改變不可逆轉
An ecosystem describes a certain area where all of the living and nonliving things interact with each other, such as the plants, animals, and weather.
生態系統是指在某種環境中，動植物與氣候、生物與非生物之間的相互作用。
interact with=跟…互動
Ecosystems are constantly going through small changes, but there is usually an overall balance that is maintained.
生態系統經常出現小改變，但整體而言仍維持其平衡狀態。
maintain(v.)維持;保持
If this balance is broken, it could mean disaster for those living in the ecosystem.
若這種平衡被打破，對該生態系統中的物種而言將是場災難。
disaster(n.)災難
In a balanced ecosystem, the number of each species is stable and does not change dramatically.
在平衡的生態系統中，物種的數量穩定且不會大幅改變。
stable(adj.)穩定的
However, if a new species is introduced, or there is a disease that causes the sudden death of some species, then the balance of the ecosystem will shift completely.
然而，若有新物種被引入或是出現致死的疾病，那生態系統的平衡將徹底改變。
introduce(v.)引入;引進disease(n.)疾病shift(v.)更動;改變
When brown tree snakes were accidentally introduced into Guam in the 1950s, they quickly multiplied because there were no predators that hunted them.
人類在1950年代無意中將棕樹蛇引入關島，由於棕樹蛇在當地沒有天敵，因為數量大增。
multiply(v.)大幅增加predator(n.)捕食性動物
As a result, they are responsible for the extinction of nine out of 11 of the island’s forest birds.
結果棕樹蛇造成關島的原生鳥類瀕臨滅絕，島上11種鳥類中已有九種因此絕跡。
be responsible for=某事的成因extinction(n.)絕種;滅絕
Ecosystems can easily bounce back from minor events, but major events will likely cause irreversible changes to the natural balance, leading to the extinction of some species.
生態系統可在輕微變動後恢復，但情形嚴重的話可能會對自然界的平衡帶來不可逆轉的改變，導致某些動物絕種。
bounce back from=從~恢復過來irreversible(adj.)不可逆轉的