Ecological Indicators for the Nation (2000) / Chapter Skim
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3 A Framework for Indicator Selection
3 A Framework for Indicator Selection
Pages 51-63
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From page 51... ...
But inadequate attention to the criteria that should guide development and use of all indicators has also contributed to the failure to achieve successful nationwide indicators. Many existing ecological indicators are applicable to only limited areas, to one type of ecosystem, or to the populations of one or a few species.
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From page 52... ...
The entries in this checklist, reviewed over the remainder of this chapter, are general importance; conceptual basis; reliability; temporal and spatial scales of applicability; statistical properties; data requirements; necessary skills of collectors of the data; data quality control, archiving, and access; robustness; international compatibility; and cost-effectiveness. General Importance Does the indicator tell us about changes in the primary ecological and biogeochemical processes described in the committee's conceptual model?
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From page 53... ...
To determine what an indicator indicates, the kinds of data needed to compute it, and how changes in it should be interpreted, the temporal and spatial scales of the processes measured by the indicator need to be clear (Peterson and Parker 1998~. Much about an indicator's relevant spatial scale is shown by the scope of the data used to compute the
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From page 54... ...
Spatial statistical patterns might also serve as indicators of spatial qualities, such as landscape heterogeneity or habitat diversity. The primary problem with spatial statistics is their requirement for extensive input data.
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From page 55... ...
1991~. Ecosystems may change very slowly, in response to factors such as changing climate, soil properties, and evolutionary changes in species; moderately slowly, as vegetation succession occurs and species ranges change; or suddenly, in response to disturbances, either natural (e.g., fire, storm, or disease)
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From page 56... ...
Where possible, it is also desirable to establish the past states of the system through historical and paleoecological studies that provide baselines for a program of physical, chemical, and biological monitoring. Those properties of ecosystem structure and functioning that paleoecological studies have identified as significant indicators of change are prime candidates for inclusion in current monitoring programs.
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From page 57... ...
Nevertheless, because long-term data sets are essential for detecting most environmental trends, technological changes must be incorporated into monitoring programs in ways that do not destroy the continuity of the data sets or render consistent interpretation of the changes impossible. As pointed out in Chapter 2, cross-calibration of measurements is especially important for remotely sensed data.
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From page 58... ...
For many years, the technological challenges of handling
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From page 59... ...
As both the hardware and software of instruments evolve, one must be able to identify and quantify degradation of instrument performance and offsets due to changing satellite orbital geometry or new technology, and correct for them before further analyses are attempted. DATA QUALITY CONTROL, ARCHIVING, AND ASSIGNMENT OF RESPONSIBILITIES Before any indicator is adopted, substantial thought and effort need to be given to issues of data quality control, data archiving, and data access.
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From page 60... ...
Therefore, the original investigators must document their methods carefully enough so that someone not associated with the original data collection can reproduce the original sampling or analytical protocols. This requirement is particularly important as methods and instrumentation change, so that data from early parts of the time series are quantifiably comparable to data from later parts of the same time series.
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From page 61... ...
Indicators of net ecosystem productivity or net primary productivity for any substantially large area are computed using some form of remotely sensed data combined with model simulations. The archive must encompass procedures to preserve not only the original data, but also the models that have been used to interpret or extrapolate from them.
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From page 62... ...
Implementing this function in the monitoring systems that provide data for indicators will be expensive. Experience with large field programs (e.g., the National Aeronautics and Space Administration's First ISLSCP {International Satellite Land Surface Climatology Project} Field Experiment {FIFE}, the National Aeronautics and Space Administration's Boreal Ecosystem Atmosphere Study {BOREAS}, the National Science Foundation's Long-Term Ecological Research {LTER} ~ suggests that the costs of the data systems that support intensive monitoring efforts can easily amount to 25 percent of the total budget.
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From page 63... ...
A FRAMEWORK FOR INDICATOR SELECTION 63 sive measurements from all parts of the nation as input. As we show in Chapter 5, if the data are archived in a highly disaggregated form, they can be used for indicators designed for local and regional levels as well.
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