Incorporating Microtopography in a Land Surface Model and Quantifying the Effect on the Carbon Cycle

Graham, Jake D.; Ricciuto, Daniel M.; Glenn, Nancy F.; Hanson, Paul J.

doi:10.1029/2021ms002721

Cited by 4 publications

(4 citation statements)

References 54 publications

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“…It is important to take into account these aspects together with terrain attributes and spatial resolutions for efficacious microtopographic data acquisition. Multiple studies have shown that remote sensing techniques, especially through ALS, TLS, and sUAS can produce high-resolution DEMs and provide fine-scale measurements of microtopography in natural ecosystems [25,26,32,33]. Some studies have used a combination of one or more remote sensing techniques to delineate natural and human features in the environment [72] but multi-platform remote sensing approaches are not yet commonly employed in combination to delineate microtopography, particularly in low relief forested environments.…”

Section: Discussionmentioning

confidence: 99%

“…Recent studies have reported the use of close-range remote sensing technologies to map fine-scale microtopography by using dense and highly accurate elevation data over reasonably large areas [25,[32][33][34][35]. However, this is a recent development, and researchers examining fine-scale processes or distributions have traditionally relied on labor-intensive manual field surveys.…”

Section: Microtopography With Close-range Remote Sensingmentioning

confidence: 99%

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Quantification of Microtopography in Natural Ecosystems Using Close-Range Remote Sensing

et al. 2023

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Microtopography plays an important role in various ecological, hydrologic, and biogeochemical processes. However, quantifying the characteristics of microtopography represents a data-intensive challenge. Over the last decade, high-resolution or close-range remote sensing data and techniques have emerged as powerful tools to quantify microtopography. Traditional field surveys were mostly limited to transects or small plots, using limited sets of observations but with the decrease in the cost of close-range remote sensing technologies and the increase in computing performance, the microtopography even in forested environments can be assessed. The main objective of this article is to provide a systematic framework for microtopographic studies using close-range remote sensing technologies. This is achieved by reviewing the application of close-range remote sensing to capture microtopography and develop microtopographic models in natural ecosystems. Specifically, to achieve the main objectives, we focus on addressing the following questions: (1) What terrain attributes represent microtopography in natural ecosystems? (2) What spatial resolution of terrain attributes is needed to represent the microtopography? (3) What methodologies have been adopted to collect data at selected resolutions? (4) How to assess microtopography? Current research, challenges, and applicability of close-range remote sensing techniques in different terrains are analyzed with an eye to enhancing the use of these new technologies. We highlight the importance of using a high-resolution DEM (less than 1 m2 spatial resolution) to delineate microtopography. Such a high-resolution DEM can be generated using close-range remote sensing techniques. We also illustrate the need to move beyond elevation and include terrain attributes, such as slope, aspect, terrain wetness index, ruggedness, flow accumulation, and flow path, and assess their role in influencing biogeochemical processes such as greenhouse gas emissions, species distribution, and biodiversity. To assess microtopography in terms of physical characteristics, several methods can be adopted, such as threshold-based classification, mechanistically-based delineation, and machine learning-based delineation of microtopography. The microtopographic features can be analyzed based on physical characteristics such as area, volume, depth, and perimeter, or by using landscape metrics to compare the classified microtopographic features. Remote sensing techniques, when used in conjunction with field experiments/data, provide new avenues for researchers in understanding ecological functions such as biodiversity and species distribution, hydrological processes, greenhouse gas emissions, and the environmental factors that influence those parameters. To our knowledge, this article provides a comprehensive and detailed review of microtopography data acquisition and quantification for natural ecosystem studies.

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Section: Discussionmentioning

confidence: 99%

Section: Microtopography With Close-range Remote Sensingmentioning

confidence: 99%

Quantification of Microtopography in Natural Ecosystems Using Close-Range Remote Sensing

et al. 2023

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“…These relationships are reflected in our data establishing correlations between both canopy and relative-elevation with snow depth (figures 4(D) and (E)). Black spruce can reduce soil moisture through transpiration and direct interception of precipitation (Perron et al 2023), and higher relative-elevation locations have reduced soil moisture due to exiting runoff (Engstrom et al 2005, Graham et al 2022. In this way, dense canopy and high relative-elevation keep hummock locations drier (table 1), and therefore, cooler during the warm-season (figures 5(D) and (F)).…”

Section: Hummock and Hollow Location Thaw Was Controlled By Canopy Co...mentioning

confidence: 99%

Canopy cover and microtopography control precipitation-enhanced thaw of ecosystem-protected permafrost

Eklof,

Jones,

Dafflon

et al. 2024

Environ. Res. Lett.

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Northern high-latitudes are projected to get warmer and wetter, which will affect rates of permafrost thaw and mechanisms by which thaw occurs. To better understand the impact of rain, as well as other factors such as snow depth, canopy cover, and microtopography, we instrumented a degrading permafrost plateau in south-central Alaska with high-resolution soil temperature sensors. The site contains ecosystem-protected permafrost, which persists in unfavorable climates due to favorable ecologic conditions. Our study (2020-2022) captured three of the snowiest years and three of the four wettest years since the site was first studied in 2015. Average thaw rates along an across-site transect increased nine-fold from 6±5 cm/year (2015-2020) to 56±12 cm/year (2020-2022). This thaw was not uniform. Hummock locations, residing on topographic high points with relatively dense canopy, experienced only 8±9 cm/year of thaw, on average. Hollows, topographic low points with low canopy cover, and transition locations, which had canopy cover and elevation between hummocks and hollows, thawed 44±6 cm/year and 39±13 cm/year, respectively. Mechanisms of thaw differed between these locations. Hollows had high warm-season soil moisture, which increased thermal conductivity, and deep cold-season snow coverage, which insulated soil. Transition locations thawed primarily due to thermal energy transported through subsurface taliks during individual rain events. Most increases in depth to permafrost occurred below the ~45 cm thickness seasonally frozen layer, and therefore, expanded site taliks.Results highlight the importance of canopy cover and microtopography in controlling soil thermal inputs, the ability of subsurface runoff from individual rain events to trigger warming and thaw, and the acceleration of thaw caused by consecutive wet and snowy years. As northern high-latitudes become warmer and wetter, and weather events become more extreme, the importance of these controls on soil warming and thaw is likely to increase.

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“…Previous research has established that permafrost thaw causes a net loss of soil organic carbon in peatlands due to inadequate surface accumulation rates to compensate for deep organic carbon losses during thawing, which also highlights the importance of spatial heterogeneity in the carbon budget estimation of high-latitude permafrost peatlands [17]. The microtopography of peatland affects soil organic carbon components, soil fauna, enzyme activity, microbial biomass, and microbially regulated greenhouse gas emission processes [18][19][20]. Moreover, microtopography can mediate soil hydrothermal processes and nutrient movements that may further affect microbial community composition and diversity in the soil [21].…”

Section: Introductionmentioning

confidence: 99%

Effects of Microtopography on Soil Microbial Community Structure and Abundance in Permafrost Peatlands

Zhang,

Fu,

et al. 2024

Microorganisms

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Soil microorganisms play crucial roles in the stability of the global carbon pool, particularly in permafrost peatlands that are highly sensitive to climate change. Microtopography is a unique characteristic of peatland ecosystems, but how microtopography affects the microbial community structures and their functions in the soil is only partially known. We characterized the bacterial and fungal community compositions by amplicon sequencing and their abundances via quantitative PCR at different soil depths in three microtopographical positions (hummocks, flats, and hollows) in permafrost peatland of the Greater Xing’an Mountains in China. The results showed that the soil of hummocks displayed a higher microbial diversity compared to hollows. Microtopography exerted a strong influence on bacterial community structure, while both microtopography and soil depth greatly impacted the fungal community structure with variable effects on fungal functional guilds. Soil water content, dissolved organic carbon, total phosphorus, and total nitrogen levels of the soil mostly affected the bacterial and fungal communities. Microtopography generated variations in the soil water content, which was the main driver of the spatial distribution of microbial abundances. This information stressed that the hummock–flat–hollow microtopography of permafrost peatlands creates heterogeneity in soil physicochemical properties and hydrological conditions, thereby influencing soil microbial communities at a microhabitat scale. Our results imply that changes to the water table induced by climate warming inducing permafrost degradation will impact the composition of soil microbes in peatlands and their related biogeochemical functions, eventually providing feedback loops into the global climate system.

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Incorporating Microtopography in a Land Surface Model and Quantifying the Effect on the Carbon Cycle

Cited by 4 publications

References 54 publications

Quantification of Microtopography in Natural Ecosystems Using Close-Range Remote Sensing

Quantification of Microtopography in Natural Ecosystems Using Close-Range Remote Sensing

Canopy cover and microtopography control precipitation-enhanced thaw of ecosystem-protected permafrost

Effects of Microtopography on Soil Microbial Community Structure and Abundance in Permafrost Peatlands

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