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1.
The effects of reforestation on carbon(C) sequestration in China′s Loess Plateau ecosystem have attracted much research attention in recent years. Black locust trees(Robinia pseudoacacia L.) are valued for their important use in reforestation and water and soil conservation efforts. This forest type is widespread across the Loess Plateau, and must be an essential component of any planning for C sequestration efforts in this fragile ecological region. The long-term effects of stand age on C accumulation and allocation after reforestation remains uncertain. We examined an age-sequence of black locust forest(5, 9, 20, 30, 38, and 56 yr since planting) on the Loess Plateau to evaluate C accumulation and allocation in plants(trees, shrubs, herbages, and leaf litter) and soil(0–100 cm). Allometric equations were developed for estimating the biomass of tree components(leaf, branch, stem without bark, bark and root) with a destructive sampling method. Our results demonstrated that black locust forest ecosystem accumulated C constantly, from 31.42 Mg C/ ha(1 Mg = 10~6 g) at 5 yr to 79.44 Mg C/ha at 38 yr. At the ′old forest′ stage(38 to 56 yr), the amount of C in plant biomass significantly decreased(from 45.32 to 34.52 Mg C/ha) due to the high mortality of trees. However, old forest was able to accumulate C continuously in soil(from 33.66 to 41.00 Mg C/ha). The C in shrub biomass increased with stand age, while the C stock in the herbage layer and leaf litter was age-independent. Reforestation resulted in C re-allocation in the forest soil. The topsoil(0–20 cm) C stock increased constantly with stand age. However, C storage in sub-top soil, in the 20–30, 30–50, 50–100, and 20–100 cm layers, was age-independent. These results suggest that succession, as a temporal factor, plays a key role in C accumulation and re-allocation in black locust forests and also in regional C dynamics in vegetation.  相似文献   

2.
Biomass carbon sequestration by planted forests in China   总被引：2，自引：1，他引：1  
The planted forest area and carbon sequestration have increased significantly in China, because of large-scale reforestation and afforestation in the past decades. In this study, we developed an age-based volume-to-biomass method to estimate the carbon storage by planted forests in China in the period of 1973–2003 based on the data from 1209 field plots and national forest inventories. The results show that the total carbon storage of planted forests was 0.7743 Pg C in 1999–2003, increased by 3.08 times since the early 1970s. The carbon density of planted forests varied from 10.6594 Mg/ha to 23.9760 Mg/ha and increased by 13.3166 Mg/ha from 1973–1976 to 1999–2003. Since the early 1970s, the planted forests in China have been always a carbon sink, and the annual rate of carbon sequestration was 0.0217 Pg C/yr. The carbon storage and densities of planted forests varied greatly in space and time. The carbon storage of Middle South China was in the lead in all regions, which accounted for 23%–36% of national carbon storage. While higher C densities (from 17.79 Mg/ha to 26.05 Mg/ha) were usually found in Northeast China. The planted forests in China potentially have a high carbon sequestration since a large part of them are becoming mature and afforestation continues to grow.  相似文献   

3.
By using field survey data from the sixth forest inventory of Jiangxi Province in 2003, the biomass and carbon storage for three studied species （Pinus massoniana, Cunninghamia lanceolata, and Pinus elliottii） were estimated in Taihe and Xingguo counties of Boyang Lake Basin, Jiangxi Province, China. The relationship between carbon density and forest age was analyzed by logistic equations. Spatio-temporal dynamics of forest biomass and carbon storage in 1985-2003 were also described. The results show that total stand area of the three forest species was 3.10 × 10^5 ha, total biomass 22.20 Tg, vegetation carbon storage 13.07 Tg C, and average carbon density 42.36 Mg C/ha in the study area in 2003. Carbon storage by forest type in descending order was： P. massoniana, C. lanceolata and P. elliottii. Carbon storage by forest age group in descending order was： middle stand, young stand, near-mature stand and mature stand. Carbon storage by plantation forests was 1.89 times higher than that by natural forests. Carbon density of the three species increased 8.58 Mg C/ha during the study period. The carbon density of Taihe County was higher in the east and west, and lower in the middle. The carbon density of Xingguo County was higher in the northeast and lower in the middle. In general, the carbon density increased with altitude and gradient. Afforestation projects contribute significantly to increasing stand area and carbon storage. Appropriate forest management may improve the carbon sequestration capacity of forest ecosystems.  相似文献   

4.
Three-North Shelterbelt Forest(TSF) program, is one of six key forestry programs and has a 73-year construction period, from 1978 to 2050. Quantitative analysis of the carbon sequestration of shrubs in this region is important for understanding the overall function of carbon sequestration of the forest and other terrestrial ecosystems in China. This study investigated the distribution area of shrubland in the TSF region based on remote sensing images in 1978 and 2008, and calculated the carbon density of shrubland in combination with the field investigation and previous data from published papers. The carbon sequestration quantity and rate from 1978 to 2008 was analyzed for four sub-regions and different types of shrubs in the TSF region. The results revealed that: 1) The area of shrubland in the study area and its four sub-regions increased during the past thirty years. The area of shrubland for the whole region in 2008 was 1.2 × 10~7 ha, 72.8% larger than that in 1978. The Inner Mongolia-Xinjiang Sub-region was the largest shrubland distribution area, while the highest coverage rate was found in the North China Sub-region. 2) In decreasing order of their carbon sequestration, the four types of shrubs considered in this study were Hippophae rhamnoides, Caragana spp., Haloxylon ammodendron and Vitex negundo var. heterophylla. The carbon sequestration of H. rhamnoides, with a maximum mean carbon density of 16.5 Mg C/ha, was significantly higher than that of the other three species. 3) The total carbon sequestration of shrubland in the study region was 4.5×10~7 Mg C with a mean annual carbon sequestration of 1.5 ×10~6 Mg C. The carbon density in the four sub-regions decreased in the following order: the Loess Plateau Sub-region, the North China Sub-region, the Northeast China Sub-region and the Inner Mongolia-Xinjiang Sub-region. The paucity of studies and data availability on the large-scale carbon sequestration of shrub species suggests this study provides a baseline reference for future research in this area.  相似文献   

5.
Afforestation and reforestation are effective and ecological ways of mitigating elevated atmospheric carbon dioxide(CO2) concentration and increasing carbon(C) storage in terrestrial ecosystems. In this study, we measured the above-ground(tree, herbaceous plants and litter) and below-ground(root and soil) C storage in an aspen plantation(Populus davidiana) monoculture(PD), a larch plantation(Larix pincipis-rupprechtii) monoculture(LP), a pine plantation(Pinus tabulaeformis) monoculture(PT), a larch and birch mixed plantation(L. pincipis-rupprechtii and Betula platyphlla mixed)(MLB), and an apricot plantation(Armeniaca sibirica) monoculture(AS) under the Desertification Combating Program in Hebei Province, the northern China. The objective was to assess the effect of afforestation species on ecosystem C pools of different plantation types. Results showed that C storage of LP stand(258.0 Mg/ha) and MLB(163.4 Mg/ha) were significantly higher than the C storage in PD(45.5 Mg/ha), PT(58.9 Mg/ha) and AS(49.4 Mg/ha), respectively. Soil C was the main carbon pool of the ecosystem C storage in the five plantation stands, ranging from 31.4 Mg/ha to 232.5 Mg/ha, which accounted for 69.0%–90.1% of the total ecosystem C storage. The C storage in tree layer was about 5.2%–23.2% of ecosystem C storage. The herbaceous plants and litter layers contained 1.0%–6.0% and 1.5%–3.3% of ecosystem C storage, respectively. Our results suggest that tree species should be incorporated to accurately develop regional C budget of afforestation program, and also imply that substantial differences in ecosystem C stocks among plantation types can facilitate decision making on C management.  相似文献   

6.
The raising concentration of atmospheric CO_2 resulted in global warming. The forest ecosystem in Tibet played an irreplaceable role in maintaining global carbon balance and mitigating climate change for its abundant original forest resources with powerful action of carbon sink. In the present study, the samples of soil and vegetation were collected at a total of 137 sites from 2001 to 2018 in Tibet. Based on the field survey of Tibet's forest resources and 8~(th) forest inventory data, we estimated the carbon storage and carbon density of forest vegetation(tree layer, shrub, grass, litter and dead wood) and soil(0-50 cm) in Tibet. Geostatistical methods combined with Kriging spatial interpolation and Moran's I were applied to reveal their spatial distribution patterns and variation characteristics. The carbon density of forest vegetation and soil in Tibet were 74.57 t ha~(-1) and 96.24 t ha~(-1), respectively. The carbon storage of forest vegetation and soil in Tibet were 344.35 Tg C and 440.53 Tg C, respectively. Carbon density of fir(Abies forest) was 144.80 t ha~(-1) with the highest value among all the forest types. Carbon storage of spruce(Picea forest) was the highest with 99.09 Tg C compared with other forest types. The carbon density of fir forest and spruce forest both increased with the rising temperature and precipitation. Temperature was the main influential factor. The spatial distribution of carbon density of forest vegetation, soil, and ecosystem in Tibet generally showed declining trends from western Tibet to eastern Tibet. Our results facilitated the understanding of the carbon sequestration role of forest ecosystem in the Tibet. It also implied that as the carbon storage potential of Tibet's forests are expected to increase, these forests are likely to serve as huge carbon sinks in the current era of global warming and climate change.  相似文献   

7.
The changes in soil organic carbon(C) mineralization as affected by anthropogenic disturbance directly determine the role of soils as C source or sink in the global C budget. The objectives of this study were to investigate the effects of anthropogenic disturbance(aquaculture pond, pollutant discharge and agricultural activity) on soil organic C mineralization under different water conditions in the Minjiang River estuary wetland, Southeast China. The results showed that the organic C mineralization in the wetland soils was significantly affected by human disturbance and water conditions(P 0.001), and the interaction between human disturbance activities and water conditions was also significant(P 0.01). The C mineralization rate and the cumulative mineralized carbon dioxide-carbon(CO_2-C)(at the 49th day) ranked from highest to lowest as follows: Phragmites australis wetland soil aquaculture pond sediment soil near the discharge outlet rice paddy soil. This indicated that human disturbance inhibited the mineralization of C in soils of the Minjiang River estuary wetland, and the inhibition increased with the intensity of human disturbance. The data for cumulative mineralized CO_2-C showed a good fit(R~2 0.91) to the first-order kinetic model C_t = C_0(1 – exp(–kt)). The kinetic parameters C_0, k and C_0 k were significantly affected by human disturbance and water conditions. In addition, the total amount of mineralized C(in 49 d) was positively related to C_0, C_0 k and electrical conductivity of soils. These findings indicated that anthropogenic disturbance suppressed the organic C mineralization potential in subtropical coastal wetland soils, and changes of water pattern as affected by human activities in the future would have a strong influence on C cycling in the subtropical estuarine wetlands.  相似文献   

8.
In karst regions,the spatial heterogeneity of soil mineral oxides and environmental variables is still not clear.We investigated the spatial heterogeneity of SiO2,Al2O3,Fe2O3,CaO,MgO,P2O5,K2O,and MnO contents in the soils of slope land,plantation forest,secondary forest,and primary forest,as well as their relationships with environmental variables in a karst region of Southwest China.Geostatistics,principal component analysis(PCA),and canonical correlation analysis(CCA)were applied to analyze the field data.The results show that SiO2was the predominant mineral in the soils(45.02%–67.33%),followed by Al2O3and Fe2O3.Most soil mineral oxide components had a strong spatial dependence,except for CaO,MgO,and P2O5in the plantation forest,MgO and P2O5in the secondary forest,and CaO in the slope land.Dimensionality reduction in PCA was not appropriate due to the strong spatial heterogeneity in the ecosystems.Soil mineral oxide components,the main factors in all ecosystems,had greater influences on vegetation than those of conventional soil properties.There were close relationships between soil mineral oxide components and vegetation,topography,and conventional soil properties.Mineral oxide components affected species diversity,organic matter and nitrogen levels.  相似文献   

9.
Woody debris (WD) is an important part of natural Pinus tabulaeformis mixed stands, and it affects the forest ecosystem stability and development. The WD spatial patterns are especially important structural characteristics that can provide insights into forest dynamics. In this paper, the WD storage, WD spatial patterns and WD associations among the main species were examined in the natural secondary forest on Loess Plateau in northwest China. Data were collected in a 1 ha (100 m × 100 m) permanent plot, and all the trees with a diameter at breast height of more than 3 cm were measured and stem-mapped. Ripley’s K functions from the spatial-point-pattern-analysis method were used to analyze the spatial distribution and associations. The results showed that: (1) The total storage of WD was 10.73 t/ha, fallen wood was the main source of WD, and the majority diameters were greater than 20 cm, and in intermediate levels of decay; (2) The overall spatial pattern was closely related to the spatial scale, which exhibited an aggregated pattern on a small scale, and a random pattern on a large scale. The spatial patterns of coarse woody debris also gradually transitioned from an aggregated pattern in fine scales to a random pattern in broader spatial scales, which matched the overall spatial pattern. The spatial intensity was gradually decreased with the increasing diameters, and increased with the decomposition classes; (3) The WD of Pinus tabulaeformis species was negatively associated with Betula platyphylla and Populus davidiana on a small scale but positively associated with these species on a large scale. The spatial pattern and interspecies relations were the results of long-term interactions between the natural secondary forest community and the surrounding natural environment. These findings would provide a scientific basis for the sustainable management and protection of natural secondary forest ecosystems on Loess Plateau.  相似文献   

10.
Soil respiration (SR) is the second-largest flux in ecosystem carbon cycling. Due to the large spatio-temporal variability of environmental factors, SR varied among different vegetation types, thereby impeding accurate estimation of CO2 emissions via SR. However, studies on spatio-temporal variation of SR are still scarce for semi-arid regions of North China. In this study, we conducted 12-month SR measurements in six land-use types, including two secondary forests (Populus tomentosa (PT) and Robinia pseudoacacia (RP)), three artificial plantations (Armeniaca sibirica (AS), Punica granatum (PG) and Ziziphus jujuba (ZJ)) and one natural grassland (GR), to quantify spatio-temporal variation of SR and distinguish its controlling factors. Results indicated that SR exhibited distinct seasonal patterns for the six sites. Soil respiration peaked in August 2012 and bottomed in April 2013. The temporal coefficient of variation (CV) of SR for the six sites ranged from 76.98% to 94.08%, while the spatial CV of SR ranged from 20.28% to 72.97% across the 12-month measurement. Soil temperature and soil moisture were the major controlling factors of temporal variation of SR in the six sites, while spatial variation in SR was mainly caused by the differences in soil total nitrogen (STN), soil organic carbon (SOC), net photosynthesis rate, and fine root biomass. Our results show that the annual average SR and Q10 (temperature sensitivity of soil respiration) values tended to decrease from secondary forests and grassland to plantations, indicating that the conversion of natural ecosystems to man-made ecosystems may reduce CO2 emissions and SR temperature sensitivity. Due to the high spatio-temporal variation of SR in our study area, care should be taken when converting secondary forests and grassland to plantations from the point view of accurately quantifying CO2 emissions via SR at regional scales.  相似文献   

11.
Understanding the effects of simulated warming on photosynthetic performance of aquatic plants may provide strong supports for predicting future dynamics of wetland ecosystems in the context of climate change. The plateau wetlands located in Yunnan province are highly sensitive to climate warming due to their high altitude and cold temperature. Here, we conducted a temperaturecontrolled experiment using two temperature manipulations (ambient temperature as the control and 2°C higher than ambient temperature as the warmed treatment) to determine the photosynthetic characteristics of two lakeside dominant species (Scirpus validus Vahl and Typha orientalis C. Presl.) in Dianchi Lake. Net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), and transpiration rate of S. validus that grew under warmed treatment were all significantly higher than those under the control. Gs and Ci of T. orientalis showed similar patterns as S. validus did. For the response curves of Pn to photosynthetic active radiation (Pn-PAR) and intercellular CO2 concentration (Pn-Ci), S. validus had higher Pn values under elevated temperatures than the control, while Pn-PAR and Pn-Ci curves of T. orientalis did not separate clearly under two temperature scenarios. Both S. validus and T. orientalis had higher maximum net photosynthetic rate, light saturation point, dark respiration rate, the maximum rate of RuBP carboxylation (Vcmax), maximum electron transport rate driving RuBP regeneration (Jmax), the ratio of Vcmax to Jmax, triosephosphate utilization, and 1, 5-bishosphate carboxylase ribulose content under warmed treatment than those under the control. This study provides a preliminary step for predicting the future primary production and vegetation dynamics of plateau wetlands in Yunnan province.  相似文献   

12.
It is critical to study how different forest management practices affect forest carbon sequestration under global climate change regime. Previous researches focused on the stand-level forest carbon sequestration with rare investigation of forest carbon stocks influ- enced by forest management practices and climate change at regional scale. In this study, a general integrative approach was used to simulate spatial and temporal variations of woody biomass and harvested biomass of forest in China during the 21st century under dif- ferent scenarios of climate and CO2 concentration changes and management tasks by coupling Integrated Terrestrial Ecosystem Carbon budget （InTEC） model with Global Forest Model （G4M）. The results showed that forest management practices have more predominant effects on forest stem stocking biomass than climate and CO2 concentration change. Meanwhile, the concurrent future changes in cli- mate and CO2 concentration will enhance the amounts of stem stocking biomass in forests of China by 12%-23% during 2001-2100 relative to that with climate change only. The task for maximizing stem stocking biomass will dramatically enhance the stem stocking biomass from 2001~100, while the task for maximum average increment will result in an increment of stem stocking biomass before 2050 then decline. The difference of woody biomass responding to forest management tasks was owing to the current age structure of forests in China. Meanwhile, the sensitivity of long-term woody biomass to management practices for different forest types （coniferous forest, mixed forest and deciduous forest） under changing climate and CO2 concentration was also analyzed. In addition, longer rotation length under future climate change and rising CO2 concentration scenario will dramatically increase the woody biomass of China during 2001~100. Therefore, our estimation indicated that taking the role of forest management in the carbon cycle into the consideration at regional or national level is very important to project the forest carbon sequestration under future climate change and rising atmospheric CO2 concentration.  相似文献   

13.
Changes in the fungal and bacterial biomass and community structure in litter after the volcanic eruptions of Mount Usu, northern Japan were investigated using a chronosequence approach, which is widely used for analyzing vegetation succession. The vegetation changed from bare ground(10 years after the eruptions) with little plant cover and poor soil to monotonic grassland dominated by Polygonum sachalinense with undeveloped soil(33 years) and then to deciduous broad-leaved forest dominated by Populus maximowiczii with diverse species composition and well-developed soil(100 years). At three chronosequential sites, we evaluated the compositions of phospholipid fatty acids(PLFAs), carbon(C) and nitrogen(N) contents and the isotope ratios of C(δ13C) and N(δ15N) in the litter of two dominant species, Polygonum sachalinense and Populus maximowiczii. The C/N ratio, δ13C and δ15N in the litter of these two species were higher in the forest than that in the bare ground and grassland. The PLFAs gradually increased from the bare ground to the forest, showing that microbial biomass increased with the development of the soil and/or vegetation. The fungi-to-bacteria ratio of PLFA was constant at 5.3 ± 1.4 in all three sites, suggesting that fungi were predominant. A canonical correspondence analysis suggested that the PLFA composition was related tothe successional ages and the developing soil properties(P 0.05, ANOSIM). The chronosequential analysis effectively detected the successional changes in both microbial and plant communities.  相似文献   

14.
Soil seed banks can act as a potential seed source for natural revegetation and restoration. However, in a saline-alkaline grassland, it remains unclear how the stages of vegetation succession affect the characteristics of soil seed banks and the potential of soil seed banks of different successional stages for vegetation restoration. In this study, seasonal changes of the soil seed bank, and seed production and dispersal dynamics along degradation successional gradients were investigated in a saline-alkaline grassland in Northeast China, where the dominant grass during the 1960 s, Leymus chinensis was replaced with the secondary successional order of Puccinellia chinampoensis, Chloris virgata, and Suaeda salsa, together with bare patches. It was found that the soil seed bank composition varied according to the changing vegetation and had the highest species richness(7–16) in the climax successional stage, but had a low S?rensen similarity(0.22–0.37) with the aboveground vegetation. There was a high seed density of the soil seed bank(21 062–62 166/m2 in August and December) and also high S?rensen similarity index values(0.47–0.60) in the secondary successional stages of P. chinampoensis, C. virgata, and S. salsa. In bare patches, there were many seeds in the soil seed bank and some seedlings also appeared in the aboveground vegetation, indicating the existence of a persistent soil seed bank. Seed density and species richness differed substantially among the different successional stages, which was related to the reproductive characteristics of the standing plants in vegetation communities. Due to the lack of propagules of perennial species, especially the climax species of L. chinensis, in the soil, the successful restoration of the degraded saline-alkaline grassland was not possible. The study proved that in a degraded saline-alkaline grassland dominated by biennial or annual species, the soil seed bank was important for the revegetation of the current dominant plants, but not for the restoration of the original target species. Therefore, it is necessary to induce seeds or other propagules of the target perennial species.  相似文献   

15.
Land use change is one of the major factors that affect soil organic carbon(SOC) variation and global carbon balance. However, the effects of land use change on SOC are always variable. In this study, using a series of paired-field experiments, we estimated the effects of revegetation types and environmental conditions on SOC stock and vertical distribution after replacement of cropland with poplar(Populus tomentosa) and korshinsk peashrub(Caragana korshinskii) in three climate regions(Chifeng City, Fengning City and Datong City of the ′Beijing-Tianjin Sandstorm Source Control′(BTSSC) program area. The results show that SOC sequestration rate ranges from 0.15 Mg/(ha·yr) to 3.76 Mg/(ha·yr) in the soil layer of 0–100 cm in early stage after cropland afforestation in the BTSSC program area. The SOC accumulation rates are the highest in Fengning for both the two vegetation types. Compared to C. korshinskii, P. tomentosa has greater effects on SOC accumulation in the three climate regions, but significantly greater effect only appears in Datong. The SOC density increases by 20%–111% and 15%–59% for P. tomentosa and 9%–63% and 0–73% for C. korshinskii in the 0–20 cm and 20–100 cm soil layers, respectively. Our results indicate that cropland afforestation not only affects SOC stock in the topsoil, but also has some effects on subsoil carbon. However, the effect of cropland afforestation on SOC accumulation varied with climate regions and revegetation types. Considering the large area of revegetation and relatively high SOC accumulation rate, SOC sequestration in the BTSSC program should contribute significantly to decrease the CO2 concentration in the atmosphere.  相似文献   

16.
Carbon sequestration occurs when cultivated soils are re-vegetated. In the hilly area of the Loess Plateau, China, black locust(Robinia pseudoacacia) plantation forest and grassland were the two main vegetation types used to mitigate soil and water loss after cultivation abandonment. The purpose of this study was to compare the soil carbon stock and flux of these two types of vegetation which restored for 25 years. The experiment was conducted in Yangjuangou catchment in Yan′an City, Shaanxi Province, China. Two adjacent slopes were chosen for this study. Six sample sites were spaced every 35–45 m from summit to toe slope along the hill slope, and each sample site contained three sampling plots. Soil organic carbon and related physicochemical properties in the surface soil layer(0–10 cm and 10–20 cm) were measured based on soil sampling and laboratory analysis, and the soil carbon dioxide(CO2) emissions and environmental factors were measured in the same sample sites simultaneously. Results indicated that in general, a higher soil carbon stock was found in the black locust plantation forest than that in grassland throughout the hill slope. Meanwhile, significant differences in the soil carbon stock were observed between these two vegetation types in the upper slope at soil depth 0–10 cm and lower slope at soil depth 10–20 cm. The average daily values of the soil CO2 emissions were 1.27 μmol/(m2·s) and 1.39 μmol/(m2·s) for forest and grassland, respectively. The soil carbon flux in forest covered areas was higher in spring and less variation was detected between different seasons, while the highest carbon flux was found in grassland in summer, which was about three times higher than that in autumn and spring. From the carbon sequestration point of view, black locust plantation forest on hill slopes might be better than grassland because of a higher soil carbon stock and lower carbon flux.  相似文献   

17.
The Beijing-Tianjin Sand Source Control Project(BTSSCP), a national ecological restoration project, was launched to construct an ecological protection system in the Beijing-Tianjin sand source areas to reduce dust hazards. The carbon sequestration dynamics can be used to assess the ecological effects of an ecological restoration project. Here, we conducted vegetation and soil study to assess the carbon sequestration in the plantations with 10 years old stands in Beijing-Tianjin sand source areas. The results at the site scales indicated that the average net increase of plantation ecosystem carbon stock was 33.8 Mg C ha~(-1), with an annual increase rate of 3.38 Mg C ha~(-1) yr~(-1). The average net increase of carbon varied among regions, vegetation types, and forest management activities. Soil bulk density in the top soil decreased slightly after 10-year implementation of the project. Coniferous forests and shrubs are suitable plant species for sand source areas.Natural restoration in the plantations is a practical and feasible and promising approach for enhancing ecosystem carbon sequestration potential.  相似文献   

18.
Soil organic carbon (SOC) was considered to be a key index in evaluation of soil degradation and soil C sequestration. To discuss the spatial-temporal dynamics of SOC in arable layer in reversed desertification area, a case study was conducted in Yulin City, Shaanxi Province, China. Data of SOC were based on general soil survey in 1982 and repeated soil sampling in 2003. Soil organic carbon content (SOCC) was determined by K2Cr3O2-FeSO4 titration method, and soil organic carbon density (SOCD) was calculated by arithmetic average and area weighted average method, respectively. On average, SOCC and SOCD of the arable layer in the study area from 1982 to 2003 had increased 0.5 Ig/kg and 0.16kg/m2, respectively. Considering main soil types, the widest distributed Arid-Sandic Entisols had lowest values and increments of SOCC and SOCD during the study period; while the second widest Los-Orthic Entisols had higher values and increments of SOCC and SOCD, compared to the mean values of the whole region. The results indicated that reversed desertification process was due to the modification of land use and management practices, such as natural vegetation recovery, planting grass, turning arable land to grassland, and soil and water conservation etc., which can improve SOCC and SOCD and thus enhance soil C sequestration.  相似文献   

19.
Soil microorganisms are sensitive indicator of soil health and quality. Understanding the effects of vegetation biomass and seasonal change on soil microorganisms is vital to evaluate the soil quality and implement vegetation restoration. This study analyzed the soil phospholipid fatty acids (PLFAs) in fresh and withered Kudzu (Pueraria montana var. lobata) vegetation conditions in different seasons. The results showed that vegetation biomass and seasonal change significantly affected microbial biomass and its community structure. Both fresh and withered Kudzu cover significantly increased soil microbial biomass, and the growth effect of microbes in the soil with fresh Kudzu cover was more obvious than that with withered Kudzu cover. Compared with the dry season, the rainy season significantly increased the microbial biomass and the B/F (the ratio of bacterial to fungal PLFAs) ratio but dramatically reduced the G+/G- (the ratio of gram-positive to gram-negative bacteria PLFAs). Kudzu cover and seasonal change had a significant effect on microbial structure in soil covered by higher vegetation biomass. Furthermore, soil temperature and moisture had different correlations with specific microbial biomass in the two seasons. Our findings highlight the effect of Kudzu vine cover on the soil microenvironment and soil microhabitat, enhancing the soil quality in the Dry-hot Valley of Jinsha River, Southwest China.  相似文献   

20.
Energy crops are a basic material in the bioenergy industry, and they can also mitigate carbon emissions and have environmental benefits when planted on marginal lands. The aim of this study was to evaluate the potential productivity of energy crops on marginal lands in China. A mechanistic model, combined with energy crop and land use characteristics, and meteorological and soil parameters, was used to simulate the potential productivity of energy crops. There were three main results. 1) The total marginal land in China was determined to be 104.78 × 10~6 ha. The 400-mm precipitation boundary line, which is the dividing line between the semi-humid and semi-arid zones in China, also divided the marginal land into shrub land and sparse forest land in the southeast and bare land, bare rock land, and saline alkali land in the northeast. 2) The total area of the marginal land suitable for planting energy crops was determined to be 55.82 × 10~6 ha, with Xanthoceras sorbifolia and Cerasus humilis mainly grown in the northern China, Jatropha curcas and Cornus wilsoniana mainly grown in the southwest and southeast, and Pistacia chinensis mainly grown in the central area, while also having a northeast-southwest zonal distribution. 3) Taking the highest yield in overlapping areas, the potential productivity of target energy crops was determined to be 32.63 × 10~6 t/yr. Without considering the overlapping areas, the potential productivity was 6.81 × 10~6 t/yr from X. sorbifolia, 8.86 × 10~6 t/yr from C. humilis, 7.18 × 10~6 t/yr from J. curcas, 9.55 × 10~6 t/yr from P. chinensis, and 7.78 × 10~6 t/yr from C. wilsoniana.  相似文献   

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