. And they devoted much of their time, effort, and resources to building the gigantic stone tributes to their ancestors. These stone sculptures were carved in quarries and then transported many miles by rolling them on logs. These cultural uses of wood were not essential to the islanders’ physical survival.
In Greenland, the Norse brought the cows from their homeland that were central to their culture. Their lives were devoted to keeping their cows alive by spending the brief summer growing the hay to feed the cows during the long winter in the huge stone barns in which the cows were protected from the extreme cold. The milk had to be boiled to prevent it from spoiling. As they depleted the wood needed to boil the milk, they simultaneously destroyed the land needed to grow the hay to feed the cows by burning the peat and causing erosion.
Meanwhile, the Inuit neighbors of the Norse made other choices that enabled them to survive in the harsh climate. They hunted whales and seals that were their principle food as well as the source of oil that heated their homes. The Norse considered the Inuit enemies with whom they did not interact or trade. Therefore, they were unable to learn these survival skills from them.
Diamond contrasts these histories with those of cultures that have made other choices. One of the most dramatic examples is the island of Hispaniola, shared by the nations of Haiti and the Dominican Republic. Haiti is almost entirely deforested and its ability to feed itself is destroyed by erosion. In contrast, the Dominican Republic is heavily forested because of a strong commitment to its forests made by its leadership. There are intervening factors, to be sure, but the deforestation of Haiti is a major factor in its impoverishment.
Diamond’s book intends to challenge us to look at the choices we are making for our own society. He asks and answers the rhetorical question, “Why did these societies make choices that contributed to their failure?” The short answer to that question is that long-term goals were sacrificed to short-term goals and that entrenched cultural practices were incapable of responding to changed conditions. When you are freezing cold today, you might choose to burn your last tree even if it means you don’t have any wood tomorrow. And when your entire diet is based on milk you can’t conceive that eating whale blubber may be a better choice for your long-term survival.
Million Trees sees these poor choices made by failed societies as similar to the poor choice that is now being made here in the Bay Area to destroy our non-native trees because we prefer native plants and trees.
We live in a place in which there were few trees prior to the arrival of Europeans. The landscape goal of native plant restorations is therefore grassland, scrub, and chaparral. Native trees are unlikely to survive in most of the places which are now forested by non-native trees. Native trees are being killed by Sudden Oak Death and bark beetle. Their historic ranges are changing in response to climate change. Releasing carbon sequestered in the trees and eliminating that source of carbon storage in the future will contribute to the greenhouse gases that result in climate change. Erosion is a likely consequence. Rainfall could be reduced by the absence of trees. Denuding our landscape of non-native trees is likely to result in a barren, weedy mess.
We urge native plant advocates to re-examine their demands for the destruction of non-native trees and plants in light of the changing climate which is exacerbated by deforestation. As Jared Diamond says as he concludes his book, “The other crucial choice illuminated by the past involves the courage to make painful decisions about values. Which of the values that formerly served a society well can continue to be maintained under new changed circumstances.”
We do not ask that native plant advocates abandon their preference for native plants. We encourage them to plant more native plants. We ask only that they quit destroying those that are not native.