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1.
本文定量的研究四川省攀枝花——西昌地区不同林型的云南松林地上部分生物量及云南松林各层次可燃物的数量、类型及热值分布规律等。研究结果表明:云南松林地上部分可燃物总量为95.043t/ha,其中乔木层77.914t/ha,灌木层4.164t/ha,草本层0.104t/ha,凋落层12.860t/ha。测定了12种可燃物的发热量。计算出不同林型的云南松林燃烧时潜在能量为:草类——云南松林177.57×10~(10)J/ha,灌木——云南松林154.56×10~(10)J/ha,常绿栎类——云南松林167.63×10~(10)J/ha,落叶栎类——云南松林158.74×10~(10)J/ha,旱冬瓜——云南松林170.57×10~(10)J/ha。 相似文献
2.
By means of calorimetry measurement,the caloric values of various components,the standing crop of energy,not energy production and energy conversing efficiency of an artifi-cial dahurian larch community at Laoshan Plantation Experimental Station of Maoer Shan For-est Farm in the eastern part of northeast China were determined and studied in the present paper.The result of the experiment were as follows:(1)caloric value varied with plant species and plant organs,in general,the order of caloric value was tree,shrub and herb,and for different organs,was leaf, branch,trunk(stem),bark and root.(2)The standing crop of energy of larch community and tree layer were 269.719×10~(10)J/ha.and 264.440×10~10J/ha.respectively.Theree xisted different distributions of energy in various components and different layers.(3)Net ener-gy prduction of larch community and its tree layer were 264.346×10~8J/ha.a and 243.678×10~8J/ha.a respectively.To the photosythetical active radiation on the stand,its energy con-versing eff 相似文献
3.
林冠截留对杉木人工林生态系统物质循环的影响 总被引：2，自引：1，他引：2
根据1999-2002年连续4年的观测数据,对林冠截留在杉木林生态系统物质循环中的作用进行研究.结果表明:每年林冠截留降雨量267.0 mm; 林冠截留蒸发散量占杉木人工林总蒸发散量的27.2%,林冠截留水分的物理蒸发量占杉木林集水区水分输出的18.97%;林内净降水的营养物质为143.329 kg·hm-2a-1,比冠上大气降水输入的63.924 kg·hm-2a-1多74.905 kg·hm-2a-1,增加了117.2%; 林冠截留减少了到达林地表面和入渗土壤的水分,减少了集水区地表水和土壤漏水的输出,从而减少了营养物质的输出,可见,林冠截留是系统保存营养物质的重要机制之一. 相似文献
4.
林冠截留在杉木林生态系统能量转换过程中的作用 总被引：1，自引：0，他引：1
根据会同生态站2000-2005年连续定位观测数据,研究杉木人工林林冠截留在杉木人工林生态系统能量转换过程中的作用.结果表明:林冠层每年吸收的辐射能为25.543 0亿J·m-2,透过林冠层的辐射能为2.530 6亿J·m-2,被冠层反射的辐射能为2.743 2亿J·m-2,分别占到达林冠表面辐射能的82.7%、8.2%和9.1%;林冠截留水分的蒸发,使得系统获取的净辐射能向潜热能转化.每年林冠截留水分蒸发耗能6.369 5亿J·m-2,占系统净辐射能的22.9%,占系统总蒸发散耗能的30.4%,是系统能量支出的一个重要组成部分;林冠截留使大气降水中的雨滴动能消耗在克服枝叶阻力的做功上,叶面水滴从冠层滴落下,是一个由势能转化为动能的过程;冠层叶片对水滴有汇聚作用,使冠滴水直径较冠上大气降水大,冠滴水的直径主要受冠层结构的影响,与大气降水量和降水强度的关系不大;林分郁闭度为0.9,枝下高7 m,降水量大于3 mm时,林冠层不能有效地降低雨滴动能,只有在雨量极小、林冠能截留大部分水量,或者雨强极大、直径大的雨滴在枝叶表面撞击分散的情况下,才能显示林冠对大气降水雨滴动能的降低作用. 相似文献
5.
杉木在铜仁地区用材林树种中,无论是面积还是蓄积均属首位。据1985年林业资源二类调查统计,全区有杉木人工林面积3.04×10~4ha,占全区人工用材林面积的61.84％;蓄积96.78万m~3,占全区人工用材林蓄积的71.39％。笔者通过一系列调查研究,从经营技术角度提出了该区在杉木生产发展中的一些技术措施,供生产参考。一、自然条件与生长现状1.自然条件铜仁地区海拨200～2572m,属中亚热带季风温暖湿润气候,年均气温13.4～17.5℃,年均降水量1097～1425mm,无霜期275 相似文献
6.
湖南第2代杉木幼林的水文学过程及养分动态研究 总被引：8，自引：2，他引：8
采用小集水区技术和定位研究方法 ,根据连续 3a观测所取得的数据 ,对湖南会同第 2代杉木幼林的水量平衡和养分元素的地球化学循环进行了研究。结果表明 :该森林生态系统年降雨输入为 1170 6mm ,其中 3 5 3mm以树干茎流形式进入林地 ,占降雨量的 0 3% ,林内穿透水为 10 17 3mm ,占 86 9% ,另外林冠年截留量为 149 77mm ,占年降雨量的 12 8%。以径流形式流出该系统的水量为 42 8 0 5mm ,占年降雨量的 36 5 7% ,其中地表径流和地下径流分别占总径流的 4 31%和 95 6 9%。系统另一输出形式蒸散量为 86 2 6 4mm ,为年降雨量的 6 2 2 %。在该森林生态系统中 ,由降雨输入的N、P、K、Ca、Mg等元素的总量为 5 3 173kg·hm- 2 ·a- 1 ,径流输出量为 42 5 6 3kg·hm- 2 ·a- 1 ,净积累量为 10 6 10kg·hm- 2 ·a- 1 。与稳定态的第 1代杉木林相比 ,第 2代杉木幼林的林冠截留量成倍减少 ,地表径流、地下径流量和径流总量都高于第 1代杉木林 ,其涵养水源的能力相对较弱 ,抵抗外界干扰的能力比稳定态的第 1代杉木林差。从生物循环来看 ,第 2代杉木幼林的养分存留量大 ,表明第 2代杉木幼林将从土壤中吸收的养分大量地保存在林木中 ,造成土壤中养分的逐渐减少 ,维持持久的林地生产力应引起重视。第 2代杉木幼林 相似文献
7.
章古台地区樟子松人工林水量平衡初步研究 总被引：1，自引：0，他引：1
为揭示樟子松人工林水量平衡规律,在辽宁省章古台地区,选择林龄为32 a、密度为404株/hm2的樟子松人工林,利用2 a（2010、2011）的观测结果,采用水量平衡方法对樟子松人工林的降水分配进行研究。结果表明：樟子松人工林内降水量、树干茎流量、林冠截留量分别为422.7、0.8、28.1 mm,占同期降水量的93.6%、0.2%、6.2%。樟子松蒸腾耗水量、枯落物＋林下植被＋土壤蒸散量、土壤贮水量变化量分别为116.1、287.3、20.1 mm,占同期降水量的25.7%、63.6%、4.5%;樟子松蒸腾耗水量占林地内蒸散量的28.8%,枯落物＋林下植被＋土壤蒸散量占林地内蒸散量的71.2%。 相似文献
8.
[目的]揭示杨树人工林皆伐对滩地蒸发散和产流的影响。[方法]基于涡度相关系统对长江滩地杨树人工林皆伐前后水汽通量连续3年(2010―2012年)的观测数据,通过对比皆伐前、后气候条件相似的2个时段(1整年)的蒸发散,揭示皆伐后研究区蒸发散的变化,并基于水量平衡反推研究区产流的变化。[结果]皆伐后土壤温度和水位上升,土壤表层含水量全年均值减小约0.03;研究区蒸发散皆伐前、后具有相似的日变化规律和季节动态特征,但皆伐后的全年蒸散量仅为皆伐前的66.3%;皆伐后研究区产流率(产流量/降雨量)从皆伐前的0.53上升至0.62;皆伐前、后7、8、12月的干旱指数(潜在蒸发散/降雨量)均大于1,其他时期均小于1。[结论]滩地杨树人工林皆伐后滩地蒸发散减少而产流率增加,加剧夏季干旱的可能性有所降低,但洪水爆发期间削减洪峰的能力也减弱。 相似文献
9.
通过测定杉木人工林群落的生物量和各组分的热值,探讨了该群落净初级生产的能量积累和分布.结果表明该群落能量现存量为17 553×108～15 485×108 J/hm2;各组分或器官的热值含量变化范围为17.36～21.04 kJ/g,其中以花果、凋落物和叶的能量含量较高,树干居中,而树皮、根、枝的能量含量较少;不同组分或器官的能量现存量差异较大,其大小顺序为树干＞根＞叶＞枝＞凋落物＞地被物地上部分＞地被物地下部分;群落地上部分与地下部分能量的比值为4∶1,垂直层次中能量分布按由大到小的顺序排列为乔木层＞根系层＞凋落物＞地被物;群落能量现存量的间伐损失量一般随抚育间伐强度的增大而增加,当抚育间伐强度小于50%时,损失量一般不超过能量现存量的1/3. 相似文献
10.
通过对福建建瓯25年生马尾松和杉木人工林凋落物能量归还量及月动态的研究,结果表明:马尾松和杉木人工林凋落物年能量总归还量分别为13 734 KJ.m-2和11 377 KJ.m-2,其中通过落叶归还的能量分别占总凋落物能量归还量的67%和60%,表明凋落叶是凋落物能量归还的主体。马尾松林总凋落物能量归还量月变化动态呈单峰型,在7月出现峰值;而杉木林总凋落物能量归还量1 a中出现3次峰值(5月、8月和11月)。 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