Environmental Engineering Reference
In-Depth Information
Mountains, NY, and then followed it into soil, microbial biomass, understory plants,
tree roots, wood, and leaves, and found that most of the nitrogen stayed in the soil.
Alternatively, ecosystem scientists often use natural abundance studies of stable isotopes
to follow the movement of materials through ecosystems.
Substances other than isotopes can be used as tracers as well. For instance, certain fatty
acids cannot be synthesized by animals and are made only by particular kinds of algae. By
analyzing the fatty acid content of zooplankton and fish, we can trace the contribution of
different kinds of algae throughout the food web. Caffeine, which is not readily degraded
in conventional sewage treatment plants, is sometimes used as a tracer for sewage. The
kinds of substances that can be used as tracers are highly varied, limited only by the inge-
nuity and analytical capabilities of the investigator.
Spatial Data
Where are the regions of high and low productivity around the globe? How do they
change over the seasons? These are questions that can now be answered largely as a result
of the availability of remote sensing tools and spatially explicit data. The ability to collect,
represent, and analyze spatially explicit data has risen exponentially over the past decade.
Remote sensing and the georeferencing of basic data on landscape characteristics such as
elevation, water bodies, land cover, and geological materials have opened the door to a
description of ecosystem structure over large areas. Geographic information systems
(GISs) allow analysis of the relationships between these structures and fluxes in or out of
these systems. For example, the variation in atmospheric deposition across the mountain-
ous terrain of Acadia National Park or Great Smoky Mountain National Park can be
described by a GIS model that links empirical measurements to landscape features that are
described in the GIS (
Figure 1.6
). Such spatially explicit models greatly enhance our ability
to identify places on the landscape and times that may be subject to particularly high
levels of atmospheric deposition (
Weathers et al. 2006
). GIS and other technologies are
being used creatively and hold tremendous potential for understanding ecosystem pro-
cesses across heterogeneous landscapes. Other newly emerging tools and techniques are
described in Chapter 17.
FROM THERE TO HERE: A SHORT HISTORY
OF THE ECOSYSTEM CONCEPT IN THEORY
AND PRACTICE
Ecosystem science is a relatively young discipline, largely developed since the mid-
twentieth century (
Hagen 1992; Golley 1993
; indeed, the term ecology was coined only in
1866). The concept of an ecosystem was first formally proposed by the English botanist
Arthur
Tansley in 1935
, although related ideas were in circulation for at least a century
before this. For instance, the idea of a biosphere (a region near the Earth's surface in which
living organisms are a dominant geochemical force) was outlined by the French scientist
Jean-Baptiste Lamarck in 1802; the term biosphere was coined in 1875 by an Austrian geolo-
gist, Eduard Suess, in describing the genesis of the Alps; and the concept of a biosphere
was fully elaborated by the Russian mineralogist Vladimir Vernadsky in 1926. Other
