Geoscience Reference
In-Depth Information
Thus
GIS
provides a means for addressing the multidimensional nature of
the species-environment relationship (Shaw and Atkinson 1990) and the need
to integrate large portions of land (eventually the entire biosphere) into the
analysis (Sanderson et al. 1979; Klopatek et al. 1983; Flather and King 1992;
Maurer 1994) to produce robust conservation oriented models.
This chapter is a review of models and methods used in
GIS
-based species
distribution models; it is based on a literature review carried out on
GEOBASE
2
with the following keywords:
GIS
, remote sensing
(
RS
),
wildlife, habitat,
and
dis-
tribution.
The 82 papers collected were classified according to the main tool
used (
GIS
or
RS
), the modeling approach, the analysis technique, the discussion
of the assumptions, and the presence of a validation section. At the same time,
information was gathered on the use of the term
habitat,
the number of vari-
ables used for modeling, and the kind of output produced.
Far from being comprehensive, the review was the starting point for a ten-
tative classification of
GIS
distribution models that is presented in this chapter;
at the same time, it allowed us to focus attention on some issues that we con-
sider among the most important for correct use of
GIS
in species distribution
modeling. In fact, although it offers powerful tools for spatial analysis,
GIS
has
been largely misused and still lacks a clear framework to enable users to exploit
its potential fully.
These issues range from unspecified objectives in the process of model
building to the lack of adequate support for the assumptions underlying the
models themselves. A large part of the chapter is devoted to the problem of val-
idation, which we believe is crucial throughout the process of model building
but is very seldom taken into account.
Before discussing these issues, we address the problem of terminology
inconsistencies, which has a much broader extent in ecology than the specific
realm of species distribution modeling. The problem emerges from our review
and is probably caused, in this context, by misleading use of the same term in
the different disciplines that have come to coexist under the wide umbrella
of
GIS
.
Terminology
j
Multidisciplinary fields of science are very appealing because they bring
together people with different experience and backgrounds whose constructive
exchange of ideas may generate new solutions. In fact, many solutions that
have been successfully developed and used in one field of science may, with
