NY Terrestrial Invasive Species Prioritization Tool

Project Sponsor: New York State Department of Environmental Conservation
End Date: June 14, 2024


The goal of this project is to provide spatial information to help prioritize invasive species surveys and management efforts in terrestrial systems. With guidance from statewide partners, we developed a framework that scores the landscape based on ecological value, natural and protected areas, and risk of spread. These scores are displayed in an online map viewer that managers can use to guide terrestrial surveys and management priorities.

Launch the Prioritization Tool.

Project Need & Background

Invasive species are a crucial consideration in biodiversity conservation and natural resource management. In New York State, land managers actively monitor and manage invasive species to protect natural resources, with regional coordination from the Partnerships for Regional Invasive Species Management (PRISM).

Starting in 2016 NYNHP worked with a steering committee made up of conservation partners to develop a framework for scoring locations based on three main factors: Ecological Significance, Protected and Natural Areas, and Risk of Spread; culminating in a Comprehensive Score. These scores are calculated from statewide data layers and spatial models representing locations of rare species, significant natural communities, protected areas, invasive species, and anthropogenic stressors.

The framework and underlying data layers were updated in 2024, and the results are shared in an interactive online map interface where users view the comprehensive score and the three component scores for any location across the state. Areas with high comprehensive scores are generally intended to represent natural areas with high ecological value and a high potential for invasive species introduction and spread according to available information. Managers can use this tool to help prioritize where to direct resources for monitoring and managing invasive species.

This tool is intended to inform terrestrial invasive species work. For invasive species work in waterbodies, see the Aquatic Invasive Species Ponds & Lakes Vulnerability Prioritization.

Steering Committee

We developed this tool with input from a committee with representation from the following organizations. This group shaped the original framework and scoring of subcomponents in the original development of this analysis in 2016, and provided guidance and feedback on the 2024 update.

  • Bureau of Invasive Species and Ecosystem Health | Division of Lands and Forests | New York State Department of Environmental Conservation (NYSDEC)
  • New York Natural Heritage Program (NYNHP)
  • New York State Office of Parks, Recreation, and Historic Preservation (OPRHP)
  • Partnerships for Regional Invasive Species Management (PRISM)


The Comprehensive Score highlights where areas of high ecological value are at the highest risk from invasive species. It is calculated by adding together the Ecological Significance Score, the Risk of Spread Score, and the Protected and Natural Areas Score.

Ecological Significance Score:

The Ecological Significance score focuses on where habitat is suitable for rare plants and animals, as well as areas of known occurrence for rare plants, animals, and significant natural communities.

Ecological Significance Component Weight Data Source
Rare Species & Significant Natural Communities 55 New York Natural Heritage Progam (NYNHP)
Suitable Habitat for Rare Plants & Animals 35 New York Natural Heritage Progam (NYNHP)
  • Rare Species and Significant Natural Communities: These data are derived from New York Natural Heritage Program element occurrence data for terrestrial plants, animals, and natural communities that has been weighted to give higher scores to occurrences that are rarer, in better condition, and more recently observed. Natural community occurrences receive higher scores than plant or animal occurrences because they represent habitat for multiple species. To account for the highly skewed values in this data set, the data were square root transformed before being re-scaled (0-1) and weighted.
  • Suitable Habitat for Rare Plants and Animals: We used a set of habitat suitability models for rare terrestrial plants and animals tracked by the New York Natural Heritage Program. Habitat suitability models are a prediction of where in New York suitable habitat for a species might be, based on a classification algorithm (random forests), where we know the species already occurs, and the environmental conditions in those places. The map of suitability for each species was transformed into a binary model where a value of 1 represented suitable and 0 represented not suitable. Binary models for 344 terrestrial species were stacked together to create a map where higher values indicated habitat suitable for more rare species.

Risk of Spread Score:

The Risk of Spread score represents elements that are correlated with an increase in the risk of introduction or spread of terrestrial invasive species. The elements chosen are primarily associated with human-mediated spread of terrestrial invasives.

Risk of Spread Component Weight Data Source
Landscape Condition Assessment 35 New York Natural Heritage Progam (NYNHP)
Density of Invasive Species 10 NY iMapInvasives
Distance to Buildings 5 Microsoft
Distance to Trails 5 NYS GIS Clearinghouse
Distance to Campgrounds 5 NYS GIS Clearinghouse
  • Landscape Condition Assessment: The Landscape Condition Assessment is a model created by NYNHP that depicts presumed impacts from a suite of anthropogenic stressors (e.g., roads, urban and industrial development, and utility corridors) across the state. A sigmoid decay function was applied to each stressor to model the attenuation of ecological effects away from its footprint.
  • Density of Invasive Species: We used the confirmed presence data in iMapInvasives as of February 2024, for species on the Invasive Species Tier List for the state and/or any of the eight PRISMs. iMap polygon and polyline data were converted to points and combined with iMap point data. Points were thinned by species to 1 point per species per 100m. A kernel density analysis was run on these thinned points, at 30 meter resolution and with a maximum search distance of 2 km, calculating the density of known selected invasives per kilometer. To account for skew, these values were log transformed before being rescaled (0-1) and weighted.
  • Distance to buildings: Building polygons were taken from Microsoft Map’s US Building Footprints, which contains computer generated building footprints derived from satellite imagery. The score was inverted (1/(1+distance) so that the highest scores for risk were those closest to the buildings, and the score diminishes with distance away from the building.
  • Distance to Trails and Campgrounds: We calculated the distance to Trails and Campgrounds using Trails and Campground locations from the New York State GIS Clearinghouse. The score was inverted (1/(1+distance) so that the highest scores for risk were those closest to the stressors, and the score diminishes with distance away from the stressor.

Natural and Protected Areas Score:

The Natural and Protected Areas layer highlights habitat in New York that is classified as natural, as well as areas that are currently under an existing level of protection.

Natural & Protected Areas Component Weight Data Source
Protected Areas 15 New York Protected Areas Database (NYPAD)
Natural Land 5 National Landcover Dataset (NLCD 2021)
Riparian Areas 5 New York Natural Heritage Program (NYNHP)
  • Protected Areas: We used the New York Protected Areas Database (NYPAD) to represent areas under existing protection or conservation. We used the NYNHP Biodiversity Index (a statewide assessment of direct and indirect measures of biodiversity) as a proxy for the approximate habitat quality of each NYPAD parcel. NYPAD parcels were ranked according to the average Biodiversity Index value in each polygon, and then divided into 10 quantiles (groups with an equal number of polygons) based on those scores. All polygons in the same quantile received the same point values, with polygons in the highest quantile receiving the maximumvalue.
  • Natural Land: Natural Land was based on the land use classification of the 2021 National Landcover Dataset (NLCD), a 30 meter resolution product with 16 land use classes. All areas that were not classified as “developed” (classes 21, 22, 23, and 24) were included in the natural land component. All natural land received the same point value.
  • Riparian Areas: Healthy riparian habitat provides vital ecosystem services from flood mitigation to rare species habitat. We used the NYNHP riparian buffers, a variable width model of the riparian zone based on modeled 50 year flood height data and High Resolution flowlines from the USGS National Hydrography Dataset, to delineate the riparian zone. Riparian zones that did not intersect with natural land were removed and did not receive additional points.

Using the Prioritization Tool

  • The scores in this tool are unitless and not normally distributed. The score for a particular location should only be interpreted relative to the values seen across the state, region, or surrounding area (e.g. is the score at your location higher or lower than the surrounding area).
  • To view the scores for a particular location, click on the map and use the arrow keys at the bottom left of the pop-up to view each score. Read the text, note the percentile, and scroll down to view the histogram to interpret your score.
  • Use the Map Layers panel (bottom right) to adjust your map view:
    • Toggle layers on and off and view specific layers (note: for the prioritization score rasters, the topmost layer turned on is the one you will see).
    • Turn on the New York Protected Areas Database layer, and click on a parcel to see the average and range of scores in that parcel. Click the three dots next to this layer in the map layers list for more options, including applying filters.
    • To make a layer more transparent, click the three dots next to the layer in the list and select “increase transparency”.
  • Use the Swipe tool to efficiently swipe between two layers (see instructions in the interface for more information).
  • Use the Draw tool at the bottom right to mark up your map view and highlight key areas (note: this is purely for visualization purposes and will not be saved to the map or actionable with any layers).

The online tool is available at: https://experience.arcgis.com/experience/15438cfb42cd44519811de69218b25f7

June 26, 2024 | Updated June 28, 2024, 3:10 p.m.