PART 1HOW EARTH WORKSThis section includes examples of GIS helping scientists to gain better insight and understanding of Earth process and function in natural science fields such as geology, ecology, oceanography, climatology, cryospheric science, and conservation biology. By way of reliable, verifiable spatial analysis and visualization, GIS helps physical scientists answer a myriad of questions about spatial patterns in the natural environment (geosphere, biosphere, hydrosphere, atmosphere) and what process is responsible for those patterns. GIS is also a modern platform for the open sharing of data and for compelling science communication at a multiple of scales (e.g., individual researcher, lab workgroup, multi-department, multi-university, university-to-agency collaboration, and citizen engagement).

The Elwahs River’s watershed in Washington State. Hundreds of thousands of salmon swam in the Elwha’s pristine waters until the early twentieth century. Loggers harvesting the region’s rich, old-growth forests eyed the Elwha—with its rushing waters and narrow canyon—as an ideal source of hydropower.

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GLOBALECOSYSTEMMAPPINGUsing advanced geospatial technology, a team of public- and private-sector scientists have created a high-resolution, standardized, and data-derived map of the world’s ecosystems—a global dataset useful for studying the impacts of climate change, as well as the economic and noneconomic value these ecosystems provide.

By Roger Sayre, US Geological Survey

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Global Ecosystem Mapping 5

This map of the world synthesizes data on climate, landforms, geology, and vegetation to capture the total variety of ecological land units (ELUs) on the planet’s land masses. There were 3,639 distinct land units identified.

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INTRODUCTIONAnyone who is seriously interested in geography is probably familiar with an unassuming, spiral-bound, calendar-format book called Geography for Life: National Geography Standards,1 now in its second edition. It contains the geography curriculum for students in the fourth, eighth, and twelfth grades and is a valuable read for anyone, educators and noneducators alike, who wants to know what the geographically informed person needs to know. The book opens with an emphasis on two fundamental geographic perspectives that can and should always be taken into account when thinking about life and the earth: the spatial perspective and the ecological perspective.

It is interesting and refreshing to finally see these two geographic perspectives as primary. To have those perspectives spelled out so clearly in the National Geography Standards is powerful and affirmational to the growing ranks of spatial ecologists trying to apply “The Science of Where” to “The Ecology of Earth.” In that grand and evolving synthesis, there are many important questions to be asked, many thorny problems to be tackled, and fortunately, many opportunities to make a difference for the betterment of society and the planet. One of those opportunities is the conservation and sustainable development of our global ecosystems.

Ecosystems give us, as humans, goods (e.g., food, water, fiber, fuel, etc.) and services (e.g., water quality maintenance, flood control, carbon sequestration) that are critical for our survival. If ecosystems are allowed to persist on the planet, they will continue to provide those goods and services to future generations. This existential dependence of humans on natural ecosystems is recognized in the Sustainable

Development Goals (SDGs)2 that global leaders adopted in 2015 as part of the United Nations 2030 Agenda for Sustainable Development. Three of the 17 SDGs focus specifically on the protection of different kinds of terrestrial ecosystems (SDG 15), coastal and marine ecosystems (SDG 14), and freshwater ecosystems (SDG 6).

This well-organized set of curriculum standards is designed to stimulate the geographic imagina-tion of students and is a practical resource for directing teachers how to present various issues in the field of geography. The vast majority of states have incorporated parts or all of the 18 geography standards into their state standards. Geography for Life has sold nearly 100,000 cop-ies, and numerous textbooks have incorporated the standards into lesson plans and exercises.

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The Sustainable Development Goals, otherwise known as the Global Goals, are a universal call to action to end poverty, protect the planet, and ensure that all people enjoy peace and prosperity. The crucial need for humans to improve the conservation and sustain-able development of global ecosystems is recognized in several of the SDGs that countries have adopted through a United Nations resolution.

Terrestrial: by 2020, ensure the conserva-tion, restoration, and sustainable use of ter-restrial and inland freshwater ecosystems and their services, in particular, forests, wetlands, mountains, and drylands. By 2030, ensure the conservation of mountain ecosystems, including their biodiversity, in order to enhance their capacity to provide benefits that are essential for sustainable development.

Marine: by 2020, sustainably manage and protect marine and coastal ecosystems to avoid significant adverse impacts— including by strengthening their resilience—and take action for their resto-ration to achieve healthy and productive oceans. By 2020, conserve at least 10 percent of coastal and marine areas, con-sistent with national and international law, on the basis of the best available scientific information.

Freshwater: by 2020, protect and restore water-related ecosystems, including mountains, forests, wetlands, rivers, aqui-fers, and lakes.

THE NEED FOR GLOBAL ECOSYSTEMS MAPS

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—from GEOSS Task GI-14: Global Ecosystem Mapping

TASK: Develop a standardized, robust, and practical global ecosystems classification and map for the planet’s terrestrial, freshwater, and marine ecosystems, along with a web- enabled framework of data, tools, and work-flows that will be used to create and publish authoritative physiographic and ecological land classifications of the earth’s surface at several scales.

It is clear by UN mandate that the need to protect ecosystems from threats is key to the sustainability of human society. It is not so clear, however, what ecosystems are, where they are located on the planet, what condition they are currently in, what may be threatening them, and how vulnerable they are to those threats. The consequences of failing to protect these ecosystems are also unclear. Understanding ecosystems is a challenge. Current and future generations of students in the United States will be increasingly knowledgeable about ecosystems, thanks in part to National Geography Standard No. 8 on “the characteristics and spatial distribution of ecosystems and biomes on Earth’s surface.”

However, ecosystems are fragile, and they are disappearing from the planet at unprecedented rates.4 That fragility is one reason the Group on Earth Observations (GEO,5 an intergovernmental consortium of about 200 nations and organizations) has commissioned the development of standardized, robust, and management-practical global ecosystem maps for terrestrial, freshwater, and marine environments. The US Geological Survey (USGS), with its institutional prioritization of the ecological perspective as a foundation of its overall science strategy,6 was asked to lead that task and quickly turned to Esri for support with the spatial perspective.

Macroclimate

Topoclimate

Biota

Landform

Surface water

Soils

Groundwater

Bedrock

EC

OS

YS

TE

M

Ecosystems are defined as areas of unique physical environment settings and biological assemblages. We can envision an ecosystem at any given point on Earth’s surface as a vertical integration of its structural elements. So a terrestrial ecosystem is defined, for example, by its combination of climate regime, land-forms, organisms, substrate, and so on (the ecological perspective).3

The USGS and Esri joined ecosystem experts from around the world to rapidly advance the science of ecosystems geography. In a successful and productive public, private, academic, and nongovernmental organization (NGO) partnership, the Global Ecosystem Mapping (GEM) team produced several first-of-their-kind, high-spatial-resolution, globally comprehensive ecosystem maps for terrestrial, freshwater, and marine domains. The team is approaching this task with the simple premise that Earth is indeed a multifaceted gem of sorts (in the shape of an oblate spheroid, of course) and that the facets of the gem represent ecosystems on the land and sea surfaces. Now known as “facet mapping,” this innovative approach breaks the environment down into the smallest mappable terrestrial ecosystems, called ecological facets, or EFs.

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Global Ecosystem Mapping 9

The analogy of ecosystems as gem facets breaks down when considering uniqueness. The facets of an actual gemstone need to be identical and geometrically perfect, and dissimilar facets may render the gem flawed. Ecosystem facets, on the other hand, are distinguished from one another by their differences in pattern. We distinguish ecosystems based on their unique physical environment settings and biological assemblages, and how they change over time. We envision an ecosystem at any given point in time as a vertical integration of its structural elements. So a terrestrial ecosystem is defined, for example, by its combination of climate regime, landforms, organisms, substrate, and so on (the ecological perspective).

Thymine Bioclimate

Organismal DNA Ecosystems “DNA”

Adenine Landform

Guanine Lithology

Cytosine Land cover

The way that the four nucleotides combine determines whether the organism is a human, butterfly, rhinoceros, Escherichia coli (E. coli), and so on.

The way that the four ecological features combine determines whether the ecosystem is a tropical savanna, temperate conifer forest, salt bush playa, arctic tundra, and so on.

As the structural elements of ecosystems change over space (the spatial perspective), so then does the ecosystem itself change over space. For anyone familiar with the basic workings of DNA, this idea is a little like taking a Mendelian genetic approach to ecosystems and thinking of ecosystem variation as an expression of a kind of “ecological DNA.” Global ELUs were mapped as distinct combinations of climate, landform, lithology, and land cover. These four inputs were each mapped for the planet as individual layers, which were then stacked up in a GIS and spatially combined into one global data layer at a spatial resolution of 250 m.

The GEM team has mapped ecological land units using the approach of identifying and mapping unique physical environments and their associat-ed biological assemblages as distinct ecosystems. The published ELU work7 and the later ecological marine unit (EMU) work8 were scientifically rigorous, globally comprehensive, and high spatial resolution, producing state-of-the-art characterizations of global ecological environments.

MAPPING APPROACH

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This analysis produced a staggering number (106,959) of ecological facets, each one a distinct combination of classes from each of the four input layers. To reduce this complexity, the 100,000+ facets were generalized into 3,639 ELUs. The map of global ELUs was presented using an “orange peel” (Goode’s homolosine) map projection, and advanced cartographic techniques made the terrain visually palpable with colors that reflect wet/dry and hot/cold climates.

ELUs are mapped as distinct physical environments and associated vegetation. The layers—global bioclimates, global landforms, global geology, and global land cover—are first mapped individually and then combined in a GIS to create the specific ELU.

ANDROY REGION, SOUTHERN MADAGA SCAR9

Bioclimate

EXAMPLE: HOT, DRY PLAINS ON

UNCONSOLIDATED SEDIMENT WITH SHRUBLANDS

Landform

Lithology

Land cover

Macroclimate

Topoclimate

Biota

Landform

Surface water

Soils

Groundwater

Bedrock

ECOLOGICAL L AND UNITS The ELU map contains 3,639 distinct ELU units, too com-plex for a simple legend. Instead, the inventory at left shows all possible combina-tions of the ELU input layers, and their color assignments. To interpret the diagram, first find the intersection of the temperature and mois-ture classes, and then select the appropriate column for landform, either plains, hills, or mountains. The submatrix of lithology (rows) against land cover (columns) is then presented, and the combi-nation of lithology and land cover is then selected.

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