In previous decades pollution, soil depletion, the destruction of the ozone layer and an imminent ice age were the ecological catastrophes that faced us.
经过过去几十年的污染，土壤贫化、臭氧层破坏和即将到来的冰川时代是我们要面临的生态灾难。
2
The main factors affecting on the community structure and dynamics of the pests were the biological characters of pests, age of lichee tree, climates and ecological circumstance of the orchard.