<descriptor thcode="2"><thesaurus thcode="2" name="USGS Thesaurus" scope="Topics and methods of scientific study carried out by USGS, with product types, scientific disciplines, geologic time, and types of institutional structure and activities.  Broad and shallow, used to help people find scientific information." creator="U.S. Geological Survey" rights="Public domain" edition="2.0" date="2020-01-09" codetype="number" prefix="topic" uri="https://www2.usgs.gov/science/USGSThesaurus" tblname="term" nonpref="nonpref" relterm="relterm" root_code="1" contact="pschweitzer"><category><term thcode="25" code="29" name="distinct labels" parent="26" scope="Preferred labels (descriptor texts) are distinct within the thesaurus. A concept can be specified either by its unique identifier (code) or by the text of its descriptor."/><term thcode="25" code="16" name="hierarchical" parent="11" scope="Substantive broader-narrower relationships exist among the terms."/><term thcode="25" code="13" name="transitive" parent="12" scope="Narrower terms have an &quot;is a&quot; relationship with their broader terms, and generally can be described as part-of, type-of, or instance-of the broader term."/><term thcode="25" code="21" name="disciplines" parent="2" scope="Broad categories of human inquiry or activity, such as scientific disciplines."/><term thcode="25" code="20" name="methods" parent="2" scope="Actions taken to obtain or analyze information"/><term thcode="25" code="19" name="organizational functions" parent="2" scope="Things that organizations do, typically including various types of programs, projects, and services."/><term thcode="25" code="7" name="temporal" parent="2" scope="Terms indicate periods of time, such as chronostratigraphic units, named historical periods or intervals surrounding known historical events, or seasons."/><term thcode="25" code="5" name="theme" parent="2" scope="Terms indicate domains of human concern, such as scientific discipline, societal problems, or characteristics of earth, space, oceans, and living things."/><term thcode="25" code="29" name="distinct labels" parent="26" scope="Preferred labels (descriptor texts) are distinct within the thesaurus. A concept can be specified either by its unique identifier (code) or by the text of its descriptor."/><term thcode="25" code="16" name="hierarchical" parent="11" scope="Substantive broader-narrower relationships exist among the terms."/><term thcode="25" code="13" name="transitive" parent="12" scope="Narrower terms have an &quot;is a&quot; relationship with their broader terms, and generally can be described as part-of, type-of, or instance-of the broader term."/><term thcode="25" code="21" name="disciplines" parent="2" scope="Broad categories of human inquiry or activity, such as scientific disciplines."/><term thcode="25" code="20" name="methods" parent="2" scope="Actions taken to obtain or analyze information"/><term thcode="25" code="19" name="organizational functions" parent="2" scope="Things that organizations do, typically including various types of programs, projects, and services."/><term thcode="25" code="7" name="temporal" parent="2" scope="Terms indicate periods of time, such as chronostratigraphic units, named historical periods or intervals surrounding known historical events, or seasons."/><term thcode="25" code="5" name="theme" parent="2" scope="Terms indicate domains of human concern, such as scientific discipline, societal problems, or characteristics of earth, space, oceans, and living things."/></category><altlabel><altlabel>USGSThesaurus</altlabel><altlabel>USGSThesaurus</altlabel></altlabel></thesaurus><term thcode="2" code="317" name="ecosystem monitoring" parent="375" scope="Recording, evaluating, and actively intervening over time in the interaction of living and nonliving elements in a specific environment."/><uf><usefor name="dendroecology"><usewith><term thcode="2" code="1266" name="vegetation" parent="841" scope="Plant life or general plant cover in an area."/></usewith></usefor><usefor name="indicator species observation"/></uf><bt><term thcode="2" code="375" name="field inventory and monitoring" parent="376" scope="Repeated observation or sampling at a site, on a scheduled or event basis, for study and analysis.  In general, this category excludes sampling programs in which materials are obtained in the field and brought back to a laboratory for study and analysis."/><term thcode="2" code="376" name="field methods" parent="734" scope="Research procedures and instrumental means to measure, collect data and samples, and observe in the natural areas where the materials, phenomena, structures, or species being studied occur."/><term thcode="2" code="734" name="methods" parent="1" scope="Techniques, methods, procedures, or strategies for research, management, collection, or analysis of scientific information in USGS."/><term thcode="2" code="1" name="Categories" scope="Thematic terms for categorizing information resources.  This thesaurus is intended to support finding and understanding scientific information."/></bt><nt><term thcode="2" code="2299" name="biomarkers" parent="317" scope="Biochemical, physiological, morphological, or histopathological characteristics of organisms that signify exposure to contaminants.  Also used for biogeochemical measurements of rocks to detect biological origin."/><term thcode="2" code="2300" name="habitat suitability indices" parent="317" scope="Numerical values calculated for a given area representing the capacity of a habitat to support a given species, as the ratio of observed habitat conditions to optimum conditions."/><term thcode="2" code="672" name="long-term ecological monitoring" parent="317" scope="Data collection over a period of years or decades to assess changes in selected biological communities and habitats."/></nt><rt><term thcode="2" code="96" name="biogeography" parent="921" scope="The study of the geographic distributions of plants and animals."/><term thcode="2" code="107" name="biological population management" parent="776" scope="Judicious means of controlling or directing numbers and life conditions of organisms living in a specific locality to achieve a selected goal."/><term thcode="2" code="113" name="bioremediation" parent="980" scope="Use of biological methods, usually involving microorganisms, to break down or neutralize contaminants in soil, water, and wastes."/><term thcode="2" code="311" name="ecology" parent="650" scope="Study of the relations between living plants and animals and their environment."/><term thcode="2" code="316" name="ecosystem management" parent="776" scope="Means of controlling or directing human practices, species populations, and physical environment within an ecosystem to achieve a selected state of sustainability."/><term thcode="2" code="776" name="natural resource management" parent="689" scope="Using a combination of techniques to control or direct the use of resources and limit population size to reach a predetermined goal, such as sustainability."/><term thcode="2" code="921" name="population and community ecology" parent="1174" scope="Interactions of a single species (population) or an association of different species (community) occupying a particular region, including their biotic and abiotic environments."/><term thcode="2" code="978" name="relative abundance analysis" parent="189" scope="Determination of the percentage of individuals of one group in comparison to the total of all individuals in a given area."/><term thcode="2" code="980" name="remediation" parent="776" scope="Methods for decontaminating, reclaiming, and restoring natural resources or reducing the effects of hazards."/></rt></descriptor>