Complex sentence: The climax vegetation is called quebrachales, and consists of vast, low hardwood forests where various species of quebracho trees are dominant and economically important as sources of tannin and lumber.
Split into simpler sentences: The climax vegetation is called quebrachales, and consists of vast, low hardwood forests where various species of quebracho trees are dominant. The Quebracho tree is economically important as sources of tannin and lumber.