三是六十年代“文革”时期，在“以粮为纲”的口号下，不少地方毁林开荒造地。
O O B-Time I-Time I-Time I-Time I-Time I-Time I-Time I-Time I-Time I-Time O O B-Abstract I-Abstract I-Abstract I-Abstract I-Abstract I-Abstract I-Abstract I-Abstract I-Abstract O O O O B-Location I-Location O B-Thing O B-Thing O B-Thing O