And 55 is a lot. On a per-area basis, Manhattan had more ecological communities per acre than Yosemite does, than Yellowstone, than Amboseli.
55种生态系统很庞大。在平均面积的角度上， 曼哈顿岛每英亩拥有的生态群落的数量 甚至比优山美地国家公园多， 也比美国黄石公园和肯尼亚安伯塞利保护公园多。