Macroalgal recruitment in artificially disturbed areas: interactive effects of temporal and spatial scale

1998 ◽  
Vol 49 (6) ◽  
pp. 541 ◽  
Author(s):  
Louise M. Emmerson ◽  
Gregory J. Collings
Keyword(s):  
Spatial Scale ◽  
Brown Algae ◽  
South Australia ◽  
Interactive Effects ◽  
Spatial And Temporal Scales ◽  
Disturbed Areas ◽  
Natural Substratum ◽  
Survival And Growth ◽  
Residual Values ◽  
Temporal And Spatial

The effect of the surrounding community and spatial extent of disturbance on recruitment was investigated in a mixed stand (dominated by large brown algae of the order Fucales) on a subtidal rocky platform in South Australia. In particular, survival and growth of Cystophora and Sargassum recruits on natural substratum were examined in artificially cleared areas of three sizes (30 × 30 cm, 60 × 60 cm and 100 × 100 cm). Abundance and growth of recruits was monitored for 6 months at both the edge and the centre of the clearances. The influence of clearance size and position within a clearance on the abundance of recruits changes with time. Initially, the size of clearance was most important, with larger clearances supporting denser stands of recruits. However, after 143 days, position within the clearance became important, with greater mortality at the edges than at the centre. The large residual values associated with the analysis were evidence of the variability of the interactions within this community. The results demonstrate the importance of the consideration of spatial and temporal scales, and particularly the position within a disturbed area, in recruitment studies.

scholarly journals 8-Day and Daily Maximum and Minimum Air Temperature Estimation via Machine Learning Method on a Climate Zone to Global Scale

2021 ◽  
Vol 13 (12) ◽  
pp. 2355
Author(s):  
Linglin Zeng ◽  
Yuchao Hu ◽  
Rui Wang ◽  
Xiang Zhang ◽  
Guozhang Peng ◽  
...  
Keyword(s):  
Spatial Scale ◽  
Air Temperature ◽  
Spatial Scales ◽  
Model Performance ◽  
Global Scale ◽  
Scale Model ◽  
Validation Dataset ◽  
Daily Maximum ◽  
Climate Zone ◽  
Temporal And Spatial

Air temperature (Ta) is a required input in a wide range of applications, e.g., agriculture. Land Surface Temperature (LST) products from Moderate Resolution Imaging Spectroradiometer (MODIS) are widely used to estimate Ta. Previous studies of these products in Ta estimation, however, were generally applied in small areas and with a small number of meteorological stations. This study designed both temporal and spatial experiments to estimate 8-day and daily maximum and minimum Ta (Tmax and Tmin) on three spatial scales: climate zone, continental and global scales from 2009 to 2018, using the Random Forest (RF) method based on MODIS LST products and other auxiliary data. Factors contributing to the relation between LST and Ta were determined based on physical models and equations. Temporal and spatial experiments were defined by the rules of dividing the training and validation datasets for the RF method, in which the stations selected in the training dataset were all included or not in the validation dataset. The RF model was first trained and validated on each spatial scale, respectively. On a global scale, model accuracy with a determination coefficient (R2) > 0.96 and root mean square error (RMSE) < 1.96 °C and R2 > 0.95 and RMSE < 2.55 °C was achieved for 8-day and daily Ta estimations, respectively, in both temporal and spatial experiments. Then the model was trained and cross-validated on each spatial scale. The results showed that the data size and station distribution of the study area were the main factors influencing the model performance at different spatial scales. Finally, the spatial patterns of the model performance and variable importance were analyzed. Both daytime and nighttime LST had a significant contribution in the 8-day Tmax estimation on all the three spatial scales; while their contribution in daily Tmax estimation varied over different continents or climate zones. This study was expected to improve our understanding of Ta estimation in terms of accuracy variations and influencing variables on different spatial and temporal scales. The future work mainly includes identifying underlying mechanisms of estimation errors and the uncertainty sources of Ta estimation from a local to a global scale.

Interactive effects of family and stocking density on survival and growth of the sea urchin Strongylocentrotus intermedius

2019 ◽  
Vol 50 (5) ◽  
pp. 969-982
Author(s):  
Weijie Zhang ◽  
Xiaohui Chen ◽  
Huijie Jiang ◽  
Zhong Wang ◽  
Baofeng Wang ◽  
...  
Keyword(s):  
Sea Urchin ◽  
Stocking Density ◽  
Interactive Effects ◽  
Strongylocentrotus Intermedius ◽  
Survival And Growth

scholarly journals Characteristics of Climate Change and Extreme Weather from 1951 to 2011 in China

2018 ◽  
Vol 15 (11) ◽  
pp. 2540 ◽  
Author(s):  
Chunli Zhao ◽  
Jianguo Chen ◽  
Peng Du ◽  
Hongyong Yuan
Keyword(s):  
Climate Change ◽  
Spatial Scale ◽  
Spatial Scales ◽  
Seasonal Fluctuation ◽  
Extreme Weather ◽  
Temperature And Precipitation ◽  
Weather Variation ◽  
Variation Characteristics ◽  
Established Fact ◽  
Temporal And Spatial

It has been demonstrated that climate change is an established fact. A good comprehension of climate and extreme weather variation characteristics on a temporal and a spatial scale is important for adaptation and response. In this work, the characteristics of temperature, precipitation, and extreme weather distribution and variation is summarized for a period of 60 years and the seasonal fluctuation of temperature and precipitation is also analyzed. The results illustrate the reduction in daily and annual temperature divergence on both temporal and spatial scales. However, the gaps remain relatively significant. Furthermore, the disparity in daily and annual precipitation are found to be increasing on both temporal and spatial scales. The findings indicate that climate change, to a certain extent, narrowed the temperature gap while widening the precipitation gap on temporal and spatial scales in China.

Temporal and spatial distribution and abundance of blue swimmer crab (Portunus pelagicus) larvae in a temperate gulf

2004 ◽  
Vol 55 (8) ◽  
pp. 809 ◽  
Author(s):  
Simon R. Bryars ◽  
Jon. N. Havenhand
Keyword(s):  
Spatial Distribution ◽  
Surface Waters ◽  
Vertical Migration ◽  
South Australia ◽  
Temporal And Spatial Distribution ◽  
Portunus Pelagicus ◽  
Limited Sampling ◽  
Sampling Programme ◽  
Temporal And Spatial ◽  
Stage 1

A plankton-sampling programme for blue swimmer crab (Portunus pelagicus) larvae was conducted in the temperate waters of Gulf St Vincent, South Australia, to investigate: (1) if larval hatching is seasonal; (2) if larvae are restricted to surface waters; (3) if larvae are hatched offshore; and (4) if larval development occurs offshore. The temporal and spatial distribution and abundance of larvae indicated that hatching and zoeal development occur mainly in deeper offshore waters during the warmer months of November to March, and that zoeal development occurs in a range of depths from the neuston to at least 14 m. Although peaks in abundance usually occurred in the upper 3 m, zoeae were distributed throughout the water column, with the majority occurring in sub-surface waters below 1 m depth. There was no evidence for a daylight ontogenetic or tidal vertical migration in the four zoeal stages. Limited sampling revealed no evidence for a diurnal vertical migration in stage-1 zoea. Although the seasonal and inshore-offshore patterns of hatching observed in the study were typical for a portunid species, the broad vertical distribution differed from that observed for P. pelagicus in previous studies.

scholarly journals Localized fast flow disturbance observed in the plasma sheet and in the ionosphere

2005 ◽  
Vol 23 (2) ◽  
pp. 553-566 ◽  
Author(s):  
R. Nakamura ◽  
O. Amm ◽  
H. Laakso ◽  
N. C. Draper ◽  
M. Lester ◽  
...  
Keyword(s):  
Spatial Scale ◽  
Current Sheet ◽  
Plasma Sheet ◽  
Time Scale ◽  
Ionospheric Disturbance ◽  
Flow Shear ◽  
Current Location ◽  
Field Aligned Current ◽  
Temporal And Spatial ◽  
Fast Flow

Abstract. An isolated plasma sheet flow burst took place at 22:02 UT, 1 September 2002, when the Cluster footpoint was located within the area covered by the Magnetometers-Ionospheric Radars-All-sky Cameras Large Experiment (MIRACLE). The event was associated with a clear but weak ionospheric disturbance and took place during a steady southward IMF interval, about 1h preceding a major substorm onset. Multipoint observations, both in space and from the ground, allow us to discuss the temporal and spatial scale of the disturbance both in the magnetosphere and ionosphere. Based on measurements from four Cluster spacecraft it is inferred that Cluster observed the dusk side part of a localized flow channel in the plasma sheet with a flow shear at the front, suggesting a field-aligned current out from the ionosphere. In the ionosphere the equivalent current pattern and possible field-aligned current location show a pattern similar to the auroral streamers previously obtained during an active period, except for its spatial scale and amplitude. It is inferred that the footpoint of Cluster was located in the region of an upward field-aligned current, consistent with the magnetospheric observations. The entire disturbance in the ionosphere lasted about 10min, consistent with the time scale of the current sheet disturbance in the magnetosphere. The plasma sheet bulk flow, on the other hand, had a time scale of about 2min, corresponding to the time scale of an equatorward excursion of the enhanced electrojet. These observations confirm that localized enhanced convection in the magnetosphere and associated changes in the current sheet structure produce a signature with consistent temporal and spatial scale at the conjugate ionosphere.

scholarly journals Survival and Growth of Douglas-Fir Relating to Weeding, Fertilization, and Seed Source

1996 ◽  
Vol 11 (2) ◽  
pp. 62-69 ◽  
Author(s):  
Brian E. Roth ◽  
Michael Newton
Keyword(s):  
Weed Control ◽  
Nitrogen Fertilization ◽  
Seedling Survival ◽  
Seed Orchard ◽  
Douglas Fir ◽  
Seed Source ◽  
Interactive Effects ◽  
Dominant Factor ◽  
Local Source ◽  
Survival And Growth

Abstract The goal of this study was to quantitatively evaluate the individual and interactive effects of weed control, nitrogen fertilization, and seed source on Douglas-fir (Pseudotsuga menziesii) survival and growth in a range of sites and growing conditions in western Oregon. Weed control was the dominant factor influencing seedling survival and growth and accounted for 49% of the explained variation in seedling volume after 2 yr. Nitrogen fertilization had no effect when used in conjunction with weed control and a negative effect when used without weed control. Seedlings from a seed orchard source were significantly larger in diameter and volume than those from a wild local source after two growing seasons, but second-year heights were similar for the two seedling types. Initial seedling size was positively correlated with growth rate. West. J. Appl. For. 11(2):00-00.

Measuring temporal and spatial scales of compound events in the United Kingdom

2020 ◽  
Author(s):  
Aloïs Tilloy ◽  
Bruce Malamud ◽  
Hugo Winter ◽  
Amelie Joly-Laugel
Keyword(s):  
Natural Hazards ◽  
Clustering Algorithm ◽  
Spatial Scales ◽  
Wind Gust ◽  
Temporal Scales ◽  
Spatial And Temporal Scales ◽  
Extreme Wind ◽  
Compound Events ◽  
Temporal And Spatial ◽  
The Impact

&lt;p&gt;Multi-hazard events have the potential to cause damages to infrastructures and people that may differ greatly from the associated risks posed by singular hazards. Interrelations between natural hazards also operate on different spatial and temporal scales than single natural hazards. Therefore, the measure of spatial and temporal scales of natural hazard interrelations still remain challenging. The objective of this study is to refine and measure temporal and spatial scales of natural hazards and their interrelations by using a spatiotemporal clustering technique. To do so, spatiotemporal information about natural hazards are extracted from the ERA5 climate reanalysis. We focus here on the interrelation between two natural hazards (extreme precipitation and extreme wind gust) during the period 1969-2019 within a region including Great Britain and North-West France. The characteristics of our input data (i.e. important size, high noise level) and the absence of assumption about the shape of our hazard clusters guided the choice of a clustering algorithm toward the DBSCAN clustering algorithm. To create hazard clusters, we retain only extreme values (above the 99% quantile) of precipitation and wind gust. We analyse the characteristics (eg., size, duration, season, intensity) of single and compound events of rain and wind impacting our study area. We then measure the impact of the spatial and temporal scales defined in this study on the nature of the interrelation between extreme rainfall and extreme wind in the UK. We therefore demonstrate how this methodology can be applied to a different set of natural hazards.&lt;/p&gt;

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