Small-scale patterns of forest plants and environmental heterogeneity

Vegetatio ◽  
1989 ◽  
Vol 84 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Alexandr A. Maslov
Keyword(s):  
Environmental Heterogeneity ◽  
Small Scale ◽  
Forest Plants

Small-scale Environmental Heterogeneity and Spatiotemporal Dynamics of Seedling Establishment in a Semiarid Degraded Ecosystem

Ecosystems ◽  
2003 ◽  
Vol 6 (7) ◽  
pp. 630-643 ◽  
Author(s):  
Fernando T. Maestre ◽  
Jordi Cortina ◽  
Susana Bautista ◽  
Juan Bellot ◽  
Ramon Vallejo
Keyword(s):  
Seedling Establishment ◽  
Environmental Heterogeneity ◽  
Spatiotemporal Dynamics ◽  
Small Scale ◽  
Degraded Ecosystem

Windthrow in a tropical savanna in Kakadu National Park, northern Australia

1995 ◽  
Vol 11 (4) ◽  
pp. 547-558 ◽  
Author(s):  
Richard J. Williams ◽  
Michael Douglas
Keyword(s):  
National Park ◽  
Environmental Heterogeneity ◽  
Tree Height ◽  
Wind Damage ◽  
Small Scale ◽  
Fire Damage ◽  
Tropical Savanna ◽  
Northern Australia ◽  
Convective Storm ◽  
Deciduous Species

ABSTRACTWindthrow was assessed following a convective storm in a stand of tropical savanna in Kakadu National Park, northern Australia. Over an area of 3 ha, 79 out of 810 trees (9.8%) were damaged; 27 of them were either uprooted or snapped off at the trunk. Logistic regression showed that both species and tree height were significant determinants of the probability of wind damage. Branch loss and either uprooting or trunk snapping was highest in the canopy sub-dominant Eucalyptus porrecta. Damage was lowest in the sub-dominant trees Erythrophleum chlorostachys, a species which is relatively resistant to termite damage, and Terminalia ferdinandiana, a deciduous species which is generally shorter than the main canopy dominants. Damage was intermediate in the two most common canopy dominants, Eucalyptus tetrodonta and E. miniata. Wind damage was greatest in trees taller than 9 m and relatively minor in trees below this height. Wind disturbs savanna trees in a manner opposite to that of fire, because wind damage is greatest in taller trees, whereas fire damage is greatest in smaller trees. This, coupled with significant within-patch variability in the extent of wind damage, may act to increase small-scale environmental heterogeneity in savannas.

scholarly journals Environmental disorder can tip the population genetics of range expansions

2018 ◽  
Author(s):  
Matti Gralka ◽  
Oskar Hallatschek
Keyword(s):  
Environmental Heterogeneity ◽  
Evolutionary Dynamics ◽  
Time Lapse ◽  
Small Scale ◽  
Spontaneous Mutations ◽  
Local Motion ◽  
Reproductive Process ◽  
Range Edge ◽  
Expanding Population ◽  
Number Of Individuals

Evolutionary dynamics is fundamentally shaped by stochastic processes: spontaneous mutations enter populations randomly, and the fate of a mutant lineage is determined by the competition between (random) genetic drift and (deterministic) selection. In populations undergoing range expansions, fluctuations in the reproductive process and the local motion of individuals are enhanced within a small subpopulation at the edge of the population. Range expansions are typically studied in homogeneous environments, but we argue here that the fluctuations at the range edge are susceptible to small-scale environmental heterogeneities that may have a strong effect on the evolutionary dynamics of the expanding population. To show this, we tracked the dynamics of the clones of spontaneous mutations with a tunable fitness effect in bacterial colonies grown on randomly disordered surfaces. We find that environmental heterogeneity on scales much larger than an individual, but much smaller than the total population, can dramatically reduce the efficacy of selection. Time lapse microscopy and computer simulations suggest that this effect is a general consequence of a local "pinning" of the expansion front, whereby stretches of the front are slowed down on a length scale that depends on the structure of the environmental heterogeneity. This pinning focuses the range expansion into a small number of individuals with access to expansion paths, increasing the importance of chance and thus limiting the efficacy of selection.

scholarly journals Small-Scale Fungicide Spray Heterogeneity and the Coexistence of Resistant and Sensitive Pathogen Strains

2005 ◽  
Vol 95 (6) ◽  
pp. 632-639 ◽  
Author(s):  
S. Parnell ◽  
C. A. Gilligan ◽  
F. van den Bosch
Keyword(s):  
Environmental Heterogeneity ◽  
Resistance Management ◽  
Equation Model ◽  
Host Tissue ◽  
Small Scale ◽  
Differential Equation Model ◽  
Susceptible Host ◽  
Incomplete Coverage ◽  
Practical Implications ◽  
Pathogen Strains

Empirical evidence indicates that fungicide-resistant and sensitive strains can coexist for prolonged periods. Coexistence has important practical implications, for example, for the posttreatment recovery of sensitivity and consequently the life expectancy of fungicide products. Despite this, the factors influencing coexistence remain relatively unexplored. Ecological studies have shown that environmental heterogeneity can facilitate the coexistence of different species and subspecific groups. Here we use a simple differential equation model and show that fungicide spray heterogeneity per se is not sufficient for coexistence but that the outcome depends crucially on the competitive relationship between resistant and sensitive strains. The model incorporates the competition between resistant and sensitive pathogen strains for a limited supply of susceptible host tissue on a crop which has received an incomplete coverage of fungicide. We use a combination of invasibility analysis and model simulations to explore the conditions under which coexistence can occur. We further show that the maximum density of healthy host tissue isrealized when resistant and sensitive pathogen strains coexist. A set of key influencing parameters are identified and analyzed, and the consequences of the results for disease and resistance management are discussed.

Reasons to strike first

2019 ◽  
Vol 42 ◽  
Author(s):  
William Buckner ◽  
Luke Glowacki
Keyword(s):  
Intergroup Conflict ◽  
Small Scale

Abstract De Dreu and Gross predict that attackers will have more difficulty winning conflicts than defenders. As their analysis is presumed to capture the dynamics of decentralized conflict, we consider how their framework compares with ethnographic evidence from small-scale societies, as well as chimpanzee patterns of intergroup conflict. In these contexts, attackers have significantly more success in conflict than predicted by De Dreu and Gross's model. We discuss the possible reasons for this disparity.

Exploring Coronal Structures with SOHO

2000 ◽  
Vol 179 ◽  
pp. 403-406
Author(s):  
M. Karovska ◽  
B. Wood ◽  
J. Chen ◽  
J. Cook ◽  
R. Howard
Keyword(s):  
Solar Corona ◽  
Image Enhancement ◽  
Coronal Mass Ejections ◽  
Dynamical Evolution ◽  
Small Scale ◽  
Low Contrast ◽  
Contrast Structures ◽  
Scale Structures ◽  
Small Scale Structures ◽  
Coronal Structures

AbstractWe applied advanced image enhancement techniques to explore in detail the characteristics of the small-scale structures and/or the low contrast structures in several Coronal Mass Ejections (CMEs) observed by SOHO. We highlight here the results from our studies of the morphology and dynamical evolution of CME structures in the solar corona using two instruments on board SOHO: LASCO and EIT.

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