Wet Depression Research Articles

Contributions of multispectral images to the study of land cover in wet depressions of eastern Tunisia

Eastern Tunisia is dotted with varied wetlands such as lagoons, sabkhas, garaas… These wetlands, at the interface between land and water, are rich, diverse and dynamic environments. Remote sensing shows potential and efficiency in the detection and characterization of these environments, although these humid depressions are difficult to define. The implementation of new optical satellite sensors characterized by High and Very High Spatial Resolution (HSR and VHSR) and by a high temporal repetitiveness, completes the field data and allows to envisage a delineation of the wet depression and a detailed detection of its land use. The purpose of this article is to determine whether the VHSR image, with its very rich spatial resolution, offers an added value for the detection of these diversified depressions, in comparison with the HSR image with richer spectral resolution. The results of the analysis show that the Ikonos image at VHSR compensates for the spectral richness of Sentinel-2 images at HSR. The “object-oriented” classification method, widely used today in image processing for various applications, appears to be more suitable than the “pixel-based” method in VHSR image classification. The Normalized Difference Water Index (NDWI) and the Transformed Soil Adjusted Vegetation Index (TSAVI) have multiple interests in wetland detection, although moisture masks show some inefficiency in improving the quality of classifications.

Atlantic St. John's Wort, Hypericum tenuifolium Synonym: Hypericum reductum

Atlantic St. John’s wort occurs throughout Florida and more broadly west to Alabama and northeast to North Carolina on beach dunes and scrub plant communities frequently associated with wet depression areas. Hypericum is a large genus of plants with 31 species in Florida alone (Wunderlin et al. 2017). This plant is a prolific flower producer that attracts numerous pollinators.https://edis.ifas.ufl.edu/sg170
 This publication is derived from information in SGEB-75/SG156, Dune Restoration and Enhancement for the Florida Panhandle, by Debbie Miller, Mack Thetford, Christina Verlinde, Gabriel Campbell, and Ashlynn Smith. https://edis.ifas.ufl.edu/sg156.

Response of plant diversity to moss, Carex or Scirpus revegetation strategies of wet depressions in restored fens

Pool margins and wet depressions (hollows) contribute considerably to peatland biodiversity by sheltering specific plant assemblages. In peatlands restored after peat extraction, the typical communities associated with pools generally fail to re-establish if only the moss layer transfer technique is applied, a common approach on flat bare peatlands. To adapt peatland ecological restoration methods for recolonizing shallow wet fen habitats, this study investigates the response of plant communities re-establishing in wet depressions subjected to four revegetation strategies. In a restored fen (southeastern Quebec, Canada), 48 depressions were dug out and revegetated with 1) mosses, 2) Carex species, 3) Scirpus validus, or 4) through spontaneous colonization (control treatment without implanted species). After four growing seasons, plant community structure and composition were surveyed in and outside the revegetated area respectively to test whether reintroduced communities had a propensity to extend beyond the central wet depression. Restoration strategies strongly impacted plant communities. Moss-revegetated wet depressions had higher moss and vascular fen-specialist species richness and distinct species assemblages relative to other treatments. Carex treatment increased only vascular cover compared to control, while Scirpus validus treatment did not differ from control. The positive impact of moss transfer was local and limited to core revegetated areas, as transferred plant material did not colonize any further. Our results suggest that transferring moss in created wet depressions is an effective strategy to foster the recolonization of diverse and distinct plant assemblages, and thereby restore local fen biodiversity hotspots.

Carbon accumulation in a permafrost polygon peatland: steady long-term rates in spite of shifts between dry and wet conditions.

Ice-wedge polygon peatlands contain a substantial part of the carbon stored in permafrost soils. However, little is known about their long-term carbon accumulation rates (CAR) in relation to shifts in vegetation and climate. We collected four peat profiles from one single polygon in NE Yakutia and cut them into contiguous 0.5 cm slices. Pollen density interpolation between AMS (14)C dated levels provided the time span contained in each of the sample slices, which--in combination with the volumetric carbon content--allowed for the reconstruction of CAR over decadal and centennial timescales. Vegetation representing dry palaeo-ridges and wet depressions was reconstructed with detailed micro- and macrofossil analysis. We found repeated shifts between wet and dry conditions during the past millennium. Dry ridges with associated permafrost growth originated during phases of (relatively) warm summer temperature and collapsed during relatively cold phases, illustrating the important role of vegetation and peat as intermediaries between ambient air temperature and the permafrost. The average long-term CAR across the four profiles was 10.6 ± 5.5 g C m(-2) yr(-1). Time-weighted mean CAR did not differ significantly between wet depression and dry ridge/hummock phases (10.6 ± 5.2 g C m(-2) yr(-1) and 10.3 ± 5.7 g C m(-2) yr(-1), respectively). Although we observed increased CAR in relation to warm shifts, we also found changes in the opposite direction and the highest CAR actually occurred during the Little Ice Age. In fact, CAR rather seems to be governed by strong internal feedback mechanisms and has roughly remained stable on centennial time scales. The absence of significant differences in CAR between dry ridge and wet depression phases suggests that recent warming and associated expansion of shrubs will not affect long-term rates of carbon burial in ice-wedge polygon peatlands.

Modeling the Heat Transfer during Log Heating

As one of the most commonly planted species in China, Masson pine (Pinus massoniana) logs are potentially used for structural poles and piles. Because phytosanitary regulations require that logs be heat-treated before delivery to customers (log core temperature of 56°C for 30 min), interest has recently arisen in the determination of the time required to reach this criterion. In this study, 12 logs were heat-treated in a laboratory drying kiln with two types of schedules. Using partial differential energy and mass conservation equations with gradient boundary conditions, the temperature increase in a log during heating was simulated. The boundary value problem of heat and mass transfer was solved using a numerical method, namely, a control volume approach. Results from the comparison between the observed and calculated temperatures indicated that the heat transfer performance during log heating can be described with this heating model. This model might therefore serve as a guideline for estimating the log heating times, assisting mill personnel in production planning. In addition, based on the experimental and calculated findings, it was well established that the log diameter, initial moisture content, wood density, and wet bulb temperature depression played significant roles in the heating rate during the heat treatment of logs.

Assessment of atmospheric moisture using hygroscopic salts in dry-and-wet climate of Nigeria

Atmospheric moisture content plays an important role in climate changes studies. Atmospheric moisture content was determined using four different hygroscopic salts, viz Sodium chloride (NaCl), Potassium chloride (KCl), Zinc sulphate (ZnSO4) and Magnesium chloride (MgCl2) salts and hygrometer. Evaluation of different hygroscopic salts for the determination of humidity was based on the ability of the salts to absorb atmospheric moisture. The affinity of salts for atmospheric water from measured value was compared with the hygrometer measured value. Data were subjected to one-way ANOVA using the Genstat statistical package (Release 4.24 Discovery Edition) to determine the weekly average of the moisture content and bulb depression. Duncan Multiple Range Test (DMRT), T-test and a linear regression model equation was generated with the fitness within 95%. The model of the regression was tested to determine the accuracy of equation compared with wet and dry bulb thermometer depression value. Magnesium chloride (MgCl2) offers the best result with significant coefficient (P = 0.01 and 0.05) and depression value of wet and dry bulb thermometer. The relative reliability of the use of hygroscopic salts in terms of accuracy of both measured and extrapolated humidity data utilization showed that these salts could be used in place of the usual hygrometer. Key words: Hygroscopic salts, hygrometer, atmospheric moisture, humidity.

Vegetation composition and soil microbial community structural changes along a wetland hydrological gradient

Abstract. Fluctuations in wetland hydrology create an interplay between aerobic and anaerobic conditions, controlling vegetation composition and microbial community structure and activity in wetland soils. In this study, we investigated the vegetation composition and microbial community structural and functional changes along a wetland hydrological gradient. Two different vegetation communities were distinguished along the hydrological gradient; Caricetum gracilis at the wet depression and Arrhenatheretum elatioris at the drier upper site. Microbial community structural changes were studied by a combined in situ 13CO2 pulse labeling and phospholipid fatty acid (PLFA) based stable isotope probing approach, which identifies the microbial groups actively involved in assimilation of newly photosynthesized, root-derived C in the rhizosphere soils. Gram negative bacterial communities were relatively more abundant in the surface soils of the drier upper site than in the surface soils of the wetter lower site, while the lower site and the deeper soil layers were relatively more inhabited by gram positive bacterial communities. Despite their large abundance, the metabolically active proportion of gram positive bacterial and actinomycetes communities was much smaller at both sites, compared to that of the gram negative bacterial and fungal communities. This suggests much slower assimilation of root-derived C by gram positive and actinomycetes communities than by gram negative bacteria and fungi at both sites. Ground water depth showed a significant effect on the relative abundance of several microbial communities. Relative abundance of gram negative bacteria significantly decreased with increasing ground water depth while the relative abundance of gram positive bacteria and actinomycetes at the surface layer increased with increasing ground water depth.

Variation in a Population of Plantago lanceolata along a Topographical Gradient

Patterns of variation were studied in a pasture population of Plantago lanceolata. Four subsites could be distinguished along a riverside gradient ranging from a dry ridge towards a wet depression (a former river-bed). A reciprocal-transplant experiment revealed differences between sites in mortality patterns, plant growth and reproduction. At some sites the native plants performed best; differences in survival in particular were observed during extreme abiotic circumstances, drought at the highest site and inundation at a low site (...)

Palynologie et climat

Palynology and climate Pollen analyst identifies in some types of sediments pollen grains and spores which have become fossilized. From the knowledge of the relations between pollen rains and present vegetation, one can deduce the existing relations between pollen contents of these sediments, ancient vegetation and past climate. Some examples, from the last 15 millenaries, allow to show the main trends of climate variation. Minor climatic fluctuations may be seen in some particular cases (evolution of altitudinal limit of forest, of vegetation in so me wet depression) and can be see n in relation with glacial front evolution.

Kankite from the Suzukura mine, Enzan city, Yamanashi Prefecture, Japan.

Kankite from the Suzukura mine, Yamanashi Prefecture, is found in a wet depression on the dump without accompanying any other secondary minerals than amorphous iron hydroxide. The wet chemical analysis containing 2.25% SO3 yields two alternative ideal formulae, FeAsO4·3H2O and Fe8 [(As,S)O4]7(H2O,OH)22–24, the former being close to the original one. Slight differences are found in DTA and TG curves and infrared absorption spectra from those of the original one, but the coincidence of X-ray powder diffraction pattern warrants the substantial identity.

Palynology of Pinedale Sediments, Devlins Park, Boulder County, Colorado

A core of varved lake sediments from Devlins Park, Front Range, Colorado, has yielded a radiocarbon-dated pollen record of environments during the last major advance of Pinedale ice. The downstream end of Devlins Park was dammed by Pinedale ice from 22,400 to 12,180 BP, creating the lake. The pollen diagram is dominated by Artemisia (40 to 60%) and Pinus (10 to 25%). Gramineae, Chenopodiaceae-Amaranthaceae, Compositae, Juniperus, and Picea pollen are also constantly present at low percentages. Arboreal pollen percentages are low, ranging from 13 to 30%. Pollen concentration varies from 6000 to 40,000 grains cc-~ of wet sediment. Modern pollen rain from a nearby wet depression is very different from the core pollen spectra, with greater percentages of Pinus (70%) and Picea (6%) pollen, less Artemisia (7%) pollen, and pollen concentration of 106,000 grains CC-'

Distribution and development of immature salt marsh Tabanidae (Diptera).

A 54,000-m2 study plot was systematically sampled to determine the distribution of Chrysops fuliginosus, C. atlanticus , and Tabanus nigrovittatus larvae in a regularly flooded Spartina alterniflora salt marsh. Soil samples were analyzed for salinity, percentage organic content, and pH. Distances of soil samples from the nearest drainage ditch were recorded. Of the 96 samples washed, 64.5% contained C. fuliginosus larvae, while only 14.6% and 17.7% yielded C. atlanticus and T. nigrovittatus , respectively. C. fuliginosus had a highly contagious distribution and coexisted with C. atlanticus and T. nigrovittatus in 11 samples. A significant negative correlation was computed for numbers of C. fuliginosus larvae collected and distances from drainage ditches. C. atlanticus larval occurrence was significantly correlated with salinity and percentage organic matter. C. atlanticus immatures were collected from very wet depression areas that bordered drainage ditches. T. nigrovittatus immatures were abundant throughout the open marsh in surface sediments that contained accumulations of very wet matted vegetation, but larval distribution was not correlated with salinity, percentage organic content, pH, or distance from drainage ditches. Small and large C. fuliginosus and T. nigrovittatus larvae were present in the marsh throughout all seasons; results suggest that some larvae of these speciesneed 2 years or more to mature.

Ecophysiological aspects of halophyte zonation in saline sloughs

The distribution of halophytes along the shoreline of a saline lake was studied in relation to the edaphic gradient, defined in terms of soil moisture, quality and quantity of dissolved solids, and osmotic and matric potential of the soil substrate. The edaphic gradient extends laterally from the wet depression area to the upslope drier area. The depression areas have low osmotic potential and support a luxurious growth ofSalicornia rubra but adversely affectDistichlis stricta, which grows best in the upslope area characterised by low matric potential of the substrate.

The distribution of wet bulb temperature depression

Climatological series of humidity data are defined. It is shown how such series are required for valid climatological analysis. Theoretical normal frequency distributions are proposed for dry bulb and wet bulb temperatures. From these, by theoretical considerations, the distribution of wet bulb depression is found to be a truncated normal distribution. Statistical estimates for the theoretical parameters are given and the fits of the theoretical wet bulb distributions verified on climatological series for three widely different climatic conditions. The effects of variation in the parameters of the wet and dry bulb distributions on the wet bulb depression distribution are discussed.

New or Otherwise Interesting Mosses from Alberta

Twenty-eight taxa of mosses are added to the 530 previously known taxa of bryophytes from Alberta. A recent compilation of the bryophyte taxa reported from Alberta (Bird, 1966), following the up-to-date nomenclature of Crum, Steere and Anderson (1965), enumerated 530 taxa. The present account adds 28 taxa and presents new data for five previously reported species. Voucher specimens have been deposited at UAc and CAN. Buxbaumia indusiata Brid. Waterton Lakes National Park: Trail from Cameron Creek to Lower Rowe Lake, Pinus contorta-Picea-Abies lasiocarpa forest, Crum & Schofield 6027. An uncommon boreal species which occurs on humus and well rotted logs. Calliergon richardsonii (Mitt.) Kindb. ex Warnst. Jumping Pound Creek Watershed: 10 mi. SE of Morley, wet depression in swampy Picea glauca forest, 4,500 ft., Hagel 43. Kananaskis River Watershed: Between Upper and Lower Kananaskis Lakes, partially submerged in pools in sedge fen, 5,700 ft., Bird & Glenn 13945. Banff National Park: Near Lake Louise, 5,000 ft., Crum & Schofield 3764. Jasper National Park: 4 mi. W of Giekie, swamp, 3,500 ft., Crum & Schofield 4769. An arctic-boreal species which occurs in pools and depressions in fens and wet forests. Cynodontium alpestre (Wahlenb.) Milde. Jasper National Park: Medicine Lake, humus on dry shaded cliff, 4,700 ft., Crum 3574. An uncommon boreal species of rock outcrops. Cynodontium tenellum (B.S.G.) Limpr. Elbow River Watershed: 6 mi. SW of the village of Bragg Creek, on dry exposed limestone rock, 4,750 ft., Seaborn 1314. Banff National Park: Windermere Highway, on cliff, 5,400 ft., Crum & Schofield 3728, 3739. A boreal species found on rocks in forested regions. In Alberta it occurs at mid-elevations (4,7505,400 ft.) in the mountains. Dichodontium pellucidum (Hedw.) Schimp. Bow River Valley: 3.5 mi. WSW of Exshaw, mixed woods, submerged on rock in spring-fed stream that does not freeze over in winter, 4,300 ft., Bird & Glenn 11123. Elbow River Watershed: Ford Creek, 2 mi. N of the Elbow River, on rocks submerged in rushing water, 5,740 ft., Bird 8770. Kananaskis River Watershed: Elpoca Creek, 3 mi. E of Lower Kananaskis Lake, wet rocks in rushing water, 6,500 ft., Bird & Glenn 13497. An arctic-boreal species of submerged rocks in

The Natural Conditions to the Founding of the old Capitals-Nagaoka, etc.

Among persons who have thought about the old capital at Nagaoka (784-794, the capital directly preceeding the one at Kyoto and to the south-west of modern Kyoto), there have been some who believed that the fact that in its center an ancient flood plain extended from north to south and that in its southeast quadrant there was a wet depression was an important reason for abandoning it. Having myself personally walked over the sites of the capitals which succeeded one another after the Taika Reform, 646 A.D., at Naniwa, Asuka, Otsu, Fujiwara, Heijo, Kuni, Heian, I have thought upon the natural conditions peculiar to the founding of the capitals.The first one was built along the upper reaches of the Asuka River where floods were few, and the later capitals gradually moved down toward broad plains and to wide slopes giving way to the southward. Still it is clear that the imperial palace which was the center of these capitals always stood upon an eminence or on the slope of one. And as their populations grew sites abundant in sail and water resources were looked upon with faver as capitals. As a result I perceived that Nagaoka with its hillock must have been a rather desirable site. I found, too, that the damp bottoms in its southeast were not in the old times flooded as much as people think. Therefore, I think it is not suitable to say that Nagaoka was abondoned because its site was disadvantageous.