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Geospatial Condition Analysis: A new tool to assess the condition of northeast terrestrial and aquatic habitats

The Nature Conservancy Eastern Conservation Science

Mark G. Anderson, Melissa Clark, Charles Ferree, Alexandra Jospe and Arlene Olivero Sheldon

How to Assess the Condition of the Mapped Terrestrial and Aquatic Habitats? Goal: To use the Northeast terrestrial and aquatic habitat maps to promote an understanding of biodiversity patterns across the region and facilitate interstate communications about habitats. The foundational classification work is described in the Northeast Terrestrial and Aquatic Habitat Guides, and this is the condition assessment of those habitats.

Condition Metrics

The metrics used in this report and accompanying toolset were selected to indicate the ecological condition of the terrestrial and aquatic habitats. They were selected in consultation with a group of Fish and Wildlife agency staff and represent the final set of prioritized metrics that emerged from a set of conference calls and meetings held in 2012. These metrics were limited to those that could be measured using existing datasets and that were consistently available at a regional scale covering all 13 states in the project area. A list of all metrics and their definitions is provided in the table below, and several examples are shown in the following maps.

Secured Lands Land that is permanently secured against conversion to development. This includes both designated and undesignated conservation lands intended for permanent securement.

Landscape Context Index The Landscape Context Index (LCI) quantifies the degree of human conversion of natural landcover in the immediate neighborhood of that cell on the landscape.

Local Connectedness An estimate of the degree of permeability, or conversely the degree of resistance surrounding each cell in the region. We summarized this metric into a habitat connectedness index.

Functional Connected Networks A connected network is defined as the set of stream and river segments bounded by fragmenting features (dams) and/or the top most extent of headwater streams. The total linear length of all segments in each connected network was calculated.

Road-Stream Crossings At each point when a road crosses a stream, manmade infrastructure allows the road to cross the stream. On small streams, these structures are often culverts, which frequently act as barriers to aquatic biota.

Category Name Definition

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Secured lands Amount of unit permanently maintained in a natural state

Local connectivity

An estimate of the degree of permeability, or conversely the degree of resistance, surrounding each cell in the region, summarized into a habitat connectedness index

Landscape context

The degree of human conversion of natural landcover in the immediate neighborhood of that cell on the landscape

Predicted development

The acres of a habitat predicted to be developed over the next 50 years, calculated within each unit

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Forest stand age

The proportion of various age classes of a forest or habitat type within its geographic range

Patch size The size of each contiguous patch of habitat, bounded by roads, development, agriculture or contrasting habitats

Core area Core area is the amount of interior habitat in the central region of a habitat patch. This sheltered secluded habitat is preferred by many species for breeding

Landscape complexity

An estimate of the number of micro-climates in a 100 acre area surrounding each cell of habitat, based on the variety of landforms, the elevation range, and the density of wetlands

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Impervious surfaces

Impervious surfaces are hard substrates like paved roads, parking lots, and roves. The amount of impervious surface in the upstream watershed of each reach was summarized

Riparian landcover

The riparian zone is the land area directly adjacent to a stream or river and subject to its influence. The different types of landcover (NLCD 2006) in the riparian zone within 100m on either side of mapped streams and rivers was summarized

Dam types and density

For each stream type, we summarized the number of dams, types of dams (hydroelectric, flood control, water supply, recreation, other), and density of dams per 100 miles of stream

Risk of flow alteration from dam water storage

The risk of flow alteration from dam water storage is expressed as the ratio of the volume of water being stored behind dams upstream to the mean annual flow volume expected in a reach, expressed as a percent

Network size A connected network is the set of stream and river segments bounded by fragmenting features (dams) and/or the topmost extent of headwater streams. We calculated the total linear length of all segments in each connected network

Road-stream crossings

At each point where a road crosses a stream, manmade infrastructure allows the road to cross the stream. On small streams, these structures are often culverts, that frequently act as barriers to aquatic biota

All Condition Metrics

Units of Analysis

Habitats do not occur in isolation, they interact and interplay with each other. Land conservation tends to happen on systems that contain patches of multiple habitats, because organizations often work to protect and manage tracts or multiple tracts of land. For these reasons we used patches of natural habitat bounded by roads as the basic unit for terrestrial analysis. The unit could consist of a single habitat type but more commonly it was a mosaic of several types. The condition metrics were attributed to these units. For aquatic systems, we used reaches with >1 mi2 drainage area as the basic unit of analysis. We also calculated metrics for the 100m riparian zone, the local catchment, and the total upstream catchment.

Major road-bounded blocks, delineated by double-width lines, were the backbone of the analysis in the terrestrial arena. The minor road-bounded blocks are shown with single-width roads, and the wetland complexes are shown in purple.

The analysis for aquatic habitats and conditions were based on stream reaches. Each river segment is referred to as a reach, and each of those reaches has a given catchment, as well as a cumulative upstream catchment, and a 100m riparian buffer.

Results: Geodatabase

One goal of this project was to create a database and toolset to allow users to locate terrestrial and aquatic habitats that meet certain condition metrics. Creating and compiling the information for this report was a monumental task. There are over 2 million habitat patches and over 200,000 miles of streams and rivers. We simplified this dataset to reportable units of road bounded blocks and stream reaches, each with many metrics. The data are presented in two geodatabases: one for input data, and one for the results.

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Results: Query Tool Even with a well-organized geodatabase, querying and analyzing information for hundreds of thousands of unit records across hundreds of fields can prove to be an overwhelming task. One solution is to create custom Arctoolbox queries to guide users through analysis of the database, without needing to know a lot about the field names, database structure, or data ranges. We created three sample queries to demonstrate the functionality of the tool.

In this drop down you can

either select "all states"

(which will query the entire

northeast) or select the

state using its postal abb.

that you wish to query.

In this drop down menu

you can select either "All

Habitats" or a specific

summary group upland

habitat type.

Core area is the amount of interior habitat in the central region of a habitat patch. This sheltered secluded habitat is preferred by many species for breeding. Many minor road bounded blocks in the region have no core area. The average core area for the blocks is 275 acres. The standard deviation is quite large at 3137 acres.

Forest stand age: The proportion of various age classes of a forest or habitat type within its geographic range. The mean stand age varies from 0 to 98.5 for the blocks in the region. The average stand age is 34 years in the region.

Navigate to the location of

the "Query_Terrestrial"

feature class in results

geodatabase on your

computer.

Local Connectedness: An estimate

of the degree of permeability, or

conversely the degree of resistance,

surrounding each cell in the region.

The range for Local Connectedness

is between 0 and 100 with 0 being

completely connected and 100

being completely developed. The

regional mean for this metric is 16.

The image on the left is a screenshot of the results window displayed after running the terrestrial forest query tool. On the right is a screenshot of the results as displayed in the map document.

Final Products 1. Final report including

condition metrics and results for the geospatial assessment 2. Final data for condition analysis 3. Website

Report

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Partial funding for this program is supported by a grant/cooperative agreement from the U.S. Department of the Interior, Fish and Wildlife Service.

For full legend, see report