Environmental Engineering Reference
In-Depth Information
Remote sensing
The science and art of obtaining information about an object,
area, or phenomenon through the analysis of data acquired by
a device that is not in contact with the object, area, or phenom-
enon under investigation (e.g., via a satellite image).
Definition of the Subject
Ecotones are areas of transition between ecological communities, ecosystems, or
ecological regions (such as Mediterranean and desert). Ecotones often occur
along ecological gradients. Such gradients are created as a result of spatial shifts
in elevation, climate, soil, and many other environmental factors. Ecotones com-
monly coincide with areas of sharp climatic transition along environmental
gradients. They occur at multiple spatial scales, from continental-scale transitions
between major biomes to small-scale ecotones where local vegetation communities
and microhabitats coincide. They show a diversity of boundary types that range
from natural boundaries (e.g., altitudinal, latitudinal transitions) to human-
generated ecotones (e.g., forest clear-cut edges or urban ecotones). Ecotones have
been studied in the past four decades in an ecological context and in recent years are
receiving increasing attention in the context of biodiversity conservation. Various
studies have shown that species richness and abundances tend to peak in ecotonal
areas, though exceptions to these patterns occur. Ecotones are “natural laboratories”
for studying a range of evolutionary processes, such as the process by which new
species form, also termed speciation. Some researchers argue that ecotones deserve
high-conservation investment, potentially serving as speciation and biodiversity
centers. Because ecotones are often small in size and relatively rich in biodiversity,
conservation efforts in these areas may prove to be an efficient and cost-effective
conservation strategy.
Introduction
While substantial research in the past decades has focused on distinct ecological
regions, communities, and ecosystems, areas of transition between these regions
have received much less attention. These areas, nevertheless, sustain rich and
unique biodiversity and may have an important role in sustaining future biodiver-
sity. However, studies have shown that species richness and abundances tend to
peak in ecotonal areas, though exceptions to this pattern occur. This is likely
because ecotonal areas hold species from two or more neighboring communities
and possibly due to high spatial heterogeneity and high speciation rates in ecotonal
areas. In addition, ecotones have been shown, in some cases, to hold ecotonal
species and genotypes that are uniquely characteristic of the ecotone.
