Tag Archives: endangered species

Viewing biodiversity through the ecoregional lens

The Nature Conservancy’s Atlas of Global Conservation is a fabulous resource for understanding biological diversity. Scientists have divided up the world into more than 1,000 ecoregions and analyzed how they compare across dozens of measures.

I’ve used data from TNC’s atlas to create a slide deck that illustrates patterns in species richness and threats to biodiversity, with a focus on the United States and American West. Below is a video of the PowerPoint, which you can download at the bottom of this post.

Visualizing biodiversity through the lens of ecoregions from EcoWest on Vimeo.

Biome basics

Before we get to ecoregions, let me first note a broader way that TNC and others classify the natural world: biomes. An area’s climate more or less determines what types of plants can grow, and at the highest level we can classify the planet’s land masses according to the predominant vegetation, or lack thereof. There are 16 terrestrial biomes, ranging from snow and tundra to tropical forests.

The map below (click to enlarge) shows the biomes found in the United States. Much of the interior West is dominated by desert and xeric (dry) shrublands, but the higher elevations support temperate conifer forests. California has Mediterranean forests along much of its coast and the Sierra Foothills. There’s a bit of subtropical forest in the mountains of Southeast Arizona and temperate broadleaf forest in Oregon’s Coastal Range.

United States biomes

As with temperature, rainfall, and elevation, there is more uniformity in the biomes found in the East than the West. Look, for example, at how many different types of communities are found in California, or how isolated mountains in the Great Basin create little biome islands.

The United States actually leads the world in the number of biomes and smaller ecoregions within its borders, even exceeding countries that are much larger in size, as shown in the graphic below.

United States biomes and ecoregions

So it’s no surprise that the United States also ranks high in species diversity. In the graphic below, blue bars show the number of species by type. Orange diamonds show what percent of the world’s species are found in the United States and the number in parenthesis in the labels indicate the U.S. ranking worldwide. The highest levels of diversity for several groups are found in the United States, including freshwater mussels, freshwater snails, and crayfishes; several other groups, such as freshwater fishes and gymnosperms, are also well represented here.

United States ranks high in species diversity

Analyzing ecoregions

A more fine-grained view than biomes classifies the terrestrial world into 825 unique ecoregions. These areas are sort of like ecological neighborhoods with similar habitat. Below is a close-up of the American West. If you were to drive through several ecoregions on an interstate road trip, you’d notice the differences simply by looking out the window.

Ecoregions of the American West

TNC’s atlas also analyzes the planet according to its 426 freshwater ecoregions. Each of the regions has a unique collection of aquatic species and freshwater habitats. The map below shows the West’s two-dozen or so freshwater ecoregions, which generally correspond to the boundaries of important river basins.

Freshwater ecoregions of the American West

Dozens of biodiversity metrics

TNC’s atlas offers dozens and dozens of layers of geographic information by terrestrial, freshwater, and marine ecoregion. The deck that you can download at the bottom of this post has 71 slides, with views of both the world and United States.

To give you a taste of what’s available, here’s a summary of three slides.

1) Species diversity is greatest around the equator

One way to describe biodiversity is to look at the evolutionary distinctiveness of species in a given location. The map below shows the phylogenetic diversity of terrestrial vertebrate species (animals with a backbone). Phylogenetics is a measure of how closely related a group of species is. An ecoregion with high phylogenetic diversity has species that are more distinct from one another (see this summary and this paper for more on the measure).

In general, measures of species diversity are greater at lower latitudes due to the past effects of Ice Age glaciation at higher latitudes and the configuration of islands and other landforms on the Earth, both past and present. In the West, phylogenetic diversity of vertebrate species tends to be highest in the desert Southwest.

Phylogenetic diversity of species

2) Hotspots for threatened animals 

The analysis and conservation of biodiversity often focuses on those species most at risk of extinction. The map below shows the number of globally threatened animals by terrestrial ecoregion. Threatened species are those listed by the International Union for the Conservation of Nature’s Red List as vulnerable, endangered, or critically endangered. Globally, some of the greatest concentrations of threatened vertebrates are in South America and Southeast Asia. About half of the threatened animals are reptiles and amphibians, one quarter are mammals, and one quarter are birds. In the United States, the Southwest, the foothills around California’s Central Valley, the Southeast, and the Appalachians have the most threatened animals.

Number of globally threatened animals

3) Plenty of plants in arid American West

The map below shows the number of plant species by terrestrial ecoregion. Worldwide, there are more than 420,000 of the so-called higher order plants: trees, vines, grasses, fruits, vegetables, and legumes. Deserts and arid lands typically have fewer plant species, while tropical rainforests have the most. But in North America, some drier parts of the inland West actually have more plant species than wetter climes along the coast. Compare, for example, the Great Basin in Nevada to Washington.

Number of plant species

Those are just a few of the slides that I found most interesting. I’d be curious to hear from readers if they spot other patterns.

Data sources

To create the maps, I downloaded the GIS data from Data Basin (a search query for “Hoekstra,” as in atlas lead author and EcoWest advisor Jon Hoekstra, will return all the layers).

I highly recommend the book form of TNC’s atlas, which taught me a ton about biodiversity around the globe.

See this page for more background on ecoregions from WWF.


EcoWest’s mission is to analyze, visualize, and share data on environmental trends in the North American West. Please subscribe to our RSS feed, opt-in for email updates, follow us on Twitter, or like us on Facebook.

Timber harvest falls in national forests

Logging on national forests, many of them located in the West, is a shadow of its former self. One of the clearest trends we found in our research was the decline in the timber harvest reported by the U.S. Forest Service, as shown in the graphic below (click to enlarge) and on our forestry dashboard.

Forest service harvest

Prior to creation of the Forest Service in 1905, the activity was largely unregulated in the West. After World War II, harvest rates increased significantly, but starting in the late 1970s, environmental regulations and international competition led to dramatic decreases in the amount of timber coming off public lands. Passage of the National Forest Management Act of 1976 and restrictions related to the spotted owl in the 1990s led to major reductions in clear-cutting and other harmful practices.

Interactive dashboard from Headwaters

To learn more about public lands logging, check out the great dashboard that Headwaters Economics has developed. Although the data only goes back to 1980, the dashboard illustrates the timber harvest in each state, national forest, and U.S. Forest Service region.

In the screenshot below, I’ve highlighted Oregon’s Willamette National Forest. You can see a pretty stunning drop in logging starting around 1990, which is mirrored in other national forests in the region.

Source: Headwaters Economics
Source: Headwaters Economics

I was curious whether the timber harvest had also fallen as precipitously in places where there aren’t any spotted owls. The screenshot below highlights logging on national forests in Montana, which also declined, but not as sharply as in the West Coast states.

Source: Headwaters Economics
Source: Headwaters Economics

National forests aren’t the only places where logging takes place in the West. Especially along the Pacific Coast, there’s a ton of private and state land that’s actively logged. Some timber harvests also take place on tribal and BLM land. While national forests account for a big piece of the pie, it would be interesting to see whether the same trends are playing out on other lands in the West.

Data sources

The U.S. Forest Service provides historical data on harvests in this document and on this page. Headwaters Economics offers free downloads of the data in its interactive dashboard and provides more details on the data here.


EcoWest’s mission is to analyze, visualize, and share data on environmental trends in the North American West. Please subscribe to our RSS feed, opt-in for email updates, follow us on Twitter, or like us on Facebook.

Trends in endangered species listings

To list or not to list?

That’s the key question facing the U.S. Fish and Wildlife Service when it comes to endangered species.  More than 1,300 plants and animals have been granted federal protection and these so-called listed species are embroiled in practically every Western environmental issue. The Endangered Species Act (ESA) has real teeth and it’s often the biggest hammer in environmentalists’ toolbox.

In this set of slides, I show where federally protected species live and review the history of ESA listings.

Trends in endangered species listings from EcoWest on Vimeo.

Endangered species are found throughout the country, but they tend to be concentrated in a few hotspots. The graphic below, from NatureServe, depicts how many listed threatened and endangered species are found in each county. Hawaii, the Pacific Coast, the Southwest, Appalachia, and Florida stand out for their large number of listed species, but many U.S. counties, especially in the Midwest, have no threatened or endangered species.

Species map

The number of listed species might seem like a useful barometer for tracking the status of biodiversity, but it’s an imperfect metric at best. Species are supposed to be added to the list solely on the basis of science and biologists’ assessment of their imperilment, even if doing so would derail development or impose steep economic costs. In reality, several studies have found that politics frequently intrudes in the listing process. See, for example, my book Endangered: Biodiversity on the Brink, and a 1990 book by Richard Tobin (no relation),  The Expendable Future: U.S. Politics and the Protection of Biological Diversity.

In its first term, the Obama administration has listed more species per year than George W. Bush’s administration, but considerably fewer than during the Clinton administration. Looking at the rate of species listings says as much about the political appetite for such regulatory moves as it does about the status of the nation’s biodiversity.

The ESA gives citizens the ability to petition the federal government to add a new species to the list and some environmental groups, such as the Center for Biological Diversity and WildEarth Guardians, frequently make these requests. Fish and Wildlife is obligated to evaluate these petitions and decide whether a species should be listed, but with limited resources the agency can only process so many petitions. ESA opponents in Congress and elsewhere have figured out that by limiting this listing budget, they can constrict the pipeline of new species gaining federal protection.

Candidates in regulatory purgatory

The result is a gaping loophole that allows the government to declare a species’ listing as biologically “warranted but precluded” by budget constraints. Fish and Wildlife is only supposed to use this exception if “expeditious progress is being made to add qualified species” to the endangered club. In reality, the exception has become an all-too-convenient way for the government to abdicate its responsibilities under the ESA. I liken it to creating a long, slow-moving line for species to get aboard our legislative Noah’s Ark.

At least 24 species have blinked out while in the listing pipeline and the backlog of candidate species was the subject of recent litigation.  The Obama administration has made some progress in reducing the number of candidates from about 250 at the start of his first term to 192 in November 2012. Candidate species, like listed species, are found throughout the country, but they’re concentrated in Western and Southern states.

The number of listed species is bound to keep rising because only 20 have been declared recovered and no longer in need of ESA protection. In 18 cases, the government decided the original listing was in error, often because of taxonomic changes or the discovery of new populations. A species protected by the ESA has been declared extinct only nine times over the past four decades, which is pretty impressive given that many plants and animals only receive ESA protection after they’ve been driven to the brink.


Data sources

Fish and Wildlife’s ESA site is the go-to source for information on endangered species. I’ve also found Precious Heritage: The Status of Biodiversity in the United States to be an extremely helpful resource. The Nature Conservancy and NatureServe make some of the book’s figures available here.

If you’d like to explore some of this data further, I’ve built a state-by-state dashboard that shows the number of listed, candidate, and extinct species.

EcoWest’s mission is to analyze, visualize, and share data on environmental trends in the North American West. Please subscribe to our RSS feed, opt-in for email updates, or follow us on Twitter.