Posted by: chrismaser | February 29, 2012

WHAT—EXACTLY—IS BIODIVERSITY?

As species evolved throughout the slow reaches of time, they diversified in form, function, and their genetic adaptability to changing conditions. “Function,” in this sense, means how an individual organism behaves within a given species, how a species as a whole behaves, as well as the ever-present interactions of various species with one another in self-reinforcing feedback loops in space through time to denote the variety of life in all its myriad relationships—to which we humans affix the term “biodiversity.”

Diversity is not only the quality of being different but also the richness of the world and our experience of it. “Biophysical” diversity, as opposed to “biological” diversity (= biodiversity), encompasses the world’s ultimate variety of nonliving and livings forms, each a dynamic, interactive component in a suite of relationships that fit precisely into other relationships that fit into yet other relationships, ad infinitum—all of which are constantly changing, constantly becoming something else.

THE WONDER OF LIFE

The most wonderful diversity of all lies in spark of life. Just imagine—since that first living cell, nothing has ever again been alone on Earth because, since that first living cell, the diversity of life has literally filled the seas and covered the planet. How exactly that part of creation called “life” began is a question as old as the first hominid to ponder it.

Nevertheless, the first animated cell not only began life and living diversity but also a whole dimension of diversity beyond our present comprehension—infinite diversity created out of nonliving, physical substances and out of living, biological organism, which coalesce into the biophysical diversity of the living with the nonliving in various relationships in space and time. Think, for example, of the vast array of marine snails, each of which makes its own peculiar shell out of nonliving materials. Without calcium carbonate, not a single the snail’s shell could exist. Without the variety of living snails, the variety of shells could not exist because each snail is the artist of its own shell—both within a species and among species. Therefore, no two snail shells have ever been exactly the same, despite the innumerable individuals that have graced the long corridors of time.

The wonder of biodiversity is the wonder of its having begun with a single living cell, or maybe even a handful of cells scattered throughout the ancient sea of the world. From that cell, or perhaps those cells, arose the longest known living experiment on Earth—the genetic experiment of life. You could argue that combinations of genetic materials are really no different from the original combinations of chemicals that gave rise to chemical compounds. If you omit the spark of life from this equation, you would be right. But that indefinable spark of life is there—and that changes everything. Moreover, the experiment continues.

When, for example, the sprout of a wild radish becomes breakfast for a caterpillar early in its growing season, the insect’s munching induces the radish to produce chemical defenses against another attack. As the munched plant grows, other insects in the area may chew on it also, but do far less damage than they do to plants that have not been previously nibbled. Thus, by the end of the growing season, the plant munched on early in the season not only suffers less damage from subsequent samplings by insects but also produces more seeds than do radish plants that escaped early damage.

Therefore, as I meet each living thing that shares this magnificent planet with me, I see the pinnacle—the culmination—of billions upon billions upon billions of genetic experiments, all of which have taken place over millions of years, all embodied in each butterfly, each rose, each tree, each bird, and each human being. Every individual living thing on Earth is the apex of creation, because every living thing is the result of an unbroken chain of genetic experiments (each individual that ever lived being part of a single experiment) that began with the original—the very first—living cell that ultimately filled worldwide seas with life.

Just think—no to living things in all of time have ever been exactly the same. In fact, no two things in the universe have ever been, or ever will be, exactly the same. Such is diversity.

HOW DIVERSITY COMPOUNDS ITSELF

Diversity as a dimension of itself may seem like an odd idea. But consider that all the various dimensions of diversity ultimately come together to create diversity in the form of a seascape, a landscape, the Earth, a moonscape, the moon, or even the Universe as a whole—and our individual perceptions of them. Thus, when we alter one thing, we alter everything. That cumulative alteration is the ongoing principle of creation. To see how this principle works, how diversity continually creates itself, we will examine the history of a landscape in the southern Appalachian Mountains at a place where the states of Tennessee, North Carolina, and Georgia converge.

It has been 260 million years since the Appalachian Mountains were last affected by significant upward thrusting of the Earth’s crust. At mid and high elevations, during the last period in which the glaciers of the Pleistocene Epoch reached their maximum development, about 20,000 years ago, the ground surrounding the glaciers was permanently frozen, termed “permafrost.” In addition, the potential area of alpine tundra extended from an elevation of about 5,000 feet to the summits of the highest mountains. (Tundra is a treeless area that has permanently frozen subsoil and supports such low-growing vegetation as lichens, mosses, and stunted shrubs. Tundra that occurs above the tree line in elevation on high mountains is termed “alpine tundra,” as opposed to “arctic tundra,” which occurs above the tree line in northern latitude.)

During this time, sediments in all sizes, ranging from boulders to clay and silt, surrounding the glaciers and beneath them were frozen in place. With the warming of the climate about 15,000 years ago, the frequency and the intensity of the cycles of freezing and thawing increased. Finally, the climate warmed sufficiently so that the once frozen materials began to move downslope with the pull of gravity, in what is known as “soil creep.”

With the onset of recent times, about 10,000 years ago, the climate warmed again. This change resulted in the sediments, such as boulders, pebbles, or clay, washing downslope through the force of water, as opposed to being embedded in glaciers moving downslope by the pull of gravity, as in colder times.

From the time when the last glacial period was at its height to the present, the major factor in forcing the landscape to change was shifts in climate. Freezing and other ice-related phenomena were the main causes of disturbance in the biophysical system. The combination of cold temperatures and cycles of freezing and thawing, which churned the soil, resulted in a landscape mosaic of permanent snowfields and alpine tundra above 5,000 feet elevation, while there was a species-rich boreal forest below 1,600 feet. Boreal forest means “northern forest,” which today is characterized by the vast, short forest of small trees that occurs across central and northern Canada and throughout interior Alaska.

As the climate warmed, herbaceous species of plants that formerly grew in alpine tundra either died out or were restricted to high-elevation sites kept open by such disturbances as fire, falling rocks, and landslides. In addition, the boreal forest had spread upslope to the summits of the highest mountain peaks, and a deciduous forest had replaced it at mid and low elevations. The forest communities as we know them today have evolved only recently, some within the lifetimes of the oldest living trees.1

So, the diverse elements of diversity itself, both physical and biological, such as the scales of time, space, temperature, and the processes that shape the Earth, as well as the Earth’s living organisms, all coordinated by climate, have molded and remolded the landscape into an ever-changing kaleidoscope of mosaics—each mosaic an interlude, a snapshot in the ever-changing parade of living organisms we call “biodiversity.”


 


 

Series on Biodiversity:

• Earth Before Oxygen

• The Advent of Oxygen

• The Long, Slow Path To Life As We Know It

• From Whence Comes Today’s Biodiversity?

• Biodiversity—Our Social-Environmental Insurance Policy

• Endangering Our Environmental Insurance Policy

• A Lesson of Consciousness From the California Condor

Related Posts:

• Biodiversity–The Variety Of Life

1. Composition, Structure, And Function

2. Disturbance Regimes

3. Cumulative Effects, Lag Periods, And Thresholds

4. Biological Diversity

5. Genetic Diversity

6. Functional Diversity

7. Nature’s Services–Ecological Wealth Across Generations

• Principle 1: Everything is a relationship

 


ENDNOTES

1. The following discussion of the southern Appalachian Mountains is based on: (1) Hazel R. Delcourt, and Paul A. Delcourt. Quaternary Landscape Ecology: Relevant Scales in Space and Time. Landscape Ecology 2 (1988):23–44, and (2) Paul A. Delcourt and Hazel R. Delcourt. 1958. Dynamic Landscapes of East Tennessee: An Integration of Paleoecology, Geomorphology, and Archaeology. University of Tennessee, Knoxville. Department of Geological Science, Studies in Geology 9: (1958):191–220.


Text and photos © by Chris Maser 2012. All rights reserved.

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