Global Homogeneous Response Units

The concept of homogenous response units (HRU) was designed as a general concept for the delineation of basic spatial units. Only those characteristics of landscape, which are relatively stable over time (even under climate change) and largely unsusceptible to anthropogenic influence, were selected. The HRU can be seen as a basic spatial framework for the implementation of climate change and land management alternative scenarios into global modeling and therefore is a basic input for delineation of landscape units. HRUs are defined based on classifications of altitude (five classes: 1 (0 - 300m), 2 (300 - 600m), 3 (600 - 1100m), 4 (1100 - 2500m), 5 (> 2500m)), slope (seven classes(degrees): 1 (0 - 3), 2 (3 - 6), 3 (6 - 10), 4 (10 - 15), 5 (15 - 30), 6 (30 - 50), 7 (> 50)) and soil composition (five classes: 1 (sandy), 2 (loamy), 3 (clay), 4 (stony), 5 (peat)). e.g. HRU111 refers to Altitude class 1: 0-300m; Slope class 1: 0-3 degrees; and Soil class 1: sandy. Areas of non-soil are assigned 88. HRUs have a spatial resolution of approximately 10 km**2.

同质性响应单元（homogenous response units，HRU）的概念是为划定基础空间单元而提出的通用概念。仅选取那些随时间推移相对稳定（即便在气候变化情境下亦如此）且基本不受人为活动干扰的景观特征。HRU可作为将气候变化与土地管理备选情景纳入全球建模的基础空间框架，因此是景观单元划定的基础输入项。HRU的定义基于海拔、坡度与土壤组成三类要素的分级分类：其中海拔分为5级：1级(0-300米)、2级(300-600米)、3级(600-1100米)、4级(1100-2500米)、5级(>2500米)；坡度分为7级（单位为度）：1级(0-3°)、2级(3-6°)、3级(6-10°)、4级(10-15°)、5级(15-30°)、6级(30-50°)、7级(>50°)；土壤组成分为5级：1级(砂质)、2级(壤质)、3级(黏质)、4级(石质)、5级(泥炭质)。例如，HRU111代表海拔等级1（0-300米）、坡度等级1（0-3°）且土壤类型为等级1（砂质）的单元。无土壤区域被赋值为88。HRU的空间分辨率约为10平方千米。