昆虫和病原体是森林生态系统的固有成分，通常其密度相对较低，所造成的损害较小，对树木生长及其活力的影响微乎其微。

Insects and pathogens are integral components of forest ecosystems and normally are present at a relatively low density, causing little damage, and having negligible impact on tree growth and vigour.

youdao

阐述了畜禽粪便中的主要污染成分氮、磷、恶臭、生物病原体、矿物质和药物添加剂对环境污染的危害。

The article expatiates the main pollutants including nitrogen, phosphor, odor, biological pathogenic agent, mineral matter, and additive agent of medicine from stockbreeding pollution.

youdao