但是随着全球变暖向高海拔地区蔓延，一个不受欢迎的居民进入了这个脆弱的生态环境：山地松树甲虫。
But as global warming snakes its way into higher altitudes, a less-welcome resident in taking up space in this fragile ecosystem: the mountain pine beetle.
降雨模式的改变威胁着该地区脆弱的生态系统。
Changing rainfall patterns threaten this region’s fragileecosystem.
西部地区是我国生态旅游资源最丰富的地区，同时也是生态系统极其脆弱的地区。
The western region owns the richest eco-tourism resources of China, however, the ecosystem there is extremely frail as well.
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