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1.
The distributions of boron in Japanese cedar (Cryptomeria japonica D. Don) sapwood blocks treated with aqueous or methanolic boric acid [B(OH)3] solutions were explored through Raman spectroscopy and prompt gamma-ray analysis (PGA). B(OH)3 was the sole boron species observed in Raman spectra of the wood blocks treated with either solution. Plots of weight gain of the treated wood blocks versus boron concentration in treatment solutions were found to be linear. The results indicated that the methanolic solution makes it possible to impregnate wood with much larger amounts of boron than the aqueous solution. PGA confirmed that B(OH)3 was highly enriched near the end grains of the treated wood blocks. Raman measurements suggested that boron content in the bulk of the wood block is not as large as expected from the weight gain of the treated wood blocks when an ordinary air-drying method is used. It was concluded that the aqueous solution impregnates the cell walls of wood with boron more easily than the methanolic solution. Part of this report was presented at the 55th (Kyoto, March 2005) and 56th (Akita, August 2006) Annual Meetings of the Japan Wood Research Society. This article follows the previous rapid communication “Analysis of boron in wood treated with boric acid solutions using Doppler broadening method of prompt gamma-rays.” J Wood Sci (2006) 52:279–281  相似文献   

2.
Test samples of Japanese larch (Larix leptolepis) heartwood and Japanese beech (Fagus crenata) sapwood were heated for 22 h at constant temperatures (50°–180°C) under three water content conditions. Raman spectra of the samples were recorded before and after the heat treatments, and spectral changes in the range from 1000 cm−1 to 1800 cm−1 were evaluated using the difference spectrum method. For both wood species, the Raman band intensity at 1655–1660 cm−1 due mainly to the C=C and C=O groups in lignin clearly decreased with increasing heat-treatment temperature (HTT). The spectral change was thought to reflect the progress of condensation reactions of lignin molecules during the heat treatment. Moreover, the decrease in band intensity was considerably facilitated by the presence of water in the cell wall, suggesting that the condensation is closely related to the softening of lignin. From the spectral changes in the wavenumber region of 1200–1500 cm−1, it was considered that wood constituents are partially decomposed at the higher HTT. Part of this article was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, March 2003  相似文献   

3.
 Raman spectra were measured for Japanese cedar wood and bark pyrolyzed in a nitrogen atmosphere at various temperatures (200°–1100°C). Two characteristic bands, near 1340 and 1590 cm−1, denoted as the D-band and G-band due to graphitic carbon, respectively, appeared on all the spectra; and the spectral features changed markedly with increasing heat-treatment temperature (HTT). The Raman parameters (band position, band width, D/G ratio) of the bands were deconvolved using of a curve-fitting method. There was no significant difference in the values of the parameters between the wood and bark. The D-band position and the G-band width showed a marked HTT dependence in the region of 400°–800°C. We described the correlations of the Raman parameters with HTT and investigated the availability of Raman spectroscopy as a means for evaluating HTT. Received: January 28, 2002 / Accepted: June 14, 2002  相似文献   

4.
The knowledge of the convective heat and mass transfer coefficients is required for the characterization of the boundary conditions of the heat and mass transfer equations of a wood drying model based on water potential. A new experimental method for the determination of the convective mass transfer coefficient is presented. This method is based on the measurement of the moisture content, and indirectly the water potential, at the surface of a wood specimen at different drying times. Drying experiments were performed on red pine (Pinus resinosa Ait.) sapwood from nearly saturated to dry conditions at 56 °C, 52% relative humidity and air velocities of 1.0, 2.5 and 5.0 m s−1. The results show that the convective mass transfer coefficient is constant until the wood surface moisture content reaches about 80% and then decreases more or less gradually as the moisture content decreases further. The convective mass transfer coefficient increases with air velocity. A regression analysis shows that there is no significant improvement in considering the water potential gradient near the wood surface when the difference in water potential between the surface and the surrounding air (ψs − ψ∞) is used to determine the convective mass flux at the surface. Also, ψs − ψ∞ is more appropriate than the water vapour pressure difference (pvs − pv∞) as the responsible driving force of the moisture flux leaving the wood surface. The convective heat transfer coefficient was determined during the same experiments. A plateau is observed at high values of moisture content corresponding to the constant drying rate period. Received 27 February 1998  相似文献   

5.
Multipurpose tree species （MPTs） were studied in an agroforestry arboretum under subtropical humid climate in Northeast India. Out of 12 MPTs planted under agroforestry systems, Acacia auriculiformis in spacing of 2 m × 2 m （2500 stems·hm^-2） could have the potentiality to meet the timber/fuelwood requirement due to its high wood production of 635 m^3·hm^-2 with mean annual increment （MAI） of 2.54×10^-2 m^3.treel.a^-1 in a short rotation period of 10 years. Thus, A. auriculiformis is a short rotation forest tree species suitable to grow in subtropical humid climate. On the other hand, at 16 years of age, Eucalyptus hybrid and Michelia champaca in spacing of 3 m × 3 m （1111 stems.hm^2） produced appreciably high timber volume of 315 m^3.hm^-2 and 165 m^3.hm^-2 with MAI of 1.77×10^-2 m^3.tree^-1·a^-1 and 0.92×10.2 m^3.tree^-1.a^-1, respectively. At 16 years of age, Gmelina arborea produced a timber volume of 147 m^3.hm^-2 with MAI of 1.47×10^-2 m^3.tree^-1.a^-1 followed by Samania saman （140 m^3.hm^-2）, Albizziaprocera （113 m^3·hm^-2） and Tectona grandis （79 m3.hm^-2） with MAI of 1.40, 1.13 and 0.78 × 10^-2 m^3 .tree^-1a^-1, respectively in 4 m × 4 m spacing （625 stems.hm^-2）. Gliricidia maculata and Leucaena leucocephala could be used as live fences around the farm boundary to supply their N-rich leaves for mulch as well as manure to crops. In agroforestry arboretum, direct seeded upland rice （Oryza sativa - variety, AR-11）, groundnut （Arachis hypogaea - variety, JL-24） and sesamum （Sesamum indicum - variety, B-67） were grown during the initial period upto 8 years of tree establishment. Under other MPTs, there was a reduction in crop productivity as compared to open space. After 8 years of tree establishment, horti-silvi and silvi-pastoral systems were developed and pineapple （Ananas comosus - variety Queen）, turmeric （Curcuma longa -variety RCT -1） and cowpea （Vigna sinensis - variety Pusa Barsati） as forage crop were raised. The productivity of p  相似文献   

6.
To investigate the potential effects of nitrogen (N) deposition on Japanese forests, a chronic N-addition experiment that included three treatments (HNO3, NH4NO3, and control) was carried out in a 20-year-old Japanese cedar (Cryptomeria japonica D. Don) stand in eastern Japan over 7 years. The amount of N applied was 168 kg N ha−1 year−1 on the HNO3 plots and 336 kg N ha−1 year−1 on the NH4NO3 plots. Tree growth, current needle N concentration, and soil solution chemistry were measured. Nitrogen application decreased the pH and increased NO3 −, Ca2+, Mg2+, and Al concentrations in the soil solution. The needle N concentration increased in both of the N plots during the first 3 years. Nevertheless, the annual increments in height and in the diameter at breast height of the Japanese cedars were not affected by N application, and no visible signs of stress were detected in the crowns. Our results suggest that young Japanese cedar trees are not deleteriously affected by an excess N load.  相似文献   

7.
从黑龙江省双城林场采集健康的分月扇舟蛾2龄幼虫,将室内保存一年的分月扇舟蛾虫尸研碎,分离提纯得到纯净的颗粒体病毒。将病毒悬液稀释为1..58×103PIB·mL-1,1.58×104PIB·mL-1,1.58×105PIB·mL-1,1.58×106PIB·mL-1,1.58×107PIB·mL-1,1.58×108PIB·mL-1,1.58×109PIB·mL-17种浓度,采集新鲜的杨树叶分别浸入上述不同浓度的悬液,对采集的健康幼虫进行接毒。9天实验结果表明,浓度为1..58×103PIB·mL-1时校正死亡率最小(7.32%),浓度是1.58×109PIB·mL-1时校正死亡率最大(97.36%),浓度对数和死亡几率值的回归直线方程为y=1.946 0.558x,LC50为2.97×105PIB·mL-1。1.58×105PIB·mL-1,1.58×106PIB·mL-1,1.58×107PIB·mL-1,1.58×108PIB·mL-1,1.58×109PIB·mL-1w所对应的半致死时间(LT50)分别为8.55d,6.89d,5.9d,4.65d,4.08d。随着浓度的增大,LT50逐渐缩短,说明该病毒的毒力较强,作为杀虫剂具有很好的应用潜力。  相似文献   

8.
The effect of strain on dry, clear Norway spruce (Picea abies [L.] Karst.) wood was studied by tensile testing along the cell axis and by in situ X-ray diffraction measurements. The mean microfibril angle (MFA) was initially 3–12 degrees and did not decrease due to strain. Based on the positions of the reflections 200 and 004 of crystalline cellulose, cellulose chains elongated and the distance between the hydrogen bonded sheets of chains decreased due to the strain. The elongation of the unit cell parallel to the cellulose chains was twice as high in juvenile wood as in mature wood. The (X-ray) Poisson ratio ν ca for crystalline cellulose in Norway spruce was calculated from the deformation of the unit cell. The average ν ca of earlywood was 0.28 ± 0.10 in juvenile wood and 0.38 ± 0.23 in mature wood. In latewood, the average ν ca was 0.48 ± 0.10 in juvenile wood and 0.82 ± 0.11 in mature wood. The average ν ca values were not directly correlated to the crystallite dimensions or to the mean MFA in juvenile and mature earlywood and latewood. The results show that the amorphous matrix has a definite effect on the deformation of cellulose crystallites.  相似文献   

9.
Japanese cedar (Cryptomeria japonica) preheated at 700°C was subsequently heated to 1800°C and characterized by electron microscopy, X-ray diffraction, and micro-Raman spectroscopy. The degree of disorder of carbon crystallites and the amount of amorphous phase decreased considerably with an increase in heat treatment temperature to 1400°C, while carbon crystallites clearly developed above this temperature, showing that the microstructure of carbonized wood undergoes drastic changes around 1400°C. Besides showing the bands for sp2-bonded carbon, the Raman spectra showed a shoulder near 1100 cm−1 assigned to sp3-bonded carbon. With an increase of heat treatment temperature, the peak position of the Raman sp3 band shifted to a lower frequency from 1190 to 1120 cm−1, which is due to the transformation of sp3-bonded carbon from an amorphous phase to a nanocrystalline phase. These data showed that the microstructure of carbonized wood from 700° to 1800°C consisted of the combination of sp2- and sp3-bonded carbon, which is probably due to the disordered microstructure of carbonized wood. It is suggested that the sp3-bonded carbon is transformed from an amorphous structure to a nanocrystalline structure with the growth of polyaromatic stacks at temperatures above 1400°C.  相似文献   

10.
Genetic parameters for various wood density traits were estimated in 29-year-old trees of 18 full-sib families of hybrid larch (Larix gmelinii var. japonica × Larix kaempferi) F1. Intra-ring density variation (IDV) was also evaluated using a model that expresses the pattern curve from earlywood to latewood as a power function. A high IDV indicates an abrupt change in wood density from earlywood to latewood. The ring width and wood density traits of individual rings were determined by X-ray densitometry. Overall wood density (RD) was shown to increase with increasing ring number, ranging from 0.42–0.59 g/cm3, whereas IDV of individual rings decreased gradually from pith outwards. Estimates of individual tree narrow-sense heritability of RD and IDV were 0.66 and 0.67, respectively. IDV showed negative genetic and phenotypic correlations with RD (r g = −0.99, r p = −0.72). The predicted genetic gains in latewood proportion and IDV were higher than that of RD. These results suggest that the intra-ring density variation is under moderate genetic control equivalent to wood density. The trend of increasing wood density from earlywood to latewood was associated with changes in both tracheid diameter and cell wall thickness.  相似文献   

11.
 Supercritical carbon dioxide (SC-CO2) was tested for its potential as a carrier solvent for preservative treatment of solid wood and wood-based composites. A preliminary trial showed that the treatability of solid wood varied with its original permeability and that the SC-CO2 treatment was not promising for refractory timber species such a Larix leptolepis Gordon. In contrast, 3-iodo-2-propynyl butylcarbamate (IPBC)/SC-CO2 treatment resulted in enhanced decay resistance without any detrimental physical or cosmetic damage in all structural-use wood-based composites tested: medium density fiberboard, hardwood plywood, softwood plywood, particleboard, and oriented strand board (OSB). Further trials under various treatment conditions [25°C/7.85 MPa (80 kgf/cm2), 35°C/7.85 MPa, 45°C/7.85 MPa, 35°C/11.77 MPa (120 kgf/cm2), and 45°C/11.77 MPa] indicated that although small changes in the weight and thickness of the treated materials were noted the strength properties were not adversely affected, except for a few cases of softwood plywood and oriented strand board. The results of this study clearly indicated that the treatment condition allowed SC-CO2 to transport IPBC into wood-based composites, and the optimum treatment condition seemed to vary with the type of wood-based composite. Received: October 24, 2001 / Accepted: February 15, 2002 Part of this work was presented at the 51st Annual Meeting of the Japan Wood Research Society, Tokyo, April 2001; and the 32nd Annual Meeting of the International Research Group on Wood Preservation, Nara, May 2001 Correspondence to:M. Muin  相似文献   

12.
This study evaluated the protection effectiveness of alcohol-borne reagents for the green color of ma bamboo (Dendrocalamus latiflorus Munro) and moso bamboo (Phyllostachys pubescens Mazel). The results show that the types and concentrations of alcohol-borne reagents, the kinds of solvent, and the conditions of treatment greatly affected the green color of these two bamboo species. Without alkali pretreatment, an excellent green color protection (a* = −14.5) was obtained when the ma bamboo culms were treated with 0.5% methanol-borne copper chloride (CuCl2) at 60°C for 30 min. Similar results were also obtained when ma bamboo culms were treated with 0.5% methanol-borne copper nitrate [Cu(NO3)2] at 60°C for 2 h (a* = −13.5). For moso bamboo, an attractive green color in the bamboo culms was achieved by treating the specimens with 1% methanol-borne copper acetate [Cu(CH3COO)2] at 60°C for 30 min. The a* value of treated specimens was −13.3. In addition, results demonstrated that ultrasonic treatment was more effective on green color protection than conventional water bath treatment. When moso bamboo was treated with 1% copper acetate at 60°C in an ultrasonic bath for only 15 min, a remarkable green color with an a* value of −13.6 was obtained on the bamboo epidermis.  相似文献   

13.
Eucalyptus camaldulensis × globulus and E. camaldulensis × grandis hybrids have been developed to combine the salt–waterlogging tolerance and high-quality wood fibre of their respective parents. The aim is to develop trees that will grow in relatively dry and/or saline environments and provide commercial wood products. Previous studies indicate that the hybrids exhibit faster growth than either of their pure species parents, and that there are significant differences in growth rates between them. We undertook a comparative study of the partitioning of above-ground biomass (AGB) to examine biomass and chloride (Cl) allocation of trees growing on two saline-irrigated sites in south-eastern Australia. Eucalyptus camaldulensis × globulus had a higher proportion of AGB in leaves (20–29% cf. 15–16%), and lower proportion in live branches (3–10% cf. 6–14%) than E. camaldulensis × grandis. The concentration of Cl was highest in the stembark (4.2–9.6 g kg−1) and lowest in the stemwood (0.6–2.0 g kg−1), suggesting that trees can export Cl through bark shedding. Total Cl content was strongly related to volume under bark (R2 = 0.99), and differences in partitioning of Cl into tree components differed between the hybrids in the same way as AGB. Preferential partitioning of Cl to live branches rather than foliage in E. camaldulensis × grandis suggests that this hybrid may be compartmentalising Cl to reduce the risk of Cl toxicity in the leaves.  相似文献   

14.
We characterized 14 anonymous nuclear loci from Pinus thunbergii Parl., an important pine species native to Japan. One hundred and twenty-six single nucleotide polymorphisms (SNPs) were identified from these loci, giving a frequency of 1 SNP per 51 bp. Nucleotide diversity (θ) ranged from 1.06 × 10-3 to 11.87 × 10-3, with an average of 4.99 × 10-3. Only one locus (mK45) deviated significantly from the Hardy-Weinberg equilibrium. Thirteen of 14 loci were applicable in other pine species. These loci will be useful for nucleotide variation studies and will provide material for SNP-based marker development in P. thunbergii and related species.  相似文献   

15.
TGA modeling of the thermal decomposition of CCA treated lumber waste   总被引：1，自引：0，他引：1  
 To guide the development of thermal decomposition methods for disposal of CCA treated wood, reactions during the thermal decomposition of CCA treated wood were modeled using thermogravimetric analysis (TGA), with special focus placed on arsenic volatilization. Simple inorganic compounds, such as As2O5, CuO, and Cr2O3, were used to model the thermal behavior of the inorganics in CCA treated wood. In air and nitrogen, arsenic (V) oxide began to volatilize at 600 °C during temperature ramps at 5 °C/min. During a 5 °C/min ramp in a hydrogen mix, arsenic (V) oxide began decomposition at 425 °C. Arsenic volatile loss from CCA treated wood can depend strongly on the gases produced by wood thermal decomposition. In the presence of As2O5, chromium (III) oxide and copper (II) oxide formed arsenates in air and nitrogen. Chromium arsenates began decomposition as low as 790 °C. This suggested that chromium arsenates in CCA treated wood formed during original preservative fixation may decompose as low as 790 °C. Copper arsenates were stable up to 900 °C in air, but showed only a limited range of stability in nitrogen. Depending on process conditions, the formation of copper arsenates may limit arsenic loss during thermal decomposition of CCA treated wood up to 900 °C. The thermal decomposition of inorganic oxides was influenced by interactions with wood and wood decomposition products. In a dry YP sawdust/As2O5 mix, arsenic (V) oxide volatilized at 370 °C during inert pyrolysis at 5 °C/min and at 320 °C during smoldering combustion at 5 °C/min. Thermal dwells of a dry YP/As2O5 mix showed no arsenic loss at 250 °C, but significant loss occurred during higher temperature dwells. During inert pyrolysis at 5 °C/min, the formation of complexes and hydrates were shown to prevent arsenic loss up to 400 °C. Received 14 July 1999  相似文献   

16.
This study examined the effect of alley cropping of Leucaena leucocephala and Faidherbia albida on wood biomass, maize grain yield and soil nitrogen status. The treatments were: trees planted alone at 1 × 5 m spacing; trees intercropped with maize and a sole maize crop. Mulch biomass averaged 6.18 and 0.97 t ha−1 for L. leucocephala and F. albida, respectively. Corresponding wood production was 1.71 and 1.11 t ha−1. Both total N and inorganic N (NO 3 − –N plus 4 + –N) were higher under F. albida and lowest under L. leucocephala. Similarly, foliar N concentration in maize was higher in plots intercropped with F. albida and least in L. leucocephala intercropping. Maize grain yield was little affected by the tree intercrop as competition for resources was reduced through periodic pruning and clean weeding. There was no gain in maize grain yield due to the presence of L. leucocephala and F. albida. These results suggest that alley cropping in Gario is justified for wood production but not for increasing maize grain yield. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

17.
Pathogenicity of 13 strains of entomopathogenic fungi belonging to genera Paecilomyces, Tolypocladium, Beauveria, Metarhizium, and Lecanicillium (=Verticillium) was evaluated on fourth instar larvae of Thaumetopoea pityocampa (Schiff.) (Lep.: Thaumatopoeidae). Larvae were treated individually by dipping into conidial suspension with the concentration of 1.0 × 105 conidia ml−1. All the tested isolates resulted in various levels of mortality (16–100%), and eleven of them were able to grow and sporulate on dead larvae. Mortality caused by three isolates of P. fumosoroseus, one isolate of Beauveria bassiana and one isolate of Metarhizium anisopliae were significantly higher than that of the other treatments. Three isolates of P. fumosoroseus, one isolate of P. farinosus, and one isolate of M. anisopliae showed mycelial growth and sporulation on significantly more cadavers compared to other treatments. Dose–mortality test was conducted with P. fumosoroseus (isolate no: 2679), which appeared to be the most promising isolate among the tested fungi, by spraying five concentrations of its conidia (1.0 × 106, 1.5 × 106, 7.5 × 106, 1.0 × 107 and 1.5 × 107 conidia ml−1). The estimation of the LC50 (95% confidence limits) was 3.4 × 106 (9.3 × 105 − 6.9 × 106) conidia ml−1. This study showed that P. fumosoroseus (isolate no: 2679) could be a good candidate as a microbial control agent against T. pityocampa in forest environment.  相似文献   

18.
Absorbing water from soil by roots in vascular plants is an important physiological function and plays an essential role on their water balance. The root hydraulic conductance (L P) determined by radical water transport inside the root is a major influence on the shoot water status, plant growth, and development. However, a few studies have focused on the effect of different substances on L P of roots, and the role of radical water transport was poorly understood. Based on the pressure-flux approach, this study used the roots of Fraxinus mandshurica seedlings with different treatments, i.e., distilled water, NH4NO3 solution, and HgCl2 to determine the effect of various substances on L P of roots. The objectives are: 1) to evaluate the difference in L P occurred between distilled water and NH4NO3 solution with various concentrations; and 2) to examine the changes of L P under distilled water and NH4NO3 solution with various concentrations after HgCl2 treatment. The results showed that L P of roots were 18.85×10−8 m/(s·MPa) in distilled water, 31.25–34.15×10−8 m/(s·MPa) in four NH4NO3 solutions (2, 4, 8 and 16 mmol/L), 14.69×10−8 m/(s·MPa) in distilled water after HgCl2-treated, and 9.63–13.57×10−8 m/(s·MPa) in four NH4NO3 solutions after HgCl2-treated, respectively. Aquaporins play an important role in regulating water uptake and transport in roots. NH4 + and NO3 − could stimulate activity of aquaporins, and L P of roots in NH4NO3 solution was distinctly 77% higher than in distilled water. Nevertheless, Hg2+ can inhibit activity of aquaporins, and and L P of roots decreased 22% in distilled water and 68% in NH4NO3 solution after treatment by HgCl2 respectively. These evidences suggested that both Hg2+-sensitive aquaporins and ion channels existing in the protoplasm and vacuole membranes could regulate root water uptake, transport, and integral plant water balance. __________ Translated from Acta Phytoecologica Sinica, 2005, 29(5): 706–712 [译自: 植物生态学报, 2005, 29(5): 706–712]  相似文献   

19.
欧阳华 《林业研究》1995,6(1):27-38
INTRODUCTIoNChangesinsoilNmineralizationratescouIdbeanearlywarningofsoilNavaila-bilityoreventualforestdeclinesinceNisoftenan.importantnutrientforgrowth(Keeneyl98O;Leaetal.l982;Vitouseketal-l982).Nitrogenmineralizationinvolvestwodistinctprocessesfammonification,inwhichNH:isformedfromorganiccom-pounds,andnitrification,theoxidationofNH:toNO3.ManystudiesofatmosphericdepositionimpactsonforestshavetargetedsoilNmineraIizationusingsimulatedaciddepositionundercontrolledlaboratoryconditions(T…  相似文献   

20.
Soil N transformations using the polyvinyl chloride (PVC) closed-top tube in situ incubation method were studied in Nanchang urban forests of the mid-subtropical region of China in different months of 2007. Four plots of 20 m × 20 m were established in four different plant communities that represented typical successional stages of forest development including shrubs, coniferous forest, mixed forest and broad- leaved forest. Average concentrations of soil NH 4 + -N from January to December were not different among the four plant communities. The concentrations of soil NO 3 - -N and mineral N, and the annual rates of ammonification, nitrification and net N-mineralization under the early successional shrub community and coniferous forest were generally lower than that of the late successional mixed and broad-leaved forests (p<0.05). Similar differences among the plant communities were also shown in the relative nitrification index (NH 4 + -N/NO 3 - -N) and relative nitrification intensity (nitrification rate/net N-mineralization rate). The annual net N-mineralization rate was increased from younger to older plant communities, from 15.1 and 41.4 kg·ha -1 ·a -1 under the shrubs and coniferous forest communities to 98.0 and 112.9 kg·ha -1 ·a -1 under the mixed and broad-leaved forests, respectively. Moreover, the high annual nitrification rates (50-70 kg·ha -1 ·a -1 ) and its end product, NO 3 - -N (2.4-3.8 mg·kg -1 ), under older plant communities could increase the potential risk of N loss. Additionally, the temporal patterns of the different soil N variables mentioned above varied with different plant community due to the combined affects of natural biological processes associated withforest maturation and urbanization. Our results indicated that urban for- ests are moving towards a state of "N saturation" (extremely nitrification rate and NO 3 - -N content) as they mature.  相似文献   

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