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1.
The purpose of this study was to compare carbon sequestration between moso bamboo (Phyllostachys heterocycla) and China fir (Cunninghamia lanceolata) forests. The study site was located in the lower mountain area of central Taiwan, where both moso bamboo and China fir were rich. In addition, moso bamboo and China fir forests were surveyed on 12 and 19 plantations, respectively. We predicted carbon sequestration based on the allometric model for moso bamboo and China fir forests and compared the relationships between characteristics of bamboo forests and elevation. The results showed that mean diameter at breast height (DBH), culms per hectare and aboveground biomass were not clearly affected by elevation, whereas a negative correlation (R = −0.600, p = 0.039) between mean DBH and stand density was found for moso bamboo forests. Moreover, the aboveground carbon storage was higher for China fir forests than for moso bamboo (99.5 vs. 40.6 Mg ha−1). However, moso bamboo is an uneven-aged stand which is only composed of 1-5-year-old culms, while China fir is an even-aged stand and the age range is from 15 to 54 years, such that, per year, the mean aboveground carbon sequestration is 8.13 ± 2.15 and 3.35 ± 2.02 Mg ha−1 for moso bamboo and China fir, respectively. On the other hand, the mean carbon sequestration of China fir decreases with increasing the age class. Furthermore, the ratio of moso bamboo to China fir is 2.39 and a T-test showed that the aboveground carbon levels were significantly different between these two species; thus, moso bamboo is a species with high potential for carbon sequestration.  相似文献   

2.
The efficiency with which trees convert photosynthetically active radiation (PAR) to biomass has been shown to be consistent within stands of an individual species, which is useful for estimating biomass production and carbon accumulation. However, radiation use efficiency (?) has rarely been measured in mixed-species forests, and it is unclear how species diversity may affect the consistency of ?, particularly across environmental gradients. We compared aboveground net primary productivity (ANPP), intercepted photosynthetically active solar radiation (IPAR), and radiation use efficiency (? = ANPP/IPAR) between a mixed deciduous forest and a 50-year-old white pine (Pinus strobus L.) plantation in the southern Appalachian Mountains. Average ANPP was similar in the deciduous forest (11.5 Mg ha−1 y−1) and pine plantation (10.2 Mg ha−1 y−1), while ? was significantly greater in the deciduous forest (1.25 g MJ−1) than in the white pine plantation (0.63 g MJ−1). Our results demonstrate that late-secondary hardwood forests can attain similar ANPP as mature P. strobus plantations in the southern Appalachians, despite substantially less annual IPAR and mineral-nitrogen availability, suggesting greater resource-use efficiency and potential for long-term carbon accumulation in biomass. Along a 260 m elevation gradient within each forest there was not significant variation in ?. Radiation use efficiency may be stable for specific forest types across a range of environmental conditions in the southern Appalachian Mountains, and thus useful for generating estimates of ANPP at the scale of individual watersheds.  相似文献   

3.
Efforts are needed in order to increase confidence for carbon accounts in the land use sector, especially in tropical forest ecosystems that often need to turn to default values given the lack of precise and reliable site specific data to quantify their carbon sequestration and storage capacity. The aim of this study was then to estimate biomass and carbon accumulation in young secondary forests, from 4 and up to 20 years of age, as well as its distribution among the different pools (tree including roots, herbaceous understory, dead wood, litter and soil), in humid tropical forests of Costa Rica. Carbon fraction for the different pools and tree components (stem, branches, leaves and roots) was estimated and varies between 37.3% (±3.3) and 50.3% (±2.9). Average carbon content in the soil was 4.1% (±2.1). Average forest plant biomass was 82.2 (±47.9) Mg ha−1 and the mean annual increment for carbon in the biomass was 4.2 Mg ha−1 yr−1. Approximately 65.2% of total biomass was found in the aboveground tree components, while 14.2% was found in structural roots and the rest in the herbaceous vegetation and necromass. Carbon in the soil increased by 1.1 Mg ha−1 yr−1. Total stored carbon in the forest was 180.4 Mg ha−1 at the age of 20 years. In these forests, most of the carbon (51-83%) was stored in the soil. Models selected to estimate biomass and carbon in trees as predicted by basal area had R2 adjustments above 95%. Results from this study were then compared with those obtained for a variety of secondary and primary forests in different Latin-American tropical ecosystems and in tree plantations in the same study area.  相似文献   

4.
Above- and belowground biomass in a Brazilian Cerrado   总被引：1，自引：0，他引：1  
Cerrado is a biome that occupies about 25% of the Brazilian territory and is characterized by a gradient of grassland to savanna and forest formations and by high species richness. It has been severely affected by degradation and deforestation and has been heavily fragmented over the past 4-5 decades. Despite the recognized overall ecological importance of the Cerrado, there are only few studies focusing on the quantification of biomass in this biome. We conducted such a case study in the South-East of Brazil in a cerrado sensu stricto (cerrado s.s.) with the goal to produce estimates of above- and belowground biomass and to develop allometric equations. A number of 120 trees from 18 species were destructively sampled and partitioned into the components: leaves, branches and bole. Five models with DBH (D), height (H), D2H and wood density (WD) as independent variables were tested for the development of allometric models for individual tree aboveground biomass (leaves + branches + bole). One model based on basal area (BA) as a stand parameter was also tested as an alternative approach for predicting aboveground biomass in the stand level. Belowground biomass was estimated by subsampling on 10 sample plots. Mean aboveground tree biomass (bole, branches and leaves) was estimated to be 62,965.5 kg ha−1(SE = 14.6%) and belowground biomass accounted for 37,501.8 kg ha−1 (SE = 23%). The best-fit equation for the estimation of individual tree aboveground biomass include DBH and wood density as explanatory variables (R2 = 0.898; SEE = 0.371) and is applicable for the diameter range of this study (5.0-27.6 cm) and in environments with similar conditions of the cerrado s.s. sampled. In the stand level, the model tested presented a higher goodness of fit than the single tree models (R2 = 0.934; SEE = 0.224). Our estimates of aboveground biomass are higher than reported by other studies developed in the same physiognomy, but the estimates of belowground biomass are within the range of values reported in other studies from sites in cerrado s.s. Both biomass estimates, however, exhibit relatively large standard errors. The root-to-shoot ratio of the sample trees is in the magnitude of reported values for savanna ecosystems, but smaller than estimated from other studies in the cerrado s.s.  相似文献   

5.
In regions of Australia of low–medium rainfall (500–800 mm/year), there is growing community and land-owner support for re-planting trees to achieve multiple environmental objectives, particularly amelioration of soil salinity. Sequestration of carbon by newly established trees is not only another important environmental benefit, but also a potential commercial benefit. To obtain estimates of carbon sequestered by species of commercial potential in such regions, we calibrated the carbon (C) accounting model FullCAM to Eucalyptus cladocalyx and Corymbia maculata plantations. This was achieved by harvesting trees of a range in sizes to determine the allometric relationships that most accurately predict biomass and stem density from measures of stem diameter. Predictions of stem diameter were obtained from a forest growth model (3-PG) previously calibrated for these two species. By applying these predictions of changes in stem diameter as the stand matures in our allometric relationships, we estimated changes in partitioning of biomass (between stem, branches, bark, foliage and roots) and stem wood density as the stand matures under scenarios of 500, 600 and 750 mm mean annual rainfall. We found that for both species, regardless of annual rainfall, throughout the rotation 37–50% of carbon sequestered in the total tree biomass was in the stem, 18–27% in both branches and roots, and the remainder in foliage or bark. However, rate of accumulation of carbon was dependent on annual rainfall, with average annual rate of sequestration of carbon in tree biomass and litter during the first rotation of E. cladocalyx (or C. maculata) increasing from 3.68 (or 4.17) to 4.72 (or 4.86) Mg C ha−1 yr−1 as annual rainfall increased from about 500 to 750 mm. Although it was predicted that decomposition negated any accumulation of debris between successive rotations, carbon was predicted to accumulate in sawlog products, given that assumed rates of product decomposition were slightly less than their rate of accumulation. This resulted in a slight increase (<8 Mg C ha−1) in predicted total sequestration of carbon between successive rotations.  相似文献   

6.
Allometric equations were developed and applied to forest inventory data to estimate biomass and carbon stocks for temperate species and forests of Durango and Chihuahua and for tropical dry forests of Sinaloa, Mexico. A total of 872 trees were harvested and dissected into their component parts: leaves and branches, boles, and coarse roots. Coarse roots of 40 temperate trees ranging in diameter at breast height (DBH) from 6.0 to 52.9 cm were excavated in their entirety (i.e., >0.5 cm diameter). The species sampled (number of trees) in tropical dry forests (39) were Lysiloma divaricata (Jacq) Macbr. (10), Haematoxylon brasiletto Karst. (10), Cochlospermum vitifolium (Wild.) (5), Ceiba acuminata (S. Watson) Rose (5), Bursera penicillata (B. inopinnata) (5), and Jatropha angustifolia Mull. Arg. (4) and in temperate forests (833) were Quercus spp. (118) (Q. rugosa Neé, 15, Quercus sideroxylla Humb. & Bonpl, 51, Quercus spp., 52), Pinus herrerae Martinez 1940 (19), Pinus oocarpa Schiede ex Schlectendal 1838 (31), Pinus engelmannii Carriere 1854 (7), Psudotsuga menziesii (Mirb.) Franco (19), Pinus leiophylla Schiede ex Schlectendal et Chamisso 1831 (27), Pinus teocote Schiede ex Schlectendal et Chamisso (55), Pinus ayacahuite Ehrenb. ex Schltdl. (58), Pinus cooperi Blanco (48), Pinus durangensis Martinez 1942 (385), and Pinus arizonica Engelmann 1879 (66). Allometric equations having only DBH as an independent variable were developed for each component of each species. Since Pinus herrerae, Pinus engelmannii, Pinus oocarpa and Pseudotsuga menziensii had a small number of trees, an individual allometric equation was developed for these species. We used non-linear regression to fit parameters of the typical allometric power equation. The resulting 31 equations (10 species or groups of species, three biomass components; bole, branch and leaves, and total aerial; and the generalized equation for coarse roots) fit the data well and enable the user to predict biomass by component for each of the 10 different groups of species or each of six temperate species. A single allometric equation that incorporates the basic specific gravity for aboveground biomass of all temperate tree species also fit the data well, and this equation provides both the detail and the accuracy supplied by species-specific, plant-part-specific equations. Biomass equations coupled with forest inventory data for temperate (637 circular, 1/10 ha plots) and tropical dry forests (166 20 m × 20 m-quadrats) of northwestern Mexico predict a mean (confidence intervals) of 130 Mg ha−1 (4.2 Mg ha−1) and 73 Mg ha−1 (7.1 Mg ha−1) for total tree and total aboveground biomass, respectively. Large sample sizes and the economic and ecological importance of the species studied make this data set uniquely useful for biomass estimations and for understanding the inherent heterogeneity of tree structure in dynamic tropical and temperate environments of northwestern Mexico.  相似文献   

7.
Biomass and carbon sequestration rate of a young (four year old) mixed plantation of Dalbergia sissoo Roxb., Acacia catechu Willd., and Albizia lebbeck Benth. growing in Terai region (a level area of superabundant water) of central Himalaya was estimated. The plantation is seed sown in the rainy season of year 2004 and spread over an area of 44 ha. Allometric equations for both above and below ground components were developed for three tree species. The density of trees in the plantation was 1322 trees ha−1 The diameters of trees were below 10 cm. Five diameter classes were defined for D. sissoo and A. catechu and 3 for A. lebbeck. 5 trees were harvested in each diameter class. Individual tree allometry was exercised for developing the allometric equations relating tree component (low and above ground) biomass to d.b.h. Post analysis equations were highly significant (P > 0.001) for each component of all species. In the plantation Holoptelia integrifolia Roxb. (Family Ulmaceae) has been reduced to shrub form because of frost. Only the aboveground biomass of H. integrifolia and other shrubs were estimated by destructive harvesting method. Herbaceous forest floor biomass and leaf litter fall were also estimated. The total forest vegetation biomass was 10.86 Mg ha−1 in 2008 which increased to 19.49 Mg ha−1 in 2009. The forest is sequestering carbon at the rate of 4.32 Mg ha−1 yr−1.  相似文献   

8.
The growth, aboveground biomass production and nutrient accumulation in black alder (Alnus glutinosa (L.) Gaertn.), silver birch (Betula pendula Roth.) and Scots pine (Pinus sylvestris L.) plantations during 7 years after planting were investigated on reclaimed oil shale mining areas in Northeast Estonia with the aim to assess the suitability of the studied species for the reclamation of post-mining areas. The present study revealed changes in soil properties with increasing stand age. Soil pH and P concentration decreased and soil N concentration increased with stand age. The largest height and diameter of trees, aboveground biomass and current annual production occurred in the black alder stands. In the 7-year-old stands the aboveground biomass of black alder (2100 trees ha−1) was 2563 kg ha−1, in silver birch (1017 trees ha−1) and Scots pine (3042 trees ha−1) stands respective figures were 161 and 1899 kg ha−1. The largest amounts of N, P, K accumulated in the aboveground part were in black alder stands. In the 7th year, the amount of N accumulated in the aboveground biomass of black alder stand was 36.1 kg ha−1, the amounts of P and K were 3.0 and 8.8 kg ha−1, respectively. The larger amounts of nutrients in black alder plantations are related to the larger biomass of stands. The studied species used N and P with different efficiency for the production of a unit of biomass. Black alder and silver birch needed more N and P for biomass production, and Scots pine used nutrients most efficiently. The present study showed that during 7 years after planting, the survival and productivity of black alder were high. Therefore black alder is a promising tree species for the reclamation of oil shale post-mining areas.  相似文献   

9.
Estimation of accurate biomass of different forest components is important to estimate their contribution to total carbon stock. There is lack of allometric equations for biomass estimation of woody species at sapling stage in tropical dry forest (TDF), and therefore, the carbon stored in this forest component is ignored. We harvested 46 woody species at sapling stage in a TDF and developed regression models for the biomass estimation of foliage, branch, bole and the total aboveground part. For foliage and branch biomass, the models with only stem diameter as estimator showed greater R 2. For bole and aboveground biomass, the models including wood specific gravity or wood density exhibited higher R 2 than those without wood density. Also, the model consisting of wood density, stem diameter and height had the lowest standard error of estimate for bole and aboveground biomass. Moreover, the R 2 values are very similar among models for each component. The measurement error of height and the use of a standard value of wood density together may introduce more than 2 % error into the models. Therefore, we suggest using diameter-only model, which may be more practical and equally accurate when applied to stands outside our study area.  相似文献   

10.
With increasing CO2 in the atmosphere, there is an urgent need of reliable estimates of biomass and carbon pools in tropical forests, most especially in Africa where there is a serious lack of data. Information on current annual increment (CAI) of carbon biomass resulting from direct field measurements is crucial in this context, to know how forest ecosystems will affect the carbon cycle and also to validate eddy covariance flux measurements. Biomass data were collected from 25 plots of 13 ha spread over the different vegetation types and land uses of a moist evergreen forest of 772,066 ha in Cameroon. With site-specific allometric equations, we estimated biomass and aboveground and belowground carbon pools. We used GIS technology to develop a carbon biomass map of our study area. The CAI was estimated using the growth rates obtained from tree rings analysis. The carbon biomass was on average 264 ± 48 Mg ha−1. This estimate includes aboveground carbon, root carbon and soil organic carbon down to 30 cm depth. This value varied from 231 ± 45 Mg ha−1 of carbon in Agro-Forests to 283 ± 51 Mg ha−1 of carbon in Managed Forests and to 278 ± 56 Mg ha−1 of carbon in National Park. The carbon CAI varied from 2.54 ± 0.65 Mg ha−1 year−1 in Agro-Forests to 2.79 ± 0.72 Mg ha−1 year−1 in Managed Forests and to 2.85 ± 0.72 Mg ha−1 year−1 in National Park. This study provides estimates of biomass, carbon pools and CAI of carbon biomass from a forest landscape in Cameroon as well as an appropriate methodology to estimate these components and the related uncertainty.  相似文献   

11.
The purpose of this study was to estimate biomass and carbon storage for a fast-growing makino bamboo (Phyllostachys makinoi). The study site was located in central Taiwan and the makino bamboo plantation had a stand density of 21191 ± 4107 culms ha−1. A diameter distribution model based on the Weibull distribution function and an allometric model was used to predict aboveground biomass and carbon storage. For an accurate estimation of carbon storage, the percent carbon content (PCC) in different sections of bamboo was determined by an elemental analyzer. The results showed that bamboos of all ages shared a similar trend, where culms displayed a carbon storage of 47.49–47.82%, branches 45.66–46.23%, and foliage 38.12–44.78%. In spite of the high density of the stand, the diameter distribution of makino bamboo approached a normal distribution and aboveground biomass and carbon storage were 105.33 and 49.81 Mg ha−1, respectively. Moreover, one-fifth of older culms from the entire stand were removed by selective cutting. If the distribution of the yield of older culms per year was similar to the current stand, the yields of biomass and carbon per year would be 21.07 and 9.89 Mg ha−1 year−1. An astonishing productivity was observed, where every 5 years the yield of biomass and carbon was equal to the current status of stockings. Thus, makino bamboo has a high potential as a species used for carbon storage.  相似文献   

12.
An accurate characterization of tree carbon (TC), forest floor carbon (FFC) and soil organic carbon (SOC) in tropical forest plantations is important to estimate their contribution to global carbon stocks. This information, however, is poor and fragmented. Carbon contents were assessed in patula pine (Pinus patula) and teak (Tectona grandis) stands in tropical forest plantations of different development stages in combination with inventory assessments and soil survey information. Growth models were used to associate TOC to tree normal diameter (D) with average basal area and total tree height (HT), with D and HT parameters that can be used in 6–26 years old patula pine and teak in commercial tropical forests as indicators of carbon stocks. The information was obtained from individual trees in different development stages in 54 patula pine plots and 42 teak plots. The obtained TC was 99.6 Mg ha−1 in patula pine and 85.7 Mg ha−1 in teak forests. FFC was 2.3 and 1.2 Mg ha−1, SOC in the surface layer (0–25 cm) was 92.6 and 35.8 Mg ha−1, 76.1 and 19 Mg ha−1 in deep layers (25–50 cm) in patula pine and teak, respectively. Carbon storage in trees was similar between patula pine and teak plantations, but patula pine had higher levels of forest floor carbon and soil organic carbon. Carbon storage in trees represents 37 and 60% of the total carbon content in patula pine and teak plantations, respectively. Even so, the remaining percentage corresponds to SOC, whereas FFC content is less than 1%. In summary, differences in carbon stocks between patula pine and teak trees were not significant, but the distribution of carbon differed between the plantation types. The low FFC does not explain the SOC stocks; however, current variability of SOC stocks could be related to variation in land use history.  相似文献   

13.
Carbon pools in two Quercus petraea (sessile oak) dominated chronosequences under different forest management (high forest and coppice with standards) were investigated. The objective was to study temporal carbon dynamics, in particular carbon sequestration in the soil and woody biomass production, in common forest management systems in eastern Austria along with stand development. The chronosequence approach was used to substitute time-for-space to enable coverage of a full rotation period in each system. Carbon content was determined in the following compartments: aboveground biomass, litter, soil to a depth of 50 cm, living root biomass and decomposing residues in the mineral soil horizons. Biomass carbon pools, except fine roots and residues, were estimated using species-specific allometric functions. Total carbon pools were on average 143 Mg ha−1 in the high forest stand (HF) and 213 Mg ha−1 in the coppice with standards stand (CS). The mean share of the total organic carbon pool (TOC) which is soil organic carbon (SOC) differs only marginally between HF (43.4%) and CS (42.1%), indicating the dominance of site factors, particularly climate, in controlling this ratio. While there was no significant change in O-layer and SOC stores over stand development, we found clear relationships between living biomass (aboveground and belowground) pools and C:N ratio in topsoil horizons with stand age. SOC pools seem to be very stable and an impact of silvicultural interventions was not detected with the applied method. Rapid decomposition and mineralization of litter, indicated by low O-horizon pools with wide C:N ratios of residual woody debris at the end of the vegetation period, suggests high rates of turnover in this fraction. CS, in contrast to HF benefits from rapid resprouting after coppicing and hence seems less vulnerable to conditions of low rainfall and drying topsoil.  相似文献   

14.
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   

15.
This paper presents a synthesis of experiments conducted in a tropical tree plantation established in 2001 and consisting of 22 plots of 45 m × 45 m with either one, three or six native tree species. We examined the changes in carbon (C) pools (trees, herbaceous vegetation, litter, coarse woody debris (CWD), and mineral topsoil at 0-10 cm depth) and fluxes (decomposition of CWD and litter, as well as soil respiration) both through time and among diversity levels. Between 2001 and 2009 the aboveground C pools increased, driven by trees. Across diversity levels, the mean observed aboveground C pool was 7.9 ± 2.5 Mg ha−1 in 2006 and 20.4 ± 7.4 Mg ha−1 in 2009, a 158% increase. There was no significant diversity effect on the observed aboveground C pool, but we found a significant decrease in the topsoil C pool, with a mean value of 34.5 ± 2.4 Mg ha−1 in 2001 and of 25.7 ± 5.7 Mg ha−1 in 2009 (F1,36 = 52.12, p < 0.001). Assuming that the biomass C pool in 2001 was negligible (<1 Mg ha−1), then the plantation gained in C, on average, ∼20 and lost ∼9 Mg ha−1 in biomass and soil respectively, for an overall gain of ∼11 Mg ha−1 over 8 years. Across the entire data set, we uncovered significant effects of diversity on CWD decomposition (diversity: F2,393 = 15.93, p < 0.001) and soil respiration (monocultures vs mixtures: t = 15.35, df = 11, p < 0.05) and a marginally significant time × diversity interaction on the loss of total C from the mineral topsoil pool (see above). Monthly CWD decomposition was significantly faster in monocultures (35.0 ± 24.1%) compared with triplets (31.3 ± 21.0%) and six-species mixtures (31.9 ± 26.8%), while soil respiration was higher in monocultures than in mixtures (t = 15.35, df = 11, p < 0.001). Path analyses showed that, as diversity increases, the links among the C pools and fluxes strengthen significantly. Our results demonstrate that tree diversity influences the processes governing the changes in C pools and fluxes following establishment of a tree plantation on a former pasture. We conclude that the choice of tree mixtures for afforestation in the tropics can have a marked influence on C pools and dynamics.  相似文献   

16.
Four forest stands each of twenty major forest types in sub-tropical to temperate zones (350 m asl–3100 m asl) of Garhwal Himalaya were studied. The aim of the study was to assess the stem density, tree diversity, biomass and carbon stocks in these forests and make recommendations for forest management based on priorities for biodiversity protection and carbon sequestration. Stem density ranged between 295 and 850 N ha−1, while total biomass ranged from 129 to 533 Mg ha−1. Total carbon storage ranged between 59 and 245 Mg ha−1. The range of Shannon–Wiener diversity index was between 0.28 and 1.75. Most of the conifer-dominated forest types had higher carbon storage than broadleaf-dominated forest types. Protecting conifer-dominated stands, especially those dominated by Abies pindrow and Cedrus deodara, would have the largest impact, per unit area, on reducing carbon emissions from deforestation.  相似文献   

17.
  • ? In the 1940s–1950s, large limba (Terminalia superba Engl. & Diels) plantations were established in the Democratic Republic of Congo to reduce the pressure on the natural forests.
  • ? The objective of this study was to evaluate the potential of these long-rotation plantations as production forests (timber) and carbon sinks.
  • ? Five different plantations, between 50 and 58 years old, were sampled. Over a sample surface of more than 73 ha, the diameter above buttresses of 2 680 trees, bole height of 265 trees and tree height of 128 trees was measured.
  • ? To estimate the commercial volume, a nonlinear power law regression was used (R 2 = 0.95). A power law variance function was applied to counter heteroscedasticity of the residual plot. Estimates of commercial tree and stand volume at 50 to 58 y were 5.6 ± 4.1 m3 and 183.9 ± 135.0 m3 ha?1. Stand volumes appear low but are explained by a large decrease in tree density. However, the mean volume increment of 3.2–3.7 m3 ha?1 y?1 corresponds well with teak plantations of a similar age. For limba, aboveground biomass and carbon estimates of this study (resp. 108.4 and 54.2 Mg ha?1) differ significantly from those of existing aboveground biomass models (resp. 135.7–143.9 Mg ha?1 biomass and 67.9–72.0 Mg ha?1 C). All aboveground biomass and carbon estimates for T. superba stands were lower than for the estimates of young fast-growing plantations like Tectona grandis L. f., Eucalyptus spp. and Acacia spp. (≤ 30 y).
    •   相似文献   

    18.
    Significant increases in aboveground biomass production have been observed when Eucalyptus is planted with a nitrogen-fixing species due to increased nutrient availability and more efficient use of light. Eucalyptus and Acacia are among the most popular globally planted genera with the area of Eucalyptus plantations alone expanding to over 19 Mha over the past two decades. Despite this, little is known about how nutrition and light availability in mixed-species tree plantations influence water use and water use efficiency (WUE). This study examined to what extent water use and WUE have been influenced by increased resource availability and growth in mixed-species plantations. Monocultures of Eucalyptus globulus Labill. and Acacia mearnsii de Wildeman and 1:1 mixtures of these species were planted. Growth and transpiration were measured between ages 14 and 15 years. Aboveground biomass increment (Mg ha−1) was significantly higher in mixtures (E. globulus; 4.8 + A. mearnsii; 0.9) than E. globulus (3.3) or A. mearnsii monocultures (1.6). Annual transpiration (mm) measured using the heat pulse technique was also higher in mixtures (E. globulus; 285 + A. mearnsii; 134) than in E. globulus (358) and A. mearnsii (217) monocultures. Mixtures exhibited higher WUE than monocultures due to significant increases in the WUE of E. globulus in mixtures (1.69 kg aboveground biomass per cubic metre water transpired) compared to monocultures (0.94). The differences in WUE appear to result from increases in canopy photosynthetic capacity and above- to belowground carbon allocation in mixtures compared to monocultures. Although further studies are required and operational issues need to be resolved, the results of this study suggest that mixed eucalypt–acacia plantations may be used in water-limited environments to produce a given amount of wood with less water than eucalypt monocultures. Alternatively, because mixtures can be more productive and use more water per unit land area (but use it more efficiently), they could be utilized in recharge zones where rising water tables and salinity result from the replacement of vegetation (fast growing trees) that uses higher quantities of water with vegetation (shallow rooted annual crops) that use lower quantities of water.  相似文献   

    19.
    We compared soil organic carbon (SOC) stocks and stability under two widely distributed tree species in the Mediterranean region: Scots pine (Pinus sylvestris L.) and Pyrenean oak (Quercus pyrenaica Willd.) at their ecotone. We hypothesised that soils under Scots pine store more SOC and that tree species composition controls the amount and biochemical composition of organic matter inputs, but does not influence physico-chemical stabilization of SOC. At three locations in Central Spain, we assessed SOC stocks in the forest floor and down to 50 cm in the mineral in pure and mixed stands of Pyrenean oak and Scots pine, as well as litterfall inputs over approximately 3 years at two sites. The relative SOC stability in the topsoil (0-10 cm) was determined through size-fractionation (53 μm) into mineral-associated and particulate organic matter and through KMnO4-reactive C and soil C:N ratio.Scots pine soils stored 95-140 Mg ha−1 of C (forest floor plus 50 cm mineral soil), roughly the double than Pyrenean oak soils (40-80 Mg ha−1 of C), with stocks closely correlated to litterfall rates. Differences were most pronounced in the forest floor and uppermost 10 cm of the mineral soil, but remained evident in the deeper layers. Biochemical indicators of soil organic matter suggested that biochemical recalcitrance of soil organic matter was higher under pine than under oak, contributing as well to a greater SOC storage under pine. Differences in SOC stocks between tree species were mainly due to the particulate organic matter (not associated to mineral particles). Forest conversion from Pyrenean oak to Scots pine may contribute to enhance soil C sequestration, but only in form of mineral-unprotected soil organic matter.  相似文献   

    20.
    Forest ecosystems play a significant role in sequestering carbon (C) in biomass and soils. Plantations established in subtropical China since the 1980s, mainly of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) in monocultures, have proved to be major C sinks. However, information is lacking about whether mixing Chinese fir with broadleaved tree species will increase stand growth and C sequestration. We address this question by comparing a pure Chinese fir plantation and two mixed plantations established in 1990 at Huitong Experimental Station of Forest Ecology, Hunan Province, China. The mixed plantations include Chinese fir and either Kalopanax septemlobus (Thunb.) Koidz or Alnus cremastogyne Burk., planted at 4:1 ratios. We found that total C storage was 123, 131 and 142 Mg ha−1 in the pure plantation, mixed plantation with K. septemlobus, and mixed plantation with A. cremastogyne, respectively. The mixed plantation with A. cremastogyne increased C storage in biomass relative to the pure Chinese fir plantation (P < 0.05). No significant difference was detected between mixed plantations. Soil C storage did not differ among these plantations, ranging from 67.9 ± 7.1 to 73.3 ± 9.1 Mg ha−1, which accounted for about 55% of the total C pools. Our results indicated that as the mixture of Chinese fir and broadleaved species will increase both biomass C and soil C storage over pure Chinese fir, and will do it, within 15 years of planting.  相似文献   

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