Riparian vegetation life stages control the impact of flood sequencing on braided river morphodynamics

2021 ◽  
Author(s):  
Rocio L. Fernandez ◽  
Stuart McLelland ◽  
Daniel R. Parsons ◽  
Bas Bodewes
Keyword(s):  
Riparian Vegetation ◽  
Life Stages ◽  
Braided River ◽  
The Impact

scholarly journals Bulk Drag Predictions of Riparian Arundo donax Stands through UAV-Acquired Multispectral Images

Water ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1333
Author(s):  
Giuseppe Francesco Cesare Lama ◽  
Mariano Crimaldi ◽  
Vittorio Pasquino ◽  
Roberta Padulano ◽  
Giovanni Battista Chirico
Keyword(s):  
Riparian Vegetation ◽  
Vegetation Index ◽  
Arundo Donax ◽  
Water Bodies ◽  
Giant Reed ◽  
Multispectral Images ◽  
Drainage Channel ◽  
Area Index ◽  
Riparian Plants ◽  
The Impact

Estimating the main hydrodynamic features of real vegetated water bodies is crucial to assure a balance between their hydraulic conveyance and environmental quality. Riparian vegetation stands have a high impact on vegetated channels. The present work has the aim to integrate riparian vegetation’s reflectance indices and hydrodynamics of real vegetated water flows to assess the impact of riparian vegetation morphometry on bulk drag coefficients distribution along an abandoned vegetated drainage channel fully covered by 9–10 m high Arundo donax (commonly known as giant reed) stands, starting from flow average velocities measurements at 30 cross-sections identified along the channel. A map of riparian vegetation cover was obtained through digital processing of Unnamed Aerial Vehicle (UAV)-acquired multispectral images, which represent a fast way to observe riparian plants’ traits in hardly accessible areas such as vegetated water bodies in natural conditions. In this study, the portion of riparian plants effectively interacting with flow was expressed in terms of ground-based Leaf Area Index measurements (LAI), which easily related to UAV-based Normalized Difference Vegetation Index (NDVI). The comparative analysis between Arundo donax stands NDVI and LAI map enabled the analysis of the impact of UAV-acquired multispectral imagery on bulk drag predictions along the vegetated drainage channel.

Unele aspecte metodologice de studiu a biodiversitatii si productivitatii fitocenozelor din cadrul ecosistemelor urbane

2019 ◽  
Author(s):  
Constantin Bulimaga ◽  
◽  
Anastasia Portarescu ◽  
Keyword(s):  
Riparian Vegetation ◽  
Anthropogenic Activities ◽  
Natural Ecosystems ◽  
Impact Action ◽  
Productive Potential ◽  
Study Methodology ◽  
Biodiversity Study ◽  
The Impact ◽  
The City ◽  
Urban Activities

Anthropogenic activities cause damage to the natural ecosystems in the city in various ways, which contributes to the reduction of biodiversity. Considering that biodiversity is becoming more vulnerable to the impact action triggered by urban activities is necessary to monitor it in order to take urgent measures to protect and preserve it. The plant biodiversity study methodology includes methods that help determine phytocenosis parameters and assess biomass in order to estimate the productive potential of phytocenosis. Carrying out the research according to the proposed methodology will make it possible to assess the anthropogenic impact on the terrestrial and riparian vegetation.

scholarly journals MPA network design based on graph theory and emergent properties of larval dispersal

2020 ◽  
Vol 650 ◽  
pp. 309-326
Author(s):  
A Ospina-Alvarez ◽  
S de Juan ◽  
J Alós ◽  
G Basterretxea ◽  
A Alonso-Fernández ◽  
...  
Keyword(s):  
Graph Theory ◽  
Network Design ◽  
Early Life ◽  
Larval Dispersal ◽  
Network Connectivity ◽  
Life Stages ◽  
Early Life Stages ◽  
Larval Connectivity ◽  
The Impact ◽  
Mpa Network

Despite the recognised effectiveness of networks of marine protected areas (MPAs) as a biodiversity conservation instrument, MPA network design frequently disregards the importance of connectivity patterns. In the case of sedentary marine populations, connectivity stems not only from the stochastic nature of the physical environment that affects dispersal of early life stages, but also from the spawning stock attributes that affect reproductive output (e.g. passive eggs and larvae) and survivorship. Early life stages are virtually impossible to track in the ocean. Therefore, numerical ocean current simulations coupled with egg and larval Lagrangian transport models remain the most common approach for the assessment of marine larval connectivity. Inferred larval connectivity may differ depending on the type of connectivity considered; consequently, the prioritisation of sites for the conservation of marine populations might also differ. Here, we introduce a framework for evaluating and designing MPA networks based on the identification of connectivity hotspots using graph theoretic analysis. As a case study, we used a network of open-access areas and MPAs off Mallorca Island (Spain), and tested its effectiveness for the protection of the painted comber Serranus scriba. Outputs from network analysis were used to (1) identify critical areas for improving overall larval connectivity, (2) assess the impact of species’ biological parameters in network connectivity and (3) explore alternative MPA configurations to improve average network connectivity. Results demonstrate the potential of graph theory to identify non-trivial egg/larval dispersal patterns and emerging collective properties of the MPA network, which are relevant for increasing protection efficiency.

Riparian Vegetation Dynamic and River Stability on Intermittent Rivers: Impact of Water Transfer Project on Tropical Drylands

2021 ◽  
Author(s):  
Camilla Santos ◽  
Leonardo Dantas Martins ◽  
Kenia Sousa da Cruz ◽  
Jonas Otaviano Praça de Souza
Keyword(s):  
Vegetation Cover ◽  
Riparian Vegetation ◽  
Google Earth ◽  
Water Transfer ◽  
Lateral Stability ◽  
Hydrological Changes ◽  
Vertical Incision ◽  
Short Period ◽  
Geomorphic Units ◽  
The Impact

<p>Rivers on semiarid landscapes typically are characterised by sandy geomorphic units and riverbanks, a natural factor that enhances lateral mobility. Vegetation cover is a crucial factor on lateral instability due to its impact on riverbank and geomorphic units erosion resistance. Nevertheless, riparian vegetation on intermittent and ephemeral channels show growing patterns directly affect by the flow temporality, that controls the water availability. Extended dry intervals hinder the succession ecological on geomorphic units, like bars and islands, and riverbanks and retard the growing process. This work analysed the effects of hydrological changes, caused by one water transfer project, on the bio-geomorphological patterns on riverbanks of a main intermittent river of Brazilian Drylands. Flow data series was used to understand the hydrological pattern changes; Google Earth images and UAV surveys to analyse the vegetation and riverbank behaviour from 2008 to 2020.  Lastly, the identification of riverbank material resistance was based on sedimentology analysis.  The water transfer Project PISF (Projeto de Integração do São Francisco), operating since 2017 March, increase the average flow days from 137,5 to 260/300 days and decreasing the continuous dry period from 200 to 30/45 days. The impact on average annual discharge was slightest, whereas the average water transfer volume was 3m<sup>3</sup>/s. It is essential to highlight the short period of data posterior to the water transfer and the non-regulatiry of water volume transferred; what limits the temporal representativity of the results. There were different types, and level of impacts depending on the river reach characteristics. However, in general, the longer flow permanence increases riparian vegetation density, vertical incision, and lateral stability. Riparian vegetation cover increase, from 20% to 100% on the 9 reaches analysed, across the entire channel, including bedrock reaches, with riverbanks having some rock outcrops percentage. The main changes were on sand bed reaches, that used to have, before 2017, a dynamic braiding pattern, without a clear main incised channel and thalweg shifting. Afterwards, the flow permanence, due to the water transfer project, enabled herbaceous stratus temporal continuity, contributing to surface stability and progressive bushes/trees cover growing. Lastly, the increase in lateral stability, mainly on thalweg position, facilitates the vertical incision on the sand bed reaches, representing 85% of this channel. As a secondary impact, there were necessary, to the road network, built floodway crossings at several points, which changes the channel morphology and the (dis)connectivity process. It can generate distinct channel position and morphology changes causing water and sediment retention upstream and erosion downstream. Lastly, there were slight differences in textural characteristics on riverbanks and geomorphic units, with a rise in fine sediment on the most vegetated areas/units. This analysis reveals that a fast response of riparian vegetation and sand bed reaches morphology, affecting the bio-geomorphological process and all environmental dynamic. It points to fundamental elements which need monitoring after hydrological changes, especially to intermittent and ephemeral rivers.</p>

scholarly journals The Impact of Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) on Control of Dysmicoccus neobrevipes Beardsley (Hemiptera: Pseudococcidae)

Insects ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 131 ◽  
Author(s):  
Zhenqiang Qin ◽  
Jianhui Wu ◽  
Baoli Qiu ◽  
Shaukat Ali ◽  
Andrew G. S. Cuthbertson
Keyword(s):  
Prey Consumption ◽  
The Other ◽  
Life Stages ◽  
Functional Responses ◽  
Cryptolaemus Montrouzieri ◽  
Important Predator ◽  
Major Pest ◽  
Dysmicoccus Neobrevipes ◽  
The Impact ◽  
Agave Sisalana

Cryptolaemus montrouzieri (Coleoptera: Coccinellidae) is an important predator of the mealybug Dysmicoccus neobrevipes (Hemiptera: Pseudococcidae), a major pest of Agave sisalana in China. Limited reports on the efficacy of C. montrouzieri against D. neobrevipes are available. This study reports the predatory efficacy and functional response of C. montrouzieri against D. neobrevipes under laboratory conditions. The prey consumption rate per day of 4th instar larvae of C. montrouzieri feeding on 1st instar D. neobrevipes nymphs (241.3 mealybugs) was the highest among the different larval life stages of the beetle. For C. montrouzieri, the prey consumption per day of adult females (19.8 mealybugs) was significantly higher compared to males (15.2 mealybugs) when feeding on 3rd instar D. neobrevipes nymphs. The functional responses of C. montrouzieri on 1st and 2nd instar D. neobrevipes nymphs were determined as Holling type II. The search rates of C. montrouzieri 4th instar larvae towards the 1st and 2nd instar nymphs of D. neobrevipes were higher than those of the other beetle life stages. In addition, the handling times of 4th instar larvae were shorter than those of the other beetle life stages. The results from this study indicate that C. montrouzieri can be used as a predator of D. neobrevipes and, therefore, it should be evaluated further for use as a biocontrol agent in D. neobrevipes management programs.

scholarly journals Should we redefine meiofaunal organisms? The impact of mesh size on collection of meiofauna with special regard to nematodes

2020 ◽  
Vol 54 (4) ◽  
pp. 1135-1143
Author(s):  
C. Ptatscheck ◽  
S. Gehner ◽  
W. Traunspurger
Keyword(s):  
Mesh Size ◽  
Nematode Species ◽  
Life Stages ◽  
Collection Method ◽  
Benthic Food Web ◽  
Current Definition ◽  
Standard Collection ◽  
Benthic Food ◽  
Definition Of ◽  
The Impact

Abstract Meiofaunal organisms are the predominant metazoans in benthic systems and important members of the benthic food web. They are defined by mesh size and specifically by their retention on a sieve with a 44-µm mesh size. In this study, we examined the accuracy of this standard collection method by counting the number of meiobenthic individuals, life stages and nematode species in a sample. A filter cascade consisting of five different mesh sizes (41 µm, 30 µm, 20 µm, 10 µm and 1 µm) was used to fractionate a natural freshwater meiobenthic collection, and the individuals in each fraction were then counted. In line with the current definition of meiofauna, all tardigrades, microcrustaceans, chironomids and oligochaetes were retained by the largest mesh size, whereas 9% of the rotifers were first retained on the 30-µm meshes. For nematodes, 23% were not retained on the 41-µm meshes and individuals were collected even from the 1-µm fraction. With declining mesh size, the yield of retained nematodes increased, the age structure shifted to juveniles, evenness declined, and the species composition changed. As all of these findings were significant, this study therefore shows that the current definition of meiofauna is not sufficient to encompass the entire spectrum of meiofauna present in a sample and may result in misleading assessments of the diversity and composition of these organisms. We therefore propose that, especially for nematodes, a definition based on a smaller mesh size (at least 20 µm) is more appropriate.

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