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Landscape-scale factors driving plant species composition in mountain streamside and spring riparian forests
... The greatest degree of plant species diversity is found in river valleys [1][2][3][4]. Further, diverse plant species play an essential role in shaping the physicochemical properties of flowing waters [5,6]. The species composition of plant communities occurring in the zone of river water flow depends mainly on water and soil conditions [4,[7][8][9]. ...
... Further, diverse plant species play an essential role in shaping the physicochemical properties of flowing waters [5,6]. The species composition of plant communities occurring in the zone of river water flow depends mainly on water and soil conditions [4,[7][8][9]. The direction and range of changes in the physicochemical parameters of waters are determined primarily by the species composition of plant communities, soil fertility, and anthropogenic factors [10][11][12][13]. ...
... For this purpose, water samples were collected in 500 mL polyethylene bottles. Bicarbonate (HCO 3 -) ion content was determined by titration with 0.1 mol × L -1 hydrochloric acid (HCl) solution, while K + , Na + , Ca 2+ , Mg 2+ , NH 4 + , Cl -, NO 3 -, PO 4 3and SO 4 2concentrations were assessed using ion chromatography (881 Compact IC pro, Metrohm, Switzerland). Further, Zn 2+ , Fe 3+ , Cu 2+ , Ni 2+ , and Mn 2+ concentrations were assessed using atomic absorption spectrometry (Analyst 300, Perkin-Elmer (USA)), and Al 3+ and Sr 2+ concentrations were determined by microwave plasma atomic emission spectrometry (Agilent 4100 MP-AES, Australia). ...
In this paper, we evaluated the effects of herbaceous plants and bryophytes on the physicochemical properties of waters flowing through the mid-forest spring niche. The research was carried out in the Kamienna River valley, in Northern Poland. In streams, submerged macrophytes belonging to the Pellio endiviifoliae-Cratoneuretum commutati community were found. Herbaceous plants (Cardamine amara, Glyceria plicata, Mentha aquatica, Stellaria uliginosa) and bryophytes (Brachythecium rivulare, Palustriella commutata, Pellia endiviifolia) of the highest classes of stability and with the highest cover coefficients were chosen for chemical research. During growing seasons, the pH and concentrations of potassium (K +), nitrate (NO 3-), sulfate (SO 4 2-), phosphate (PO 4 3-), iron (Fe 3+) and manganese (Mn 2+) ions in the stream flowing through the mid-forest spring niche were significantly modified by plants via the uptake and accumulation of macro-and trace elements C. amara had the greatest capacity to modify stream ion concentrations among the plants assessed. The plant stood out against other species with its above-average capacity to accumulate phosphorus (P), potassium (K) and magnesium (Mg). This species accumulated high quantities of nutrients (3,439.7 mmol × kg-1), which were mainly comprised of macroelements. On the other hand, in P. endiviifolia thalli, above-average levels of Fe and Mn were noted. The accumulation potentials of C. amara and P. endiviifolia indicate that the presence of these species significantly affect the physicochemical properties of water. This information has an important practical dimension, which is related to the potential use of C. amara and P. endiviifolia as water quality modifying agents.
... Local factors, including the physical and chemical characteristics of soils, water and groundwater fluctuations, have been frequently discussed in studies focused on vegetation-environment relationships (Härdtle et al. 2003;Hérault and Honnay 2005;Slezák et al. 2017). Local drivers may frequently interact with regional factors (e.g., landscape configuration, elevation and related climatic factors, specific hydro-morphological characteristics or solar radiation) to shape their species compositional variability (Douda 2010;Slezák et al. 2014;Pielech 2015;Pielech et al. 2015). In addition, historical processes such as postglacial migration of plants can influence species pool and community composition of alderdominated forests (Douda et al. 2018). ...
... Our results showed that a strong altitudinal effect also applies in azonal communities, which corroborated the results of previous research performed in floodplain forests at various spatial scales (Pielech 2015;Douda et al. 2016;Slezák et al. 2017). However, the dominance of the altitudinal gradient in riparian alder forests is not surprising because their altitudinal distribution is partly expressed by the turnover of dominant tree species in Central Europe; Alnus glutinosa prefers lower altitudes, while A. incana occupies mainly montane zones (Ellenberg 2009;Pielech et al. 2015). ...
... For example, the landscape history, the density of forest cover or the distance to the nearest settlement can modify the species composition (Douda 2010). GIS-derived topographic variables such as stream power index or wetness index were previously found to be linked with floristic variation of streamside forests (e.g., Pielech et al. 2015;Slezák et al. 2017). Besides, spatial differences in species composition of riparian alder forests could be partly driven by differences in species saturation among different regions given by historical, post-glacial migrations (Douda et al. 2018). ...
The effects of local and regional environmental variables as well as spatial gradients on the plant species composition of two types of alder-dominated forests (riparian forests and alder carrs) with contrasting connectivity were studied across the Western Carpathians from Hungary through Slovakia to Poland. We used large vegetation (240 sampling plots) and environmental (24 variables) datasets, which were accompanied by spatial variables represented by principal coordinates of neighbour matrices. Canonical correspondence analysis (CCA) of the two datasets revealed 13 and 29 variables with significant effects on variation in species composition of alder carrs and riparian alder forests, which jointly explained 41.2% and 36.4% of the variability, respectively. Altitude was the most important factor explaining 7.7% of the variability in the species composition of alder carrs and 8.2% in riparian alder forests. Variation partitioning in CCA revealed that local variables were crucial drivers for species composition patterns in alder carrs, while spatial processes unrelated to the measured environmental variables shaped the vegetation structure of riparian forests.
... Alder forests commonly create fragmented and small-scale forest stands due to the changes and transformation of the hydrological regime and fragmentation. These fragments are obviously influenced by adjacent landscape-scale factors [39]. Although these medium to species-rich forests [28,40] belong to threatened habitats at European or national levels (European Habitat Directive 92/43/EEC) [41,42], they represent a relatively frequent habitat in the Western Carpathians [23]. ...
... It is important to note that the soil variables (total nitrogen, plant-available phosphorus and C/N ratio) used as explanatory variables in our study explained together only between 8 and 16% of the variability in alien and native species richness in alder forests' understories, respectively. For a complex interpretation of variation in species richness or composition of vascular plants in streamside and alder carr forests, other habitat quality and landscape configuration-related factors have to be taken into account as well [20,21,39]. In more detail, habitat quality parameters, such as hydrological characteristics (e.g., water table, flooding), soil nutrient/acidity complex, temperature and light availability represent significant variables controlling vegetation structure of alder forests [20,22]. ...
... In more detail, habitat quality parameters, such as hydrological characteristics (e.g., water table, flooding), soil nutrient/acidity complex, temperature and light availability represent significant variables controlling vegetation structure of alder forests [20,22]. Moreover, the portion of surrounding country, distance to settlements or distance from the stream source plays the important role, as well [20,22,39]. These drivers could explain the major part of the variation in species richness-environmental relationships within temperate floodplain and swamp forests. ...
Soil nitrogen and phosphorus are commonly limiting elements affecting plant species richness in temperate zones. Our species richness-ecological study was performed in alder-dominated forests representing temperate floodplains (streamside alder forests of Alnion incanae alliance) and swamp forests (alder carrs of Alnion glutinosae alliance) in the Western Carpathians. Species richness (i.e., the number of vascular plants in a vegetation plot) was analyzed separately for native and alien vascular plants in 240 vegetation plots across the study area covering Slovakia, northern Hungary and southern Poland. The relationship between the species richness of each plant group and total soil nitrogen content, plant-available phosphorus and carbon to nitrogen (C/N) ratio was analyzed by generalized linear mixed models (GLMM) with Poisson error distribution and log-link function. The number of recorded native and alien species was 17–84 (average 45.4) and 0–9 (average 1.5) species per plot, respectively. The GLMMs were statistically significant (p ˂ 0.001) for both plant groups, but the total explained variation was higher for native (14%) than alien plants (9%). The richness of native species was negatively affected by the total soil nitrogen content and plant-available phosphorus, whereas the C/N ratio showed a positive impact. The alien richness was predicted only by the total soil nitrogen content showing a negative effect.
... For these reasons, we used spatial modelling of the stream power index (SPI) to quantify the disturbance magnitude during flood events (Pielech and Czortek, 2021) and the topographic wetness index (TWI) to estimate site moisture in riparian areas (Radula et al., 2018). The stream power index acts through the creation of exposed microsites either by sediment deposition or the removal of developed vegetation due to the erosive power of water (e.g., Pielech et al, 2015). Plant recruitment and successful establishment within new depositional bars subsequently depends on moisture availability or on depth of water saturation. ...
... Flooding typically leads to an increase in site productivity due to the release of abiotic resources, mainly solar radiation and the availability of nutrients (Pielech et al., 2015;Pielech and Czortek, 2021), which may generally either enhance the negative effect of competitive exclusions on species diversity (Reich et al., 2012) (Barbier et al., 2008;Gilliam and Roberts, 2014). More frequent flooding disturbances raise the observed light availability (Fig. 4d), typically by creating a mosaic forest structure with a fine-scale partitioning of light resources (Suzuki et al., 2002). ...
Disturbance regime and site productivity are considered the main factors shaping plant species assemblages and community diversity in riparian ecosystems, but whether and how topographic indices correlate with these two predictors remains largely unexplored. In this study, the stream power index (SPI) and topographic wetness index (TWI) were calculated as surrogates of flooding-induced disturbances and site productivity, respectively. We used a robust dataset of 879 vegetation plots sampled in temperate floodplain forests of Slovakia with the goal of testing the predictive power of interactions between the SPI and TWI on the diversity patterns of all vascular plants, ferns, woody species, aliens, neophytes and Red List species. Generalized additive models (GAMs) revealed the complementary importance of both predictors for explaining the species richness of different plant guilds in floodplain forests, including non-native and Red List species. The SPI and TWI accounted for 4.0–42.0% of the variation in species richness data, depending on species group, with the highest variation explained for ferns and the lowest variation explained for Red List species. Our results indicated that higher flooding-induced disturbances (SPI) associated with light availability increased the number of all species. Their richness declined towards less disturbed (SPI) sites with higher productivity (TWI) levels, where a higher rate of interspecific competitive exclusions is expected. In contrast, the species-reducing effect of frequent flooding (SPI) was recorded for aliens, neophytes and woody richness, with maximum richness values found at more productive sites. These trends differed from the patterns recognized for Red List species richness, which peaked at the intermediate disturbance (SPI) and productivity (TWI) levels. Our findings suggest that river networks with natural flow regimes and recurring episodes of floods facilitate species richness and simultaneously make riparian forests more resistant to plant invasions than regulated or channelized rivers. We confirmed that topographic indices represent tools for estimating the biodiversity status of floodplain forests, which could be useful in regions with a low rate of vegetation sampling or with insufficient cost and personnel capacities for vegetation monitoring. The TWI and SPI, as easily calculated measures, could be effectively applied to identify areas with various conservation and management targets.
... Riparian forests are of high natural and economic value, because they are rich in plant diversity [1,2] and significantly increase water retention in river valleys [3]. The species composition of flora of the woodland ecosystems is closely related to the chemical composition of soils [4] and water [5,6]. ...
... Water in streams presented small levels of electrolytic conductivity (180-544 µS cm -1 ), which show the lack of influence of anthropogenic pressure. Those values indicate low and moderate mineralisation of tested water, which underwent modification due to the contact with diverse plant cover growing along the banks of streams [2]. The concentration of dissolved oxygen was from 8.7 to 9.1 mg dm -3 on average, depending on the stream. ...
In this study, results of research related to the bioconcentration of N, P, K, Mg, and Ca in shoots of 20 species of herbaceous plants growing along three headwater streams in northern Poland are presented. Shoots of plants and water samples from streams were taken three times during growing seasons in the period between 2012 and 2014. Concentrations of nutrients in plants represented substantial diversity depending on species, sampling period, and the stream. Based on the results, it was found that many plant species take up nutrients in quantities exceeding their physiological demand, which makes them usable in water purification. Potassium (8,118–42,314), nitrogen (11,716–41,645), and phosphorus (11,607–37,459) had the highest levels of bioconcentration factors (BF). Lower values of BF referred to magnesium (1,161–2,973) and calcium (85–393). Results of Kruskall–Wallis test showed significant statistical differences in values of BF between examined plant species in reference to all analysed nutrients, depending on the stream. The highest value of N, P, K, Mg, and Ca BF were found in shoots of Filipendula ulmaria, Athyrium filix-femina, and Ranunculus acris; Veronica beccabunga, Chrysosplenium alternifolium, and Epilobium palustre; Veronica beccabunga, Ranunculus acris, and Chrysosplenium alternifolium; Filipendula ulmaria, Stellaria nemorum, and Epilobium palustre; and Chrysosplenium alternifolium, Geranium robertianum, and Cardamine amara, respectively.
... Riparian forests are of high natural and economic value as they significantly increase water retention in river valleys (Mazurek 2008). Riparian areas with diversified spatial and age structure of tree stands are distinguished by their superior richness of both forest-marsh flora and fauna (OsadOwski 2006, Pielech et al. 2015, Parzych et al. 2017. The species composition of flora of forest headwater ecosystems is closely related to the chemical composition of soils (JOnczak 2010 and groundwater flowing out onto the surface (Mazurek 2006. ...
... The lowest pH values were observed at all sites in May, which was a result of the early growing season and increased demand of plants for alkaline cations ). The waters were 1.9 ± 1.2 1.6 ± 1.5 -PO 4 3-(mg·dm -3 ) 0.4 ± 0.6 0.9 ± 0.8 p -level of statistical significance, EC -electrolytic conductivity characterized by relatively low mineralization, which was reflected by the electrolytic conductivity measured at an average level of 273 µS cm -3 in the stream water and 237 µS cm -3 in the groundwater (Pielech et al. 2015). The concentration of NH 4 + ions was on average 0.1 mg dm -3 in the stream waters and 0.9 mg dm -3 in the groundwater. ...
The paper presents results of a 3-year-long study (2012-2014) into the nitrogen and phosphorus bioaccumulation in 22 plant species associated with mid-forest headwater streams and in 10 plant species associated with peatbogs in the valley of the Kamienna Creek, a left bank tributary of the Słupia River, northern Poland. Plants were sampled in May, July and September of each year from three locations along the streams and three locations within the peatbogs. Every month stream water and ground water were sampled in the same locations using 30 cm piezometers. The content of nitrogen and phosphorus was determined in the plant and water samples. In the plant samples, total nitrogen was assessed with the Kjedahl method and phosphorus was determined with the molybdenum method. Concentrations of NH4+, NO2-, NO3- and PO43- in ground water samples were determined using ion chromatography. Stream and ground water contained low concentrations of mineral forms of these elements, which is associated with the strongly limited influence of anthropogenic factors and almost complete afforestation of the creek’s catchment. Despite this, the supply of plants with nitrogen and phosphorus was sufficient, which is confirmed by the concentrations of these elements in plants. However, peatbog plants accumulated the elements more intensively. The highest accumulation of nitrogen and phosphorus was found in the shoots of Urtica dioica. Among the stream plants, Brachythecium rivulare and Carex remota accumulated the least nitrogen. The average N:P ratio in plants, which was <10, suggests that nitrogen rather than phosphorus is a limiting factor for the plant growth in the analyzed ecosystem. Statistically significant Spearman correlation coefficients indicate that the concentrations of N and P in shoots of the tested plants were closely interdependent. Veronica beccabunga, Chrysosplenium alternifolium and Urtica dioica, accumulating the greatest amounts of N and P in their shoots, can be taken into account when constructing artificial wetlands intended to act as forest buffer zones.
... Flora and fauna of spring areas is characterized by a rich diversity [Decamps et al. 2004, Dosskey et al. 2010, Pielech et al. 2015. Specific physical and chemical properties affecting the surface of underground waters form the species arrangement of the flora found there. ...
... The differences in the quantity of accumulated elements are found not only among species, but they also depend on the vegetation season and the availability of components [Zhang et al. 2009]. The species composition of the forest headwater ecosystems is closely connected with the chemical composition of soils [ Jonczak et al. 2014, Jonczak at al. 2015a] and the flowing waters [Osadowski 2006] and is generally characterized by a high diversity [Pielech et al. 2015]. The interactions between plants, the water and the soil at these areas are very close and diverse [Karlssonet et al. 2005]. ...
The aim of the research was to compare the accumulative macro- and microelements in the shoots of Carex acutiformis, Carex echinata, Carex paniculata, Carex remota and Carex rostrata. The content of components in the shoots of the plants was analyzed as to the chemical composition of the soil. The research was done within the area of four mid-forest spring niches situated in the valley of a tributary of the Słupia River situated within the area of Leśny Dwór Forest Inspectorate (Northern Poland). The examined species of Carex, in comparison to other plants in spring niches, were characterized by an average capacity to accumulate both macro- and microelements, which decides about little interest in these species when planning artificial buffer zones. From among the analyzed species, the shoots of C. echinata accumulated the largest quantities of Mg, Zn and Mn, the shoots of C. paniculata of Fe, C. remota K, Ni, Al and Sr respectively, C. acutiformis of N and P, and the shoots of C. rostrata of Ca and Cu. Similarities between the species of Carex, which resulted from their accumulative properties, were discovered. C. echinata and C. rostrata were characterized by high levels of bioconcentration factors (BF) for Sr, Cu and Ca and the low BF for K. C. paniculata and C. remota represented high BF levels for Ni and Mg and low BF levels for Sr, Al, Mn, Cu, Ca, Fe and N. C. acutiformis was characterized by high BF levels for P, K and Mn. In spite of an average accumulative capacity, the examined species of Carex were characterized by highly developed above ground and underground zones which had effective impact on the retention of pollutants.
... In each catchment, we sampled five plots within each river order, ranging from one to six. In addition, we also sampled five plots of spring riparian forests, that is, forests growing in areas with groundwater discharge (also referred to as seepages or spring-fed areas [Pielech et al., 2015]). We decided to include spring forests in the longitudinal context of the study, as they are functionally and spatially linked to the hydrological system of the rivers, yet often neglected in riparian studies. ...
Questions
The River Continuum Concept (RCC) predicts a gradual shift of functional adaptations of organisms along the longitudinal (upstream–downstream) gradient, as well as the maximization of the biotic diversity in mid‐reaches. Although this theoretical framework was originally developed for stream macroinvertebrates, we tested whether such a pattern can also be observed in riparian plant communities.
Location
The study was conducted in the upper catchments of the San and Wisłoka Rivers in southeastern Poland. In both catchments, very well preserved riparian forests occur continuously along both rivers.
Methods
We studied the cover of plant species in riparian forests across two river networks. We analyzed the taxonomic and functional diversity indices, as well as community‐weighted means of functional traits in relation to the plots' positions in the catchments.
Results
The functional richness and divergence displayed unimodal patterns of increasing values in the mid‐reaches. The patterns of taxonomic diversity were similar, but some plots in the lowest reaches were more diverse than expected, forming an additional increase in diversity. The observed patterns were largely in line with the predictions of RCC. We discovered a significant decrease in the specific leaf area and an increase in the height of herbaceous plants in communities along a longitudinal gradient. There was also a shift in the dispersal syndromes, toward a higher importance of zoochory in the lower reaches.
Conclusions
The study shows that plant communities in natural riparian forests show continuous species turnover along the longitudinal gradient that, along with the longitudinal shift of abiotic factors, creates patterns that are known from theoretical predictions.
... The refugia based on the SR and the PD hotspots were observed in flatter areas along the rivers than those based on PD ses , which could be explained by habitat heterogeneity. The SR of riparian forests is higher than that in other upslope forests, probably due to the complex interactions of topographic factors, water flow, soil moisture, disturbance, and the corridor function of river valleys (Jansson et al., 2005;Kuglerova et al., 2014;Pielech et al., 2015;Pielech, 2021). ...
Identifying climatic refugia is important for long-term conservation planning under climate change. Riparian areas have the potential to provide climatic refugia for wildlife, but literature remains limited, especially for plants. This study was conducted with the purpose of identifying climatic refugia of plant biodiversity in the portion of the Mekong River Basin located in Xishuangbanna, China. We first predicted the current and future (2050s and 2070s) potential distribution of 50 threatened woody species in Xishuangbanna by using an ensemble of small models, then stacked the predictions for individual species to derive spatial biodiversity patterns within each 10 × 10 km grid cell. We then identified the top 17 % of the areas for spatial biodiversity patterns as biodiversity hotspots, with climatic refugia defined as areas that remained as biodiversity hotspots over time. Stepwise regression and linear correlation were applied to analyze the environmental correlations with spatial biodiversity patterns and the relationships between climatic refugia and river distribution, respectively. Our results showed potential upward and northward shifts in threatened woody species, with range contractions and expansions predicted. The spatial biodiversity patterns shift from southeast to northwest, and were influenced by temperature, precipitation, and elevation heterogeneity. Climatic refugia under climate change were related closely to river distribution in Xishuangbanna, with riparian areas identified that could provide climatic refugia. These refugial zones are recommended as priority conservation areas for mitigating the impacts of climate change on biodiversity. Our study confirmed that riparian areas could act as climatic refugia for plants and emphasizes the conservation prioritization of riparian areas within river basins for protecting biodiversity under climate change.
... Both the establishment and growth of this species are linked to riparian habitats that have been recently rejuvenated by floods, often characterized by large open areas, a moist substrate, high luminosity and little competition from other species . However, there is still a gap in the knowledge of how species dynamics respond to environmental factors under these conditions; and this knowledge is essential to better conserve, restore and manage threatened riparian pioneer habitats and their associated plant communities (Constança Aguiar et al., 2011;Pielech et al., 2015). ...
La dynamique de la végétation riveraine est étroitement liée aux régimes de perturbation du cours d’eau, notamment les crues, ainsi qu’aux processus physiques et biologiques qui en découlent. L’impact des activités humaines sur les rivières comme l’endiguement, la chenalisation ou l’exploitation hydroélectrique et sédimentaire, a fortement modifié ces régimes. Cela se traduit, entre autre, par une stabilisation du milieu et une régression des stades pionniers de l’habitat riverain due au manque de rajeunissement de celui-ci par les crues. A l’échelle de l’arc alpin, Typha minima Hoppe (la petite massette) est une espèce herbacée clonale qui colonise les habitats pionniers des cours d’eau de piémont. Cette espèce a vu ses populations fortement décroître au cours du siècle dernier, lui valant le statut d’espèce protégée dans plusieurs pays européens. En France, de nombreuses menaces pesant sur cette espèce persistent tel que la chenalisation, la modification du régime de crue et la destruction de son habitat par des travaux menés dans le lit et sur les berges des cours d’eau. C’est notamment le cas des travaux menés depuis 2004 par le Symbhi (Syndicat Mixte des Bassins Hydrauliques de l'Isère) dans le cadre du projet « Isère Amont » qui ont impacté des stations de T. minima sur l’Isère. Des mesures de compensations en ont résulté et ont accompagné la mise en place d’un projet de restauration de l’espèce dans la zone d’emprise des travaux.L’objectif de ce travail de thèse est de produire des connaissances sur la niche écologique et la dynamique spatiotemporelle d’une espèce clonale colonisant le stade pionnier de l’habitat riverain : la petite massette (Typha minima Hoppe), afin de servir de base théorique aux futurs projets de conservation et de restauration. Pour ce faire, la problématique suivante a été formulée : Quelles sont les variables environnementales et les processus écologiques qui affectent la dynamique spatio-temporelle de T. minima et en quoi ces connaissances peuvent-elles être appliquées à sa restauration et sa conservation?i) La première étape est de déterminer quels sont les facteurs biotiques et abiotiques liés aux processus sédimentaires et de succession écologique qui affectent la dynamique locale des taches de T. minima. Les résultats montrent que la progression des taches de T. minima est liée au caractère pionnier des bancs (sédiments fins, faible altitude et couvert végétal). Le maintien et la régression des taches sont au contraire liés à la maturité de l’habitat, induits par un processus de succession écologique plus avancé, avec un développement de la végétation et une amplification du phénomène d’accrétion.ii) Dans une seconde partie nous avons testé les effets de la compétition interspécifique avec des saules (Salix alba) et de l’ensevelissement par les sédiments sur la compétitivité et l’investissement dans la reproduction de T. minima. Bien que souvent mentionnée comme la principale cause de régression de l’espèce, la compétition interspécifique avec les saules n’affecte que peu T. minima alors que l’effet de l’ensevelissement par les sédiments est important.iii) Enfin, dans le but d’améliorer les protocoles de restauration de T. minima, plusieurs expérimentations visant à tester l’effet de différentes biomasses initiales transplantées, hauteurs par rapport à l’eau, types de berge, formes des placettes et associations avec d’autres espèces pionnières ont été réalisées entre 2013 et 2016. Les résultats montrent que transplanter T. minima avec une biomasse initiale importante sous forme de placette linéaire parallèle au cours d’eau à des hauteurs comprises entre +1.00m et +1.55m est optimal.Ces travaux caractérisent d’une part les facteurs environnementaux et les processus en jeu dans la dynamique de T. minima et d’autre part, optimisent les protocoles de restauration, contribuant ainsi à alimenter les futurs projets de restauration et de conservation de l’espèce.
... In studies focusing on vegetation-environment relationships, local factors have often been discussed, including physical and chemical properties of the soil and groundwater level fluctuations (Härdtle et al. 2003;Herault & Honnay 2005;Douda et al. 2009;van der Maaten et al. 2015;Slezák et al. 2017). The landscape configuration, altitude, and associated climatic factors, etc., are highly relevant (Douda 2010;Slezák et al. 2014;Pielech 2015;Pielech et al. 2015). In our study, it was shown that the effect of temperature on growth changes significantly from negative to positive with increasing altitude. ...
Black alder (Alnus glutinosa [L.] Gaertn.) is an important component of riparian and wetland ecosystems in Europe. However, data on the growth of this significant broadleaved tree species is very limited. Presently, black alder currently suffers from the pathogen Phytophthora and is particularly threatened by climate change. The objective of this study was to focus on the impact of climatic variables (precipitation, temperature, extreme climatic events) on the radial growth of alder across its geographic range during the period 1975-2015. The study of alder stands aged 46-108 years was conducted on 24 research plots in a wide altitude range (85-1015 m) in 12 countries of Europe and Asia. The most significant months affecting alder radial growth were February and March, where air temperatures are more significant than precipitation. Heavy frost and extreme weather fluctuations in the first quarter of the year were the main limiting factors for diameter increment. Within the geographical setting, latitude had a higher effect on radial growth compared to longitude. However, the most important variable concerning growth parameters was altitude. The temperature's effect on the increment was negative in the lowlands and yet turned to positive with increasing altitude. Moreover, growth sensitivity to precipitation significantly decreased with the increasing age of alder stands. In conclusion, the growth variability of alder and the number of negative pointer years increased with time, which was caused by the ongoing climate change and also a possible drop in the groundwater level. Riparian alder stands well supplied with water are better adapted to climatic extremes compared to plateau and marshy sites.
... Both the establishment and growth of this species are linked to riparian habitats that have been recently rejuvenated by floods, often characterized by large open areas, a moist substrate, high luminosity and little competition from other species . However, there is still a gap in the knowledge of how species dynamics respond to environmental factors under these conditions; and this knowledge is essential to better conserve, restore and manage threatened riparian pioneer habitats and their associated plant communities (Constança Aguiar et al., 2011;Pielech et al., 2015). ...
La dynamique de la végétation riveraine est étroitement liée aux régimes de perturbation du cours d’eau, notamment les crues, ainsi qu’aux processus physiques et biologiques qui en découlent. L ’impact des activités humaines sur les rivières comme l’endiguement, la chenalisation ou l’exploitation hydroélectrique et sédimentaire, a fortement modifié ces régimes. Cela se traduit, entre autre, par une stabilisation du milieu et une régression des stades pionniers de l’habitat riverain due au manque de rajeunissement de celui-ci par les crues .
A l’échelle de l’arc alpin, Typha minima Hoppe (la petite massette) est une espèce herbacée clonale qui colonise les habitats pionniers des cours d’eau de piémont. Cette espèce a vu ses populations fortement décroître au cours du siècle dernier, lui valant le statut d’espèce protégée dans plusieurs pays européens. En France, de nombreuses menaces pesant sur cette espèce persistent tel que la chenalisation, la modification du régime de crue et la destruction de son habitat par des travaux menés dans le lit et sur les berges des cours d’eau. C’est notamment le cas des travaux menés depuis 2004 par le Symbhi (Syndicat Mixte des Bassins Hydrauliques de l'Isère) dans le cadre du projet « Isère Amont » qui ont impacté des stations de T. minima sur l’Isère .Des mesures de compensations en ont résulté et ont accompagné la mise en place d’un projet de restauration de l’espèce dans la zone d’emprise des travaux.
L’objectif de ce travail de thèse est de produire des connaissances sur la niche écologique et la dynamique spatiotemporelle d’une espèce clonale colonisant le stade pionnier de l’habitat riverain : la petite massette (Typha minima Hoppe), afin de servir de base théorique aux futurs projets de conservation et de restauration. Pour ce faire, la problématique suivante a été formulée : Quelles sont les variables environnementales et les processus écologiques qui affectent la dynamique spatio temporelle de T. minima et en quoi ces connaissances peuvent elles être appliquées à sa restauration et sa conservation?
i) La première étape est de déterminer quels sont les facteurs biotiques et abiotiques liés
aux processus sédimentaires et de succession écologique qui affectent l a dynamique
locale des taches de T. minima . Les résultats montrent que la progression des taches de T. minima est liée au caractère pionnier des bancs (sédiments fins , faible altitude et couvert végétal). Le maintien et la régression des taches sont au contraire liés à la maturité de l’habitat, induit s par un processus de succession écologique plus avancé, avec un développement de la végétation et une amplification du phénomène d’accrétion.
ii) Dans une seconde partie nous avons testé les effets de la compétition interspécifique
avec des saules (Salix alba) et de l’ensevelissement par les sédiments sur la compétitivité
et l’investissement dans la reproduction de T. minima . Bien que souvent mentionnée
comme la principale cause de régression de l’espèce, la compétition interspécifique avec
les saules n’affecte que peu T. minima alors que l’effet de l’ensevelissement par les
sédiments est important.
iii) Enfin, dans le but d’améliorer les protocoles de restauration de T. minima, plusieurs plusieurs expérimentations visant à tester l’effet de différentes biomasses initiales transplantées, la hauteurs par rapport à l’eau, le types de berge, la forme des placettes et l'association avec d’autres espèces pionnières ont été réalisées entre 2013 et 2016. Les résultats montrent que transplanter T. minima avec une biomasse initiale importante sous forme de placette linéaire parallèle au cours d’eau à des hauteurs comprises entre +1.00m et +1.55m est optimal.
Ces travaux caractérisent caractérisent d’une part d’une part les facteurs environnementaux et les processus en jeu dans dans la dynamique de T. minima et d’autre part, optimisent les protocoles de restauration contribuant ainsi à alimenter les futurs projets de restauration et de conservation de l’espèce.
(Riparian vegetation dynamics are linked to river disturbance regimes including floods as well as physical and biological processes. Human activities such as containment, channelization, hydroelectric dam and sand gravel extraction have modified this regime. The main consequences are the stabilization of environmental parameters and the regression of pioneer stage driven by a lack of habitat rejuvenation by floods.
In the Alps, Typha minima Hoppe (the dwarf bulrush) is a clonal herbaceous plant species that colonizes pioneer stage habitat of piedmont rivers. It is a threatened species in the Alps because of the drastic decrease of its population during the last century. In France, the river channelization, the modification of flood regime and the works inside riverbed and banks still threaten relict populations. The Symbhi (Syndicat Mixte des Bassins Hydrauliques de l’Isère) initiated river works in 2004 through the “Isère Amont” project, impacted T. minima populations along the Isère and was mandated to set up a restoration project.
The main thesis objective is to produce knowledge about the ecological niche and spatiotemporal dynamics of a clonal plant species (T. minima) that colonizes pioneer riparian habitat. The following question is formulated: What are the environmental variables and ecological processes that affect the spatio-temporal dynamics of T. minima, and how could this knowledge be applied to its restoration and conservation?
i) The first step was to determine the biotic and abiotic parameters, linked to ecological succession and sediment accretion, involved in T. minima’s local patch dynamic. The results showed that local patch progression is linked to pioneer bar characteristics (fine sediment, low elevation and low vegetation cover). Patch maintenance and regression are related to more mature bar characteristics, induced by the progress of ecological succession and the accretion process amplification.
ii) Second, we experimented ex-situ the effects of interspecific competition and sediment burial on the competitive and reproduction abilities of T. minima. Although considered as the main cause of T. minima regression, we highlighted that interspecific competition with Salix alba has lower effect on T. minima than sediment burial.
iii) Last, to improve the restoration methods of T. minima we implemented in-situ experiments between 2013 and 2016. The objectives were to test the effects of initial transplanted biomass, transplantation elevation related to the mean water level, bank type, plot form and association with other pioneer species. The results show that transplantation with high or medium initial biomass in linear plots parallel to the water flow between +1.00m and +1.55m optimizes T. minima population restoration.
This work, that characterizes the environmental factors, the processes involved in T. minima’s local patch dynamics and that optimize the design of restoration protocols, contribute to improve future pioneer species restoration and conservation projects.)
... Both the establishment and growth of this species are linked to riparian habitats that have been recently rejuvenated by floods, often characterised by large open areas, a moist substrate, high luminosity and little competition from other species (Prunier et al., 2010). However, there is still a gap in the knowledge of how species dynamics respond to environmental factors under these conditions; and this knowledge is essential to better conserve, restore, and manage threatened riparian pioneer habitats and their associated plant communities (Constança Aguiar et al., 2011;Pielech et al., 2015). ...
• Changes in environmental variables induced by ecological succession and hydrogeomorphological processes affects riparian vegetation dynamics along rivers. The biotic and abiotic factors driving local patch dynamics of riparian species is little known for early successional stages.
• To fill this gap, we examined local patch dynamics and frequency of occurrence of a protected riparian pioneer species (Typha minima Hoppe) and related it to several biotic and abiotic variables along the Isère River (France) from 2016 to 2019.
• We monitored biotic and abiotic factors related to ecological succession and sediment accretion. We implemented Linear Mixed and Generalized Mixed Models to analyze how environmental factors affected patch boundary dynamics of T. minima. Finally, we built a Structural Equation Model to describe potential relationships between T. minima frequency, height above mean water level, vegetation cover and composition.
• We found that a thick layer of silt and sand deposits as well as a moderate herbaceous and low shrub cover layer characterized T. minima patch progression close to the mean water level. Typha minima stands did not seem to expand on coarser substrates with lower herbaceous cover. Its maintenance was associated with large silt and sand deposits and high cover of herbaceous plants and shrubs well above the mean water level. The variables characterizing patch regression were not clearly identified. Finally, the interaction between bar height, vegetation cover and succession stage did not explain variations in T. minima frequency.
• Our results provide knowledge about the environmental variables associated with T. minima patch dynamics, which are useful for future conservation and restoration projects. Habitat rejuvenation through restoration of natural river flow regimes could sustain local T. minima transplantation and large population turnover essential to the conservation of this species.
... Although local factors usually have a major impact on fine-grain species richness, several recent studies showed that riparian diversity is also influenced by landscape-scale factors. They include topography related variables like topographic wetness index, stream power index and potential solar radiation (Rodríguez- González et al., 2008;Douda, 2010;Pielech et al., 2015;Palmquist et al., 2018). Besides, several studies analyzed the linked effects of local and regional processes on riparian species richness (Hérault and Honnay, 2005;Kuglerová et al., 2015;Slezák et al., 2017;Leo et al., 2019). ...
This study aimed to analyze plant species richness in riparian forests at both local and regional scales across several watersheds in the Sudetes (Poland, Central Europe). Specifically, species richness in riparian forest was compared to other forest types in the same region. It was also hypothesized that due to high complexity and dynamics, riparian forests share a higher number of rare species. In addition, the longitudinal pattern of species richness was analyzed at both local and regional scales. Finally, the effect of topography on species richness in riparian forests in spring areas and along rivers of various sizes was analyzed.
Riparian forests have significantly higher alpha diversity than beech and ravine forests, but oak forests showed a similar level of diversity. However, a comparison of accumulation curves showed, that riparian forests are the most species-rich at a regional scale. All forest types had a similar share of rare species. Eight uniform groups of rare species were distinguished in riparian forests and reflected the riparian complexity and dynamics.
The number of plant species per plot was highest in spring areas and decreased from headwaters to lower reaches. The estimated total number of species showed a similar pattern; however, the highest number was estimated for riverine forests along 3rd order streams and therefore suggest a unimodal pattern of gamma diversity along a longitudinal (upstream–downstream) gradient. The effect of topographic variables on species richness differed depending on the position in the river network.
... For example, in riparian ecosystems, it is difficult to measure directly the amount of energy exerted by running water that influences the streamside vegetation during flood events. Instead, studies on the effects of disturbance intensity on riparian vegetation usually require either an experimental approach (Garssen et al., 2017;Konrad et al., 2011;Kotowski et al., 2010;Levine & Stromberg, 2001) or indirect methods, including spatial modeling of stream power (Bendix, 1999;Pielech et al., 2015), niche partitioning among hydrogeomorphic structures (Kyle & Leishman, 2009;Stoffel & Wilford, 2012), measurement of the amount of biomass removed by disturbance events (Eck et al., 2004;Garssen et al., 2015), or analysis of patterns of plant distribution along the longitudinal and lateral gradients (Araujo Calçada et al., 2015;Lite et al., 2005;Renöfält et al., 2005). ...
Ecological disturbances are recognized as a crucial factor influencing the attributes of ecological communities. Depending on the specific adaptation or life cycle, plant species show different responses to disturbances of different magnitudes. Herben et al. (Journal of Vegetation Science, 27, 628–636) proposed six disturbance indicator values (DIVs) that describe the niches of Central‐European plant species along gradients of disturbance frequency and severity. Here, we ask if the DIVs can be used in community ecology for bioindication of disturbance regime?
We used a dataset of riparian forests sampled within mountain catchments (the Sudetes, SW Poland). As the regime of disturbance is driven by changes in floods from the spring toward the mouth, we calculated the position of every plot along longitudinal (upstream–downstream) gradient and used it as a proxy for the disturbance severity and frequency. We then calculated the community‐weighted means (CWMs) for each of the six indices for each plot and analyzed whether these indices reflected the position of the plots along the rivers. We expected an increase in the severity indices and a decrease in the frequency indices downstream along the rivers. Moreover, we analyzed relationships between disturbance indices and species optima along longitudinal gradient.
Surprisingly, means for all analyzed indices increased along the rivers. Severity indices showed the strongest association with the longitudinal gradient. The disturbance severity index for herbs was the only index that differed significantly among species with different responses along longitudinal gradient. On these results, we identified a strong correlation between the severity and frequency indices as the main problem.
We conclude that the DIVs have considerable applicative potential; however, the determination of ecological niches separately for disturbance severity and frequency is difficult because different components interact to shape the realized niche of each species. All analyzed indices encompass different attributes of the disturbance regime including both severity and frequency.
... Riparian forests are considered to be one of the most diverse, dynamic and complex ecosystems in the world, while they are among the most sensitive, human-influenced and -threatened ecosystems as well [17]. The expansion of riparian woodland in flood-vulnerable areas could contribute both to flood control and other benefits, concerning the natural environment [18][19][20][21]. ...
The potential of woodland and floodplain woodland plantations in a wide area, of high flood risk, along the Spey River (Scotland) is investigated, to mitigate the floods' catastrophic impact. The spatial analysis required various datasets to be overlaid, to define the suitable sites for woodland and floodplain woodland establishment. These datasets that concern the topography, the physical and technical characteristics (existing woodland, road system, urban and rural areas, river system and open water areas, railway) and the protected sites of the study area were obtained and merged using Geographical Information System (GIS) techniques. The most suitable and unsuitable areas within the region were identified, using multi-criteria evaluation methods (Boolean approach). In total, 13 constraints were created by expressing true/false statements for each factor, and were combined together using spatial analysis tools. The results revealed the high potential of woodland and floodplain woodland plantations to prevent floods, with 59.2% of the total study area (177.5 Km 2) determined to be appropriate for such practices' application. The River Dulnain tributary demonstrated the highest potential for floodplain woodland planting, followed by Rivers Avon and Fiddich, and the southwestern and northeastern Spey River parts. The methodology proposed is simple and provides rapid and accurate results at low cost, while the datasets can be easily accessed and are available in convenient type/format. This useful methodology for researchers and authorities could be applied successfully to similar watersheds, contributing significantly to flood risk mitigation and the enhancement of the flood-preventative measures' planning efficiency.
... Inter-and intra-annual soil water dynamics create the mosaic of plant species assemblages with different moisture requirements. Soil moisture conditions can be closely coupled with some other environmental variables, for example light (Pielech et al. 2015), mineralisation rate of organic substrates (Qi et al. 2011) or soil solution chemistry and plant nutrient uptake (Misra and Tyler 1999), which in turn influence the floristic variation. Several floodplain forests with high level of biodiversity value and conservation importance occur in the study area. ...
Floodplain forests, as diverse plant communities commonly related to riparian zones, host plant species with various ecological niches and origins. The phytosociological context of floodplain forests has been well described on national level in many European countries, however, there are still regions with relatively poorly known variability of their species composition and environmental drivers controlling their vegetation patterns. Vegetation sampling of floodplain forests using traditional European phytosociological approach along with the recording of environmental (climatic, edaphic, topographic) variables was carried out in the northern part of the Western Carpathians (Slovakia and Poland) in period of 2011–2016. We gathered dataset of 135 original phytosociological relevés, which were classified using modified TWINSPAN algorithm. Five associations were distinguished: (i) meso-eutrophic black alder swamp forests (Carici acutiformis-Alnetum glutinosae), (ii) montane oligotrophic mixed spruce-alder forests on waterlogged sites (Piceo abietis-Alnetum glutinosae), (iii) riparian willow forests (Salicetum fragilis), (iv) meso-hygrophilous riparian alder forests (Stellario nemorum-Alnetum glutinosae) and (v) riparian grey alder forests (Alnetum incanae). Canonical Correspondence Analysis (CCA) with forward selection was used to show effect of environmental factors on species composition variation. The explained variance declined from marginal (13.9%) and conditional (8.6%) to pure effect (7.5%), with altitude (1.6%), total soil nitrogen content (1.6%) and soil pH (1.4%) being the most important predictors accounted for the highest variation in species compositional data.
... For instance, current velocity, width of the river, light availability, and accumulation to erosion ratio. The listed changes reflect in the changes of riparian vegetation [66]. There is also a link between distance from river's source and regime of disturbances driven by spates and floods. ...
We investigated the presence and abundance of invasive alien plant species (IAS) in the riparian zones of rivers in relation to different environmental parameters. We surveyed the spatial and human-influenced characteristics of the riparian zones, river channels, and land use along seven Slovenian rivers. We further monitored the presence and abundance of IAS with different natural properties and different human impacts to define the characteristics of non-infected and heavily infected reaches. Special attention was given to different life forms of IAS. The presence and abundance of IAS positively correlated with distance from river source, current velocity, and water depth, and negatively correlated with altitude, naturalness of the land use, width and completeness of the riparian zone, height and structure of its vegetation, and condition of the riverbed and banks. Annuals prevailed among IAS at 48%, with 37% herbaceous perennials and 15% woody species. The vine Echinocystis lobata was the most abundant IAS, which was found in 179 out of the 414 river reaches analysed, followed by the annual Impatiens glandulifera and the herbaceous perennial Solidago gigantea. E. lobata was spread over the native riparian vegetation and was affected by the natural gradients of the rivers in terms of altitude and distance from the river's source. Reaches without IAS significantly differed from reaches colonised with IAS in the width of riparian zone, vegetation height and structure, land-use next to the river, and distance from the source. As IAS in riparian zones affect riparian and aquatic communities, there is the need for management practices to maintain and establish complex riparian zones that are resistant to IAS colonisation.
... Earlier studies explaining complex vegetation-environment relationships in the riverine landscape often dealt with riparian forests [26][27][28][29][30][31][32] or secondary vegetation types, such as meadows [22,33,34]. However, the riparian tall herb fringe communities of the order Convolvuletalia sepium Tx. ex Moor 1958 represent an integral part of the natural vegetation in river valleys. ...
The riparian tall herb fringe communities of the order Convolvuletalia sepium represent an integral part of the natural vegetation in river valleys. The major objective of this study was to assess the relationships between the diversity and variability of these communities and various environmental factors. The survey was conducted in northwestern Poland, along 101 randomly selected 1–2-km long sections of 24 rivers and the Szczecin Lagoon. Samples were collected in 2008–2013 in all types of tall herb fringe vegetation found in the surveyed river sections. Data collected included hydrogeomorphic variables, soil parameters, potential and actual vegetation, and dominant land use form. A total of 24 vegetation units were documented, based on 300 sample plots (relevés). Tall herb fringe communities occurring in valleys of large rivers ( Senecionetum fluviatilis , Fallopio-Cucubaletum bacciferi , Achilleo salicifoliae-Cuscutetum lupuliformis , Convolvulo sepium-Cuscutetum europaeae typicum and chaerophylletosum bulbosi subass. nov., Rubus caesius community, Solidago gigantea community) exhibited floristic and ecological differences in comparison with plant communities from small rivers ( Eupatorietum cannabini typicum , aegopodietosum and cardaminetosum amarae subass. nov., Epilobio hirsuti-Convolvuletum sepium , Soncho palustris-Archangelicetum litoralis , Convolvulo sepium-Cuscutetum europaeae aegopodietosum , Urtico-Convolvuletum sepium typicum and aegopodietosum , Urtica dioica community, Galeopsis speciosa community, Rubus idaeus community). This finding fully justified their division into two alliances: the Senecionion fluviatilis and the Archangelicion litoralis , respectively. Significant differences between the tall herb fringe communities associated with large rivers and the plant communities occurring along small rivers included plant species richness, moss layer cover, contribution of river corridor plants, level of invasion, influence of adjacent plant communities on the floristic composition, relative elevation and distance away from the riverbed, degree of shading, proportions of all grain size fractions, soil pH, contents of organic matter, humus, organic carbon, total nitrogen, bioavailable phosphorus, potassium, magnesium, and calcium in the soil. The differences in environmental characteristics of individual plant communities were significant as well; they showed that most vegetation units were well defined. The variables that best discriminated between riparian tall herb fringe communities included the natural potential vegetation unit Salici-Populetum , headwater seeps, soil pH, sample elevation above the river water level, river size, flooding, degree of shading, soil moisture, K<sub>2</sub>O and CaO contents, and C/N ratio. The integration of the main riparian gradients (longitudinal, lateral, vertical) and patch perspective (e.g., natural potential vegetation units, and land use forms) significantly improved the comprehensive riparian vegetation patterns, because these two perspectives underpin different processes shaping the vegetation. This study contributed significantly to the knowledge of riparian tall herb fringe communities. Two subassociations are described here for the first time, whereas six others have not been previously reported from Poland. The data summarized in the synoptic table indicated that the species diagnostic for individual plant communities should be revised at the supra-regional scale. Some syntaxonomic issues were also determined. The inclusion of the order Convolvuletalia sepium to the class Epilobietea angustifolii resolved the problem of classifying the community dominated by Eupatorium cannabinum , a species showing two ecological optima: one in riparian tall herb communities and the other in natural gaps of the tree stands and clearings of fertile alder carrs and riparian woodlands. This also resolved the problem of classifying the communities dominated by Galeopsis speciosa and Rubus idaeus , intermediate between riparian tall herb and clearing communities. The results of this study may serve as a reference for management of the vegetation in river valleys and promote their conservation. They may also be essential for any future syntaxonomic revision of riparian tall herb fringe communities at a larger geographical extent.
... This is why the elevation-dependent gradient of zonation of the species may not be as clearly developed as it was reported by Bao et al. (2015). Generally, riparian vegetation characteristics in the temperate zone are related to topographical and hydrological parameters (flood effects) of the river and its valley (Pielech et al., 2015). Recent works suggest that the structure of riparian vegetation on a freeflowing river or a river downstream from a dam is more stable (e.g., González del Tánago et al., 2015) than in the WLF zone or drawdown zones of reservoirs (e.g., Chen et al., 2016). ...
Only in the years 2007–2016 about 8000 large dams were constructed all over the world, adding to >50,000 previously built dams. These structures disturb abiotic and biotic components of rivers, but to date the knowledge of their impacts has been mainly derived from observations of downstream river reaches. Upstream from dams, however, backwater fluctuations induce sediment deposition, cause more frequent and higher valley-floor inundation, increase groundwater level, and change channel morphology and riparian vegetation. Little is known on the effects of these disturbances on the river biogeomorphological processes.
In this review I synthesized knowledge on backwater effects on rivers into a model of backwater-induced abiotic–biotic interactions in the fluvial system. This model is next used to propose new hypotheses and research tasks concerning the biogeomorphology of gravel-bed rivers in the temperate climatic zone. Implications for flow–sediment–morphology–vegetation interactions and feedbacks are conceptualized in a river cross-section based on recent biogeomorphological insights and methodological approaches allowing to explore them in future studies. The model highlights that backwater-induced changes in abiotic and biotic components of river system trigger further feedbacks between them that additionally influence these components even without a direct backwater influence. Backwater-induced changes in hydrodynamics and sediment transport favour seed germination and growth of plants and decrease their mortality during floods, but also eliminate plants intolerant to prolonged inundation and intensive fine sediment deposition. These impacts may change the biogeomorphical structure of river system by modifying trajectories of biogeomorphic succession cycles and related zones of vegetation–hydromorphology interactions in the river corridor. Specifically, backwater effects may promote the development of more stable channel morphology and a less diverse mosaic of riparian vegetation and animals habitats, contrasting with those occurring in free-flowing rivers of the temperate zone.
... Numerous studies have investigated vegetation-environment relationships. Most have analyzed the impact of chosen factors on vegetation [4][5][6][7][8][9][10][11][12][13]. Among them, stream power, flood duration, various topographic variables, soil pH, content of nutrient elements or heavy metals in the soil, light intensity, soil texture, groundwater discharge, and level of the water-table are notable. ...
Two species of the genus Petasites , P. kablikianus (occurs upstream) and P. hybridus (occurs downstream), form characteristic tall herb communities in two altitudinal zones of Carpathian streams and rivers. They are described as “altitudinal vicariants” due to their substitution with decreasing elevation on similar habitats along mountain streams. This would indicate that the phenomenon is conditioned by climatic factors. In this study, we investigated the factors that determine this substitution on streambanks, and whether P. hybridus competes with P. kablikianus and limits its spread from mountains to foothills. We analyzed 72 plant patches from the Western and Eastern Carpathians in terms of flora composition, and geomorphological features of the habitat. The content of organic matter, available Mg, P, K, C, total N, and pH were also analyzed for a representative group of patches. Phytocoenoses were analyzed based on the presence of one of the analyzed species or on the quantitative proportions, in the case of a co-occurrence. We found statistically significant differences in the soil structure (skeleton percentage), content of Mg, N, and C, and the values of the C:N ratio. These results revealed that P. kablikianus prefers skeletal soils with a lower clay content, that is rich in Mg, N, C, and organic matter. Petasites hybridus prefers finer soils, which are richer in pulverized and clay fractions, in a zone of decrease of soil richness and where a thick layer of humus is typical for its phytocoenoses. We found that the spread of P. kablikianus into lower locations is not limited by competition with P. hybridus , but rather by the quality and structure of the habitat. Therefore, both species should be treated as ecological rather than altitudinal vicariants.
... Riverine areas are among the most altered ecosystems by river regulation, settlement, agricultural land use and invasion of alien species (e.g. Dyderski et al., 2015;González et al., 2017;Lapin et al., 2016;Nilsson et al., 2005;Pielech et al., 2015). Broadleaved forests in river valleys have been transformed into agricultural fields or monocultures of coniferous tree species, making them among the most modified and fragmented ecosystems in Europe (Petersen et al., 1987;Sedell and Froggatt, 1984). ...
Riparian forests are among the most threatened ecosystem types worldwide. Their exploitation and replacement by coniferous plantations affects species pools and contributes to loss of biodiversity. We aimed to investigate bryophyte species pools within different habitat types in a transformed mountain river valley. We especially focused on the contribution of habitat types (relative to their proportional cover) to the species pool of the whole area. The study was conducted along the Czerwona Woda river – a model stream in the Stołowe Mountains National Park (SW Poland, study area: 91.2 ha) – and an example of coniferous plantations replacing natural broadleaved forest vegetation. Our study revealed the presence of 147 bryophyte species. The most valuable habitats in terms of diversity of bryophyte assemblages were remnants of the natural vegetation – broadleaved forests and streams. These habitats, constituting <5% of the study area, hosted ca 40% of the total species pool (61 and 62 species, respectively), while the species pool of Picea abies forests (92 species) was proportional to cover of this habitat type (ca 60%). Remnants of natural vegetation were hotspots of bryophyte diversity within the heavily altered landscape, and may play a future role as sources of recolonization by forest specialists. Our study also confirmed the important role of riparian areas in maintaining bryophyte species diversity at the landscape scale. The river valley studied contributes >20-fold more to the bryophyte species pool of the whole national park than indicated by its size. Thus, river valleys require special treatment – conservation based on natural restoration, and should remain reserved from wood production, as areas providing a wide range of ecosystem services.
... A permanent excess of water creates favourable conditions for the accumulation of organic matter and development of dome-shaped bogs, typical for the headwater areas. Paludification of the area is conducive to the development of the rich diversity of plant species [Décamps et al. 2004, Osadowski 2006, Pielech et al. 2015. The studies carried out so far indicate that some species of plants occurring within the mid-forest headwater niches have a high capacity for accumulation of macro-and micronutrients [Maine et al. 2006, Hazlett et al. 2008, Parzych et al. 2017, Parzych and Jonczak 2018. ...
The research was done in the upper course of Kamienna Creek which is the left side tributary of River Słupia situated in the northern part of Poland within Leśny Dwór Forest Inspectorate area. The aim of the study was the comparison of accumulation properties of herbaceous plants in spring niches in relation to macro- and microelements. The shoots of research plant species showed a good supply of macro- and micronutrients. The highest values of nutrients were found in the shoots of Athyrium filix-femina (Ni), Caltha palustris (Mg, Ca, Sr), Cardamine amara (K, Zn, Fe, Al), Carex rostrata (Mn) and Solanum dulcamara (N, P, Cu), and the lowest in shoots of Ajuga reptans (P, Zn, Mn), Cardamine amara (N, Cu) and Carex rostrata (K, Mg, Ca, Sr, Ni, Fe, Al). Herbaceous plants accumulated from 1767.23 mmolc.kg-1 (Carex rostrata) to 2739.87 mmolc.kg-1 (Caltha palustris) of all the analyzed elements. Macronutrients dominated in all herbaceous plant species (>99%), and microelements ranged from 0.33% in Solanum dulcamara to 0.67% in shoots Cardamine amara. The share of nitrogen was from 38.8% to 56.8% of this amount, phosphorus from 2.9% to 3.9%, potassium from 28.5% to 40.6%, magnesium from 4.8% to 7.6%, and calcium from 4.6% to 16.4%. A large share of iron (from 33.7% Athyrium filix-femina to 39.5% Caltha palustris), manganese (from 9.2% Cardamine amara to 28.8% Carex rostrata) and aluminum (from 16.7% Carex rostrata to 40.8% Cardamine amara) in total measured components indicates excessive downloading them through plants. During the three years of research done in spring niches, it was found that some plant species take up nutrients in the quantities exceeding their physiological demand, which enables to use some of them for forming e.g. artificial wetlands, stopping many impurities and forming protective barriers.
Keywords: riparian forest, peatbogs, herbaceous plants, nutrients, accumulation
... Water in the initial stream stages exhibited higher electrolytic conductivity and lower dissolved oxygen content than river water. The obtained electrolytic conductivity values are indicative of low or medium mineralisation of waters, which underwent modification along the course of the streams due to contact with the diverse riparian vegetation (Pielech et al., 2015). The recorded dissolved oxygen levels were derived almost exclusively from the atmosphere, with the contact surface between water and atmosphere increasing together with gradual oxygenation as a result of water mixing (Joshi & Kothyari 2003). ...
A study investigating the spatial and temporal variation of physiochemical parameters in
headwater streams was performed over a period of 12 months in the catchment of the Kamienna Creek (northern Poland). Water samples were collected in monthly cycles along three streams (in their upper, middle and lower sections) flowing through the riparian forest, as well as from the Kamienna Creek. In the collected samples, parameters including temperature, pH, electrolytic conductivity, concentration of dissolved oxygen and K+, Na+, Ca2+, Mg2+, NH4+, HCO3-, Cl-, NO3-, PO43- and SO42- ions were determined. The collected water samples were characterised by a neutral or slightly basic pH (6.6-8.9), as well as considerable variation in average electrolytic conductivity, with values ranging between 213 and 544 µS.cm-3 in streams and between 114 and 366 µS.cm-3 in the creek. In general, waters were characterised by low concentrations of dissolved compounds, with a predominance of HCO3- and Ca2+. The waters in both the streams and the creek are calcium-bicarbonate type and are characterised by low
seasonal variability, with season having no influence on concentrations of Ca2+, Mg2+ and HCO3-, nor on conductivity, hardness and mineralisation. However, spatial variation in the chemical composition of waters was observed. Based on data analysis it was found that whereas the waters of the Kamienna Creek were dominated by Ca2+/Mg2+ and HCO3-, those the water of streams were characterised by moderate and low concentrations of calcium, magnesium and hydrocarbonate ions.
... TWI has been frequently tested with measured SM and other soil properties, revealing high correlations (McKenzie and Ryan, 1999;Güntner et al., 1999;Western et al., 1999;Chaplot and Walter, 2003;Zhu et al., 2014). Further, it has been applied in ecological studies devoted to vegetation (Moeslund et al., 2013b;Buchanan et al., 2014;Pielech et al., 2015;Alexander et al., 2016). TWI quantifies the tendency of soil water distribution, which is affected by topography. ...
Topography is an important determinant of soil moisture (SM) distribution and thus drives the functioning of terrestrial ecosystems, including vegetation composition and structure. To assess soil water spatial variability, a number of indices have been used. In this study, we compared the ability of the topographic wetness index (TWI) and Ellenberg’s indicator values (EIV) for moisture to explain the spatial variation of SM in central European forests. Further, we tested the potential heat load (HL) and soil water capacity (SWC) as additional factors that could improve the regressions between TWI and SM as well as EIV and SM. TWI was calculated using 10 different flow routing algorithms. The average EIV for moisture was calculated on the basis of the presence/absence of plant species. We observed that the flow routing algorithms explain SM variability better than the average EIV. The strongest relationship between TWI and SM was obtained by the MFD-md algorithm. The inclusion of SWC increased the explanatory power of both TWI and EIV. On the other hand, HL did not improve the regressions. The relative increase in the explanatory ability by SWC was particularly pronounced in case of EIV. We interpreted this to be a result of the fact that EIV reflect the synergistic effect of multiple environmental gradients on plant distribution. TWI calculated by any of the flow routing algorithms remains a better explanatory factor of SM than EIV, even if the latter was enhanced by the addition of SWC.
... Moisture correlated strongly only with light (r s = 0.67) whose effect is well-known in shaping of species composition within forest ecosystems due to asymmetric light competition between forest overstorey (canopy trees) and herb-layer vegetation. Dynamic and less stable waterlogged soil substrates promote existence of treefall gaps, which increase light transmission through the forest overstorey and in turn modify plant community assembly in floodplain forests (e.g., PIELECH et al. 2015). ...
Vegetation patterns of floodplain forests are highly variable across different habitats in European re-gions. Their plant communities have been well described from the phytosociological point of view, but plant species richness and composition patterns and their underlying environmental factors are still insufficiently known. Sixty-one vegetation plots of black alder-dominated floodplain forests were sampled in central Slovakia in order to find main environmental predictors affecting floristic diversity of their vegetation. For each vegetation plot with a constant size (400 m2), vascular plant species and a set of topographic, climatic, soil physical and chemical characteristics were recorded. A generalized linear model was applied to explain relevance of environmental factors on changes of species richness, whereas the relationship between species composition and explanatory variables was tested using ordination methods. Main gradients of species compositional variation were soil moisture, light, eleva-tion and soil chemistry-related variables. Vascular species richness of plots varied between 19 and 59 (mean 38). Herb-layer species richness was positively related to the soil pH, stream power index and negatively to the concentration of soil iron. These linear trends were accompanied by a hump-shaped response to sand content and a U-shaped response to elevation.
... Riparian forests are also some of the ecosystems that are most sensitive to human influences and most threatened (Schinegger et al. 2012;Greet et al. 2013). Thus, understanding the relationships between the physical features of the environment and vegetation is a great challenge and may help to develop scientific knowledge to enhance riparian restoration projects (Pielech et al. 2015). ...
In order to protect and understand the regeneration of riparian forests, it is important to understand the environmental conditions that lead to their vegetation differentiation. We evaluated the structure, composition, density and regeneration of woody species in forests along the river Safaroud in Ramsar forest in northern Iran in relation to elevation, soil properties and distance from the river. Using 60 transects located perpendicularly to river and 300 quadrats, we examined forests 0, 50, 100, 150 and 200 m from the stream along an elevation gradient spanning from 350 to 2,400 m a.s.l. We found that total density, regeneration, diameter and basal area of trees were significantly higher in the interior of the forest whereas shrub density was higher close to the river. The uneven-aged forest structure showed no significant differences among gradient from the river to the forest interior. Hydro-geomorphic processes, flooding, the elevation gradient, distance from the river and soil properties were the most important factors that influenced plant community distribution in relation to the river.
... Hors ak, 2006;H ajek et al., 2007;Hors ak et al., 2015), only little is known about forest spring-fed areas, though they represent a contrasting type of spring habitats. Several studies dealt with the vegetation of acid springs (Strohbach et al., 2009;Schweiger and Beierkuhnlein, 2014), showing that the vegetation of spring-fed areas is mainly controlled by local conditions (Pielech et al., 2015), and is more species rich than the other riparian forest habitats (Kuglerov a et al., 2014). However, we have only very limited data on soil-dwelling invertebrates such as molluscs, although they are likely to develop species rich assemblages in spring-fed forest habitats, mainly in the calcareous types (Hors ak, 2006). ...
Land-snail species richness has repeatedly been found to increase with the increasing site calcium content and humidity. These two factors, reported as the main drivers of land-snail assemblage diversity, are also among the main habitat characteristics of calcareous seepages. Here we explore local species richness and compositional variation of forest spring-fed patches (i.e. seepages), to test the hypothesis that these habitats might act as biodiversity hotspots and refugia of regional snail faunas. In contrast to treeless spring fens, only little is known about land snail faunas inhabiting forest seepages. Studying 25 isolated calcareous forest seepages, evenly distributed across the White Carpathians Protected Landscape Area (SE Czech Republic), we found that these sites, albeit spatially very limited, can harbour up to 66% of the shelled land-snail species known to occur in this well-explored protected area (in total 83 species). By comparing land snail assemblages of the studied seepages with those occurring in the woodland surroundings of each site as well as those previously sampled in 28 preserved forest sites within the study area, we found the seepages to be among the most species rich sites. Although the numbers of species did not statistically differ among these three systems, we found highly significant differences in species composition. Seepage faunas were composed of many species significantly associated with spring sites, in contrast to the assemblages of both surrounding and preserved forest sites. Our results highly support the hypothesis that calcareous forest seepages might serve as refugia and biodiversity hotspots of regional land snail faunas. Protection of these unique habitats challenges both conservation plans and forest management guidelines as they might act as sources for the recolonization and restoration of forest snail assemblages particularly in areas impoverished by harvesting and clearcutting.
... In many regions, the native flora contribute to fulfill numerous stream ecosystem functions such as water quality enhancement, flood and erosion control, bank stability, wildlife uses, and in-stream root habitat (Sweeney et al., 2004;Boggs et al., 2016;Witt et al., 2016). As a result, there has been a strong push to protect riparian ecosystems from disturbances such as harvesting or development, through the use of buffers (Pielech et al., 2015;Cristan et al., 2016;Schilling, 2016). However, the boundaries of riparian areas are often hard to define and it can be difficult to determine acceptable buffer widths (Holmes and Goebel, 2011;Kuglerová et al., 2014), particularly for headwater streams (Alexander et al., 2007;Clinton et al., 2010). ...
In mountainous areas such as the southern Appalachians USA, riparian zones are difficult to define. Vegetation is a commonly used riparian indicator and plays a key role in protecting water resources, but adequate knowledge of floristic responses to riparian disturbances is lacking. Our objective was to quantify changes in stand-level floristic diversity of riparian plant communities before (2004) and two, three, and seven years after shelterwood harvest using highlead cable-yarding and with differing no-cut buffer widths of 0 m, 10 m, and 30 m distance from the stream edge. An unharvested reference stand was also studied for comparison. We examined: (1) differences among treatment sites using a mixed linear model with repeated measures; (2) multivariate relationships between ground-layer species composition and environmental variables (soil water content, light transmittance, tree basal area, shrub density, and distance from stream) using nonmetric multidimensional scaling; and (3) changes in species composition over time using a multi-response permutation procedure. We hypothesized that vegetation responses (i.e., changes in density, species composition, and diversity across the hillslope) will be greatest on harvest sites with an intermediate buffer width (10-m buffer) compared to more extreme (0-m buffer) and less extreme (30-m buffer and no-harvest reference) disturbance intensities. Harvesting initially reduced overstory density and basal area by 83% and 65%, respectively, in the 0-m buffer site; reduced by 50% and 74% in the 10-m buffer site; and reduced by 45% and 29% in the 30-m buffer site. Both the 0-m and 10-m buffer sites showed increased incident light variability across the hillslope after harvesting; whereas, there was no change in the 30-m and reference sites over time. We found significant changes in midstory and ground-layer vegetation in response to harvesting with the greatest responses on the 10-m buffer site, supporting our hypotheses that responses will be greatest on sites with intermediate disturbance. Ground-layer species composition differed significantly over time in the 0-m buffer and 10-m buffer sites (both P < 0.0001), but did not change in the 30-m buffer and reference sites (both P > 0.100). Average compositional dissimilarity increased after seven years, indicating greater within-stand heterogeneity (species diversity) after harvesting. These vegetation recovery patterns provide useful information for evaluating management options in riparian zones in the southern Appalachians.
... Mountain ecological systems are unique, have the feature of vulnerability and exhibit sensitivity to external forces and susceptibility to mountain disasters [35][36]. However, mountain eco-security early warning research is very limited overseas, and domestically the common research topic is mountain city ecological security evaluation [1,37], mountain hazards monitoring and management [38][39][40], the sustainable development of mountain social ecosystems [41][42], mountain grassland characteristics and threats research [43][44], mountain forest ecosystem species distribution and composition, disaster prevention and management research [45][46][47][48], and mountain soil research [49], etc. ...
At present, overseas and domestic eco-security early warning research is in the exploratory stage. This paper uses Kizilsu Kirghiz Autonomous Prefecture as the research object and constructs an evaluation index system based on the pressure-state-response (P-S-R) conceptual model. This study analyzes eco-security early warning in the study area using the granger causality test model, the entropy weight method, and the matter-element model, and analyzes the present eco-security situation and future development trends in the study area. The author hopes that this study can further enrich eco-security early warning research and provide a scientific reference for ecological security in the study area. The specific research results were as follows: 1) This article evaluated the plateau mountain ecological security early warning system, and the application of the Granger causality test was further implemented with targeted and objective index system selection, achieving a one-to-one analysis in the results and further enriching the research theory of the importance of eco-security early warning systems. 2) On the whole, the eco-security situation in the study area is gradually moving in a positive direction, but the low level of overall eco-security continues to cause great pressure. 3) From 2005 to 2014, the study area gradually attached greater importance to the construction of ecosecurity, but the overall eco-security level is low, and the overall eco-security regulation capacity is insufficient. 4) The key eco-security pressure in the study area mainly derives from industrial and agricultural development, although the control power is gradually increasing, but the control effect is not obvious, and the contradiction between ecological security and socio-economic development is still very obvious. 5) The study area is a typical earthquake-prone area, and financial input into the governance of natural geological disasters due to the high frequency of earthquakes is gradually increasing; but the study area still needs to increase its investments.
... Therefore, to improve and restore the fragile ecological system in an opencast coal mine dump located in a loess area, the co-evolution of both vegetation and soil should be considered 20 . Effective management and conservation, particularly through approaches based on the emulation of natural disturbances, should take these differences into consideration by developing site-specific management guidelines for vegetation 36 . A key strategy for ecological restoration in an opencast coal mine dump located in a loess area involves improvements in soil conditions and increases in the area of artificial vegetation. ...
Vegetation plays an important role in improving and restoring fragile ecological environments. In the Antaibao opencast coal mine, located in a loess area, the eco-environment has been substantially disturbed by mining activities, and the relationship between the vegetation and environmental factors is not very clear. Therefore, it is crucial to understand the effects of soil and topographic factors on vegetation restoration to improve the fragile ecosystems of damaged land. An investigation of the soil, topography and vegetation in 50 reclamation sample plots in Shanxi Pingshuo Antaibao opencast coal mine dumps was performed. Statistical analyses in this study included one-way ANOVA and significance testing using SPSS 20.0, and multivariate techniques of detrended correspondence analysis (DCA) and redundancy analysis (RDA) using CANOCO 4.5. The RDA revealed the environmental factors that affected vegetation restoration. Various vegetation and soil variables were significantly correlated. The available K and rock content were good explanatory variables, and they were positively correlated with tree volume. The effects of the soil factors on vegetation restoration were higher than those of the topographic factors.
Aim
A resource based conceptual model of plant diversity (RBCM) assumes direct relationships between resource supply and the diversity of a local plant assembly. However, the RBCM largely ignores variation in soil toxicity imposed by climatic effects. Both soil limiting resources and soil toxicity vary along climatic gradients but their net and interactive effects on plant species diversity remain unknown. We asked how climatic gradients shape resource availability, soil toxicity and dominance of herb‐layer graminoids, and how these predictors control local species diversity of herbs and bryophytes.
Location
Swamp forests, Central Europe.
Taxon
Vascular plants, bryophytes.
Methods
Alpha taxonomic diversity of vascular plants and bryophytes was counted for 101 vegetation plots sampled in temperate swamp forests distributed along an 800‐km geographical gradient across the Continental, Alpine and Pannonian biogeographical regions. Path analysis (structural equation modelling) was used to quantify the direct and indirect effects of climatic variable (potential evapotranspiration; PET), limiting resources (soil N/P, Ca, C/N, proxies for light and water availability) and soil toxicity (Mn) on graminoid dominance and community diversity.
Results
PET negatively influenced species richness of both groups analysed either directly or indirectly through its positive effect on the cover of graminoid species. Alpha diversity of herbs was additionally reduced by soil toxicity (Mn). Limiting resources correlated either with species dominance (canopy shading, soil Ca) or with PET (soil N/P ratio), but they did not control species richness pattern.
Main Conclusions
Climate, soil toxicity and species dominance determined alpha diversity instead of the expected importance of soil limiting resources. These results are key to advancing the theoretical framework of the RBCM. Increased soil toxicity (Mn) in well‐watered regions favours the dominance of plant competitors at the expense of less tolerant species. This implies a potential threat to wetland diversity under ongoing climate change.
One of the important issues in plant autecology is the analysis and understanding of species-environment relationships and response of species to ecological gradients. Understanding how species respond to environmental variables is useful for predicting the environmental and geographic distribution of species. The main objective of this research is to study the response curve of European yew to identify the most important climatic and physiographic gradient in the northern forests of Iran. In the present study the Huisman–Olff–Fresco function (HOF) was used to study the response curve of the European yew in relation to each of the environmental variables individually and extract the optimum values. In order to select the optimal model, the Akaike Information Criterion (AIC) was used. Based on the results of this study, 41% of the models have either monotonically increasing or decreasing behaviors (models 2 and 3), 27% of the models have a unimodal symmetric behavior and 32% of models have a skewed behavior. European yew in 59% of models has a unimodal response curve. Based on the variables used in the study, it can be said that the European yew is a species that prefers oceanic climates, midlands altitudes, and north-facing slopes for establishment in temperate forests of Iran. Together, these findings advance niche theory about the European yew tree and may be used for generating better predictive models of European yew distributions under future climate change.
We evaluated trends in fish habitat condition and their relationship to natural and management associated disturbances in forests of coastal Southeast Alaska. Monitoring data spanning 9–19 years (1994–2012) from 14 stream reaches were examined using linear mixed effects models to evaluate patterns and trends in fish habitat condition. Modeling detected multiple patterns of habitat change that include postharvest pulses in large wood (LW) recruitment and reductions in substrate particle size; both followed by long term trends (average LW density increased 0.8–0.9 pieces/year and median substrate particle size decreased 0.6–1.3 mm/year) that were observed up to two decades after harvest. Trends in spawning gravel followed patterns of change in substrate except at higher gradient cobble-dominated reaches where the reduction in substrate particle size improved spawning habitat. Trends in pool habitat were not detectable over the short-term for most attributes, but exhibited gradual changes after harvest that became strongly evident over the long-term (average residual pool depth increased 0.5 cm/year, wood-formed pools increased 0.9%/year). The changes in habitat conditions and correlations with riparian forest attributes (buffer strip length and wind exposure) suggest that the habitat responses were related to increased tree windthrow after timber harvest. Furthermore, the degree to which LW recruits function in forming pools appears to influence long term trends in stream habitat. We observed that only 26% of new LW recruits, on average, were functioning and that wood function increased over time; peaking (72% of recruits functioned to form habitat) about three decades after recruitment. Our monitoring over two decades enabled us to discern slow evolving trends, showed how trends in pool habitat not initially evident may be associated with buffer disturbances (windthrow, landslides), and demonstrated the long-term consequences of management actions.
Received 02 Aug 2016 accepted 05 May 2017 revised 06 Apr 2017
Row-crop agriculture, continuous-grazing, and stream channelization, have accelerated stream bank erosion and increased sediment load. Stream bank erosion rates and total soil loss were compared among riparian forest buffers, row-crop fields and continuously grazed pastures along a continuous 11 km (6.8 mi) stream reach in central Iowa. Exposed erosion pins were measured to estimate stream bank erosion rates, approximately every month from June 1998 to June 1999, except during the winter months. Total stream bank soil losses for each treatment were estimated from the mean bank erosion rate, mean bulk density, and the total stream bank eroding area. Row-crop fields had the greatest stream bank erosion rate and total soil losses followed by continuously grazed pastures while riparian forest buffers had the lowest. If riparian forest buffers had been established along all of the non-buffered segments of the 11 km (6.8 mi) stream reach, total stream bank soil loss would have been reduced by approximately 72%.
The flood pulse concept (FPC), published in 1989, was based on the scientific experience of the authors and published data worldwide. Since then, knowledge on floodplains has increased considerably, creating a large database for testing the predictions of the concept. The FPC has proved to be an integrative approach for studying highly diverse and complex ecological processes in river-floodplain systems; however, the concept has been modified, extended and restricted by several authors. Major advances have been achieved through detailed studies on the effects of hydrology and hydrochemistry, climate, paleoclimate, biogeography, biodiversity and landscape ecology and also through wetland restoration and sustainable management of flood-plains in different latitudes and continents. Discussions on floodplain ecology and management are greatly influenced by data obtained on flow pulses and connectivity, the Riverine Productivity Model and the Multiple Use Concept. This paper summarizes the predictions of the FPC, evaluates their value in the light of recent data and new concepts and discusses further developments in floodplain theory.
Suitable thermal conditions in streams are necessary for fish and predictions of future climate changes infer that water temperatures may regularly exceed tolerable ranges for key species. Riparian woodland is considered as a possible management tool for moderating future thermal conditions in streams for the benefit of fish communities. The spatial and temporal variation of stream water temperature was therefore investigated over 3 years in lowland rivers in the New Forest (southern England) to establish the suitability of the thermal regime for fish in relation to riparian shade in a warm water system. Riparian shade was found to have a marked influence on stream water temperature, particularly in terms of moderating diel temperature variation and limiting the number of days per year that maximum temperatures exceeded published thermal thresholds for brown trout. Expansion of riparian woodland offers potential to prevent water temperature exceeding incipient lethal limits for brown trout and other fish species. A relatively low level of shade (20–40%) was found to be effective in keeping summer temperatures below the incipient lethal limit for brown trout, but ca. 80% shade generally prevented water temperatures exceeding the range reported for optimum growth of brown trout. Higher levels of shade are likely to be necessary to protect temperature-sensitive species from climate warming. © Crown copyright 2010.
The Cocktail method was applied to a small data set derived in a regional survey on riparian forest in the Polish part of the Sudetes. Formalised classification revealed the occurrence of seven associations. Considering the ecological character, three distinct groups emerged among them: i) alluvial forests (Salicetum albae, Alnetum incanae), ii) forests of small and medium mountain streams with only a narrow riparian zone (Salicetum fragilis, Stellario nemorum-Alnetum glutinosae and Fraxino-Alnetum) and iii) forests developed on waterlogged soils of spring-fed areas (Carici remotae-Fraxinetum and Piceo-Alnetum). The associations Salicetum fragilis and Piceo-Alnetum are reported for the first time from Poland. Analysis of GIS-derived environmental variables showed that average altitude, stream power index (SPI) and river order were significantly different among the associations, while there were no differences among average values of slope, solar radiation and topographic wetness index (TWI). Significant differences in species richness among the associations were also identified. Application of the Cocktail method in regional studies was also discussed.
Riparian corridors possess an unusually diverse array of species and environmental processes. This @'ecological@' diversity is related to variable flood regimes, geomorphic channel processes, altitudinal climate shifts, and upland influences on the fluvial corridor. This dynamic environment results in a variety of life history strategies, and a diversity of biogeochemical cycles and rates, as organisms adapt to disturbance regimes over broad spatio-temporal scales. These facts suggest that effective riparian management could ameliorate many ecological issues related to land use and environmental quality. We contend that riparian corridors should play an essential role in water and landscape planning, in the restoration of aquatic systems, and in catalyzing institutional and societal cooperation for these efforts.
Data on canopy trees (stems ≥ 15 cm DBH) in riparian wetlands, spanning from headwaters to large river floodplains, were used to test whether forest canopy composition differed among hydrogeomorphic (HGM) riverine subclasses and among physiographic sub-regions (Major Land Resource Areas; MLRA) within a given HGM subclass. Riverine stands (n = 225) were sampled in four MLRA regions of the Southeastern U.S. Atlantic and Gulf Coastal Plain Physiographic Provinces. Composition data were analyzed using Non-metric Multidimensional Scaling and Multiple-Response Permutation Procedures to evaluate differences among HGM subclasses and MLRA regions. Analyses showed that canopy composition differed among three a priori subclasses related to Strahler stream order: headwater complex (along 1st-3rd order streams), mid-gradient floodplain (4th-6th order), and low-gradient floodplain (> 6th order). Further, composition also differed by MLRA region within each subclass. Thus, not only was species composition related to riverine hydrogeomorphology across a wide physiographic area, but differences in composition within HGM subclasses were also related to sub-region. These data could be useful in defining floristic reference standards when evaluating floodplain condition in southeastern USA Coastal Plain stream networks.
Driving with forestry machines on wet soils within and near stream and lake buffers can cause soil disturbances, i.e. rutting and compaction. This - in turn - can lead to increased surface flow, thereby facilitating the leaking of unwanted substances into downstream environments. Wet soils in mires, near streams and lakes have particularly low bearing capacity and are more susceptible to rutting. It is important to model and map the extent of these areas and associated wetness variations. This can be done with adequate reliability using high resolution digital elevation model (DEM). In this article, we report on several digital terrain indices to predict soil wetness by wet-area locations. We varied the resolution of these indices to test what scale produces the best possible wet-areas mapping conformance. We found that topographic wetness index (TWI) and the newly developed cartographic depth-to-water index (DTW) were the best soil wetness predictors. While the TWI derivations were sensitive to scale, the DTW derivations were not and were therefore numerically fairly robust. Since the DTW derivations vary by the area threshold used for setting stream flow initiation we found that the optimal threshold values varied by landform, e.g., 1-2 ha for till-derived landforms vs. 8 -16 ha for a coarse-textured alluvial floodplain.
Riparian vegetation research has traditionally focused on channel-related processes because riparian areas are situated on the edge of aquatic ecosystems and are therefore greatly affected by the flow regime of streams and rivers. However, due to their low topographic position in the landscape, riparian areas receive significant inputs of water and nutrients from uplands. These inputs may be important for riparian vegetation, but their role for riparian plant diversity is poorly known. We studied the relationship between the influx of groundwater (GW) from upland areas and riparian plant diversity and composition along a stream size gradient, ranging from small basins lacking permanent streams to a seventh-order river in northern Sweden. We selected riparian sites with and without GW discharge using a hydrological model describing GW flow accumulation to test the hypothesis that riparian sites with GW discharge harbor plant communities with higher species richness. We further investigated several environmental factors to detect habitat differences between sites differing in GW discharge conditions. Vascular plant species richness was between 15% and 20% higher, depending on the spatial scale sampled, at riparian sites with GW discharge in comparison to non-discharge sites, a pattern that was consistent across all stream sizes. The elevated species richness was best explained by higher soil pH and higher nitrogen availability (manifested as lower soil C/N ratio), conditions which were positively correlated with GW discharge. Base cations and possibly nitrogen transported by groundwater may therefore act as a terrestrial subsidy of riparian vegetation. The stable isotopes 15N and 13C were depleted in soils from GW discharge compared to non-discharge sites, suggesting that GW inputs might also affect nitrogen and carbon dynamics in riparian soils. Despite the fact that many flows of water and nutrients reaching streams are filtered through riparian zones, the importance of these flows for riparian vegetation has not been appreciated. Our results demonstrated strong relationships between GW discharge, plant species richness and environmental conditions across the entire stream size gradient, suggesting that both river hydrology and upland inputs should be considered to fully understand riparian vegetation dynamics.
In addition, during the program, several influential seminars led participants in Poland, and this publication in the Polish Journal of Ecology is symbolic of exceptional opportunities of links developed between researchers from the 24 participating countries. On the whole, 22 research projects were organised, and about 20 seminars were attended by more than 2,000 researchers. In this perspective, the ecotone project of UNESCO may appear as a joint venture similar to what we urgently need today if ecological research is to contribute to the edification of a more sustainable world. ABSTRACT: Riparian zones are well known for their inherent ecological properties related to biogeochemical cycles, biodiversity, and catchment management. The international MAB/UNESCO programme which was running between 1988 and 1998 was related to the land/water ecotones, mainly riparian zones. This article, inspired by this programme – seeks to highlight the role of riparian processes on biogeochemical cycles and biodiversity under different climatic conditions. Their role is investigated by focusing on: i) the lateral eco-tone between land and water systems, ii) their longitudinal corridor structure and, iii) the dry-wet cycles. This information is then used to suggest the value of riparian zones in landscape management. We emphasize the key roles of the ecotonal structure, longitudinal connectivi-ty and timing of the occurrence of wet-dry cycles for riparian zones to process nitrate fluxes and to maintain high levels of biodiversity at the landscape scale. In the context of the worldwide transformations of flow regimes, the deterioration of water quality and loss of biodiversity , restoring riparian zones is both a key objective and a formidable challenge that implies envisioning the consequences of management actions on the long term, considering entire river basins, and paying attention to other environmental , regional and global changes.
Running water ecosystems of Europe are affected by various human pressures. However, little is known about the prevalence, spatial patterns, interactions with natural environment and co-occurrence of pressures. This study represents the first high-resolution data analysis of human pressures at the European scale, where important pressure criteria for 9330 sampling sites in 14 European countries were analysed. We identified 15 criteria describing major anthropogenic degradation and combined these into a global pressure index by taking additive effects of multiple pressures into account. Rivers are affected by alterations of water quality (59%), hydrology (41%) and morphology (38%). Connectivity is disrupted at the catchment level in 85% and 35% at the river segment level. Approximately 31% of all sites are affected by one, 29% by two, 28% by three and 12% by four pressure groups; only 21% are unaffected. In total, 47% of the sites are multi-impacted. Approximately 90% of lowland rivers are impacted by a combination of all four pressure groups.
Emulation of natural disturbance (END) is an emerging paradigm for modern, ecosystem-based forest management in North America. On the premise that periodic disturbance is an integral part of natural, determinative processes on forest landscapes, managing forests by emulating natural disturbance is thought to produce landscape patterns that resemble those arising from natural disturbances and that are known to maintain critical processes and habitat for conserving biodiversity. Applying END principles to forest watersheds has implications for the protection of aquatic ecosystems because END can include intentional logging disturbance near water to emulate natural riparian disturbance. Literature shows that logging in watersheds, and especially in riparian areas, can lead to negative abiotic and biotic effects in aquatic ecosystems. However, an integration of the current understanding of land–water linkages in forest watersheds with general disturbance ecology would suggest that periodic watershed and riparian disturbances may be natural renewal processes that are required for long-term sustainability of aquatic ecosystems. Previous syntheses of END in forestry failed to consider the implications for aquatic ecosystems, and most forest-management guidelines default to the protection of water resources by systematic riparian (shoreline) buffers. This paper introduces the concepts of END and provides a theoretical basis for using intentional riparian forest disturbance to sustain aquatic habitat complexity and ecosystem integrity.
Designing management strategies based on the emulation of natural disturbance (END) to promote long-term sustainability of riparian forests and their adjacent aquatic ecosystems is an evolving process. Conceptually, the goal of END in riparian forest management is to mimic, to the extent possible, natural disturbance processes within the range of natural variability of the ecosystem while accounting for both temporal (frequency) and spatial (size) scales of the disturbance. The application of END in riparian forests has been evaluated in a limited but growing number of studies. From these studies, the idea has emerged that END could be used as a tool to enhance forest complexity and resilience capacity through carefully implemented management strategies. In practice, however, this tool presents a formidable challenge, constrained by scientific and social uncertainty. In this BRIDGES cluster we have critically examined: 1) the historical, scientific, and practical foundations of applying END in riparian forest management as an alternative to fixed-width buffers, and 2) the extent to which mimicking natural disturbance and renewal processes can protect aquatic ecosystems through conservation of riparian and aquatic biodiversity. In this synthesis paper, we identify some of the outstanding questions and uncertainties that constrain the integration of END into riparian forest management, provide some initial guiding principles for applying END in riparian areas, and offer recommendations for future research.
The standard textbook of Vegetation Ecology. A reprint (2002) is available from The Blackburn Press, Caldwell, New Jersey.
Stream water dissolved organic carbon (DOC) correlates positively with soil organic carbon (SOC) in many biomes. Does this relationship hold in a small geographic region when variations of temperature, precipitation and vegetation are driven by a significant altitudinal gradient? We examined the spatial connectivity between concentrations of DOC in headwater stream and contents of riparian SOC and water-soluble soil organic carbon (WSOC), riparian soil C:N ratio, and temperature in four vegetation types along an altitudinal gradient in the Wuyi Mountains, China. Our analyses showed that annual mean concentrations of headwater stream DOC were lower in alpine meadow (AM) than in subtropical evergreen broadleaf forest (EBF), coniferous forest (CF), and subalpine dwarf forest (SDF). Headwater stream DOC concentrations were negatively correlated with riparian SOC as well as WSOC contents, and were unrelated to riparian soil C:N ratio. Our findings suggest that DOC concentrations in headwater streams are affected by different factors at regional and local scales. The dilution effect of higher precipitation and adsorption of soil DOC to higher soil clay plus silt content at higher elevation may play an important role in causing lower DOC concentrations in AM stream of the Wuyi Mountains. Our results suggest that upscaling and downscaling of the drivers of DOC export from forested watersheds when exploring the response of carbon flux to climatic change or other drivers must done with caution.
Groundwater flowing from hillslopes through riparian (near-stream) soils
often undergoes chemical transformations that can substantially
influence stream water chemistry. We used landscape analysis to predict
total organic carbon (TOC) concentration profiles and groundwater levels
measured in the riparian zone (RZ) of a 67 km2 catchment in
Sweden. TOC exported laterally from 13 riparian soil profiles was then
estimated based on the riparian flow-concentration integration model
(RIM). Much of the observed spatial variability of riparian TOC
concentrations in this system could be predicted from groundwater levels
and the topographic wetness index (TWI). Organic riparian peat soils in
forested areas emerged as hotspots exporting large amounts of TOC. These
TOC fluxes were subject to considerable temporal variations caused by a
combination of variable flow conditions and changing soil water TOC
concentrations. Mineral riparian gley soils, on the other hand, were
related to rather small TOC export rates and were characterized by
relatively time-invariant TOC concentration profiles. Organic and
mineral soils in RZs constitute a heterogeneous landscape mosaic that
potentially controls much of the spatial variability of stream water
TOC. We developed an empirical regression model based on the TWI to move
beyond the plot scale and to predict spatially variable riparian TOC
concentration profiles for RZs underlain by glacial till.
Land use changes have resulted in large deforestation of rural landscapes, thus influencing transport of water and materials along the watersheds. Riparian zones have strong effects on stream water quality, but most studies evaluated the effects of riparian vegetation (forested vs. deforested), although riparian forests may greatly differ in structure. Here we evaluated the effects of riparian vegetation characteristics (RV) and riparian forest structure (RFS) on stream water quality in a tropical rural landscape in SE Brazil. We sampled 15 low-order streams along a gradient in riparian degradation, from completely deforested streams to those with well-developed riparian forests. In each stream we established a 100 m reach and evaluated RV (trees, grasses, vines, bamboo, canopy closure, and riparian forest width), RFS (tree density and height, vertical canopy structure, mean basal area and diameter at breast height), and stream habitat and water quality (mean water depth, fine sediment cover (FSC), electric conductivity (EC), dissolved oxygen (DO), ammonium, nitrate, total N, dissolved, particulate, and total P). We used Principal Components Analyses to reduce dimensionality of RV and RFS variables, and evaluated the separate effects of RV and RFS on water quality variables using conditional autoregressive models. We found effects of both RV and RFS on FSC, EC, DO and ammonium concentrations, and effects of only RFS on total and dissolved P concentrations. These results suggest that although RV variables are good predictors of the buffering role of riparian zones, the structure of the riparian forest can influence stream water quality variables. Thus, heterogeneity in riparian forest structure due to forest degradation or restoration should be considered when evaluating buffering effects of riparian zones.
This chapter deals with the formulation of how to move how much water into which neighboring cells in order to have a representation of reality that is suitable for a given task. This can be pictured as many drops flowing from one cell to one or more adjacent cells, depending on their relative elevations. The chapter assembles four criteria by which to judge or select a flow direction algorithm: (1) Handling of the discretization into only eight possible adjacent flow directions; (2) handling of divergence; (3) handling of dispersal; and (4) handling of sub-grid effects. It presents the basic types of single- and multiple-neighbor flow algorithms that are fundamentally different. Elevation dominates the movement of water and a multitude of associated phenomena at or close to the land-surface. Because of the wide availability of DEMs, geomorphometric techniques are outstandingly powerful in the quantification, analysis, forecasting, or parameterization of phenomena related to the flow of water on the Earth's surface. However, the choice of methods depends on the task at hand and on the data available. The chapter gives an introduction to the most important concepts in geomorphometry that relate to the flow of water. The methods explained, represent a selection of methods originating from a large and active research community. Catchment area is a powerful parameter of the amount of water draining though a cell that can be combined with other attributes to form compound indices. In the following, we briefly describe the two powerful and frequently used indices: Wetness and stream power.
Riparian (streamside) vegetation may help control transport of sediments and chemicals to stream channels. Studies of a coastal plain agricultural watershed showed that riparian forest ecosystems are excellent nutrient sinks and buffer the nutrient discharge from surrounding agroecosystems. Nutrient uptake and removal by soil and vegetation in the riparian forest ecosystem prevented outputs from agricultural uplands from reaching the stream channel. The riparian ecosystem can apparently serve as both a short- and long-term nutrient filter and sink if trees are harvested periodically to ensure a net uptake of nutrients.
The interface found where rivers meet terrestrial systems is an ecotone that has a profound influence on the movement of water and waterborne contaminants. Maintaining or restoring ecotone functions and characteristics such as natural near stream vegetation and channel morphology are important means to safeguard water quality in agricultural landscapes. A riparian buffer zone of 20 to 30 m width can remove up to 100% of incoming nitrate. Denitrification is the major pathway of removal and rates depend on nitrate loadings, carbon availability, and hydrology. Denitrification occurs throughout the year as long as subsurface hydrology is intact, whereas plant uptake of nitrogen is limited to seasonal removal. Nitrate removal is favored in forested areas with subsurface flow and is less in grassed areas with surface flow. The balance between surface and subsurface flows and the redox conditions that result are critical to nitrate removal in riparian ecotones. Surface retention of nutrients and sediment is a function of slope length and gradient, vegetation density, and flow rates. Plant communities play a major role in nitrogen cycling by acting as a source of carbon for denitrifying bacteria, direct uptake of nutrients, and creating oxidized rhizospheres where nitrification can occur. Restoration of riparian zones requires knowledge of the area's hydrology and ecology, as well as clear goals for the project. Restoration of riparian zones for water quality improvement may provide higher economic benefits than allocating the same land to crops. While it is possible to restore the functions of natural floodplain systems, existing restoration techniques are in their infancy and success cannot be guaranteed, especially given the extent of hydrological modification that has occurred in most developed countries.
The presence of riparian veg- etation is shown to affect both physical and bio- logical properties of headwater streams. Riparian vegetation mediates food resource availability for macroinvertebrates and fish within streams through addition of allochthonous material such as leaves, woody debris and terrestrial inverte- brates. Riparian shade can also reduce biomass and production of autochthonous algae. The potential role of riparian vegetation in enhanc- ing biodiversity and productivity of headwater streams is discussed, with reference to improving salmonid fish stocks in the headwater streams of Ireland and Great Britain.
Groundwater dependent ecosystems (GDEs) include valuable ecosystems such as springs, wetlands, rivers, lakes and lagoons. The protection of these systems and services they provide is highlighted by international agreements, i.e. Ramsar convention on wetlands, and regional legislation, i.e. the European Water Framework Directive. Groundwater provides water, nutrients and a relatively stable temperature. However, the role of groundwater in surface ecosystems is not fully understood. The ecosystem can depend on groundwater directly or indirectly, and the reliance can be continuous, seasonal or occasional. This has implications for the vulnerability of ecosystems, as some may be easily affected by external pressure. Conceptual models and quantitative assessments of how groundwater interacts with the environment are needed. GDEs are also threatened by different land use activities and climate change. Hence, we need to understand how GDEs are affected by changes in groundwater quantity and quality, as severe groundwater changes have been observed in many regions. This study examines key aspects of GDEs (hydrogeology, geochemistry and biodiversity) in order to improve conceptual understanding of the role of groundwater in such ecosystems. The status and baseline of different types of GDEs are discussed, with particular emphasis on past evidence of environmental change and potential thresholds and threats in GDEs in various parts of Europe with different land use, climate and geology.
To explore how high flows limit the streamward extent of riparian vegetation we quantified the effects of sediment mobilization and extended inundation on box elder (Acer negundo) saplings along the cobble-bed Gunnison River in Black Canyon of the Gunnison National Monument, Colorado, USA. We counted and aged box elders in 144 plots of 37.2 m2, and combined a hydraulic model with the hydrologic record to determine the maximum shear stress and number of growing-season days inundated for each plot in each year of the record. We quantified the effects of the two mortality factors by calculating the extreme values survived during the lifetime of trees sampled in 1994 and by recounting box elders in the plots following a high flow in 1995. Both mortality factors can be modeled as threshold functions; box elders are killed either by inundation for more than 85 days during the growing season or by shear stress that exceeds the critical value for mobilization of the underlying sediment particles. Construction of upstream reservoirs in the 1960s and 1970s reduced the proportion of the canyon bottom annually cleared of box elders by high flows. Furthermore, because the dams decreased the magnitude of high flows more than their duration, flow regulation has decreased the importance of sediment mobilization relative to extended inundation. We use the threshold functions and cross-section data to develop a response surface predicting the proportion of the canyon bottom cleared at any combination of flow magnitude and duration. This response surface allows vegetation removal to be incorporated into quantitative multi-objective water management decisions.
The dynamic and hierarchical nature of lotic ecosystems may be conceptualized in a four-dimensional framework. Upstream-downstream interactions constitute the longitudinal dimension. The lateral dimension includes interactions between the channel and riparian/floodplain systems. Significant interactions also occur between the channel and contiguous groundwater, the vertical dimension. The fourth dimension, time, provides the temporal scale. Lotic ecosystems have developed in response to dynamic patterns and processes occurring along these four dimensions. An holistic approach that employs a spatio-temporal framework, and that perceives disturbances as forces disrupting major interactive pathways, should lead to a more complete understanding of the dynamic and hierarchical structure of natural and altered lotic ecosystems.
Publisher Summary
This chapter describes the various geomorphic and hydrologic processes such as catchments that influence riparian system development and maintenance. Catchments are areas of the land surface in which all the runoff drains to a single point on a stream or river channel, and are bounded by drainage divides; catchments have been known to range from hundreds of square meters in size to millions of square kilometers. Catchment drainage networks may have dendritic, palmate dendritic, or trellised forms, depending on the nature of underlying geology. These networks vary in drainage density and gradient, which affect riparia by impacting flood intensity and stream power, respectively. The most basic geomorphic processes in catchments are erosion, transport, and deposition. These processes operate across all time and space scales but vary in relative importance along drainage networks. Erosive processes dominate headwater regions, whereas deposition processes dominate the bottom of catchments draining to the ocean or into enclosed basins. Transport dominates in the mid-reaches of river systems. Erosion scours and eliminates riparian habitats and occurs when the shear stress imposed by flowing water exceeds the shear strength of the material over which it flows. The dominant forms of erosion include down-cutting and lateral movement of channels and scouring of channels and floodplains. Hydrologic processes strongly influence riparian habitats as the transport medium for sediments, but the presence or absence of water by itself is also an important control on riparian form and function. Flooding is a key process that distributes surface water to riparian environments and sets up gradients that drive surface water-groundwater exchanges. Four characteristics of floods, which are especially important to riparian and floodplain ecosystems are magnitude, frequency, timing, and duration.
Natural flow regimes are important for sustaining riverine vegetation. The regulation of river flows to provide water for agriculture often results in changes to flow timing. This study assesses the impact of altered seasonal flow patterns on riverine flora.
Within temperate Australia, we surveyed the vegetation of five lowland rivers, three of which have large dams that alter their seasonal flow patterns; the other two are unregulated. From four to six sites were selected on each river, and these were classified into three levels of regulation based on the extent to which the timing of their seasonal flow patterns were altered. Sites were surveyed in winter and the following summer. Permanent quadrats were also established at a number of the surveyed sites and resurveyed every 3 months.
Of the 267 plant taxa identified, 145 were exotic (non-native). More exotic taxa and fewer native taxa were associated with increasing level of seasonal flow inversion (regulation). In particular, greater numbers of short-lived exotic terrestrial taxa and fewer native woody taxa were associated with increasing level of regulation. Some exotic woody species (e.g. willows) were more common in the unregulated rivers and may have life-history traits favoured by the natural seasonal flow patterns of study area. Multivariate analyses showed that level of regulation had a significant effect on the overall composition of the riverine vegetation.
Our results provide support for the hypotheses that flow regulation adversely affects native species diversity and increases the vulnerability of riparian zones to invasion by exotic species; however, these effects are dependent on plant species' life-history strategies. Our study highlights the importance of natural seasonal flow patterns for sustaining native riverine plant communities. Flow management aimed at maintaining or restoring ecological values should consider seasonal flow patterns. Winter/spring flow peaks may be particularly important for the recruitment of native riverine plants, especially trees and shrubs, and reducing the extent of exotic annuals and grasses. Copyright
This book is primarily written for ecologists needing to analyse data resulting from field observations and experiments. It will be particularly useful for students and researchers dealing with complex ecological problems, such as the variation of biotic communities with environmental conditions or the response of biotic communities to experimental manipulation. Following a simple introduction to ordination methods, the text focuses on constrained ordination methods (RDA, CCA) and the use of permutation tests on statistical hypotheses of multivariate data. An overview of classification methods, or modern regression methods (GLM, GAM, loess), is provided and guidance on the correct interpretation of ordination diagrams is given. Seven case studies of varying difficulty help to illustrate the suggested analytical methods, using the Canoco for Windows software. The case studies utilise both the descriptive and manipulative approaches, and they are supported by data sets and project files available from the book website.
Riparian buffers provide improved protection for water quality and biota, and narrow, fixed-width buffers of native vegetation along streams have been used to mitigate the effects of forest harvest at least since the 1960s. The practice of leaving unmanaged strips of vegetation along water courses in agricultural lands had been used before the 1960s in southern Europe and in eastern North America, but the scientific basis for leaving riparian buffers on forested lands came from observations in the coastal temperate rainforests of western North America. Those observations often were applied to other forested landscapes without further considerations. Fixed-width buffers are administratively simple to implement and assess, and have come to be the norm for streamside protection from forestry. Most guidelines for streamside protection allow some local modification for site and watershed-scale considerations, but frequently, the option to deviate from fixed-width buffers is not exercised because of uncertainty about outcomes. Few experiments have been done to test the efficacy of buffers of a particular width or of site- or landscape-specific modifications.
We examined riparian areas in an old-growth northern hardwood watershed of the Porcupine Mountains, Upper Michigan, focusing on how stream valley geomorphology and associated factors influence the structure and composition of both the overstory and ground-flora vegetation. We collected data from 92 transects stratified among three different geomorphic settings characteristic of portions of the northern Lake States, including a low-gradient, bedrock controlled geomorphic type, a high-gradient bedrock controlled geomorphic type, and a clay lake plain geomorphic type. Individual transects extended from the stream channel to at least 40 m into the adjacent uplands, with transects arrayed roughly perpendicular to streamflow. Along each transect we collected: (1) overstory basal area, species composition, and canopy closure data on a series of 100 m2 plots; (2) ground-flora species composition on a series of 1 m2 plots; and (3) physiographic data (e.g., distance from and elevation above the stream, landform) collected across each transect. Overall, the structure and composition of overstory and ground-flora vegetation is ordered along a complex environmental gradient running from the stream channel into the adjacent uplands. Additionally, our multivariate analyses suggest that the structure and composition of the overstory and ground-flora is related to specific valley floor landforms, as well as distance from and elevation above the bankfull stream channel. Conifer basal area increases across the valley floor landforms (floodplains, terraces, and hillslopes or valley walls) in all three geomorphic settings, while hardwood basal area remains relatively constant across these same landforms. Hardwood basal area, however, dominates the adjacent upland forest ecosystems in all but the clay lake plain geomorphic type which is characterized by fine-textured soils. In all three geomorphic settings, the near stream environment often lacks a significant overstory component, and these fluvial surfaces are often dominated by a mixture of woody shrub and herbaceous species. These results suggest that changes in vegetation are associated with the proximity of the stream, and these patterns are influenced strongly by large-scale landscape factors such as stream valley geomorphology and associated disturbances. Additionally, our results provide much-needed baseline information on the vegetation patterns and dynamics of riparian forests in the northern Lake States, and suggest that riparian areas may require different management strategies than the adjacent upland forest ecosystems.
Mechanical damage by floodwaters is frequently invoked to explain the distribution of riparian plant species, but data have been lacking to relate vegetation to specific estimates of flood damage potential. This research uses detailed estimates of unit stream power (an appropriate measure of the potential for mechanical damage) in conjunction with vegetation cover data to test this relationship at 37 valley‐bottom sites in the Transverse Ranges of Southern California. A computer program, HEC‐2, was used to model the slope and the variation in flow depth and velocity of the 20‐yr flood across the sites. Regression models tested the influence of stream power (and of height above the water table) on the woody species composition of 393 4‐m cross‐section segments of the valley‐bottom sites. Results indicate that unit stream power does have a significant effect on the riparian vegetation, but that the amount of that influence and its importance relative to the influence of height above the water table varies between watersheds. Some species are found primarily in locations of high stream power, while others are limited to portions of the valley bottom that experience only low stream power.
To explore how high flows limit the streamward extent of riparian vegetation we quantified the effects of sediment mobilization and extended inundation on box elder (Acer negundo) saplings along the cobble-bed Gunnison River in Black Canyon of the Gunnison National Monument, Colorado, USA. We counted and aged box elders in 144 plots of 37.2 m2, and combined a hydraulic model with the hydrologic record to determine the maximum shear stress and number of growing-season days inundated for each plot in each year of the record. We quantified the effects of the two mortality factors by calculating the extreme values survived during the lifetime of trees sampled in 1994 and by recounting box elders in the plots following a high flow in 1995. Both mortality factors can be modeled as threshold functions; box elders are killed either by inundation for more than 85 days during the growing season or by shear stress that exceeds the critical value for mobilization of the underlying sediment particles. Construction of upstream reservoirs in the 1960s and 1970s reduced the proportion of the canyon bottom annually cleared of box elders by high flows. Furthermore, because the dams decreased the magnitude of high flows more than their duration, flow regulation has decreased the importance of sediment mobilization relative to extended inundation. We use the threshold functions and cross-section data to develop a response surface predicting the proportion of the canyon bottom cleared at any combination of flow magnitude and duration. This response surface allows vegetation removal to be incorporated into quantitative multi-objective water management decisions. Copyright © 1999 John Wiley & Sons, Ltd.
Floodplain forests have historically been resilient to the effects of flooding because the tree species that inhabit these ecosystems regenerate and grow quickly following disturbances. However, the intensity and selectivity of ungulate herbivory in floodplains has the potential to modify the community-level effects of flooding by delaying forest recruitment and leaving sites vulnerable to invasive species. We established a series of exclosures along an elevation gradient in an actively recruiting floodplain forest along the Upper Mississippi River prior to three large-magnitude flood events. Pre-flood browsing by Odocoileus virginianus (white-tailed deer) ranged from 20% to 85% of all available stems, and reduced subsequent annual tree height growth from 60 cm/yr to approximately 35 cm/yr, regardless of elevation. Tree mortality, in contrast, was positively correlated with both pre-flood browsing rates and the duration of the growing season that the ground elevation of plots was flooded. Mortality rates ranged from approximately 40% in plots that experienced low levels of deer browsing (<30% of stems) and short flood durations (<40 days) to as high as 98% in plots that experienced high levels of deer browsing (>80% of stems) and long flood durations (>50 days). Longer flood durations led to larger shifts in tree community composition, away from heavily browsed and less flood tolerant Acer saccharinum L. (silver maple) and Populus deltoides (cottonwood) and toward species that were more flood tolerant and not preferred by deer. Phalaris arundinacea (reed canarygrass) colonized some portions of all plots, except for those situated at high elevations and protected by exclosures.Hence, herbivory can interact with the local flooding regime of rivers to delay recruitment of some tree species, resulting in shifts in successional trajectories, and leaving young forests vulnerable to invasion by exotic herbaceous species.
Most large rivers have experienced major changes in hydrology and land use over the past century, with concomitant effects on sedimentation, nutrient cycling and biodiversity. To restore and/or enhance these ecosystems, managers need to know where their efforts are most likely to succeed under current hydrologic regimes as well as under potential future hydrologic regimes. We therefore examined changes in forest vegetation and soils across a hydrologic gradient, expressed as flood duration during the growing season, for 320 km of the Upper Mississippi River (UMR) floodplain.