In Temperate
Grasslands, there is high evaporation and not sufficient rainfall?
High Evaporation
leads to High rain fall like in equator and therefore equatorial rain forest.
Then how is is not the same in temperate grasslands?
The concept of vegetation, rainfall etc. need to be
understood carefully. One of the complex portions of geography!!
Firstly, what decides the height of the tree? Or its
thickness?? In short, why huge trees don’t come up at all places?
The growth depends on the nutrition the plant gets. So it’s:
nutrition, water, sunlight!
Water is present in the atmosphere is of no use! It needs
that water at the soil, what is called as 'soil moisture'. Soil moisture
depends on the balance between input water and output water!
Now, when you have a soil rich with nutrients, lots of
moisture and good sunlight, the plant grows big!!
Say the depth from top soil to 10 meters may be relevant to
the trees as the roots go that deep only! Right? In this section of soil, if
you have moisture, then tree is happy to grow!!
What is the water balance there?
Input water is rain.
Output is: evaporation and also seepage down!!
So if you have very loose soil, like sand, then water percolates
down and not available to tree roots!!! Same manner, if sun shines closer, it evaporates
all water!!!
Whatever evaporates from one place, need not fall in same
place as rain!! Monsoon rain picks up its water from Arabian Sea!!!
So, for that particular area, the evaporation is high, but,
rainfall is RELATIVELY not high to compensate!!! So, the net effect is: more
moisture vaporizes, than it’s compensated by rain!!! So, the soil moisture is
not enough to support growth of huge vegetation like trees!!!
P.S
Geography, in one way is not a basic science. Indeed you
need to be good in science, to understand geography!!! The geography books
don't explain the basic science involved in detail!!
In geography, we have a word for what decides vegetation - Potential evapotranspiration
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