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1.
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.  相似文献   

2.
Subtropical evergreen broad-leaved forest is the most widely distributed land-cover type in eastern China. As the rate of land-use change accelerates worldwide, it is becoming increasingly important to quantify ecosystem biomass and carbon (C) and nitrogen (N) pools. Above and below-ground biomass and ecosystem pools of N and C in a subtropical secondary forest were investigated at Laoshan Mountain Natural Reserve, eastern China. Total biomass was 142.9 Mg ha−1 for a young stand (18 years) and 421.9 Mg ha−1 for a premature stand (ca. 60 years); of this, root biomass was from 26.9 (18.8% of the total) to 100.3 Mg ha−1 (23.8%). Total biomass C and N pools were, respectively, 71.4 Mg ha−1 and 641.6 kg ha−1 in the young stand, and 217.0 Mg ha−1 and 1387.4 kg ha−1 in the premature stand. The tree layer comprised 91.8 and 89.4% of the total biomass C and N pools in the young stand, and 98.0 and 95.6% in the premature stand. Total ecosystem C and N pools were, respectively, 101.4 and 4.6 Mg ha−1 for the young stand, and 260.2 and 6.6 Mg ha−1 for the premature stand. Soil C comprised 23.8–29.6% of total ecosystem C whereas soil N comprised 76.9–84.4% of the total. Our results suggest that a very high percentage of N in this subtropical forest ecosystem is stored in the mineral soil, whereas the proportion of organic C in the soil pool is more variable. The subtropical forest in eastern China seems to rapidly accumulate biomass during secondary succession, which makes it a potentially rapid accumulator of, and large sink for, atmospheric C.  相似文献   

3.
Tropical tree plantations may play an important role in mitigating CO2 emissions through their potential to capture and sequester carbon from the atmosphere. The Clean Development Mechanism (CDM) as well as voluntary initiatives provide economic incentives for afforestation and reforestation efforts through the generation and sale of carbon credits. The objectives of our study were to measure the carbon (C) storage potential of 1, 2 and 10-years old Tectona grandis plantations in the province of Chiriquí, Western Panama and to calculate the monetary value of aboveground C storage if sold as Certified Emission Reduction (CER) carbon credits. The average aboveground C storage ranged from 2.9 Mg C ha−1 in the 1-year-old plantations to 40.7 Mg C ha−1 in the 10-year-old plantations. Using regression analysis we estimated the potential aboveground C storage of the teak plantation over a 20 year rotation period. The CO2-storage over this period amounted to 191.1 Mg CO2 ha−1. The discounted revenues that could be obtained by issuance of carbon credits during a 20 year rotation period were about US$460 for temporary CER and US$560 for long-term CER, and thus, contribute to a minor extent (1%) to overall revenues, only.  相似文献   

4.
Land-use and land cover strongly influence carbon (C) storage and distribution within ecosystems. We studied the effects of land-use on: (i) above- and belowground biomass C, (ii) soil organic C (SOC) in bulk soil, coarse- (250–2000 μm), medium- (53–250 μm) and fine-size fractions (<53 μm), and (iii) 13C and 15N abundance in plant litter, bulk soil, coarse-, and medium- and fine-size fractions in the 0–50 cm soil layer in Linaria AB, Canada between May and October of 2006. Five adjacent land-uses were sampled: (i) agriculture since 1930s, (ii) 2-year-old hybrid poplar (Populusdeltoides × Populus × petrowskyana var. Walker) plantation, (iii) 9-year-old Walker hybrid poplar plantation, (iv) grassland since 1997, and (v) an 80-year-old native aspen (Populus tremuloides Michx.) stand. Total ecosystem C stock in the native aspen stand (223 Mg C ha−1) was similar to that of the 9-year-old hybrid poplar plantation (174 Mg C ha−1) but was significantly greater than in the agriculture (132 Mg C ha−1), 2-year-old hybrid poplar plantation (110 Mg C ha−1), and grassland (121 Mg C ha−1). Differences in ecosystem C stocks between the land-uses were primarily the result of different plant biomass as SOC in the 0–50 cm soil layer was unaffected by land-use change. The general trend for C stocks in soil particle-size fractions decreased in the order of: fine > medium > coarse for all land-uses, except in the native aspen stand where C was uniformly distributed among soil particle-size fractions. The C stock in the coarse-size fraction was most affected by land-use change whilst the fine fractions the least. Enrichment of the natural abundances of 13C and 15N across the land-uses since time of disturbance, i.e., from agriculture to 2- and then 9-year-old hybrid poplar plantations or to grassland, suggests shifts from more labile forms of C to more humified forms of C following those land-use changes.  相似文献   

5.

Pinus plantations have increased in Brazil, and native forest areas have been converted for timber production. The clearing and the long-term loblolly pine (Pinus taeda L.) land-use effects on soil carbon and nitrogen stocks were evaluated in a natural broadleaved forest and in loblolly pine sites cultivated for 29, 35, 38 and 49 years, as well the soil contribution as ecosystem carbon pool. According to the exponential-decay model fitted to changes in carbon stock, the initial soil carbon stock of 200 Mg ha?1 to a depth of 100 cm in the natural forest decreased by 36% over 49 years of pine cultivation (around 72.4 Mg ha?1 of C). Around two-thirds of this decrease occurred in the top 30 cm of the soil and intensively in the first 12 years of cultivation, but slowly faded as carbon stock tended to reach a new steady state after approximately 49 years of cultivation. The soil nitrogen stock in the natural forest was 14.2 Mg ha?1 to a depth of 100 cm and decreased by 36% over the 49 years. This decrease was linear according to the fitted model, especially in the top 30 cm where nitrogen decline was 83% and was proportionally more intense than the carbon decline. Despite the soil carbon decrease, soil remained the largest carbon reservoir in the ecosystem for the growing rotation time of loblolly pine in this region.

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6.
The poplar based agroforestry system improves aggregation of soil through huge amounts of organic matter in the form of leaf biomass. The extent of improvement may be affected by the age of the poplar trees and the soil type. The surface and subsurface soil samples from agroforestry and adjoining non-agroforestry sites with different years of poplar plantation (1, 3 and 6 years) and varying soil textures (loamy sand and sandy clay) were analyzed for soil organic carbon, its sequestration and aggregate size distribution. The average soil organic carbon increased from 0.36 in sole crop to 0.66% in agroforestry soils. The increase was higher in loamy sand than sandy clay. The soil organic carbon increased with increase in tree age. The soils under agroforestry had 2.9–4.8 Mg ha−1 higher soil organic carbon than in sole crop. The poplar trees could sequester higher soil organic carbon in 0–30 cm profile during the first year of their plantation (6.07 Mg ha−1 year−1) than the subsequent years (1.95–2.63 Mg ha−1 year−1). The sandy clay could sequester higher carbon (2.85 Mg ha−1 year−1) than in loamy sand (2.32 Mg ha−1 year−1). The mean weight diameter (MWD) of soil aggregates increased by 3.2, 7.3 and 13.3 times in soils with 1, 3 and 6 years plantation, respectively from that in sole crop. The increase in MWD with agroforestry was higher in loamy sand than sandy clay soil. The water stable aggregates (WSA >0.25 mm) increased by 14.4, 32.6 and 56.9 times in soils with 1, 3 and 6 years plantation, respectively, from that in sole crop. The WSA >0.25 mm were 6.02 times higher in loamy sand and 2.2 times in sandy clay than in sole crop soils.  相似文献   

7.
The distribution of fine (<2 mm diameter) and small roots (2–20 mm diameter) was investigated in a chronosequence consisting of 9-year-old, 26-year-old, 82-year-old and 146-year-old European beech (Fagus sylvatica) stands. A combination of trench wall observations and destructive root sampling was used to establish whether root distribution and total biomass of fine and small roots varied with stand age. Root density decreased with soil depth in all stands, and variability appeared to be highest in subsoil horizons, especially where compacted soil layers occurred. Roots clustered in patches in the top 0–50 cm of the soil or were present as root channels at greater depths. Cluster number, cluster size and number of root channels were comparable in all stands, and high values of soil exploitation occurred throughout the entire chronosequence. Overall fine root biomass at depths of 0–120 cm ranged from 7.4 Mg ha−1 to 9.8 Mg ha−1, being highest in the two youngest stands. Small root biomass ranged from 3.6 Mg ha−1 to 13.3 Mg ha−1. Use of trench wall observations combined with destructive root samples reduced the variability of these estimates. These records showed that variability in fine root distribution depended more on soil depth and edaphic conditions than on stand age, and suggest that trench wall studies provide a useful tool to improve estimates of fine root biomass.  相似文献   

8.
Hurricanes cause abrupt carbon reduction in forests, but silviculture treatment can be an effective means of quickly regenerating and restoring hurricane-damaged sites. This study assessed how silviculture treatments affect carbon balance after hurricane damage in central Hokkaido, Japan. We examined carbon storage in trees and underground vegetation as well as carbon emissions from silviculture operations in 25-year-old stands, where scarification and plantation occurred just after hurricane damage. The amount of carbon stored varied according to silviculture treatment. Among three scarification treatments, a scarified depth of 0 cm (understory vegetation removal) led to the largest amount of carbon stored (64.7 t·ha-1 C). Among four plantation treatments, the largest amount of carbon was stored in a Larix hybrid (L. gmelinii var. japonica × L. kaempferi) plantation (80.3 t·ha-1 C). The plantation of Abies sachalinensis was not successful at accumulating carbon (40.5·ha-1 C). The amount of carbon emitted from silviculture operations was 0.05-0.14 t·ha-1 C, and it marginally affected the net carbon balance of the silviculture project. Results indicate that silviculture treatments should beperformed in an appropriate way to effectively recover the ability of carbon sequestration in hurricane-damaged forests.  相似文献   

9.
This study was conducted to determine carbon (C) dynamics following forest tending works (FTW) which are one of the most important forest management activities conducted by Korean forest police and managers. We measured organic C storage (above- and below-ground biomass C, forest floor C, and soil C at 50 cm depth), soil environmental factors (soil CO2 efflux, soil temperature, soil water content, soil pH, and soil organic C concentration), and organic C input and output (litterfall and litter decomposition rates) for one year in FTW and non-FTW (control) stands of approximately 40-year-old red pine (Pinus densiflora S. et Z.) forests in the Hwangmaesan Soopkakkugi model forest in Sancheonggun, Gyeongsangnam-do, Korea. This forest was thinned in 2005 as a representative FTW practice. The total C stored in tree biomass was significantly lower (P < 0.05) in the FTW stand (40.17 Mg C ha−1) than in the control stand (64.52 Mg C ha−1). However, C storage of forest floor and soil layers measured at four different depths was not changed by FTW, except for that at the surface soil depth (0–10 cm). The organic C input due to litterfall and output due to needle litter decomposition were both significantly lower in the FTW stand than in the control stand (2.02 Mg C ha−1 year−1 vs. 2.80 Mg C ha−1 year−1 and 308 g C kg−1 year−1 vs. 364 g C kg−1 year−1, respectively, both P < 0.05). Soil environmental factors were significantly affected (P < 0.05) by FTW, except for soil CO2 efflux rates and organic C concentration at soil depth of 0–20 cm. The mean annual soil CO2 efflux rates were the same in the FTW (0.24 g CO2 m−2 h−1) and control (0.24 g CO2 m−2 h−1) stands despite monthly variations of soil CO2 efflux over the one-year study period. The mean soil organic C concentration at a soil depth of 0–20 cm was lower in the FTW stand (81.3 g kg−1) than in the control stand (86.4 g kg−1) but the difference was not significant (P > 0.05). In contrast, the mean soil temperature was significantly higher, the mean soil water content was significantly lower, and the soil pH was significantly higher in the FTW stand than in the control stand (10.34 °C vs. 8.98 °C, 48.2% vs. 56.4%, and pH 4.83 vs. pH 4.60, respectively, all P < 0.05). These results indicated that FTW can influence tree biomass C dynamics, organic C input and output, and soil environmental factors such as soil temperature, soil water content and soil pH, while soil C dynamics such as soil CO2 efflux rates and soil organic C concentration were little affected by FTW in a red pine stand.  相似文献   

10.
Root biomass and root distribution were studied in Entisols derived from the thick deposition of volcanic pumice on Hokkaido Island, Japan, to examine the effect of soil conditions on tree root development. The soil had a thin (<10 cm) A horizon and thick coarse pumiceous gravel layers with low levels of available nutrients and water. Two stands were studied: a Picea glehnii–Abies sachalinensis stand (PA stand) and a Larix kaempferi–Betula platyphylla var. japonica stand (LB stand). The allometric relationships between diameter at breast height (DBH) and aboveground and belowground biomass of these species were obtained to estimate stand biomass. The belowground biomass was small: 30.6 Mg ha−1 for the PA stand and 24.3 Mg ha−1 for the LB stand. The trunk/root ratios of study stands were 4.8 for the PA stand and 4.3 for the LB stand, which were higher than those from previous studies in boreal and temperate forests. All species developed shallow root systems, and fine roots were spread densely in the shallow A horizon, suggesting that physical obstruction by the pumiceous layers and their low levels of available water and nutrients restricted downward root elongation. The high trunk/root ratios of the trees may also have resulted from the limited available rooting space in the study sites.  相似文献   

11.
Determining the magnitude of carbon (C) storage in forests and peatlands is an important step towards predicting how regional carbon balance will respond to climate change. However, spatial heterogeneity of dominant forest and peatland cover types can inhibit accurate C storage estimates. We evaluated ecosystem C pools and productivity in the Marcell Experimental Forest (MEF), in northern Minnesota, USA, using a network of plots that were evenly spaced across a heterogeneous 1-km2 mosaic composed of a mix of upland forests and peatlands. Using a nested plot design, we estimated the standing C stock of vegetation, coarse detrital wood and soil pools. We also estimated aboveground net primary production (ANPP) as well as coarse root production. Additionally we evaluated how vegetation cover types within the study area differed in C storage. The total ecosystem C pool did not vary significantly among upland areas dominated by aspen (160 ± 13 Mg C ha−1), mixed hardwoods (153 ± 19 Mg C ha−1), and conifers (197 ± 23 Mg C ha−1). Live vegetation accounted for approximately 50% of the total ecosystem C pool in these upland areas, and soil (including forest floor) accounted for another 35–40%, with remaining C stored as detrital wood. Compared to upland areas, total C stored in peatlands was much greater, 1286 ± 125 Mg C ha−1, with 90–99% of that C found in peat soils that ranged from 1 to 5 m in depth. Forested areas ranged from 2.6 to 2.9 Mg C ha−1 in ANPP, which was highest in conifer-dominated upland areas. In alder-dominated and black spruce-dominated peatland areas, ANPP averaged 2.8 Mg C ha−1, and in open peatlands, ANPP averaged 1.5 Mg C ha−1. In treed areas of forest and peatlands, our estimates of coarse root production ranged from 0.1 to 0.2 Mg C ha−1. Despite the lower production in open peatlands, all peatlands have acted as long-term C sinks over hundreds to thousands of years and store significantly more C per unit area than is stored in uplands. Despite occupying only 13% of our study area, peatlands store almost 50% of the C contained within it. Because C storage in peatlands depends largely on climatic drivers, the impact of climate changes on peatlands may have important ramifications for C budgets of the western Great Lakes region.  相似文献   

12.
The above- and belowground biomass and nutrient content (N, P, K, Ca, S and Mg) of pure deciduous Nothofagus antarctica (Forster f.) Oersted stands grown in a marginal site and aged from 8 to 180 years were measured in Southern Patagonia. The total biomass accumulated ranged from 60.8 to 70.8 Mg ha−1 for regeneration and final growth stand, respectively. The proportions of belowground components were 51.6, 47.2, 43.9 and 46.7% for regeneration, initial growth, final growth and mature stand, respectively. Also, crown classes affected the biomass accumulation where dominant trees had 38.4 Mg ha−1 and suppressed trees 2.6 Mg ha−1 to the stand biomass in mature stand. Nutrient concentrations varied according to tree component, crown class and stand age. Total nutrient concentration graded in the fallowing order: leaves > bark > middle roots > small branches > fine roots > sapwood > coarse roots > heartwood. While N and K concentrations increased with age in leaves and fine roots, concentration of Ca increased with stand age in all components. Dominant trees had higher N, K and Ca concentrations in leaves, and higher P, K and S concentrations in roots, compared with suppressed trees. Although the stands had similar biomass at different ages, there were important differences in nutrient accumulation per hectare from 979.8 kg ha−1 at the initial growth phase to 665.5 kg ha−1 at mature stands. Nutrient storage for mature and final growth stands was in the order Ca > N > K > P > Mg > S, and for regeneration stand was Ca > N > K > Mg > P > S. Belowground biomass represented an important budget of all nutrients. At early ages, N, K, S, Ca and Mg were about 50% in the belowground components. However, P was 60% in belowground biomass and then increased to 70% in mature stands. These data can assist to quantify the impact of different silviculture practices which should aim to leave material (mainly leaves, small branches and bark) on the site to ameliorate nutrient removal and to avoid a decline of long-term yields.  相似文献   

13.
Nitrogen (N) deposition exceeds the critical loads for this element in most parts of Switzerland apart from the Alps. At 17 sites (8 broadleaved stands, 8 coniferous stands, and 1 mixed stand) of the Swiss Long-term Forest Ecosystem Research network, we are investigating whether N deposition is associated with the N status of the forest ecosystems. N deposition, assessed from throughfall measurements, was related to the following indicators: (1) nitrate leaching below the rooting zone (measured on a subset of 9 sites); (2) the N nutrition of the forest stand based on foliar analyses (16 sites); and (3) crown defoliation, a non specific indicator of tree vitality (all 17 sites). Nitrate leaching ranging from about 2 to 16 kg N ha−1 a−1 was observed at sites subjected to moderate to high total N deposition (>10 kg ha−1 a−1). The C/N ratio of the soil organic layer, or, when it was not present, of the upper 5 cm of the mineral soil, together with the pool of organic carbon in the soil, played a critical role, as previous studies have also found. In addition, the humus type may need to be considered as well. For instance, little nitrate leaching (<2 kg N ha−1 a−1) was recorded at the Novaggio site, which is subjected to high total N deposition (>30 kg ha−1 a−1) but characterized by a C/N ratio of 24, large organic C stocks, and a moder humus type. Foliar N concentrations correlated with N deposition in both broadleaved and coniferous stands. In half of the coniferous stands, foliar N concentrations were in the deficiency range. Crown defoliation tended to be negatively correlated with N concentrations in the needles. In the majority of the broadleaved stands, foliar N concentrations were in the optimum nutritional range or, on one beech plot with high total N deposition (>25 kg ha−1 a−1), above the optimum values. There was no correlation between the crown defoliation of broadleaved trees and foliar concentrations.  相似文献   

14.
Data on the biomass and productivity of southeast Asian tropical forests are rare, making it difficult to evaluate the role of these forest ecosystems in the global carbon cycle and the effects of increasing deforestation rates in this region. In particular, more precise information on size and dynamics of the root system is needed. In six natural forest stands at pre-montane elevation (c. 1000 m a.s.l.) on Sulawesi (Indonesia), we determined above-ground biomass and the distribution of fine (d < 2 mm) and coarse roots (d > 2 mm), estimated above- and below-ground net production, and compared the results to literature data from other pre-montane paleo- and neotropical forests. The mean total biomass of the stands was 303 Mg ha−1 (or 128 Mg C ha−1), with the largest biomass fraction being recorded for the above-ground components (286 Mg ha−1) and 11.2 and 5.6 Mg ha−1 of coarse and fine root biomass (down to 300 cm in the soil profile), resulting in a remarkably high shoot:root ratio of c. 17. Fine root density in the soil profile showed an exponential decrease with soil depth that was closely related to the concentrations of base cations, soil pH and in particular of total P and N. The above-ground biomass of these stands was found to be much higher than that of pre-montane forests in the Neotropics, on average, but lower compared to other pre-montane forests in the Paleotropics, in particular when compared with dipterocarp forests in Malesia. The total above- and below-ground net primary production was estimated at 15.2 Mg ha−1 yr−1 (or 6.7 Mg C ha−1 yr−1) with 14% of this stand total being invested below-ground and 86% representing above-ground net primary production. Leaf production was found to exceed net primary production of stem wood. The estimated above-ground production was high in relation to the mean calculated for pre-montane forests on a global scale, but it was markedly lower compared to data on dipterocarp forests in South-east Asia. We conclude that the studied forest plots on Sulawesi follow the general trend of higher biomasses and productivity found for paleotropical pre-montane forest compared to neotropical ones. However, biomass stocks and productivity appear to be lower in these Fagaceae-rich forests on Sulawesi than in dipterocarp forests of Malesia.  相似文献   

15.
Land management practices that simultaneously improve soil properties are crucial to high crop production and minimize detrimental impact on the environment. We examined the effects of crop residues on crop performance, the fluxes of soil N2O and CO2 under wheat-maize (WM) and/or faba bean-maize (FM) rotations in Amorpha fruticosa (A) and Vetiveria zizanioides (V) intercropping systems on a loamy clay soil, in subtropical China. Crop performance, soil N2O and CO2 as well as some potential factors such as soil water content, soil carbon, soil nitrogen, microbial biomass and N mineralization were recorded during 2006 maize crop cultivation. Soil N2O and CO2 fluxes are determined using a closed-based chamber. Maize yield was greater after faba bean than after wheat may be due to differences in supply of N from residues. The presence of hedgerow significantly improved maize grain yields. N2O emissions from soils with maize were considerably greater after faba bean (345 g N2O–N ha−1) than after wheat (289 g N2O–N ha−1). However, the cumulated N2O emissions did not differ significantly between WM and FM. The difference in N2O emissions between WM and FM was mostly due to the amounts of crop residues. Hedgerow alley cropping tended to emit more N2O than WM and FM, in particular A. fruticosa intercropping systems. Over the entire 118 days of measurement, the N2O fluxes represented 534 g N2O–N ha−1 (AWM) and 512 g N2O–N ha−1 (AFM) under A. fruticosa species, 403 g N2O–N ha−1 (VWM) and 423 g N2O–N ha−1 (VFM) under Vetiver grass. We observed significantly higher CO2 emission in AFM (5,335 kg CO2–C ha−1) from June to October, whereas no significant difference was observed among WM (3,480 kg CO2–C ha−1), FM (3,302 kg CO2–C ha−1), AWM (3,877 kg CO2–C ha−1), VWM (3,124 kg CO2–C ha−1) and VFM (3,309 kg CO2–C ha−1), indicating the importance of A. fruticosa along with faba bean residue on CO2 fluxes. As a result, crop residues and land conversion from agricultural to agroforestry can, in turn, influence microbial biomass, N mineralization, soil C and N content, which can further alter the magnitude of crop growth, soil N2O and CO2 emissions in the present environmental conditions.  相似文献   

16.
Generic or default values to account for biomass and carbon accumulation in tropical forest ecosystems are generally recognized as a major source of errors, making site and species specific data the best way to achieve precise and reliable estimates. The objective of our study was to determine carbon in various components (leaves, branches, stems, structural roots and soil) of single-species plantations of Vochysia guatemalensis and Hieronyma alchorneoides from 0 to 16 years of age. Carbon fraction in the biomass, mean (±standard deviation), for the different pools varied between 38.5 and 49.7% (±3 and 3.8). Accumulated carbon in the biomass increased with the plantation age, with mean annual increments of 7.1 and 5.3 Mg ha−1 year−1 for forest plantations of V. guatemalensis and H. alchorneoides, respectively. At all ages, 66.3% (±10.6) of total biomass was found within the aboveground tree components, while 18.6% (±20.9) was found in structural roots. The soil (0–30 cm) contained 62.2 (±13) and 71.5% (±17.1) of the total carbon (biomass plus soil) under V. guatemalensis and H. alchorneoides, respectively. Mean annual increment for carbon in the soil was 1.7 and 1.3 Mg ha−1 year−1 in V. guatemalensis and H. alchorneoides. Allometric equations were constructed to estimate total biomass and carbon in the biomass which had an R 2aj (adjusted R square) greater than 94.5%. Finally, we compare our results to those that could have resulted from the use of default values, showing how site and species specific data contribute to the overall goal of improving carbon estimates and providing a more reliable account of the mitigation potential of forestry activities on climate change.  相似文献   

17.
Long-term management impacts on carbon storage in Lake States forests   总被引：2，自引：0，他引：2  
We examined carbon storage following 50+ years of forest management in two long-term silvicultural studies in red pine and northern hardwood ecosystems of North America’s Great Lakes region. The studies contrasted various thinning intensities (red pine) or selection cuttings, shelterwoods, and diameter-limit cuttings (northern hardwoods) to unmanaged controls of similar ages, providing a unique opportunity to evaluate long-term management impacts on carbon pools in two major North American forest types. Management resulted in total ecosystem carbon pools of 130-137 Mg ha−1 in thinned red pine and 96-177 Mg ha−1 in managed northern hardwoods compared to 195 Mg ha−1 in unmanaged red pine and 224 Mg ha−1 in unmanaged northern hardwoods. Managed stands had smaller tree and deadwood pools than unmanaged stands in both ecosystems, but management had limited impacts on understory, forest floor, and soil carbon pools. Total carbon storage and storage in individual pools varied little across thinning intensities in red pine. In northern hardwoods, selection cuttings stored more carbon than the diameter-limit treatment, and selection cuttings generally had larger tree carbon pools than the shelterwood or diameter-limit treatments. The proportion of total ecosystem carbon stored in mineral soil tended to increase with increasing treatment intensity in both ecosystems, while the proportion of total ecosystem carbon stored in the tree layer typically decreased with increasing treatment intensity. When carbon storage in harvested wood products was added to total ecosystem carbon, selection cuttings and unmanaged stands stored similar levels of carbon in northern hardwoods, but carbon storage in unmanaged stands was higher than that of thinned stands for red pine even after adding harvested wood product carbon to total ecosystem carbon. Our results indicate long-term management decreased on-site carbon storage in red pine and northern hardwood ecosystems, but thinning intensity had little impact on carbon storage in red pine while increasing management intensity greatly reduced carbon storage in northern hardwoods. These findings suggest thinning to produce different stand structures would have limited impacts on carbon storage in red pine, but selection cuttings likely offer the best carbon management options in northern hardwoods.  相似文献   

18.
The importance of agroforestry systems in CO2 mitigation has become recognized worldwide in recent years. However, little is known about carbon (C) sequestered in poplar intercropping systems. The main objective of this study is to compare the effects of three poplar intercropping designs (configuration A: 250 trees ha−1; configuration B: 167 trees ha−1 and configuration C: 94 trees ha−1) and two intercropping systems (wheat–corn cropping system and wheat–soybean cropping system) on biomass production and C stocks in poplar intercropping systems. The experiment was conducted at Suqian Ecological Demonstration Garden of fast-growing poplar plantations in northwestern Jiangsu. A significant difference in C concentration was observed among the poplar biomass components investigated (P ≤ 0.05), with the highest value in stemwood and the lowest in fine roots, ranging from 459.9 to 526.7 g kg−1. There was also a significant difference in C concentration among the different crop components (P ≤ 0.05), and the highest concentration was observed in the corn ear. Over the 5-year period, the total poplar biomass increased with increasing tree density, ranging from 8.77 to 15.12 t ha−1, while annual biomass production among the crops ranged from 4.69 to 16.58 t ha−1 in the three configurations. Overall, total C stock in the poplar intercropping system was affected by configurations and cropping systems, and configuration A obtained the largest total C stock, reaching 16.7 t C ha−1 for the wheat–soybean cropping system and 18.9 t C ha−1 for the wheat–corn cropping system. Results from this case study suggest that configuration A was a relative optimum poplar intercropping system both for economic benefits and for C sequestration.  相似文献   

19.
Biomass of a mature man-made forest in West Java, Indonesia, was estimated to evaluate the carbon sequestration potential of plantation forest in the humid tropics. Twenty plots, each 0.25 ha in area and containing one to six planted species over 40 years of age and with closed canopies, were selected. Trunk dry mass was estimated from trunk diameter, tree height, and bulk density. Maximum trunk diameter (122 cm) was observed in a 46-year-old Khaya grandifoliola C. DC. tree, and the tallest tree (51 m) was a 46-year-old Shorea selanica (DC.) Blume. The largest trunk biomass (911 Mg ha−1) was achieved in the plot composed of two Khaya spp. Among the plots composed of indigeneous Dipterocarpaceae species, the largest trunk biomass was 635 Mg ha−1. These trunk biomasses were larger than those reported from primary rainforests in Southeast Asia (e.g., 403 Mg ha−1 in East Kalimantan, 522 and 368 Mg ha−1 in Peninsular Malaysia). The large biomass in this forest suggests that, given favorable conditions, man-made forests can accumulate the quantities of atmospheric carbon that were lost by the logging of primary forests in the humid tropics.  相似文献   

20.
This study examined the hypothesis that incorporation of Gliricidia sepium (Jacq.) Walp.) (gliricidia), a fast-growing, nitrogen-fixing tree, into agroforestry systems in southern Malawi may be used to increase the input of organic fertilizer and reduce the need for expensive inorganic fertilizers. The productivity of maize (Zea mays L.), pigeonpea (Cajanus cajan L.) and gliricidia grown as sole stands or in mixed cropping systems was examined at Makoka Research Station (latitude 15° 30′ S, longitude 35° 15′ E) and a nearby farm site at Nazombe between 1996 and 2000. Treatments included gliricidia intercropped with maize, with or without pigeonpea, and sole stands of gliricidia, maize and pigeonpea. Trees in the agroforestry systems were pruned before and during the cropping season to provide green leaf manure. Maize yields and biomass production by each component were determined and fractional light interception was measured during the reproductive stage of maize. Substantial quantities of green leaf manure (2.4 to 9.0 Mg ha−1 year−1) were produced from the second or third year after tree establishment. Green leaf manure and fuelwood production were greatest when gliricidia was grown as unpruned sole woodlots (c. 8.0 and 22 Mg ha−1 year−1 respectively). Improvements in maize yield in the tree-based systems also became significant in the third year, when c. 3.0 Mg ha−1 of grain was obtained. Tree-based cropping systems were most productive and exhibited greater fractional light interception (c. 0.6 to 0.7) than cropping systems without trees (0.1 to 0.4). No beneficial influence of pigeonpea on maize performance was apparent either in the presence or absence of gliricidia at either site in most seasons. However, as unpruned gliricidia provided the greatest interception of incident solar radiation (>0.9), coppicing may be required to reduce shading when gliricidia is grown together with maize. As pigeonpea production was unaffected by the presence of gliricidia, agroforestry systems containing gliricidia might be used to replace traditional maize + pigeonpea systems in southern Malawi. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

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