Since the beginning of the new century, of the five percent increase in the global green leaf area, one quarter has come from China.

网友说的应该是介词短语 of the five percent increase in the global green leaf area 吧。

这个词组，不是省略，也不是倒装，而是前置！

它原本作 one quarter 的定语，因太长，为照顾句子匀称被前置，短语后加了逗号停顿。我把它放在原来的地方（去掉逗号）：

Since the beginning of the new century, one quarter of the five percent increase in the global green leaf area has come from China.

【翻译】本世纪以来，全球5%的绿色植被面积增长中，有四分之一来自中国。