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Biological Data Gateway: Introduction
Biology is a truly interdisciplinary science, especially when it comes to evaluating living resources at map-levelArrow arum plants growing in a river marsh scales. Most broadly, it is helpful to think of the mapped biological data you will find in the National Atlas as falling into three broad categories of information.

The first of these is species, both plant and animal. Maps for a wide variety of species exist, some delineating distribution, some detailing abundance, and some demonstrating seasonal ranges. Other maps provide long-range views of how species populations and habitats have changed across recent years or even decades.

Biologists and ecologists think of the second category, places, in two distinct ways. Ecoregions, as the term itself suggests, are defined regionally. Ecoregions map of the conterminous USAlong with the land cover and soil conditions that contribute to their identities, geographical placement upon the continent itself is a primary component in distinguishing one ecoregion from another. Ecosystems, on the other hand, are habitat and community types that can occur, with some degree of variation, in various regions. Wetlands, for instance, are widespread and can be found in all 50 States.

Third, there are special issues. Something of a catchall category, special issues cut across place and species considerations to focus on problems of special concern. Invasive species, endangered species, biodiversity, contaminants, climate change, and wildlife mortality have been identified by the Nation's ecologists and biologists as among the most pressing challenges confronting species and habitats today.

Biological Data Gateway: Species
 Chesapeake Bay and Watershed map Although trained scientists play a much more important role today than they did when Thomas Jefferson called for the first national inventory of American flora and fauna, citizen naturalists have managed to significantly preserve their roles in such surveys. This is especially the case when it comes to the job of collecting data about birds, butterflies, and moths. Each year, thousands of ordinary citizens contribute their time and expertise to such studies and provide much of the data that allow us to better understand the numbers and habits of these species groups.

Swamppink (Hellonias bullata) An increased interest in the ecological sciences and the emergence of modern digital mapping techniques, however, have helped to create a level of geographically referenced species data undreamed of in Jefferson's day. For example, herpetologists - scientists who specialize in reptiles and amphibians - have created comprehensive range and abundance maps of numerous species since the 1950s. Likewise, national-scale maps exist for fishes, mammals, vegetation, and, in addition to moths and butterflies, other invertebrates as well.


Map Maker Samples
Forest Cover Types
Invasive Species:  Purple Loosestrife - Lythrum salicaria
Land Cover Characteristics
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Map Layers
Forest Cover Types
Invasive Species: Purple Loosestrife - Lythrum salicaria
Land Cover Characteristics
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Wall Maps
Forest Cover Types
National Wildlife Refuge System
Dynamic Maps
Invasive Species - Zebra Mussels
Vegetation Growth in the United States
General Information about Invasive Species
What's Buzzing with Africanized Honey Bees?
Zebra Mussels