Looking at the conclusion, Diamond is criticized for not being scientific. Perhaps, the paper was submitted before the publication of this:

Easter Island Deforestation
B. Rolett & Jared Diamond.2004. “Environmental predictors of pre-European deforestation on Pacific Islands,” Nature 431: 443-446 (September 28)

Abstract

Some Pacific island societies, such as those of Easter Island and Mangareva, inadvertently contributed to their own collapse by causing massive deforestation. Others retained forest cover and survived. How can those fateful differences be explained? Although the answers undoubtedly involve both different cultural responses of peoples and different susceptibilities of environments, how can one determine which environmental factors predispose towards deforestation and which towards replacement of native trees with useful introduced tree species? Here we code European-contact conditions and nine environmental variables for 81 sites on 69 Pacific islands from Yap in the west to Easter in the east, and from Hawaii in the north to New Zealand in the south. We hereby detect statistical decreases in deforestation and/or forest replacement with island rainfall, elevation, area, volcanic ash fallout, Asian dust transport and makatea terrain (uplifted reef), and increases with latitude, age and isolation. Comparative analyses of deforestation therefore lend themselves to much more detailed interpretations than previously possible. These results might be relevant to similar deforestation-associated collapses (for example, Fertile Crescent, Maya and Anasazi) or the lack thereof (Japan and highland New Guinea) elsewhere in the world.

p. 445. “ We can now reconsider why Easter Island suffered almost the most extreme deforestation and consequent social and population collapse of any pacific island even though the Polynesians who colonized Easter colonized hundreds of other islands without wreaking such extreme impacts. Our study suggests part of the answer to be Easter’s extreme environmental fragility predisposing toward deforestation: of our 69 islands, it has the lowest tephra and dust fallout, the second greatest isolation and third highest latitude and no makatea, and is relatively low, small and dry. On the basis of those independent variables, our multiple regression and tree models predict correctly that Easter should have the third highest deforestation score, exceeded only by Necker and Nihoa, which also ended up completely deforested. That is, Easter’s collapse was not because its people were especially improvident but because they faced one of the Pacific’s most fragile environments.”

Bernard