The variety of life on Earth exists as a myriad of microscopic and macroscopic forms. This biological diversity, or biodiversity, can be described at scales ranging from planetary, biome, or ecosystem to site-specific. Biodiversity includes genetic variation within species, the variety of species in an area, and the variety of habitats within a landscape. Roughly 1,750,000 species have been described and formally named, though estimates of the total biodiversity of life on Earth range from 5 to 30 million, with some estimates as high as 100,000,000 total species.
Most of terrestrial life reproduces, feeds, lives, and dies in the Critical Zone (see "Soil Biodiversity" [1] at Wikipedia for a brief introduction to soil biodiversity topics). Soil is intimately linked to biodiversity: soil provides the substrate through which much of the terrestrial biosphere interacts with the Critical Zone and its other component "spheres," and biota exert a significant influence on soil formation and Critical Zone processes. For example, plants absorb atmospheric carbon dioxide and store it in roots—eventually root respiration adds carbon dioxide to the soil atmosphere, changing, and at times controlling, weathering rates and other chemical processes within the soil and Critical Zone. A primary function of roots is to absorb water and nutrients, activity that directly influences the hydrosphere by drawing in soil moisture and dissolved constituents. This influences recharge rates and the chemistry of the soil and groundwater system. Roots also anchor plants within the Critical Zone and physically erode rocks by penetration and wedging, thus influencing interaction with the lithosphere.
But it is yet more complicated than that! Each species or organism may have a unique role in an ecosystem and therefore may interact with the Critical Zone in a different way. Furthermore, the interactions between organisms can be unique to species or unique to a specific habitat or ecosystem. Let's think about plants again. Cellulose, a potential source of energy, is tough and insoluble to most organisms. But termites (and grazing animals) contain microorganisms in their digestive tracts that convert cellulose to sugars usable by them and their hosts. Thriving termites in turn clear the landscape of dead plant litter, recycle contained nutrients back to the soil, and enhance soil porosity and permeability through construction of their subterranean chambers. An overall decrease in soil productivity and fertility has been observed in the absence of termites; thus, if not for those gut flora, a substantially different, and perhaps less fecund, ecosystem might exist.
Most cultures have recognized the importance of biodiversity for boosting overall ecosystem productivity and resilience to disasters. Yet continued destruction of habitat and species by human society is leading to what some biologists and paleontologists call the “Sixth Extinction,” perhaps the most rapid and destructive of extinctions in Earth history. Imagine total global human destructiveness perhaps exceeding the comet impact that occurred at the end of the Cretaceous [2] Period that finished off the dinosaurs!
In Lesson 10, we will consider the various means by which biologists and other natural scientists classify life on Earth. From there, we will launch into concepts of ecology, examining some of the interactions and processes between organisms and their environment—this examination will gradually focus in on the Critical Zone and soil processes that involve biota. We will complete Lesson 10 with an online forum to discuss the merits of placing a financial value on ecosystem processes. In Lesson 11, we will take a closer look at various expansive ecosystems of Earth and consider the relationship between them and the rest of the Critical Zone.
Learn about some interesting examples of the role of life in the Critical Zone.
In this lesson, we will examine basic ecological processes, eventually focusing through reading on links to the Critical Zone. This knowledge will prepare us for a closer examination of ecosystem-scale Critical Zone processes in Lesson 11 and our consideration of human interactions in the Critical Zone, in the manner of Earth system science, in our final lesson.
Lesson 10 will take us one week to complete. As you work your way through these online materials for Lesson 10, you will encounter additional reading assignments and hands-on exercises and activities. The chart below provides an overview of the requirements for Lesson 10. For assignment details, refer to the lesson page noted.
Please refer to the Calendar in Canvas for specific time frames and due dates.
ACTIVITY | LOCATION | SUBMITTED FOR GRADING? |
---|---|---|
Report on "Site-specific ecological processes" | pages 3, 5, & 6 | Submit to the "Lesson 10 - Ecological Processes" dropbox in Canvas |
"Merits of Valuing Ecosystem function" | page 7 | Post to the "Lesson 10 - Ecosystem Value" discussion forum in Canvas, then discuss |
If you have any questions, please post them to our Questions? discussion forum (not e-mail), located under the Discussions tab in Canvas. I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
Before we begin to explore the main topic of ecological processes in the Critical Zone, I want you to first study and consider biodiversity.
To learn more about the measurement, distribution, and control of the biodiversity of life on Earth, please visit and read:
Next, read the following article, located through Library Reserves:
Enjoy this reading. Learn that the upper reaches of the Critical Zone in an Ecuadoran forest canopy contains ~42,000 insect species per 2.5 acres. View and study the figure entitled "Life's rich tapestry" on pages 21–22. Note that the maintenance of biodiversity is attributed to a wide variety of microhabitats and environments in genetic studies of soil bacterial microdiversity, as the tropical-like variety of plant species in temperate South Africa is similarly maintained, whereas in dry central Australia the type and amount of vegetation dictate animal diversity.
As you reflect on what you just read, complete the following activity.
For this assignment, you will need to record your work on a word processing document. Your work must be submitted in Word (.doc) or PDF (.pdf) format so I can open it. In addition, documents must be double-spaced and typed in 12 point Times Roman font.
L10_ecologicalprocesses_AccessAccountID_LastName.doc (or .pdf). For example, student Elvis Aaron Presley's file would be named "L10_ecologicalprocesses _eap1_presley.doc"—this naming convention is important, as it will help me make sure I match each submission up with the right student!
The myriad variety of life is classified in a number of ways, dependent on scientific questions and need. Scientists utilize taxonomy to name and classify organisms, and they use systematics to create phylogenies—the evolutionary history of a species or group of species. Perhaps the most commonly known classification scheme utilizes evolutionary relatedness and a hierarchy of increasingly exclusive categories: domain, kingdom, phylum, class, order, family, genus, and species.
The following hyperlink provides a nice classroom Powerpoint slide show: Naming and Classifying Organisms [9].
Ecology, the study of the interactions between organisms and the environment, can be arranged into categories mostly based on increasingly generalized interactions between multiple organisms and their habitat. For example:
For this activity, I want you to continue working on the 3–4-page paper that you began on page 3 of this lesson.
For this assignment, you will need to record your work on a word processing document. Your work must be submitted in Word (.doc) or PDF (.pdf) format so I can open it. In addition, documents must be double-spaced and typed in 12 point Times Roman font.
The Earth's surface hosts a dynamic interplay of biotic and abiotic processes, all of which support the self-sustaining system that is the Critical Zone. The looming disaster associated with human activities and dominance of nature, however, threatens the balance of natural processes and challenges science to better understand the resilience of ecosystems and the CZ.
For this activity, I want you to complete the paper you have been working on for this lesson (see pages 3 and 5).
Upload your paper to the "Lesson 10 - Ecological Processes " dropbox in Canvas (see the Modules tab) by the due date indicated on our Canvas calendar.
You will be graded on the quality of your writing. You should not simply write responses to the questions and submit them to me. Instead plan on writing a short stand-alone paragraph (or page or whatever you decide is necessary considering any constraints I might have placed on you) so that anyone can read what you've written and understood it. You should strive to be specific and complete in responding to the questions. Your answers should be analytic, thoughtful and insightful, and should provide an insightful connection between ideas. The writing should be tight and crisp with varied sentence structure and a serious, professional tone.
Much of humanity tends to be oblivious to the role of nature in their lives. In North America, water comes from a faucet, food is gathered from stores, and toilets remove our waste. In less industrialized nations, much of the populace is too poor to concern themselves with natural ecological processes (though such processes may benefit their lives) as they deal more directly with poverty, hunger, and disease. But as the effect of humanity on nature has begun to deteriorate our lives and increase the need for engineering responses to our degradations, more scientists, planners, and citizens have begun to realize the value of a healthy, operational Critical Zone—various groups have gone as far as to estimate the financial value of such processes while others argue that such a move denigrates the natural world and attitudes toward it. You will read about this debate in the following activity.
Upon completion of the reading, you are to engage in a discussion of the readings with the rest of the class. The class discussion will take place during the week of this lesson in a discussion forum in Canvas titled "Lesson 10 - Ecosystem Value Discussion."
You will be graded on the quality of your participation. See the grading rubric [14] for specifics on how this assignment will be graded.
To learn more about valuing ecosystem services, read the original Costanza et al. paper published in the elite journal Nature:
Costanza, R., d'Arge, R., de Groot, R., Farber, S., Grasso, M., Hannon, B., et al. (1997).The value of the world's ecosystem services and natural capital [15]. Nature, 387(6630), 253–260. doi: 10.1038/387253a0.
You may also find this Nature Comment by Costanza and Kubiszewski [16] equally provocative and interesting.
Most of humanity forgets that pollinators and trees and the sun work for free, providing some of the many ecosystem services that benefit us. Listen to Paul Sutton, a geography professor at University of Denver who has calculated a dollar price of these services, explain how he made the calculations on this June 2014 edition of Living on Earth.
Nature's Dividend: ”Pricing Global Ecosystem Services"
Living on Earth [17]
To learn about the concept of Critical Zone services, read the paper by Field et al. (2015) [18].
This lesson briefly touched on the complexity of life on Earth and the interactions between organisms and their environment. It is important to recognize that the Critical Zone is so named because it is this thin veneer at Earth's surface that supports life on our planet—yet life also plays a complex and vital role in shaping and sustaining the zone. In the next lesson, we will study in more detail the complexities of various biomes and ecosystems and their role in CZ function. We will also evaluate the relationship between biomes and soils, and learn how to make site-specific determinations of landscape types.
You have finished Lesson 10. Double-check the list of requirements on the Lesson 10 Overview page to make sure you have completed all of the activities listed there before beginning the next lesson.
If you have anything you'd like to comment on or add to, the lesson materials, feel free to share your thoughts with Tim. For example, what did you have the most trouble with in this lesson? Was there anything useful here that you'd like to try in your own classroom?
Links
[1] http://en.wikipedia.org/wiki/Soil_biodiversity
[2] http://en.wikipedia.org/wiki/Cretaceous%E2%80%93Tertiary_extinction_event
[3] https://editors.eol.org/eoearth/wiki/Biodiversity_(main)
[4] https://www.tuhsd.org/
[5] http://en.wikibooks.org/wiki/General_Biology/Classification_of_Living_Things/Classification_and_Domains_of_Life
[6] http://www.diffen.com/difference/Autotroph_vs_Heterotroph
[7] http://en.wikipedia.org/wiki/Trophic_level
[8] http://soilweb200.landfood.ubc.ca/soil-biology/soil-organisms/
[9] http://krupp.wcc.hawaii.edu/BIOL200/powerpnt/pdffiles/classification.pdf
[10] https://www.e-education.psu.edu/earth530/sites/www.e-education.psu.edu.earth530/files/file/Campbell_ch52.pdf
[11] https://www.e-education.psu.edu/earth530/sites/www.e-education.psu.edu.earth530/files/file/readings/Bio_of_plants_cp29.pdf
[12] https://www.e-education.psu.edu/earth530/sites/www.e-education.psu.edu.earth530/files/file/Campbell_ch55.pdf
[13] https://78462f86-a-512471e5-s-sites.googlegroups.com/a/idakub.com/www/CV/publications/2014_Costanza_GlobalValueUpdate.pdf?attachauth=ANoY7cou1-4uiW7cINrfJeUffVtUQiqsYEkZB56AasPSIGzU1bz88fb7y9CV8Zs5LALppP62pbowvYRjAx1g5DKFkg4nNWf411u69cFlUo4EOG3jQIjWtjNthlQlnBKuMXHBDKU4A-Cjoon1iPdcGBp9oj1hj1pxs6aHbCe8hcL-fVjmwUON6DWH4JXeHTGebLV5LfX0ymLXX3cT89tYEyZ0mo6A6jrlXNA_n0n_yy1k3oBNdBo-CIUjhc8eMnGwOPdfaM5FLhVw&attredirects=0
[14] https://www.e-education.psu.edu/earth530/node/1650
[15] http://www.nature.com/nature/journal/v387/n6630/pdf/387253a0.pdf
[16] http://staging.community-wealth.org/sites/clone.community-wealth.org/files/downloads/article-costanza.pdf
[17] http://www.loe.org/shows/segments.html?programID=14-P13-00025&segmentID=4
[18] https://dl.sciencesocieties.org/publications/vzj/abstracts/14/1/vzj2014.10.0142