Introduction

Forest Ecosystems store the greatest amounts of carbon in terrestrial ecosystems and are important in global C cycling and climate change(Dixon et al.1994;Pan et al.2011).Forest ecosystem carbon storage has been reported at global,national and regional scales(Durán et al.2015;Holdaway et al.2014;Kohl et al.2015;Pan et al.2011;Poorter et al.2015).China as the largest developing country in the world has the largest area of plantation forests(Streets et al.2001).After the new social system was established in 1949,rapidly increasing population and economic development have resulted in increased forest exploitation and environmental degradation across the country,especially 1949–1963 and 1976–1980.In order to reduce environmental degradation,China’s government launched a series of national key forest programs beginning in the late 1980s,including: ‘Natural Forest Protection Program’, ‘Deserti fi cation and Dust Storms Control Program in the vicinity of Beijing and Tianjin Municipalities’,‘Forest Shelterbelt Development Program in key environmentally fragile regions’, ‘Wildlife Conservation and Nature Reserves Development Program’and ‘Fast-growing and High-yield Timber Plantations Program’,in the late 1990s,Grain for Green Program has played an important role in the restoration of vegetation.(Sylvie et al.2009).These programs increased forest area and the amounts of carbon stored in China’s forest ecosystems.

China’s forest vegetation carbon storage,carbon density and spatial distribution have been quanti fi ed using various methods at regional and national scales(Fang et al.2001;Piao et al.2005;Ren et al.2011,2013,2014).Differences in the regional distribution of forests, fi eld data collection methods,and analytical methods have resulted in varying estimates of forest vegetation carbon storage in China.For example,Wang et al.(2001)estimated forest vegetation carbon storage based on the 38 dominant tree species in China at 3724 Tg.In contrast,Fang et al.(1998)estimated China’s forest ecosystem carbon storage at 4300 Tg while Dixon et al.(1994)estimated 17,000 Tg.Forest carbon sequestration is closely related to forest area,forest age structure and forest species(McKenney et al.2004).Many studies showed that carbon density varies by forest vegetation type and by forest age class(Guan et al.2015;Fang et al.1998;Ren et al.2013;Wang et al.2015).To account for regional variation in carbon storage estimates caused by forest type and research methods,it is necessary to estimate China’s forest carbon storage using a regional approach.

物联网技术架构主要分为三个层次：感知层、网络层（又称传输层）和应用层。感知层是实现物联网的基础，主要利用各种传感器设备完成信息的采集、转换和收集。网络层通过各种长距离或短距离、有线及无线通信技术完成感知数据的传输。应用层通过各种数据处理呈现人机交互技术，满足不同行业用户的信息化业务应用需求，如监控类（车辆监控、温湿度监测）、查询统计类（远程抄表、资产管理）以及控制类（智慧路灯、智能家居、智能楼宇）等不同类型的应用。

In China,Ren et al.(2011)used forest inventory data to determine that total forest vegetation carbon storage increased in Fujian Province from 136.5 Tg in 1978 to 229.3 Tg in 2008.Guan et al.(2015)estimated carbon storage increased from 83.1 Tg in 1979 to 100.7 Tg in 2006 in Gansu Province,depending on the relevant forest inventory data and empirical factors.These estimations of forest carbon stocks covered short time spans.

Henan Province,in east-central China,supports 359.1×104ha of forest land that covers 21.5% of the province.Forest inventory data for Henan Province cover the years 1949–2008 yet the dynamics of forest biomass carbon stocks during this time period have not been reported.In this study we analyzed these forest inventory data(FID; fi eld data collected by Henan Province Forestry Bureau)to estimate carbon storage by forest vegetation from 1949 to 2008.Our objectives were to:(1)estimate carbon storage and density by forest type,age class,forest category,and forest origin;and(2)to describe forest carbon storage dynamics in Henan Province over this 60-year period.

Materials and methods

Study area

Henan Province is located in east-central China at 31°23′to 36°22′N and 110°21′to 116°39′E,in the middle and lower reaches of the Yellow River.The total land area is 1670×104ha,including 720×104ha of farmland and 740×104ha of hilly area.Henan Province is a transitional zone between subtropical and warm temperate regions of China,with a humid and semi-humid monsoon climate.Annual rainfall ranges from 500 to 900 mm and annual average temperature is 12–16 °C.Based on the Soil Taxonomy of China(Henan Province Soil Survey Of fi ce 2004),Henan soil types are mainly brown,cinnamon,yellow–brown,yellow-cinnamon, fl uvo-aquic,lime-concretion black,and saline-alkali soils.Southern warm temperate deciduous broad-leaved forests and northern subtropical evergreen broad-leaved forests are the main vegetation types in the region.Henan supports 197 plant families represented by 1191 genera and 4473 species,accounting for 12.2% of China’s fl ora.

我国西部地区政府审计揭示效率实证分析——基于DEA和Malmquist指数模型的研究贺宝成 王家伟20-69

Data source

Estimating the biomass of open forests and shrub forests

China’s forest resource inventory de fi ned fi ve distinct forest groups or categories:forest stands,economic forests,bamboo forests,open forests and shrub forests.For each of these forest groups,the forest inventory documented the areas and timber volumes for dominant tree species for forest stands by fi ve age classes(young,middle-aged,premature,mature and post-mature),four forest categories(timber,shelter,fuelwood,special use forest)and two sources of forest origin(plantations and natural forests).For the nine listed forest inventory periods,only total forest area was calculated for economic,bamboo,open,and shrub forests.

The total forest area increased from 231.9×104ha in 1949 to 404.5 × 104ha in 2008.During the periods 1950–1963 and 1977–1980 total forest area decreased(Fig.1).Beginning in 1980,forested area increased steadily.Notably,the area of afforestation increased signi fi cantly from 339.2× 104to 404.5× 104ha in 1999–2008.From 1949 to 2008,total vegetation carbon storage increased by 132%from 34.6 to 80.3 Tg,while forest vegetation carbon density increased by 30%from 14.9 to 19.9 Mg ha-1(Fig.1).The forest vegetation biomass carbon sinks varied greatly by time period:the carbon sinks in 1950–1963 and 1977–1980 were negative,implying forest vegetation had been damaged in these two periods.The forest biomass carbon sink increased from -2.782 Tg a-1in 1977–1980 to 4.120 Tg a-1in 2004–2008.

AREA and CARBON are the forest stand area(104ha)and biomass C stock(Tg)in a province,respectively;subscripts 0.3 and 0.2 represent the criterion of＞30 and 20%canopy coverage,respectively.

对于孔子已经评价过的人物，司马迁常常是直接采取孔子的评价，例如称吴太伯为“至德”，称微子、箕子、比干为殷之“三仁”，称董狐为“良史”，赵盾为“良大夫”，子产为“古之遗爱”。这些都是孔子已经评价过的人物，司马迁便因袭孔子的观点，直接以孔子的评价作为自己的评价。而对于孔子以后或者孔子所未评论到的人物，司马迁也非常善于使用孔子留下来的概念来进行评价，如评价吕不韦为“闻”，评价万石、建陵、张叔为“君子”，评价田叔“居是国必闻其政”，这都是借用孔子留下的现成概念或标准来评价人物。由此我们可以看出，在评价历史人物时，孔子的评价标准也是司马迁的重要价值尺度，甚至取舍褒贬都与孔子一致。

From 1976 to 2008,the area,carbon storage and carbon density of natural forest changed little.Natural forest area increased from 95.9×104to 118.7×104ha,accounting for 42–73% of the total forest stand area.Carbon storage was between 18.3 and 31.3 Tg accounting for 45–85% of the total forest stands carbon storage,meanwhile,the carbon density ranged from 18.0 to 26.3 Mg ha-1.Compared to natural forests,planted forests increased in area,carbon storage and carbon density remarkably.The area of planted forest increased from 38.1×104to 160.8×104ha,accounting for 27–58% of the total forest stand area.From 1998 to 2008 the area of planted forest increased from 53.9×104to 160.8×104ha.From 1976 to 2008,carbon storage of planted forest increased from 3.9 Tg to 37.9 Tg,accounting for 15–55% of the total forest stand carbon storage.Increased carbon storage was 33.7 Tg,or 82% of the total forest stand carbon storage increment(41.0 Tg),and average annual sequestration of 1.1 Tg of carbon.The carbon density of planted forest increased from 8.9 Mg ha-1in 1976 to 23.6 Mg ha-1in 2008.

where C1represents the cellulose content,C2is the hemicellulose content,C3is the lignin content.Cellulose,hemicellulose and lignin content for various species were obtained from the literature(Jiang and Peng 2001;Wang and Ding 1985)(Table 1).We used a ratio of 0.5 to convert biomass to carbon stock for bamboo forests,economic forests,open forests and shrub.

Estimating the biomass of forest stands

The biomass of trees was calculated using the continuous BEF method(Fang et al.2001)with a regression equation as follows:

where B is the biomass per hectare(Mg ha-1),V is the volume per hectare(m3ha-1),and a and b are parameters converting from volume to biomass for given tree species.

We estimated biomass carbon stocks by multiplying the mean biomass density by the area of economic forests in each inventory period.For mean biomass density we use the value of 23.7 Mg ha-1(Fang et al.1996).

当前，大多数制造企业在成本管理中，总是存在成本管理体系缺失的状况。完善的成本管理体系中，涉及了事前管理、事中管理及事后管理等内容。同时也还具备规范的动态成本管理体系。在实际中，制造企业在实施成本管理工作时，把工作重心放置在事中及事后管理上，缺少预控管理。事后管理通常展现在成本核算上，没有深入实现成本核算，这给企业后续成本控制开展带来不利影响。一个完善的成本管理体系中包含了成本预算体系、成本规划体系、成本决策体系等诸多内容，假设缺少其中一项，都是给成本管理结果带来直接影响。

Estimating the biomass of economic forests and bamboo forests

Henan Province forest resources inventory data included 12 dominant tree species.Where the biomass of Larix,Cunninghamia lanceolata,poplar,and Paulownia in Henan Province have been quanti fi ed(Feng et al.1992;Wang 1999;Zeng 2005;Zhao 1989;Zhao et al.1999),we used the estimated parameters derived from these studies.Fang et al.(2001)derived formulae for converting volume to biomass for 21 dominant forest types in China.Five of the derived formulae were suited for Henan Province forests and were used in this study(Table 1).The parameters for three additional forest species groups including mixed conifer forest,mixed conifer and broadleaved forest and mixed broadleaved forest were taken from Zeng(2005),and these were suited for Henan Province.

Henan’s forest inventory documented the areas of moso bamboo and other bamboo forests.We estimated bamboo forest biomass carbon stocks by using the mean biomassdensity for each bamboo type multiplied by the area.We used the estimates of Guo et al.(2013)for the mean biomass density of moso bamboo and other bamboo forests(81.9 and 53.1 Mg ha-1,respectively).

Table 1 Parameters used to calculate biomass of forest stands and carbon fraction for different dominant tree species

Dominant tree species a b N R2 References Carbon fraction(CF)Platycladus orientalisb 0.6129 46.1451 11 0.98 Fang et al.(2001) 0.5034 Larix 0.5442 16.1235 35 1.00 Zhao et al.(1999) 0.5211 Pinus tabulaeformis 0.7554 5.0928 82 0.98 Fang et al.(2001) 0.5207 Pinus massoniana 0.5101 1.0451 12 0.92 Fang et al.(2001) 0.4596 Cunninghamia lanceolata 0.5371 11.9858 29 1.00 Wang(1999) 0.5201 Quercus 1.1453 8.5473 12 0.98 Fang et al.(2001) 0.5004 Hardwood forests 0.7564 8.3103 11 0.98 Fang et al.(2001) 0.4834 Populus 0.981 0.004 10 0.99 Zhao(1989) 0.4956 Paulownia 0.8956 0.0048 22 0.99 Feng et al.(1992) 0.4695 Mixed conifer forests 0.589424.5151–– Zeng(2005) 0.5101 Mixed broadleaf forests 0.83629.4157–– Zeng(2005) 0.4900 Mixed conifer and broadleaf forests0.714316.9654–– Zeng(2005) 0.4978

Henan’s forest resource inventory database spans nine periods: 1949, 1950–1963, 1973–1976, 1977–1980,1984–1988,1989–1993,1994–1998,1999–2003 and 2004–2008.Inventory data were recorded using a systematic sampling method implemented by Henan Province Forestry Department.Mapped forest areas were overlaid with a 4×4 km grid and square plots covering 28.28×28.28 m were systematically sampled within each grid cell.Sampling methods were adjusted depending on the type of forest cover.The forest resource survey data of 1949 and 1963 were estimated by Henan Province forestry department in 1990 by using the predict equation(Li 1999).There are over 5399 permanent sample plots spread across Henan Province that have been systematically sampled for forest resource inventory from 1980 to 2008.

The Qinling Mountains–Huaihe River form the geographical boundary between south and north China.The distribution area of open forests and shrub forests in China are divided into three regions,viz.south Qinling Mountains–Huaihe River Line,northeast of Qinling Mountains–Huaihe River Line,and northwest China.In these three districts the mean biomass densities are 19.76,13.14 and 13.9 Mg ha-1(Fang et al.1996).Henan Province is located northeast of the Qinling Mountains–Huaihe River Line so we adopted a mean biomass density of 13.14 Mg ha-1to estimate the open forest and shrub-forest biomass density.The total biomass of open forests and shrub-forest was calculated by multiplying the average biomass density by the total area(calculated by Forestry Department of Henan Province).

Results

Change in forest area,forest biomass carbon storage and carbon sink

In 1994,the de fi nition of forest stands in China’s forest resource inventory was changed from＞30%canopy coverage to＞20%canopy coverage.In order to make our results comparable among different periods,Guo et al.(2013)modi fi ed the equations of the two criteria for the forest area and biomass C stocks at the provincial level for achieving more accurate conversion between 20 and 30%canopy coverage.In this study,we used their equations as follows to produce better estimates(Guo et al.2013).

1.流行的时代性。流行音乐发展更新的速度非常快，“90后”和“00后”喜欢的流行音乐形式以及流行歌手会大不相同。这就要求音乐教师要与时俱进，了解新生的流行音乐以及流行歌手，把握学生的喜好，这样才能更好地发挥流行音乐在促进学生审美提高中的作用。

多运营主体梯级水电站参与的日前市场出清模型//张粒子,刘方,许通,蔡华祥,蒋燕,徐宏//(16):104

During the period 1949–2008,carbon storage and carbon density dynamics varied by forest type(Table 2).Accounting for 53–72% of total forested area,forest stands stored 72–86% of total biomass carbon storage and net accumulated carbon of 39.7 Tg over the 60-year period,at an average carbon accumulation rate of 0.674 Tg a-1.This accounted for 87% of total biomass carbon sink during 1949–2008.The area-weighted mean of biomass carbon density also increased from 18.6 Mg ha-1in 1949 to 24.4 Mg ha-1in 2008.Maximum forest stand carbon sink was estimated for 2004–2008 at 4.576 Tg a-1.These results con fi rm that carbon stored in forest stands had the most in fl uence on total forest vegetation carbon storage.Over the past six decades,the increase of carbon storage in economic forests,bamboo forests,open forests and shrubforests was mainly due to the increase in forested area and tree growth.The sum of carbon storage of economic forests,bamboo forests,open forests and shrub-forests accounted for 14–28% of total forest vegetation carbon storage in different inventory periods.

We categorized forest stands as coniferous and broadleaved forests.Coniferous forest area accounted for 8.4,43.1,19.3,19.5,19.5,24.2,24.5,17.8 and 12.1%,respectively,of Henan Province’s total area of forest stands in the nine inventories from 1949 to 2008.Carbon storage estimates for the nine periods were 2.3,9.1,4.6,4.1,5.1,7.2,7.5,4.9 and 5.7 Tg,accounting for 7.7,46.9,16.4,18.6,18.8,23.4,24.3,10.5 and 8.2%,respectively,of total forest stand carbon storage in the corresponding inventory periods(Fig.4).

Biomass carbon storage and density of forest stands by age class

Fig.1 The change of area and carbon stocks in Henan Province’s forests during 1949–2008

b forests d shru forests an Open sink on Carb g a-1)(T Carbon storage g)(T Area(104ha)0.067-0.203-0.347 0.174 0.042 0.328.031-0.012-0.001-0 4.5 5.5 2.8 1.4 2.8 3.0 4.7 4.5 4.4 68.7 83.1 42.9 21.8 43.0 46.2 71.2 68.9 67.9 sink on Carb g a-1)(T 0.006 0.053 51-0.1 01-0.0 0.031 0.044-0.008 0.022 0.010 forests oo Bamb Carbon storage g)(T a)Area(104h 0.02 0.11 0.80 0.19 0.19 0.34 0.56 0.52 0.63 0.1 0.4 3.0 0.7 0.7 1.3 1.9 1.8 2.1 08 20 to 1949 from Henan Province pes in ty anges for different forest ch stocks d carbon an e area ble 2 Th Ta forests ic Econom stands Forest Period sink on Carb g a-1)(T on Carb storage g)(T a)Area 04h(1 sink Carbon g a-1)(T density on Carbg ha-1)(M Carbonestorag g)(T a)Area(104h 14-0.0 0.498 99-0.7 0.026 0.239 0.341 0.320-0.466 0.092 0.6 0.4 6.9 3.7 3.9 5.1 6.8 8.4 6.1 5.1 3.41.1 58 31.1 32.8 42.9 57.3 70.8 51.1.7162 644 2-00.67-1.485 0.58 0.82–0.0 3.098 4.576 0.674 18.6 13.9 19.0 15.9 17.2 18.7 20.6 23.4 24.4.4 29 1298.4.1 22 26 31 30 46 69.2.9.0.8.3.2 158.0 139.3 148.4 139.2 156.0 165.4 149.8 197.7 283.4 3 96 6 97 0 98 838388 1949 1950–1 1973–1 1977–1 1984–198 1989–199 94–199 19 99–200 19 04–200 20 49–200 19

Forest carbon is closely related to forest age composition(Liu et al.2000).In the early forest resource inventory data,forest stands only were grouped into three forest age classes(young,middle-aged,mature).After the inventory period of 1984–1988,forest stands were grouped into fi ve age classes(young,middle-aged,premature,mature and post-mature).To enable comparison of all inventory data,we included premature,mature,and post-mature forest into a single age class we named old–aged forest.The temporal change of area,carbon storage,and carbon density among three age classes of forest stands are shown in Fig.2.Carbon storage was mainly distributed in the young and middle-aged forests,whose area accounted for 87–97% of the province’s total forest area in different periods.Carbon storage in various periods accounted for 70–88% of total forest stand carbon storage.Old-aged forest area accounted for 3–13% of the total forest stand area and carbon storage accounted for 12–30% of total forest stand carbon(Fig.2).Carbon densities ranked by age class in descending order as:old-aged＞middle-aged＞young(Fig.2).

Biomass carbon storage and density of forest stands in planted and natural forests

We analyzed data by forest origin(natural versus planted)for the inventory periods after 1963(previous records made no distinction).Temporal changes in forest area,carbon storage,and carbon density under planted and natural forests are shown in Fig.3.

We calculated carbon storage of forest vegetation by multiplying the amount of forest biomass by the carbon coef fi cient.We estimated forest biomass carbon stocks for each inventory period by using the continuous BEF method for forest stands,and the mean biomass density method for economic forests,bamboo forests,open forests and shrub forests.The coef fi cient of carbon of dominant tree species of the forest stands was obtained by the formula:

如何做好溃坝应急管理工作，涉及面很宽，上述简要论述乃非工程措施的一部分内容。从根本上说，所有大坝管理者都应当居安思危，未雨绸缪，防患未然，能及时发现大坝风险先兆才能取得主动。

Biomass carbon storage and density of different forest types in forest stands

Fig.2 Area,carbon storage and carbon density of Henan Province’s forest stands among different age classes during 1949–2008

主要考虑的是变极电机与不变极电机的差价。根据上海电机厂提供的参考价格,TL 1600—28/56同步电动机的价格约为150万元/台，而TL1600—28同步电动机的价格约为100万元/台,则每台变极电机要多投资 50万元，10台电机共计500万元；因电机体积增大而导致土建增加的经费约 60万元，10台合计600万元；其余费用与同转速发电相同。

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Fig.3 Area,carbon storage and carbon density of Henan Province’s forest stands in natural forest and planted forest during 1949–2008

Fig.4 Area,carbon storage and carbon density of Henan Province’s forest stands in conifer forest and broad-leaved forest during 1949–2008

Broad-leaved forests area accounted for 92,57,81,80,81,76,76,82 and 88% of the Henan Province’s total area of the forest stands in the nine periods from 1949 to 2008.And carbon storage amounts in the nine periods were 27.0,10.3,23.6,18.1,21.8,23.8,23.3,41.4 and 63.5 Tg,accounting for 92,53,84,81,81,77,76,90 and 92%,respectively,of the total forest stands carbon storage in the corresponding time.Forest biomass carbon was accumulated mainly in broad-leaved forests.During 1949–2008,the mean carbon density of broad-leaved forests was between 16.1 and 25.5 Mg ha-1and conifer forests ranged from 13.8 to 20.4 Mg ha-1(Fig.4).The broad-leaved forests had high carbon storage mainly attributed to the large broad-leaved forest area and high biomass density.Broad-leaved forest was the main contributor to forest carbon sequestration in Henan Province.

Biomass carbon storage and density of forest stands

by forest category

Based on the goals of forest management,Henan’s forest stands can be divided into four forest categories:timber,shelter,fuelwood,and special use.But the forest stands were not divided into these four categories between 1949 and 1976.From 1949 to 1998 the area of timber forest was greater than other forest categories,accounting for 96%,95%,91%,64%,61%,64%,67% of the total forest stand area(Table 3).The area of shelter forest surpassed that of timber forest in 2003 and 2008,reaching 48% of total area in both years.Reforestation and afforestation programsfocus on conservation of water and soil,causing the increasing area of shelter forest.The dynamic of carbon storage in different forest categories was consistent with the changing area of different forest categories.Carbon densities varied by forest category during the period 1949 to 2008:The carbon density of fuelwood forest was the lowest of all forest categories.In 2008,the carbon densities ranked by category as specialuse forest＞shelter forest＞timber forest＞fuelwood forest.

两台专业级相机无一例外采用了双卡槽设计，只不过存储媒介上有所差异。尼康D500采用的是XQD卡加SD卡（支持UHS-II标准）的设计。XQD卡无论性能还是价格都处于非常超前的状态，不过它也代表了相机存储媒介的未来。相比之下，富士X-H1的设计更加保守，采用了双SD（均支持UHS-II格式）卡槽。

Table 3 Area,carbon storage and carbon density of different forest categories for nine periods from 1949 to 2008 in Henan Province,China

Period Forest category Area(104) Carbon storage(Tg) Carbon density(Mg ha-1)1949 Timber forest 151.8 27.7 18.3 Shelter forest 6.4 1.6 25.2 Total 158.1 29.3 18.5 1950–1963 Timber forest 132.5 18.2 13.7 Shelter forest 7.0 1.2 17.5 Total 139.5 19.4 13.9 1973–1976 Timber forest 135.9 26.8 19.7 Shelter forest 9.0 1.3 14.3 Fuelwood forest 3.8 0.2 4.7 Total 148.7 28.2 19.0 1977–1980 Timber forest 89.2 13.4 15.1 Shelter forest 35.2 7.7 21.9 Fuelwood forest 15.2 1.1 6.9 Forest for special use 0.3 0.1 15.4 Total 139.8 22.2 15.9 1984–1988 Timber forest 94.9 16.0 16.9 Shelter forest 43.4 9.0 20.7 Fuelwood forest 15.0 0.9 6.2 Forest for special use 3.6 1.1 29.4 Total 156.9 27.0 17.2 1989–1993 Timber forest 105.6 19.3 18.3 Shelter forest 39.8 9.5 23.8 Fuelwood forest 16.9 1.2 6.8 Forest for special use 3.9 1.2 29.2 Total 166.2 31.2 18.7 1994–1998 Timber forest 100.4 19.4 19.4 Shelter forest 36.8 9.4 25.6 Fuelwood forest 8.7 0.6 7.2 Forest for special use 3.9 1.3 33.4 Total 149.8 30.7 20.6 1999–2003 Timber forest 87.7 17.7 20.2 Shelter forest 94.7 24.0 25.4 Fuelwood forest 6.0 0.3 4.6 Forest for special use 9.4 4.3 45.8 Total 197.7 46.3 23.4 2004–2008 Timber forest 126.1 29.5 23.4 Shelter forest 134.4 32.9 23.9 Fuelwood forest 2.4 0.1 5.0 Forest for special use 16.7 6.7 38.9 Total 279.5 69.2 24.7

Discussion

The increase of total forest vegetation carbon storage in Henan Province during 1949–2008 mainly resulted from a net increase of forest coverage rate by more than 74%over 60 years(Table 2).In 2008,the total forest vegetation carbon storage in Henan Province was 80.3 Tg,or 1% of the forest vegetation carbon storage of 7811.5 Tg in China.The forest vegetation carbon density in Henan Province in 2008 was lower than that of 40.0 Mg ha-1in China(Li and Lei 2010).This was due to the dominance of young and middle-aged forests in Henan Province at the time of the survey.Li et al.(2012)reported that the carbon storage and carbon density of Henan Province’s forest stands were 88.0 Tg and 31.0 Mg ha-1,respectively,both estimates exceeding ours.The main reason was the use of different methods to estimate forest carbon.The total carbon storage of Henan Province’s forest vegetation in 2008 was equivalent to 58% of Henan Province carbon emission in 2010(Li et al.2011)and 3.7% of China’s total carbon emission(estimated at 2200 Tg in 2010(Durban conference)).

During the period of 1949 to 2008,the forest carbon storage dynamics showed a trend of increasing.However,the forest carbon storage in 1950–1963 and 1977–1980 decreased,because of the government economic policy and lack of the regulatory measures for forests.From 1998 to 2008,the forest area and carbon storage increased drastically,this was signi fi cantly due to the Grain for Green Program was carried out in Henan Province.These results have demonstrated that reforestation and afforestation programs are important measures to increase the forest carbon sequestration.These results are consistent with previous studies(Ren et al.2013;Zhang et al.2009).

Broad-leaved forests stored more carbon than did coniferous forests in nine inventories from 1949 to 2008,due mainly to the greater area of broad-leaved forest and its higher carbon density.From 1998 to 2008,forest carbon storage increased sharply in plantations.This was because:(1)Many trees were planted during this period by the Grain for Green Program;and(2)good management practices were applied to the planted forests.The result of carbon density in natural forest is higher than in planted forest is consistent with the study from Guo et al.(2013),mainly because species diversity and productivity are greater in the former(Deng and Shangguan 2013).

Analyses is data sets covering 60 years are often subject to various sources of error.First,the most important errors may come from forest inventory data and the model parameters(regression coef fi cients a,b)converting forest volume to biomass.Forest inventory data used in our study speci fi ed the precision requirement in sampling design:the forest area and volume precision were required to be＞90%in Henan Province.In addition,the R square values of the equations used to convert timber volume to biomass were above 0.9 for most dominant tree species(Table 1).Therefore,the data and method used in this study have relatively high precision.Ren et al.(2013)analyzed the error in estimates of forest carbon storage in Guangdong Province,southern China.In their study,the forest area and volume only contributed a small error to forest C storage estimate.Larger errors were mainly caused by model parameters(regression coef fi cients a,b),which accounted for 97,97,and 96% of the total error in 1992,1997,and 2002,respectively.To improve the accuracy of model predictions,it is necessary to develop conversion parameters that are adjusted to fi t regional forest conditions.

For the economic forests,bamboo,open forests and shrub,the major error can be generated from the use of mean biomass density.In this study,we used a mean biomass density estimate that is a universal value abstracted from the literature.This might have introduced error due to the in fl uences of climate,site conditions,or management practices.To remove this source of error,it is necessary to develop regionally accurate estimates of mean biomass density for representative forest vegetation types.

由于山地与平原高差太大，河流出山口之后，于山麓地带形成大大小小的扇状地形，成都河流冲积平原实为联合扇状平原。

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