Forests are a major and diverse land cover occupying a third of the terrestrial vegetated surface; they store 50 to 65% of terrestrial organic carbon (including the soil) and contribute half to terrestrial productivity. Forest biomass stores close to 80% of all the biomass on Earth. As noted earlier, forests play an important role in the Earth system as carbon stocks, carbon sinks, mediator of the water cycle and as modifier of land surface roughness and albedo. Moreover, forests play a role as habitat for many species, are an economic source of timber and firewood and have recreational value for local populations and touristic visitors. Here, we appraise how ecosystem functions are influenced in particular by biomass and its vertical and horizontal distribution and hypothesize that almost all functions are directly or indirectly related to biomass, in addition to other factors. At landscape or regional scale, heterogeneity of biomass presumably has an important influence on a variety of processes, but there are gaps both in quantifying the heterogeneity of forests globally and in quantifying the effect of this heterogeneity. Similarly, while the role of forests for the global carbon cycle is important, large uncertainties exist regarding stocks, turnover times and the carbon sink function in forest, as an analysis of state-of-the-art carbon cycle and vegetation models shows. Upcoming global satellite missions such as GEDI, NISAR and BIOMASS will be able to address the above uncertainties and lack of understanding in combination with modeling approaches, in particular by exploiting information on vertical and horizontal heterogeneity.

中文翻译：

---

地球系统中森林生物量的各个方面：其作用和主要未知数

森林是一种主要而多样的土地覆盖物，占陆地植被表面的三分之一；它们储存了 50% 到 65% 的陆地有机碳（包括土壤），并对陆地生产力贡献了一半。森林生物量储存了地球上近 80% 的生物量。如前所述，森林在地球系统中发挥着重要作用，作为碳储量、碳汇、水循环的中介以及地表粗糙度和反照率的调节剂。此外，森林是许多物种的栖息地，是木材和木柴的经济来源，对当地居民和游客具有娱乐价值。这里，我们评估生态系统功能如何受到生物量及其垂直和水平分布的影响，并假设除其他因素外，几乎所有功能都与生物量直接或间接相关。在景观或区域尺度上，生物量的异质性可能对各种过程产生重要影响，但在量化全球森林的异质性和量化这种异质性的影响方面都存在差距。同样，虽然森林在全球碳循环中的作用很重要，但对最先进的碳循环和植被模型的分析表明，森林中的存量、周转时间和碳汇功能存在很大的不确定性。即将到来的全球卫星任务，如 GEDI，