Search results for "Spatial ecology"
showing 10 items of 191 documents
Influence of spatial precipitation sampling on hydrological response at catchment scale
2014
Retrieving precipitation data from raingauge network is a classical and common practice in hydrology and climatology. These data represent the key input in hydrological modeling to reproduce, for example, the characteristics of a flood phenomenon. The accuracy of the model results is strongly dependent on the consistency of the monitoring network in terms of spatial scale, i.e. network density and location of raingauges, and time resolution. In this context, several studies have been carried out to analyze how the rainfall sampling influences the estimation of total runoff volume. The aim of this paper is to use a physically based and distributed-parameter hydrologic model to investigate ho…
Determinants of macroinvertebrate diversity in headwater streams: regional and local influences
2003
Summary 1 Multiscale determinants of diversity and the relationship between regional (RSR) and local richness (LSR) have recently attracted increased attention, yet such studies on stream organisms remain scarce. We studied the relationships among RSR, β-diversity, LSR and local environmental variables in 120 headwater streams in Finland. Approximately similar-sized areas of eight drainage systems were defined as regions, and 15 stream riffles (= locality) per region were sampled. 2 RSR showed a strong positive relationship with mean LSR (R2 = 0·686), and there was no sign of curvilinearity within the observed range of RSR. RSR was also positively, although non-significantly, related to β-d…
Standardizing the use of fast-field cycling NMR relaxometry for measuring hydrological connectivity inside the soil
2019
Hydrological connectivity inside the soil (HCS) is applied to study the effects of heterogeneities in complex environmental systems. It refers to both the spatial patterns inside the soil (i.e., structural connectivity [SC]) and the physical–chemical processes at a molecular level (i.e., functional connectivity [FC]). NMR relaxometry has been already applied to assess both SC and FC components of the HCS by defining SC and FC indexes. Here, fast-field cycling NMR relaxometry has been applied on a water suspended soil and a sediment to optimize the conditions to standardize the technique. Proton Larmor frequencies (ωL) from 0.01 to 25 MHz were used on samples suspended in three different rat…
Measuring hydrological connectivity inside soils with different texture by fast field cycling nuclear magnetic resonance relaxometry
2022
Abstract The locution “hydrological connectivity inside the soil” is generally used to disclose how the spatial patterns inside the soil affect the physical–chemical processes at a molecular level to influence water transfer into the soil, the surface runoff and related sediment transport. Fast Field Cycling (FFC) Nuclear Magnetic Resonance (NMR) relaxometry has been used to measure both structural and functional connectivity by two indexes indicated as structural (SCI) and functional (FCI) connectivity index. Here, FFC-NMR relaxometry has been applied to analyze three samples: two non-degraded soils, having different grain-size distribution, and a degraded soil sampled in a badland area. P…
Bed scouring downstream of hydraulic structures under steady flow conditions: Experimental analysis of space and time scales and implications for mat…
2011
Abstract Sediment transport and bed deformation in alluvial rivers are space and time dependent. The knowledge of the space and time scales can be helpful for the definition of predictive procedures of an alluvial reach response to changing boundary conditions. In this work, attention is paid to scouring process occurring downstream of the rigid basement of a hydraulic structure. The analysis is focused on transient bed profiles which are determined, under steady flow conditions, by a decrease of the upstream sediment transport rate. In particular, the paper is aimed at improving understanding of the space and time scales required by the alluvial system to reach the equilibrium conditions. …
Measuring soil erosion by field plots: Understanding the sources of variation
2006
Soil erosion plots of different types and sizes are widely used to investigate the geomorphological processes related to soil erosion. This field method has provided a variety of results, depending on the characteristics of the plots, on their suitability to reflect the ecosystem's characteristics and on the objectives of each particular research. The coupling of real soil loss at patch and slope scale within a landscape and the values obtained by field plots depend, among other things, on how good the methodology performs over a set of ecosystem properties, such as those related with temporal and spatial scale issues, disturbance and representation of natural conditions, and the ability to…
Geospatial modelling and map analysis allowed measuring regression of the upper limit of Posidonia oceanica seagrass meadows under human pressure
2018
Abstract Marine coastal ecosystems are facing structural and functional changes due to the increasing human footprint worldwide, and the assessment of their long-term changes becomes particularly challenging. Measures of change can be done by comparing the observed ecosystem status to a purposely defined reference condition. In this paper, a geospatial modelling approach based on 2D mapping and morphodynamic data was used to predict the natural position of the upper limit (i.e., the landward continuous front) of Posidonia oceanica seagrass meadows settled on soft bottom. This predictive model, formerly developed at the regional spatial scale, was here applied for the first time at the Medit…
Predicting patterns of stress and mortality in intertidal invertebrates: applications of biophysical ecology in a changing world
2010
Abstract Background , Questions and Methods Recent studies have emphasized that local and geographic patterns of species distributions can be set by a variety of factors related to weather and climate, including exposure to lethal environmental conditions, indirect effects on consumers and competitors, and sublethal effects of physiological stress on growth and reproduction. Predicting where, when and with what magnitude these impacts are most (and least) likely to occur is imperative if we are to effectively plan for (i.e. adapt to) the effects of climate change.We developed a series of methods for translating patterns of environmental “signals” into organismal responses in intertidal ecos…
Sources and transfer of organic matter in food webs of a Mediterranean coastal environment: Evidence for spatial variability
2006
Abstract The spatial variability in the food web structure of a Mediterranean semi-enclosed coastal environment (Stagnone di Marsala, Italy) was investigated using stable carbon and nitrogen isotopes. Organic matter sources and consumers were sampled in two locations with different environmental features (e.g. hydrodynamic regime, open-sea influence, vegetal coverage). Overall more 13 C-enriched and 15 N-depleted values were found in the central location than in the southern for organic matter sources and consumers. Pelagic consumers (zooplankton and juveniles of transient fish) showed slight spatial differences and in both locations seemed to depend on phytoplankton as the ultimate energy …
Unmanned aerial vehicle technology to assess the state of threatened biogenic formations: The vermetid reefs of mediterranean intertidal rocky coasts
2021
Abstract Vermetid bioconstructions are biogenic formations, built by sessile gastropod molluscs belonging to the family Vermetidae worldwide distributed, occurring in the intertidal and upper subtidal in the rocky shores. In the Mediterranean basin, they occur in complex and tridimensional structures that enhance the local biodiversity, allowing to qualify the structuring species as ecosystem engineers. Due to their ecological relevance and considerable extension along the coasts, we assessed their structural complexity using unmanned aerial vehicle (UAV) technology, as tool of littoral cartography analysis of these bioconstructions, and plaster hemispheres dissolution as a descriptor index…