Acts in what Hutchinson (1965) has called the 'ecological theatre' are played out on various scales of space and time. To understand the drama, we must view it on the appropriate scale. Plant ecologists long ago recognized the importance of sampling scale in their descriptions of the dispersion or distribution of species (e.g. Greig-Smith, 1952). However, many ecologists have behaved as if patterns and the processes that produce them are insensitive to differences in scale and have designed their studies with little explicit attention to scale. Kareiva & Andersen (1988) surveyed nearly 100 field experiments in community ecology and found that half were conducted on plots no larger than 1 m in diameter, despite considerable differences in the sizes and types of organisms studied. Investigators addressing the same questions have often conducted their studies on quite different scales. Not surprisingly, their findings have not always matched, and arguments have ensued. The disagreements among conservation biologists over the optimal design of nature reserves (see Simberloff, 1988) are at least partly due to a failure to appreciate scaling differences among organisms. Controversies about the role of competition in structuring animal communities (Schoener, 1982; Wiens, 1983, 1989) or about the degree of coevolution in communities (Connell, 1980; Roughgarden, 1983) may reflect the

https://www.jstor.org/stable/info/2389612

Spatial Scaling in Ecology

Consideration of spatial dynamics in many areas of ecology has received increased attention during the past decade. For example, the role of disturbance in creating and maintaining a spatial mosaic in the rocky intertidal zone was studied. Patch size could be predicted very well by using a model based on past patterns of disturbance and on measured patterns of mussel movement and recruitment. The dynamics of many natural disturbances and their effects on the spatial mosaic have received considerable study in a variety of terrestrial and aquatic systems. This paper demonstrates that a long history of ecological studies provides a basis for the study of spatial patterns and landscape-level processes. However, the emphasis previously was on describing the processes that created the patterns observed in the biota. The explicit effects of spatial patterns on ecological processes have not been well studied; the emphasis on pattern and process is what differentiates landscape ecology from other ecological disciplines. Therefore, this review focuses on the characterization of landscape patterns and their effects on ecological processes.

http://www.faculty.biol.ttu.edu/nmcintyre/Landscape%20Ecology/Turner_1989.pdf

Landscape Ecology: The Effect of Pattern on Process

A tool changer is disclosed for automatically removing a working tool after having been used from the spindle of a machine tool such as a vertical milling machine, transferring the used working tool to a rack which stores a plurality of working tools, picking up from the rack another working tool for the next machining operation, transferring such new working tool to the spindle, and operatively mounting such new working tool on the spindle.

Temperature and Organism Size—A Biological Law for Ectotherms?

Landscape ecology deals with the effects of the spatial configuration of mosaics on a wide variety of ecological phenomena. Because problems in many areas of conservation biology and resource management are related to landscape use, development of a rigorous theoretical and empirical foundation for landscape ecology is essential. We present an approach to research that focuses on how individual-level mechanisms operating in a heterogeneous mosaic produce ecological patterns that are spatially dependent. The theoretical framework that we develop considers the density and distribution of a population among patches as a function of (a) within-patch movement patterns of individuals; (b) emigration from patches as a function of population density, patch configuration, patch context, and within-patch movement; and (c) loss of individuals as they disperse through landscape elements

Ecological mechanisms and landscape ecology

http://www.dartmouth.edu/~mpayres/pubs/gepidem.PDF

Assessing the consequences of global change for forest disturbance from herbivores and pathogens.

The Southern pine beetle, Dendroctonus frontalis Zimmerman (Coleoptera: Scolytidae), is the most destructive insect pest of pine forests in the southeastern United States and in parts of Mexico and Central America (Fig. 1). This is a well-worn statement but is nonetheless richly deserved and quite accurate. The beetle epitomizes the definition of its genus, killer of trees. As such, D. frontalis can overcome even vigorous trees when its populations are large. In the United States, the southern pine beetle primarily colonizes loblolly (Pinus taeda) and shortleaf (P. enchinata) pines, both of which are important sources of pulp and timber. These pines are fast-growing species, inhabiting some of the finest timber-growing land on the continent. In addition, most watersheds in the southern pine forest are dominated by these species, and in many recreational areas high-valued old growth pine prevail.

The Southern Pine Beetle

An hypothesis that there is a fundamental relationship between the epidemiology of Dendroctonus frontalis Zimn. and the occurrence of lightning in pine forests of the southern U.S. is presented. Evidence to support the hypothesis is provided through an examination of 1. historical information on the association of bark beetles and lightning struck pines, 2. the effects of lightning on trees, and 3. the association of thunderstorm frequency and distribution and the incidence of cloud to ground lightning strikes. The hypothesis is interpreted by examination of 1. foraging strategy of D. frontalis and defense strategies of host pines, 2. climatic release of populations, and 3. disturbance theory in ecology.



Zusammenfassung

Die Rolle von Blitzschlag in der Epidemiologie des Kiefernborkenkafers Dendroctonus frontalis



Es wird die Hypothese aufgestellt, das zwischen der Epidemiologie des Kiefernborkenkafers Dendroctonus frontalis und dem Vorkommen von Blitzschlag in den Kiefernwaldern der sudlichen Vereinigten Staaten (USA) ein grundlegender Zusammenhang besteht. Befunde zur Stutze der Hypothese lieferten 1. fruhere Belege uber die Vergesellschaftung von Borkenkafern und vom Blitz getroffenen Kiefern, 2. die Auswirkungen von Blitzschlag auf Baume, und 3. die Beziehung zwischen Vorkommen und Haufigkeit von Gewittern mit der Verbreitung von Blitzeinschlagen. Folgerungen aus dieser Hypothese werden diskutiert im Hinblick auf 1. Wirtswahl- und Befallsstrategie von D. frontalis und Abwehrmechanismen der Wirtsbaume, 2. witterungsbedingte Auslosefaktoren fur Massenvermehrungen, und 3. Storungen und okologisches Gleichgewicht.

The role of lightning in the epidemiology of the Southern Pine Beetle1

Landscapes are the resultant of ecological processes and events operating on many different space-time scales. Large scale disturbance is recognized as a major influence on landscape patterns, but the impact of small scale events is often overlooked. We develop an hierarchical framework to relate lightning and bark beetle population dynamics to the southern pine forest landscape using the concepts of disturbance propagation and amplification. The low level lightning disturbance can be propagated to the landscape level when weather and forest stand structure facilitate bark beetle epidemics. We identify epidemics as biotically-driven episodes that alter landscape structure. The concept of the landscape as the spatial dimension of these episodes is represented in a conceptual model linking insect-host and landscape mosaic interactions.

http://landscape.forest.wisc.edu/LandscapeEcology/Articles/v01i03p129.pdf

Disturbance propagation by bark beetles as an episodic landscape phenomenon

The southern pine bark beetle guild [ Dendroctonus frontalis Zimmermann, D. terebrans (Olivier), Ips calligraphus (Germar), I. grandicollis (Eichhoff), and I. avulsus (Eichhoff)] uses disturbed hosts as habitat for establishment of within-tree populations. We examined the process of colonization of disturbed hosts. Using a procedure designed to emulate effects of a lightning strike, pines were severely disturbed. Response was characterized by measuring beetle populations that (1) arrived at the trees and (2) successfully attacked the trees. Establishment of within-tree populations was characterized by measuring length of egg gallery excavated by attacking adults. The time delay between arrival and attack for D. frontalis and I. calligraphus was also calculated. Attack densities of both species became asymptotic as arrival increased. The percentage of arriving beetles that attacked ranged from 9 to 41 for D. frontalis and from 8 to 59 for I. calligraphus . Numbers of beetles that arrived at the tree but did not attack ranged from 2.7 to 50.2 beetles per dm2 for D. frontalis and from 0.2 to 10.0 beetles per dm2 for I. calligraphus . Most D. frontalis and I. calligraphus attacked on the day they arrived. The delay between arrival and attack was longer for I. calligraphus than for D. frontalis . Egg gallery excavated by D. frontalis increased throughout the study. Eventually, the Ips species were excluded from the lower half of the bole. The low attack densities observed in this study illustrate the significance of disturbed trees in providing refuges for enzootic levels of bark beetles. The aggregation behavior of beetle populations colonizing disturbed hosts supported the contention that these trees serve as foci for initiation of infestations. Furthermore, in disturbed pines, small numbers of beetles were capable of overcoming host defense systems.

Colonization of Disturbed Trees by the Southern Pine Bark Beetle Guild (Coleoptera: Scolytidae)

Role of host disturbance in initiation and growth of infestations of the southern pine bark beetle guild [ Dendroctonus frontalis Zimmermann, D. terebrans (Olivier), Ips calligraphus (Germar), I. grandicollis (Eichhoff), and I. avulses (Eichhoff)] was investigated. Host loblolly were disturbed at four intervals throughout the year and response of the bark beetle guild was monitored. Effects of the disturbance were evaluated by assessing tree mortality resulting from colonization by the bark beetle guild. Numerical responses of beetles to treatment and control trees were measured and the structure of the populations was defined in terms of proportions of the different species responding to the disturbance. All disturbed hosts were discovered and colonized by the bark beetle guild. Multiple-tree infestations developed from 10 of 20 treatment centers. Trees disturbed during the winter persisted as foci for beetle colonization for 133–150 days. The disturbance event did not have to coincide with seasonal development of the bark beetle guild for the hosts to be utilized for colonization. Trees in spring, summer, and fall treatments were colonized immediately after the disturbance. All species of the bark beetle guild were involved in the colonization process. However, structure of the populations (species composition and numbers) was different during the four seasonal treatments. Results of the experiment are interpreted in the context of the hypothesis that lightning, acting as a disturbance, is an integral component of the natural history of the bark beetle guild. The study provides experimental evidence to support the major tenets of the hypothesis.

Richard O. Flamm

Papers

The Southern Pine Beetle

The role of lightning in the epidemiology of the Southern Pine Beetle1

Disturbance propagation by bark beetles as an episodic landscape phenomenon

Colonization of Disturbed Trees by the Southern Pine Bark Beetle Guild (Coleoptera: Scolytidae)

Response of the Southern Pine Bark Beetle Guild (Coleoptera: Scolytidae) to Host Disturbance