The Full Picture

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These biological and non-biological components

collectively constitute the structure of an ecosystem.

Ecosystems can be mapped by spatially delineating the

extents of their structural components. An ecosystem’s

distribution on the landscape changes when one or

more of its structural elements change.

The GEOSS ecosystem classification and mapping

approach is based on this premise that ecosystems can

be geospatially represented by mapping and integrat-

ing their structural components. The ecosystems of

South America were recently mapped in this fashion

and represent a proof-of-concept for the approach.

For South America, continent-wide geospatial datasets

were developed for landforms, elevation class, lithol-

ogy and bioclimate, and these were combined to

produce a map of unique abiotic environments for the

continent at a relatively fine spatial resolution (450m).

These abiotic ecosystem footprints were then

combined with land cover, as a proxy for the vegeta-

tion (biota). Ecosystems were thus modelled as unique

physical environments and their associated land cover.

The ecosystems were subsequently labelled (‘cross-

walked’) with ecosystem names from an existing

classification. Six hundred and fifty-nine ecosystems,

each with multiple polygonal occurrences, were

mapped across the continent. Similar work is nearing

completion for the continental United States, and

mapping ecosystems under the GEOSS commission

has been initiated for China, Africa, Australia, and

Indonesia/Pacific.

The GEOSS global ecosystems mapping model

The GEOSS has a conceptual model for mapping the

planet’s terrestrial ecosystems, with freshwater and

marine conceptual models in development and testing.

The ecosystem mapping is essentially a top-down,

biophysical stratification of the planet into unique phys-

ical environments and their associated biota. Data

processing efforts are considerable, but are likely to be

enabled through a combination of GEOSS mandates and

opportunities for fruitful collaborations between stake-

holders.

Earth observation and global

ecosystem mapping and monitoring

The GEOSS global ecosystem mapping approach is

fundamentally an application of earth observation from

satellite imaging, combined with other physical envi-

ronment characterizations derived from field

observations. Several key input layers representing

ecosystem structure (landform, elevation class, soil

moisture etc.) are partly or wholly derived from digital

elevation models. Similarly, land cover is mapped from

image interpretation, and lithology data are often

imagery-supported as well. Climate regions are mapped

using spatially-interpolated field observations from

weather stations. Earth observation data are thus essen-

tial for both mapping global ecosystems, and monitoring

their condition.

recognition of this problem and the need for finer scale, standardized

ecosystem mapping, GEOSS commissioned a new classification and

map of the planet’s terrestrial, freshwater, and marine ecosystems. The

products from this effort will greatly enhance the ability to manage and

conserve global terrestrial, freshwater and marine ecosystems. This

effort supports, and in some cases underpins, several other GEOSS

tasks from the ecosystems and biodiversity societal benefit areas. The

map of global ecosystems resulting from this work will represent the

first attempt to classify and map global ecosystems in a standardized and

robust fashion at a scale appropriate for most ‘on-the-ground’ manage-

ment applications.

Ecosystem distributions

Ecosystems have been defined in many ways, all essentially as

dynamic assemblages of interacting native plant and/or animal

communities that 1) occur together on the landscape or in the water,

and 2) are tied together by similar ecological processes (e.g. fire,

hydrology), underlying environmental features (e.g. soils, geology)

or environmental gradients (e.g. elevation). Ecosystems have both

biological and non-biological components.

Ecological systems of South America

The ecosystems of South America, derived from a biophysical

stratification of the continent using landforms, elevation class,

bioclimate, lithology and land cover

Source: Sayre, R., J. Bow, C. Josse, L. Sotomayor, and J. Touval, Terrestrial Ecosystems of

South America: Washington, D.C., Association of American Geographers, 2007

(accepted for publication)

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