A methane sink in the Central American high elevation páramo: Topographic, soil moisture and vegetation effects

Geoderma ◽  
2020 ◽  
Vol 362 ◽  
pp. 114092 ◽  
Author(s):  
Leanne L. Chai ◽  
Guillermo Hernandez-Ramirez ◽  
David S. Hik ◽  
Isabel C. Barrio ◽  
Carol M. Frost ◽  
...  
Keyword(s):  
Soil Moisture ◽  
High Elevation ◽  
Central American ◽  
Vegetation Effects ◽  
Methane Sink

Soil moisture and vegetation effects on the ASCAT backscatter-incidence angle dependence

2021 ◽  
Author(s):  
Isabella Pfeil ◽  
Wolfgang Wagner ◽  
Sebastian Hahn ◽  
Raphael Quast ◽  
Susan Steele-Dunne ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Soil Moisture ◽  
Radiative Transfer ◽  
Incidence Angle ◽  
Transfer Model ◽  
Study Region ◽  
Vegetation Effects ◽  
First Order ◽  
Vegetation Parameters ◽  
Low Incidence

<div> <p>Soil moisture (SM) datasets retrieved from the advanced scatterometer (ASCAT) sensor are well established and widely used for various hydro-meteorological, agricultural, and climate monitoring applications. Besides SM, ASCAT is sensitive to vegetation structure and vegetation water content, enabling the retrieval of vegetation optical depth (VOD; 1). The challenge in the retrieval of SM and vegetation products from ASCAT observations is to separate the two effects. As described by Wagner et al. (2), SM and vegetation affect the relation between backscatter and incidence angle differently.  At high incidence angles, the response from bare soil and thus the sensitivity to SM conditions is significantly weaker than at low incidence angles, leading to decreasing backscatter with increasing incidence angle. The presence of vegetation on the other hand decreases the backscatter dependence on the incidence angle. The dependence of backscatter on the incidence angle can be described by a second-order Taylor polynomial based on a slope and a curvature coefficient. It was found empirically that SM conditions have no significant effect on the steepness of the slope, and that therefore, SM and vegetation effects can be separated using the slope (2).  This is a major assumption in the TU Wien soil moisture retrieval algorithm used in several operational soil moisture products. However, recent findings by Quast et al. (3) using a first-order radiative transfer model for the inversion of soil and vegetation parameters from scatterometer observations indicate that SM may influence the slope, as the SM-induced backscatter increase is more pronounced at low incidence angles. </p> </div><div> <div> <p>The aim of this analysis is to revisit the assumption that SM does not affect the slope of the backscatter incidence angle relations by investigating if short-term variability, observed in ASCAT slope timeseries on top of the seasonal vegetation cycle, is caused by SM. We therefore compare timeseries and anomalies of the ASCAT slope to air temperature, rainfall and SM from the ERA5-Land dataset. We carry out the analysis in a humid continental climate (Austria) and a Mediterranean climate study region (Portugal). First results show significant negative correlations between slope and SM anomalies. However, correlations between temperature and slope anomalies are of a similar magnitude, albeit positive, which may reflect temperature-induced vegetation dynamics. The fact that temperature and SM are strongly correlated with each other complicates the interpretation of the results. Thus, our second approach is to investigate daily slope values and their change between dry and wet days. The results of this study shall help to quantify the uncertainties in ASCAT SM products caused by the potentially inadequate assumption of a SM-independent slope. </p> </div> <div> <p> </p> </div> <div> <p>(1) Vreugdenhil, Mariette, et al. "Analyzing the vegetation parameterization in the TU-Wien ASCAT soil moisture retrieval." IEEE Transactions on Geoscience and Remote Sensing 54.6 (2016): 3513-3531.</p> <p><span>(2) Wagner, Wolfgang, et al. "Monitoring soil moisture over the Canadian Prairies with the ERS scatterometer." IEEE Transactions on Geoscience and Remote Sensing 37.1 (1999): 206-216. </span></p> </div> <div> <p>(3) Quast, Raphael, et al. "A Generic First-Order Radiative Transfer Modelling Approach for the Inversion of Soil and Vegetation Parameters from Scatterometer Observations." Remote Sensing 11.3 (2019): 285.</p> </div> </div>

scholarly journals Validation of GPS-IR Soil Moisture Retrievals: Comparison of Different Algorithms to Remove Vegetation Effects

2016 ◽  
Vol 9 (10) ◽  
pp. 4759-4770 ◽  
Author(s):  
Eric E. Small ◽  
Kristine M. Larson ◽  
Clara C. Chew ◽  
Jingnuo Dong ◽  
Tyson E. Ochsner
Keyword(s):  
Soil Moisture ◽  
Vegetation Effects

scholarly journals Relationship between Vegetation and Environment in an Arid-Hot Valley in Southwestern China

2018 ◽  
Vol 10 (12) ◽  
pp. 4774 ◽  
Author(s):  
Jun Pei ◽  
Wei Yang ◽  
Yangpeng Cai ◽  
Yujun Yi ◽  
Xiaoxiao Li
Keyword(s):  
Soil Moisture ◽  
High Elevation ◽  
Dodonaea Viscosa ◽  
Indigenous Plants ◽  
Multivariate Statistical ◽  
Jinsha River ◽  
Ecological Benefits ◽  
Important Indicator ◽  
Pinus Yunnanensis ◽  
Plant Restoration

The sparse and fragile vegetation in the arid-hot valley is an important indicator of ecosystem health. Understanding the correlation between this vegetation and its environment is vital to the plant restoration. We investigated the differences of soil moisture and fertility in typical vegetation (Dodonaea viscosa and Pinus yunnanensis) under a range of elevations, slopes, and aspects in an arid-hot valley of China’s Jinsha River through field monitoring and multivariate statistical analysis. The soil moisture differed significantly between the dry and rainy seasons, and it was higher at high elevation (>1640 m) and on shade slopes at the end of the dry season. Soil fertility showed little or no variation among the elevations, but was highest at 1380 m. Dodonaea viscosa biomass increased, then decreased, with increasing elevation on the shade slopes, but decreased with increasing elevation on the sunny slopes. On the shade slopes, Pinus yunnanensis biomass was higher at low elevations (1640 m) than it was on sunny slopes, but lower at high elevation (1940 m) on the sunny slopes. We found both elevation and soil moisture were significantly positively correlated with P. yunnanensis biomass and negatively correlated with D. viscosa biomass. Thus, changes in soil moisture as a function of elevation control vegetation restoration in the arid-hot valley. Both species are adaptable indigenous plants with good social and ecological benefits, so these results will allow managers to restore the vegetation more effectively.

Considering combined or separated roughness and vegetation effects in soil moisture retrievals

2017 ◽  
Vol 55 ◽  
pp. 73-86 ◽  
Author(s):  
Marie Parrens ◽  
Jean-Pierre Wigneron ◽  
Philippe Richaume ◽  
Ahmad Al Bitar ◽  
Arnaud Mialon ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Vegetation Effects

scholarly journals Downscaling Climate over Complex Terrain: High Finescale (<1000 m) Spatial Variation of Near-Ground Temperatures in a Montane Forested Landscape (Great Smoky Mountains)*

2009 ◽  
Vol 48 (5) ◽  
pp. 1033-1049 ◽  
Author(s):  
Jason D. Fridley
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Sensor Network ◽  
Spatial Scales ◽  
High Elevation ◽  
Great Smoky Mountains ◽  
Weather Patterns ◽  
Synoptic Weather ◽  
Temperature Regimes ◽  
Smoky Mountains

Abstract Landscape-driven microclimates in mountainous terrain pose significant obstacles to predicting the response of organisms to atmospheric warming, but few if any studies have documented the extent of such finescale variation over large regions. This paper demonstrates that ground-level temperature regimes in Great Smoky Mountains National Park (Tennessee and North Carolina) vary considerably over fine spatial scales and are only partially linked to synoptic weather patterns and environmental lapse rates. A 120-sensor network deployed across two watersheds in 2005–06 exhibited finescale (&lt;1000-m extent) temperature differences of over 2°C for daily minima and over 4°C for daily maxima. Landscape controls over minimum temperatures were associated with finescale patterns of soil moisture content, and maximum temperatures were associated with finescale insolation differences caused by topographic exposure and vegetation cover. By linking the sensor array data to 10 regional weather stations and topographic variables describing site radiation load and moisture content, multilevel spatial models of 30-m resolution were constructed to map daily temperatures across the 2090-km2 park, validated with an independent 50-sensor network. Maps reveal that different landscape positions do not maintain relative differences in temperature regimes across seasons. Near-stream locations are warmer in the winter and cooler in the summer, and sites of low elevation more closely track synoptic weather patterns than do wetter high-elevation sites. This study suggests a strong interplay between near-ground heat and water balances and indicates that the influence of past and future shifts in regional temperatures on the park’s biota may be buffered by soil moisture surfeits from high regional rainfall.

scholarly journals Monitoring soil moisture from middle to high elevation in Switzerland: Set-up and first results from the SOMOMOUNT network

2016 ◽  
Author(s):  
Cécile Pellet ◽  
Christian Hauck
Keyword(s):  
Soil Moisture ◽  
Meteorological Data ◽  
Monitoring Network ◽  
High Elevation ◽  
Time Domain Reflectometry ◽  
Swiss Alps ◽  
Freezing And Thawing ◽  
Altitudinal Distribution ◽  
Mountain Environments ◽  
Stability Of Slopes

Abstract. Besides its important role in the energy and water balance at the soil-atmosphere interface, soil moisture can be a particular important factor in mountain environments since it influences the amount of freezing and thawing in the subsurface and can affect the stability of slopes. In permafrost areas, it is strongly linked to the ground ice content and by this modifies the characteristics and behaviour of periglacial landforms. In spite of its importance, the technical challenges and its strong spatial variability usually prevents soil moisture from being measured operationally at high and/or middle altitudes. This study describes the new Swiss soil moisture monitoring network SOMOMOUNT launched in 2013 consisting in six entirely automated soil moisture stations distributed along an altitudinal gradient between the Jura Mountains and the Swiss Alps, ranging from 1205 m to 3410 m elevation. In addition to the standard instrumentation comprising Frequency Domain Reflectometry (FDR) and Time Domain Reflectometry (TDR) sensors along vertical profiles, soil probes and meteorological data are available at each station. In this contribution we will present a detailed description of the SOMOMOUNT instrumentation and calibration procedures. Additionally, the data collected during the three first years of the project will be discussed in relation to their altitudinal distribution. Clear differences in soil moisture patterns are visible between sites with permanently and seasonally frozen as well as unfrozen ground conditions and can be related to several factors such as the subsurface composition (organic versus mineral), the elevation and the snow cover characteristics.

scholarly journals Environmental Drivers for Cambial Reactivation of Qilian Junipers (Juniperus przewalskii) in a Semi-Arid Region of Northwestern China

Atmosphere ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 232
Author(s):  
Qiao Zeng ◽  
Sergio Rossi ◽  
Bao Yang ◽  
Chun Qin ◽  
Gang Li
Keyword(s):  
Soil Moisture ◽  
Water Availability ◽  
Arid Regions ◽  
High Elevation ◽  
Northwestern China ◽  
Environmental Drivers ◽  
Limiting Factor ◽  
Severe Drought ◽  
Cambial Reactivation ◽  
Semi Arid

Although cambial reactivation is considered to be strongly dependent on temperature, the importance of water availability at the onset of xylogenesis in semi-arid regions still lacks sufficient evidences. In order to explore how environmental factors influence the initiation of cambial activity and wood formation, we monitored weekly cambial phenology in Qilian juniper (Juniperus przewalskii) from a semi-arid high-elevation region of northwestern China. We collected microcores from 12 trees at two elevations during the growing seasons in 2013 and 2014, testing the hypothesis that rainfall limits cambial reactivation in spring. Cambium was reactivated from late April to mid-May, and completed cell division from late July to early August, lasting 70–100 days. Both sites suffered from severe drought from January to April 2013, receiving < 1 mm of rain in April. In contrast, rainfall from January to April 2014 was 5–6 times higher than that in 2013. However, cambial reactivation in 2014 was delayed by 10 days. In spring, soil moisture gradually increased with warming temperatures, reaching 0.15 m3/m3 before the onset of xylogenesis, which may have ensured water availability for tree growth during the rainless period. We were unable to confirm the hypothesis that rainfall is a limiting factor of cambial reactivation. Our results highlight the importance of soil moisture in semi-arid regions, which better describe the environmental conditions that are favorable for cambial reactivation in water-limited ecosystems.

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