Search results for "spatial"
showing 10 items of 2121 documents
Assessing the capacity of different urban forms to preserve the connectivity of ecological habitats
2011
International audience; This paper addresses the relationship between anthropogenic forest habitat fragmentation and the form of urban patterns. Using a two-step methodology we first generate 40 theoretical residential development scenarios following a repeatable procedure; the simulated urban forms are either moderately compact or fractal. Then, we compare the scenarios according to the functional connectivity of the remaining forest habitat using a graph-based approach. The methodology is applied to the urban region of Besançon (France), where forest surfaces are considered as a generic habitat for several animal species. Results obtained show that fractal scenarios of residential develop…
Determining stingray movement patterns in a wave-swept coastal zone using a blimp for continuous aerial video surveillance
2020
Stingrays play a key role in the regulation of nearshore ecosystems. However, their movement ecology in high-energy surf areas remains largely unknown due to the notorious difficulties in conducting research in these environments. Using a blimp as an aerial platform for video surveillance, we overcame some of the limitations of other tracking methods, such as the use of tags and drones. This novel technology offered near-continuous coverage to characterise the fine-scale movements of stingrays in a surf area in Kiama, Australia, without any invasive procedures. A total of 98 stingray tracks were recorded, providing 6 h 27 min of movement paths. The tracking data suggest that stingrays may u…
Predicting common bottlenose dolphin habitat preference to dynamically adapt management measures from a Marine Spatial Planning perspective
2016
Abstract At the European Level, SACs (Special Areas of Conservation) are considered among the most reliable tools for increasing the efficiency of protective actions and to identify species vulnerability hotspots across spatial scales. Nevertheless, SACs may fail in their scope when design and management are not dynamically adapted to meet ecological principles. Knowledge of the spatial distribution of relevant key species, such as common bottlenose dolphin (Tursiops truncatus), is crucial in order to achieve the objective of the Habitat Directive (92/43/EEC), and is a fundamental step in the process of Marine Spatial Planning. From this perspective, new data and analysis are required to pr…
Spatial variability of stable carbon and nitrogen isotope ratios in a Mediterranean coastal lagoon
2005
Exploring the trophic pathway of organic matter within the Mauguio lagoon (southern France, western Mediterranean), we found spatial differences in the isotopic composition (both δ13C and δ15N values) of organic matter sources (primary producers, particulate and sedimentary organic matter), which were mirrored in the upper trophic levels (invertebrates and fish). On average, δ13C was heavier by about 1.5–2‰ in the location under marine influence than in the sites influenced by freshwater discharge. The opposite trend was found for δ15N, which attained maximum values in the north-central zone influenced by freshwater delivery. For both C and N stable isotope ratios, the highest spatial varia…
Fruit body based inventories in wood-inhabiting fungi: Should we replicate in space or time?
2016
We assessed the effect of survey design on the results when conducting fruit body surveys of wood-inhabiting fungi. Our results demonstrate that the optimal design depends on the ecological question to be addressed, as well as the group of fungal species under research. If the aim is to record the total species richness in a dead wood unit or to estimate the population size of a species, repeating the survey over time is generally necessary. However, if the aim is to estimate the total species richness in the forest or to assess how environmental covariates influence species richness or community composition, it is generally more efficient to increase the number of dead wood units than to r…
Grazers increase β-diversity of vascular plants and bryophytes in wood-pastures
2016
Questions How does the presence of grazers impact plant diversity at various spatial scales? What are the effects on plant β-diversity and its two components, species turnover and nestedness? Are the effects caused by defoliation, trampling or defecating? Location Twenty-four currently grazed and 24 abandoned wood-pasture sites in Central Finland. Methods The species richness of vascular plants and bryophytes was studied at four spatial scales: within 4-m2 subplots (α1), within 100-m2 plots (α2), within sites (α3) and within the landscape (γ). β-Diversity was studied between subplots within plots (β1), between plots within sites (β2) and between sites within the landscape (β3). Results Curr…
Spatial and temporal variation of community composition and species cover following dune restoration in the Devesa de Albufera (Valencia, Spain).
2015
Plant populations were reintroduced to the coastal dune bar of the Devesa de Albufera from 1988 to 2004; different coastline sections received different species composition and cover. With the aim to detect spatial and temporal variation of floristic diversity, we compared current species composition and cover across the length of the Devesa and across the dune bar with those imposed at the time of restoration. Non-metric multidimensional scaling (NMDS) detected significant differences both across the dune faces and across the coast sections. Differences across the dune faces reflect the sea-inland ecological gradient and resulted from a spatial rearrangement of plant populations: Calystegi…
Spatial pattern of the threatened epiphytic bryophyte Neckera pennata at two scales in a fragmented boreal forest
1999
The spatial pattern and occurrence of a threatened bryophyte, Neckera pennata, were studied in relation to the abundance and pattern of suitable substrate trees at two spatial scales: I) in a 4 x 4 km fraction of fragmented, mostly managed southern boreal forest landscape, and 2) in an old-growth forest stand within this landscape, with abundant occurrence of suitable habitats. To explore in detail the spatial clustering of N. pennata at the forest stand scale, we applied a second order point process analysis based on the Ripley's K-function for binary point patterns. Neckera pennata proved to be a rare species in the studied landscape: it was found only on 31 Populus tremula trees. At the …
Population variability in space and time.
2000
One of the most ubiquitous phenomena of all natural populations is their variability in numbers in space and time. However, there are notable differences among populations in the way the population size fluctuates. One of the major challenges in population and community ecology is to explain and understand this variety and to find possible underlying rules that might be modified from case-to-case. Population variability also has a spatial component because fluctuations are often synchronized over relatively large distances. Recently, this has led to growing interest in how 'internal' (density-dependent) processes interact with 'external' factors such as environmental variability.
The Spatial Dimension in Population Fluctuations
1997
Theoretical research into the dynamics of coupled populations has suggested a rich ensemble of spatial structures that are created and maintained either by external disturbances or self-reinforcing interactions among the populations. Long-term data of the Canadian lynx from eight Canadian provinces display large-scale spatial synchrony in population fluctuations. The synchronous dynamics are not time-invariant, however, as pairs of populations that are initially in step may drift out of phase and back into phase. These observations are in agreement with predictions of a spatially-linked population model and support contemporary population ecology theory.