It tends to ignore, and thus eventually to eliminate, many elements in the land c

Ittendstoignore,andthuseventuallytoeliminate,manyelementsinthelandcommunitythatlackcommercialvalue,butthatareessentialtoitshealthyfunctioning。

Ittendstoignore,andthuseventuallytoeliminate,manyelementsinthelandcommunitythatlackcommercialvalue,butthatareessentialtoitshealthyfunctioning。
解析：句子主干“Ittendstoignoremanyelements”;两个that从句意思上转折，句法上为并列的定语从句，修饰thelandcommunity。注意插入语、定语从句以及代词指代的处理。
参考译文：这一体系容易忽视并最终消灭很多缺乏商业价值的物种，然而这些物种对于整个生物群落的健康运行是至关重要的。