The Species-Environment Relations (SER) Page

Bruce G. Marcot

[This page is designed for wildlife biologists, ecologists, natural resource planners, and others in the fields of wildlife and natural resource management ... although teachers, students, and anyone else are welcome to explore.  Opinions and information are those of Bruce Marcot, and are not intended to reflect those of other people or organizations.]

Quick start:  Here is a reading list.  
                   See bottom of page for a downloadable SER database.
 
What is meant by Species-Environment Relations?

Species-environment relations, or SER, refers to a new approach to describing the environmental relationships of plants and animals in nature, and depicting them in models and databases.

It expands the traditional "wildlife-habitat relationships" (WHR) approach is several key ways, and consists of the following components:

• Macrohabitats -- Like the WHR approach, macrohabitats are described for each species.  Macrohabitats are traditionally described (and mapped) as the vegetation cover types and their structural or successional stages in which a given species occurs.

• Key environmental correlates (KECs) -- Expanding on the WHR approach, SER models also describe a host of environmental factors that most influence the presence or viability of a given species.  These additional factors can include microhabitats, particular substrates, microclimates, and interactions with other organisms or their handiwork (such as ground burrows or tree cavities) ... as well as many factors not traditionally considered in habitat relationships models, such as disturbance from the presence or habitations of humans.  Thus, I use the broader term "environment" (in "species-environment relations" and "key environmental correlates") and not the narrower term "habitat" (as in "wildlife-habitat relationships").

• Key ecological functions (KEFs) -- Unlike the WHR approach, SER models describe the major ecological roles that organisms play in their ecosystems that influence the type, distribution, and abundance of resources or of other organisms. KEFs influence the productivity, diversity, and sustainability of ecosystems and resources.  KEFs can pertain to trophic levels, interactions with other organisms or physical substrates, and energy flow or nutrient cycling.  Literature and information on modeling KEFs can be found here.  

• Other components of an SER model or database can include depictions of species' rarity, conservation status, state or federal listing status, taxonomic status, confidence in scientific knowledge of the species, research information needs, effects of specific management activities on habitats, and links to other databases.

As well, the SER approach defines "wildlife" not just as terrestrial vertebrates (as in the WHR approach) ... but can include all micro- and macro-organism groups ... including soil microbes, micro- and macrofungi, lichens, bryophytes, vascular plants, invertebrates including molluscs and arthropods, and all vertebrates (fish, amphibians, reptiles, birds, and mammals).  Why?  Ecosystems consist of all organisms, and ecological processes and species' roles do not stop at taxonomic boundaries.  Nor is "wildlife" merely multivariate descriptions.
 

Why expand the traditional WHR approach?  What does SER tell you?

Here's the kicker.  An SER approach provides a means of formally addressing processes and functions of organisms in their environment.  The traditional WHR approach essentially assumes that W = f(H), or wildlife are a strict function of (macro)habitat.  This assumes that if you provide habitat, the wildlife will be afforded. In modern wildlife management, this approach was developed by Leopold, Errington, and others of historical fame.

However, the traditional WHR approach fails to acknowledge that the ecological roles of organisms affect the very environments they inhabitat and the other organisms that share those environments.  As such, WHR assumes there is no such influence.

The SER approach also assumes that KEC = f(KEF) or key environmental correlates can also be a function of species' key ecological functions.  Better still, the SER approach assumes S < = > E, or that organisms (S) and their environments (E) are codetermining.  This has implications, in this era of "ecosystem management" of natural resources, for being able to explicitly depict ecological functions that influence the productivity, diversity, and sustainability of ecosystems.
 

Where can you read about the SER approach?

Here is a reading list. 

Here is an SER database that my team and I constructed for the Interior Columbia Basin Ecosystem Management Project.
   (If the above link is non-functional, you can download the database & documentation right here as a 1.7MB zip file.)

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