林龄、采伐方式对大叶相思萌芽更新的影响*

在海南省琼海县进行了不同林龄、不同采伐方式对大叶相思萌芽更新影响的研究，同时比较了保留不同萌条数量的萌芽林生长表现。结果表明：（１）林龄对伐桩萌芽率没有显著影响，但对伐桩存活率及萌条的径、高生长影响显著或极显著。林龄越大，萌芽更新效果越差；（２）皆伐和隔行采伐对大叶相思伐桩的萌芽率、萌条数量和存活率均无显著影响，但对萌条的径、高生长影响极显著。试验证明对大叶相思林分施以隔行采伐通过萌芽更新建立复层     

不同轮伐期和重复采收对大叶相思萌芽更新和林分产量的影响*

不同轮伐期和不同林分密度以及不同轮伐期组合和重复采收对大叶相思萌芽更新和林分产量影响的研究结果表明：①轮伐期对伐桩的萌芽力没有显著影响，但对萌芽林的生长有显著或极显著影响；林分密度对伐桩萌芽力和萌芽林生长均无显著影响。林分的材积和生物量总产量（种植后８ａ）随轮伐期的延长而减少。研究证明，大叶相思实生林萌芽更新的首采轮伐期以４ａ为最佳。②矮林作业能在一定程度上使大叶相思幼态化。在种植后５～６ａ内对这一树种进行第二次采伐的更新效果与第一次采伐的更新效果之间没有显著差异。对于以９ａ为一个经营期来说，以萌芽更新方式经营２代与３代其更新效果和林分总产量相当。为减少营林成本提高经济效益，建议经营两代即可，轮伐期组合以４＋５为最佳。     

采伐季节 伐桩直径 桩高及树龄对刺槐萌芽更新的影响

在河北省灵寿县进行了采伐季节、伐桩直径、桩高及树龄对刺槐当年萌芽更新效果影响的初步研究。结果表明:①非生长季采伐的萌芽更新效果明显优于生长季节内采伐,即前者的萌条数量、萌条径高生长及生物量显著高于后者;②伐桩直径对萌条数及伐桩萌条总生物量有显著影响,而各径级伐桩萌条的径高生长差异不显著;③在6～15a生的年龄范围内或伐桩高度低于30cm时,伐桩萌芽力是均等的,即树龄和桩高对伐桩的萌芽更新没有显著影响。     

热带薪材树种萌芽更新的研究

对15个热带薪材树种进行萌芽更新研究的结果表明,刚果12号桉、雷林1号桉、斑皮桉、细叶桉、伞房花桉、柠檬桉、托里桉、马占相思和大叶相思萌芽更新效果好。伐桩萌芽率达95—100%,伐后3年存活率在75%以上;萌条生长迅速,年平均径、高生长分别为1.43—2.10厘米和2.04—3.10米;萌芽林生物产量高,地上部分(不含伐桩)年均鲜重12.17—107.24吨/公顷。适于以矮林作业方式经营其薪材林。     

热带薪材林经营技术的研究

根据多年对热带薪材林经营管理及林分采伐更新等的研究，总结了一整套经营技术，包括抹芽定株（保留２～３株／桩萌条）、追肥（复合肥３００ｇ／株）、采收更新的轮伐期（一般４ａ左右，超短轮伐期１．５～２ａ，桉树类与相思类树种的混交林约３年采收相思类树种）、采伐方式（短轮伐期薪材林皆伐、乔薪结合择伐或间伐）、采伐季节（避开雨季，最好时期为冬季，其次为夏季）、伐桩高度（桉树类约１０ｃｍ、相思类约６０ｃｍ高）以及其它与更新相关的林龄、桩径、树种等技术问题。     

不同林地清理方式对杉木萌芽更新的影响研究

在杉木林采伐迹地上进行不同林地清理方式对杉木萌芽更新影响的定位研究。结果表明：炼山清理迹地能提高萌条数量而且能促进萌条生长，提高萌条质量，并对伐桩的萌条分布也有一定影响，采伐时应尽量降低伐桩高度，并正确留条。     

不同伐桩直径及高度对马占相思萌芽更新影响的研究*

对速生多用途树民占相思进行了不同伐桩高度（25cm,50cm,75cm和100cm)及不直径（4．1－8．0cm和8．1－12．0cm)萌芽更新影响的研究，结果表明，伐桩的萌芽率及平均萌条数随伐桩高度的增加而增加，随直径的增大而减少，萌条直径，长度及直萌条（可望生长成材之萌条）总断面积随伐桩的高低和大小而增减，伐桩最低的萌芽率比以往的结果高4倍以上，以短轮伐期经营的马占相思人工林，采用50－75cm伐桩高度萌芽更新效果好。     

不同密度4年生大叶相思萌芽更新试验

不同密度4年生大叶相思更新试验,经3年萌芽生长观测,结果表明:不同密度3年生的萌芽林与原林分(未更新的林分,下同)径、高生长相接近,而材积和生物量(鲜重,下同)生长,萌芽林则比原林分分别增长3.11 m~3/ha和6.31 t/ha。且萌芽林林分材积和生物量生长均比原林分同期生长量(3年)显著提高,1.0m×1.5m 密度的林分材积和生物量分别提高44.7％和133.8％,1.0m×2.0m 的分别提高40.8％和63.9％,1.5m×1.5m 的分别提高43.0％和80.6％。作为薪炭林经营的大叶相思造林密度以1.0m×1.5m为宜,并且4年生时采伐更新其萌芽率和萌芽条数最高,分别达到93.9％和平均每桩萌条11.6条。     

热带薪材林经营技术的研究

根据多年对热带薪材林经营管理及林分采伐更新等的研究,总结了一整套经营技术,包括抹芽定株(保留2～3株/桩萌条)、追肥(复合肥300g/株)、采收更新的轮伐期(一般4a左右,超短轮伐期1.5～2a,桉树类与相思类树种的混交林约3年采收相思类树种)、采伐方式(短轮伐期薪材林皆伐、乔薪结合择伐或间伐)、采伐季节(避开雨季,最好时期为冬季,其次为夏季)、伐桩高度(桉树类约10cm、相思类约60cm高)以及其它与更新相关的林龄、桩径、树种等技术问题。     

伐桩高度对尾巨桉萌芽更新的影响

通过对尾巨桉3个不同高度水平伐桩的萌芽率和萌芽力的调查分析,阐明伐桩高度对尾巨桉萌芽更新的影响。结果表明：尾巨桉的萌芽更新能力极强,且高度在5～10 cm的伐桩在3个处理中具有最高的萌芽率和萌芽力,其中,萌芽率高达97.3%,显著高于15～20 cm的伐桩;萌芽力高达16条/桩以上,且与10～15 cm和15～20 cm的伐桩存在极显著差异;不同处理对萌芽林胸径和树高的生长没有显著性影响。     

Early regeneration of Fraxinus rhynchophylla in the understorey of Larix kaempferi stands in response to thinning

The effects of thinning were investigated on naturally regeneratedFraxinus rhynchophylla Hance (Korean ash) grown in the understoreyof a Larix kaempferi (Lamb.) Carr. plantation, established ona site that previously supported old growth hardwood forests.The regeneration characteristics were evaluated after thinningof the plantation (about 60 per cent of relative density wasremoved). In the naturally regenerated and mixed stands, Quercusmongolica Fisch. was the most abundant tree species in the overstorey,but the understorey of the thinned plantations was dominatedby F. rhynchophylla with six other minor tree species. Fraxinusrhynchophylla was regenerated by four propagation types includingnatural seedling, stump sprout, root sprout and layering. Beforethinning, the difference of average height growth for each regenerationtype was insignificant. One year after thinning, the stump sproutsshowed the fastest growth among the regeneration types. Heightgrowth of advance regeneration was slow in the year followingthinning but then increased rapidly surpassing the other regenerationtypes 5 years after thinning. Thinning had an effect on thecomposition of regenerated trees also by seedling, stump sprout,root sprout and layering in the understorey. Advance regenerationsoccupied the upper understorey at 5 years after thinning. Alarge number of stump sprouts emerged in the plots 1 year afterthinning, while at 5 years after thinning the occupation ofstump sprouts decreased. Root sprouts and layers faded away.Considering the early growth and the composition of understoreyF. rhynchophylla, its advance regeneration has a high potentialto develop into overstorey trees at this site.     

Influence of thinning time and density on sprout development, biomass production and energy stocks of sawtooth oak stumps

The high potential values of sawtooth oak (Quercus acutissima) in fuelwood or bioenergy are recognized. Sprouting ability, sprout growth, biomass production and energy stocks in coppiced plantations of sawtooth oak were evaluated at the Hongya Mountain Forest Farm in Anhui Province, China. Experimental treatments applied in a split-plot design included three sprout thinning times and four sprout numbers reserved on each stump (1 sprout, 2 sprouts, 4 sprouts stump⁻¹ and check). Sprout growth and biomass production per stump were significantly affected by the treatments and a significant positive relationship between stump basal diameter and sprout numbers produced was observed. After the third growing season, the highest total sprout biomass per stump was achieved in the treatment with thinning excess sprouts at the end of first growing season (December, 2007) and reserving 4 dominant sprouts per stump (T12S4, reaching 8.67 kg stump⁻¹), while the lowest was found in the treatment with thinning the sprouts in August of the first growing season and reserving 1 dominant sprout per stump (T8S1, only 3.40 kg stump⁻¹). Different treatments also influenced gross calorific values (GCV) of the components sampled from 3-year-old sprouts and the mean GCV of stem wood on an oven-dry weight basis was within the range of 18.45 ± 0.15 and 18.83 ± 0.12 kJ g⁻¹. Similar to the sprout biomass production, the greatest total and stem energy stocks per stump were observed in T12S4 treatment, achieving 161.6 and 110.5 MJ stump⁻¹, respectively. Based on the results from this study, thinning excess sprouts to reserve 4 sprouts per stump as early as age 1 could be proposed for the management of sawtooth oak coppice with cutting cycle of 3-5 years and stand density of 5000-6000 stump ha⁻¹.     

辽东栎伐桩萌苗的发育规律

通过对黄土高原黄龙山林区辽东栎林固定样地连续6年的调查,研究间伐强度分别为13.4％(弱度间伐)和30.0％(强度间伐)的辽东栎伐桩萌苗的存活与生长规律.结果表明:1)间伐第1年,辽东栎伐桩均有萌生枝发生,每桩萌生枝数量和萌生枝高度在不同强度间无显著差异;2)萌生枝数量受伐桩高度和直径的影响,当伐桩高度较低时,萌生枝数量随伐桩高度的增加而增加,超过20cm后随之减少,呈三次抛物线关系;伐桩萌生枝数量随着伐桩直径增加呈现先增加后减少的趋势,直径30～50cm的伐桩萌生枝数量最多;3)伐桩萌生枝数量与最长萌生枝高度呈显著线性负相关,存在“萌生枝数量——高度权衡”现象;4)间伐第6年,伐桩的存活率为97.01％,强度间伐区萌生枝高度显著高于弱度间伐区;5)调查期间,辽东栎伐桩萌生枝数量逐年下降,伐桩产生的萌生枝数量越多,后期萌生枝死亡的数量也越多,表明伐桩能够自我稀疏,存在“萌代主”现象.在黄土高原地区,辽东栎伐桩萌芽潜力很大,应合理利用;间伐时伐桩高度应尽量低于20cm;伐桩直径在30～50cm更有利于其无性更新;间伐后伐桩应及时除蘖定株,促进萌生枝生长;间伐强度30.0％(强度间伐)更有利于辽东栎伐桩萌生枝的生长.     

Survival and development of Liaodong oak stump sprouts in the Huanglong Mountains of China six years after three partial harvests

The survival and development of Liaodong oak (Quercus liaotungensis Koidz) stump sprouts were studied for 6 years under leave-tree, as well as 60 and 75% crown closure uniform shelterwood in the Huanglong Mountains of China. Stump sprout survival rate, number of sprouts, and sprout height under the three partial harvests during the first year post-harvest did not differ. Six years post-harvest, 78.32% of the stumps had living sprouts. No variation in sprout survival was found among the treatments throughout the study period. The number of living sprouts per stump was 13.77 ± 0.50 in the first growing season after harvest, and dropped to 6.49 ± 0.22 after 6 years. This result indicated the occurrence of self-thinning within the sprout clumps. Moreover, the height of dominant sprout increased from 52.88 ± 1.62 cm (in the first year) to 132.82 ± 2.35 cm (in the sixth year) post-harvest. Sprout height in the leave-tree harvest type was higher than those in the two shelterwoods in the fifth and sixth years after logging. Annual height growth was approximately 8–96 cm during the first growing season, and then decreased at a rate of 1–44 cm per year in the following years. A negative relationship was found between sprout height and the number of sprouts per stump. This result indicated a trade-off between the number of sprouts and height growth. The number of sprouts per stump decreased by about 0.2 stem for each 1 m²/ha increased in residual basal area. Therefore, sprouting may play an important role in the restoration of the secondary forest after harvesting.     

Sprouting ability of two‐year‐old Betula pendula stumps exposed to different light intensities during five years

Altogether 1 080 two‐year‐old silver birch (Betula pendula Roth) were planted in groups of 36 plants at aspacing of 20 x 20 Cm in spring 1983 on a nursery field at lat. 60° 15 N and long. 16°00 E. In spring 1984 all plants were cut with 10 cm high stumps and light screens were arranged on the stump groups. Relative ¡rradiance (RI) 5, 10, 25, 50, 75 and 100% of full sunlight were used. After five growing seasons, all stumps exposed to 5 or 10% light intensity were dead, and 64–94% of stumps exposed to 25–100% RI were alive. 1.3–1.4 sprouts per living stump were living five years after cutting. The mean height of sprouts was highest on stumps exposed to 100% light. Also dry weights of leaves and sprouts, number of leaves per sprout, and leaf area were highest on stumps exposed to full sunlight. Stumps producting only one sprout five years after cutting have higher height and dry weight values than stumps with more sprouts. The biomass production per hectare and year for silver birch sprouts at a spacing of 0.2 m and with 90% survival was calculated as 5.4 tonnes. The biomass of leaves was 8.1 tonnes/ha/year five years after cutting.     

Cherrybark oak stump sprout survival and development five years following plantation thinning in the lower Mississippi alluvial valley,USA

Cherrybark oak (Quercus pagoda Raf.) stump sprouts were studied for 5 years in a 30-year-old plantation thinned to 70–75% stocking (light thinning) and 45–50% stocking (heavy thinning). Sprouting success, survival, number of sprouts per stump, and sprout height differed little between thinning treatments throughout the 5-year study period. Pre-harvest tree d.b.h. also had no influence on sprout survival and development. A 2-year drought reduced survival and may have influenced sprout development. Sprout clump survival dropped from 90% 1 year following thinning to 46% 3 years after thinning. Although sprout height averaged 337 cm 5 years after thinning, annual sprout growth decreased from 166 cm the first year after thinning to 33 cm in each of the last 2 growing seasons. Results indicated that bottomland hardwood regeneration evaluation models may underestimate the potential of oak stump sprouts to contribute to pre-harvest regeneration assessments. Further study in the role of stump sprouts to regenerate bottomland oak species is needed. The U.S. Government's right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged     

印度阿鲁纳恰尔邦温带阔叶混交林树桩周长和高度对受干扰的树形杜鹃再发芽的影响

Sprout contribution to natural regeneration of Rhododendron arboreum following the tree felling for fuel wood and other purposes was studied in two disturbed sites (Paipraw and Falockchar) of Rhododendron forest in Arunachal Pradesh, northeast India. Cut stumps were categorized into seven girth and height classes to evaluate the effect of stump girth and height on production of sprouts. Effect of stump girth on survival of sprouts was also investigated. Results show that highest number of cut stumps is recorded in medium girth classes (50–80, 80–110, and 110–140 cm) in both Paipraw and Falockchar stands. However, density of cut stumps is higher in Paipraw (1 210 stumps·ha⁻¹) than Falockchar (1 154 stumps·ha⁻¹). Nevertheless, a little higher percentage of sprouting is recorded in Falockchar (18%) than that of Paipraw (15%). Similarly, maximum number of cut stumps is observed in the medium height classes (50–80, 80–110 and 110–140 cm) in both the sites. Cut stumps with lower girths show greater ability of sprouting than that of larger girth classes. Significant correlations are observed between stump girth and sprout number and between stump height and number of sprouts. Survival of sprouts also depends on stump girth. Survival of sprout shows significant variations between different sampling times in both the sites. Though overall sprout regeneration of R. arboreum is very poor, sprouts arising from lower girth classes survive well than those of higher girth classes. The findings of this investigation signify that stump sprouting is not playing much role in the natural regeneration of R. arboreum though it has the ability to sprout. Sprout survival is not adequate to restore a stand where indiscriminate tree felling is continued and the species may be considered as a poor coppicer. Therefore, regeneration through seeds and seedlings should be preferred over regeneration through sprouting.     

Effects of thermal wounding, shading and exogenous auxin on some sprouting responses of coast redwood seedlings

The effects of wounding, shading, and indole-3-acetic acid (IAA) on sprouting responses were examined in coast redwood (Sequoia sempervirens D. Don (Endl)) seedlings. In August, two-year-old seedlings were given one of three thermal wounding treatments made with a blowtorch at the stem base. After 8 months, the heat-wounded seedlings were decapitated above the burl and IAA (0.00% to 1.00% by weight in lanolin) was applied to the cut surface every week for 8 weeks. Throughout the 8-week hormone treatment, the decapitated seedlings were subjected to one of three shading treatments (no shade, 70% shading and complete darkness). At the beginning of June, sprouts were harvested from each stump and measurements made of the length of the tallest sprout, number of sprouts, dry weight of all sprouts, and mean dry weight per sprout. All sprouting parameters showed negative responses to IAA. Shading decreased sprout number and sprout dry weight. Wounding increased maximum sprout length and dry weight per sprout but decreased the number of sprouts. Only the 2-way interaction between IAA and wounding was not significant for any of the responses.