Age structure and disturbance legacy of North American forests
Age structure and disturbance legacy of North American forests
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DOI：
10.5194/bg-8-715-2011
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发表时间：
2011-01-01
期刊：
影响因子：
4.9
通讯作者：
Deng, F.
中科院分区：
文献类型：
--
作者：
Pan, Y.;Chen, J. M.;Deng, F.
世界上大多数森林正在从过去的干扰中恢复。众所周知，森林干扰对森林生态系统的碳储量和碳通量有着深远的影响，但在森林碳收支估算中，对干扰影响的评估一直是一个巨大的挑战。森林在受到干扰后的二氧化碳净固存或损失遵循森林恢复的可预测模式。林龄与干扰以来的时间有关，是分析干扰对森林碳影响的一个有用的替代变量。在这项研究中，我们结合森林调查数据、历史火灾数据、光学卫星数据和NASA陆地卫星生态系统干扰自适应处理系统(LEDAPS)的数据集，编制了北美第一张大陆森林年龄图。为了量化不确定度，开发了年龄估计标准差的伴随图。我们通过分析几个世纪以来不同尺度的土地管理和自然干扰的原因，讨论了过去遗留下来的干扰的意义，以美国和加拿大不同地区的当前森林年龄结构为代表。我们还展示了如何将这些信息与库存数据一起用于分析碳管理机会。通过将有关林龄的地理信息与按森林类型估计的碳动态相结合，可以对森林的净二氧化碳吸收以及由于人为直接干预干扰/年龄状况而增加(或减少)这一速度的可能性进行简单而有力的分析。最后，为了提高碳循环模拟的空间精度，我们描述了如何将林龄数据用于大尺度碳模拟，包括基于陆地的生物地球化学模型和基于大气的反演模型。
Most forests of the world are recovering from a past disturbance. It is well known that forest disturbances profoundly affect carbon stocks and fluxes in forest ecosystems, yet it has been a great challenge to assess disturbance impacts in estimates of forest carbon budgets. Net sequestration or loss of CO2 by forests after disturbance follows a predictable pattern with forest recovery. Forest age, which is related to time since disturbance, is a useful surrogate variable for analyses of the impact of disturbance on forest carbon. In this study, we compiled the first continental forest age map of North America by combining forest inventory data, historical fire data, optical satellite data and the dataset from NASA's Landsat Ecosystem Disturbance Adaptive Processing System (LEDAPS) project. A companion map of the standard deviations for age estimates was developed for quantifying uncertainty. We discuss the significance of the disturbance legacy from the past, as represented by current forest age structure in different regions of the US and Canada, by analyzing the causes of disturbances from land management and nature over centuries and at various scales. We also show how such information can be used with inventory data for analyzing carbon management opportunities. By combining geographic information about forest age with estimated C dynamics by forest type, it is possible to conduct a simple but powerful analysis of the net CO2 uptake by forests, and the potential for increasing (or decreasing) this rate as a result of direct human intervention in the disturbance/age status. Finally, we describe how the forest age data can be used in large-scale carbon modeling, both for land-based biogeochemistry models and atmosphere-based inversion models, in order to improve the spatial accuracy of carbon cycle simulations.