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Terminological distinction between transition and transitional zone, and constituents of sharpness (abruptness): contrast and width.
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Ecological gradients and boundaries are currently in the focus of research interest. A widely accepted terminology, however, is still lacking, thus the use of the terms related to gradients and boundaries continues to be confusing. In this paper, we provide new more elaborated definition of the spatial boundary. We distinguish between the gradient...
Citations
... Ecotones often appear along ecological gradients [12]. Such gradients are created because of spatial shifts in elevation, climate, soil, and many other ecological factors [13]. These regions are sometimes regarded as dynamic zones of community interaction that are inherently unstable over time [14]. ...
... Ecotones have been investigated from an ecological perspective for the past four decades [13,[16][17][18] and have recently received considerable attention in the context of biodiversity protection. Ecotones are "natural laboratories" where researchers may study a range of evolutionary processes, such as speciation and the emergence of new species. ...
The ecotonal zones support populations that are acclimated to changing, fluctuating, and
unstable conditions, and as a result, these populations are better equipped to adjust to expected change. In this context, a hypothesis was tested that there must be vegetation dominated by unique indicator plant species under the influence of ecological gradients in the ecotonal zone of Manoor Valley (northwestern Himalaya), Pakistan. Keeping the aforementioned hypothesis in mind, detailed field studies were conducted during different seasons in 2015-18. Line transect sampling and phytosociological characteristics (density, frequency, cover, and their relative values and Importance Value) were implemented as ecological methods. This investigation documented 97 plant species recorded from seven sampling sites. The community distribution modelling revealed that the ecological variables separate the seven sampling sites into two major plant communities (Indigofera- Parrotiopsis-Bistorta and Ziziphus-Leptopus-Quercus) recognized by TWINSPAN. The IBP communities showed a positive and significant correlation with altitude (1789.6–1896.3 m), sandy soil texture with a slightly acidic pH (6.4–6.5), and higher phosphorous (9–13 mg kg1). In contrast with this, the ZLQ community was recognized on the southern slope under the strong influence of high electrical conductivity (2.82–5.4 dsm1), organic matter (1.08–1.25%), calcium carbonate (5.8–7.6 mg kg1), potassium (202–220 mg kg1), and temperature (28.8–31.8 C). Hence, both communities were found on opposite axes with clear differences based on the ecological gradients. NMDS clustered different
species with similar habitats and different stands with common species, showing that plant species and stands were in a linear combination with ecological gradients. The IPB community has the maximum number of plant species (87 species), Shannon value (H’ = 4), Simpson value (0.98), and Pielou’s evenness value (0.96). Thus, the multivariate approaches revealed unique vegetation with sharp boundaries between communities which might be due to abrupt environmental changes.
... The distribution of benthos along an oceanic depth gradient is influenced by a number of factors including dissolved oxygen concentration, sediment structure, the total organic carbon level in the sediment as well as various disturbance processes and pollution events (e.g. Bakus, 2007;Edros et al., 2011;Ellis et al., 2012 and references therein;Solan et al., 2012;Włodarska-Kowalczuk et al., 2004). Rex et al. (2006), in their global-scale analysis of the meio-, macro-and megafauna, have demonstrated that the abundance of benthic communities decreases with depth, although there are still numerous discrepancies between the global scale models (e.g. ...
The West African continental margin belongs to the least known areas in terms of the ecology of benthic ecosystems. At the same time, this region is influenced by various threats associated with human activities, including industrialisation and oil excavation. Here, we analyse the abundance and distribution patterns of macrozoobenthic communities along the coast of Ghana. The material was collected in 2012 on nine transects at depths ranging from 25 to 1000 m. Over 200 quantitative samples were collected using a 0.1-m2 van Veen grab. Generally, the mean density of macrozoobenthos decreased gradually from the shallow zone (25 m: 231.4 ± 262.2 ind./0.1 m2) down to bathyal depths (1000 m: 55.4 ± 51.4 ind./0.1 m2), but we observed intermediate scale variability in distribution patterns among the transects along the Ghanaian coast. Analysis of environmental factors showed no evidence of substantial pollution, although levels of hydrocarbons, barium and some other toxic metals show some local increases at particular stations, especially on the continental slope. Cluster analysis based on Bray–Curtis similarity and abundance of higher taxonomic groups of macrofauna yielded five groups of stations, while SIMPER analysis demonstrated that polychaetes and amphipods contributed most significantly to within-group similarity. Canonical Correspondence Analysis demonstrated that PAH, THC and toxic metal levels (Ba, Cd, Pb), as well as oxygen concentration, were the most important factors structuring benthic communities.
... Ecotones are border zones between contrasting neighboring habitats that interact with each other and exchange energy and matter at varying rates ( Strayer et al., 2003;Erdős et al., 2011). Some of these habitats can be highly dependent on the supply of nutrients and organic matter from neighboring systems ( Riddle et al., 1990;Mumby et al., 2004). ...
Hard bottoms can negatively affect the surrounding infauna by hosting predatory fauna and modifying local hydrodynamics and sedimentation rates. Considering that these effects depend on the distance to the hard bottoms, we expected that the infaunal structure and recolonization would change accordingly. We assessed whether the distance from a rocky shore alters infaunal recolonization in a subtropical tidal flat. Sediment was defaunated on sites near and far from a rocky shore and the subsequent faunal recolonization was followed for 40 days. The sites near and far from the rocky shore displayed different assemblage structures, which we attributed to local variation in hydrodynamic conditions. Both the total infaunal abundance and the abundance of the dominant species recovered faster at the near site. We indicate that changes in infaunal recolonization at varying distances from natural rocky shores are primarily driven by the availability of adults. Infaunal recovery took less than 2 weeks, but recolonization rates increased near the rocky shore, as a function of its naturally variable assemblage structure and relatively lower species richness and abundances. We suggest that models of infaunal distribution and recolonization should incorporate landscape features such as the presence and distance from rocky bottoms.
... The scale is always a challenge, as a patch can be a leaf, a group of plants, an ecosystem, a landscape or a continent (Wu and David, 14 2002;Wu and Loucks, 1995;Yarrow and Salthe, 2008). Scale is apparently also a problem in transition zones: whereas both Gosz (1993) and Peters et al. (2006) suggest plants, populations, patches, landscapes and biome levels with transition zones, Erdős et al. (2011) exclude elements such as hedgerows, fences and roads from being 'landscape elements'. Despite in-depth discussion, the tenor in the literature is a multiple scales approach (Kark and van Rensburg, 2006). ...
... In addition, a number of terms in articles on transition zones were used synonymously or were applied without an explicit definition (Erdős et al., 2011). For this reason, we (and others : Hufkens et al., 2009) feel that there is a need to propose a set of terms and definitions related to fragmented landscapes so as to establish a well-founded basis for further research on these increasingly important transition zones (Table 2.2). ...
... These definitions and terms represent a basic toolbox for the quantitative description of transition zones in fragmented landscapes. The intention is to establish a relatively straightforward general system of concepts that quantitative ecologists can use; as a result, it will be broadly applicable as well as unambiguous (according to Erdős et al., 2011). The following section depicts a sample area Transition zones include other concepts, such as 'ecotone', 'ecocline', 'interface', 'edge', 'system of gradients', 'ecological boundary' and 'border' (Cadenasso et al., 2003a;Müller, 1998;Yarrow and Marín, 2007). ...
For millennia, humans have affected landscapes all over the world. Due to horizontal expansion, agriculture plays a major role in the process of fragmentation. This process is caused by a substitution of natural habitats by agricultural land leading to agricultural landscapes. These landscapes are characterized by an alternation of agriculture and other land use like forests. In addition, there are landscape elements of natural origin like small water bodies. Areas of different land use are beside each other like patches, or fragments. They are physically distinguishable which makes them look like a patchwork from an aerial perspective. These fragments are each an own ecosystem with conditions and properties that differ from their adjacent fragments. As open systems, they are in exchange of information, matter and energy across their boundaries. These boundary areas are called transition zones. Here, the habitat properties and environmental conditions are altered compared to the interior of the fragments. This changes the abundance and the composition of species in the transition zones, which in turn has a feedback effect on the environmental conditions. The literature mainly offers information and insights on species abundance and composition in forested transition zones. Abiotic effects, the gradual changes in energy and matter, received less attention. In addition, little is known about non-forested transition zones. For example, the effects on agricultural yield in transition zones of an altered microclimate, matter dynamics or different light regimes are hardly researched or understood. The processes in transition zones are closely connected with altered provisioning and regulating ecosystem services. To disentangle the mechanisms and to upscale the effects, models can be used. My thesis provides insights into these topics: literature was reviewed and a conceptual framework for the quantitative description of gradients of matter and energy in transition zones was introduced. The results of measurements of environmental gradients like microclimate, aboveground biomass and soil carbon and nitrogen content are presented that span from within the forest into arable land. Both the measurements and the literature review could not validate a transition zone of 100 m for abiotic effects. Although this value is often reported and used in the literature, it is likely to be smaller. Further, the measurements suggest that on the one hand trees in transition zones are smaller compared to those in the interior of the fragments, while on the other hand less biomass was measured in the arable lands’ transition zone. These results support the hypothesis that less carbon is stored in the aboveground biomass in transition zones. The soil at the edge (zero line) between adjacent forest and arable land contains more nitrogen and carbon content compared to the interior of the fragments. One-year measurements in the transition zone also provided evidence that microclimate is different compared to the fragments’ interior. To predict the possible yield decreases that transition zones might cause, a modelling approach was developed. Using a small virtual landscape, I modelled the effect of a forest fragment shading the adjacent arable land and the effects of this on yield using the MONICA crop growth model. In the transition zone yield was less compared to the interior due to shading. The results of the simulations were upscaled to the landscape level and exemplarily calculated for the arable land of a whole region in Brandenburg, Germany. The major findings of my thesis are: (1) Transition zones are likely to be much smaller than assumed in the scientific literature; (2) transition zones aren’t solely a phenomenon of forested ecosystems, but significantly extend into arable land as well; (3) empirical and modelling results show that transition zones encompass biotic and abiotic changes that are likely to be important to a variety of agricultural landscape ecosystem services.
... Ecotones are border zones between contrasting neighboring habitats that interact with each other and exchange energy and matter at varying rates Erdős et al., 2011). Some of these habitats can be highly dependent on the supply of nutrients and organic matter from neighboring systems (Riddle et al., 1990;Mumby et al., 2004). ...
... Nevertheless, many authors agree that the term environmental ecotone defines a 533 gradient between two adjacent habitats characterized by rather abrupt changes and that it 534 comprises habitats that should be very specific for certain species (Attrill and Rundle, 2002;535 Erdôs et al., 2011;van der Maarel, 1990;Whittaker, 1967). In contrast, an environmental 536 ecocline stands for more gradual changes that may result from mixing of the two communities 537 from the neighboring habitats (Attrill and Rundle, 2002;Erdôs et al., 2011;van der Maarel, 538 1990;Whittaker, 1967). In the present study, the transition zone corresponded to a gradient 539 zone at a cm scale which we characterized by a gradual change of environmental variables 540 such as porosity or EPS ratios and a gradual change of microbial communities (e.g., algal 541 biomass, enzymatic activities and prokaryotic abundance). ...
... In the present study, the transition zone corresponded to a gradient 539 zone at a cm scale which we characterized by a gradual change of environmental variables 540 such as porosity or EPS ratios and a gradual change of microbial communities (e.g., algal 541 biomass, enzymatic activities and prokaryotic abundance). Hence, following these definitions 542 and our findings, we should rather consider the identified transition zone as an environmental 543 ecoclinal boundary (Erdôs et al., 2011). 544 ...
... cita anterior, si bien expone una situación propia de la disciplina científica que estudia la distribución geográfica de la flora y la fauna, recoge una problemática extensiva a muchas de las aproximaciones que, de una u otra manera, buscan establecer límites, bordes o zonas de transición para estudiar un fenómeno determinado, sea este físico, social o ecológico, por mencionar algunos. En ecología, por ejemplo, a pesar de que un ámbito importante de investigación son los gradientes ecológicos y los bordes entre ecosistemas, aún no hay un marco conceptual unificado que permita aproximarse claramente a la comprensión de los procesos que tienen lugar allí, comprensión que depende en gran medida de la escala de análisis que se use ( Erdôs, Zalatnai, Moschhauser, Bátori y Körmöczi, 2011). Estas zonas de transición son de especial interés debido a la mezcla de elementos entre distintos sistemas, situación que desde el punto de vista teórico y empírico ha sido motivo de estudio y asombro por la diversidad que es posible encontrar. ...
Es ya un lugar común calificar las conversaciones de paz entre el gobierno de Colombia y las Fuerzas Armadas Revolucionarias de Colombia (Farc-EP), iniciadas en La Habana en octubre de 2013, como el mayor avance alcanzado hacia la solución política en la historia del conflicto armado colombiano, así como resaltar hechos clave de este avance: de un lado, la metodología; y, de otro, la voluntad y el compromiso de las partes frente al proceso. Pese a sus limitaciones, los acuerdos hasta ahora alcanzados agregan peso específico a la solidez que se percibe en el desarrollo de estas negociaciones, diferenciándolas de los intentos anteriores.
Sin embargo, las percepciones y los sentimientos frente a estos acuerdos parecen debatirse entre la esperanza y un justificado escepticismo, pues si bien representan una posibilidad de apertura hacia soluciones a problemas de gran importancia para el país, encierran también incertidumbres, desafíos y riesgos que no solo las partes en negociación, sino la sociedad en su conjunto debemos enfrentar, en caso de llegar a la ratificación de estos acuerdos con la celebración de uno, de carácter definitivo, de terminación del conflicto armado.
Por ahora, es indispensable apropiarse y analizar dichos acuerdos, para contribuir en la tarea de generar condiciones sociales y de movilización para enfrentar los retos de su implementación. Una sociedad pasiva o indiferente es quizás el mayor riesgo que enfrenta esta posibilidad de cese de décadas de guerra y la apertura hacia la construcción de la paz con justicia social que las mayorías reclaman, más allá del silenciamiento de las armas. Será el conjunto articulado de esfuerzos de cada sector o expresión de la sociedad el que, desde sus acumulados y perspectivas, pueda abrir los surcos para cultivar esa paz largamente anhelada.
En esa dirección, comprendiendo la responsabilidad que desde la academia nos atañe como coadyuvantes de las transformaciones sociales, mediante la construcción democrática y la socialización del conocimiento desde una perspectiva crítica, el grupo de investigación Conflicto, Región y Sociedades Rurales presenta
en este libro, Dime qué paz quieres y te diré qué campo cosechas. Reflexiones sobre lo rural en los diálogos de La Habana, un trabajo colectivo que se ocupa del análisis crítico de algunos aspectos de las negociaciones de paz y de algunos de los acuerdos a los que las partes han llegado, y que tienen relación directa con los asuntos rurales de los que el grupo se ocupa. Hemos enfatizado, sin agotarlo y sin limitarnos al mismo, en el acuerdo «Hacia un nuevo campo colombiano: reforma rural integral», que aborda el problema agrario y de desarrollo rural del país, el primer punto de la agenda de negociaciones que las partes han denominado Política de desarrollo agrario integral, dado el vínculo directo que a estos asuntos nos une.
... This configuration corresponds, for example, to a network with disconnected components (Fig. 23B). Theoretically, disconnected components may be explained also by adjacency in abstract space, although such sharp boundaries are unlikely in nature (Erdös et al., 2011). Conversely, the gap may be (2) covered. ...
... Such a transition belt is analogous to the concept of ecotone, which is "a stress line connecting points of accumulated or abrupt change" (Livingston, 1903;Clements, 1905, p. 277). In other words, an ecotone indicates a narrow transition zone between two adjacent ecosystems with mixed characteristics of the two adjacent ecosystems (Livingston, 1903;Di Castri et al., 1988;Dutoit et al., 2007;Basset et al., 2012; Erdös et al., 2011). Similarly, a peak in ichnodiversity is reached within the aforementioned belt (Fig. 25C), since it contains a mixture of traces from neighboring zones. ...
The Pramollo Basin (Italy-Austria) is one of the richest body and trace fossil sites of the Alps, and exhibits a well-preserved Permian- Carboniferous fluvio-deltaic to marginalmarine sedimentary succession. Despite the exceptionally abundant and well-preserved ichnological heritage, the trace fossils of the Pramollo Basin are not well studied, particularly those of Permian units. This study focuses on the ichnofauna of the Val Dolce Formation (Permian; partly Asselian to partly Sakmarian), with the goal of documenting its ichnological heritage and reconstructing its paleoenvironment. These research questions are addressed by applying network theory, an emerging field of complexity science that focuses on web-like systems made of interconnected entities. An ichnological system can be seen as a set of interlinked ichnotaxa, the topology of which depends on the organism-environment interactions. In addition, traditional paleontological and sedimentological observations are used to reconstruct the paleoenvironment. The following ichnotaxa are documented from the Val Dolce Formation: Archaeonassa isp., Curvolithus simplex, Cylindrichnus isp., Helminthoidichnites tenuis, Nereites missouriensis, Planolites isp., Phymatoderma isp., Pramollichnus pastae, Psammichnites plummeri, Taenidium isp., and Zoophycos isp. Network analysis indicates that the Val Dolce ichnological system is structured, with ichnotaxa organized in environment-driven ichnoassociations: Cylindrichnus-Planolites (proximal delta front), Phymatoderma-Zoophycos (prodelta with dysoxic porewaters), Cylindrichnus- Helminthoidichnites-Curvolithus-Zoophycos (distal delta front-proximal prodelta), and Helminthoidichnites-Taenidium- Curvolithus- Nereites-Zoophycos (prodelta). Furthermore, the delta front-prodelta gradient is accompanied by increasing bioturbation intensity and diversity, reflecting the decreasing intensity of major environmental stressors (hydrodynamics, freshwater input, turbidity). Centrality measures of network analysis allow the topological position of traces to be discerned within the studied system, detecting the paleoenvironmental resolution of individual ichnotaxa. As intersections of sets can be described by networks, the studied ichnoassociations can be considered as occupying intersecting behavioral niches. In analogy with the concept of a Hutchinsonian niche, an ichnotaxon's niche exists in a multidimensional abstract space defined by environmental parameters, which are expressed as spatial variables in the paleolandscape. Consequently, ichnoassociations are not just association patterns, but represent spatial, environmental, and topological entities. This approach allows the reconstitution of spatial relationships between the geographical ranges of ichnotaxa and ichnoassociations, providing information on the physical arrangement of different subenvironments, that is, the structure of the paleoenvironment.
... Basically, vegetation contains two kinds of components: patches and intervening ecotones. Ecotones are transitional zones where spatial changes occur more rapidly than inside the areas they separate and connect (Cadenasso et al. 2003;Erdős et al. 2011a;Risser 1995;Yarrow and Marín 2007). Ecotones are dynamic entities with the potential to vary temporally (Cadenasso et al. 2003;Strayer et al. 2003;Wiens et al. 1985), though the scope of many studies is not large enough to capture variation in ecotones over time. ...
Aims
Central Hungarian inland dune ranges harbor heterogeneous grassland vegetation with an extensive network of ecotones, arranged perpendicular to topography-driven hydrologic gradients. The area suffers from severe aridification due to climate change and local anthropogenic factors, which have led to a dramatic decline of the water table. As a result, groundwater is no longer reachable for low-lying plant communities; thus, we expect they are bound to undergo profound changes. This study investigates how the plant communities respond to this changing environment over time by monitoring ecotones, since they are frequently the hotspots of ecosystem change. We monitored five ecotones along permanent belt transects for 15 years to characterize their dynamic response, and to identify the internal structural changes of the plant communities the ecotones delimit.
Methods
Ecotones were delineated with the split moving window technique. The dynamics of two ecotone parameters, location and contrast, were analyzed with linear regression models incorporating two independent variables: study year as a measure of time since the loss of groundwater, and precipitation as a possible driver of inter-annual variations. The internal changes of the patches separated by the ecotones were analyzed using plant functional groups.
Important Findings
Precipitation had no detectable effect on the ecotone descriptors, but study year influenced ecotones in an unusual fashion. The position of the ecotones appeared to be very stable in time; their dynamics are stationary, not directional as we predicted. The contrasts had clear tendencies; two ecotones disappeared, one new one was formed and two ecotones showed no trend. The internal changes of the patches over time were dramatic, showing a shift toward more xeric and more open plant assemblages in most stretches of the transects. Thus, the dynamic response of the vegetation was not patch expansion vs. shrinking, but fusion vs. division, which profoundly restructured the vegetation pattern. Analysis of plant functional groups revealed that the trends of the ecotone contrasts could be traced back to internal changes of the patches and not to processes within ecotones. Hence, in situations where stationary ecotone dynamics prevail, ecotone position may be a poor indicator of the effects of strong directional environmental changes. However, in this study we show that ecotone contrast can serve as a sensitive tool for monitoring landscape pattern transformations in these cases. Also, this highlights the long-term nature of ecotone responses, which can have implications in landscape planning and restoration measures.
... Ecological boundaries between different ecological systems are common features in heterogeneous landand seascapes. These boundaries are frequently related to contrasts that are reflected in steep environmental gradients at the interface between different ecosystems (Gosz, 1993;Strayer et al., 2003;Farina, 2010;Erdôs et al., 2011). The extension and amplitude of these gradients can affect species distributions across the boundaries (Attrill & Rundle, 2002;Strayer et al., 2003). ...
... We have identified an edge effect related to the influence of rocky shores in tidal flats at a scale of metres. Faunal assemblages in boundaries between different benthic systems are indeed defined by spatially short-scaled processes (Gosz, 1993;Strayer et al., 2003;Erdôs et al., 2011), including microtopography, heterogeneity, physical and chemical characteristics of the sediment, ecological interactions, local currents and resource availability Cusson & Bourget, 1997;Langlois et al., 2005;Gartner et al., 2013).We suggest that any approach to analyse smallscale spatial patterns of macroinvertebrate distribution across habitats should consider the edge effect in such intertidal systems. ...
Negative responses of infauna close to rocky substrates are well known to subtidal bottoms, but there are few studies addressing similar intertidal habitats. We tested the hypothesis that the proximity to rocky shores negatively affects the density and richness of intertidal infauna of tidal flats by assessing infaunal variation across the increasing distances from rocky shores in two tidal flats (Pasto and Limoeiro) of a subtropical estuary in southern Brazil. Total density decreased significantly with the proximity to rocks only in Pasto due to density variations in the two numerically dominant species, the bivalve Anomalocardia flexuosa and the polychaete Armandia hossfeldi. Richness decreased significantly with the proximity to the rocky shores only in Limoeiro. Multivariate analyses revealed significant differences in species and functional groups composition between assemblages near and far from the rocky shores. Assemblage variability patterns were mostly explained by sediment variables. Our hypothesis was partially refuted because negative effects on the infauna were spatially inconsistent, due to differences in species composition between tidal flats, and to distinct responses of individual taxa. Even with the absence of consistent response patterns, the proximity to the rocky shores emerged as a relevant structuring factor of the surrounding intertidal infauna.
