Environmental Engineering Reference
In-Depth Information
was initially developed in Europe. With theoretical developments in spatial ecology
and technological advances in remote sensing and geospatial information
processing, landscape ecology became an internationally recognized field of
study in the 1980s. The most salient characteristics of landscape ecology are its
emphasis on the pattern-process relationship and its focus on broadscale ecological
and environmental issues. Key research topics in landscape ecology include eco-
logical flows in landscape mosaics, land use and land cover change, scaling,
relating landscape pattern analysis with ecological processes, and landscape con-
servation and sustainability.
Species Competition and Predation
- Competition and predation are key
interactions between species, and are major foci of thought and study in community
ecology. They are believed to be major forces structuring natural communities,
having critical roles in the determination of species diversity and species composi-
tion, and are regarded as important drivers of evolutionary processes. The
relationships between the niches of different species determine how they interact
through competition and predation, which then have key roles in assembly of local
communities, and their reassembly following perturbations. Niches define patterns
of linkages between species, their resources, and their natural enemies. These
patterns include how linkages change over time, and between different spatial
locations, and define mechanisms by which similar species are able to coexist by
their effects on competition and predation relationships. The human element in the
environment has profound effects on these phenomena. Changing the environment
shifts interactions between species, and profoundly modifies the structure of food
webs. In the modern day, there is much community reassembly, potentially involv-
ing major shifts in competition and predation. Humans transport invasive species
that act as predators, prey, and competitors with potentially major effects on the
community reassembly process.
Species Diversity Within and Among Ecosystems
- Species diversity is a function of
species richness, the number of species in a given locality and species evenness, the
degree to which the relative abundances of species are similar. Commonly used
quantification methods include constructing mathematical indices known as diversity
indexes (the Shannon, Simpson, and Margalef indexes being the most widely used) or
comparing observed patterns of species abundance to theoretical models. The scale of
assessment may range fromwithin a single site or habitat (known as
a
diversity) to the
difference between two or more sites (
b
diversity); which can then be combined to
give
g
diversity - the diversity of the landscape. Early research tended to be
concentrated on largely
a
diversity, but there has been a marked increase in studies
investigating
b
and
g
diversity during the last decade. The species richness aspect of
diversity is often considered the iconic measure of biodiversity since it is well defined
and aligns with our intuitive sense of the concept. As the species level is the level at
which living organisms are most widely known, species have become the major
taxonomic rank for describing biodiversity. Along with populations, it is also the
level that most scientists, managers, and policy makers use when referring to
biological diversity and it provides a useful means for both monitoring and priority
