-----Original Message-----
From: Jolley, Leonard - Beltsville, MD
Sent: Thu 1/25/2007 12:36 PM
To: William Adair
Cc:
Subject: RE: Ecological Sites vs. Ecological Systems
Hello Susan and Bill,
The USDA NRCS ecological site description concept is quite distinct and
different from the Natureserve product. Ecological site descriptions are
developed in conjunction with the National soil survey program.
Ecological sites have their roots in the 'range site' concept, and
range sites did owe a great deal to the vision of rangeland ecology articulated
by Dyksterhuis in his 1949 and subsequent papers.
Two papers that better describe the current rationale for ecological
sites are:
Stringham et al. March 2003. State and Transition modeling: An
ecological process approach. J. Range Management 56:106-113
Bestelmeyer et al. March 2003. Development and use of state and
transition models for rangelands. J. Range Management 56: 114-126.
Ecological sites are defined as:
"A distinctive kind of land with specific physical characteristics that
differs
from other kinds of land in its ability to produce a distinctive kind
and amount of vegetation."
Brandon Bestelmeyer with USDA ARS at the Jornada Experimental Range has
pointed out (in a personal communication):
"Ecological Systems (ES) are sort of an ad hoc level in the NVC
hierarchy that was produced for mapping, attempts to map plant associations led
to too much inaccuracy, so the classes mapped were broadened. Ecological Site
Descriptions (ESDs) are climo-edaphic units of land that may support a range of
plant communities embedded within several alternative states that differ in
ecosystem functions (e.g., nutrient cycling, hydrology). The biggest difference
is that ecological system constructs are based on existing vegetation rather
than potential vegetation and ecological systems are very broad.
In our experience in the Chihuahuan Desert, ecological system systems
classes describe gross vegetation structure (such as semidesert grassland or
shrubland) that 1) homogenize/ignore important differences in vegetation
structure from a management perspective (e.g., pristine grasslands and shrub
invaded/at risk states within a âsemidesert grasslandâ ES) and 2) include
both historical shrublands as well as shrublands representing degraded, former
grasslands in the same ES class.
So the crosswalk between ES and ESD classes is that ES classes MAY
represent classes of communities, combinations of communities, alternative
vegetation states, or combinations of alternative states occurring within one
or more ESD classes, depending on how ES classes were defined in an area. In my
opinion, ES classes are great for visualizing gross vegetation structure
variation at a regional to national scale, but the vegetation state and
community classes in ESDs represent potential and functional attributes and are
more useful for scenario-building, assessment, and the generation of monitoring
designs and monitoring hypotheses at landscape scales."
I hope this is of help.
Thanks,
Leonard Jolley Ph.D.
Rangeland Ecologist
Resource Inventory and Assessment Division
USDA Natural Resources Conservation Service
Beltsville, MD 20705
(301) 504-2344
-----Original Message-----
From: Ecological Society of America: grants, jobs, news on
behalf of William Adair
Sent: Wed 1/24/2007 7:05 PM
To: [email protected]
Cc:
Subject: Re: Ecological Sites vs. Ecological Systems
Hello Susan,
The two approaches were developed separately and somewhat
independently, and
(to my knowledge) there is no explicit hierarchy linking the
two. I'm not
aware of any formal (or "official") methods that have been
proposed for
translating Ecological Sites into Ecological Systems, or vice
versa.
------
The NRCS Ecological Sites concept is very site-specific. I
have been told
that this manuscript provides the foundation for the NRCS
Ecological Sites
concept:
DYKSTERHUIS, E.J. - Condition and management of rangeland based
on
quantitative ecology. J. Range Mgmt., 1949, 2: 104-115.
Personally, I've found that every range conservationist seems
to have
his/her own idea of what the term "Ecological Sites" means.
The Grazing Lands Technology Institute's "Interpreting
Indicators of
Rangeland Health" is probably the best place to go to see how
the NRCS
Ecological Sites concept is (supposed to be) applied:
http://www.glti.nrcs.usda.gov/
------
In contrast, NatureServe developed the Ecological Systems
concept as an
intermediate level in the Federal Geographic Data Committee
(FGDC) National
Vegetation Classification System (NVC) hierarchy. This
development was in
part inspired by problems that arose when folks (like our lab)
tried to map
NVC Alliances and Associations across broad regions with remote
sensing
data. You can access the document that describes the
Ecological System
concept here:
http://www.natureserve.org/publications/usEcologicalsystems.jsp
------
For a good general overview of vegetation and land cover
classification
concepts, I encourage you to check out the material on the ESA
Panel on
Vegetation Classification's web page:
http://www.esa.org/vegweb/
Please note that the NVC standard is likely to change soon.
This document
summarizes some of the proposed changes:
http://www.esapubs.org/bulletin/current/webpdfs_jan07/other1.pdf
The draft mentioned on that website is located here:
http://www.bio.unc.edu/faculty/peet/lab/temp/FGDCDraftStd_Aug2006.pdf
Hope this helps...
happy trails
bill adair
Utah State University Remote Sensing / GIS Laboratories
Chaos is not just a theory -- it's a way of life
-----Original Message-----
From: Ecological Society of America: grants, jobs, news
[mailto:[EMAIL PROTECTED] On Behalf Of
=?iso-8859-1?Q?Susan_Geer?=
Sent: Wednesday, January 24, 2007 3:22 PM
To: [email protected]
Subject: Ecological Sites vs. Ecological Systems
What is the relationship of the "Ecological Site", a term used
by the NRCS
and BLM that is based on soil maps but includes vegetation
characteristics
to the "Ecological System", a term used by Natureserve? Is
there a
hierarchy, and can one be converted to the other? Thanks.
