Variation analysis and fine family selection on half-sib progenies from clonal seed orchard of Pinus massoniana

Variation of traits that include height, diameter at breast height (DBH), stem volume, crown width, straightness, wood basic density, tracheid length and width of open-pollinated progenies from clonal seed orchard of Pinus massoniana was analyzed. Differences in traits such as growth, tree form and wood quality among families was significant, which indicated that the improvement potential was notable. Heritability of height and wood basic density reached 0.691 and 0.640, respectively. According to a correlation analysis between traits, stem straightness could be improved indirectly when growth traits are improved; growth traits were significantly correlated with wood basic density; and wood basic density was not significantly correlated with length and width of the tracheid. Under the selection ratio of 10%, genetic gains were 19.74% and 19.32% respectively, and selected families from the progeny test stands at the age of five years and eight years were the same. Genetic correlation of height, DBH and stem volume was also significant at the level of 0.01. These show that selection of the short rotation of P. massoniana for pulp and paper use would be efficient for five-year-old trees. According to the comparison of the heritability of all the traits and taking into account the result of canonical correlation analysis, height could be considered as the most important index for selection. Given wood quality of all the families, and flowering and fruit settings of the clones in a seed orchard, twelve fine families were selected at 10% selection ratio of height growth and stem volume. Translated from Scientia Silvae Sinicae, 2005, 41(6): 43–49 [译自: 林业科学]     

Key roles of leaves, stockplant age, and auxin concentration in vegetative propagation of two African mahoganies: Khaya anthotheca Welw. and Khaya ivorensis A. Chev

Leaf area, IBA concentration and age of stockplants were all found to be important factors for successful rooting for vegetative propagation using single-node cuttings of the two main African mahogany species: Khaya anthotheca and K. ivorensis. Cuttings with leaf area of 30–50 cm² had the best rooting percentage and cuttings with about 30 cm² had the most number of roots per cutting in K. anthotheca. Khaya ivorensis, cuttings with 10–30 cm² leaf area had the highest rooting percentage. Cuttings collected from 1-year-old stockplants recorded the highest rooting percentage and largest number of roots per cutting. Cuttings from 3-year-old stockplant of the same seeds sources had the lowest rooting suggesting aging negatively impacted rooting ability. The effect of auxin concentration, on rootability was examined with cuttings of K. anthotheca. An IBA concentration of 0.8% was the best exogenous auxin concentration for percentage rooting, number of roots per cutting and the length of the longest root per cutting.     

Density structure and growth dynamics of a Larix principis-rupprechtii stand for water conservation in the Wutai Mountain Region of Shanxi Province, North China

To discover the site adaptability and density suitability of Larix principis-rupprechtii as a water conservation forest in Wutai Mountain, Shanxi Province, the growth process and diameter distribution characteristics of 10-year-old artificial L. principis-rupprechtii forests with density structures of 2600 trees/hm² and 3500 trees/hm² were studied using trunk analysis of a sample tree. The results showed that: 1) The tree height increment of the two kinds of forests were the same, and it was almost not affected by density. However, the growth process of the diameter and timber volume showed a great distinction. The growth status and density structure of the low density forest were superior to the high density forest. 2) The skewness (S _k) of diameter distribution had great distinction. The S _k (0.01) of the low density forest approached a normal distribution, which showed that the density structure was reasonable, while the S _k (0.45) of the high density forest was partial to a normal distribution, which showed that the density structure was on the high side. The kurtosis (K) of the two forests (one was −0.64, the other was −0.74) had little distinction and the density factor had limited function to forest polarization. 3) The increment of diameter at breast height, timber volume and trunk stock of the low density forest increased yearly without the effect of density. However, the increment of high density forests had declined from the sixth year, which was restricted by high density. 4) The reasonable density of the 10-year-old L. principis-rupprechtii artificial forest was about 2600 trees/hm², which is also the reasonable planting density if the utilization of double cutting is not considered. __________ Translated from Science of Soil and Water Conservation, 2007, 5(1): 1–6 [译自: 中国水土保持科学]     

Carbon storage of artificial forests in rehabilitated lands in the upper reaches of the Yellow River

We studied 10-to 27-year-old artificial forests on rehabilitated lands in the upper reaches of the Yellow River with the objective of comparing the carbon densities of various artificial and natural forests. Under artificial plantations, the vegetation layer (including roots) had a mean carbon density of 111.3 t/hm², the litter layer a density of 5.1 t/hm², and the soil layer a density of 64.9 t/hm². These values accounted for 28.6%, 13.8%, and 61.0% of their respective counterparts in the natural secondary forests under the same site conditions in the region. The ratios of carbon density among vegetation, litter, and soil pools were 39.6:1.8:58.6 for artificial forests and 57.4:2.7:39.9 for natural forests. The carbon densities of the vegetation and litter layers increased exponentially with forest age. The total carbon density ratios were also increasing gradually. Although the mean total carbon density of the artificial forests in the rehabilitated lands was 281.2 t/hm² in the experimental area, it accounted for only 41.5% of the carbon density of the natural secondary forests (677.4 t/hm²). The annual increase in total carbon density of artificial forests was as high as 15.2 t/hm², which was 11.7% more than that of natural forests and 6.8 times higher than that (1.95 t/hm) of artificial forests in the entire country as measured during 1994–1998. This indicates that growth and carbon storage capacity of artificial forests in the rehabilitated lands were higher than those of forests on the barren hills and the secondary forests. We concluded that the conversion project from croplands to forests and grasslands based on scientific principles is very important in the formation of carbon sinks for reducing greenhouse effects. __________ Translated from Journal of Beijing Forestry University, 2005, 27(6): 1–8 [译自: 北京林业大学学报, 2005, 27(6): 1–8]     

Windthrow after Shelterwood cutting in Picea abies Peatland forests

The aim of the study was to address the question of whether shelterwood cutting should be discouraged as a forest regeneration method in Norway spruce (Picea abies (L.) Karst.) forests on highly productive peatlands due to a higher risk of windthrow in such forests. The total extent of windthrow was observed during six years after shelterwood cutting in nine spruce forests on fertile peatlands in north, central and south Sweden. Shelterwoods at densities of 140 and 200 stems ha^‐1 were studied. At the end of the six year study period, 43% of all trees in the sparser shelterwoods and 38% of the trees in the denser shelterwoods had blown down. With respect to results from recent studies of the development of naturally regenerated and planted seedlings under the shelter trees, the extent of windthrow was regarded acceptable. Analysis of wind data from national weather stations close to the experiments showed that the acceptable extent of windthrow could not be explained by low frequencies of high winds during the shelterwood period. On the contrary, according to the wind observations made at the weather stations selected in central and south Sweden, the annual number of days with high winds (>21 ms^‐1) during the six years after the shelter‐wood cutting was larger than the average high wind frequency for the last 40 years. Observations of maximum wind speeds show that the mean annual gale force during the shelterwood period was higher than the long term average. Thus, the results from this study do not justify avoidance of shelterwood cutting in spruce peatland forests because of the risk of windthrow. Each of the shelterwoods in the experiment was located close to a large clearcut, and the shelterwood cuttings were carried out as heavy thinnings. For further reduction of windthrow, denser shelterwoods and no clearcutting in adjacent stands are suggested when using shelterwood systems in practical forestry.     

Lignin characterization of triploid clones of Populus tomentosa Carr.

In order to understand the structural characteristics of lignin in triploid clones of Populus tomentosa and its changes in the processes of pulping and bleaching, milled wood lignin (MWL), lignin carbohydrate complex (LCC) and the residual lignin from kraft pulp (KP) and sulfite pulp (SP) were isolated and analyzed by Fourier transform infrared (FTIR) spectrum and ¹³C nuclear magnetic resonance (NMR). The most diagnostic peaks were assigned and the differences were discussed. The spectral patterns reveal that triploid P. tomentosa shows the specific features of hardwood from temperate areas, but in the spectrum of FTIR, the strength ratio of A 1270 cm⁻¹ to A1226 cm⁻¹ is 0.88, higher than the average of hardwood from temperate areas, which will make the lignin delignification more difficult during pulping and bleaching. The LCC from triploid P. tomentosa is mainly composed of xyloglucan and glucuronic acid, and other glucides have much lower ratio. In LCC FTIR, there are three peaks at 1 427, 1 329 and 1 046 cm⁻¹, indicating that both semi-cellulose and cellulose could exist in LCC, and that there might be relationships between cellulose and lignin. Compared with the residual lignin from KP and SP, the condensed structure in KP is more than that in SP.     

立地类型对长白山天然白桦林生态系统碳储量的影响

利用相对生长方程与碳/氮分析法,对比分析长白山天然白桦林在7个立地类型(阳坡上、中、下部与阴坡上、中、下部及谷地)上的生态系统碳储量(植被与土壤)、净初级生产力与年净固碳量,揭示立地类型对温带白桦林生态系统碳库与固碳能力的影响规律。结果表明:①长白山天然白桦林植被碳储量(45.61 87.22 t·hm^-2)呈阴坡上、中部与谷地>阳坡上、中部与阴坡下部>阳坡下部变化趋势,且高立地型显著高于低立地型50.8% 91.2%(P<0.05),中立地型高于低立地型20.4% 44.4%(P>0.05);②土壤碳储量(66.71 158.51 t·hm^-2)呈阳坡上部、阴坡中部与谷地>阳坡中、下部与阴坡下部>阴坡上部变化趋势,且高立地型显著高于低立地型99.3% 137.6%(P<0.05),中立地型高于低立地型40.7% 67.0%(P>0.05);③生态系统碳储量(139.44 231.12 t·hm^-2),呈阴坡中部与谷地>阳坡上部与阴坡下部>阳坡中、下部与阴坡上部变化趋势,且高立地型显著高于低立地型35.6% 65.7%(P<0.05),中立地型高于低立地型5.8% 34.7%(P>0.05);④植被净初级生产力(4.92 11.25 t·hm^-2·a^-1)和年净固碳量(2.32 5.32 t·hm^-2·a^-1)均呈阴坡上、中部>阳坡上、下部与阴坡下部及谷地>阳坡中部变化趋势,且高立地型显著高于中、低立地型42.5% 128.7%和45.2% 129.3%(P<0.05),中立地型高于低立地型10.6% 56.3%和14.2% 53.4%,但仅阴坡下部提高显著。因此,长白山白桦林生态系统碳库与固碳能力均受到立地类型的强烈影响,故对其碳汇功能评价应考虑其立地分异规律性。     

Propagation techniques on root turion sprout browse ofPopulus davidiana Dode

The root segments selected from dominant trees ofPopulus davidiana Dode were taken as reproductive material and were buried in different depths to carry out the reproduction of root turion sprout. The affecting factors of gemination rate, survival rate, and height growth for cutting wood of root sprout were comparatively analyzed. The results showed that the best suitable substrate for burying root is pearlite, with a germination rate of 15.16%. 3–4-cm root segments has the highest rate of germination (12.4%). The mixture of sand and soil (2∶1) is the best cutting substrate, with a survival rate of 81.3%, while as to height growth of cutting wood, the mixture of turfy and soil (1∶1) is the best. The cutting woods selected from different positions of stem show difference in height growth. The cutting wood from top stem is higher obviously than those from middle or low stem. Biography: XING Ya-juan (1969-), female, assistant researcher in Forest Research Institute of Heilongjiang Province, Harbin 150040, P. R. China. Responsible editor: Song Funan     

近自然森林经营在德国的应用成效分析

[目的]分析德国推行近自然森林经营20年来的经营效果,总结德国推行近自然森林经营的经验。[方法]在明晰近自然森林经营原则的基础上,基于两期(间隔期10年)资源清查数据对比,对德国大面积推行近自然森林经营20年的经营效果进行分析。[结果]两期资源清查数据表明,德国采用近自然经营20年后,针叶林如挪威云杉和欧洲赤松的面积显著减少,阔叶林和针阔混交林面积持续增加;阔叶树种蓄积平均增长量约为15 m~3·hm~(-2),针叶树种蓄积平均增长4 m~3·hm~(-2),挪威云杉是唯一蓄积下降的树种,下降了5 m~3·hm~(-2);近自然度等级变化表明,人工林面积在减少,而近自然森林的面积在增加,甚至符合原始林等级的森林面积也在增加。[结论]实现近自然森林经营的目标是一个长期的过程,联邦政府促进和保护森林的政策以及林场主所采用的先进的森林经营技术也是德国森林每公顷蓄积达到336 m~3的重要原因;在近自然森林经营的原则下,德国森林中针阔混交林比例显著增加;将近自然程度不高的人工林经营转化为近自然的森林生态系统是德国森林经营所面临的主要问题。     

Carbon sink in Phoebe bournei artificial forest ecosystem

Biomass, carbon content, carbon storage and spatial distribution in the 32-year-old Phoebe bournei artificial forest were measured. The mean biomass of the forest stand was 174.33 t/hm², among which the arbor layer was 166.73 t/hm², which accounted for 95.6%. Carbon contents of stems, barks, branches, leaves, root, shrub layer, herb layer, lichen layer and litter layer were 0.5769 g C/g, 0.4654 g C/g, 0.5232 g C/g, 0.4958 g C/g, 0.4931 g C/g, 0.4989 g C/g, 0.4733 g C/g, 0.4143 g C/g, 0.3882 g C/g, respectively. The mean carbon content of soil was 0.0139 g C/g, which reduced gradually along with soil depth. Total carbon storage of the P. bournei stand ecosystem was 227.59 t/hm², among which the arbor layer accounted for 40.13% (91.33 t/hm²), the shrub layer accounted for 0.17% (0.38 t/hm²), the herb layer accounted for 0.76% (1.71 t/hm²), the lichen layer accounted for 0.28% (0.63 t/hm²), and the litter layer accounted for 0.29% (0.66 t/hm²). Carbon content (0–80 cm) of the forest soil was 58.40% (132.88 t/hm²). Spatial distribution ranking of carbon storage was: soil layer (0–80 cm) > arbor layer > herb layer > litter layer > lichen layer > shrub layer. Net production of the forest stand was 8.5706 t/(hm²·a), in which the arbor layer was 6.6691 t/(hm²·a), and it accounted for 77.82%. Net annual carbon sequestration of the P. bournei stand was 4.2536 t/(hm²·a), and the arbor layer was 3.5736 t/(hm²·a), which accounted for 84.01%. __________ Translated from Scientia Silvae Sinicae, 2008, 44(3): 34–39 [译自: 林业科学]     

Mating patterns in an indoor miniature <Emphasis Type="Italic">Cryptomeria japonica</Emphasis> seed orchard as revealed by microsatellite markers

To evaluate the practical application of an indoor seed orchard, we compared the seed production, final germination rates and mating patterns of potted Cryptomeria japonica D. Don clones in two miniature seed orchards: one in a glasshouse and the other outdoors. There was no statistically significant difference in total seed production between the orchards (P = 0.275, ANOVA). However, the final germination rate of seeds produced in the indoor orchard was significantly lower than that of seeds produced in the outdoor orchard (P < 0.01, Wilcoxon test). The average self-fertilization rate was higher in the indoor orchard (27.2%) than in the outdoor orchard (5.6%), and this parameter was strongly associated with the reduced final germination rates of the seeds harvested in the glasshouse. Pollen contamination was considerably lower in the indoor seed orchard (48.9% in the outdoor seed orchard and 4.4% in the indoor seed orchard). χ² tests indicated that the paternal contributions of each constituent clone differed significantly in both orchards (P < 0.001 in both cases). The strong variations in paternal contributions among indoor orchard clones was significantly correlated with their respective pollen production capacities (Spearman ρ = 0.693, P < 0.001). To reduce the high self-fertilization rates, we recommend the use of orchard clones with similar pollen production capacity in indoor seed orchards.     

Biocycle of nitrogen in a Cyclobalanopsis glauca-dominated evergreen broad-leaved forest in East China

The nitrogen (N) cycling was elucidated in a 40-year-old subtropical evergreen broad-leaved forest dominated by Cyclobalanopsis glauca growing on red soil in Zhejiang Province, East China. The concentrations of N in the representative species ranged from 0.49% to 1.64%, the order of which in various layers was liana and herb layers > understory layer > tree and subtree layers; in various organs was leaf > branch > root > trunk; and aboveground parts > underground parts. The sequence of the concentrations of N in C. glauca was understory > tree > subtree layer; young and high-growing > old organs; reproductive > vegetative organs. Seasonal dynamics of the concentrations of N in C. glauca in the tree and subtree layers was comparatively stable. It was lower in autumn (October) in root, branch, and leaf in the tree layer, and low in January in the understory. There was no evident change in regularity of the concentrations of N in varying diameter classes. The concentrations of N in the litterfall, precipitation, throughfall, litter layer, and soil were 0.74%–2.30%, 0.000,038%, 0.000,09%, 1.94%, and 0.59%, respectively. The standing crop of N in the plant community was 1,025.28 kg/hm², accumulation in the litter layer was 224.88 kg/hm², and reserve in the soil was 55,151 kg/hm². Annual retention of N was 119.47 kg/hm², return was about 84.13 kg/hm², among which litterfall was 78.49 kg/hm² and throughfall, 5.64 kg/hm². Annual absorption of N was 203.60 kg/hm². Annual input of N through incident precipitation was 4.88 kg/hm². Compared with other forest types, cycling rate of N in the community was lower than in deciduous broad-leaved forests, rain forests, and mangroves, and was moderate in evergreen broad-leaved forests. N use efficiency of this forest was moderate among the forest types cited. According to the characteristics of the biocycle of phosphorous, it was concluded that N availability in the soil of this forest was not lower, and phosphorous not N was the limiting factor in the growth of plants in this community. __________ Translated from Acta Ecologica Sinica, 2005, 25(4): 740–748 [译自: 生态学报, 2005, 25(4): 740–748]     

Diversity and spatio-temporal dynamics of dead wood in a temperate near-natural beech forest (<Emphasis Type="Italic">Fagus sylvatica</Emphasis>)

The diversity, spatial patterns and temporal dynamics of dead wood were examined within the near-natural beech forests (Fagus sylvatica) of Serrahn (North-eastern Germany). Data were collected in an 8 ha sample plot and in two permanent plots (0.36 and 0.25 ha) that had been established at the end of the 1960s. The mean volume of dead wood was 94 m³ ha⁻¹, amounting to 14% of the total volume of all trees. The dead wood displayed a large variation in dead wood type, tree size and decay class. Standing dead wood accounted for about one-third of the total dead wood volume. The densities of standing dead trees were about 10% of the densities of the living trees over a wide range of diameters. The overall spatial distribution of dead trees exhibited a random pattern. Among the different dead wood types, standing entire dead trees and uprooted trees deviated from this pattern by displaying a significantly aggregated pattern. In the permanent plots a high mortality of overstorey trees was observed (1.3% year⁻¹) and the average amount of dead wood increased greatly from 2.9 to 111.6 m³ ha⁻¹ over the 35-year observation period. The near-natural beech forests of Serrahn have experienced a long period of low human interference. Nevertheless, our results suggest that the structure and dynamics of dead wood are strongly affected by the last major disturbance events that took place at the end of the Middle Ages. Information about the forest history is therefore a basic requirement when interpreting the results obtained in near-natural forests.     

Effects of forest canopy gap on biomass of Abies faxoniana seedlings and its allocation in subalpine coniferous forests of western Sichuan

Using a strip transect sampling method, the density, height (≤ 100 cm), basal diameter and components of biomass of Abies faxoniana seedlings, living in a forest gap (FG) and under the forest canopy (FC) of subalpine natural coniferous forests in western Sichuan, were investigated and the relationships among different components of biomass analyzed. The results indicated that the density and average height (H) of A. faxoniana seedlings were significantly different in the FG and under the FC, with the values being 12903 and 2017 per hm², and 26.6 and 24.3 cm. No significant differences were found in the average basal diameter (D) and biomass. The biomass allocation in seedling components was significantly affected by forest gap. In the FG, the biomass ratio of branch to stem reached a maximum of 1.54 at age 12 and then declined and fluctuated around 0.69. Under the FC, the biomass ratio of branch to stem increased with seedling growth and exceeded 1.0 at about age 15. The total biomass and the biomass of leaves, stems, shoots and roots grown in the FG and under the FC were significantly correlated with D ² H. There were significant and positive correlations among the biomass of different components. __________ Translated from Chinese Journal of Applied Ecology, 2007, 18(4): 721–727 [译自: 应用生态学报]     

Vegetative propagation of two endemic species of <Emphasis Type="Italic">Cloezia</Emphasis> Brongn. &; Gris for conservation and mining revegetation activities in New Caledonia

A study to determine the best vegetative propagation protocol was carried out for two species of the endemic genus Cloezia for conservation and mining revegetation activities in New Caledonia. Effects of clonal capacities and auxin treatments on rooting of C. buxifolia and C. aquarum semi-hardwood cuttings taken from wild populations were evaluated in four experiments. Different phenotypes varied in their capacity to root (from 0 to more than 80%) and this underlines the importance of collecting cuttings from different plants when revegetation programs are based on vegetative propagation. The experiments evaluated the effectiveness of IBA at 5, 10 and 20 g kg⁻¹, IAA at 5 and 10 g kg⁻¹ and NAA at 1 and 2 g kg⁻¹ treatments to enhance rooting of C. buxifolia tip cuttings and C. aquarum tip and stem cuttings compared to control cuttings with no applied auxin. With the exception of IAA, auxin treatments enhanced the percentage of cuttings with roots and significantly improved the number of roots per cutting and root length. In this study, the best treatment is 10 g kg⁻¹ IBA for C. buxifolia. For C. aquarum, 20 g kg⁻¹ IBA significantly enhances quantitatively and qualitatively rooting of both tip and stem cuttings.

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Résumé  Cette étude porte sur la définition d’un protocole de multiplication végétative optimale de deux espèces du genre endémique Cloezia dans un but de conservation et de revégétalisation en Nouvelle-Calédonie. Quatre essais visent à déterminer les potentialités clonales de différents individus et l’effet de divers traitements hormonaux sur l’enracinement de boutures de C. buxifolia et C. aquarum. L’enracinement des boutures dépend du pied-mère sur lesquelles elles sont récoltées et peut varier de 0 à plus de 80%, ce qui indique l’intérêt de la méthode d’échantillonnage lors de la collecte des boutures. L’effet de traitements hormonaux à base d’AIB, AIA et ANA à différentes concentrations, respectivement de 5, 10 et 20 g kg⁻¹, 5 et 10 g kg⁻¹ et 1 et 2 g kg⁻¹ est également étudié sur des boutures de tête de C. buxifolia et des boutures de tête et de tige de C. aquarum. Ces traitements améliorent le pourcentage d’enracinement et augmentent significativement le nombre de racines produites et la longueur des racines des boutures de Cloezia, à l’exception des traitements à base d’AIA. Dans cette étude, le meilleur traitement est 10 g kg⁻¹ d’AIB pour C. buxifolia et 20 g kg⁻¹ d’AIB pour C. aquarum.

     

Aboveground biomass of three conifers in the Qianyanzhou plantation, Jiangxi Province, China

Regressive models of the aboveground biomass for three conifers in subtropical China—slash pine (Pinus elliottii), Masson pine (P. massoniana) and Chinese fir (Cunninghamia lanceolata)—were established. Regression analysis of leaf biomass and total biomass of each branch against branch diameter (d), branch length (L), d ³ and d ² L was conducted with functions of linear, power and exponent. A power law equation with a single parameter (d) was proved to be better than the rest for Masson pine and Chinese fir, and a linear equation with parameter (d ³) is better for slash pine. The canopy biomass was derived by adopting the regression equations to all branches of each individual tree. These kinds of equations were also used to fit the relationship between total tree biomass, branch biomass, foliage biomass and tree diameter at breast height (D), tree height (H), D ³ and D ² H, respectively. D ² H was found to be the best parameter for estimating total biomass. However, for foliage biomass and branch biomass, both parameters and equation forms showed some differences among species. Correlations were highly significant (P<0.001) for foliage biomass, branch biomass and total biomass, among which the equation of the total biomass was the highest. With these equations, the aboveground biomass of Masson pine forest, slash pine forest and Chinese fir forest were estimated, in addition to the allocation of aboveground biomass. The above-ground biomass of Masson pine forest, slash pine forest and Chinese fir forest was 83.6, 72.1 and 59 t/hm² respectively, and the stem biomass was more than the foliage biomass and the branch biomass. The underground biomass of these three forests which estimated with others’ research were 10.44, 9.42 and 11.48 t/hm², and the amount of carbon-fixed were 47.94, 45.14 and 37.52 t/hm², respectively. __________ Translated from Chinese Journal of Applied Ecology, 2006, 17(8): 1382–1388 [译自: 应用生态学报]     

30个桉树无性系人工林碳储量分析

通过对国营雷州林业局30个5年生桉树无性系人工林的调查、试验,旨在阐明不同桉树无性系人工林碳储量的变化规律及营建桉树碳汇林的合理措施.结果表明:30个桉树无性系人工林生态系统平均碳储量为148.743 t·hm-2,高于之前学者研究的桉树人工林碳储量,其中,乔木层和土壤层分别占34.39％、61.88％;乔木层平均碳储量达51.948 t·hm-2,不同无性系间差异极显著(p＜0.01),其中,23(101-1)、25(179-1)、4(BU1)、26(184-1)号无性系表现最优;土壤层的平均碳储量为92.033 t·hm-2,不同无性系土壤层碳储量差异不明显;灌木层、草本层、凋落物层碳储量分别是2.430、0.731、1.592 t·hm-2,占比例较小.营建桉树碳汇林关键在于无性系的正确选择.     

Effects of Different Management Regimes for Cutover Areas on Soil Carbon Storage in Chinese Fir Plantations

Based on data collected (through local observations) for several consecutive years, comparative analyses of Chinese fir plantations in Huitong, Hunan, were made. Results show that, before harvesting, carbon storage in forest soils in these 22-year-old plantations (0–60 cm) amounted to 160.38 t/hm²; 1 year after a 100% clear-cutting, loss of carbon storage in the soil (0–60 cm) of cutover areas was 35.00%; 2 years later, the rate was 44.65%; and, after 3 years, the rate was 43.93% compared with a control area of a standing forest. Three years after 50% thinning and 100% clear-cutting, the loss of carbon storage in the soil (0–60 cm) of cutover areas was 16.14 and 45.15%, respectively. There existed an evident difference in carbon storage in the soil (0–60 cm) of cutover areas in four kinds of management regimes, which followed the order: closed Chinese fir forests (108.20 t/hm²) > fallow lands after farming (92.68 t/hm²) > commercial forests (85.80 t/hm²) > naturally regenerated forestlands after harvesting. Carbon storage in unburnt soil (0–45 cm) reached 73.36 t/hm², which was 15.20 t/hm² higher than that in the soil of burnt areas. A total of 20.7% of carbon storage in the soil (0–45 cm) of burnt areas was lost 40 days after burning. Carbon storage in surface soil (0–15 cm) was higher than in the lower soil layer, which amounted to 30.04% (0–60 cm) and 53.52% (0–30 cm) of total carbon storage in the soil. Translated from the Journal of Central South Forestry University, 2004, 24(1) (in Chinese)     

Parameters affecting shoot production and rooting of cuttings from lodgepole pine hedges

By propagating lodgepole pine (Pinus contorta) cuttings in vivo, we obtained after 7 growing cycles (ca 3.5 years) in a greenhouse, sufficient number of cuttings from most families to establish clonal progeny tests. Twenty-one full-sib families with approximately 20 clones per family were studied for five years. Years when cuttings were set, families within latitude and clones within families differed significantly in rooting percentages, with the variance components 4.2%, 8.2% and 9.5%, respectively. One way to get a frequent and uniform rooting is to take cuttings from non-leading shoots since they have higher rooting percentage than leading shoots. Neither total length of the cuttings nor length of the primary needles were significantly correlated to rooting percentage. With appropriate management of the ortets and the cuttings during rooting, most clones could be included in a cutting propagation program.     

Function and value of water conservation in different age classes of Acacia mangium plantations

For this paper, we studied the water-holding capacity of canopy, vegetation layer under canopy and litter layer, the water-holding capacity and permeability of soil as well as their changes with growth of stands in Acacia mangium plantations of three different age classes (four-, seven-and 11-year-old). Results show that total water-holding above ground in the order of 11-year stand age (52.86 t/hm²)>seven-year stand age (41.90 t/hm²)>seven-year stand age (25.78 t/hm²), the increment tendency increased with stand age. Similar sequence also obtained on the water-holding capacity and permeation capacity of soil (0–40 cm). The total water-storage capacity both above ground and soil in four-year-old, seven-year-old and 11-year-old of A. mangium plantations were 2,023.0, 2,158.4 and 2,260.4 t/hm², respectively, and the all value of water conservation were 1,372.70, 1,474.42 and 1,549.91 yuan (RMB)/hm², respectively. Therefore, A. mangium plantation had a good ability to modify soil structure and good water conservation function. __________ Translated from Journal of Soil and Water Conservation, 2006, 20(5): 5–8, 27 [译自: 水土保持学报]