重庆市退耕还林工程林固碳潜力估算

为估算重庆市退耕还林工程林固碳潜力,调查收集重庆市2000～2007年退耕还林工程逐年造林的树种、面积等数据资料,利用国家森林资源清查资料中该市人工林生长历史数据模拟人工林生长曲线,借助该曲线并结合经调研国内外文献所得林分树种的生物质密度、碳含量、生物量开展系数等生物物理参数,设计林分碳储量变化计算模型.结果表明,重庆市退耕还林工程林的稳定碳积累量在2010、2020、2030、2040及2050年分别为14.276～14.740、33.463～41.059、43.796～57.915、50.254～70.124和54.024～77.655Tg(T=1012);退耕还林工程林未来40年内具有显著碳汇功能,其年碳汇量在未来5年左右将达到高峰,2005～2020年是退耕还林工程林年碳汇能力的强盛期.     

西藏自治区退耕还林工程林碳汇潜力研究

根据西藏自治区2002—2010年退耕还林工程逐年造林的树种、面积数据,利用国家森林资源连续清查中人工林生长的历史数据拟合造林树种生长曲线,结合经文献调研所获得的树种生物量扩展系数、木材密度和碳含量等参数,采用"人工林生长曲线法"估算出西藏未来50年退耕还林工程林的碳汇潜力。结果表明:在2020,2030,2040,2050,2060年,西藏的退耕还林工程林碳汇在无采伐模式下分别为0.214,0.205,0.159,0.087,0.054 TgC/a;在采伐模式下分别为0.214,-0.205,0.171,0.243,-0.352 TgC/a。     

四川省退耕还林碳汇潜力预测研究

通过调研四川省退耕还林工程实施现状，建立模型，预测未来60 a 四川省退耕还林工程的碳汇潜力。采用经由森林清查人工林历史生长数据拟合的里查德方程（Richards equation）进行分树种生长量预测，依据文献调研所得有关参数计算相应的生物碳储量，结合碳排放、碳基线和碳泄漏的分析与估算，得出四川省退耕还林工程未来60 a碳汇量。     

云南退耕还林工程林木生物质碳汇潜力

收集云南省2000--2006年各类退耕还林面积和树种数据,设定2007--2010年间的6种年度造林与采伐情景,根据云南省森林资源清查中的人工林生长数据,拟合出各造林树种的经验生长曲线,并利用这些能够反映不同气候和立地条件下人工林的平均生长曲线,结合生物量扩展因子、木材密度和碳含量等参数,估算不同情景下的林木生物质碳贮量及其变化.结果表明:云南省退耕还林工程林木生物质碳贮量在2010、2020、2030、2040和2050年将分别达到8.1～8.8、19.6～25.7、18.4～33.0、20.3～34.9和23.6～35.4 TgC.退耕地造林林木生物质碳贮量占云南省退耕还林工程林木生物质碳贮量的33%～41%.     

陕北黄土丘陵沟壑区退耕还林工程贮碳潜力分析

以榆林南6县(米脂、佳县、绥德、吴堡、子洲和清涧县)为例,收集并调查了研究区森林清查资料及退耕还林的面积,运用森林蓄积量与生物量的关系为基础植物的碳估量方法以及土壤碳含量测定方法,对其贮碳现状进行了评估;在此基础之上,利用研究区退耕还林工程主要造林树种的生长曲线,对其贮碳量潜力进行了预测.结果表明:研究区县域退耕还林工程贮碳量在2010和2020年分别为20.64×104 ～ 100.09 × 104 mg C和预计25.97×104～ 126.14×104 mg C; 2010年按其大小排序为:绥德县＞佳县＞子洲县＞米脂县＞清涧县＞吴堡县;2020年预计排序为绥德县＞子洲县＞佳县＞米脂县＞清涧县＞吴堡县.县域退耕还林工程具有明显的贮碳潜力.     

退耕还林工程植被碳汇效益估算

利用全国森林资源连续清查的人工林统计数据,建立了不同树种(组)人工林生物量密度—林龄模型,并根据全国退耕还林工程退耕地还林阶段验收有关结果数据,分析估算了全国退耕还林工程植被碳汇量及碳汇价值。     

张掖森林公园林木碳汇计算与价值评价

选取张掖市森林公园人工林作为河西荒漠区人工林的典型林分,针对不同林分类型分别设置样地,采用单株蓄积量法对张掖森林公园现有人工林的碳汇量与价值进行计算与评价研究,研究表明:张掖森林公园林分蓄积量、碳储量、碳汇价值及林分全部碳汇经济价值最高的为落叶阔叶林,其次常绿针叶林、宿根花卉及地被物、经济林、落叶花灌木。     

湖南省杉木林植被碳贮量、碳密度及碳吸存潜力

基于湖南省2005和2010年森林资源调查统计数据,结合国家野外科学观测研究站湖南会同杉木林生态系统定位研究站的观测数据,估算湖南省杉木林植被碳贮量、碳密度及碳吸存潜力.结果表明:2005和2010年湖南省杉木林植被碳贮量分别为30.39×106和32.92×106t,均以中龄林的碳贮量最高,分别为17.64×106和17.31×106t; 2010年各地州市杉木林植被碳贮量为0.34×106～6.45×106t;杉木林碳密度随林分龄级增加而增高,过熟林最大(23.90 tC·hm1以上),2005和2010年湖南省杉木林平均碳密度分别为10.83和12.05 tC·hm-2,各地州市杉木林植被碳密度为6.03 ～16.58 tC·hm-2,基本上呈现出南高北低的趋势;湖南省杉木林植被的现实碳吸存潜力为90.75×106t,不同龄级林分的现实碳吸存潜力表现为中龄林(53.62×106t)＞近熟林(32.77×106t)＞幼龄林(4.36×106t),各地州市杉木林植被的现实碳吸存潜力为1.18×106 ～ 17.39×106t;湖南省(2010年)现有未成熟杉木林到2020年时的固碳潜力为176.77 × 106t,年固碳潜力为17.68×106t·a-1,到达成熟阶段(26年生)时固碳潜力为211.67×106t.湖南省杉木林分质量不高,中幼龄林所占比重较大,若能对现有杉木林加以更好的抚育管理,湖南省杉木林仍有很大的碳汇潜力.     

基于固碳增汇的日本落叶松经营技术研究

全球碳排放一直是大众关注的重点。近几年随着我国不断出台的碳排放政策,配套的相关研究也出现很高的热度。以日本落叶松林为对象,为探究日本落叶松林生长发育规律以及最优碳汇增长模式,以固碳增汇模式规划其抚育方式,设计了经营方案。采用划分林分生长阶段,在固碳增汇经营目标指导下,规划出不同林龄、不同林分应该对应的不同固碳增汇经营方式。主要研究结论如下：(1)根据前期调查结果,根据现有林分特征从林木类型划分、目标直径确定、目标树密度确定、目标林相预期、抚育采伐、林下更新与植物保护等方面探讨了日本落叶松林固碳增汇经营技术要素;(2)基于固碳增汇技术与理论,结合日本落叶松林木生长规律,将其划分为4个固碳增汇经营阶段,并将4个阶段与普通森林群体的生长发育阶段相结合,针对不同立地条件,给出适用于不同阶段的经营措施;(3)提出日本落叶松林固碳增汇经营技术,该技术能有效改善林分碳汇增长量,实现碳汇价值,通过阶段性抚育作业,实现单调的用材目标向碳汇用材双目标的转变;(4)通过调查不同初植密度下10年生日本落叶松单株碳汇量,发现当初值密度为2400～2500株/hm²时10年单株碳汇量最高,公...     

华南地区主要造林树种林分碳储量估算

研究52 个乔木树种纯林的碳储量,分析其固碳能力差异,为碳汇造林选用乔木树种提供参考 依据。以广东省东江林场11 年生的乔木树种试验林为研究对象,测定52 个树种生长量和树干、树枝和 树叶的含碳率。按照平均木法,算出平均木生物量,结合平均含碳率、林分密度与保存率,估算碳储量。 结果表明,不同树种林分碳储量差异极大,最高碳储量（厚荚相思Acacia farnesiana）比最低碳储量（紫 玉兰Magnolia liliiflora）相差约20 倍,年均碳储量在10 t/hm2 以上的树种有含羞草科的厚荚相思、大叶 相思A. auriculiformis 等5 个树种,年均碳储量在5~10 t/hm2 的有灰木莲Manglietia glanca、红荷Schima wallichii 等18 个树种。以保存率和单位面积碳储量2 个主要性状作聚类分析,可将52 个树种按固碳能力 划分成4 种类型的碳汇树种。     

Carbon sequestration potential of the stands under the Grain for Green Program in Yunnan Province,China

The carbon sequestration potential in living biomass and soil organic matter under the Grain for Green Program (GGP) in Yunnan Province, one of the most important target provinces of the GGP in China, was estimated in this paper using empirical curves and factors. The area of tree species planted during 2000–2007 was collected, and four scenarios for the annual area of GGP-stands to be planted during 2008–2010 and harvest options were schemed. Empirical growth curves for different tree species were developed based on data about the growth of existing plantation in Yunnan Province from National Forestry Inventory, and were used for the estimation of the carbon stocks in the tree biomass pools by incorporating with basic wood density, biomass expansion factors and carbon fraction. Empirical factors were introduced to estimate the stock change in soil organic carbon (SOC) under the GGP. The results show that the carbon stock in the GGP-stands in Yunnan Province will increase by 12.474–12.608 TgC, 33.016–35.161 TgC, 38.119–47.100 TgC, 43.057–53.626 TgC and 49.918–56.621 by the year 2010, 2020, 2030, 2040 and 2050, respectively. The annual carbon stock change in the GGP-stands will peak at 2.342–2.536 TgC per year in 2013, followed by a gradual decrease. The estimated potential carbon sequestration by GGP-stands amounts to 10.82–12.27% of the carbon stocks of forest ecosystems in Yunnan province in the 1990s.     

Tree species composition affects productivity and carbon dynamics of different site types in boreal forests

The objective was to analyse how differences in the initial proportions of tree species and site fertility affect carbon sequestration in living biomass and soil. We used the individual-based simulation model EFIMOD, which is able to simulate spatially explicit competition between trees for light and nutrients. Simulations were carried out for three site types with distinct initial stocks of soil nutrients. For each site, the 100-years undisturbed dynamics of monocultures and mixtures of three tree species (Betula pendula Roth, Pinus sylvestris L. and Picea abies (L.) H. Karst.) was predicted. Changes in the proportions of competing tree species were dependent on the fertility of the site: on poor sites, pine was the most competent species, while on rich sites, spruce increased its proportion during stand succession. Net primary production (NPP) and soil respiration were the highest in stands of two coniferous species and in stands with a high initial proportion of pine. Mixed stands were more productive than monocultures; the highest overyielding was observed with mixtures of two coniferous species. Simulated NPP and carbon stocks in all pools increased from poor to rich sites. The highest carbon stocks in standing biomass were observed for mixtures of conifer species and three-species mixtures; the greatest accumulation of forest floor occurred in stands with high proportions of pine.     

Carbon stocks and soil respiration rates during deforestation, grassland use and subsequent Norway spruce afforestation in the Southern Alps, Italy

Changes in carbon stocks during deforestation, reforestation and afforestation play an important role in the global carbon cycle. Cultivation of forest lands leads to substantial losses in both biomass and soil carbon, whereas forest regrowth is considered to be a significant carbon sink. We examined below- and aboveground carbon stocks along a chronosequence of Norway spruce (Picea abies (L.) Karst.) stands (0-62 years old) regenerating on abandoned meadows in the Southern Alps. A 130-year-old mixed coniferous Norway spruce-white fir (Abies alba Mill.) forest, managed by selection cutting, was used as an undisturbed control. Deforestation about 260 years ago led to carbon losses of 53 Mg C ha(-1) from the organic layer and 12 Mg C ha(-1) from the upper mineral horizons (Ah, E). During the next 200 years of grassland use, the new Ah horizon sequestered 29 Mg C ha(-1). After the abandonment of these meadows, carbon stocks in tree stems increased exponentially during natural forest succession, levelling off at about 190 Mg C ha(-1) in the 62-year-old Norway spruce and the 130-year-old Norway spruce-white fir stands. In contrast, carbon stocks in the organic soil layer increased linearly with stand age. During the first 62 years, carbon accumulated at a rate of 0.36 Mg C ha(-1) year(-1) in the organic soil layer. No clear trend with stand age was observed for the carbon stocks in the Ah horizon. Soil respiration rates were similar for all forest stands independently of organic layer thickness or carbon stocks, but the highest rates were observed in the cultivated meadow. Thus, increasing litter inputs by forest vegetation compared with the meadow, and constantly low decomposition rates of coniferous litter were probably responsible for continuous soil carbon sequestration during forest succession. Carbon accumulation in woody biomass seemed to slow down after 60 to 80 years, but continued in the organic soil layer. We conclude that, under present climatic conditions, forest soils act as more persistent carbon sinks than vegetation that will be harvested, releasing the carbon sequestered during tree growth.     

贵州省退耕还林工程主要树种碳汇潜力预测

利用贵州省2000-2007年各类退耕还林面积和树种数据,设定了2008～2010年间的4种年度造林面积情景。再依据贵州省森林资源清查中不同树种的的历史数据和生长参数建立生长方程,并结合生物量扩展系数、木材密度和碳含量等参数,预测出贵州省未来50年不同情景下的退耕还林主要树种树生物质碳储量及变化。结果表明在2010、2020、2030、2040、2050年,6大造林树种的总碳储量分别达到4．54～4．82TgC、11．02～13．47TgC、14．77～18．92TgC、10．69～21．83TgC、12．52～23．47TgC,占总退耕还林工程的43％-51％。     

Spatially explicit assessment of carbon stocks of a managed forest area in eastern Germany

The Kyoto-protocol permits the accounting of changes in forest carbon stocks due to forestry. Therefore, forest owners are interested in a reproducible quantification of carbon stocks at the level of forest management units and the impact of management to these stocks or their changes. We calculated the carbon stocks in tree biomass and the organic layer including their uncertainties for several forest management units (Tharandt forest, Eastern Germany, 5,500 ha) spatially explicit at the scale of individual stands by using standard forest data sources. Additionally, soil carbon stocks along a catena were quantified. Finally, carbon stocks of spruce and beech dominated stands were compared and effects of thinning intensity and site conditions were assessed. We combined forest inventory and data of site conditions by using the spatial unions of the shapes (i.e., polygons) in the stand map and the site map. Area weighted means of carbon (C) stocks reached 10.0 kg/m2 in tree biomass, 3.0 kg/m2 in the organic layer and 7.3 kg/m2 in mineral soil. Spatially explicit error propagation yielded a precision of the relative error of carbon stocks at the total studied area of 1% for tree biomass, 45% for the organic layer, and 20% for mineral soil. Mature beech dominated stands at the Tharandt forest had higher tree biomass carbon stocks (13.4 kg/m2) and lower organic layer carbon stocks (1.8 kg/m2) compared to stands dominated by spruce (11.6, 3.0 kg/m2). The difference of tree biomass stocks was mainly due to differences in thinning intensity. The additional effect of site conditions on tree carbon stocks was very small. We conclude that the spatially explicit combination of stand scale inventory data with data on site conditions is suited to quantify carbon stocks in tree biomass and organic layer at operational scale.     

Effect of tree species on carbon stocks in forest floor and mineral soil and implications for soil carbon inventories

Forest soil organic carbon (SOC) and forest floor carbon (FFC) stocks are highly variable. The sampling effort required to assess SOC and FFC stocks is therefore large, resulting in limited sampling and poor estimates of the size, spatial distribution, and changes in SOC and FFC stocks in many countries. Forest SOC and FFC stocks are influenced by tree species. Therefore, quantification of the effect of tree species on carbon stocks combined with spatial information on tree species distribution could improve insight into the spatial distribution of forest carbon stocks.We present a study on the effect of tree species on FFC and SOC stock for a forest in the Netherlands and evaluate how this information could be used for inventory improvement. We assessed FFC and SOC stocks in stands of beech (Fagus sylvatica), Douglas fir (Pseudotsuga menziesii), Scots pine (Pinus sylvestris), oak (Quercus robur) and larch (Larix kaempferi).FFC and SOC stocks differed between a number of species. FFC stocks varied between 11.1 Mg C ha⁻¹ (beech) and 29.6 Mg C ha⁻¹ (larch). SOC stocks varied between 53.3 Mg C ha⁻¹ (beech) and 97.1 Mg C ha⁻¹ (larch). At managed locations, carbon stocks were lower than at unmanaged locations. The Dutch carbon inventory currently overestimates FFC stocks. Differences in carbon stocks between conifer and broadleaf forests were significant enough to consider them relevant for the Dutch system for carbon inventory.     

Simulation of carbon pool changes in woodlots in eastern Zambia using the CO2FIX model

Agroforestry systems have the potential to contribute significantly to climate change mitigation and adaptation. However, data on tree and soil organic carbon (SOC) pools for most agroforestry systems are lacking because reliable methods for estimating ecosystem carbon (C) pools are scarce. This study quantified the effects of five Leucaena species (L. leucocephala, L. macrophylla, L. diversifolia, L. collinsii and L. pulverulenta) on vegetal and soil C stocks and on mean annual increment (MAI) in aboveground tree C stocks. Specifically, it tested the validity of the CO2FIX model using empirical data from 7?year-old woodlots at Msekera, Zambia, and assessed the impact of converting a degraded agricultural ecosystem to woodlots on C stocks. Measured above- and below-ground tree C stocks and MAI of aboveground biomass differed significantly among the Leucaena species. Measured stem and total aboveground tree C stocks in seven-year old woodlots ranged from 17.1 to 29.2 and from 24.5 to 55.9?Mg?ha^?1, respectively. Measured SOC stocks at 0?C200?cm depth in Leucaena stands ranged from 106.9 (L. diversifolia) to 186.0?Mg?ha^?1 (L. leucocephala). Modeled stem and branch C stocks closely matched measured stocks, but the soil module of CO2FIX did not predict the soil C. The soil C data are inconclusive at this stage. We recommend that a fractionation and a soil aggregate hierarchy study backed by C dating is carried out to explain soil C dynamics in these soils. However, the model can be used only for estimating changes in aboveground tree C stocks in woodlots until soil C module is proven to predict SOC stocks.     

Rapid carbon accumulation within an unmanaged,mixed, temperate woodland

Forest carbon stocks have increased in both Europe and North America in recent decades. National forest inventories are often used to indicate recent carbon dynamics, but the data from unmanaged forests are often incomplete. Here we calculate changing biomass carbon stocks for a mixed, unmanaged British woodland with two different management histories: (1) older growth stands untouched since 1902 and (2) younger growth stands clear felled in 1943 but have developed naturally since. Transects in the older growth have been monitored since 1945 and the younger growth since 1977. Separate estimates of tree carbon (C), soil C and dead wood C were obtained to verify how C is apportioned in these stands. Tree biomass C stocks had approximately doubled in the older growth stands since 1945 and 60% of C was stored in tree biomass, 38% was stored in soil and 2% stored in coarse woody debris. This study suggests that natural older growth stands are storing more C than typical managed forests, with tree biomass the most important compartment for C stores. If management is to be shifted from biomass production to increased C stores, due consideration should be given to the role of unmanaged, older growth forests.