Riparian vegetation Research Papers - Academia.edu (original) (raw)

The structural vegetation features of an isolated backdune patch of Ulmus minor wood was carried out. The small wood lies in a coastal protected area of Tyrrhenian central Italy and can be attributed to an initial stage of the association... more

The structural vegetation features of an isolated backdune patch of Ulmus minor wood was carried out. The small wood lies in a coastal protected area of Tyrrhenian central Italy and can be attributed to an initial stage of the association Aro italici-Ulmetum minoris. Such vegetation mainly occurs along rivers and floodplains on soil with low salinity. The averaged tree diameters significantly increase passing from the lower tree height classes to the higher ones. No significant difference along a dune-woodcore-backdune gradient, was observed. This fact suggests a weak/absent role of distance from the sea as factor affecting the tree growth. The gradient of abiotic factors is probably blocked by local pedological and geomorphological factors. The Ulmus minor wood patch studied does not follow the usual spatial pattern of the dune vegetation probably because: (i) Ulmus woods are unusual for dunal systems being linked to inland floodplains with low soil salinity; (ii) such vegetation corresponds to an early dynamic stage with a low species composition in its inner as well as in its outer area, which corresponds to the wood edge. As the Ulmus woods are rarely found on the Mediterranean coastal plains a further monitoring is necessary for a better explaining about the origin of such woodpatch and its dynamic relationship with the surrounding local vegetation.

This study examined the patterns of plant functional trait variation in relation to geomorphology, disturbance and a suite of other environmental factors in the riparian margin of the Upper Hunter River, New South Wales, Australia.... more

This study examined the patterns of plant functional trait variation in relation to geomorphology, disturbance and a suite of other environmental factors in the riparian margin of the Upper Hunter River, New South Wales, Australia. Vegetation was surveyed on three geomorphic surfaces (point bar, bench and bank) along a 5.5-km stretch of the Upper Hunter River. Functional traits relating to plant growth and reproduction were collected for the identified species. anova and principal components analysis were used to compare the trait assemblages of species associated with each geomorphic unit. Pearson's correlation coefficients were used to investigate trait variation with respect to environmental variables. There were clear differences in the plant functional trait assemblages associated with the three geomorphic units. Generally the point bar was associated with species that were herbaceous, with small seed mass, a short stature and a high specific leaf area (SLA). Conversely, the bench was associated with grasses that had unassisted seed dispersal and intermediate seed mass and SLA, while species on the bank had tall stature, large seed mass, a high SLA and a perennial life cycle. Variation along the primary gradient of plant functional trait composition was most strongly related to disturbance frequency and to a lesser extent soil nutrients and the proportion of clay and silt, while variation along the secondary gradient was associated with variation in substrate texture as well as soil nutrients.

Over the past 35 years, a trend of decreasing water clarity has been documented in Lake Tahoe, attributable in part to the delivery of fine grained sediment emanating from upland and channel erosion. A recent study showed that the Upper... more

Over the past 35 years, a trend of decreasing water clarity has been documented in Lake Tahoe, attributable in part to the delivery of fine grained sediment emanating from upland and channel erosion. A recent study showed that the Upper Truckee River is the single largest contributor of sediment to Lake Tahoe, with a large proportion of the sediment load emanating from streambanks. This study combines field data with numerical modeling to identify the critical conditions for bank stability along an unstable reach of the Upper Truckee River, California. Bank failures occur during winter and spring months, brought on by repeated basal melting of snow packs and rain-on-snow events. Field studies of young lodgepole pines and Lemmon's willow were used to quantify the mechanical, hydrologic, and net effects of riparian vegetation on streambank stability. Lemmon's willow provided an order of magnitude more root reinforcement (5.5 kPa) than the lodgepole pines (0.5 kPa); the hydrologic effects of the species varied spatially and temporally and generally were of a smaller magnitude than the mechanical effects. Overall, Lemmon's willow provided a significant increase in bank strength, reducing the frequency of bank failures and delivery of fine grained sediment to the study reach of the Upper Truckee River.

Abstract.,Anadromous,Pacific salmon (Oncorhynchus spp.) transport marine-derived nitrogen (MDN) to the rivers in which they reproduce. Isotopic analyses indicate that trees and shrubs near spawning,streams derive approximately 22 - 24% of... more

Abstract.,Anadromous,Pacific salmon (Oncorhynchus spp.) transport marine-derived nitrogen (MDN) to the rivers in which they reproduce. Isotopic analyses indicate that trees and shrubs near spawning,streams derive approximately 22 - 24% of their foliar nitrogen (N) from spawning salmon. As a consequence of this nutrient subsidy, growth rates are significantly increased in Sitka spruce (Picea sitchensis) near spawning,streams. As riparian forests affect

Riparian vegetation and management of surface water, the case of the Inaouène-Wadi watershed (NW Morocco). Integrated management of water resources interfere, directly or indirectly, with the biodiversity conservation. In Morocco, most... more

Riparian vegetation and management of surface water, the case of the Inaouène-Wadi watershed (NW Morocco). Integrated management of water resources interfere, directly or indirectly, with the biodiversity conservation. In Morocco, most studies on plant diversity of wetland interested especially ecological and functioning aspects. In this work, we tried to establish a relationship between human activities (planning, pollution …) and wetland flora and its conservation status. The specific plant diversity (Spermatophyta and Pteridophyta) of the Inaouène River was estimated based on the riparian flora exploration of 21 stations. The main ecological and anthropogenic factors (sampling, planning …) affecting plant groups were discussed as elements interfering with the rivers management. The study highlights the dependence of the population vis-à-vis plant resources, which may have a negative impact on surface water, and more rational measures should be taken, namely the plantation of the ...

Riparian vegetation performs important ecosystem functions, since it maintains regional biodiversity and provides a range of environmental services. However, anthropogenic activity, land use type, and edge effects are factors that modify... more

Riparian vegetation performs important
ecosystem functions, since it maintains regional
biodiversity and provides a range of environmental
services. However, anthropogenic activity, land use
type, and edge effects are factors that modify the
riparian species assemblage and properties. The
present study analyzes the influence of adjacent land
use on the structure and diversity of riparian vegetation
in four hydrographic regions that form the
watershed of the river Duero, in the state of Michoaca
´n, Mexico. Using a survey of woody plants of dbh
C 2.5 cm in ten different 0.1 ha sites, we found that
the average number of stems and individuals was
lower under agricultural (AGR) and urban (URB) land
use, compared to forested areas (FOR). The proportion
of multistemmed plants differs among land uses: this
value was greater in AGR than in the FOR and URB
categories. This proportion also differed among the
four hydrographic regions. The land use type FOR
presented the highest alpha and beta diversity, with a
high number of native species occurring only in areas defined by this land use. The results indicate that the
category FOR plays an important role in the conservation
of regional flora and is a possible source of
germplasm for restoration programs in sites degraded
by human disturbance. This study shows how anthropogenic
activities affect riparian vegetation and highlights
the importance of further study of this
ecosystem to apply sustainable management strategies
that are compatible with its conservation.

A modular procedure to assess the magnitude, distribution, and potential for channel instabilities at a large number of sites has been designed and implemented. The procedure, based on diagnostic interdisciplinary criteria of alluvial... more

A modular procedure to assess the magnitude, distribution, and potential for channel instabilities at a large number of sites has been designed and implemented. The procedure, based on diagnostic interdisciplinary criteria of alluvial channel morphology and associated riparian vegetation, is presented. The modules include (1) initial site evaluations, (2) GIS-based data input and management, (3) ranking of relative channel stability, (4) identification of spatial trends, (5) ranking of socio-economic impacts and identification of most “critical” sites, and (6) collection of additional field data for more detailed evaluation of the magnitude and type of future instabilities and the effects of proposed mitigation measures. The procedure, using site evaluation forms as the fundamental means of data collection, takes a trained person 1 to 1.5 hours to complete. Site evaluation forms can be altered according to the specific environment being studied and the objectives of the study.An objective ranking scheme based on physical attributes extracted from the GIS data base permits the identification of the most unstable channel sites and, thereby, focuses attention on potentially “critical” sites. If a significant concern about a bridge or adjacent lands arises, or if mitigation measures are considered, various methods to estimate future channel changes are proposed. These include (1) numerical alluvial channel modeling, (2) empirical models of channel evolution, (3) regime equations, and (4) empirical relations based on process dominance in different fluvial environments. The methods require differing amounts of additional field data and provide results of varying detail and accuracy. The decision on which method to use must be based on the objectives and resources of the agency involved in the evaluation study.

Hydrodynamics of vegetated channels and streams is a rapidly developing research area, and this chapter summarizes the current knowledge considering both aquatic and riparian zones. The benefit of an advanced parameterization of plant... more

Hydrodynamics of vegetated channels and streams is a rapidly developing research area, and this chapter summarizes the current knowledge considering both aquatic and riparian zones. The benefit of an advanced parameterization of plant morphology and biomechanical properties is highlighted. For this purpose, the response of flexible and foliated plants and plant communities to the flow is illustrated, and advanced models for the determination of drag forces of flexible plants are described. Hydrodynamic processes governing flow patterns in vegetated flows are presented for submerged and emergent conditions considering spatial scales ranging from the leaf to the vegetated reach scale.

Main channel and floodplain vegetation generally influence the flow behaviour in the flooding rivers or compound channels. The hydraulics of vegetated compound channels is complex and still not fully understood. The aim of the research... more

Main channel and floodplain vegetation generally influence the flow behaviour in the flooding rivers or compound channels. The hydraulics of vegetated compound channels is complex and still not fully understood. The aim of the research was to enhance the knowledge on the effects of two-line staggered arrays with closed-spacing emergent vegetation or roughness elements along the riparian zone on the non-mobile bed compound straight and meandering channels flows. The experiments were carried out in the hydraulics laboratory of Faculty of Civil Engineering, Universiti Teknologi Malaysia. The experimental investigations were focused on an asymmetrical compound straight channel and a straight, vertical floodplain-walls meandering channel with a sinuosity of 1.54. In addition, the Shiono and Knight Method (SKM) was examined to simulate the transverse distributions of velocity in non-vegetated and vegetated compound straight channels. The physical processes experimentally investigated were stage-discharge, flow resistance, three-dimensional turbulent flow structures, boundary shear stress, momentum transfer and drag force for selected flood flow depths in both compound channels. The densest riparian vegetation increased 6.1% and 32% of flow depth in compound straight and meandering channels, respectively. It also generated the largest flow resistance in both channels. The secondary currents movements were limited due to the presence of floodplain vegetation and the current strength in meandering channel was stronger than in straight channel. The floodplain vegetation also lowered boundary shear stress and a maximum of 77.8% boundary shear stress drop was observed for the densest vegetation case in compound meandering channel. Momentum transfers between main channel and floodplain were quantified as transverse Reynolds and apparent shear stresses. Peak stresses were found in the shear layer zones and increased with density of riparian vegetation. The vegetative-induced drag force FD was calculated using force balance approach and the result showed that it increased with flood flow depth. In addition, the smallest riparian vegetation spacing produced the largest drag coefficient CD in both non-mobile bed compound channels. The hydraulic simulations showed that SKM was able to produce well prediction of the depth-averaged velocity in non-vegetated and vegetated compound straight channels. The findings also revealed that compound meandering channel flow was more complex since its structures were spatially varied along the meander due to channel geometrical properties.

We present a regional land-use history of the Palouse bioregion of southeastern Washington and west-central Idaho. Our objectives were to develop a history of European-American settlement and biological diversity in the region and use... more

We present a regional land-use history of the Palouse bioregion of southeastern Washington and west-central Idaho. Our objectives were to develop a history of European-American settlement and biological diversity in the region and use this history to understand how human activities have altered the land cover and ecological integrity of the Palouse bioregion. We compiled and interpreted available information on

Strong feedbacks exist between channel dynamics, floodplain development and riparian vegetation. Earlier experimental studies showed how uniformly distributed riparian vegetation causes a shift from a braided to a single-thread river... more

Strong feedbacks exist between channel dynamics, floodplain development and riparian vegetation. Earlier experimental studies showed how uniformly distributed riparian vegetation causes a shift from a braided to a single-thread river because riparian vegetation stabilizes the banks and focuses discharge off the floodplains into channels. These experiments tested anemochorously distributed vegetation, i.e., by wind, whereas many riparian species in nature are also distributed hydrochorously, i.e., by flowing water. The objective of this study is to test experimentally what the different effects are of hydrochorously and anemochorously distributed vegetation on channel pattern and dynamics. The experiments were carried out in a flume of 3~m wide and 10~m long. We compared experiments with the two forms of vegetation distribution methods to control experiments without vegetation. To independently quantify bank retreat rate as a function of seed density and vegetation age, we used a small bank erosion test. In agreement with other work, the uniformly distributed vegetation decreased bank retreat, often stabilized banks and tightened meander bends. Vegetation seeds distributed by the flow during floods settled at lower elevations compared to the uniformly distributed vegetation. Inner bend vegetation stabilized a part of the point bar and hydraulic resistance of the vegetated bar forced water into the channel and over the floodplain. As a result, sediment was deposited upstream of vegetation patches. We conclude that seeds distributed by the flow during floods lead to island braiding: a patchy multi-thread river with stable vegetated bars, whereas vegetation uniformly distributed on the floodplain of a single-thread meandering river increases sinuosity and decreases bend wavelength. This implies that the combination of discharge variations and vegetation settling behavior has a large effect on the morphology and dynamics of rivers. The experimental approach opens up a wide range of possibilities to explore hydro-bio-geomorphological interactions with a high degree of control.

Rivers are conduits for materials and energy; this, the frequent and intense disturbances that these systems experience, and their narrow, linear nature, create problems for conservation of biodiversity and ecosystem functioning in the... more

Rivers are conduits for materials and energy; this, the frequent and intense disturbances that these systems experience, and their narrow, linear nature, create problems for conservation of biodiversity and ecosystem functioning in the face of increasing human influence. In most parts of the world, riparian zones are highly modified. Changes caused by alien plants — or environmental changes that facilitate shifts in dominance creating novel ecosystems — are often important agents of perturbation in these systems. Many restoration projects are underway. Objective frameworks based on an understanding of biogeographical processes at different spatial scales (reach, segment, catchment), the specific relationships between invasive plants and resilience and ecosystem functioning, and realistic endpoints are needed to guide sustainable restoration initiatives. This paper examines the biogeography and the determinants of composition and structure of riparian vegetation in temperate and subtropical regions and conceptualizes the components of resilience in these systems. We consider changes to structure and functioning caused by, or associated with, alien plant invasions, in particular those that lead to breached abiotic- or biotic thresholds. These pose challenges when formulating restoration programmes. Pervasive and escalating human-mediated changes to multiple factors and at a range of scales in riparian environments demand innovative and pragmatic approaches to restoration. The application of a new framework accommodating such complexity is demonstrated with reference to a hypothetical riparian ecosystem under three scenarios: (1) system unaffected by invasive plants; (2) system initially uninvaded, but with flood-generated incursion of alien plants and escalating invasion-driven alteration; and (3) system affected by both invasions and engineering interventions. The scheme has been used to derive a decision-making framework for restoring riparian zones in South Africa and could guide similar initiatives in other parts of the world.

The Białowieża Primeval Forest (BPF) is the only forest area in temperate Europe where forest communities have developed a natural stand structure and a natural distribution of coarse woody debris ((CWD)=standing dead trees (SDT)+down... more

The Białowieża Primeval Forest (BPF) is the only forest area in temperate Europe where forest communities have developed a natural stand structure and a natural distribution of coarse woody debris ((CWD)=standing dead trees (SDT)+down woody material (DWM)). Stand and dead wood characteristics are influenced by ancient and recent historical factors and current processes, such as fires, competitive exclusion, storms, insect outbreaks, and forest management. The aim of the present study was to relate CWD to stand characteristics in mesic deciduous forest (Tilio–Carpinetum (TC)) and riparian forest (Circaeo–Alnetum (CA)). Direct comparison of managed forest to protected forest provides information about the impact of the forestry practices on TC stand and CWD characteristics. Approximately two-fold larger volume of trees was found in the Białowieża National Park (BNP) TC stands (from 336 to 555 m3 ha−1) than in the commercial forest ((CF), from 239 to 279 m3 ha−1). Irregular distribution of “legacy trees” (DBH>90 cm) accounted for most of the variability among the TC BNP stands. Even stronger differences within TC stands were revealed among the various developmental phases (from 147 m3 ha−1 in degradation phase to 630 m3 ha−1 in biostatic-optimal phase). Difference in rate of stand development was responsible for the variability of tree volume within CA (338 m3 ha−1 in early succession stand versus 634 m3 ha−1 in close-to-climax stand). CWD (mostly DWM) contributed about one-quarter of the total above ground wood biomass in BNP TC and CA ecosystems, ranging from 87 to 160 m3 ha−1. Higher relative abundance of spruce in DWM than in living stand volume and more spruce in old debris than in fresh debris suggests that the end of the spruce mortality wave was imminent. As a consequence, structural and dynamic changes in favour of smaller regeneration units are expected. A mere vestige of CWD was found in the CF ecosystem. Both stand and CWD data show a negative impact of former management on the forest ecosystems. In conclusion, special measures aimed at the restoration of ecological capacity of forest communities, including legacy retention and management for decadence, have been recommended. There is an urgent need for complementary studies to supply information necessary for successful adaptive management of the Białowieża Primeval Forest.

Die Trinkwassergewinnung stellt nicht nur eine extensive Form der Landnutzung dar, sie ist auch mit Restriktionen hinsichtlich des landwirtschaftlichen Einsatzes von Dünge- und Pflanzenschutzmitteln innerhalb der Schutzgebietszone... more

Die Trinkwassergewinnung stellt nicht nur eine extensive Form der Landnutzung dar, sie ist auch mit Restriktionen hinsichtlich des landwirtschaftlichen Einsatzes von Dünge- und Pflanzenschutzmitteln innerhalb der Schutzgebietszone verbunden, welche zur Entstehung und zum Erhalt von für den Naturschutz wertvollem, artenreichem Magergrünland führen können. Nach Beendigung der Trinkwassergewinnung unterliegen diese Flächen oft der Gefahr einer weniger umwelt- und naturschutzverträglichen Landbewirtschaftung, so dass eine administrative Sicherung solcher wertvollen Flächen sinnvoll ist. Dabei gilt es zu ermitteln, welche Schutzgüter im betreffenden Gebiet
vorkommen und welche Qualitäten wertgebend für ein Schutzgebiet sind. Anhand des vorliegenden Beitrages soll dargestellt werden, welche naturschutzfachlichen Wertigkeiten die Flächen einer ehemaligen Trinkwassergewinnung in der Ruhraue in Bochum-Stiepel aufweisen und wie sie planerisch einzuordnen sind, damit sie durch adäquate Pflege- und Entwicklungsmaßnahmen langfristig erhalten werden können. Des Weiteren soll die floristische und vegetationskundliche Bedeutung des vorhandenen Grünlandes im regionalen Kontext für den Bochumer Raum und für das Ruhrgebiet dargestellt werden. Dabei werden aus pflanzengeographischer und naturschutzfachlicher Sicht bemerkenswerte Taxa der Gefäßpfl anzen gesondert kommentiert und der naturschutzfachliche Wert des Gebietes diskutiert.