The idea of regional green belts in the Ruhr region (Germany) dates back to 1912, but only 60 years ago, the term regional green belt appeared in official German spatial planning, and ever since, regional green belts as a theoretical concept and a planning category form an integral part of regional planning in the area. This paper tracks back the changing concepts, functions of the regional green belts, it analyzes their present state and proposed future. From the starting point of their formal existence in the Regional Development Plan as of 1966, the original regional green belts (RGBs) significantly lost open space and consequently areas providing ecosystem services diminished. Parts of RGBs were transformed into settlement and areas for traffic and technical infrastructure, whereby the loss is spatially unevenly distributed. New delineations of the regional green belts are currently under discussion for the forthcoming regional plan. The green belts would be substantially enlarged from formerly 281 km2 (1966), over 696 km2 (2004) to 1103 km2 by extending them into the less densely populated outer zones. In the crucial central parts of the Ruhr region, where the original RGBs are located, an ‘adaptive’ reduction will take place as a sacrifice to the already happened change to urban, non-open space land cover. Open spaces will be attached to the original RGBs and form green circles surrounding the cities of the Ruhr region’s core area. We assess the potential ecosystem services provision of the 23 parts of the proposed new regional green belts based on the present land cover. We criticize the planning category regional green belt as indistinct and inappropriate to express the requirements of optimal protection of areas providing ecosystem services. Regional green belts need to be better backed-up by overarching legally binding planning of built-up areas and open space.

中文翻译：

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鲁尔区的区域绿化带。重新审视生态系统服务的规划概念

鲁尔区（德国）区域绿化带的概念可以追溯到 1912 年，但仅仅在 60 年前，区域绿化带一词出现在德国官方空间规划中，此后，区域绿化带作为一个理论概念和规划类别构成该地区区域规划的一个组成部分。本文追溯了区域绿化带的概念、功能变化，分析了它们的现状和展望。从 1966 年在区域发展计划中正式存在开始，原始区域绿化带 (RGB) 显着失去了开放空间，因此提供生态系统服务的区域减少。部分 RGB 被改造成居民点和交通和技术基础设施区域，因此损失在空间上分布不均。目前正在为即将出台的区域计划讨论区域绿化带的新划定。通过将绿化带延伸到人口密度较低的外围区域，绿化带将从之前的 281 平方公里（1966 年）、超过 696 平方公里（2004 年）大幅扩大到 1103 平方公里。在原始 RGB 所在的鲁尔地区的关键中心部分，将发生“适应性”减少，以牺牲已经发生的城市非开放空间土地覆盖变化。开放空间将连接到原始的 RGB 并在鲁尔区核心区的城市周围形成绿色圆圈。我们根据目前的土地覆盖情况评估拟建的新区域绿化带的 23 个部分的潜在生态系统服务供应。我们批评规划类别区域绿化带模糊和不恰当地表达对提供生态系统服务的区域进行优化保护的要求。需要通过对建成区和开放空间进行具有法律约束力的总体规划来更好地支持区域绿化带。