Long-term ecological legacies in western Amazonia

M.B.B would like to acknowledge funding from the National Science Foundation (grant nos. EAR1338694 and BCS0926973), the Belmont Forum, and the National Aeronautics and Space Administration (grant no. NNX14AD31G). C.N.H.M would like to acknowledge funding from the European Research Council (ERC 2019 StG 853394). C.N.H.M and M.F.R would like to acknowledge funding from the Netherlands Organisation for Scientific Research (ALWOP.322). S.N.H, M.P, and Jo.V performed this research as a part of the BSc research program of the Institute for Biodiversity and Ecosystem Dynamics at the University of Amsterdam.1. Modifications of Amazonian forests by pre‐Columbian peoples are thought to have left ecological legacies that have persisted to the modern day. Most Amazonian palaeoecological records do not, however, provide the required temporal resolution to document the nuanced changes of pre‐Columbian disturbance or post‐disturbance succession and recovery, making it difficult to detect any direct, or indirect, ecological legacies on tree species. 2. Here, we investigate the fossil pollen, phytolith and charcoal history of Lake Kumpaka, Ecuador, during the last 2,415 years in c. 3–50 year time intervals to assess ecological legacies resulting from pre‐Columbian forest modification, disturbance, cultivation and fire usage. 3. Two cycles of pre‐Columbian cultivation (one including slash‐and‐burn cultivation, the other including slash‐and‐mulch cultivation) were documented in the record around 2150–1430 cal. year BP and 1250–680 cal. year BP, with following post‐disturbance succession dynamics. Modern disturbance was documented after c. 10 cal. year BP. The modern disturbance produced a plant composition unlike those of the two past disturbances, as fire frequencies reached their peak in the 2,415‐year record. The disturbance periods varied in intensity and duration, while the overturn of taxa following a disturbance lasted for hundreds of years. The recovery periods following pre‐Columbian disturbance shared some similar patterns of early succession, but the longer‐term recovery patterns differed. 4. Synthesis. The trajectories of change after a cessation of cultivation can be anticipated to differ depending on the intensity, scale, duration and manner of the past disturbance. In the Kumpaka record, no evidence of persistent enrichment or depletion of intentionally altered taxa (i.e. direct legacy effects) was found but indirect legacy effects, however, were documented and have persisted to the modern day. These findings highlight the strengths of using empirical data to reconstruct past change rather than relying solely on modern plant populations to infer past human management and ecological legacies, and challenge some of the current hypotheses involving the persistence of pre‐Columbian legacies on modern plant populations.Publisher PDFPeer reviewe

Columbus’ footprint in Hispaniola:A paleoenvironmental record of indigenous and colonial impacts on the landscape of the central Cibao Valley, northern Dominican Republic

The 1100-year sedimentary record of Laguna Biajaca reveals human-driven landscape changes in the central Cibao Valley, Dominican Republic, Hispaniola. This sediment-filled cutoff meander is located in close proximity to pre-Colonial archaeological sites and a Colonial urban hub. It provided a nutrient-rich floodable locus for agricultural activities for indigenous communities and for the first introduction of Old World crops and cattle in the Americas. Integration of paleoecological proxies revealed the formation of a clear-water body surrounded by a palm-rich forested landscape around 1100 cal yr BP. Changes in the drainage system were linked to human-driven deforestation, which also changed the composition of the vegetation and fungal communities around the site between AD 1150 and 1500 (800 and 700 cal yr BP). Pre-Colonial modifications of the landscape were primarily the result of fire-use and small-scale clearings. Crop cultivation developed between AD 1250 and 1450 (700–500 cal yr BP). Within decades after Columbus’ arrival in Hispaniola in AD 1492, the first impacts of European colonization included the abandonment of indigenous sites and the introduction of Old World domesticated animals. During the 15th and 16th centuries the area underwent intensive land-clearing that allowed for larger scale crop cultivation. An increase of aquatic vegetation points to sediment-filling around AD 1700 (250 cal yr BP). At that time, cattle breeding expanded and rapidly provoked eutrophication while, concurrently, monocultures became regionally established. This paper provides a framework of past environmental dynamics and offers an opportunity to place archaeological findings in a context of natural and anthropogenic change

Data from: Reconstructing past fire temperatures from ancient charcoal material

Charcoal chemistry spectra generated using Fourier Transformed Infrared Spectroscopy (FTIR) for modern reference and ancient charcoal. For further details see the associated publication: Gosling, W.D., Cornelissen, H.L. & McMichael, C.N.H. (2019) Reconstructing past fire temperatures from ancient charcoal material. Palaeogeography, Palaeoclimatology, Palaeoecology. https://doi.org/10.1016/j.palaeo.2019.01.02

Data from: Holocene variability of an Amazonian hyperdominant

Little is known regarding the long-term stability or instability of Amazonian plant communities. We assessed whether the most abundant species, hyperdominants, may have risen to prominence at the Pleistocene–Holocene transition, following subsequent changes in moisture regimes, or as a result of human activity later in the Holocene. The fossil pollen history of the commonest western Amazonian tree, Iriartea deltoidea (hereafter Iriartea), is investigated using fossil pollen data from 13 lakes. Iriartea is a monospecific genus with diagnostic pollen. It is also considered a ‘useful’ plant, and its abundance could have been enriched by human action. Iriartea pollen was found to have increased in abundance in the last 3000 years, but did not show a consistent relationship with human activity. The suggestion that the hyperdominants in modern Amazonian forests are a legacy of pre-Columbian people is unsupported. The abundance of Iriartea pollen is related to increasing precipitation, not human activity over the last 3000 years. This member of the hyperdominant category of Amazonian trees has only recently acquired this status. Synthesis. Our findings are consistent with the observation that communities in complex systems are ephemeral. The populations of even the most abundant species can change over a few tens of generations. The relative abundance of tree species, even in relatively stable systems such as those of Amazonian floodplains, changes on ecological not evolutionary timescales

On the scaling and standardization of charcoal data in paleofire reconstructions

Understanding the biogeography of past and present fire events is particularly important in tropical forest ecosystems, where fire rarely occurs in the absence of human ignition. Open science databases have facilitated comprehensive and synthetic analyses of past fire activity, but charcoal datasets must be standardized (scaled) because of variations in measurement strategy, sediment type, and catchment size. Here, we: i) assess how commonly used metrics of charcoal scaling perform on datasets from tropical forests; ii) introduce a new method called proportional relative scaling, which down-weights rare and infrequent fire; and iii) compare the approaches using charcoal data from four lakes in the Peruvian Amazon. We found that Z-score transformation and relative scaling (existing methods) distorted the structure of the charcoal peaks within the record, inflating the variation in small-scale peaks and minimizing the effect of large peaks. Proportional relative scaling maintained the structure of the original non-scaled data and contained zero values for the absence of fire. Proportional relative scaling provides an alternative scaling approach when the absence of fire is central to the aims of the research or when charcoal is infrequent and occurs in low abundances

Data from: Preliminary evidence for green, brown and black worlds in tropical western Africa during the Middle and Late Pleistocene

Palaeoecological data (Poaceae pollen, Poaceae phytoliths, tree phytoliths, sporomiella, and micro-charcoal) obtained from Lake Bosumtwi (core BOS04-5B). For further details see the associated publication: Gosling, W.D., McMichael, C.N.H., Groenewoud, Z., Roding, E., Miller, C.S. and Julier, A.C.M. (2021) Preliminary evidence for green, brown and black worlds in tropical western Africa during the Middle and Late Pleistocene, Palaeoecology of Africa 35

Palaeoecological sites used in the analysis from Early to Mid-Holocene human activity exerted gradual influences on Amazonian forest vegetation

Metadata for all palaeoecological sites used in the analysi

Archaeological and soil sites from Early to Mid-Holocene human activity exerted gradual influences on Amazonian forest vegetation

List of archaeological and soil charcoal sites used in the manuscrip

Data from: Scarce fire activity in the north and north-western Amazonian forests during the last 10,000 years

Data related to: William D. Gosling, S. Yoshi Maezumi, Britte M. Heijink, Majoi N. Nascimento, Marco F. Raczka, Masha T. van der Sande, Mark B. Bush, Crystal N.H. McMichael (2021) Scarce fire activity in the north and north-western Amazonian forests during the last 10,000 years. Plant Ecology & Diversity. DOI: https://doi.org/10.1080/17550874.2021.200804

Useful species list from Early to Mid-Holocene human activity exerted gradual influences on Amazonian forest vegetation

List of useful species used in the analysi