Dealing with landscape ecology issues involves a detailed analysis of the problems occurring not only within small areas, but also on a much bigger scale, which means that the phenomenon of spatial scale must be introduced. Allowing to draw the line between the issues that can be handled on a relatively small scale and the problems that can be classified as global, spatial scale is a measure of length, width and other spatial characteristics of a specific area.
However, the phenomenon of spatial scale embraces not only space as it is, but also the factors that affect a certain area, splitting these factors into micro and macro ones. Though the issue seems quite simple, it is quite hard to define spatial scale.
Despite the numerous attempts that have been undertaken to nail down the essence of spatial scale, there are still certain ambiguities concerning what exactly spatial scale involves: “Spatial scale is interpreted differently, depending on the disciplines and this causes some confusion” (Lee, 2008, 22).
However, according to Lee, there still is a way to provide a definition of spatial scale that will satisfy all the branches of science, including landscape ecology: “Spatial scale represents the geographic extent within which the mutual influences of neighboring observations are made effective” (Lee, 2008, 22). Even though the provided definition might seem somewhat vague, it still encompasses the key characteristic of spatial scale.
It is also important to add that the given definition allows to specify the role of spatial scale in landscape ecology researches as “determining related costs/benefits from the two different land use structures” (Lee, 2008, 22). Taking about spatial scale, one must mention such elements as spatial top-up and bottom-down factors.
There is no secret that all areas are influenced to a great extent by the organisms that inhabit it. While the impact that the latter have on specific areas might be quite unnoticeable at first sight, giving it a second thought, one will be able to see that these organisms change scale, shape and even the characteristics of a certain area.
Starting from huge mammals, largely carnivores, that affect the organic processes taking place in a certain area, to the tiniest algae that slowly but surely drain great basins and create steppes where water used to make most of the area, all these organisms have a direct influence on a specific area and its landscape.
To understand the nature of landscape changes and see the impact of these organisms on the area directly, scholars came up with a classification that allows to draw the line between the most and the least influential factors. The so-called top-up factors are the ones provided by the organisms taking top places in the food chain, i.e., large mammals.
On the contrary, the inhabitants of a specific area, which have little to no impact on the landscape and can influence it only after gathering in large groups are defined as the bottom-down factors. As Turner, Gardner, and O’Neill explain, “Individual-based models represent a bottom-up approach to modeling population dynamics in space” (Turner, Gardner, and O’Neill, 2001, 242).
Therefore, the classification that splits the existing ecological factors into top-up and bottom-down ones is supposed not only to display the relations between the scale of a factor and the scale of its influence on a certain area, but also to show the way in which these factors are related.
To consider the effects that top-down factors have on the landscape ecology, it is reasonable to take a closer look at the way in which a large mammal influences a specific area. As an example, a North American bobcat can be considered.
According to the existing evidence, though the population of bobcats is declining in a rapid pace, the given species still affect the landscape greatly by keeping the population of rodents within a reasonable size (Hanson, 2001). Therefore, the effect that rodents have on the landscape, i.e., the creation of new burrows, etc. is kept to a minimum. Thus, the bobcat population in the United States has a huge effect on the landscape.
Compared to the effect that the top-down factors, such as carnivores, have on the landscape, the influence of the bottom-up factors might seem not that great; however, the latter still have a strong impact on landscape, which can be proven by considering the life cycle of a Northern short-tailed shrew.
Though the size of the given mammal is much less than the one of a bobcat, a shrew still has considerable impact on the landscape for the reasons mentioned above. Like a number of rodents that live underground, shrews dig holes that spread farther and farther until they affect the landscape and lead to the development of hollows.
The changes in the structure of the land affect the plants that grow there. Either spurring their growth or making them die out, these changes thus contribute to their number. Since these plants also serve as food for other herbivores, the population of the latter decreases. Hence, the landscape is changed.
Hanson, J. 2001. There’s a bobcat in my backyard: Living with and enjoying urban wildlife. University of Arizona, Tucson, AZ.
Lee, G. 2008. A spatial statistical approach to examining sprawled urban growth patterns over time in the framework of geographic information systems (GIS). UMI, Ann Arbor, MI.
Turner, M. G., R. H. Gardner, and R. V. O’Neill. 2001. Landscape ecology in theory and practice: Pattern and process. Springer Science and Business Media, New York, NY.