固碳林生态效益补偿的税收政策研究

固碳林所具有的生态效益已得到社会的广泛认同,因其具有外部经济性和准公共产品的特性,政府必须对固碳林的生态价值进行补偿。文章根据"庇古税"原理,提出政府可通过征收"碳税"来补偿固碳林生态效益这一观点,并构建了"碳税"政策体系。同时,还提出了与"碳税"体系相关的配套政策,包括固碳林生态效益补偿标准,"碳税"交易市场的建立等。最后,对构建"碳税"体系时可能存在的障碍进行了分析。

Effects of long-term elevated CO_2 on N_2-fixing,denitrifying and nitrifying enzyme activities in forest soils under Pinus sylvestriformis in Changbai Mountain

A study was conducted to determine the effects of elevated CO2 on soil N process at Changbai Mountain in Jilin Province, northeastern China （42°24＂N, 128°06＂E, and 738 m elevation）. A randomized complete block design of ambient and elevated CO2 was established in an open-top chamber facility in the spring of 1999. Changpai Scotch pine （Pinus sylvestris var. sylvestriformis seeds were sowed in May, 1999 and CO2 fumigation treatments began after seeds germination. In each year, the exposure started at the end of April and stopped at the end of October. Soil samples were collected in June and August 2006 and in June 2007, and soil nitrifying, denitrifying and N2-fixing enzyme activities were measured. Results show that soil nitrifying enzyme activities （NEA） in the 5-10 cm soil layer were significantly increased at elevated CO2 by 30.3% in June 2006, by 30.9% in August 2006 and by 11.3% in June 2007. Soil denitrifying enzyme activities （DEA） were significantly decreased by elevated CO2 treatment in June 2006 （P 〈 0.012） and August 2006 （P 〈 0.005） samplings in our study; no significant difference was detected in June 2007, and no significant changes in N2-fixing enzyme activity were found. This study suggests that elevated CO2 can alter soil nitrifying enzyme and denitrifying enzyme activities.

Carbon Sequestration in Forest Vegetation of Beijing at Sublot Level

Based on forest inventory data (FID) at sublot level,we estimated the carbon sequestration in forest vegetation of Beijing,China in 2009.In this study,the carbon sequestration in forest vegetation at sublot level was calculated based on net biomass production (ΔB) which was estimated with biomass of each sublot and function relationships between ΔB and biomass.The biomass of forested land was calculated with biomass expansion factors (BEFs) method,while those of shrub land and other forest land types were estimated with biomass,coverage and height of referred shrubs and shrub coverage and height of each sublot.As one of special forested land types,the biomass of economic tree land was calculated with biomass per tree and tree number.The variation of carbon sequestration in forest vegetation with altitude,species and stand age was also investigated in this study.The results indicate that the carbon sequestration in forest vegetation in Beijing is 4.12 × 106 tC/yr,with the average rate of 3.94 tC/(ha·yr).About 56.91% of the total carbon sequestration in forest vegetation is supported by the forest in the plain with an altitude of < 60 m and the low mountainous areas with an altitude from 400 m to 800 m.The carbon sequestration rate in forest vegetation is the highest in the plain area with an altitude of < 60 m and decreased significantly in the transitional area from the low plain to the low mountainous area with an altitude ranging from 200 m to 400 m due to intensive human disturbance.The carbon sequestration of Populus spp.forest and Quercus spp.forest are relatively higher than those of other plant species,accounting for 25.33% of the total.The carbon sequestration in vegetation by the forest of < 40 years amounts to 45.38% of the total.The carbon sequestration rate in forest vegetation peaks at the stand age of 30–40 years.Therefore,it would be crucial for enhancing the capability of carbon sequestration in forest vegetation to protect the forest in Beijing,to limit human disturbance in the transitional area from the plain to the low mountain area,and to foster the newly established open forest.

Regional Variation in Carbon Sequestration Potential of Forest Ecosystems in China

Enhancing forest carbon(C) storage is recognized as one of the most economic and green approaches to offsetting anthropogenic CO_2 emissions. However, experimental evidence for C sequestration potential(C_(sp)) in China's forest ecosystems and its spatial patterns remain unclear, although a deep understanding is essential for policy-makers making decisions on reforestation. Here, we surveyed the literature from 2004 to 2014 to obtain C density data on forest ecosystems in China and used mature forests as a reference to explore C_(sp). The results showed that the C densities of vegetation and soil(0–100 cm) in China's forest ecosystems were about 69.23 Mg C/ha and 116.52 Mg C/ha, respectively. In mature forests, the C_(sp) of vegetation and soil are expected to increase to 129.26 Mg C/ha(87.1%) and 154.39 Mg C/ha(32.4%) in the coming decades, respectively. Moreover, the potential increase of C storage in vegetation(10.81 Pg C) is estimated at approximately twice that of soil(5.01 Pg C). Higher C_(sp) may occur in the subtropical humid regions and policy-makers should pay particular attention to the development of new reforestation strategies for these areas. In addition to soil nutrients and environment, climate was an important factor influencing the spatial patterns of C density in forest ecosystems in China. Interestingly, climate influenced the spatial patterns of vegetation and soil C density via different routes, having a positive effect on vegetation C density and a negative effect on soil C density. This estimation of the potential for increasing forest C storage provided new insights into the vital roles of China's forest ecosystems in future C sequestration. More importantly, our findings emphasize that climate constraints on forest C sequestration should be considered in reforestation strategies in China because the effects of climate were the opposite for spatial patterns of C density in vegetation and soil.Enhancing forest carbon(C) storage is recognized as one of the most economic and green approaches to offsetting anthropogenic CO2 emissions. However, experimental evidence for C sequestration potential(Csp) in China's forest ecosystems and its spatial patterns remain unclear, although a deep understanding is essential for policy-makers making decisions on reforestation. Here, we surveyed the literature from 2004 to 2014 to obtain C density data on forest ecosystems in China and used mature forests as a reference to explore Csp. The results showed that the C densities of vegetation and soil(0–100 cm) in China's forest ecosystems were about 69.23 Mg C/ha and 116.52 Mg C/ha, respectively. In mature forests, the Csp of vegetation and soil are expected to increase to 129.26 Mg C/ha(87.1%) and 154.39 Mg C/ha(32.4%) in the coming decades, respectively. Moreover, the potential increase of C storage in vegetation(10.81 Pg C) is estimated at approximately twice that of soil(5.01 Pg C). Higher Csp may occur in the subtropical humid regions and policy-makers should pay particular attention to the development of new reforestation strategies for these areas. In addition to soil nutrients and environment, climate was an important factor influencing the spatial patterns of C density in forest ecosystems in China. Interestingly, climate influenced the spatial patterns of vegetation and soil C density via different routes, having a positive effect on vegetation C density and a negative effect on soil C density. This estimation of the potential for increasing forest C storage provided new insights into the vital roles of China's forest ecosystems in future C sequestration. More importantly, our findings emphasize that climate constraints on forest C sequestration should be considered in reforestation strategies in China because the effects of climate were the opposite for spatial patterns of C density in vegetation and soil.

Aboveground biomass and seasonal patterns of aboveground net primary productivity in five bamboo species in northern Laos

Aims Accurate estimates of bamboo biomass and net primary productivity(NPP)are required to evaluate the carbon sequestration potential of bamboo forests.However,relevant data that are important for climate change mitigation,have rarely been collected in regions outside of East Asia and India.Information on seasonal patterns of NPP and its components will enable the quantification of factors that influence the carbon balance in bamboo forests.In this study,we quantified the aboveground biomass(AGB)and aboveground NPP of five major bamboo species in northern Laos using monthly data collected over a 12-month period.Methods All live culms in 10,2 m×2 m plots(for one monopodial bamboo species:Indosasa sinica)and 30 clumps per species(for four sympodial bamboo species:Bambusa tulda,Cephalostachyum virgatum,Dendrocalamus membranaceus and Gigantochloa sp.)were numbered and measured at breast height.We set 10 or 20 litter traps per species to collect litterfall.Censuses of dead and recruited culms and litterfall collection were performed once per month for 12 months.Important Findings The AGB was highest in I.sinica(59.87 Mg ha^(-1))and lowest in C.virgatum(11.54 Mg ha^(-1)),and was mostly below the plausible global range for bamboos(32–256 Mg ha^(-1)).The sympatric distribution of multiple bamboo species at the study sites may have suppressed the AGB in four of the five studied species.The aboveground NPP estimates were between 3.43 and 14.25 Mg ha^(-1) yr^(-1);those for D.membranaceus(8.20 Mg ha^(-1) yr^(-1))and I.sinica(14.25 Mg ha^(-1) yr^(-1))were comparable to mean global estimates for temperate evergreen forests(8.78 Mg ha^(-1) yr^(-1))and tropical moist forests(10.56 Mg ha^(-1) yr^(-1)).High culm recruitment rates(15.20–23.39%yr^(-1))were major contributors to aboveground NPP estimates.Seasonal patterns of aboveground NPP were largely influenced by the phenology of the new culms.In the four sympodial bamboo species,new culms began to emerge following the onset of persistent rainfall,mainly in July and August.However,the sprouting of new culms in the monopodial species I.sinica followed a trend of increasing temperatures,mainly in March and April.Thus,our results indicate that bamboos have considerable potential for sequestering carbon in northern Laos,but that this potential may be affected by climate change.

Economic Benefit Analysis of Carbon Sequestration of Five Typical Forest Types in BeijingMiyun Watershed

This study provides basis information for estimating the feasibility of the environmental and ecological forestry construction project in the area. Through the survey in Miyun watershed, the economical benefits of carbon sequestration in five typical forest types have been studied by calculating the biomass from the timber accumulation data and converting to the money value. The results show that: in the duration of 100 years, at a discount rate of 5%, and 197 RMB yuan/t as the price of the carbon sequestration, the present value (PV) of the carbon sequestration in different forests are: 6900-9300 yuan/ha in Chinese pine forest,6100-8200 yuan/ha in oak forest, 4500-6100 yuan/ha in other broadleaf forests, 2300-3200 yuan/ha in shrubs and 1300-1800 yuan/ha in cypress forest. The annual mean economic benefit of carbon sequestration is 770-1040 yuan/ha. The pine forest has the highest carbon sequestration benefit, followed by oak forest, other broadleaf forest, shrubs, and cypress forest. If the land is suitable for all forests, pine forest and oak forest should be planted in order to sequestrate more carbon.