呼唤NN，prep2 7求指教

innerwarrior

So-called green taxes,which exact a price for the use of polluting or nonrenewable fuels, are havinga positive effect on the environment and natural resource base of countries as varied as China, the Netherlands,and Hungary.

base of countries是什么意思？base是动词？还是base是resource的名词，如果是the enviroment and natural resource base of countries.的话整句怎么理解呢？
对于as as，是不是前面是连词，后面是介词呀？