The effects of disturbance on marsh seed banks

1985 ◽  
Vol 63 (12) ◽  
pp. 2133-2137 ◽  
Author(s):  
Loren M. Smith ◽  
John A. Kadlec
Keyword(s):  
Vegetation Change ◽  
Salt Lake ◽  
Open Water ◽  
Seed Banks ◽  
Water Levels ◽  
Distichlis Spicata ◽  
Vegetation Types ◽  
Physical Barriers ◽  
Normal Water ◽  
Standing Vegetation

Seed numbers and the species composition of seed banks (germinable seeds) from a marsh adjacent to the Great Salt Lake were compared among five vegetation types prior to a drawdown, during a drawdown, and prior to fire, after fire, and after restoration of normal water levels. Substrate samples were processed in the greenhouse under submersed and moist soil treatments to simulate the two germination conditions found in the field. After the fire, seed movement into the different vegetation types was also estimated. Numbers of germinable seeds were not depleted during the drawdown, possibly owing to increased salinity and the presence of standing vegetation. Fire had little effect on seed banks and subsequent seedling response. In general, seed banks were not affected by disturbance (e.g., burning, drawdown). The movement of seeds into the different vegetation types indicated that seed ingress could be important when one considers potential vegetation change. Seed banks of open water sites contained few germinable seeds when compared with Scirpus lacustris, S. maritimus, Distichlis spicata, and Typha spp. sites. Open water sites were devoid of vegetation and had few physical barriers, and seeds continued to move (air, water) across these areas until a barrier was reached, e.g., sites with vegetation.

Responses by benthic macroinvertebrates to prolonged flooding of marsh habitat

1986 ◽  
Vol 64 (1) ◽  
pp. 65-72 ◽  
Author(s):  
Henry R. Murkin ◽  
John A. Kadlec
Keyword(s):  
Organic Matter ◽  
Open Water ◽  
Benthic Invertebrate ◽  
Vegetation Types ◽  
Seasonal Differences ◽  
Marsh Habitat ◽  
South Central ◽  
Fine Particulate ◽  
Normal Water ◽  
Water Depths

This study examined the seasonal differences in benthic invertebrate densities and biomass within the dominant vegetation types in a series of 5-ha experimental marshes in south central Manitoba. Following periods of normal water depths, the marshes were flooded to 1 m above the existing cattail beds for up to 2 years to determine the benthic invertebrate response to prolonged above-normal flooding of the marsh habitat. Benthic invertebrate densities and biomass were low during periods of normal water depths when compared with levels later during flooding. The benthic response to flooding was primarily within the herbivore–detritivore group, especially nonpredaceous chironomids. All cover types other than former open-water sites showed increases in benthos densities, biomass, and numbers of taxa following flooding. The increases following flooding appear to be related to the death of the belowground components of the emergent vegetation, the availability of coarse organic litter early in flooding, and the development of fine particulate organic matter during flooding.

Soil seed banks and the effects of meadow management on vegetation change in a 10-year meadow field trial

2002 ◽  
Vol 39 (2) ◽  
pp. 279-293 ◽  
Author(s):  
R.S. Smith ◽  
R.S. Shiel ◽  
D. Millward ◽  
P. Corkhill ◽  
R.A. Sanderson
Keyword(s):  
Field Trial ◽  
Vegetation Change ◽  
Seed Banks ◽  
Soil Seed Banks

scholarly journals Model Predictive Control of a River Reach with Weirs

10.29007/1nnf ◽  
2018 ◽  
Author(s):  
Klaudia Horváth ◽  
Bart van Esch ◽  
Jorn Baayen ◽  
Ivo Pothof ◽  
Jan Talsma ◽  
...  
Keyword(s):  
Decision Support ◽  
Convex Optimization ◽  
Decision Support System ◽  
Model Predictive Control ◽  
Predictive Control ◽  
Support System ◽  
Water System ◽  
Open Water ◽  
Global Optimum ◽  
Water Levels

A decision support system for water management based on convex optimization, RTC-Tools 2, is applied for a water system containing river branches connected by weirs. The advantage of convex optimization is the ability of finding the global optimum, which makes the decision support system robust and deterministic. In this work the convex modeling of open water channels and weirs is presented. The decision support system is implemented for a river made of 12 river reaches divided by movable weirs. It is shown how the discharge wave is dispatched in the river without the water levels exceeding the bounds by controlling the weir heights. After this test the optimization can be applied to a realistic numerical model and model predictive control can be implemented.

scholarly journals Regulation of Vegetation and Evapotranspiration by Water Level Fluctuation in Shallow Lakes

Water ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 2651
Author(s):  
Qiang Liu ◽  
Liqiao Liang ◽  
Xiaomin Yuan ◽  
Sirui Yan ◽  
Miao Li ◽  
...  
Keyword(s):  
Water Level ◽  
Open Water ◽  
Water Area ◽  
Water Level Fluctuation ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Water Evaporation ◽  
Level Fluctuation ◽  
Open Water Area ◽  
Annual Scale

Water level fluctuations play a critical role in regulating vegetation distribution, composition, cover and richness, which ultimately affect evapotranspiration. In this study, we first explore water level fluctuations and associated impacts on vegetation, after which we assess evapotranspiration (ET) under different water levels. The normalized difference vegetation index (NDVI) was used to estimate the fractional vegetation cover (Fv), while topography- and vegetation-based surface-energy partitioning algorithms (TVET model) and potential evaporation (Ev) were used to calculate ET and water evaporation (Ep). Results show that: (1) water levels were dramatically affected by the combined effect of ecological water transfer and climate change and exhibited significant decreasing trends with a slope of −0.011 m a−2; and (2) as predicted, there was a correlation between water level fluctuation at an annual scale with Phragmites australis (P. australis) cover and open-water area. Water levels also had a controlling effect on Fv values, an increase in annual water levels first increasing and then decreasing Fv. However, a negative correlation was found between Fv values and water levels during initial plant growth stages. (iii) ET, which varied under different water levels at an annual scale, showed different partition into transpiration from P. australis and evaporation from open-water area and soil with alterations between vegetation and open water. All findings indicated that water level fluctuations controlled biological and ecological processes, and their structural and functional characteristics. This study consequently recommends that specifically-focused ecological water regulations (e.g., duration, timing, frequency) should be enacted to maintain the integrity of wetland ecosystems for wetland restoration.

scholarly journals Cladocera remains and vegetation types to assess the state of oxbows

2018 ◽  
Vol 29 ◽  
pp. 27-39
Author(s):  
István Gyulai ◽  
Csilla Lakatos ◽  
János Tamás Kundrát ◽  
Zsuzsanna Balogh ◽  
Edina Simon ◽  
...  
Keyword(s):  
Surface Sediment ◽  
Ecological Status ◽  
Open Water ◽  
Vegetation Types ◽  
Freshwater Lakes ◽  
Chemical Parameters ◽  
Habitat Types ◽  
Cladocera Remains ◽  
Significant Difference ◽  
Physical And Chemical

We assessed the usefulness of Cladocera remains for establishing the ecological status of oxbows and also tested the association of Cladocera species with various vegetation types. Cladocera remains were collected from the surface sediment of four habitat types (tangled vegetation, open water, reeds and tunnels) and 15 physical and chemical parameters of surface water were studied. In the surface sediment samples, we identified 32 Cladocera taxa. There was a significant difference in the number of species amongst habitat types as per ANOVA. The benthic and plant associated Cladocera communities of reeds, tangled vegetation, open water and tunnels were clearly separated from each other by NMDS ordination. CCA showed that habitat types had characteristic Cladocera species: Pleuroxus species were frequent in the tangled vegetation habitat, while Chydorus species were frequent in the open water. Remarkably, in reeds, Bosmina species were frequent, although these species are usually common in open water. Specimens of the Alona genus were found everywhere. Our findings suggest that the remains of Cladocera species may be useful indicators to assess and monitor the structure of freshwater lakes.

Emergent plant communities of oxbow lakes in northeastern Alberta: salinity, water-level fluctuation, and succession

1984 ◽  
Vol 62 (2) ◽  
pp. 310-316 ◽  
Author(s):  
V. J. Lieffers
Keyword(s):  
Water Level ◽  
Detrended Correspondence Analysis ◽  
Open Water ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Individual Species ◽  
Acorus Calamus ◽  
Oxbow Lakes ◽  
Salinity Water ◽  
Northeastern Alberta

Emergent vegetation was sampled in 15 oxbow lakes in a 50-km segment of the Athabasca River in northeastern Alberta. Cover of individual species was visually assessed in plots at the outer, middle, and (or) inner edge of the emergent zone of each lake (n, 37 sample units). Detrended correspondence analysis showed two main axes of variation. The first axis related to salinity. Water conductivity ranged from 170 to 12200 μS cm−1 and community types ranged from freshwater fens to saline wetland communities dominated by Scolochloa festucacea, Scirpus maritimus, and Triglochin maritima. The second axis of variation related to water-level fluctuations. Half of the lakes had an increase in water level in the recent past (ca. 6–30 years). In these lakes, Typha latifolia was dominant in both grounded and floating substrates subjected to increased water levels. Sedge communities dominated by Carex rostrata, C. aquatilis, and Acorus calamus were common in sites with stable water levels. In freshwater lakes, floating substrates were established over open water by the lateral growth of floating stems of Calla palustris and Potentilla palustris. Floating substrates were not in the saline sites probably because these open-water colonizers were not present under saline regimes.

Greening dynamics and shrubland extent from remote sensing data using NDVI and NARI Indices: case study of the George River basin (Nunavik, Canada).

2020 ◽  
Author(s):  
Dr. Jean-Pierre Dedieu ◽  
Johann Housset ◽  
Arthur Bayle ◽  
Esther Lévesque ◽  
José Gérin-Lajoie
Keyword(s):  
Remote Sensing ◽  
River Basin ◽  
Vegetation Change ◽  
Vegetation Index ◽  
Spectral Band ◽  
Human Populations ◽  
Vegetation Types ◽  
Local Study ◽  
Basin Scale ◽  
George River

<p>Arctic greening trends are well documented at various scales (Fraser et al., 2011; Tremblay et al., 2012; Bjorkman et al., 2018). In this context, Remote Sensing offers a unique tool for estimating the high latitude vegetation evolution in the relatively long-term, i.e. the Landsat archive since the 80’s. Spectral indices derived from visible and infra-red wavelengths provide relations that can be used to quantify vegetation dynamics, we will combine the well-used Normalized Difference Vegetation Index (NDVI) and the recent Normalized Anthocyanins Reflectance Index (Bayle et al., 2019), using red-edge spectral band (690 to 710 µm) from Sentinel-2, to better quantify vegetation change over 30 years.</p><p>The application area is located in Nunavik, northern Québec (Canada), and concerns the George River catchment (565 km length, 41 700 km²). This large river basin covers vegetation from boreal forest (South) to arctic tundra (North). Local study sites stem from the Kangiqsualujjuaq village (Ungava Bay) to 300 km south, along the main river and its tributaries.</p><p>NDVI: surface reflectance Landsat bands were gathered for three years 1985, 2000 and 2015 (respectively Landsat missions 5, 7 and 8). For each period of interest, the best August cloud-free scenes were chosen and merged to create a cloud free mosaic covering the study area. NDVI bands were calculated and compared after cloud and water masking. NDVI trends were compared between the main vegetation types following the newly released “Ecological mapping of the vegetation of northern Quebec” (MRNFP, 2018). Centroid of polygons within the main vegetation types of the map were used to classify the NDVI results and assess changes per type. Results of NDVI time evolution revealed a clear greening trend at the river basin scale. Although greening was observed across the whole latitudinal gradient, the relative NDVI increase was stronger on the northern half of the study area, mostly covered with tundra and subarctic vegetation. Both shrublands and sparsely vegetated zones dominated by rocks had the greatest relative NDVI increase. This is likely caused by improved growth of established prostrate vegetation over the past 30 years in response to increasing temperatures trend.</p><p>NARI: greening trends in the Eastern Canadian Arctic have been partly attributed to increases in shrub cover (Myers-smith et al., 2011) and specifically to Betula glandulosa (e.g. Tremblay et al., 2012). Such land cover changes alter species competition (Shevtosa et al., 1997) and soil thermal regime (Domine et al., 2015; Paradis et al., 2016). Transformations in biotic and abiotic conditions reduce the fruit productivity of low stature shrubs of the Ericaceae family (Lussier 2017), which in turn is expected to impact animal (Prescott and Richard 2013) and human populations (Lévesque et al., 2013; Boulanger-Lapointe et al., 2019). An innovative method has been developed in the French Alps to detect the late-fall reddening of shrub leaves and map shrublands (Bayle et al., 2019). Quantifying NARI dynamics related to NDVI dynamics could allow to gain a better understanding of species composition change related to current landscape transformation.</p>

Conditions of establishment for the Salix community at lower-than-normal water levels along a dam reservoir shoreline

2012 ◽  
Vol 9 (2) ◽  
pp. 227-238 ◽  
Author(s):  
Kazuhiro Azami ◽  
Asako Fukuyama ◽  
Takashi Asaeda ◽  
Yuko Takechi ◽  
Shigekazu Nakazawa ◽  
...  
Keyword(s):  
Water Levels ◽  
Dam Reservoir ◽  
Normal Water

Fire regime and vegetation change in the transition from Aboriginal to European land management in a Tasmanian eucalypt savanna

2016 ◽  
Vol 64 (5) ◽  
pp. 427 ◽  
Author(s):  
Louise M. Romanin ◽  
Feli Hopf ◽  
Simon G. Haberle ◽  
David M. J. S. Bowman
Keyword(s):  
Vegetation Change ◽  
Fire Regime ◽  
Plantago Lanceolata ◽  
Sediment Cores ◽  
Open Water ◽  
Fire Regimes ◽  
Ecological Impacts ◽  
14C Dating ◽  
Early 19Th Century ◽  
European Settlement

Using pollen and charcoal analysis we examined how vegetation and fire regimes have changed over the last 600 years in the Midlands of Tasmania. Sediment cores from seven lagoons were sampled, with a chronology developed at one site (Diprose Lagoon) using 210Pb and 14C dating. Statistical contrasts of six cores where Pinus served as a marker of European settlement in the early 19th Century and showed significant changes in pollen composition following settlement with (a) influx of ruderal exotic taxa including Plantago lanceolata L., Brassicaceae, Asteraceae (Liguliflorae) and Rumex, (b) increase in pollen of the aquatics Myriophyllum spp. and Cyperaceae, (c) a decline in native herbaceous pollen taxa, including Chenopodiaceae and Asteraceae (Tubuliflorae) and (d) a decline in Allocasuarina and an initial decline and then increase of Poaceae. The presence of Asteraceae (Liguliflorae) in the pre-European period suggests that an important root vegetable Microseris lanceolata (Walp.) Sch.Bip. may have been abundant. Charcoal deposition was low in the pre-European period and significantly increased immediately after European arrival. Collectively, these changes suggest substantial ecological impacts following European settlement including cessation of Aboriginal traditions of fire management, a shift in hydrological conditions from open water lagoons to more ephemeral herb covered lagoons, and increased diversity of alien herbaceous species following pasture establishment.

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