Lost bioscapes: Floristic and arthropod diversity coincident with 12th century Polynesian settlement, Nuku Hiva, Marquesas Islands

Abstract

Knowledge of biodiversity in the past, and the timing, nature, and drivers of human-induced ecological change, is important for gaining deep time perspectives and for modern conservation efforts. The Marquesas Islands (Polynesia) are one of the world’s most remote archipelagos and illustrate the vulnerability of indigenous bioscapes to anthropogenic activities. Characterised by high levels of endemism across many biotic groups, the full spectrum of the group’s flora and fauna is nonetheless incompletely known. Several centuries of Polynesian settlement reshaped biotic communities in ways that are not yet fully understood, and historically-introduced mammalian herbivores have devastated the indigenous lowland flora. We report here on archaeological recovery of a diverse assemblage of plant and arthropod subfossils from a waterlogged deposit on the largest Marquesan island: Nuku Hiva. These materials offer new perspectives on the composition of lowland plant and arthropod communities pene-contemporaneous with human arrival. Bayesian analysis of multiple 14C results from short-lived materials date the assemblages to the mid-12th century AD (1129–1212 cal. AD, 95.4% HPD). Evidence for human activities in the catchment coincident with deposit formation includes Polynesian associated arthropods, microcharcoal, and an adzed timber. Plant macrofossils (seeds, fruits, vegetative structures) and microfossils (pollen, phytoliths) reveal coastal and lowland wet-moist forest communities unlike those observed today. Several apparently extinct taxa are identified, along with extant taxa currently constrained to high altitude and/or interior areas. A diverse inventory of subfossil arthropods—the first pre-18th century records for the islands—includes more than 100 distinct taxa, with several new archipelago records and one previously unreported for eastern Polynesia. The assemblages provide new insights into lowland Marquesan forest communities coincident with human arrival, and portend the considerable anthropogenic transformations that followed. These records also have implications for human colonisation of the Marquesas Islands and East Polynesia at large.

An archaeological review of Polynesian adze quarries and sources

“…This is also true for the large Tautama quarry on Pitcairn and the distant source in Colyers Island, Bluff Harbour, South Island, New Zealand. Although earlier habitation sites are known for the Marquesas (Allen et al., 2022), the isolated Eiao quarry complex was discovered at least by the thirteenth century. And at nearly the same time, the large quarries at Mauna Kea (McCoy et al., 2012) and Sāmoa (Leach & Witter, 1990) were not in use until a few centuries after colonisation of the islands.…”

Niche Construction and Long-Term Trajectories of Food Production

“…The contribution of these kinds of highly varied and complex landscape investments to ecological inheritances is reflected in well-documented archaeological histories from across the region, albeit usually discussed through other theoretical lenses. Another example of ecological inheritance comes from the Marquesas Islands, where Polynesian colonists introduced an array of economic plants (both root and tree crops), anthropophilic arthropods, and probably weedy plants around the 11th to 12th centuries AD (Allen et al 2022;Huebert and Allen 2020). To make way for shifting cultivation, the indigenous forest was cleared, initially from lowland regions and often assisted by firing, a common Polynesian technology.…”

“…Given the crucial role of birds in pollination and fruit/seed dispersal in the absence of native mammals, these losses undoubtedly disrupted ecosystem functioning, with potential cascade effects across trophic levels and food webs. Extinctions in herbaceous and arborescent plant taxa would have further weakened ecological webs in ways not yet fully understood (Allen et al 2022). As an example, one originally widespread lowland forest species (Sideroxylon sp.)…”