Effects of Forest Fragment Area on Interactions Between Plants and Their Natural Enemies: Consequences for Plant Diversity at Multiple Spatial Scales

Abstract Eutrophication is a widespread environmental change that usually reduces the stabilizing effect of plant diversity on productivity in local communities. Whether this effect is scale dependent remains to be elucidated. Here, we determine the relationship between plant diversity and temporal stability of productivity for 243 plant communities from 42 grasslands across the globe and quantify the effect of chronic fertilization on these relationships. Unfertilized local communities with more plant species exhibit greater asynchronous dynamics among species in response to natural environmental fluctuations, resulting in greater local stability (alpha stability). Moreover, neighborhood communities that have greater spatial variation in plant species composition within sites (higher beta diversity) have greater spatial asynchrony of productivity among communities, resulting in greater stability at the larger scale (gamma stability). Importantly, fertilization consistently weakens the contribution of plant diversity to both of these stabilizing mechanisms, thus diminishing the positive effect of biodiversity on stability at differing spatial scales. Our findings suggest that preserving grassland functional stability requires conservation of plant diversity within and among ecological communities.

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Inhibition of coral settlement at multiple spatial scales by a pervasive algal competitor

Marine Ecology Progress Series ◽

10.3354/meps12879 ◽

2019 ◽

Vol 612 ◽

pp. 29-42 ◽

Cited By ~ 4

Author(s):

NR Evensen ◽

C Doropoulos ◽

KM Morrow ◽

CA Motti ◽

PJ Mumby

Keyword(s):

Spatial Scales ◽

Coral Settlement ◽

Multiple Spatial Scales

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Assessment of clogging in constructed wetlands by saturated hydraulic conductivity measurements

Water Science & Technology ◽

10.2166/wst.2019.045 ◽

2019 ◽

Vol 79 (2) ◽

pp. 314-322 ◽

Cited By ~ 6

Author(s):

F. Licciardello ◽

R. Aiello ◽

V. Alagna ◽

M. Iovino ◽

D. Ventura ◽

...

Keyword(s):

Sensitivity Analysis ◽

Hydraulic Conductivity ◽

Constructed Wetlands ◽

Spatial Scales ◽

Pilot Scale ◽

Laboratory Scale ◽

Test Method ◽

Conductivity Measurements ◽

Multiple Spatial Scales ◽

Ks Values

Abstract This study aims at defining a methodology to evaluate Ks reductions of gravel material constituting constructed wetland (CW) bed matrices. Several schemes and equations for the Lefranc's test were compared by using different gravel sizes and at multiple spatial scales. The falling-head test method was implemented by using two steel permeameters: one impervious (IMP) and one pervious (P) on one side. At laboratory scale, mean K values for a small size gravel (8–15 × 10−2 m) measured by the IMP and the P permeameters were equal to 19,466 m/d and 30,662 m/d, respectively. Mean Ks values for a big size gravel (10–25 × 10−2 m) measured by the IMP and the P permeameters were equal to 12,135 m/d and 20,866 m/d, respectively. Comparison of Ks values obtained by the two permeameters at laboratory scale as well as a sensitivity analysis and a calibration, lead to the modification of the standpipe equation, to evaluate also the temporal variation of the horizontal Ks. In particular, both permeameters allow the evaluation of the Ks decreasing after 4 years-operation and 1–1.5 years' operation of the plants at full scale (filled with the small size gravel) and at pilot scale (filled with the big size gravel), respectively.

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FORMULATION OF THE HEAT CONDUCTION EQUATION FOR HETEROGENEOUS MEDIA WITH MULTIPLE SPATIAL SCALES USING REITERATED HOMOGENIZATION

Revista de Engenharia Térmica ◽

10.5380/reterm.v15i1.62165 ◽

2016 ◽

Vol 15 (1) ◽

pp. 96

Author(s):

E. Iglesias-Rodríguez ◽

M. E. Cruz ◽

J. Bravo-Castillero ◽

R. Guinovart-Díaz ◽

R. Rodríguez-Ramos ◽

...

Keyword(s):

Heat Conduction ◽

Small Parameter ◽

Heat Conduction Equation ◽

Heterogeneous Media ◽

Spatial Scales ◽

Conduction Equation ◽

Small Scale ◽

Multiple Spatial Scales ◽

Effective Coefficients ◽

Reiterated Homogenization

Heterogeneous media with multiple spatial scales are finding increased importance in engineering. An example might be a large scale, otherwise homogeneous medium filled with dispersed small-scale particles that form aggregate structures at an intermediate scale. The objective in this paper is to formulate the strong-form Fourier heat conduction equation for such media using the method of reiterated homogenization. The phases are assumed to have a perfect thermal contact at the interface. The ratio of two successive length scales of the medium is a constant small parameter ε. The method is an up-scaling procedure that writes the temperature field as an asymptotic multiple-scale expansion in powers of the small parameter ε . The technique leads to two pairs of local and homogenized equations, linked by effective coefficients. In this manner the medium behavior at the smallest scales is seen to affect the macroscale behavior, which is the main interest in engineering. To facilitate the physical understanding of the formulation, an analytical solution is obtained for the heat conduction equation in a functionally graded material (FGM). The approach presented here may serve as a basis for future efforts to numerically compute effective properties of heterogeneous media with multiple spatial scales.

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