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1.
杨树新无性系冠层特性与生长关系研究 总被引：14，自引：1，他引：13
对 5年生黑杨无性系的冠层特性与材积生长之相关性进行了研究。材积生长与全树总叶面积TLA、树冠表面积TCA和冠型率CSR呈极显著正相关而与叶面积指数LAI、冠层密度CLD呈负相关。冠层内上、中层的叶面积对材积生长起了决定性作用 ,下层叶面积与材积生长关系不大。水平方向 ,冠层内、外部叶面积特性对材积生长贡献较大 ,而中部叶面积特性贡献小。阐明了杨树生长的理想冠层特性。 相似文献
2.
《中国森林病虫》2016,(4)
调查不同混交模式下降香黄檀树冠结构指标和黑痣病发病情况,分析树冠结构指标和黑痣病的关系,筛选出防控黑痣病的主要树冠结构指标。结果如下:降香黄檀黑痣病病情指数与枝下高(Hub)、叶面积指数(LAI)呈显著正相关性,与冠长树高比(PLCH)、冠幅(W)、树冠表面积(CSA)、单株叶面积总数(TLA)呈极显著负相关,一级分枝粗度(Dfb)、一级分枝角度(Afb)、冠形率(CSR)、冠层密度(CLD)与病情指数相关性不显著;树冠表面积(CSA)与病情指数相关系数最大。通径分析表明各树冠结构指标对病情指数直接作用结果如下:正向作用程度从大到小顺序为LAI、W、CSR、Dfb、Afb;负向作用程度从大到小顺序为PLCH、CLD、CSA、TLA、Hub。由决策系数可得,对黑痣病有防控作用的各树冠结构指标从大到小顺序为CLD、PLCH、LAI、Hub、W、TLA、CSR、CSA、Dfb、Afb。综合分析可得,PLCH和W对黑痣病的相对重要性适中,与病情指数呈显著负相关,与混交模式呈极显著正相关,所以选取PLCH和W作为黑痣病生态调控的主要树冠结构指标。 相似文献
3.
通过对杉木与乳源木莲混交林中二者的树高、胸径、材积的总生长量、平均生长量、连年生长量以及树高/胸径比值曲线进行比较分析,结果表明:在杉乳混交林中,杉木在树高、胸径、材积总生长量和平均生长量上,与乳源木莲相比优势始终较为明显,说明杉木在与乳源木莲的竞争中始终处于优势地位。但在17a后,杉木树高、胸径、材积连年生长量低于乳源木莲,生长开始减缓,此时应适当进行抚育间伐。 相似文献
4.
以福建省沙县15年生(13年生时间伐)和17年生(10年生时间伐)的乳源木莲-杉木中龄混交林(杉莲比为7：3)为研究对象,通过应用Ruark异速生长模型,对间伐后混交林中乳源木莲的树冠结构进行研究。结果表明,在混交条件下,不同间伐期对树冠形状有显著影响：13年生时间伐,乳源木莲树冠生长受到限制不能充分扩展,树冠形状近似抛物线形,枝长分布方式对下部层次造成遮荫,不利于乳源木莲树木的光合作用;而10年生时间伐,乳源木莲具有圆锥形树冠、较大的枝倾角和较高的叶面积指数,因此有利于树冠对光的截获,从而增加单株生物产量,有利于培育乳源木莲大径材。杉莲混交林中乳源木莲累积叶面积指数可以分别用以下模型进行估测：y(10年生时间伐)=2．6211Z^0.1318 e^0.0417z(R^2=0．9418)和y(13年生时间伐)=1．7546Z^0.6122e^-0.1411z(R^2=0．9923)。通过残差百分比检验和后验检验表明,模型拟合度较高,预测效果良好。 相似文献
5.
研究了马尾松中龄林林下生长环境及套种乳源木莲生长效应。结果表明:马尾松中龄林林下环境较低,土壤肥力较好。密度调控在1300～1500株/hm2之间,可以形成适宜种植乳源木莲的生长环境。间伐后的马尾松中龄林与不间伐马尾松林比较,林下光照强度增加40.2%,有利于早期较耐荫乳源木莲生长。但间伐土壤结构受到一定程度破坏,垒结状况变差,紧实度增加,应该采取适当经营措施,为更新树种提供适宜的生长环境。在马尾松中龄林林下栽植乳源木莲生长效应明显。间伐后套种乳源木莲(Mtk)。10年间马尾松增加量与对照(Mck)比,平均胸径、平均树高、单株立木材积分别增加45.7%、56.5%和47.9%。经方差分析和多重比较:Mtk与Mck处理间单株立木材积间差异达到极显著水平,Mjc与Mck处理间单株立木材积间差异达到显著水平。在马尾松中龄林林下栽植乳源木莲,平均胸径、平均树高分别达到5.2cm和6.3m,年平均树高、平均胸径生长量分别达到0.52m/年和0.61m/年,能够在马尾松主伐时,提前培育更新层树种,有着宽广应用前景。 相似文献
6.
对通过杉木与乳源木莲分别进行了1∶1行状混交和5∶5块状混交开展杉木与乳源木莲混交造林试验,21年生的试验林研究结果表明:杉木与乳源木莲混交提高了林分中杉木的生长量,改善了土壤结构,增强了土壤持水能力;提高了土壤肥力。杉木与乳源木莲单行混交对促进杉木生长及改善土壤理化性质的效果好于杉木与乳源木莲块状混交;该试验中杉木与乳源木莲采取单行混交为宜。 相似文献
7.
《福建林业科技》2015,(4):33-36
以广西南宁市10年生灰木莲人工林为研究对象,研究其生长过程和生物生产力特征。结果表明:110年生灰木莲人工林平均胸径(去皮)、树高、单株材积分别达到13.4 cm、12.9 m、0.0909 m3;灰木莲树高和胸径生长均以前6 a最快,随后随林龄的增长而下降;材积生长在10年生时仍未达到峰值。210年生灰木莲人工林林分生物量为104.73 t·hm-2,其中乔木层、林下植被层和凋落物层生物量依次为93.54、0.24、10.95 t·hm-2,分别占89.31%、0.23%、10.46%。林分乔木层年净生产力为11.80 t·hm-2·a-1,不同器官净生产力大小顺序为树干、树叶、树根、树枝、树皮。 相似文献
8.
乳源木莲优质干材混交培育的研究 总被引：9，自引：0，他引：9
研究证实，乳源木莲生长迅速，树干通直圆满，较少病虫害，其木材密度超过同龄的杉木，乳源木莲早期生长缓于混交树种杉木，10a生左右进入干材速生期，16a生时干材料积接近杉木的3倍。这说明通过与杉木混交可以培育优质的大径阔叶材。乳源木莲侧枝形成分叉特性显著，适时的除萌修枝方能保证高质量干材的培育。研究发现，在南方低山丘陵区。影响澌昆交乳源木莲干材生长的主要生育地因子是坡度，缓坡地土层深厚，立地条件较好，乳源木莲干材生长最大，枝下高长，生长在下坡和半阴（阳）坡的乳源木莲之高径生长有高于其它坡位和坡向的趋势。根据林分密度和杉莲比之于乳源木莲干材培育的作用机理。应适当降低混交林的初植密度和单位面积乳源木莲的株数。采用3：1或更高的杉莲比混交造林，并通过适时的间伐，以达到枝下高长，径阶大的干材培育目标。 相似文献
9.
乳源木莲生长规律的研究 总被引：13，自引：3，他引：13
本文对人工营造的乳源木莲与杉木等混交的试验林分别不同造林年度、不同立地条件、不同混交比例，设置２１块标准地，采集２３株解析木，调查了大量数据，建立数学模型，初步揭示了９年生乳源木莲树高、胸径、形数、材积、冠幅、根系、侧枝等生长规律。 相似文献
10.
杉木乳源木莲混交林林分生产力研究 总被引：4，自引：0，他引：4
10a生杉木乳源木莲 3∶1混交林林分生物量 130 37t/hm2 ,乔木层生物量 12 7 5 0t/hm2 ,比杉木纯林增加18 7%。无论杉木、乳源木莲干材比例较高 ,两树种均是优良的用材树种。混交林年均净生产量 12 75 0t/(hm2 ·a) ,林分叶面积指数 9 0 5 ,叶对树干净同化率 179 72g/(cm2 ·a)。杉木乳源木莲混交林林分生产力比杉木纯林高。 相似文献
11.
《Scandinavian Journal of Forest Research》2012,27(5):427-435
In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads. 相似文献
12.
《Scandinavian Journal of Forest Research》2012,27(3):206-217
The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage. 相似文献
13.
Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and
also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the
amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter
bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K
was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed
significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week−1 for leaves and from 0.0225 to 0.0633 week−1 for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed
during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly
between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species
provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient
enrichment capacity and slower decomposition rates which would minimize leaching losses.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
14.
《Scandinavian Journal of Forest Research》2012,27(2):118-130
The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions. 相似文献
15.
Steven Maranz Amadou Niang Antoine Kalinganire Djeneba Konaté Bocary Kaya 《Agroforestry Systems》2008,72(3):231-239
Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional
data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral
contents and B1 and B2 vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising
germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B1 88 mg 100 g−1, B2 187 mg 100 g−1, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal
diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties
to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations. 相似文献
16.
《Wood material science & engineering》2013,8(2):76-84
Abstract Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists. 相似文献
17.
Astra Zaluma Lauma Bruna Darta Klavina Natalija Burnevica Kristine Kenigsvalde Andis Lazdins Talis Gaitnieks 《Forest Pathology》2019,49(6)
Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered. 相似文献
18.
《Scandinavian Journal of Forest Research》2012,27(1):53-61
This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland. 相似文献
19.
《Scandinavian Journal of Forest Research》2012,27(1):15-27
The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions. 相似文献
20.
本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。 相似文献