scholarly journals Small scale variability in soil moisture drives infection of vulnerable juniper populations by invasive forest pathogen

2020 ◽  
Vol 473 ◽  
pp. 118324 ◽  
Author(s):  
Flora Donald ◽  
Sarah Green ◽  
Kate Searle ◽  
Nik J. Cunniffe ◽  
Bethan V. Purse
Keyword(s):  
Soil Moisture ◽  
Small Scale ◽  
Forest Pathogen

Net precipitation assessment in a grassland and soil moisture response at plot scale in a temperate climate

2021 ◽  
Author(s):  
Gökben Demir ◽  
Johanna Clara Metzger ◽  
Janett Filipzik ◽  
Christine Fischer ◽  
Beate Michalzik ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Spatial Variation ◽  
Canopy Structure ◽  
Sampling Period ◽  
Temperate Climate ◽  
Small Scale ◽  
Spatial Effects ◽  
Mixed Effect ◽  
Canopy Development ◽  
Canopy Effect

<div> <p>Evidence on spatial variation of net precipitation in grasslands is scarce. Challenges arise due to a small-scale canopy structure of grasslands.</p> <p>In this study, we designed and tested a new in-situ measurement device (interception grid) to assess net precipitation in grasslands. The collector allows the natural development of the canopy. We tested the device both in the lab for splash loss and in the field to test its capacity to assess net precipitation. In the field, we installed 25 collectors on a grassland within the Hainich Critical Zone Exploratory (Thuringia, Germany), 23 of which were paired with soil moisture sensors. We conducted weekly measurements gross and net precipitation (above and below the canopy), along with grass height in 2019 (March-August) and 2020 (January -February). We categorized the data into two groups (‘covered,’ ‘uncovered’), accounting for canopy development.</p> <p>In the lab, we found that the drop size strongly affects splash loss. Drops of ca. 2 mm, created more than 16% splash loss, decreasing to less than 3% for drops <1.5 mm. Drop sizes <1.75 mm during the sampling period (2019) suggest low to intermediate splash loss in the field, further decreased in the covered period as the canopy contact slows down the drops. Grid measurements corrected with estimated splash loss during the uncovered period agreed well with gross precipitation. Using linear mixed effect models, we found that wind speed and grass height significantly affected the grid measurements of covered periods. Therefore, grids were able to capture net precipitation variation due to grass development. These steps encouraged us to examine the canopy effect in the soil moisture response to rainfall.</p> <p>Soil moisture response over the entire period was not related to the spatial variation of net precipitation. However, for the drier period (June-August 2019), when the spatial variation in soil moisture is higher, and the overall response to rain events stronger, net precipitation slightly affected soil moisture response. LMEM analysis to estimate factors on soil moisture response showed that grass height, net precipitation are significant predictors. Yet, there is no remarkable difference between using net precipitation and gross precipitation as potential drivers for soil moisture response, indicating that the spatial effects are comparatively small. Overall, our findings suggest that the grids are cable to catch canopy effects on the precipitation, while the effect of wind on under-catch still needs to be investigated further.</p> </div>

scholarly journals Implications of CO<sub>2</sub> pooling on δ<sup>13</sup>C of ecosystem respiration and leaves in Amazonian forest

2008 ◽  
Vol 5 (3) ◽  
pp. 779-795 ◽  
Author(s):  
A. C. de Araújo ◽  
J. P. H. B. Ometto ◽  
A. J. Dolman ◽  
B. Kruijt ◽  
M. J. Waterloo ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Carbon Isotope ◽  
Isotope Ratio ◽  
Ecosystem Respiration ◽  
Nitrogen Concentration ◽  
Carbon Isotope Ratio ◽  
Dry Season ◽  
Small Scale ◽  
Supporting Evidence ◽  
Co2 Efflux

Abstract. The carbon isotope of a leaf (δ13Cleaf) is generally more negative in riparian zones than in areas with low soil moisture content or rainfall input. In Central Amazonia, the small-scale topography is composed of plateaus and valleys, with plateaus generally having a lower soil moisture status than the valley edges in the dry season. Yet in the dry season, the nocturnal accumulation of CO2 is higher in the valleys than on the plateaus. Samples of sunlit leaves and atmospheric air were collected along a topographical gradient in the dry season to test whether the δ13Cleaf of sunlit leaves and the carbon isotope ratio of ecosystem respired CO2 (δ13CReco) may be more negative in the valley than those on the plateau. The δ13Cleaf was significantly more negative in the valley than on the plateau. Factors considered to be driving the observed variability in δ13Cleaf were: leaf nitrogen concentration, leaf mass per unit area (LMA), soil moisture availability, more negative carbon isotope ratio of atmospheric CO2 (δ13Ca) in the valleys during daytime hours, and leaf discrimination (Δleaf). The observed pattern of δ13Cleaf might suggest that water-use efficiency (WUE) is higher on the plateaus than in the valleys. However, there was no full supporting evidence for this because it remains unclear how much of the difference in δ13Cleaf was driven by physiology or &amp;delta13Ca. The δ13CReco was more negative in the valleys than on the plateaus on some nights, whereas in others it was not. It is likely that lateral drainage of CO2 enriched in 13C from upslope areas might have happened when the nights were less stable. Biotic factors such as soil CO2 efflux (Rsoil) and the responses of plants to environmental variables such as vapor pressure deficit (D) may also play a role. The preferential pooling of CO2 in the low-lying areas of this landscape may confound the interpretation of δ13Cleaf and δ13CReco.

scholarly journals Implications of CO<sub>2</sub> pooling on δ<sup>13</sup>C of ecosystem respiration and leaves in Amazonian forest

2007 ◽  
Vol 4 (6) ◽  
pp. 4459-4506
Author(s):  
A. C. de Araújo ◽  
J. P. H. B. Ometto ◽  
A. J. Dolman ◽  
B. Kruijt ◽  
M. J. Waterloo ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Carbon Isotope ◽  
Isotope Ratio ◽  
Ecosystem Respiration ◽  
Nitrogen Concentration ◽  
Carbon Isotope Ratio ◽  
Dry Season ◽  
Atmospheric Co2 ◽  
Small Scale ◽  
Co2 Efflux

Abstract. The carbon isotope of a leaf (δ13Cleaf) is generally more negative in riparian zones than in areas with low soil moisture content or rainfall input. In Central Amazonia, the small-scale topography is composed of plateaus and valleys, with plateaus generally being drier than the valley edges in the dry season. The nocturnal accumulation of CO2 is higher in the valleys than on the plateaus in the dry season. The CO2 stored in the valleys takes longer to be released than that on the plateaus, and sometimes the atmospheric CO2 concentration (ca) does not drop to the same level as on the plateaus at any time during the day. Samples of sunlit leaves and atmospheric air were collected along a topographical gradient to test whether the δ13Cleaf of sunlit leaves and the carbon isotope ratio of ecosystem respired CO2 (δ13CR) may be more negative in the valley than those on the plateau. The δ13Cleaf was significantly more negative in the valley than on the plateau. Factors considered to be driving the observed variability in δ13Cleaf were: leaf nitrogen concentration, leaf mass per unit area (LMA), soil moisture availability, more negative carbon isotope ratio of atmospheric CO2 (δ13Ca) in the valleys during daytime hours, and leaf discrimination (Δleaf). The observed pattern of δ13Cleaf suggests that water-use efficiency (WUE) may be higher on the plateaus than in the valleys. The ;13CR was more negative in the valleys than on the plateaus on some nights, whereas in others it was not. It is likely that lateral drainage of CO2 enriched in 13C from upslope areas might have happened when the nights were less stable. Biotic factors such as soil CO2 efflux (Rsoil) and the responses of plants to environmental variables such as vapor pressure deficit (D) may also play a role.

scholarly journals Estimating Soil Moisture Distributions across Small Farm Fields with ALOS/PALSAR

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Yuki Kojima ◽  
Kazuo Oki ◽  
Kosuke Noborio ◽  
Masaru Mizoguchi
Keyword(s):  
Soil Moisture ◽  
Soil Layer ◽  
Ground Surface ◽  
Time Domain Reflectometry ◽  
Moisture Distribution ◽  
Small Scale ◽  
Alos Palsar ◽  
Coverage Ratio ◽  
Fine Resolution ◽  
Soil Moisture Distribution

The ALOS (advanced land observing satellite) has an active microwave sensor, PALSAR (phased array L-band synthetic aperture radar), which has a fine resolution of 6.5 m. Because of the fine resolution, PALSAR provides the possibility of estimating soil moisture distributions in small farmlands. Making such small-scale estimates has not been available with traditional satellite remote sensing techniques. In this study, the relationship between microwave backscattering coefficient (σ) measured with PALSAR and ground-based soil moisture was determined to investigate the performance of PALSAR for estimating soil moisture distribution in a small-scale farmland. On the ground at a cabbage field in Japan in 2008, the soil moisture distribution of multiple soil layers was measured using time domain reflectometry when the ALOS flew over the field. Soil moisture in the 0–20 cm soil layer showed the largest correlation coefficient with σ (r=0.403). The σ values also showed a strong correlation with the ground surface coverage ratio by cabbage plants. Our results suggested that PALSAR could estimate soil moisture distribution of the 0–20 cm soil layer across a bare field and a crop coverage ratio when crops were planted.

Exploring the use of machine-learning techniques to integrate ground- and remote sensing-based observations for efficient near-surface soil moisture mapping

2020 ◽  
Author(s):  
Sarah Schönbrodt-Stitt ◽  
Paolo Nasta ◽  
Nima Ahmadian ◽  
Markus Kurtenbach ◽  
Christopher Conrad ◽  
...  
Keyword(s):  
Machine Learning ◽  
Soil Moisture ◽  
Spatial Resolution ◽  
Surface Soil ◽  
Bare Soil ◽  
Small Scale ◽  
Surface Soil Moisture ◽  
Near Surface ◽  
Campania Region

&lt;p&gt;Mapping near-surface soil moisture (&lt;em&gt;&amp;#952;&lt;/em&gt;) is of tremendous relevance for a broad range of environment-related disciplines and meteorological, ecological, hydrological and agricultural applications. Globally available products offer the opportunity to address &lt;em&gt;&amp;#952;&lt;/em&gt; in large-scale modelling with coarse spatial resolution such as at the landscape level. However, &lt;em&gt;&amp;#952;&lt;/em&gt; estimation at higher spatial resolution is of vital importance for many small-scale applications. Therefore, we focus our study on a small-scale catchment (MFC2) belonging to the &amp;#8220;Alento&amp;#8221; hydrological observatory, located in southern Italy (Campania Region). The goal of this study is to develop new machine-learning approaches to estimate high grid-resolution (about 17 m cell size) &lt;em&gt;&amp;#952;&lt;/em&gt; maps from mainly backscatter measurements retrieved from C-band Synthetic Aperture Radar (SAR) based on Sentinel-1 (S1) images and from gridded terrain attributes. Thus, a workflow comprising a total of 48 SAR-based &lt;em&gt;&amp;#952;&lt;/em&gt; patterns estimated for 24 satellite overpass dates (revisit time of 6 days) each with ascendant and descendent orbits will be presented. To enable for the mapping, SAR-based &lt;em&gt;&amp;#952;&lt;/em&gt; data was calibrated with in-situ measurements carried out with a portable device during eight measurement campaigns at time of satellite overpasses (four overpass days in total with each ascendant and descendent satellite overpasses per day in November 2018). After the calibration procedure, data validation was executed from November 10, 2018 till March 28, 2019 by using two stationary sensors monitoring &lt;em&gt;&amp;#952;&lt;/em&gt; at high-temporal (1-min recording time). The specific sensor locations reflected two contrasting field conditions, one bare soil plot (frequently kept clear, without disturbance of vegetation cover) and one non-bare soil plot (real-world condition). Point-scale ground observations of &lt;em&gt;&amp;#952;&lt;/em&gt; were compared to pixel-scale (17 m &amp;#215; 17 m), SAR-based &lt;em&gt;&amp;#952;&lt;/em&gt; estimated for those pixels corresponding to the specific positions of the stationary sensors. Mapping performance was estimated through the root mean squared error (RMSE). For a short-term time series of &lt;em&gt;&amp;#952;&lt;/em&gt; (Nov 2018) integrating 136 in situ, sensor-based &lt;em&gt;&amp;#952;&lt;/em&gt; (&lt;em&gt;&amp;#952;&lt;/em&gt;&lt;sub&gt;insitu&lt;/sub&gt;) and 74 gravimetric-based &lt;em&gt;&amp;#952;&lt;/em&gt; (&lt;em&gt;&amp;#952;&lt;/em&gt;&lt;sub&gt;gravimetric&lt;/sub&gt;) measurements during a total of eight S1 overpasses, mapping performance already proved to be satisfactory with RMSE=0.039 m&amp;#179;m&lt;sup&gt;-&lt;/sup&gt;&amp;#179; and R&amp;#178;=0.92, respectively with RMSE=0.041 m&amp;#179;m&lt;sup&gt;-&lt;/sup&gt;&amp;#179; and R&amp;#178;=0.91. First results further reveal that estimated satellite-based &lt;em&gt;&amp;#952;&lt;/em&gt; patterns respond to the evolution of rainfall. With our workflow developed and results, we intend to contribute to improved environmental risk assessment by assimilating the results into hydrological models (e.g., HydroGeoSphere), and to support future studies on combined ground-based and SAR-based &lt;em&gt;&amp;#952;&lt;/em&gt; retrieval for forested land (future missions operating at larger wavelengths e.g. NISARL-band, Biomass P-band sensors).&lt;/p&gt;

scholarly journals The protective and attractive covering of a vegetated embankment using coir geotextiles

2006 ◽  
Vol 10 (4) ◽  
pp. 565-574 ◽  
Author(s):  
S. Vishnudas ◽  
H. H. G. Savenije ◽  
P. Van der Zaag ◽  
K. R. Anil ◽  
K. Balan
Keyword(s):  
Developing Countries ◽  
Soil Moisture ◽  
Watershed Management ◽  
South India ◽  
Soil Moisture Content ◽  
Small Scale ◽  
Attractive Alternative ◽  
Content Protection ◽  
Small Scale Industry ◽  
Steep Slopes

Abstract. This paper presents the results of a field experiment conducted in Kerala, South India, to test the effectiveness of coir geotextiles for embankment protection. The results reveal that treatment with geotextile in combination with grass is an effective eco-hydrological measure to protect steep slopes from erosion. In the context of sustainable watershed management, coir is a cheap and locally available material that can be used to strengthen traditional earthen bunds or protect the banks of village ponds from erosion. Particularly in developing countries, where coir is abundantly available and textiles can be produced by small-scale industry, this is an attractive alternative for conventional methods. This paper analyses the performance of coir geotextile in different treatments with respect to soil moisture content, protection against erosion and biomass production.

scholarly journals The Most Frequent Agronomic Practices Used by the Coconut Farmers in the “Coconut Triangle” of Sri Lanka

CORD ◽  
2018 ◽  
Vol 34 (2) ◽  
pp. 7
Author(s):  
Lalith Perera
Keyword(s):  
Soil Moisture ◽  
Sri Lanka ◽  
Information Sources ◽  
Cultural Practices ◽  
Training Programs ◽  
Low Cost ◽  
Small Scale ◽  
Agronomic Practices ◽  
Frequent Event ◽  
The Impact

The study was carried out to identify the most frequently practiced cultural practices by coconut growers in the main coconut growing area termed as “Coconut Triangle”, among a set of technical practices recommended by the Coconut Research Institute of Sri Lanka (CRISL). The objective was also to analyse the impact of these practices to the yield and to analyse the effects of the information sources to the growers to enhance the farmers skills. The study was carried out between June 2018 and August 2018. For the data collection, a questionnaire developed by CRISL was used and 62 growers were randomly selected. All the answers were gathered in a table file. Then, the data were analysed using tabular analysis and the software SPSS. The study reveals that most of the growers are having intercrops between the coconut trees, in large or very small scale even if the yield is lowand needs more space. For the soil moisture conservation around the coconut palm, the majority of the growers use the simple and low-cost technique; mulching around the coconut palms. However, 30.1% of the growers were found to not use any technique to improve the soil moisture even when the drought is a frequent event in the country, but this more valid for small scale growers. To improve their yield, majority of the growers preferred and used CRISL recommended coconut fertilizer mixture (Adult Palm Mixture or APM) over the other commercially available fertilizer mixtures. Finally, the study shows that farmers with large estates are the most involved to follow training programs and apply the advices given by the CRISL.           

scholarly journals Factors Controlling the Hydraulic Efficiency of Green Roofs in the Metropolitan Area of Milan (Italy)

2021 ◽  
Vol 13 (24) ◽  
pp. 13638
Author(s):  
Franco Salerno ◽  
Lucia Valsecchi ◽  
Riccardo Minoia ◽  
Diego Copetti ◽  
Gianni Tartari ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Significant Role ◽  
Flow Rate ◽  
Metropolitan Area ◽  
Green Roofs ◽  
Small Scale ◽  
Hydraulic Efficiency ◽  
Drainage Flow ◽  
Growing Media ◽  
Vegetative Period

Green roofs (GRs) are considered sustainable solutions for the adaptation of urban water management to climate change. The use of GRs is particularly promising in urban environments like the Metropolitan Area of Milan, the most urbanized area in Italy. In this work, we evaluated the subsurface runoff coefficient at the event-time scale, for more than one year of observations, of 68 small-scale test beds comprising different configurations of green roofs (e.g., different vegetations, types and depths of growing media, and different slopes) installed in the Metropolitan Area of Milan. The objectives of this study are three-fold. Firstly, the controlling factors of the hydraulic have been assessed for efficiency. We calculated a mean drainage flow rate of 51%, finding that growing media play a significant role in determining the drainage flow during the spring, at the beginning of the vegetative period. During this season, water retention in fertilized beds increases significantly. At the beginning of the summer, the vegetation cover is able to significantly reduce the drainage flow, playing an even more crucial role with respect to the growing medium material. However, we found that the vegetation type (grass field and Sedum) does not play a significant role in the retention processes. Secondly, the delay of the peak flow rate was determined. We found a precipitation peak delay from 1 to 2 h, which would be sufficient to guarantee environmental benefits for urban drainage. Finally, the factors controlling the hydraulic efficiency of GRs for individual precipitation events were assessed. We found that soil moisture and cumulated precipitation are both significant factors determining the drainage flow rate. In conclusion, we point out that soil moisture is one of the main parameters characterizing GR drainage and should be further considered in future research efforts devoted to the analysis of GR performance.

scholarly journals Topography-based modelling reveals high spatial variability and seasonal emission patches in forest floor methane flux

2020 ◽  
Author(s):  
Elisa Vainio ◽  
Olli Peltola ◽  
Ville Kasurinen ◽  
Antti-Jussi Kieloaho ◽  
Eeva-Stiina Tuittila ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Spatial Variability ◽  
Boreal Forest ◽  
Forest Floor ◽  
Methane Flux ◽  
Early Summer ◽  
Ground Vegetation ◽  
Small Scale ◽  
Ch4 Flux ◽  
Ch4 Uptake

Abstract. Boreal forest soils are globally an important sink for methane (CH4), while these soils are also capable to emit CH4 under favourable conditions. Soil wetness is a well-known driver of CH4 flux, and the wetness can be estimated with several terrain indices developed for the purpose. The aim of this study was to quantify the spatial variability of the forest floor CH4 flux with a topography-based upscaling method connecting the flux with its driving factors. We conducted spatially extensive forest floor CH4 flux and soil moisture measurements, complemented with ground vegetation classification, in a boreal pine forest. We then modelled the soil moisture with a Random Forest model using topography, based on which we upscaled the forest floor CH4 flux – this was performed for two seasons: May–July and August–October. Our results demonstrate high spatial heterogeneity in the forest floor CH4 flux, resulting from the soil moisture variability, as well as on the related ground vegetation. The spatial variability in the soil moisture and consequently in the CH4 flux was higher in the early summer compared to the autumn period, and overall the CH4 uptake rate was higher in autumn compared to early summer. In the early summer there were patches emitting high amounts of CH4, however, these wet patches got drier and smaller in size towards the autumn, which was enough for changing their dynamics to CH4 uptake. The results highlight the small-scale spatial variability of the boreal forest floor CH4 flux, and the importance of soil chamber placement in order to obtain spatially representative CH4 flux results. We recommend that a site of similar size and topographical variation would require 15–20 sample points in order to achieve accurate forest floor CH4 flux.

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