Historical forest baselines reveal potential for continued carbon sequestration

Abstract

One-third of net CO2 emissions to the atmosphere since 1850 are the result of land-use change, primarily from the clearing of forests for timber and agriculture, but quantifying these changes is complicated by the lack of historical data on both former ecosystem conditions and the extent and spatial configuration of subsequent land use. Using fine-resolution historical survey records, we reconstruct pre-EuroAmerican settlement (1850s) forest carbon in the state of Wisconsin, examine changes in carbon after logging and agricultural conversion, and assess the potential for future sequestration through forest recovery. Results suggest that total aboveground live forest carbon (AGC) fell from 434 TgC before settlement to 120 TgC at the peak of agricultural clearing in the 1930s and has since recovered to approximately 276 TgC. The spatial distribution of AGC, however, has shifted significantly. Former savanna ecosystems in the south now store more AGC because of fire suppression and forest ingrowth, despite the fact that most of the region remains in agriculture, whereas northern forests still store much less carbon than before settlement. Across the state, continued sequestration in existing forests has the potential to contribute an additional 69 TgC. Reforestation of agricultural lands, in particular, the formerly high C-density forests in the north-central region that are now agricultural lands less optimal than those in the south, could contribute 150 TgC. Restoring historical carbon stocks across the landscape will therefore require reassessing overall land-use choices, but a range of options can be ranked and considered under changing needs for ecosystem services.forest-agriculture trade-offs ͉ old-growth forest ͉ Eastern North America ͉ land-use history ͉ carbon sink

Evidence for a recent increase in forest growth

“…Calculating the amount of carbon stored in forests (37,38) guides predictions of how much potential carbon could move from storage (sinks) into the atmosphere (6). Just as deforestation constitutes an important cause of carbon leaving terrestrial stocks, regrowth of forests after land-use change has been recognized as critical to the removal of carbon from the atmosphere (39,40). This sequestration of carbon from the atmosphere into recovering forests can continue even for forests over 800 years old (41).…”

Loss of aboveground forest biomass and landscape biomass variability in Missouri, US

“…To determine historical biomass for Missouri forests during the period of the GLO survey (1813 to 1850), we used density estimates and diameter distributions for each ecological subsection and then modeled biomass, similarly to Rhemtulla et al (2009). For each ecological subsection, we developed parameters for probability distribution functions of tree diameters truncated at 13 cm using lognormal, negative exponential distributions, Weibull, and gamma distributions (Podlaski and Zasada, 2008; SAS Proc Severity, SAS software, version 9.1, Cary, North Carolina), similarly to Rhemtulla et al (2009).…”

“…For each ecological subsection, we developed parameters for probability distribution functions of tree diameters truncated at 13 cm using lognormal, negative exponential distributions, Weibull, and gamma distributions (Podlaski and Zasada, 2008; SAS Proc Severity, SAS software, version 9.1, Cary, North Carolina), similarly to Rhemtulla et al (2009). We then simulated 10,000 onehectare plots using random diameters generated from the parameters of the diameter distributions truncated at 13 cm and random densities generated from density estimates based on observations in the GLO survey (R Runuran; J. Leydold and W. Hö rmann, http://statmath.wu.ac.at/unuran, http://cran.rproject.…”

“…We used a conversion factor of 0.5 to convert biomass to carbon (the default; e.g. Rhemtulla et al, 2009). …”

公元733年河湟谷地耕地分布格局重建

“…、 美洲 [17][18][19] 、 非洲 [20] 内 某些区域土地利用/土地覆盖变化格局进行重建。 中 国 丰 富 的 历 史 文 献 资 料 为 研 究 历 史 时 期 LUCC 研究提供了大量的可用数据以及资料， 从重 建研究的空间范围来看， 主要从中国全国范围 [21] 、 中 国传统农业区 [22][23][24] 或某一个典型区域 [25][26][27] 三个空间 尺度对土地覆盖变化进行重建。从时间尺度上看， 汪桂生， 颉耀文等整理了黑河流域汉、 唐、 宋、 元、 明、 清代以及民国时期的耕地数据， 获得该区域时 间序列上较为完整的耕地资料 [27][28][29] ； 何凡能等将北 宋中期全国耕地面积进行整理及校正并重建出当 时的耕地格局 [30] ； 罗静等， 李士成等对青藏高原河谷 农业区的耕地格局重建工作， 分别集中在清代 [31] 和 近 100 年 [32] [42] 、 《南宋本大 唐六典校刊记》 [44] 、 《唐会要》 [45] 、 《北宋版通典》 [46] 、 《元 和郡县志》 [47] 、 《大唐六典》 [48] [31] ： …”