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Ancillary Data

Published May 19, 2011

Regions used for species modeling

The lower 48 states of the U.S. were divided into six regions for modeling purposes. Each of the ancillary data layers are split into these six regions and models were run within a region and regional model output were compiled to create a complete distribution model across a species range. The regions are based on grouped MRLC zones. The regions are shown on the map below. You can download the regional boundaries data layer here:

Select a region and then click on the links below to download the regional data layers. Regions used for species modeling

The lower 48 states of the U.S. were divided into six regions for modeling purposes.
Each of the ancillary data layers are split into these six regions and models were
run within a region and regional model output were compiled to create a complete
distribution model across a species range. The regions are based on grouped MRLC
zones. The regions are shown on the map below. You can download
the regional boundaries data layer here:

Select a region and then click on the links below to download the regional data
layers. Descriptions of the data layers follow the links.

regions

Region

Great Plains Northeast Northwest Upper Midwest Southeast Southwest

Hydrography (description)

Grid Name Salinity(s) Water Type(t) Velocity(v) Mask(n) Description
s0t1v0n0 All (0) Flowing (1) All (0) None (0) All types of flowing water with no masks
s0t1v0n1 All (0) Flowing (1) All (0) Standing (1) All types of flowing water with standing water masked out
s0t1v1n1 All (0) Flowing (1) Fast Only (1) Slow & standing (1) All types of fast flowing water with slow & standing water masked out
s0t1v2n0 All (0) Flowing (1) Slow Only (2) Fast (0) All types of slow flowing water with fast water masked out
s0t1v2n1 All (0) Flowing (1) Slow Only (2) Fast & standing (1) All types of slow flowing water with fast water & standing water masked out
s0t2v0n0 All (0) Standing (2) n/a (0) None (0) All types of standing (open) water with no masks
s0t2v0n1 All (0) Standing (2) n/a (0) Flowing (1) All types of standing (open) water with flowing water masked out
s0t3v0n0 All (0) Wet Veg (3) n/a (0) None (0) All types of wet veg with no masks
s1t1v0n0 Fresh (1) Flowing (1) All (0) Brackish standing water & brackish wet veg (0) Fresh, flowing water with brackish standing water and wet veg masked out
s1t1v0n1 Fresh (1) Flowing (1) All (0) All standing water & brackish wet veg (1) Fresh, flowing water with all standing water, and brackish wet veg masked out
s1t1v1n1 Fresh (1) Flowing (1) Fast Only (1) Slow & standing (1) Fresh, fast flowing water with slow water & standing water masked out
s1t1v2n0 Fresh (1) Flowing (1) Slow Only (2) Fast (0) Fresh, slow flowing water with fast water masked out
s1t1v2n1 Fresh (1) Flowing (1) Slow Only (2) Fast & standing (1) Fresh, slow flowing water with fast water & standing water masked out
s1t2v0n0 Fresh (1) Standing (2) n/a (0) Brackish flowing water & brackish wet veg (0) Fresh, standing water with brackish flowing water and wet veg masked out
s1t2v0n1 Fresh (1) Standing (2) n/a (0) All flowing water & brackish wet veg (1) Fresh, standing water with all flowing water and wet veg masked out
s1t3v0n0 Fresh (1) Wet Veg (3) n/a (0) Brackish (0) Fresh wet veg with brackish water masked out
s2t1v0n0 Brackish (2) Flowing (1) All (0) Fresh standing & fresh wet veg (0) Brackish flowing water with fresh standing water, & fresh wet veg masked out
s2t1v0n1 Brackish (2) Flowing (1) All (0) All standing water & fresh wet veg (1) Brackish flowing water with all standing water and fresh wet veg masked out
s2t2v0n0 Brackish (2) Standing (2) n/a (0) Fresh flowing & fresh wet veg (0) Brackish standing water with fresh flowing water & fresh wet veg masked out
s2t2v0n1 Brackish (2) Standing (2) n/a (0) All flowing water & fresh wet veg (1) Brackish standing water with all flowing water & fresh wet veg masked out
s2t3v0n0 Brackish (2) Wet Veg (3) n/a (0) Fresh standing, flowing, & wet veg (0) Brackish wet veg with fresh flowing, standing water, & wet veg masked out

Layer Descriptions

Human impact avoidance

Environments dominated by human disturbance such as roads, cities, and the constructed materials that support human habitation have profound effects on species. For most species, this data layer was used to exclude species from a portion of the landscape. However, some species respond favorably to human habitats, therefore this data layer was used in an inclusionary manner.

Model Report: If a species’ model uses the model variable for human impact avoidance, then downloading these ancillary data will provide the level of avoidance described below.

Level of avoidance

High – For species that are very intolerant of human disturbance. All portions of the landscape identified as being directly influenced by human disturbance are eliminated from the predicted distribution.

Medium -For species that are moderately intolerant of human disturbance. Only portions of the landscape identified as being highly or moderately influenced by human disturbance are eliminated from the predicted distribution.

Low – For species that are partially intolerant of human disturbance. Only portions of the landscape identified as being highly influenced by human disturbance are eliminated from the predicted distribution.

No selection of this parameter indicates the species’ model is not contingent on an index of human disturbance.

Elevation

Some species respond to environments directly related to altitudinal variation. Elevation (e.g., DEM) is easily implemented in spatial modeling by limiting the model to the minimum and maximum values explicitly stated in the literature. DEMs are utilized directly and are measured in meters above mean sea level.

Model Report: If a species’ model uses elevation as a model variable, then download the ancillary data for elevation.

Hydrographic information

Water and its location on the landscape is a very important aspect of species habitats. The source for hydrographic data was the USGS National Hydrography Dataset (NHD).

Model Report: If a species’ model report uses any of the hydrographic information, see the Hydrography table for the correct file. Each downloadable file in the table contains information with regards to salinity, water type, and velocity.

Types of water

Flowing Water – Flowing water represents hydrographic features such as streams, rivers, springs, seeps, ditches with moving water, etc.

Standing Water – Standing water represents hydrographic features such as lakes, ponds, reservoirs, bays, inlets, estuaries, ocean, ditches with stagnant water, etc.

Wet Vegetation – Wet vegetation represents hydrographic features such as swamps, marshes, Carolina bays, etc. This includes a collection of map units representing seasonally or tidally inundated woody and non-woody plants.

Salinity

Water salinity is a major factor when considering habitat conditions for many species. However, the dynamic and complex nature of water systems makes the development of a highly refined and reliable data layer challenging. Therefore, we developed three general categories to include in species habitat models for species requiring water.

Freshwater Only

Brackish/Salt Water Only

All Water (i.e., both brackish/salt water and freshwater)

Stream velocity

For some aquatic species, this is an important aspect of their habitat, such as oxygenation levels, presence of invertebrate prey, and amount of sediment within the water column and on streambed substrates. Stream velocity (i.e, stream gradient) was derived from a combination of streams and slopes calculated from a digital elevation model (DEM), which created three categories for stream gradient.

Slow Only – For species that require slow moving or almost stagnant sections of streams or rivers. Typically these are areas where the underlying topography is flat (0 % gradient).

Fast Only – For species that require high velocity sections of streams or rivers. Typically these are areas where the underlying topography is steep. A threshold of > 5 % gradient was used.

All Types – For species that can utilize either fast or slow sections of streams or rivers.

Distance into and from type of water

Distances from a type of water were:

>4000 m

2000-4000 m

1000-2000 m

500-1000 m

250-500 m

120-250 m

60-120 m

30-60 m

0-30 m

Distances into a type of water were:

0-30 m

30-60 m

60-120 m

120-250 m

250-500 m

500-1000 m

1000-2000 m

2000-4000 m

>4000 m

Land cover information

Land cover

The ecological systems mapped in the GAP National Land Cover Data were used as ‘map units’ to describe habitat types preferred by species.

Model Report: If a species’ model uses map units as a model variable, then download the ancillary data for land cover. Map units are designated as either primary or secondary. Primary maps units are defined as those ecological systems critical for a species’ reproduction and survival. Secondary map units are those ecological systems generally not critical for reproduction and survival, but typically are used in conjunction with primary map units for foraging, roosting, and/or sub-optimal nesting locations. Secondary map units are selected only when located within a specified distance from primary map units.

Patch Size

The type and size of clusters of habitat can be assessed with spatial modeling. We used patch size to indicate minimum amounts of contiguous habitat needed for a species. This variable requires the generation of cluster sizes in the actual modeling code during post processing. In other words, these model variables are not independent ancillary data layers.

Model Report: If a species’ model uses patch size, this variable is generated in the actual modeling code during post processing. Any cells that do not form a minimum contiguous patch are eliminated. There are no specific ancillary layers for this variable.

Contiguous Patch

Minimum size (ha) – This parameter is set using the most conservative values explicitly stated in the species literature.

Forest and Ecotone Habitats

The ecotone (i.e., edge) between forested and non-forested environments can be a critical aspect of habitat. We grouped map units into forested, non-forested, and shrubland/woodland land cover types to create unique data layers. These data layers can then be buffered at specified distances to identify species habitats. Aggregated map units can be compared and contrasted to identify areas of transition between these broad categories. They can also be used to identify core areas or contiguous blocks of similar type (i.e., interior) through buffering.

Forested map units included deciduous forest, evergreen forest, mixed forest, palustrine forested wetland, and estuarine forested wetland (Homer et al. 2004).

Non-forested map units were defined as water, pasture/hay, agricultural areas, urban/developed, marshes, beaches, etc.

Woodland/shrubland map units were defined as those ecological systems and land uses containing a majority of short, scrubby, woody vegetation or sparsely canopied treed vegetation (Homer et al. 2004).

Forest Edge

This data layer constitutes unique aggregations of forest and non-forest map units.

Model Report: If a species’ model uses “edge type” as a model variable, then download the ancillary data for forest edge.

Ecotone type and width

Forest/Open Ecotone Only – This data layer represents the transitional areas between forest and open, non-forested habitats.

Model Report: If a species’ model “edge type” is set as forest/open ecotone only, then download the ancillary data for for forest edge.

Forest/Open Ecotone + Woodlands/Shrublands – The forest/open only ecotone does not consider environments with sparse canopies or scrubby vegetation, therefore this data layer includes woodland and shrubland map units that would otherwise be ignored.

Model Report: If a species’ model “edge type” is set as forest/open ecotone + woodlands/shrublands , then download the ancillary data for forest/open ecotone + woodlands/shrublands.

Ecotone Width – This distance represents a symmetrically buffered edge. For example, an ecotone width of 500 meters includes 250 meters into forest and 250 meters into open.

Buffer Distances –

Distances into forest from forest edge: >4000, 4000, 2000, 1000, 500, 250, 120, 60, 30, and 0 meters

Distances away from forest edge: >4000, 4000, 2000, 1000, 500, 250, 120, 60, 30 and 0 meters

Model Report: If a species model uses ecotone width, this variable is applied to the corresponding ecotone(s) described above (see EcotoneType).