Inventory and Survey Methods for Nonindigenous Plant Species (PDF)

Chapter 5 • Tiered Sampling Method: Nevada’s Protocolbeen simplified to the current protocol for use across thestate by any management group, thereby ensuring someconsistency and confidence in the collected NIS data.The following issues must be considered when using thismethod.1. Depending on the resources allocated for the inventory/survey,decide upon the amount of time available andthe acceptable level of confidence (the probability that allof the NIS populations within a given area will be found).Determine the inputs necessary to achieve a level ofconfidence indicating that most of the NIS will be found.Inputs can be various types of resources such as funding,labor, and equipment, or they can be less tangible inputssuch as knowledge about the area. No one is ever ableto find every single NIS, even though that might be theinitial goal. It is inevitable that individual NIS and someNIS patches will be missed, due to such factors as the sizeand growth stage of the plant, as well as the concentrationlevel of the observer. The more closely the protocol isfollowed and the more intense the inventory/survey, thesmaller the size of NIS patches that will be found and thegreater the chance of finding all patches in the designatedarea.2. Identify all NIS of concern that will be targeted fordetection.3. Understand the dispersal mechanisms of each NIS.4. Select areas to sample that are easily definable by landscapecriteria, such as a watershed or valley. This allowsthe inventory/survey crew to define and record more easilywhere NIS were or were not inventoried/surveyed for.5. Select a global positioning system (GPS) and databaselibrary (data dictionary) that is compatible with theGIS being used. In our example the GPS library has tobe compatible with the centralized GIS of the state ofNevada.6. Ensure that fields are available in the GPS databaselibrary for the surveyor to note the size and location ofNIS patches, NIS name and density, and any other dataneeded for planning future management and monitoringactivities (Table 1). We use library attributes referencedin the Guidelines for Terrestrial Noxious Weed Mapping andInventory in Idaho (Bruno 1999).Tier IThe goal of the Tier I method is to inventory specifiedareas and locate all populations of target species. Weassume NIS are most likely to become established neardisturbed or wet areas, transportation systems, and aroundwaterways or water bodies, so we prioritize these areasfor our Tier I inventory. When infestations are found, thelocation (Universal Transverse Mercator [UTM] coordinatesor latitude/longitude) is stored in a GPS as a point, line, orarea feature (polygon). The steps in the Tier I method areoutlined below.Table 1. Information included in the Idaho data dictionary and used in Nevada.GPS Library AttributesGPS dataSurvey dateSurveyorWeed codeCommon nameGenusSpeciesSize in square feetAcres (optional)Cover classWetnessDistance to road less than 150 feetAccessSuggested control measuresCommentsFormatYes or noEnter dateEnter nameFrom the WSSA weed ID codesCommonly used weed nameGenus of weed locatedSpecies of weed locatedEstimated size of weed infestation if small in sizeEstimated number of acres of weedEstimate of amount of ground covered by the weedDistance to standing waterIs the site within 150 feet of the road: yes or noHow the area can be accessed (foot, vehicle, ATV, etc.)Add notesAdd notes43Inventory and Survey Methods for Nonindigenous Plant Species