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.
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。
Based on the demand analysis of the system, this paper raises the integral goals, the systematic holistic structure, functional model tree of the system.
本文在总结系统需求分析的基础上，提出系统的总体目标，系统的运行体系结构、系统总体结构、功能模型树。
The utility model provides an integral petroleum production tree, which is characterized in that a pipe cross and mutually connected main bars are a hollow and cuboid integral forging piece;
本实用新型提供一种整体式采油气树，其特征是四通和相互连接的主杆为一个空心长方体的整体锻压件；
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