trouble from VOA, wait for your answer

Hi, everybody! Glad to have yours attention.

I'm from China, named Wang Linhai. I have some trouble understnading these two sentences as I listen to VOA.

 a windbreak is best if it has only sixty to eighty percent of the trees and plants needed to make a solid line.  An easy rule to remember is that windbreaks can protect areas up to ten times the height of the tallest trees in the windbreak

Question one: how to understand "a solid line",what do people use it for? how to understand this sentence?what doese it mean?

Question two: "protect areas up to ten times" and " the height of the tallest trees in the windbreak," how do they combine to be a sentence,what does it mean?

thanks so much, waiting for your answer.

 A "windbreak" is almost the opposite of a "firebreak".  A windbreak or a shelterbelt is a growth of trees in several rows that offers shelter to houses or farmland from strong gusts of wind. If the tallest trees are averaging about 5 meters, then distance of land protected leeward (opposite to the direction of the wind) will be about 50 (5 X 10) meters.

 “a windbreak is best if it has only 60 to 80 percent of the trees and plants needed to make a solid line” I think this part of the broadcast explains it: “However, windbreaks seem to work best when they allow a little wind to pass through. If the wall of trees and plants stops wind completely, then violent air motions will take place close to the ground. These motions cause the soil to lift up into the air where it will be blown away.” The “solid line” would be breadth of the plantation where the trees are adequately spaced out, instead of being planted one against the other.

 For some of our other English learners: Well, we sort of understand the word “windbreak”. Please don’t confuse it with the phrase “break wind”; I’ll let thefreedictionary explain this, “to allow gas to escape from your bottom, especially loudly”.

http://bbs.netat.net/archiver/?tid-26859.html

http://www.voanews.com/specialenglish/2008-01-20-voa1.cfm

Hello, sir!

thanks so much . you have been a great help.

Now I understand those two sentences. thanks a lot.

by the way, I like the worlds"stary by doing what's necessary, then what's the possible, suddenly, you are doing the impossible" from your space. it's so cool.

And I also amused at your "break wind", too fun.

You are welcome.

I see that you speak Spanish – that's a beautiful language. I started on it, but I gave up as there was no one to practise the language with me. Well, there are lots of people at Ebaby from Spain and the Latin American countries who would probably be happy to communicaete in English and Spanish.