请看例句：
Since April, several national scenic areas have issued sightseeing bans in order to better protect their fragile ecological environments.
4月以来，多个国家级风景区发布禁游令，以更好地保护该地区脆弱的生态环境。

可可西里、昆仑山、三江源、柴达木盆地、青海湖、年保玉则等自然景观(natural attractions)资源珍贵而稀缺。每年夏天，青海高原对中外游客来说都是热门的旅游目的地(a popular sightseeing destination for tourists from home and aboard)。但数量日益增多的游客(the ever-growing number of visitors)正给景区的生态环境带来越来越大的压力(put increasing pressure on the scenic areas' ecosystems)。

今年4月，青海湖景区保护利用管理局发布通告，青海湖景区(Qinghai Lake Scenic Area)暂时关闭二郎剑和鸟岛等景区(temporarily close areas such as Erlangjian and Bird Island)。当月，青海还发布通告，年保玉则国家公园无限期关闭(Nianbaoyuze National Park closed indefinitely)。5月24日以来，三江源国家公园发布黄河源头(the Yellow River source region)景区禁游令(sightseeing bans of scenic areas)，禁止一切单位和个人进入扎陵湖、鄂陵湖等源头保护地观光或开展探险活动(all the institutions and individuals are prohibited from entering the source region, including Zhaling Lake and Eling Lake for sightseeing or expeditions)，禁游面积(the forbidden area)达1.91万平方公里。

上述发布禁游令的旅游景区均地处青海高原生态系统极为敏感的区域(be all located in the regions with extremely sensitive ecological environments)。禁游令是保护生态环境和自然资源，维护青藏高原生物多样(maintenance of biodiversity in the Qinghai-Tibet Plateau)，保障珍稀物种栖息地(protect the habitat of rare species)不受威胁的必然之举，是保护重于开发(protection takes precedence over development)的郑重宣示。

[相关词汇]
生态健康 ecological health
绿色发展 green development
固体废物污染 solid waste pollution
生态保护红线 red lines for ecological protection