Data from: Defining functional biomes and monitoring their change globally

Biomes are important constructs for organizing understanding of how the worlds’ major terrestrial ecosystems differ from one another and for monitoring change in these ecosystems. Yet existing biome schemes have been criticized for being overly subjective and for explicitly or implicitly invoking climate. We propose a new biome map and classification scheme that uses information on (i) an index of vegetation productivity, (ii) whether the minimum of vegetation activity is in the driest or coldest part of the year, and (iii) vegetation height. Although biomes produced on the basis of this classification show a strong spatial coherence, they show little congruence with existing biome classification schemes. Our biome map provides an alternative classification scheme for synthesizing data of the biogeochemical rates of terrestrial ecosystems. We use this new biome classification scheme to analyse the patterns of biome change observed over recent decades. Overall, 13 - 14% of analysed pixels shifted in biome state over the 30-year study period. A wide range of biome transitions were observed. For example, biomes with tall vegetation and seasonality associated with cold in the unfavourable growing period shifted to higher productivity biome states. Sites dominated by biomes characterized by short vegetation and low seasonality shifted to seasonally moisture-limited biome states. Our findings and method provide a new source of data for rigorously monitoring global vegetation change, analysing drivers of vegetation change and for benchmarking models of terrestrial ecosystem function.

生物群系（Biomes）是系统性认知全球主要陆地生态系统间差异、并监测此类生态系统变化的重要研究框架。然而现有生物群系分类方案因主观性过强，且明示或隐含地引入气候因子而饱受诟病。本研究提出一种全新的生物群系地图与分类方案，其构建依据三类信息：(i) 植被生产力指数；(ii) 植被活动最低值是否出现在一年中最干旱或最寒冷的时段；(iii) 植被高度。尽管基于该分类方案生成的生物群系具备极强的空间一致性，但其与现有生物群系分类方案的契合度极低。本研究生成的生物群系地图为整合陆地生态系统生物地球化学速率数据提供了一种替代性分类框架。我们借助这一全新的生物群系分类方案，对近数十年间观测到的生物群系变化模式展开分析。整体而言，在为期30年的研究周期内，13%至14%的被分析遥感像元发生了生物群系状态的转变。本次研究观测到了多种类型的生物群系转换事件：例如，以高大植被为特征、且在不利生长期呈现寒冷驱动季节动态的生物群系，转变为了生产力更高的生物群系状态；以低矮植被、低季节动态为特征的生物群系主导的区域，则转变为了受季节水分限制的生物群系状态。本研究的发现与方法，为严格监测全球植被变化、解析植被变化驱动因子，以及为陆地生态系统功能模型开展基准校验提供了全新的数据来源。