Locating drainage tiles at a wetland restoration site within the Oak Openings region of Ohio, United States using UAV and land based geophysical techniques

Drainage tiles were used to drain wetlands in the midwestern United States to convert them into farmlands. With decades of farm operations, utility maps showing tiles’ locations are now mostly innaccurate or simply do not exist. However, knowledge of the location of tile networks is needed to effectively restore these farmlands to their original wetlands conditions. With many fields spanning several hectares, efficiently locating drainage tiles at large farmfields can be problematic. Drainage tiles create variations in soil physical properties including moisture content, surface temperature and dielectric permeativity within and around the pipes which can be sensed by geophysical methods. Our study assesses the application of electromagnetic radiation via visible and thermal infrared imaging using an unmanned aerial vehicle and ground penetrating radar (GPR) to locate drainage tiles at large farmfield scale. The study was conducted at the Sandhill Crane wetland, a 1.1 km2 old agricultural field located in Swanton, Ohio. A UAV equiped with visible and thermal infrared cameras acquired imagery on a regular grid and about 100 GPR lines were measured using a 250 MHz radar system. Both visible and thermal infrared images identified the drainage tiles and their orientations. GPR profiles reveal the drainage tiles mostly in a parallel East-West direction. By using a UTV to pull the GPR system, we efficiently collected data along long profiles covering the entire site. The delineated tile network will improve management of the anthropogenically altered hydrology at the site as it is being restored into its original wetland conditions.

Causal Analysis of Ecological Impairment in Land Ecosystem on a Regional Scale: Applied to a Mining City Daye, China

We adopted a weight of evidence approach to establish a causal analysis of an impaired land ecosystem on a regional scale; namely, Daye, a traditional mining city in China. Working processes, including problem statements, a list of candidate causes, and a conceptual model were developed to represent a causal hypothesis for describing land degradation. Causal criteria were applied to integrate multiple lines of evidence. Then, various pieces of evidence were scored to either strengthen or weaken our causal assumptions. Results showed that habitat alteration, heavy metal accumulation, organic pollutants, water eutrophication, and nutrient runoff were the probable causes of land ecosystem impairment in Daye. Meanwhile, noxious gas, toxicants, altered underground runoff, atmospheric deposition, and acid rain were identified as possible causes. The most unlikely causes were altered hydrology, altered earth surface runoff, and soil erosion. Soil salinization, soluble inorganic salts, biological species invasion, and pathogens were deferred as delayed causes due to lack of adequate information. The causal analysis approach was applied to identify the primary causes of land degradation and implement accurate protective measures in an impaired land ecosystem.

Methanogenic archaea in peatlands

ABSTRACT Methane emission feedbacks in wetlands are predicted to influence global climate under climate change and other anthropogenic stressors. Herein, we review the taxonomy and physiological ecology of the microorganisms responsible for methane production in peatlands. Common in peat soils are five of the eight described orders of methanogens spanning three phyla (Euryarchaeota, Halobacterota and Thermoplasmatota). The phylogenetic affiliation of sequences found in peat suggest that members of the thus-far-uncultivated group Candidatus Bathyarchaeota (representing a fourth phylum) may be involved in methane cycling, either anaerobic oxidation of methane and/or methanogenesis, as at least a few organisms within this group contain the essential gene, mcrA, according to metagenomic data. Methanogens in peatlands are notoriously challenging to enrich and isolate; thus, much remains unknown about their physiology and how methanogen communities will respond to environmental changes. Consistent patterns of changes in methanogen communities have been reported across studies in permafrost peatland thaw where the resulting degraded feature is thermokarst. However much remains to be understood regarding methanogen community feedbacks to altered hydrology and warming in other contexts, enhanced atmospheric pollution (N, S and metals) loading and direct anthropogenic disturbances to peatlands like drainage, horticultural peat extraction, forestry and agriculture, as well as post-disturbance reclamation.

A Limited Rapid Assessment of Forest Regeneration in 24 Cypress and Tupelo Bottomland Swamps Following Clearcutting and Shovel Logging in the Coastal Plain of North Carolina

A rapid regeneration survey within twenty-four deepwater swamps between stand ages 2 and 14 years in the North Carolina coastal plain was conducted by using a narrow rectangular inventory technique (“strip cruise”). Inventoried tracts predominantly contained cypress (Taxodium distichum) and tupelo (Nyssa species) before being harvested via clearcutting methods. Single transects on each tract began at coordinates located in the interior of the harvest areas in locations representing general tract conditions. Each transect was perpendicular to the flow of the major stream drainage associated with the harvest area. Counts and measures of dead and live stumps and seed-sourced regeneration were recorded. About 52 percent of desirable timber species stumps tallied had coppice growth. However, coppice alone was not sufficient on any tract to exceed 1112 trees ha−1. Seventy-one percent of tracts had stocking levels (coppice and seed source) at least 1112 trees ha−1 of desirable timber species or black willow (Salix nigra). Across 24 tracts, 42 percent regenerated cypress and/or tupelo to levels exceeding 1112, trees ha−1. This assessment revealed that forest regeneration success was limited on sites with altered hydrology, rampant invasive species, and/or lack of seed source. In some cases, active forest management may improve the regeneration cohort. Overall, shovel logging methods that were used on evaluated sites appear to be compatible with adequate regeneration of desirable timber species if the proper conditions exist. Additionally, we assessed species’ composition within a harvested stand measured at age eight years (a previous study) and age 68 years (measured for this study), for a comparison perspective. Results revealed a species composition change from willow at age eight years to a mixed stand of desirable timber species at age 68 years. This finding supports other studies that have recorded the successional pattern of pioneering willow shifting to desirable timber species as willow stagnates and diminishes in abundance due to natural mortality.

Low watershed hydrological and erosion response after fire can be explained by connectivity

<p>Mediterranean regions have always been affected by wildfires. However, no studies investigating post-fire hydrological responses and erosion at the watershed scale (~>10 km2) were conducted in Mediterranean. In this study, the discharge and sediment measurements at the outlet of a Mediterranean watershed were observed to test changes in hydrological responses and sediment loads before and after the fire. Besides, aid by the PCA analysis and analysis of connectivity patterns and changes using the index of connectivity (IC), we analyze the hydrological responses and erosion to a wildfire at the watershed scale. Although most of vegetation was removed after the wildfire, it did not, overall, lead to a significant increase in hydrological responses and sediment loads at the watershed scale. Our results can be explained by three major factors. Firstly, much lower rainfall the first two hydrological years after the fire occurred in our watershed. Secondly, as a result of the scale dependency of hydrological and erosion processes, fire-enhanced overland flow and sediment transport occurred locally on hillslope with high burn severity but did not (yet) reach the outlet. Finally, and arguably, most importantly, connectivity in our study area is relatively low and, although it increases after the fire, it remains generally low. Even though post-wildfire connectivity in our watershed increased by 20%, this increase in connectivity was mainly located in the upstream-most part of this catchment, with much less increased connectivity in the downstream areas, which are closer to the catchment outlet. We concluded that the fire consumed vegetation and altered hydrology and erosion processes but didn’t significantly influence downstream water quantity and quality. Connectivity linked to burn severity was suitable for evaluating the effect of wildfire on hydrological responses and erosion. Moreover, this method also appears to be reasonable in assessing and mitigating post-fire water contamination risk.</p>