Friday, March 15, 2013

What made us the way we are?

Did you ever wonder what the land your home is built on today was like 500 years ago ago during the time that Native Americans lived here? What kinds of vegetation existed?  What ecosystem of animals would live there?  There are few vestiges of “native land”  left in the San Francisco Bay area... Judging from tree ring evidence we can see that growth has been more or less constant for a very long time – a strong indication that temperature and moisture patterns have not varied greatly...  ( Some of the Sequoia trees show records of growth for well over 3000 years. ) 
Whittaker Biome Diagram

One of the startling scientific discoveries of this century is that climate patterns are amazingly consistent throughout the world.  If you know the annual temperature and moisture for a location, you can make a solid prediction about what the vegetation pattern will be.  All places on earth with an average annual temperature of 15C  (59F) and 200 cm (78  inches) of rain will have natural deciduous forests ( these are the trees that lose their leaves in the fall – Oaks, maples, walnuts etc. ).  Of course if humans have come along and cut all the trees down – then it may be farm land... but if the farms disappeared and the land was left to redevelop naturally – the deciduous forests would return.  While vegetation may be similar, it may be different species all well adapted to that climate zone. - Example: Cactuses have evolved in the Americas and Euphorbias are found in similar climates and look much like cactus - and they are found in Africa.

Limited water but frozen solid most of the year.
Such combinations produce Alpine and Tundra biomes.

In Fremont, where I live, the average rainfall is 38cm ( 14.85 inches) and  a year around average temperature is 15C ( 60F ) .  That means that our native plant population would evolve into a  pattern between grassland/desert and woodland... this would produce a scrub growth of coyote bush and other chaparrals plant growth.  Oakland, right on the bay and directly in line for prevailing Pacific storms, receives enough extra rain to "be a land of live oak trees... a temperate deciduous forest.  ( Which existed there before they were all cut down ). This year Fremont has received only 9 inches (23 cm.) if that period continued for a number of years we would evolve into a biome close to a desert...

Fremont Hills - Native scrub growth - Chaparral growing on our local hills

Of course the basic pattern may be modified or even dependent on such things as the regular occurrence of lightning fires or fires set by the native people, the timing of rain fall within the year, the angle of the sun in the sky...but all of these would produce relatively minor changes in the over-all pattern.

So the grasslands of the Pampas in Argentina, the South African Veldt, the Great planes of North America, the grasslands of Mongolia, the vast Hungarian Puszta grasslands, ... all of these have very similar patters of temperature and precipitation.

Taiga forest - low mountains adjacent to Pacific ocean

The conifer forests in Austria, Himalayas, Sierra Nevada, locations in Australia, the vast forests in Canada and Siberia... all fit the pattern of Taiga.

The fog zone along the Pacific coast: Thick taiga with mixed surface plants - temperate rain forest

Culturally during the great migrations into the Americas during the 19th and 20th century, European and Asian settlers tended to move to locations with a similar climate pattern to the one they left behind.  My grandparents from Central Bohemia felt right at home in the wheat lands of Kansas.

Is this Bohemia or Kansas?  Grasslands with wooded creek bottoms

All of this brings to mind the significant difference in Climate and Weather – daily patterns may be important to our affairs – but the kind of climate patterns we are talking about here are maintained consistent for large blocks of time.  There have been sudden periods of substantial climate change in the history of our earth – many of them can be related to unusual periods of volcanic activity that altered the composition of the atmosphere,or  meteorite or comet impacts on earth that also altered the atmosphere.  Some of these periods caused vast die offs of large groups of organisms.

Nevada desert  - enough water to support a variety of plants

What we face today is a "sudden" (since the start of the industrial revolution) release of carbon gases into the atmosphere due to human activity – We have all seen the tankers of oil, the ship loads of crude oil, the trains made up of hundreds of cars filled with coal, pipelines transporting natural gas... all of there carbon compounds to be burned and their gases released into our atmosphered... and this has been going on now for over 200 years (with the rate accelerating).  Our great earth has the ability to absorb many insults... but the carbon gases being released are changing our atmosphere and our weather pattern.

Some grasslands like this attempt to revert to forest - the ranchers must constantly "weed out" cedars attempting to grow in, and revert to forest.

When the average temperature of the earth is changed by even a small amount per year... it causes weather patterns to alter.   Changing climate patterns also cause change in the location and intensity of storms, precipitation, and ice packs.    Some places that were once grasslands would morph into deserts.  A woodland area may change into scrub growth, a temperate rain forest may become able to sustain tropical rain forest vegetation.  The major wheat producing areas may be moved further north into Canada and Siberia (but that depends on the rain they receive.)

The land of minimal water ( and high mineral soil) true desert

Take care of your Mother Earth...She has been good to you...


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