Pristinity, degradation and replacement: The three dimensions of human impact on island vegetation

Abstract

This paper presents three extreme examples of the potential consequences of human settlement on the vegetation of oceanic and continental islands. The Neotropical Pantepui continental archipelago of sky islands is an example of pristinity, due to the almost nonexistent human impact that results from the remoteness and inaccessibility of these islands as well as the lack of natural resources to exploit. Easter Island is used to illustrate total vegetation degradation by deforestation and the exhaustion of natural resources, which has transformed the island into badlands with no signs of recovery. The Azores Islands have been chosen to illustrate replacement as, after initial postsettlement deforestation and extractive practices, a further transformative phase consisting of creating an almost totally anthropogenic vegetation with mostly exotic species occurred. The paper describes in some detail the developments of each case and the historical context in which they took place using historical, archeological and paleoecological evidence. Many intermediate states are possible among these three extremes, which can be represented with a ternary diagram (the PDR diagram), which is useful for characterizing the state of each island or archipelago in terms of human impact on terrestrial ecosystems and informing conservation and restoration practices.

Biodiversity crisis or sixth mass extinction?

“…The causes for their extinction were mostly anthropogenic, including overhunting, replacement by introduced species, deforestation, habitat destruction, increased land use, and/or introduction of alien pathogens. Size and connectivity constraints make oceanic islands especially sensitive to these disturbances (Rull, 2021).…”

Biodiversity crisis or sixth mass extinction?

“…The causes for the extinction of these species were mostly anthropogenic, including overhunting, replacement by introduced species, deforestation, habitat destruction, increased land use and/or introduction of alien pathogens. Size and connectivity constraints make oceanic islands especially sensitive to these anthropogenic disturbances (Rull, 2021).…”

Human Settlement and Landscape Anthropization of Remote Oceanic Islands: A Comparison between Rapa Nui (Pacific Ocean) and the Azores (Atlantic Ocean)

“…Human settlement and landscape anthropization of oceanic islands is a topical issue that is able to provide small-scale models for understanding the effects of anthropogenic pressure on ecological dynamics, thus informing biodiversity and ecosystem conservation [1][2][3]. Anthropogenic extinctions accelerated five centuries ago by the development of new navigation technologies, which made overseas travel significantly safer and more efficient.…”