Variability of epifaunal assemblages associated with native and invasive macroalgae

2010 ◽  
Vol 61 (6) ◽  
pp. 724 ◽  
Author(s):  
Ignacio Gestoso ◽  
Celia Olabarria ◽  
Jesús S. Troncoso
Keyword(s):  
Spatial Scales ◽  
Marine Macroalgae ◽  
Physical Factors ◽  
Spatial And Temporal Variability ◽  
North West ◽  
Space And Time ◽  
Bifurcaria Bifurcata ◽  
Composition And Structure ◽  
Native Algae ◽  
Epifaunal Assemblages

Marine macroalgae harbour abundant and diverse assemblages of epifauna. Patterns of distribution and abundance of epifauna, which are often variable in space and time, differ markedly among macroalgae species. Non-indigenous seaweeds may alter composition and structure of epifaunal assemblages and therefore harbour different assemblages from those associated with native macroalgae. In this study, we analysed the epifaunal assemblages associated with the native algae Bifurcaria bifurcata and the invasive alga Sargassum muticum on the southern part of the Galician coast (north-west Spain). In particular, we tested the hypothesis that there were differences in the epifaunal assemblages associated with the native and invasive algae. We used a hierarchical spatial sampling design to identify if these differences were consistent over space and time. Results indicated that there were significant differences between epifaunal assemblages associated with both algae. The fact that such differences were, in general, consistent at different spatial scales suggests that biological factors related to the specific habitat might play a more important role than physical factors as determinants of epifaunal distribution. This study also showed that S. muticum seems to supply a new and additional habitat for the native epifauna, contributing to increases in the spatial and temporal variability of epifaunal assemblages.

scholarly journals Substantial hysteresis in emergent temperature sensitivity of global wetland CH4 emissions

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kuang-Yu Chang ◽  
William J. Riley ◽  
Sara H. Knox ◽  
Robert B. Jackson ◽  
Gavin McNicol ◽  
...  
Keyword(s):  
Temperature Sensitivity ◽  
Spatial Scales ◽  
Biogeochemical Model ◽  
Spatial And Temporal Variability ◽  
Biogeochemical Models ◽  
Model Parameterization ◽  
Machine Learning Model ◽  
Meta Analyses ◽  
The Relationship ◽  
Global Carbon

AbstractWetland methane (CH4) emissions ($${F}_{{{CH}}_{4}}$$ F C H 4 ) are important in global carbon budgets and climate change assessments. Currently, $${F}_{{{CH}}_{4}}$$ F C H 4 projections rely on prescribed static temperature sensitivity that varies among biogeochemical models. Meta-analyses have proposed a consistent $${F}_{{{CH}}_{4}}$$ F C H 4 temperature dependence across spatial scales for use in models; however, site-level studies demonstrate that $${F}_{{{CH}}_{4}}$$ F C H 4 are often controlled by factors beyond temperature. Here, we evaluate the relationship between $${F}_{{{CH}}_{4}}$$ F C H 4 and temperature using observations from the FLUXNET-CH4 database. Measurements collected across the globe show substantial seasonal hysteresis between $${F}_{{{CH}}_{4}}$$ F C H 4 and temperature, suggesting larger $${F}_{{{CH}}_{4}}$$ F C H 4 sensitivity to temperature later in the frost-free season (about 77% of site-years). Results derived from a machine-learning model and several regression models highlight the importance of representing the large spatial and temporal variability within site-years and ecosystem types. Mechanistic advancements in biogeochemical model parameterization and detailed measurements in factors modulating CH4 production are thus needed to improve global CH4 budget assessments.

A reinterpretation of Scottish ‘hummocky moraine’ and its significance for the deglaciation of the Scottish Highlands during the Younger Dryas or Loch Lomond Stadial

1993 ◽  
Vol 130 (3) ◽  
pp. 301-318 ◽  
Author(s):  
Matthew R. Bennett ◽  
Geoffrey S. Boulton
Keyword(s):  
Environmental Conditions ◽  
Field Survey ◽  
Spatial Scales ◽  
Younger Dryas ◽  
North West ◽  
Scottish Highlands ◽  
Ice Cap ◽  
The North ◽  
Loch Lomond

AbstractThe aim of this paper is to demonstrate that much of the ‘hummocky moraine’ present within the northern part of the LochLomond Readvance ice cap formerly situated in the North West Scottish Highlands may be interpreted as suites of ice-front moraines deposited during active decay. These landforms can be used to reconstruct ice cap decay, whichleads to important insights into the shrinking form of the ice cap and associated environmental conditions. Evidence has been collected from 10803 airphotographs and from detailed field survey. It is presented at three spatial scales.

scholarly journals Enhancing ecosystem restoration efficiency through spatial and temporal coordination

2015 ◽  
Vol 112 (19) ◽  
pp. 6236-6241 ◽  
Author(s):  
Thomas M. Neeson ◽  
Michael C. Ferris ◽  
Matthew W. Diebel ◽  
Patrick J. Doran ◽  
Jesse R. O’Hanley ◽  
...  
Keyword(s):  
Great Lakes ◽  
Large Scale ◽  
Expert Knowledge ◽  
Spatial Scales ◽  
Small Scale ◽  
Space And Time ◽  
Ecosystem Connectivity ◽  
Breeding Grounds ◽  
Local Expert ◽  
Conservation Projects

In many large ecosystems, conservation projects are selected by a diverse set of actors operating independently at spatial scales ranging from local to international. Although small-scale decision making can leverage local expert knowledge, it also may be an inefficient means of achieving large-scale objectives if piecemeal efforts are poorly coordinated. Here, we assess the value of coordinating efforts in both space and time to maximize the restoration of aquatic ecosystem connectivity. Habitat fragmentation is a leading driver of declining biodiversity and ecosystem services in rivers worldwide, and we simultaneously evaluate optimal barrier removal strategies for 661 tributary rivers of the Laurentian Great Lakes, which are fragmented by at least 6,692 dams and 232,068 road crossings. We find that coordinating barrier removals across the entire basin is nine times more efficient at reconnecting fish to headwater breeding grounds than optimizing independently for each watershed. Similarly, a one-time pulse of restoration investment is up to 10 times more efficient than annual allocations totaling the same amount. Despite widespread emphasis on dams as key barriers in river networks, improving road culvert passability is also essential for efficiently restoring connectivity to the Great Lakes. Our results highlight the dramatic economic and ecological advantages of coordinating efforts in both space and time during restoration of large ecosystems.

scholarly journals Climate and plant community diversity in space and time

2020 ◽  
Vol 117 (9) ◽  
pp. 4464-4470 ◽  
Author(s):  
Susan Harrison ◽  
Marko J. Spasojevic ◽  
Daijiang Li
Keyword(s):  
Plant Community ◽  
Plant Diversity ◽  
Phylogenetic Diversity ◽  
Spatial Scales ◽  
Community Diversity ◽  
Niche Conservatism ◽  
Space And Time ◽  
Drying Trend ◽  
Functional And Phylogenetic Diversity ◽  
Over Time

Climate strongly shapes plant diversity over large spatial scales, with relatively warm and wet (benign, productive) regions supporting greater numbers of species. Unresolved aspects of this relationship include what causes it, whether it permeates to community diversity at smaller spatial scales, whether it is accompanied by patterns in functional and phylogenetic diversity as some hypotheses predict, and whether it is paralleled by climate-driven changes in diversity over time. Here, studies of Californian plants are reviewed and new analyses are conducted to synthesize climate–diversity relationships in space and time. Across spatial scales and organizational levels, plant diversity is maximized in more productive (wetter) climates, and these consistent spatial relationships are mirrored in losses of taxonomic, functional, and phylogenetic diversity over time during a recent climatic drying trend. These results support the tolerance and climatic niche conservatism hypotheses for climate–diversity relationships, and suggest there is some predictability to future changes in diversity in water-limited climates.

scholarly journals Variability of Cloudiness over Mountain Terrain in the Western United States

2017 ◽  
Vol 18 (5) ◽  
pp. 1227-1245 ◽  
Author(s):  
Edwin Sumargo ◽  
Daniel R. Cayan
Keyword(s):  
United States ◽  
Large Scale ◽  
Spatial Scales ◽  
High Elevation ◽  
Empirical Orthogonal Functions ◽  
Western United States ◽  
Spatial And Temporal Variability ◽  
Regional Patterns ◽  
Cloud Albedo

Abstract This study investigates the spatial and temporal variability of cloudiness across mountain zones in the western United States. Daily average cloud albedo is derived from a 19-yr series (1996–2014) of half-hourly Geostationary Operational Environmental Satellite (GOES) images. During springtime when incident radiation is active in driving snowmelt–runoff processes, the magnitude of daily cloud variations can exceed 50% of long-term averages. Even when aggregated over 3-month periods, cloud albedo varies by ±10% of long-term averages in many locations. Rotated empirical orthogonal functions (REOFs) of daily cloud albedo anomalies over high-elevation regions of the western conterminous United States identify distinct regional patterns, wherein the first five REOFs account for ~67% of the total variance. REOF1 is centered over Northern California and Oregon and is pronounced between November and March. REOF2 is centered over the interior northwest and is accentuated between March and July. Each of the REOF/rotated principal components (RPC) modes associates with anomalous large-scale atmospheric circulation patterns and one or more large-scale teleconnection indices (Arctic Oscillation, Niño-3.4, and Pacific–North American), which helps to explain why anomalous cloudiness patterns take on regional spatial scales and contain substantial variability over seasonal time scales.

scholarly journals Specifics of boglands freezing in the north and northwest of the European part of Russia under climate change

2019 ◽  
Vol 59 (2) ◽  
pp. 233-244
Author(s):  
V. I. Batuev ◽  
I. L. Kalyuzhny
Keyword(s):  
Ambient Temperature ◽  
Snow Cover ◽  
Spatial And Temporal Variability ◽  
North West ◽  
The North ◽  
Climatic Period ◽  
European Part Of Russia ◽  
Freezing Depth ◽  
Main Factors ◽  
Cover Thickness

Long-term complex observations covering the period of 1949–2018 made possible to determine the average annual characteristics of the depth of freezing of wetlands in the North and Northwest of the European territory of Russia together with main factors of its formation, and spatial and temporal variability. The main factors that determine the depth of freezing of wetlands are ambient temperature, snow cover thickness, and a degree of watering of the micro landscape (water reserves of the micro landscape). At the initial stage of freezing, the major factor is the ambient temperature, when intensity of the freezing reaches 0.5–0.8 cm/day. As snow falls, the freezing rate becomes smaller, and when the snow cover thickness reaches 25–30 cm the depth amounts to 0.2–0.3 cm/day and smaller. It was found that the spatial variability of the freezing depth decreases from large values of the coefficient of variation (0.3–0.4) at the depth of 20–30 cm to less than 0.1 when the depth exceeds 60 cm. The largest values of the depth are recorded in the North of the Kola Peninsula, where sometimes they reach from 84 to 97 cm with the average values of 48–66. In large hummocky bogs, when the seasonal freezing comes down to 63–65 cm it links with the permafrost layer. On average, swamps of these bogs freeze down to a depth of 68 cm. The average climatic depth of freezing of oligotrophic bogs of the NorthWest is 21–24 cm; in some years, freezing of them reaches 32–40 cm. It has been shown that the relative warming of the climate resulted in decreasing in the depth of freezing of wetlands in the North and North-West of the European territory of Russia. Relative to the previous climatic period, the depth of frost penetration in the northern Ilasskoye bog decreased by 32%, and in north-western Lammin-Suo bog – by 31%.

Strategies for Restoring River Ecosystems: Sources of Variability and Uncertainty in Natural and Managed Systems

2003 ◽  
Keyword(s):  
Spatial Variation ◽  
Spatial Scales ◽  
Spatial And Temporal Variability ◽  
Key Factors ◽  
Policy Makers ◽  
River Ecosystems ◽  
Spatial And Temporal Scales ◽  
Lower Productivity ◽  
Biological Attributes ◽  
Stream Biota

<em>Abstract</em>.—Productivity and biodiversity of stream and river ecosystems vary at multiple spatial and temporal scales. Spatial variation in productivity of salmonid fishes varies over two orders of magnitude worldwide and shows lesser, but still considerable, variation at the regional and watershed level. Spatial variation in production and diversity is related to variation in physical, chemical, and biological attributes of watersheds and channels. Channel constraint, gradient, and size are key factors in determining productivity and diversity. Constrained reaches generally support different species and lower productivity than lower-gradient, unconstrained channels. Variation in the condition of stream reaches is greatly influenced by disturbances. Severe disturbances fundamentally change the functional and structural properties of stream ecosystems and alter the way in which the surrounding watershed interacts with the stream. Periodic occurrence of disturbances and the process of recovery play a key role in maintaining spatial and temporal variability in stream conditions and thereby contribute to the productivity and diversity of stream biota. Land use by humans alters the frequency and characteristics of disturbances. As a result, human-altered disturbance patterns often homogenize channel conditions across a watershed rather than introducing diversity. Watershed restoration plans need to recognize the role variability and disturbance play in maintaining the productivity and diversity of stream biota. Incorporating this understanding into watershed management and restoration will require scientists, managers, and policy makers to view watersheds at much longer temporal and larger spatial scales than is currently done.

A Python-based GIS Simulation of the Spatial and Temporal Variation in Evapotranspiration

2019 ◽  
Vol 35 (5) ◽  
pp. 759-765 ◽  
Author(s):  
Mohammed G. Mohammed ◽  
Kathleen M. Trauth
Keyword(s):  
Overland Flow ◽  
Potential Evapotranspiration ◽  
Spatial And Temporal Variation ◽  
Spatial And Temporal Variability ◽  
Water Losses ◽  
Python Script ◽  
Space And Time ◽  
Land Covers ◽  
A Site ◽  
Linn County

Abstract. An assessment of potential evapotranspiration (ET) and direct evaporation is important for informed land management from agriculture to wetlands restoration. These processes vary in space and time, depending on vegetation, soils, and climate throughout the year. Much data has been collected in order to quantify ET for individual plots of land, but means have not been available to provide an integrated view on a landscape scale. A methodology has been developed and an implementing Python script has been written to assess and display the spatial and temporal variability of ET and direct evaporation using a geographic information system (GIS). The methodology utilizes publicly available inputs for broad applicability, and the calculations can be performed for a site with multiple land covers and soil textures. In addition to a visual representation of ET and direct evaporation in space and time, the Python script produces a text file of water losses that could be used in water balance calculations also incorporating precipitation, overland flow and infiltration. The methodology has been demonstrated on a site within Pershing State Park in Linn County, Missouri, and produces results consistent with those expected from hand calculations. All data and code are available in GitHub (https://github.com/TrauthK/Wetlands). Keywords: Evapotranspiration, Evaporation, GIS simulation, Hydrologic modeling, Hydrologic cycle, Python, Raster data, Wetland restoration.

scholarly journals Comparison of satellite-based evapotranspiration estimates over the Tibetan Plateau

2016 ◽  
Vol 20 (8) ◽  
pp. 3167-3182 ◽  
Author(s):  
Jian Peng ◽  
Alexander Loew ◽  
Xuelong Chen ◽  
Yaoming Ma ◽  
Zhongbo Su
Keyword(s):  
Tibetan Plateau ◽  
Vegetation Index ◽  
Water Cycle ◽  
Global Climate ◽  
Spatial Scales ◽  
Accurate Estimation ◽  
The Tibetan Plateau ◽  
North West ◽  
Comparison Results ◽  
Normalised Difference Vegetation Index

Abstract. The Tibetan Plateau (TP) plays a major role in regional and global climate. The understanding of latent heat (LE) flux can help to better describe the complex mechanisms and interactions between land and atmosphere. Despite its importance, accurate estimation of evapotranspiration (ET) over the TP remains challenging. Satellite observations allow for ET estimation at high temporal and spatial scales. The purpose of this paper is to provide a detailed cross-comparison of existing ET products over the TP. Six available ET products based on different approaches are included for comparison. Results show that all products capture the seasonal variability well with minimum ET in the winter and maximum ET in the summer. Regarding the spatial pattern, the High resOlution Land Atmosphere surface Parameters from Space (HOLAPS) ET demonstrator dataset is very similar to the LandFlux-EVAL dataset (a benchmark ET product from the Global Energy and Water Cycle Experiment), with decreasing ET from the south-east to north-west over the TP. Further comparison against the LandFlux-EVAL over different sub-regions that are decided by different intervals of normalised difference vegetation index (NDVI), precipitation, and elevation reveals that HOLAPS agrees best with LandFlux-EVAL having the highest correlation coefficient (R) and the lowest root mean square difference (RMSD). These results indicate the potential for the application of the HOLAPS demonstrator dataset in understanding the land–atmosphere–biosphere interactions over the TP. In order to provide more accurate ET over the TP, model calibration, high accuracy forcing dataset, appropriate in situ measurements as well as other hydrological data such as runoff measurements are still needed.

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