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1. Remote Sensing Reveals Lasting Legacies of Land-Use by Small-Scale Foraging Communities in the Southwestern Indian Ocean

   https://doi.org/10.3389/fevo.2021.689399  

   Davis, Dylan S.; Douglass, Kristina (September 2021, Frontiers in ecology and evolution)

   Clark, G. (Ed.)

   Archaeologists interested in the evolution of anthropogenic landscapes have productively adopted Niche Construction Theory (NCT), in order to assess long-term legacies of human-environment interactions. Applications of NCT have especially been used to elucidate co-evolutionary dynamics in agricultural and pastoral systems. Meanwhile, foraging and/or highly mobile small-scale communities, often thought of as less intensive in terms of land-use than agropastoral economies, have received less theoretical and analytical attention from a landscape perspective. Here we address this lacuna by contributing a novel remote sensing approach for investigating legacies of human-environment interaction on landscapes that have a long history of co-evolution with highly mobile foraging communities. Our study is centered on coastal southwest Madagascar, a region inhabited by foraging and fishing communities for close to two millennia. Despite significant environmental changes in southwest Madagascar’s environment following human settlement, including a wave of faunal extinctions, little is known about the scale, pace and nature of anthropogenic landscape modification. Archaeological deposits in this area generally bear ephemeral traces of past human activity and do not exhibit readily visible signatures of intensive land-use and landscape modification (e.g., agricultural modifications, monumental architecture, etc.). In this paper we use high-resolution satellite imagery and vegetative indices to reveal a legacy of human-landscape co-evolution by comparing the characteristics – vegetative productivity and geochemical properties – of archaeological sites to those of locations with no documented archaeological materials. Then, we use a random forest (RF) algorithm and spatial statistics to quantify the extent of archaeological activity and use this analysis to contextualize modern-day human-environment dynamics. Our results demonstrate that coastal foraging communities in southwest Madagascar over the past 1,000 years have extensively altered the landscape. Our study thus expands the temporal and spatial scales at which we can evaluate human-environment dynamics on Madagascar, providing new opportunities to study early periods of the island’s human history when mobile foraging communities were the dominant drivers of landscape change. 

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2. An Integrated Multi-Source Dataset for Measuring Settlement Evolution in the United States from 1810 to 2020

   https://doi.org/10.1038/s41597-024-03081-x  

   Ahn, Yoonjung; Leyk, Stefan; Uhl, Johannes H.; McShane, Caitlin M. (March 2024, Scientific Data)

   Abstract Understanding changes in the built environment is vital for sustainable urban development and disaster preparedness. Recent years have seen the emergence of a variety of global, continent-level, and nation-wide datasets related to the current state and the evolution of the built environment, human settlements or building stocks. However, such datasets may face limitations like incomplete coverage, sparse building information, coarse resolution, and limited timeframes. This study addresses these challenges by integrating three spatial datasets to create an extensive, attribute-rich sequence of settlement layers spanning 200 years for the contiguous U.S. This integration process involves complex data processing, merging property-level real estate, parcel, and remote sensing-based building footprint data, and creating gridded multi-temporal settlement layers. This effort unveils the latest edition (Version 2) of the Historical Settlement Data Compilation for the U.S. (HISDAC-US), which includes the latest land use and structural information as of the year 2021. It enables detailed research on urban form and structure, helps assess and map the built environment’s risk to natural hazards, assists in population modeling, supports land use analysis, and aids health studies. 

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3. A Holocene history of climate, fire, landscape evolution, and human activity in northeastern Iceland

   https://doi.org/10.5194/cp-20-1087-2024  

   Ardenghi, Nicolò; Harning, David J.; Raberg, Jonathan H.; Holman, Brooke R.; Thordarson, Thorvaldur; Geirsdóttir, Áslaug; Miller, Gifford H.; Sepúlveda, Julio (January 2024, Climate of the Past)

   Abstract. Paleoclimate reconstructions across Iceland provide a template for past changes in climate across the northern North Atlantic, a crucial region due to its position relative to the global northward heat transport system and its vulnerability to climate change. The roles of orbitally driven summer cooling, volcanism, and human impact as triggers of local environmental changes in the Holocene of Iceland remain debated. While there are indications that human impact may have reduced environmental resilience during late Holocene summer cooling, it is still difficult to resolve to what extent human and natural factors affected Iceland's late Holocene landscape instability. Here, we present a continuous Holocene fire record of northeastern Iceland from proxies archived in Stóra Viðarvatn sediment. We use pyrogenic polycyclic aromatic hydrocarbons (pyroPAHs) to trace shifts in fire regimes, paired with continuous biomarker and bulk geochemical records of soil erosion, lake productivity, and human presence. The molecular composition of pyroPAHs and a wind pattern reconstruction indicate a naturally driven fire signal that is mostly regional. Generally low fire frequency during most of the Holocene significantly increased at 3 ka and again after 1.5 ka BP before known human settlement in Iceland. We propose that shifts in vegetation type caused by cooling summers over the past 3 kyr, in addition to changes in atmospheric circulation, such as shifts in North Atlantic Oscillation (NAO) regime, led to increased aridity and biomass flammability. Our results show no evidence of faecal biomarkers associated with human activity during or after human colonisation in the 9th century CE. Instead, faecal biomarkers follow the pattern described by erosional proxies, pointing toward a negligible human presence and/or a diluted signal in the lake's catchment. However, low post-colonisation levels of pyroPAHs, in contrast to an increasing flux of erosional bulk proxies, suggest that farming and animal husbandry may have suppressed fire frequency by reducing the spread and flammability of fire-prone vegetation (e.g. heathlands). Overall, our results describe a fire frequency heavily influenced by long-term changes in climate through the Holocene. They also suggest that human colonisation had contrasting effects on the local environment by lowering its resilience to soil erosion while increasing its resilience to fire. 

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4. Marine shellfish exploitation as a means of reducing vulnerability to resource uncertainty in southern coastal Peru (200 BCE–150 CE)

   https://doi.org/10.1177/09596836221122633  

   Weinberg, Camille; Osborn, Jo; Espino Huaman, Richard (December 2022, The Holocene)

   The effects of El Niño Southern Oscillation (ENSO) are notoriously hazardous for human populations of the hyperarid Peruvian coast. Yet, ENSO climate fluctuations are fundamental to the ecology of desert plant and animal resources that have been incorporated into human subsistence economies for millennia. We examine marine shellfish exploitation among early complex societies in southern coastal Peru at the end of the first millenium BCE to better understand the subsistence vulnerability of communities in arid environments with variable resource availability and productivity. We analyze new shellfish data from Jahuay, a shoreline fishing settlement in the Topará Quebrada occupied amidst new regional social hierarchies and intensifying inner-valley agriculture. We compare mollusk taxonomic diversity and taxa rank order with published assemblages from four near-contemporaneous sites to assess local and regional trends in resource exploitation. At Jahuay, a unique focus on foraging plentiful Donax obesulus clams resistant to ENSO effects may reflect a local buffering strategy to ensure a resource supply through interannual and decadal climate oscillations. Our comparative results suggest regional reliance on intertidal resource patches, especially rocky habitats, for consumable shellfish. The relative convenience of gathering sessile intertidal taxa that form dense settlements may partly explain their regional popularity. The potential to dry and exchange mollusk meat as a protein source likely enhanced diet diversification while supporting economic and social relationships between communities. Overall, our findings imply that mollusks and intertidal foraging landscapes were important within a broad-spectrum subsistence strategy suited to maintaining and coordinating food availability in a dynamic environment. 

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5. The underground network: facilitation in soil bacteria

   https://doi.org/10.1111/oik.10299  

   Jorna, Jesse; Adams, Byron J; Aanderud, Zachary T; Frandsen, Paul B; Takacs‐Vesbach, Cristina; Kéfi, Sonia (August 2024, Oikos)

   Our understanding of the fundamental role that soil bacteria play in the structure and functioning of Earth's ecosystems is ever expanding, but insight into the nature of interactions within these bacterial communities remains rudimentary. Bacterial facilitation may enhance the establishment, growth, and succession of eukaryotic biota, elevating the complexity and diversity of the entire soil community and thereby modulating multiple ecosystem functions. Global climate change often alters soil bacterial community composition, which, in turn, impacts other dependent biota. However, the impact of climate change on facilitation within bacterial communities remains poorly understood even though it may have important cascading consequences for entire ecosystems. The wealth of metagenomic data currently being generated gives community ecologists the ability to investigate bacterial facilitation in the natural world and how it affects ecological systems responses to climate change. Here, we review current evidence demonstrating the importance of facilitation in promoting emergent properties such as community diversity, ecosystem functioning, and resilience to climate change in soil bacterial communities. We show that a synthesis is currently missing between the abundant data, newly developed models and a coherent ecological framework that addresses these emergent properties. We highlight that including phylogenetic information, the physicochemical environment, and species‐specific ecologies can improve our ability to infer interactions in natural soil communities. Following these recommendations, studies on bacterial facilitation will be an important piece of the puzzle to understand the consequences of global change on ecological communities and a model to advance our understanding of facilitation in complex communities more generally. 

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