Provenance and family variation in growth performance of Eucalyptus tereticornis (Sm.) in a provenance cum progeny trial in Midnapore, India

Eucalyptus tereticornis Sm. is an important species for agroforestry and commercial plantations in India. Results of a combined provenance–progeny trial of E. tereticornis laid out in 2002 at Midnapore (West Bengal) located in eastern tropical region of India are reported and discussed. Twelve provenances representing 70 families from Australia and Papua New Guinea were evaluated up to the age of 3 years. As a local seed source open-pollinated seed collected from a land race, i.e., Mysore gum (commonly known as Eucalyptus hybrid) was used to serve as check material (control). Significant variation in plant height, clean stem height, girth at breast height (GBH) and field survival was observed due to provenances, as well as families within provenances. This offers an ample scope to a breeder for increasing the growth and productivity in E. tereticornis through selection of provenances and families having potential for higher productivity. Heritability (narrow sense) values were appreciable for growth traits. Within provenance individual tree heritability estimates for height, clean stem length, GBH and number of branches at age 3 years were 0.318, 0.215, 0.269 and 0.231, respectively (assuming a coefficient of relationship of 0.4 for open-pollinated families of E. tereticornis). Provenance of Walsh River, Queensland Australia performed best for plant height, clean stem height, GBH, number of branches and field survival. Apart from this, the provenance from Oro bay to Emo, Papua New Guinea and Burdekin river, Queensland also showed good performance. Provenance from Yurammie, SF from New South Wales performed poorest for growth and survival. Correlations on growth traits were high and statistically significant, indicating that substantial gains could be achieved through indirect selection for one trait based on the direct selection for another. Age–age genetic correlations between age 1 and 3 years for the growth traits were highly significant and positive. Geographic clinal variation pattern was observed as latitude was negatively correlated with height and GBH (P < 0.05); longitude with number of branches (negative, P < 0.05). Fair differences were observed between phenotypic and genotypic coefficient of variability.     

Genetic and site effects on stem breakage in Pinus tecunumanii

Fifteen provenance/progeny tests of Pinus tecunumanii (Schw.) Eguiluz et Perry were assessed for upper-crown stem breakage at 5 to 8 years of age in Brazil, Colombia and South Africa. Five year results indicated that the mean percent stem breakage was moderate in Colombia (14% to 21%), low in South Africa (2% to 6%) and very low in Brazil (<1%). In the Colombian tests, trees from provenances of Mexican origin were more susceptible to wind damage than those from Central America, 20% versus 14%. Provenance order of percent stem breakage at 5 years of age in Colombia was Montebello (27%), La Soledad (25%), San Jose (20%), Chempil (20%), Jitotol (18%), Las Piedrecitas (18%), Celaque (17%), Km 47 (16%), San Vicente (13%), San Jeronimo (13%), San Lorenzo (12%) and Las Trancas (7%). Two half-sib progeny tests assessed at 8 years of age in Colombia with trees from the Mountain Pine Ridge source of P. tecunumanii exhibited 13% stem breakage. Family variation in stem breakage ranged from 0 to 44% in Colombia and 0 to 33% in South Africa at 5 years of age and were highly significant. The Spearman rank correlations in stem breakage of 36 half-sib families common to tests in Colombia and South Africa were r=0.13 and not significant. Family heritabilities for stem breakage at 5 and 8 years of age ranged from 0.17 to 0.63. Results indicate that stem breakage was more common on trees with branches of large diameter and was not strongly related to growth rate.     

思茅松自由授粉家系遗传参数与早期选择分析

[目的]通过对思茅松自由授粉子代测试林的生长与形质性状遗传参数的估计,进行优良家系选择,为建立思茅松高世代种子园及培育优良无性系苗木提供种质资源。[方法]采用随机区组试验设计,在214个思茅松自由授粉家系子代测试林中选择胸径、地径、树高、枝下高、冠幅、通直度、树干圆满度、树冠圆满度、材积及地上生物量等生长与形质性状,利用线性混合模型进行遗传参数的估计,进行优良家系筛选。[结果]思茅松自由授粉子代测试林生长与形质性状的遗传参数在家系间差异极显著。各性状的家系遗传力较高,其中,地径的家系遗传力最大(1.105)。材积的预期遗传增益高于地上生物量,利用家系/家系内选择方法进行优良家系的筛选,材积的预期遗传增益为60.75%,入选家系为60个;地上生物量的预期遗传增益为44.22%,入选家系为66个。轮盘数、通直度和树干圆满度对材积和地上生物量都有显著影响。[结论]在早期选择中,形质性状的遗传变异对思茅松自由授粉优良家系的选择有重要参考作用,4年生思茅松自由授粉家系子代测试林中各性状存在着丰富的遗传变异,在早期选择中可以筛选出适合不同培育目标的优良家系,最大限度挖掘其遗传潜力。     

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]     

Conservation and use of the Pinus chiapensis genetic resource in Colombia

The species Pinus chiapensis is under severe pressure from forest conversion to agriculture and fuelwood cutting. These trends are certain to continue and methods for conservation and wise use of the genetic resource must be implemented soon in Mexico and Guatemala as well as in those countries where the species can be grown on a commercial basis. A total of 101 open-pollinated families from nine provenances of Pinus chiapensis have been established in trials and gene conservation banks by Smurfit Carton de Colombia since 1981. The best provenances for growth rate have been Cotzal, La Trinidad and Pohlo. A tree improvement program with grafted seed orchards is underway.     

柏类引种试验研究

对柏类４个树种墨西哥柏,绿干柏,垂柏,巨柏共１２个种源的引种表明,不同树种和种源树高,胸径增最大年份分别出现在造林后第４年和第５年;造林后１０ａ,lay status     

Cloning of erect,thornless, non-browsed nitrogen fixing trees of Haiti's principal fuelwood species (Prosopis juliflora)

A progeny trial in Haiti compared 70 open-pollinated families ofProsopis representing seed sources from Haiti, Peru, Chile, Argentina and southwestern US. At the end of 4 years growth, the tallest 6 families were of Peruvian origin. Some of these Peruvian trees (probablyP. juliflora) were thornless, had erect habit and were non-browsed by goats, unlike other thornlessProsopis alba families from South America. Scions from the 5 tallest spineless and most erect trees were transported from Haiti to Texas A&I University where they were successfully grafted ontoP. alba rootstock. These scions should have great potential for grafting onto existing weedyProsopis and for grafting onto rootstock previously shown to tolerate salinities of seawater and pH values of 10.3.     

Provenance variation in growth characters of four subtropical pine species planted in Mexico

In 1995 a species/provenance test was established in the state of Puebla, Mexico to assess and compare the growth of Pinus greggii var. australis, P. maximinoi, P. patula and P. tecunumanii, including 10, 5, 11 and 4 provenances of each species, respectively. Each provenance test lot consisted of seed from 7 to 10 individual trees collected in natural stands. Range-wide samples were included in the test for P. greggii var. australis and P. patula. Material of P. maximinoi and P. tecunumanii from Guatemala, Honduras and Nicaragua, as well as Mexico was established in the test. The test site is in a mountainous area at 1440m elevation, near 20°N latitude. At 5 years of age significant differences were seen at both the species and provenance levels in survival, total height, diameter and volume. The overall test survival was 93%. Variance among species was three time greater than among provenances, comprising 25–33% of the total variation. P. maximinoi had the greatest height, diameter and volume (62dm³) followed by P. tecunumanii (53dm³). P. greggii var. australis had an average volume of 43dm³ and P. patula produced 30dm³. Although P. maximinoi had the lowest survival rate, the San Jeronimo provenance was the most productive of all 30 provenances tested; 98% survival and 73dm³ volume. This was equivalent to 2.8cm annual diameter increment and 2m in height growth per year. Significant growth differences among provenances within species indicate that potential gain exists using provenance selection.     

青海云杉自由授粉家系遗传评价与选择

[目的]通过对青海云杉1代无性系种子园自由授粉家系开展遗传评价,利用遗传测定结果提升青海云杉造林的良种化水平及提高良种使用率。[方法]本文以青海云杉初级种子园自由授粉家系测定林为研究材料,对13年生青海云杉家系树高、新梢长、保存率和11年生的主、侧梢冻害率进行了遗传评价,采用综合指数选择优良家系和最佳线性无偏预测方法预测单株育种值选择二代优树。[结果]研究结果表明:家系13年生的树高、新梢长、保存率和11年生主、侧梢冻害率的表型变异系数是24. 06%84%,遗传变异系数是3. 28%19. 31%。家系、家系和区组互作效应显著影响了13年生青海云杉树高和新梢长。树高和新梢长的家系遗传力分别是42. 5%和34. 2%,而单株遗传力是3. 00%,家系遗传力高于单株遗传力。采用综合指数选择法进行生长和抗性性状的综合选择,根据综合指数基于多样性和遗传增益进行平衡选择,有21个家系入选,入选家系的树高、保存率、主梢冻害率现实遗传增益分别为5. 66%、12. 59%和12. 96%。根据家系内单株13年生的树高育种值从1 103个单株中选择二代优树111个,单株入选率为10. 06%,入选二代优树树高的期望遗传增益是20. 10%。[结论]青海云杉13年生树高和新梢长在家系间存在显著变异,且还受家系与环境互作效应的影响,说明青海云杉家系的生长不仅受遗传的控制,还受遗传和环境的互作影响。根据各家系13年生树高和保存率和11年生主、侧梢冻害率综合指数值按35%的入选率综合选择21个家系,入选的家系不仅生长好,且抗性能力强,可用于回选优良无性系用于改扩建1代种子园或建立1. 5代种子园。     

Growth and yield modelling of <Emphasis Type="Italic">Acacia mangium</Emphasis> in Colombia

To study the growth and yield of Acacia mangium in the Caribbean region of Colombia, allometric equations of total volume and aboveground plus coarse roots biomass were fitted as a function of the tree’s diameter at breast height (dbh). The von Bertalanffy’s growth model and 59, 0.1 ha plots (0.55–9.55 years old) were used to develop site index (SI) curves at 6 years base age. Then, using the state-space approach, stand growth and yield models were developed for basal area, volume and biomass. The results show that A. mangium is a very promising species for timber production, atmospheric carbon removal and soil restoration because it grows very fast even in mining degraded soils. On average sites it reaches 15 m in height in 3 years. However, early and reiterated thinning coupled with initial mortality by cattle invasion of the very young understocked plantations are producing relatively low yields.     

Realized genetic gains observed in second generation seedling seed orchards of Eucalyptus pellita in Indonesia

The first generation genetic gains in four second-generation seedling seed orchards of Eucalyptus pellita established at two locations in Indonesia (Kalimantan and Sumatra) were examined by analyzing data on the height, diameter and stem form of the trees during years 1 to 3. The seed orchards each consisted of 60 open-pollinated families: 48–49 families from first-generation plus trees (improved population) and 11–12 families from natural forest (unimproved population). The realized gains for height and diameter were ca. 16 and 19%, respectively. These gains were highly significant and consistent, irrespective of age and location. However, the gains in stem form were much lower (4%) in Kalimantan than in Sumatra (21%) and only significant in the latter, possibly because of the more intensive silvicultural management regimes at the Sumatran sites. The results confirmed that the first-generation tree improvement program for E. pellita has been effective in Indonesia, and that it should provide improved seeds for operational plantation, thus raising their productivity.     

Predicting individual breeding values and making forward selections from open-pollinated progeny test trials for seed orchard establishment of interior Lodgepole Pine (<Emphasis Type="Italic">Pinus contorta</Emphasis> ssp. <Emphasis Type="Italic">latifolia</Emphasis>) in British Columbia

Ten-year height data from three open-pollinated lodgepole pine progeny test trials were analysed in order to select individuals for seed orchard establishment in the low and high elevation seed-planning units (TOLO and TOHI) of the new Thompson Okanagan seed planning-zone in interior British Columbia, Canada. The total test population had about 35,000 individuals from 362 families of 9 provenances and was divided into two portions, each serving as the base population for its appropriate seed-planning unit. For each population, various genetic parameters were estimated and individual breeding values were predicted. Combined-site estimates of individual, family, and within-family heritability ranged from 0.23 to 0.38, 0.77 to 0.84, and 0.17 to 0.29, respectively. Estimated coefficients of type-b genetic correlation were greater than 0.81, indicating little G × E interaction in this region. Provenance effects were large. Larch Hills and Inonoaklin River were the two superior provenances with an expected gain of 13% and 10% in stem volume at rotation age of 60 years in TOLO. Individual breeding values was not uniformly distributed among provenances and the top 100 individuals originated from 20 families in TOLO and 32 families in TOHI. Co-ancestry among these individuals should not be a serious concern in seed orchard establishment as the predicted genetic loss due to excessive inbreeding is only 1.06% in TOLO and 0.6% in TOHI. The status numbers of the two prospective seed orchards are 32 and 44, respectively, and both are well above the required minimum of 10 in British Columbia. Using unrelated clones for seed orchard establishment may result in reduced optimum genetic gain and thus is not a favourable option.     

Tamarack and Black Spruce Growth on a Boreal Fen in Central Alberta 9 Years after Drainage

Tree growth was measured before, and 9 years after draining a boreal fen that supported a 50- to 60-year-old stand of tamarack (Larix laricina (Du Roi) K. Koch) and black spruce (Picea mariana (Mill.) B.S.P.). Treatments consisted of a series of ditches spaced 30, 40 or 50 m apart, and an undrained control. Nine years after drainage, the diameter, height, basal area, and volume growth of tamarack had increased by 2–5 times that on the control site. Black spruce growth on the drained site was 1.6–5 times that on the control. Tamarack average volume growth (1.20 m³ ha⁻¹ year⁻¹) on the drained site was superior to that of black spruce (0.21 m³ ha⁻¹ year⁻¹). In general for both species, there were no significant differences in growth between trees on the different ditch spacings. This result was attributed to the water table being low enough that adequate aeration zones existed across the strips between ditches on all spacings. Regeneration after treatment was greater on the drained than on the control plots, particularly in the disturbed areas near the ditches where new tamarack seedlings reached densities between 9400 and 12,000 stems ha⁻¹. There was no relationship between increased tree growth and tree distance from the ditches for both species, probably because the water table had been lowered sufficiently so that inadequate substrate aeration was no longer a limiting factor.     

Genetic parameters and expected gains from selection for monoterpene yields in Petford Eucalyptus camaldulensis

Genetic parameters were estimated for yield of 1,8-cineole and total monoterpenes as a fraction of leaf weight in nineteen open-pollinated families of Petford origin at 3.75 years in two progeny/provenance trials of E. camaldulensis in Zimbabwe. Both traits appear to be highly heritable and, as expected, were strongly genetically correlated, with narrow-sense individual heritabilities near 0.50. Expected gain in the first generation following individual selection in the trials of one tree in 10 for either trait is about 25–32%.Genetic correlations between growth traits and 1,8-cineole yield were small. This indicates that both traits might be improved concurrently thus enhancing the economics of growing Petford E. camaldulensis for wood and medicinal oil. However, the presence of moderate and unfavourable genetic correlations between growth traits and total yield of monoterpenes warrants further study. It was not possible to gauge the significance of apparent family × site interaction for 1,8-cineole yield in this study. However, a test of rank correlation showed an association (Ip<0.01) between family rankings on each site and the highest-yielding trees on both sites came from the same families. This raises the possibility of being able to select individuals for cloning that yield well over a range of site conditions.     

Genetic characterisation of a Eucalyptus nitens base breeding population in South Africa

The measurement and statistical analysis of data from eight Eucalyptus nitens trials, established in the summer rainfall forestry region of South Africa during the 1980s and 1990s, have enabled the characterisation of the Institute for Commercial Forestry Research's breeding population. Provenance testing showed that the more northerly New South Wales (Australia) Eucalyptus nitens provenances of Barren Mountain and Barrington Tops are distinctly better suited to the summer rainfall areas of South Africa than the southern New South Wales provenances and the Victorian provenance, Penny Saddle. Generally, the species was not badly affected by Coniothyrium canker. High type B genetic correlations for all site pairs, except one comparison, ranged from 0.75 to 0.99 for diameter at breast height (dbh), indicating very little or no genotype × environment interaction for dbh for the genotypes tested in this study. Narrow-sense heritability coefficients ranged from 0.01 to 0.34, indicating that the species generally exhibited sufficient breeding opportunity for improvement of diameter growth. High genetic correlations of greater than 0.90 between diameter measurements at 52 to 62 months after establishment and diameter measurements at 94 or 113 months were found, indicating that selections can be reliably made at five or six years. Predicted genetic gains were highest in the trials at Goedehoop and Arthur's Seat, with increases in dbh of 3.07 cm (17.1%) and 3.17 cm (20.7%), respectively, at full rotation.     

Factors influencing the formation of heartwood discolouration in sycamore (<Emphasis Type="Italic">Acer pseudoplatanus</Emphasis> L.)

Sycamore (Acer pseudoplatanus L.) is a tree species with highly valuable wood. Similar to European beech (Fagus sylvatica L.), the stemwood of sycamore can be devalued due to the discolouration i.e. brown heart (hearwood discolouration, hereafter). This paper aims to establish the influence of tree traits and site characteristics on the formation of heartwood discolouration and the possibility of predicting the occurrence of heartwood discolouration. For this purpose, 351 sycamore trees from 38 sites in Slovenia, most of them on carbonate bedrock and in the mountain vegetation belt, were analysed. Stem analysis was carried out on all the trees and the age, diameter at breast height (dbh), height of crown base, forking and crown size, were established. On the stump and upper fronts of the first and second logs, the maximum heartwood discolouration diameter was measured. Using logistic regression, the positive influence of age, relative crown length and average diameter increment on the formation of heartwood discolouration was ascertained. Conversely, the probability of heartwood discolouration was diminished by diameter increment in the last 20 years. In the less productive sites, the probability of formation of heartwood discolouration was relatively high in small diameter trees, but it increased slowly with diameter. Tree forking also contributed to a large extent of the heartwood discolouration. After the diameter at breast height achieves 45 cm, the formation of heartwood discolouration on the first log is highly probable. As in beech, the heartwood discolouration increases along the stem axis up to a height of 6–8 m, and decreases in the higher parts of the tree.     

Provenance and family variability in slash pine (Pinus elliottii var. elliottii Engelm.) grown in southern Brazil and northeastern Argentina

A total of 172 seed orchard open-pollinated families of slash pine (Pinus elliottii var. elliottii Engelm.), generallysuperior for growth in the southeastern United States, wereevaluated in southern Brazil and northeastern Argentina. Mostfamilies were from selections originally made in four majorphysiographic regions within the species' natural distribution:Atlantic Coastal Flatwoods, East-Central Florida Flatwoods, GulfCoastal Flatwoods, and Southern Coastal Plain (withoutflatwoods). Ninety-one families were established in 1982 inthree tests in the Brazilian states of Santa Catarina and Parana. In 1986, 119 families, including 35 common to the Braziliantests, were planted in four tests in Corrientes and Misionesstates in Argentina. Variation among provenances for individualvolume growth was significant for both countries withEast-Central Florida Flatwoods consistently having the highestmean age-eight year volume and Southern Coastal Plainconsistently the lowest. Heritabilities were 0.20 in Argentinaand 0.44 in Brazil with within country type B geneticcorrelations of 0.66 and 1.00 for age-eight individual volume,respectively. The between country type B genetic correlation was0.63. Type B genetic correlations between United States breedingvalues for age-fifteen volume and Argentinian and Brazilianbreeding values for age-eight volume were 0.10 and 0.15,respectively. Families were generally superior to local checksin both South American countries.     

Trait variations in 28-year-old teak (Tectona grandis) provenance field trials in Ghana,West Africa

Stem straightness, axis persistence, presence/absence of protuberant buds and epicormics, diameter and height have profound influence on timber quality and volume of teak (Tectona grandis). Provenance trials of teak were established in the 1970s in Ghana, as part of the Food and Agriculture Organization (FAO) International Series of Provenance Trials, with the view of selecting teak germplasm for sites with specific environmental conditions. Two field trials were located in dry semi-deciduous (dry) and moist semi-deciduous (moist) ecological zones of Ghana. They consisted of 13 provenances, including four landraces each from Ghana and Indonesia, and two and three provenances from India and Laos, respectively. Trees were assessed at 9, 17 and 28 years to (1) quantify the potential variation in quality and timber volume production, (2) examine possibilities for determining early selection of parameters of superior provenances and (3) select provenances for sites with particular environmental conditions. Production traits were higher on the moist site than the dry site. Mean height was 23.2 and 20.2 m tree^?1, stem cross-sectional area at breast height was 0.0896 and 0.0474 m² tree^?1, and stem volume was 0.75 and 0.34 m³ tree^?1 for the moist and dry sites, respectively. Nilambur provenance from moist India had the highest mean stem straightness score of 19% above average, whereas Savannakhet from Laos had the best protuberant bud score with 18% of the trees above average. Indonesian landraces performed better in the dry zone, whereas provenances from India and Laos performed better in the moist zone. Phenotypic correlations between age 9 and 28 years were moderate (r 0.54–0.90) to high (r > 0.90) for production and qualitative characteristics, indicating feasibility of early assessment for identification of superior provenances. Nilambur and Savannakhet II provenances proved to be favourable choices for the moist zone, whereas the Temandsang provenance from Indonesia was found to be the best choice for the dry site.     

基于树高和树冠因子的立木材积模型研究

[目的]由于激光雷达技术已经能准确测定立木树高及相关树冠因子,应用该技术建立基于树高和树冠因子的立木材积模型,为激光技术在森林蓄积估计中提供技术支撑.[方法]利用云杉、冷杉、栎树、桦树4个树种组的3 010株实测样木数据,分析了立木材积与胸径、树高、树冠因子之间的相关关系;并通过对数回归方法构建了基于树高和树冠因子的立木材积模型,用确定系数R²和平均预估误差MPE等6项指标对模型进行评价.[结果]表明,立木材积与单一因子之间的相关,以胸径最为紧密,其次是树高,再次是冠长和冠幅.基于树高和树冠因子的立木材积模型中,以树高和冠幅作为解释变量的二元模型效果较好,再增加冠长因子的三元模型改进不大.云杉、冷杉、栎树、桦树4个树种组基于树高冠幅的立木材积模型,其R²分别为0.81、0.80、0.76和0.77,MPE分别为4.7%、5.3%、5.4%和5.3%,模型预估精度均能达到95%左右.[结论]本文对材积与林木因子之间相关关系的定量分析,建立了云杉、冷杉、栎树、桦树4个树种的立木材积模型,模型预估精度高.为激光雷达技术定量估测森林参数提供了依据.     

丝栗栲林生长与生产力的研究

在福建省邵武市洪墩采育场，调查丝栗栲林标地１０块，做平均木、树干解析木９株，杉木人工林标地２块，研究丝栗栲的生长与生产力，结果表明：丝栗栲林的胸径、树高及单株材积总生长量，均随年龄的增加而增加；胸径２０ａ前生长最快；树高１６ａ前生长最快；材积３６ａ时尚未有下降的趋势。胸径、树高平均生长量，随年龄增加而增加，当生长量达高峰后，则随年龄的增加而下降；胸径生长高峰，好立地１２ａ，中、劣立地１５ａ；树高生长高峰，好立地１０ａ，中立地８ａ，劣立地１２ａ；材积平均生长量，随年龄增加而增加，好、劣立地３６ａ时仍未下降，中立地３４ａ时生长量最大。胸径、树高连年生长量随年龄增加而下降；材积连年生长量，随年龄增加而增加，当生长量达高峰后，则随年龄增加而下降，生长高峰出现的年龄，好立地２８ａ，中立地２２ａ，劣立地２６ａ。在相似的立地条件下，丝栗栲林的蓄积量比杉木人工林低，但乔木层总生物量比杉木林高。