SEE-U 2000: Biosphere 2 - Module 01

## Module 1: Introduction to Global Biomes

### Course Introduction

Welcome to the Summer Ecosystem Experiences for Undergraduates course! We hope that your time with us will be enriching, stimulating, and tremendously enjoyable. The essays that form the beginning of each module will cover general information that is relevant to the ideas and techniques that you will be covering in the activities for that module. Linked to these introductory texts will be one or more activities that you will complete while studying the information and techniques included in that module. The 16 modules in the course will be organized into four sections. Consult the syllabus for more information on how the curriculum is structured and the general curriculum overview page for a more in-depth description of the class, if you have not done so already.

We will cover two topics in this first introductory text: (1) how the class is organized and (2) what is a biome and what determines their distribution. So without further ado, let’s study some ecology!

### Ecological Hierarchy

The class is organized according to the ecological hierarchy. We will start toward the highest level (biomes), then jump to the lowest level (individuals and natural selection), and work our way back through populations and communities. We then consider key abiotic factors that influence ecological systems at all levels. The class concludes working back to the top, with a brief introduction to how to apply the principles that are laid out earlier in the class to conservation biology, starting at more local features and progressing up to those factors that affect the entire Earth.

### Biomes

Beginning at the beginning, let’s quickly answer the question of what determines the distribution and structure of biomes. Patterns that are only present at the global level combine to determine the distribution of biomes—chiefly latitude (distance from the Equator), altitude, wind and ocean currents, mountain systems, and continentality (distance from oceans). As latitude, altitude, and continentality increase, both average temperature and relative humidity tend to decrease. These in turn determine which biome will be present.

These features also combine to create temporary changes in the functioning of biomes, such as the El Niño / Southern Oscillation (ENSO) phenomenon. El Niño is a temporary relaxation of upwelling of deep ocean water in the eastern subtropical Pacific Ocean, but is related to changes in ocean and atmospheric circulation throughout the tropics (e.g., the Southern Oscillation). ENSO causes perturbations in climate in the low latitudes and more remotely in the mid-latitudes, impacting both oceanic and terrestrial biomes around the Earth. These transitory changes help us to better understand the forces that control the structure and function of biomes.

The three biomes included in the SEE-U program this year are all terrestrial and include the Temperate Deciduous Forest (as represented by the Eastern US Deciduous Forest), Subtropical Desert (Southwestern US Desert), and Moist Tropical Forest (Brazil’s Atlantic Forest). Other major terrestrial biomes that are encountered as we progress from the Poles to the Equator and from the center of a continent to the periphery, include the Tundra, Taiga (Boreal Conifer Forest), Temperate Desert Shrublands, Temperate to Tropical Grasslands and Savannas, Temperate Conifer Forests, Marshlands, Tropical Dry Forests, and Tropical Rainforests.

Although most field ecology research and education emphasizes terrestrial biomes, over 70% of the Earth is covered with ocean. Marine biomes are tremendously understudied, in part because there are fewer of them (as commonly defined, perhaps as a result of being less studied) and that they are logistically difficult to study. Nonetheless, many interesting ecological research questions are based there, and humans are increasingly relying on them for sustenance (already to the detriment of many marine fish populations). Physical features that structure marine ecosystems are mostly a consequence of the distance from shore and upwelling zones. Progressing from the shore to deep water, the major marine areas (biomes) include the Intertidal, Coral Reefs, Continental Shelf, Abyssal, and Pelagic.

A key feature of biomes is their structure, expressed not only in terms of dominant organisms but also by their biodiversity which varies considerably biome-to-biome. Causes in this variation in diversity are not always clear but may include such factors as primary productivity, latitude, altitude, and precipitation, among other abiotic factors.

### GPS

We will be navigating around these biomes using, the Global Position System (GPS). GPS allows you to find your way around the world and to accurately relocate a site. The accuracy of these measurements can be as high as within centimeters, a previously unattainable level.

A two step process attains high accuracy GPS readings. First, the GPS receiver obtains geographic information in the field from a subset of the satellites that are constantly orbiting the planet. These readings are stored in the receiver. Then, software supplied by the GPS company (in our case, Trimble’s Pathfinder system) uses the information obtained from the satellites and integrates it to triangulate a more accurate location. This secondary data analysis, called differential post-processing, will allow us to attain 1-3 meter accuracy using the Trimble GeoExplorer 3 GPS units.

GPS will be used during this class to determine the precise latitude and longitude of all field sites so that when we enter the data into the central repository (eBiome), we can georeference all data points. As a consequence, current and future data can be queried and analyzed spatially. Spatial analysis and the benefits posed by it are subjects that we will discuss and explore in greater depth during Module Two.