Mapping Relict Charcoal Hearths in New England Using Deep Convolutional Neural Networks and LiDAR Data

Advanced deep learning methods combined with regional, open access, airborne Light Detection and Ranging (LiDAR) data have great potential to study the spatial extent of historic land use features preserved under the forest canopy throughout New England, a region in the northeastern United States. Mapping anthropogenic features plays a key role in understanding historic land use dynamics during the 17th to early 20th centuries, however previous studies have primarily used manual or semi-automated digitization methods, which are time consuming for broad-scale mapping. This study applies fully-automated deep convolutional neural networks (i.e., U-Net) with LiDAR derivatives to identify relict charcoal hearths (RCHs), a type of historical land use feature. Results show that slope, hillshade, and Visualization for Archaeological Topography (VAT) rasters work well in six localized test regions (spatial scale: <1.5 km2, best F1 score: 95.5%), but also at broader extents at the town level (spatial scale: 493 km2, best F1 score: 86%). The model performed best in areas with deciduous forest and high slope terrain (e.g., >15 degrees) (F1 score: 86.8%) compared to coniferous forest and low slope terrain (e.g., <15 degrees) (F1 score: 70.1%). Overall, our results contribute to current methodological discussions regarding automated extraction of historical cultural features using deep learning and LiDAR.

When Computers Dream of Charcoal

This research employs machine learning (Mask Region-Based Convolutional Neural Networks [Mask R-CNN]) and cluster analysis (Density-based spatial clustering of applications with noise [DBSCAN]) to identify more than 20,000 relict charcoal hearths (RCHs) organized in large “fields” within and around State Game Lands (SGLs) in Pennsylvania. This research has two important threads that we hope will advance the archaeological study of landscapes. The first is the significant historical impact of charcoal production, a poorly understood industry of the late eighteenth to early twentieth century, on the historic and present landscape of the United States. Although this research focuses on charcoal production in Pennsylvania, it has broad application for both identifying and contextualizing historical charcoal production throughout the world and for better understanding modern charcoal production. The second thread is the use of open data, open source, and open access tools to conduct this analysis, as well as the open publication of the resultant data. Not only does this research demonstrate the significance of open access tools and data but the open publication of our code as well as our data allow others to replicate our work, to tweak our code and protocols for their own work, and reuse our results.

Relic charcoal hearths geomorphology and hydrology in mid-Appalachian region of Pennsylvania

&lt;p&gt;Throughout the northeastern United States and Europe, relic charcoal hearths (RCHs) are more regularly being discovered in proximity to furnaces used for iron or quick-lime production; charcoal was used as a primary fuel source in the furnaces.&amp;#160; RCHs have been found across parts of Europe and Connecticut, USA in different hillslope positions, on vary degrees of slope and aspect, all of which can be a factor affecting the shape of the RCH.&amp;#160; Their usage for charcoal production varied with the time period, furnaces were in operation with some hearths being used once and older ones (such as in Europe) being used multiple times. RCHs across the northcentral Appalachians, USA have been minimally investigated, thus determining where they occur on the landscape, their shape, and their morphologic positions will be useful in discerning their effect on surface hydrology and soil development. Our study focuses on developing a repeatable process for: finding RCHs and quantifying how RCHs may alter surface hydrology. &amp;#160;&lt;/p&gt;&lt;p&gt;We used a combination of processed LiDAR data to create hillshades, and slope gradients to visualize RCHs.&amp;#160; A total of 6,758 hearths have been digitized across three study areas that reflect different historical time periods of construction and environments. We hypothesize that the construction of RCHs can alter the surface hydrology of their surrounding environments. To fully quantify the landscape-level effects of RCHs, a subset of the total was created to fully digitize the RCHs&amp;#8217; area.&amp;#160; The RCH was broken into their rim and platform components.&amp;#160; A topographic wetness index (TWI), and SAGA wetness index (SWI) was created for two study areas in order to quantify surface hydrology effects.&amp;#160; We found that RCH platforms have a significantly higher TWI and SWI than the rim counterparts indicating that the platform is wetter than the RCH outer rims.&amp;#160; Geomorphic position was found to not effect wetness. &amp;#160;Using field measured volumetric water content, we found that as distance from the center of the hearth increases, the drier the soil becomes. Using a combination of GIS flow path analysis, and RCH geometry, standardized ellipses using the axis of local RCHs and the mean area of the total RCHs were created to understand the upslope (control) and downslope (experiment) effects of hearths on the surface hydrology.&amp;#160; Preliminary analysis indicates that downslope positions from RCHs are drier than upslope positions and that there is a significant difference in the relationship between slope position and distance from an RCH and the corresponding TWI and SWI values. Future research will address the effect of slope position and distance to quantify the effect of RHCs on surface hydrology. Furthermore, the soil chemical changes from RCH creation and the increase moisture may increase the habitat for rare species of both plants and animals that otherwise would not be present.&amp;#160; Understanding the extent of the impact human activity can have on various ecosystems can help forest managers, conservationists, pedologists, and climatologists better adapt their management or research pursuits within a specific environment to prepare for future changes, natural or anthropogenic.&lt;/p&gt;

Fingerprints from past charcoal burning - lessons learned and future perspective studying Relict Charcoal Hearths (RCH)

&lt;p class=&quot;IOPAbsText&quot;&gt;&lt;span lang=&quot;EN-GB&quot;&gt;Digital Elevation Models (DEMs) recorded by LiDAR are now available for large areas, providing an opportunity to map small landforms for the first time in high resolution and over larger areas. &amp;#160;The majority of these small earth surface structures is of anthropogenic origin, and their formation is often ancient. The newly visible microrelief can therefore reflect the imprints of centuries or millennia of past land uses. Among the anthropogenic structures identified in the new high-resolution DEMs, Relict Charcoal Hearths (RCHs) are particularly widespread and abundant. RCHs are remains of past charcoal burning and mainly found in pre-industrial mining areas of Europe and North America. They normally have a relative height of fewer than 50 centimetres on flat terrain and a horizontal dimension ranging from about 5-30 metres. Despite the small spatial dimensions, RCHs can reach significant land coverage due to their enormous numbers. Recent LiDAR data show that a remarkable area of our landscape has this human fingerprint from the past. We therefore need to ask about its effect on soil landscapes and ecosystems in general. The growing relevance of RCHs is also noticeable in the rising number of RCH case studies that have been conducted. This study reviews the state of knowledge about RCHs mainly by addressing three coupled legacies of historic charcoal burning: the geomorphological, the pedological, and the ecological legacy. We are going to present recent findings on these three legacies.&lt;/span&gt;&lt;/p&gt;