你好!
"省级自然保护区" 翻译为"The Provincial Nature Reserve" 是正确的.更加正式的译法可以是" The Nature Reserve of Provincial Level".
这段话的建议翻译是：“Being the largest Provincial Nature Reservation Area of Pearl River Delta in Guangdong, the Mount XX has been highly valued by UNESCO, and taken as the key reserch subject of the internationalized Plan "Man and Biosphere"(MAB). "
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