scholarly journals Effect of microrelief and water-table on vegetation dynamics in silty loam saline soils of coastal areas

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Mohammad Mansouri ◽  
Seyed Akbar Javadi ◽  
Mohammad Jafari ◽  
Hossein Arzani
Keyword(s):  
Water Table ◽  
Vegetation Structure ◽  
Soil Moisture Content ◽  
Floristic Composition ◽  
Growing Season ◽  
Soil Characteristics ◽  
Coastal Areas ◽  
Saline Soils ◽  
Silty Loam ◽  
Dynamics Of Vegetation

AbstractMicrorelief (MR) and water-table (WT) severely influence plant communities formation and development in silty loam saline soils of coastal areas. This research aimed to investigate the effect of MR and WT fluctuations on the dynamics of vegetation in coastal silty loam saline soils of southern Iran. Soil characteristics, vegetation structure and composition were investigated through the growing season, and obtained data were submitted to a canonical correspondence analysis. Based on the results, MR (min = 0.5 m and max = 1.0 m) and WT (max = 1 m) fluctuations significantly changed both structure and floristic composition through change in soil characteristics (Sig. < 0.05). Factors of soil moisture content, SAR and Na severely changed under MR and WT fluctuations and received new eigenvalues through the year. Our results demonstrated that a minimum change in MR and/or WT influence soil properties and vegetation structure and composition in silty loam saline soils of coastal areas.

scholarly journals WATER TABLE BEHAVIOR AND SOIL MOISTURE CONTENT DURING THE WINTER

1970 ◽  
Vol 50 (3) ◽  
pp. 361-366 ◽  
Author(s):  
J. C. van SCHAIK ◽  
E. RAPP
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Water Table ◽  
Soil Moisture Content ◽  
Growing Season ◽  
Grass Cover ◽  
Irrigation Project ◽  
Southern Alberta

Water table recession in an irrigation project in southern Alberta was compared with moisture translocation in covered lysimeters during two winters. Upward translocation to the surface 60 cm during one winter amounted to 1 to 2 cm of water in dry soils having a grass cover, and 2 to 2.3 cm in moist soils with no vegetation. Observations between growing season and freeze-up indicated that a considerable amount of water may drain downward. The upper 30 cm of soil generally is not influenced by upward translocation if the soil is dry before freeze-up.

scholarly journals MIGRATION OF SOLUBLE SALTS IN AN IRRIGATED FIELD IN RELATION TO RAINFALL AND IRRIGATION

1970 ◽  
Vol 50 (1) ◽  
pp. 43-45
Author(s):  
D. N. GRAVELAND
Keyword(s):  
Moisture Content ◽  
Water Table ◽  
Inverse Relationship ◽  
Soil Moisture Content ◽  
Salt Content ◽  
Growing Season ◽  
Soluble Salt ◽  
Soluble Salts ◽  
Sodic Soil ◽  
Precipitation Records

A saline sodic soil with a fluctuating water table was sampled once a week during the growing season and once every ten days until January to study the migration of soluble salts. The area, which was in pasture, was irrigated three times during the summer. The changes in soluble salt concentration were compared with the precipitation records, soil moisture content and water table levels. During the growing season, the soluble salt content varied over 100% and had an inverse relationship with moisture content.

scholarly journals Quantitative Estimation of Soil-Ground Water Storage Utilization during the Crop Growing Season in Arid Regions with Shallow Water Table Depth

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3351
Author(s):  
Tianxing Zhao ◽  
Yan Zhu ◽  
Jingwei Wu ◽  
Ming Ye ◽  
Wei Mao ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Ground Water ◽  
Shallow Water ◽  
Water Table ◽  
Soil Moisture Content ◽  
Water Storage ◽  
Growing Season ◽  
Water Table Depth ◽  
Arid Areas ◽  
Shallow Water Table

Water storage in unsaturated and saturated zones during the crop non-growing season is one of the important supplementary water resources to meet crop water requirements in arid areas with shallow water table depth. It is necessary to analyze utilization of the soil-ground water storage during the crop growing season and its attribution to irrigation during the non-growing season. To facilitate the analysis, a new method based on measurements of soil moisture content and water table depth is developed. The measurements used in this study include (1) 15-year data of soil moisture content within a depth of 1 m from the land surface and water table depth measured in Jiefangzha, including its four subareas and (2) 4-year data of the same kind in Yonglian, located in arid northern China. The soil-ground water storage utilization is calculated as the difference of water storage between the beginning and end of the crop growing season in the whole computational soil profile. The results of average soil-ground water storage utilization in Jiefangzha and its four subareas and Yonglian are 121 mm, 126 mm, 113 mm, 124 mm, 185 mm and 117 mm, and the corresponding average utilization efficiencies in the non-growing season are 32.2%, 32.5%, 31.5%, 31.6%, 57.3% and 47.6%, respectively. Further, the water table fluctuation method was used to estimate the variation in water storage. The coefficients of soil-ground water storage utilization, soil-ground water storage utilization below 1 m soil depth and ground water utilization are defined, and their average values are 0.271, 0.111 and 0.026 in Jiefangzha, respectively. Then, the contribution of soil-ground water storage utilization to actual evapotranspiration is evaluated, which are over 23.5% in Jiefangzha and Yonglian. These results indicate that the soil-ground water storage plays an important role in the ecological environment in arid areas with shallow water table depth.

Assessing the impact of exceptional inter-annual climatic variability on rates of net ecosystem carbon dioxide exchange at Clara bog.

2021 ◽  
Author(s):  
Matthew Saunders ◽  
Ruchita Ingle ◽  
Shane Regan
Keyword(s):  
Water Table ◽  
Elevated Temperatures ◽  
Ecosystem Respiration ◽  
Anthropogenic Activities ◽  
Climatic Variability ◽  
Growing Season ◽  
Carbon Dioxide Exchange ◽  
Mean Annual Temperature ◽  
Monitoring Networks ◽  
The Impact

&lt;p&gt;Peatland ecosystems are integral to the mitigation of climate change as they represent significant terrestrial carbon sinks. In Ireland, peatlands cover ~20% of the land area but hold up to 75% of the soil organic carbon stock however many of these ecosystems (~85% of the total area) have been degraded due to anthropogenic activities such as agriculture, forestry and extraction for horticulture or energy. Furthermore, the carbon stocks that remain in these systems are vulnerable to inter-annual variation in climate, such as changes in precipitation and temperature, which can alter the hydrological status of these systems leading to changes in key biogeochemical processes and carbon and greenhouse gas exchange.&amp;#160; During 2018 exceptional drought and heatwave conditions were reported across Northwestern Europe, where reductions in precipitation coupled with elevated temperatures were observed. Exceptional inter-annual climatic variability was also observed at Clara bog, a near natural raised bog in the Irish midlands when data from 2018 and 2019 were compared. Precipitation in 2018 was ~300 mm lower than 2019 while the average mean annual temperature was 0.5&amp;#176;C higher. The reduction in precipitation, particularly during the growing season in 2018, consistently lowered the water table where ~150 consecutive days where the water table was &gt;5cm below the surface of the bog were observed at the central ecotope location. The differing hydrological conditions between years resulted in the study area, as determined by the flux footprint of the eddy covariance tower, acting as a net source of carbon of 53.5 g C m&lt;sup&gt;-2&lt;/sup&gt; in 2018 and a net sink of 125.2 g C m&lt;sup&gt;-2&lt;/sup&gt; in 2019. The differences in the carbon dynamics between years were primarily driven by enhanced ecosystem respiration (R&lt;sub&gt;eco&lt;/sub&gt;) and lower rates of Gross Primary Productivity (GPP) in the drier year, where the maximum monthly ratio of GPP:R&lt;sub&gt;eco&lt;/sub&gt; during the growing season was 0.96 g C m&lt;sup&gt;-2&lt;/sup&gt; month in 2018 and 1.14 g C m&lt;sup&gt;-2&lt;/sup&gt; month in 2019. This study highlights both the vulnerability and resilience of these ecosystems to exceptional inter-annual climatic variability and emphasises the need for long-term monitoring networks to enhance our understanding of the impacts of these events when they occur.&lt;/p&gt;

scholarly journals An assessment of reclamation conditions in the irrigated lands of the Azerbaijan Republic

2010 ◽  
Vol 14 (1) ◽  
pp. 97-100
Author(s):  
Garib Mammadov ◽  
Agamir Hashimov
Keyword(s):  
Soil Texture ◽  
Soil Characteristics ◽  
Saline Soils ◽  
Irrigated Lands

An assessment of reclamation conditions in the irrigated lands of the Azerbaijan Republic Current reclamation condition of lands in the Azerbaijan Republic and differential assessment of saline soils depending on the soil characteristics (chemistry, soil texture etc.) are described in this paper.

scholarly journals From sink to source: long-term (2002-2019) trends and anomalies in net ecosystem exchange of CO2 from a Scottish temperate peatland.

2020 ◽  
Author(s):  
Karen Hei-Laan Yeung ◽  
Carole Helfter ◽  
Neil Mullinger ◽  
Mhairi Coyle ◽  
Eiko Nemitz
Keyword(s):  
Water Table ◽  
Ecosystem Respiration ◽  
Net Ecosystem Exchange ◽  
Growing Season ◽  
Water Table Depth ◽  
Sink Strength ◽  
Summer Drought ◽  
C Cycle ◽  
Dry Spell

&lt;p&gt;Peatlands North of 45&amp;#730; represent one of the largest terrestrial carbon (C) stores. They play an important role in the global C-cycle, and their ability to sequester carbon is controlled by multiple, often competing, factors including precipitation, temperature and phenology. Land-atmosphere exchange of carbon dioxide (CO&lt;sub&gt;2&lt;/sub&gt;) is dynamic, and exhibits marked seasonal and inter-annual variations which can effect the overall carbon sink strength in both the short- and long-term.&lt;/p&gt;&lt;p&gt;Due to increased incidences of climate anomalies in recent years, long-term datasets are essential to disambiguate natural variability in Net Ecosystem Exchange (NEE) from shorter-term fluctuations. This is particularly important at high latitudes (&gt;45&amp;#730;N) where the majority of global peatlands are found. With increasing pressure from stressors such as climate and land-use change, it has been predicted that with a ca. 3&lt;sup&gt;o&lt;/sup&gt;C global temperature rise by 2100, UK peatlands could become a net source of C.&lt;/p&gt;&lt;p&gt;NEE of CO&lt;sub&gt;2&lt;/sub&gt; has been measured using the eddy-covariance (EC) method at Auchencorth Moss (55&amp;#176;47&amp;#8217;32 N, 3&amp;#176;14&amp;#8217;35 W, 267 m a.s.l.), a temperate, lowland, ombrotrophic peatland in central Scotland, continuously since 2002. Alongside EC data, we present a range of meteorological parameters measured at site including soil temperature, total solar and photosynthetically active radiation (PAR), rainfall, and, since April 2007, half-hourly water table depth readings. The length of record and range of measurements make this dataset an important resource as one of the longest term records of CO&lt;sub&gt;2&lt;/sub&gt; fluxes from a temperate peatland.&lt;/p&gt;&lt;p&gt;Although seasonal cycles of gross primary productivity (GPP) were highly variable between years, the site was a consistent CO&lt;sub&gt;2&lt;/sub&gt; sink for the period 2002-2012. However, net annual losses of CO&lt;sub&gt;2&lt;/sub&gt; have been recorded on several occasions since 2013. Whilst NEE tends to be positively correlated with the length of growing season, anomalies in winter weather also explain some of the variability in CO&lt;sub&gt;2&lt;/sub&gt; sink strength the following summer.&lt;/p&gt;&lt;p&gt;Additionally, water table depth (WTD) plays a crucial role, affecting both GPP and ecosystem respiration (R&lt;sub&gt;eco&lt;/sub&gt;). Relatively dry summers in recent years have contributed to shifting the balance between R&lt;sub&gt;eco&lt;/sub&gt; and GPP: prolonged periods of low WTD were typically accompanied by an increase in R&lt;sub&gt;eco&lt;/sub&gt;, and a decrease in GPP, hence weakening the overall CO&lt;sub&gt;2&lt;/sub&gt; sink strength. Extreme events such as drought periods and cold winter temperatures can have significant and complex effects on NEE, particularly when such meteorological anomalies co-occur. For example, a positive annual NEE occurred in 2003 when Europe experienced heatwave and summer drought. More recently, an unusually long spell of snow lasting until the end of March delayed the onset of the 2018 growing season by up to 1.5 months compared to previous years. This was followed by a prolonged dry spell in summer 2018, which weakened GPP, increased R&lt;sub&gt;eco&lt;/sub&gt; and led to a net annual loss of 47.4 ton CO&lt;sub&gt;2&lt;/sub&gt;-C km&lt;sup&gt;-2&lt;/sup&gt;. It is clear that the role of Northern peatlands within the carbon cycle is being modified, driven by changes in climate at both local and global scales.&lt;/p&gt;

scholarly journals Vegetation structure and floristic composition of tree species in the habitat of Scaphium macropodum in Gunung Leuser National Park, Sumatra, Indonesia

2020 ◽  
Vol 21 (7) ◽  
Author(s):  
ARIDA SUSILOWATI ◽  
DENI ELFIATI ◽  
HENTI HENDALSTUTI RACHMAT ◽  
KUSUMADEWI SRI YULITA ◽  
ADI NURUL HADI ◽  
...  
Keyword(s):  
Tree Species ◽  
Vegetation Structure ◽  
National Park ◽  
Diversity Index ◽  
Good Condition ◽  
Floristic Composition ◽  
Line Transect ◽  
Growth Stages ◽  
Limited Information ◽  
Wiener Diversity Index

Abstract. Susilowati A, Elfiati D, Rachmat HH, Yulita KS, Hadi AN, Kusuma YS, Batu SAL. 2020. Vegetation structure and floristic composition of tree species in the habitat of Scaphium macropodum in Gunung Leuser National Park, Sumatra, Indonesia. Biodiversitas 21: 3025-3033. Scaphium macropodum (Miq.) Beumee Ex K Heyne is a member of Malvaceae tree species and globally recognized as malva nut and locally known as ‘kembang semangkok’, ‘tempayang’, ‘merpayang’ or ‘kepayang’. The nut of S. macropodum has many benefits for medicinal purposes, yet destructive extraction of this tree species has led them to extinction. Among its natural distribution in Indonesia, North Sumatra Province, Indonesia is known as its original range, but there is limited information about the existence of this species. This study aimed to determine the vegetation structure of some tree species in the habitat of S. macropodum in Sikundur, Gunung Leuser National Park, Sumatra, Indonesia. Purposive sampling technique was employed by creating line transect at some forest areas where the population of S. macropodum is known to grow naturally. Four line transects with each transect consisting of five plots with nested plots within were established to record data at four growth stages, resulting in 80 plots in total. The results showed that the Important Value Index (IVI) of S. macropodum within the floristic community at the studied area was 21.98, 13.85, 27.30, and 39.60 for tree, pole, sapling, and seedlings stages, respectively. The Shannon-Wiener Diversity Index (H) were 3.80, 3.70, 3.06 and 2.45, Index of evenness (E) are 0.94, 0.92, 0.86, 0.77 and the Index of Richness (R) are 11.76, 10.73, 6.59, 4.10 for tree, pole, sapling, and seedlings stages. This result suggests that the natural population of S. macropodum in Sikundur forest was still in good condition at all stages from tree to seedling.

scholarly journals Spatial and temporal variation of methane emissions in drained eutrophic peat agro-ecosystems: drainage ditches as emission hotspots

2008 ◽  
Vol 5 (2) ◽  
pp. 1237-1261 ◽  
Author(s):  
A. P. Schrier-Uijl ◽  
E. M. Veenendaal ◽  
P. A. Leffelaar ◽  
J. C. van Huissteden ◽  
F. Berendse
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Water Table ◽  
Soil Moisture Content ◽  
Explanatory Variable ◽  
Spatial And Temporal Variation ◽  
Spatial And Temporal Variability ◽  
Ch4 Emissions ◽  
Intensively Managed ◽  
Moisture Conditions

Abstract. Our research investigates the spatial and temporal variability of methane (CH4) emissions in two drained eutrophic peat areas (one intensively managed and the other less intensively managed) and the correlation between CH4 emissions and soil temperature, air temperature, soil moisture content and water table. We stratified the landscape into landscape elements that represent different conditions in terms of topography and therefore differ in moisture conditions. There was great spatial variability in the fluxes in both areas; the ditches and ditch edges (together 27% of the landscape) were methane hotspots whereas the dry fields had the smallest fluxes. In the intensively managed site the fluxes were significantly higher by comparison with the less intensively managed site. In all the landscape element elements the best explanatory variable for CH4 emission was temperature. Neither soil moisture content nor water table correlated significantly with CH4 emissions, except in April, where soil moisture was the best explanatory variable.

scholarly journals Partitioning CO<sub>2</sub> net ecosystem exchange fluxes on the microsite scale in the Lena River Delta, Siberia

2018 ◽  
Author(s):  
Tim Eckhardt ◽  
Christian Knoblauch ◽  
Lars Kutzbach ◽  
Gillian Simpson ◽  
Evgeny Abakumov ◽  
...  
Keyword(s):  
Water Table ◽  
Net Ecosystem Exchange ◽  
Growing Season ◽  
Arctic Tundra ◽  
High Water ◽  
Water Levels ◽  
River Delta ◽  
Lena River ◽  
Hydrological Conditions ◽  
Lena River Delta

Abstract. Arctic tundra ecosystems are currently facing rates of amplified climate change. This is critical as these ecosystems store significant amounts of carbon in their soils, which can be mineralized to CO2 and CH4 and released to the atmosphere. To understand how the CO2 net ecosystem exchange (NEE) fluxes will react to changing climatic conditions, it is necessary to understand the individual responses of the physiological processes contributing to CO2 NEE. Therefore, this study aimed: (i) to partition NEE fluxes at the soil-plant-atmosphere interface in an arctic tundra ecosystem; and (ii) to identify the main environmental drivers of these fluxes. Hereby, the NEE fluxes were partitioned into gross primary productivity (GPP) and ecosystem respiration (Reco) and further into autotrophic (RA) and heterotrophic respiration (RH). The study examined flux data collected during the growing season in 2015 using closed chamber measurements in a polygonal tundra landscape in the Lena River Delta, northeastern Siberia. The measured fluxes on the microscale (1 m–10 m) were used to model the NEE, GPP, Reco, RH, RA and net ecosystem production (NPP) over the growing season. Here, for the first time, the differing response of in situ measured RA and RH fluxes from permafrost-affected soils to hydrological conditions have been examined. It was shown that low RA fluxes are associated to a high water table, most likely due to the submersion of mosses, while an effect of water table fluctuations on RH fluxes was not observed. Furthermore, this work found the polygonal tundra in the Lena River Delta to be a sink for atmospheric CO2 during the growing season. Spatial heterogeneity was apparent with the net CO2 uptake at a wet, depressed polygon center being more than twice as high as that measured at a drier polygon rim. In addition to higher GPP fluxes, the differences in NEE between the two microsites were caused by lower Reco fluxes at the center compared to the rim. Here, the contrasting hydrological conditions caused the CO2 flux differences between the microsites, where high water levels lad to lower decomposition rates due to anoxic conditions.

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