I guess it depends on the timing and the extent of the decline of trees. Jared Diamond’s assumption that an unsustainable tree collapse occurred before European

I guess it depends on the timing and the extent of the decline of trees. Jared Diamond’s assumption that an unsustainable tree collapse occurred before European arrival is a good one but this paper challenges some of the supporting evidence. As an alternative hypothesis, consider the impact of invasive species like rats on an island ecosystem. The tree level may have been very low but sustainable prior to the introduction of rats but the newly introduced perturbation may have caused full collapse.