This paper estimates the global biotic carbon fluxes into the atmosphere under various scenarios of changes in forest area for temperate/boreal and tropical zones. Forestry scenarios have been developed from both national forest land-cover inventories and various estimates for tree vegetation-cover areas derived from the Earth’s remote sensing data for recent decades. Three scenarios have been proposed for changes in the area of temperate/boreal forests: FAOSTAT (a growth scenario on the basis of inventories), CONST (a scenario of maintaining the present level), and LANDSAT (a scenario on the basis of satellite data from different sources). The trend of tropical deforestation is maintained for FAOSTAT and LANDSAT scenarios. Together with GEPL97 (the base scenario published earlier by the authors), these scenarios have been used to obtain model biotic carbon fluxes. A model of the global carbon cycle developed in MPEI and recently updated to take into account anthropogenic carbon emissions (both industrial and related to deforestation/land use) has been used to perform a thorough analysis of the plausible dynamics of biotic carbon sources and sinks. It has been shown that the magnitude and sign of biotic carbon fluxes into the atmosphere depends substantially on the adopted scenario—from preserving the biosphere as an effective sink of excess carbon from the atmosphere in the current century (GEPL97 and CONST) to its turning into an additional source of CO2 (LANDSAT). The FAOSTAT scenario leads to the return of biotic carbon fluxes by 2100 to the modern level. The maximum difference in net carbon fluxes from the biosphere to atmosphere for the scenarios considered here is almost 2.5 Gt C/year and falls approximately on the middle of the current century. The difference between the corresponding CO2 concentrations for these scenarios reaches 65 ppm by 2100.

中文翻译：

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不同森林面积变化情景下生物碳通量的动态变化

本文估计了在温带/北方和热带地区森林面积变化的各种情景下，全球生物碳通量进入大气。近几十年来，林业情景是根据国家森林土地覆盖清单和根据地球遥感数据得出的各种树木植被覆盖面积估算得出的。针对温带/北方森林面积的变化提出了三种情景：FAOSTAT（基于库存的增长情景）、CONST（保持当前水平的情景）和 LANDSAT（基于卫星数据的情景）来自不同的来源）。在 FAOSTAT 和 LANDSAT 情景中保持热带森林砍伐的趋势。连同 GEPL97（作者早先发布的基本场景），这些情景已被用于获得模型生物碳通量。MPEI 开发并最近更新以考虑人为碳排放（工业和与森林砍伐/土地利用相关的）的全球碳循环模型已被用于对生物碳源和汇的合理动态进行彻底分析。已经表明，进入大气的生物碳通量的大小和符号在很大程度上取决于所采用的情景——从在本世纪（GEPL97 和 CONST）保护生物圈作为大气中过量碳的有效汇到其转变为一个额外的 CO2 来源 (LANDSAT)。FAOSTAT 情景导致到 2100 年生物碳通量恢复到现代水平。对于此处考虑的情景，从生物圈到大气的净碳通量的最大差异几乎为 2.5 Gt C/年，大约在本世纪中叶下降。到 2100 年，这些情景对应的 CO2 浓度之间的差异将达到 65 ppm。