Islands are among the last regions on Earth settled and transformed by human activities, and they provide replicated model systems for analysis of how people affect ecological functions. By analyzing ...27 representative fossil pollen sequences encompassing the past 5000 years from islands globally, we quantified the rates of vegetation compositional change before and after human arrival. After human arrival, rates of turnover accelerate by a median factor of 11, with faster rates on islands colonized in the past 1500 years than for those colonized earlier. This global anthropogenic acceleration in turnover suggests that islands are on trajectories of continuing change. Strategies for biodiversity conservation and ecosystem restoration must acknowledge the long duration of human impacts and the degree to which ecological changes today differ from prehuman dynamics.
In this research we identify the processes leading to hierarchical society in a region of Sāmoa, the often-labelled ʻbirthplace’ of the Polynesian chiefdoms. Our analyses in the Falefa Valley on ...ʻUpolu island combine lidar mapping and ground survey to reveal an extensive system of archaeological features: rock walls, ditches, and platforms. Excavation and radiocarbon dating underpin a feature chronology and characterize feature variation. Soil nutrient analyses and geoarchaeological coring indicate spatial differences in the agricultural potentional of the valley and human modification of the environment over time. Our results demonstrate that the construction of large rock walls, some several hundred meters long, began approximately 900–600 years ago, shortly after rapid population rise in Sāmoa. This was followed by the building of small rock walls, often enclosing rectilinear fields or platforms. Both rock wall types are concentrated in the western and northern regions of the valley and greater rock wall densities are associated with areas of higher agricultural potential. The earliest wall construction was penecontemporaneous with partial forest removal that created a more productive wetland environment in the southeastern region of the valley, an area later a focus of agricultural ditching. We propose that with population rise the variable fertility of agricultural land became a significant resource gradient, influencing the population in two ways. First, areas of more fertile agricultural land promoted territorial behaviour, including large rock walls, and led to a collective action problem. Second, niche construction in the form of human-induced environmental change created a productive wetland agricultural system that was enhanced with a reticulate ditch network, the maintenance of which also led to a collective action problem. We conclude that in the Falefa Valley, the second largest catchment in Sāmoa, collective action problems were the cause of increased social hierarchy and may underlie the origins of chiefdoms throughout Polynesia.
Polynesians introduced the tropical crop taro (Colocasia esculenta) to temperate New Zealand after 1280 CE, but evidence for its cultivation is limited. This contrasts with the abundant evidence for ...big game hunting, raising longstanding questions of the initial economic and ecological importance of crop production. Here we compare fossil data from wetland sedimentary deposits indicative of taro and leaf vegetable (including Sonchus and Rorippa spp.) cultivation from Ahuahu, a northern New Zealand offshore island, with Raivavae and Rapa, both subtropical islands in French Polynesia. Preservation of taro pollen on all islands between 1300 CE and 1550 CE indicates perennial cultivation over multiple growing seasons, as plants rarely flower when frequently harvested. The pollen cooccurs with previously undetected fossil remains of extinct trees, as well as many weeds and commensal invertebrates common to tropical Polynesian gardens. Sedimentary charcoal and charred plant remains show that fire use rapidly reduced forest cover, particularly on Ahuahu. Fires were less frequent by 1500 CE on all islands as forest cover diminished, and short-lived plants increased, indicating higher-intensity production. The northern offshore islands of New Zealand were likely preferred sites for early gardens where taro production was briefly attempted, before being supplanted by sweet potato (Ipomoea batatas), a more temperate climate-adapted crop, which was later established in large-scale cultivation systems on the mainland after 1500 CE.
Aim: To reconstruct ecological changes from the fossil record of a unique wetland on the tropical oceanic island of Tahiti, between 44.5 and 38 cal. kyr BP. Location: Vaifanaura'amo'ora, Tamanu ...Plateau, Punaru'u Valley, Tahiti, Society Islands, French Polynesia (17°38'S, 149°32’50”E). Methods: Fossil pollen, spores, seeds, diatoms and invertebrates were examined from a 3.7 m core consisting of Pleistocene-aged algal sediment overlain by late Holocene peat. Results: Between 44.5 and 41.5 cal. kyr bp, Ficus trees, sub-shrubs including Sigesbeckia orientalis L., the C₄ grass species Paspalum vaginatum Sw., and extinct Pritchardia palms dominated the Vaifanaura'amo'ora wetland. This vegetation association is no longer present in the tropical oceanic Pacific islands. After 41.5 cal. kyr BP, the climate rapidly became drier and cooler with grasses, sedges and ferns dominating the vegetation. Algal sediment accumulation ceased after 38 cal. kyr bp due to prolonged dry climate conditions recorded across the Pacific Ocean. Sediment accumulation recommenced in the late Holocene. Main conclusions: The ecological responses identified from Tahiti provide evidence counter to the prevailing view that the tropical oceans buffered the ecological effects of abrupt climate changes during the last glacial period.
Palynological records from Holocene wetland deposits in East Polynesia have demonstrated widespread ecological changes following Polynesian arrival after c. ad 1200, but linking inferences of human ...activities to archaeological records has been limited by equivocal fossil proxies and a lack of chronological controls. To address these limitations, multiple sedimentary profiles were examined from a coastal marsh on the remote East Polynesian island of Rapa. These profiles span 8000 years of ecological change and record mid-Holocene sea-level highstand conditions which receded to modern levels by ad 500. Depositional models were constructed for each profile using Bayesian inferences to characterise the spatial and temporal changes in fossil proxy representation. Just prior to human arrival there are high pollen concentrations of Pandanus and the presence of an extinct palm, both indicative of an extensive lowland swamp forest that developed after ad 500. Indicators of Polynesian arrival and agricultural expansion include unprecedented amounts of charcoal particles and pollen from the introduced cultigen, Colocasia esculenta (taro). The swamp forest was progressively cleared, beginning in the most inland section at ad 1110–1230. The Colocasia-based agricultural system reached its greatest extent from ad 1590 to 1740. The last appearance of the extinct palm was recorded at ad 1520–1660 and the entire area was cleared of indigenous trees soon after European colonisation at ad 1830–1880. By modelling the chronologies of individual fossil proxies across each profile, we have developed a framework for defining the processes behind vegetation change and for matching palynological-based inferences of human activity with archaeological records.
ABSTRACT
The lateness and prominence of Polynesian colonisation of New Zealand make it an ideal place to investigate the Anthropocene. We review the Anthropocene as a process and the information ...needed to understand the consequences of ongoing human–environmental interaction. Elsewhere in the world, a lengthy history complicates the ability to differentiate between the impact of people on the environment and the consequences of engagement. In New Zealand, engagement is not only of short duration but the landmass has a long coastline, with numerous offshore islands. These characteristics provide the scope to study the impact of engagement where it is particularly discernible. We introduce one such island, Ahuahu (Great Mercury Island). Upon arrival, Polynesian colonists found a temperate, geologically complex land covered in forest, populated by a diverse endemic flora and fauna. They knew how to produce crops and exploit wild food sources but had to rapidly adapt to new conditions marginal to production and new technological possibilities. The New Zealand case study allows consideration of whether the processes involved in creating the phenomena described by the Anthropocene are global, directional and inevitable, or are due to local, small‐scale changes related to particular forms of production by Māori, and their capacity to construct environmental change.
RÉSUMÉ
Le retard et la proéminence de la colonisation Polynésienne de la Nouvelle‐Zélande en font un lieu idéal pour étudier l'Anthropocène. Nous examinons l'Anthropocène en tant que processus et les informations nécessaires pour comprendre les conséquences d'une interaction continue avec l'environnement humain. Ailleurs dans le monde, une longue histoire complique la capacité à différencier l'impact des personnes sur l'environnement et les conséquences de l'engagement. En Nouvelle‐Zélande, l'engagement est non seulement de courte durée, mais la masse terrestre a un long littoral avec de nombreuses îles au large des côtes. Ces caractéristiques permettent d'étudier l'impact de l'engagement là où il est particulièrement discernable. Nous présentons une de ces îles, Ahuahu (Great Mercury Island). À leur arrivée, les colons Polynésiens ont trouvé une terre tempérée et géologiquement complexe recouverte de forêts peuplées d'une faune et d'une flore endémiques diverses. Ils savaient produire des récoltes et exploiter des sources alimentaires sauvages, mais devaient s'adapter rapidement à de nouvelles conditions marginales à la production et à de nouvelles possibilités technologiques. L’étude de cas Néo‐Zélandaise permet de déterminer si les processus impliqués dans la création des phénomènes décrits par l'Anthropocène sont mondiaux, directionnels et inévitables, ou sont dus à des changements locaux à petite échelle liés à des formes particulières de production des Maoris et à leur capacité à construire des changements environnementaux.
TUHINGA WHAKARĀPOPOTÓ
Ki te aro atu ki te ao whānui, he nohonga hou a Aotearoa. Nā tēnā, he whenua pai mā ngā mahi ketuketu o te Anthropocene. Ka whaia te Anthropocene kia whai māramatanga ki te mahi o te tangata i tāna nohonga i te whenua, me āna pānga ki te taiao. Kia tahuri ki whenua kē, nā te roa o te nohonga o te tangata i ō rātou whaitua, he mahi uaua kia wetewetehia ngā tohu i te whenua, nā te tangata i ā rātou e noho‐tahi ana i taua taiao, puta noa i te ao. Heoi, kei Aotearoa, he poto te wā o te nohonga o te tangata, ā, he tahatika roroa i tai me te maha hoki o ngā moutere iti e tū ana i tai. Nā aua kitenga, ka taea te tātari te hononga o te tangata ki te taiao me ngā nukuhanga o roto. Ko Ahuahu tētahi moutere pērā. I te taenga mai o ngā iwi o te Moana nui a Kiwa i kitea e rātou tētahi wāhi hātai, he hopunga nā Tāne, mā āna tamariki, arā, ngā otaota, ngā rākau, ngā ngangara, ngā manu hoki. I a rātou ngā māramatanga o te mahinga kai, o te rāweke i ngā hua o Haumie hoki. Heoi, nā te mea e rerekē ana te taiao katoa, ngā rākau, ngā paru, i tere urutau rātou ki ngā rerekētanga me ngā mea hou, hei hangarau hou mā rātou anō. Ā, mā tēnei rangahau i Aotearoa, ka āhei te kite, mehemea, kotahi anake te tininga rerenga o te Anthropocene i te ao whānui. Mehemea, e rerekē ana rānei te rere o tērā, o tērā o ngā whaitua, nā te hunga noho me ā rātou mahi ki te taiao.
The lateness and prominence of Polynesian colonisation of New Zealand makes it an ideal place to investigate the Anthropocene. Elsewhere in the world, a lengthy history complicates the ability to differentiate the impact of people on the environment and the consequences of engagement. In New Zealand, engagement is not only of short duration but the landmass has a long coastline with numerous offshore islands. We introduce one such island, Ahuahu, Great Mercury Island that illustrates the way Māori interacted with the environment. The case study illustrates measures of vegetation change, erosion and deposition, including artefact movement as illustrated in the figure, that allows consideration of whether the processes involved with the Anthropocene are global, directional and inevitable, or are due to local, small‐scale changes related to particular forms of production by Māori, and their capacity to construct environmental change.
Hydrogen isotope ratios (2H/1H or δ2H) were measured in lipid biomarkers from algal, plant and microbial sources in sediment cores from a lake and a peat bog on the small, sparsely-inhabited ...Washington Island (4°43′N, 160°25′W) to assess central equatorial Pacific hydroclimate conditions during the last millennium. High δ2H values in lipids from a variety of biological sources indicate that the driest period of the last millennium occurred ∼1450–1600 CE, during the first half of the Little Ice Age (LIA; 1450–1850 CE). An Intertropical Convergence Zone (ITCZ) located south of its modern position, less frequent and/or weaker El Niño events, and/or a La Niña-like mean state in the tropical Pacific are potential causes for this drying at Washington Island. From ∼1600 to 1650 CE, an abrupt transition to modern-like low δ2H values in phytoplankton, plant, and microbial lipids occurred, signaling the establishment of a high-rainfall regime similar to that observed today. This transition coincided with increased ENSO variability, an excess of central-Pacific relative to eastern-Pacific El Niños, and a decline in the zonal SST gradient across the tropical Pacific, reflecting an El Niño-like mean state. The Medieval Warm Period (MWP; 900–1250 CE) was characterized by high δ2H values in lipids from phytoplankton (dinosterol, dinostanol), bacteria (hop-21-ene), and vascular plants (sitostanol), and by extension a drier climate relative to the modern lake. An increasing δ2H trend through the MWP in lipids from all sources implies drying as Northern Hemisphere temperatures declined from the early to the late MWP. This drying is hypothesized to have been driven by extensive volcanism in northern, southern, and tropical latitudes, all of which tend to cause zonal mean drying at the latitude of WI (5°N). Finally, the transition period between the LIA and MWP ∼1250–1450 CE was characterized by declining δ2H values of plant and microbial lipids in peat sediments, indicating a trend toward wetter conditions; in the absence of known internal or external climate forcings, this may have been a regional or local event. This study demonstrates that the application of compound-specific δ2H measurements of lipids from multiple biological sources and in multiple sedimentary archives from a single location can yield hydroclimate reconstructions with higher confidence than those based on single lipids. Such reconstructions are particularly important in the vast tropical Pacific, where few hydroclimate records exist.
•Hydroclimate reconstructed from δ2H values of algal, plant & microbial biomarkers.•Lake & peat bog sediment cores from Washington Island, central equatorial Pacific.•Driest period of the last millennium was the early Little Ice Age 1450–1600 CE•Abrupt transition to modern high-rainfall regime occurred 1600–1650 CE
This dissertation evaluates the effect of gait modifications on the joint reaction forces (JRF) estimated via computer simulation using the OpenSim software tool. Osteoarthritis (OA) of the knee is a ...common and progressive condition that can lead to the need for a full or partial joint replacement. Identifying interventions that can slow the progression of the disease can help improve the quality of life and reduce impairments to activities of daily living in those diagnosed with knee OA. Modified gait interventions are a common approach that seek to reduce the loading in the knee joint, and significant research has demonstrated gait modifications’ effect on the knee adduction moment (KAM) and knee flexion moment (KFM). The KAM and KFM are common surrogate measures of joint loading and many gait interventions have been shown to reduce KAM and/or KFM. Recent advances in computer technology have enabled more efficient and practical use of simulation for estimating the joint reaction forces in the knee during a variety of tasks, such as walking and running. These approaches are often validated using data from subjects with instrumented knee implants and their accuracy and use have been growing. This dissertation covers 3 independent studies that sought to estimate the effect of gait interventions on the JRF in the knee. The first study used existing data published in the biomechanics community, via the Grand Challenge Competition to Predict in Vivo Knee Loads, to validate the use of the Lerner knee model in participants implementing 2 common gait interventions: the medial knee thrust (MKT) and the lateral trunk lean (LTL). The second study built on the first and implemented the simulation approach in 20 healthy participants who performed 3 gait modifications: the toe-in gait (TIG), the MKT, and the LTL. The final project of this dissertation research was a 10-week randomized controlled trial (RCT) that used real-time biofeedback (RTB) to implement the LTL in participants diagnosed with medial compartment knee OA. The results of this work validated the use of the Lerner knee model in modified gait, such as MKT and LTL. They also provided evidence to suggest that the LTL may not be as effective as previously thought at lowering the JRF in the medial compartment of the knee. Further work is needed to validate these findings and directions of future research are also discussed.
•Palmitone is a dominant leaf wax constituent of Colocasia esculenta (taro) leaves.•Palmitone is not present in common indigenous plants and other cultivars in Vanuatu.•Palmitone is present in ...sediments at a site where C. esculenta is cultivated.•Palmitone concentrations are independent of other lipid inputs from plants.
The Pacific Island ecosystems of Remote Oceania were dramatically transformed following the arrival of humans within the last ∼3000 years, as the new settlers required technological innovations and environmental modifications to maintain their populations. These modifications included the introduction of numerous exotic species, including the important crop Colocasia esculenta Schott (taro) and the development of infrastructure suitable for its cultivation. Archaeological reconstruction of C. esculenta use in the Pacific has been challenging because of the low-specificity of fossil starch granules and its limited pollen production during periods of intense cultivation. Here, we assess a lipid biomarker approach to trace C. esculenta cultivation in the past. We characterized the neutral lipid compositions of leaf samples from common cultivars and widespread indigenous species from the archipelago of Vanuatu by gas chromatography–mass spectrometry (GC–MS). The compound palmitone (hentriacontan-16-one) was a major leaf wax constituent in C. esculenta cultivar samples (mean concentration of 402 ± 63 µg g–1 dry wt) and was only detected in one other species, the ornamental tree Cananga odorata (175 µg g–1 dry wt). The structure of palmitone is favorable for its long-term stability and we demonstrate its preservation potential in a 55 cm sedimentary record from Lake Vesalea on Espiritu Santo, Vanuatu, where C. esculenta is grown today. Palmitone concentrations in this core fluctuated up to 4.1 µg g–1 dry wt. Our results indicate that in appropriate environmental contexts, sedimentary palmitone concentrations could be used to reconstruct C. esculenta cultivation and to provide insights about past horticultural innovations in Remote Oceania.
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