四级中心 meaning in Chinese

quaternary center

The author thinks that forest resource information management network system is an open system that has a hierarchical structure including many nodes that composed of four centers - national , provincial , city level and county level , its data processing and using is unified with discentralization and centralization
认为我国森林资源信息管理网络系统是一个由国家、省、地、县四级中心构成多点分布的层次结构，是一个分布式数据采集与存储、分布与集中相统一的数据处理和应用的开放式系统。