Restoration of hard mast species for wildlife in Missouri using precocious flowering oak in the Missouri River floodplain, USA

Increased planting of hard mast oak species in the Lower Missouri River floodplain is critical as natural regeneration of oak along the Upper Mississippi and Lower Missouri Rivers has been limited following major flood events in 1993 and 1995. Traditional planting methods have limited success due to frequent flood events, competition from faster growing vegetation and white-tailed deer herbivory. Results of early growth response of swamp white oak (Quercus bicolor Willd.) seedlings in relation to initial acorn mass and size, and early rapid shoot growth for seedlings produced by containerized root production method (RPM™), are presented. Containerized RPM™ seedlings grown in the greenhouse under optimal conditions demonstrate that seed size had no discernable impact on first-year root or shoot size. Seedling survival for the first two years and acorn production for the first three years after outplanting are presented, comparing use of containerized RPM™ swamp white oak seedlings to nursery stock. Flood tolerant precocious RPM™ oak seedlings in the floodplain provide a source of food for acorn-consuming wildlife ten to fifteen years sooner than oaks originating from natural regeneration, direct seeding or traditional bare root planting. Compared to bare root nursery stock that produced no acorns, some RPM™ swamp white oak seedlings averaged 4.3, 5.2, and 6.3 acorns/seedling in the first three years after fall outplanting. This revised version was published online in August 2006 with corrections to the Cover Date.     

闽楠天然次生林自然更新的影响因子研究

[目的]分析闽楠天然次生林自然更新与环境因子之间的关系,为其科学经营及保护提供参考依据。[方法]以江西省吉安市闽楠天然次生林为研究对象,通过标准地调查获取数据,运用多元数量化模型I建立闽楠幼树幼苗重要值与环境因子的关系模型,采用单因素方差分析单个环境因子对闽楠幼树幼苗更新的影响。[结果]研究表明:密度(闽楠下种母树株数、郁闭度、株数密度)、坡位、腐殖质层厚度、坡向、林下植被盖度、凋落物层厚度是影响闽楠天然次生林自然更新的主要因素,偏相关系数在0.325 7 0.715 7之间,t检验结果为极显著或显著;模型复相关系数为0.966,F检验结果为极显著(F=30.96~(**))。[结论]闽楠下种母树株数对其幼树幼苗的更新起着最主要的作用,而郁闭度与株数密度过高或过低、凋落物层越厚、腐殖质层越薄、林下植被盖度越大均不利于其自然更新,同时,半阴坡、下坡位条件下的闽楠幼树幼苗的更新好于其它坡向与坡位。为促进闽楠幼树幼苗的自然更新,林分中闽楠下种母树应保留200株·hm~(-2)以上,以及对郁闭度、林下植被盖度及凋落物层厚度等实施相应的调控措施。     

Stock quality assessment through an integrated approach

Forest regeneration can be improved by matching seedling stock with reforestation site environmental conditions. To achieve this improvement, one must characterize seedling performance potential with anticipated field site conditions. A theoretical performance potential index (PPI) has been developed to forecast seedling field performance during the first growing season on a reforestation site. PPI includes material and performance attribute tests that characterize seedling performance potential under optimum and limiting environmental conditions. Test results are standardized and then integrated resulting in a comprehensive assessment procedure. The PPI concept is demonstrated using containerized western hemlock (Tsuga heterophylla (Raf.) Sarg.) seedlings subjected to a series of dormancy induction treatments and the results are compared with actual seedling performance during the first growing season on a reforestation site. Results indicated that PPI values for western hemlock seedlings treated with various dormancy induction treatments corresponded to field performance. Possible use of PPI in stock selection is discussed.     

Oak (<Emphasis Type="Italic">Quercus robur</Emphasis> L.) regeneration as a response to natural dynamics of stands in European hemiboreal zone

The oak (Quercus robur L.) regeneration intensity was assessed in the core area of the Białowieża National Park (BNP) in Poland with respect to the selected ecological factors. The emphasis was placed on the response of oak regeneration to disturbances, including the large-scale dieback of spruce stands. Defining their effect could help predicting the role of oak in naturally developing lowland forest ecosystems in the European hemiboreal zone. The results of the study challenge the opinion that the ‘lime-oak-hornbeam forest’ is a ‘climax’ community, confirming a very poor regeneration represented by only two saplings taller than 0.5 m per hectare. By contrast, in spruce-dominated communities, from 49 to 848 taller saplings per hectare were found. The occurrence of saplings was associated with discontinuous canopy of late seral stage of stands, as well as with large gaps. Most of the best quality grown-up oak saplings developed in the immediate neighbourhood of spruce logs. The results of the research indicate that ‘lime-oak-hornbeam forest’ (Tilio-Carpinetum) should be rather perceived as a transient community, evolved from relict, culturally modified, oak woodlands. Because spruce had become a dominating species only after abandoning in mid-1800s the historical regime of anthropogenic disturbances (involving frequent forest fires), the observed phenomena related to the disintegration of spruce stands had probably no precedent over the last 500 years. To confirm whether the massive decline of spruce stands will finally result in the successful establishment of the new canopy oak generation, both in Białowieża and other forests of hemiboreal zone, further research is needed.     

The effects of gap size and age on natural regeneration of Picea mongolica in the semi-arid region of Northern China

The aim of this work was to study the effects of gap size and age on natural regeneration of endangered tree species Picea mongolica W. D. Xu, which is only found in the semi-arid region of Northern China. For this purpose, six random transect belts of varying size were established in Baiyinaobao Natural Reserve. The number, height and age of P. mongolica saplings were inventoried. Results show that the total number of saplings per hectare and corresponding number and relative share of saplings in height class I (0.1–0.99 m) decreased along with increasing gap size, opposite to height class III (6–9 m). In height class II (1–5.99 m) the number of saplings per hectare and their relative share increased first slightly and then decreased with the increase of gap size. The number of saplings and their relative share in each height class changed similarly with the increase in the distance to the edge of the mature stand (p < 0.05). Gap age also significantly affect the number of saplings per hectare or their height distribution except in height class II. The distance to the mature stand edge played a very important role in the success of natural regeneration for species P. mongolica.     

Natural regeneration on planted clear‐cuts in boreal Sweden

Natural regeneration was registered on 97 clear‐felled and scarified sites in northeastern Sweden ten growing seasons after planting. On each site, three fix plots were laid out at planting and the planted seedlings were mapped. Ten years later all healthy non‐planted seedlings were registered in an anulus of size 15.7 m². Non‐planted seedlings were also observed in four 4 m² squares on each fix‐plot to estimate the zero‐square frequency. Species were classified as Pinus sylvestris, L., Picea abies (L) Karst. and deciduous species (Betula pendulajpubescens Roth./Ehrh., Populus tremula L., Alnus incana (L) Moench.). On average, 7 133 non‐planted seedlings ha^‐1 were found, of which 29% were conifers. Among the conifers, 71% were P. abies. More than 2 500 conifer non‐planted seedlings ha^‐1 were found on 27% of the plots. The number of non‐planted seedlings was correlated to the presence of neighbouring seed‐producing stands within 100 m and decreased with rising altitude. Pinus sylvestris seedlings were more frequent on dry soils while the deciduous seedlings were more frequent on wet sites. In the 4 m² squares, the zero‐square frequency was 29% if both conifers were and deciduous seedlings were considered and 63% if only conifers were considered. Mean height of the tallest seedling per species and square was 62 cm for P. sylvestris, 42 cm for P. abies and 107 cm for the deciduous seedlings. Key words: Alnus incana, Betula, broad‐leaves, deciduous, Norway spruce, Picea abies, Pinus sylvestris, Populus tremula, reforestation, Scots pine.     

Regeneration of tree species in the sub-tropical forest of Alaknanda Valley, Garhwal Himalaya, India

We studied the regeneration of tree species in the sub-tropical forest of Alaknanda Valley in Garhwal Himalaya, India. The overall regeneration status was fairly good in the study area. Seedling density ranged between 520 and 1,240 seedlings per ha while the density of saplings varied between 400 and 800 saplings per ha. Out of eight sites studied, five sites, viz., A1 , A2 , B1 , B2and C2contained the highest number of seedlings (280-480 per ha) and saplings (200-440 per ha) for Pinus roxburghii and remaining three sites viz., C1, D1and D2represented the highest number of seedlings (240-400 per ha) and saplings (200-240 per ha) for Anogeissus latifolius. The DBH class distribution of the tree species revealed that the highest number of individuals was concentrated in the lower diameter classes while smallest numbers were found in the higher diameter classes. Species such as Acacia catechu, Anogeissus latifolius, Dalbergia sissoo, Engelhardtia spicata, Lannea coromandelica, Mallotus philippensis and Pinus roxburghii have the largest number of saplings and seedlings in the lower DBH classes, suggesting that they have good regeneration potential. Other species such as Aegle marmelos, Bauhinia variegata, Bombax ceiba, Cassia fistula, Erythrina variegata, Haldinia cordifolia, Mangifera indica, Ougeinia oojeinensis, Phyllanthus emblica, Syzygium cumini, Terminalia alata and Toona hexandra have either no or very small number of saplings in the lower DBH classes, which indicates that the status of these species implies poor regeneration.     

Effects of pre- and post-planting shading on growth of container Norway spruce seedlings

Norway spruce (Picea abies (L.) Karst.) is shade-tolerant and sensitive to high irradiance, summer frosts and winter desiccation, which can impair its reforestation success. In this study, artificial pre- and post-planting shading was examined to determine their effects on post-planting shoot and root growth as well as the vigor of one- and two-year-old Norway spruce seedlings. Three planting experiments were carried out on open nursery fields (Exp. 1, 2) and on a mounded forest clearcut in central Finland (Exp. 3). Before planting, the seedlings were stored over winter either in a freezer or on open fields under snow cover. For two weeks prior to planting, half of the seedlings were placed in the open and the other half under a horizontal shade netting (light transmittance 56 %) (Exp. 1, 2). All seedlings were planted with or without a vertical post-planting shade, which was located on the southern side. Post-planting shading enhanced shoot growth and reduced damage (better visual vigor and needle color and less pine-weevil damage) on Norway spruce seedlings for at least two years after planting (Exp. 2, 3). Those seedlings, that had been stored over winter in the open and kept in shade prior to planting seemed to benefit most from post-planting shading (Exp. 2). However, post-planting shading may give variable results, depending on the seedling quality and weather conditions after planting, and may even reduce shoot growth if no pre-planting shading is used (Exp. 1). Shoot growth may also be improved at the expense of root growth (Exp. 3). The costs of manufacturing and installing post-planting shades may limit their use in practice, for example, to selected regeneration sites where there is high risk of frost damage but where no alternative silvicultural procedure (shelterwood or nurse crop) has been used.     

Naturally established seedlings on an artificially regenerated area in Northern Sweden

A field experiment in northern Sweden was established to compare different regeneration methods. Pinus sylvestris (L.) seeds of various origins were used. On the plots on the clear‐felled area where local seed had been sown, the naturally established conifer regeneration was recorded. Eleven growing seasons after sowing, the total number of seedlings increased by 335% giving a total of 4 754 seedlings ha^‐1 when the number of naturally established conifers was added to the number of seedlings from the artificial regeneration. The number of main crop plants almost doubled. The number of naturally established seedlings decreased with increasing distance from the neighboring seed‐tree stand. Up to 110 m from the seed‐tree stand 50% of the sowed 2 × 2 m quadrats had at least one naturally regenerated seedling. The extent of natural regeneration found in this study suggest that it could contribute to a significant increase in stand density under appropriate management on suitable sites. Moreover, naturally established seedlings on artificially regenerated sites may serve as an insurance factor in future perturbations, lead to better tree form shaping conditions and maintain genetic diversity even if material from a narrow genetic base is used for planting or sowing.     

Optimum planting density for Japanese oak (Quercus mongolica var.grosseserrata) based on spacing experiment with systematic design

A spacing experiment for Japanese oak (Quercus mongolica var.grosseserrata) with Nelder's design have been studied at the Kyushu University Forest in Hokkaido, since 1975. The oak seedlings were planted according to systematic spacings which were 20 levels varying gradually from 40,816 to 1,086 seedlings per hectare with concentric circular arcs (22 in number) and spokes (41 in number). In 1992 when the planted oak seedlings were 18-year-old, DBH, crown diameter, total height and clear length of the survival trees were measured. Based on the results obtained from analyzing the relationships between planting density and the mean values of each block, the optimum planting density should be 7,241 seedlings per hectare. The title is tentative translation from the original Japanese title by the authors of this paper.     

Influence of Stem Diameter on the Survival and Growth of Containerized Norway Spruce Seedlings Attacked by Pine Weevils (Hylobius spp.)

Pine weevils (Hylobius spp.) feeding on stem bark of young conifer seedlings pose a serious threat to forest regeneration-planting programmes in Nordic countries. This study was designed to determine the threshold diameter for planted, untreated containerized seedlings, above which pine weevils cause little or no damage. The effects of sublethal weevil damage on seedling growth were also assessed. In total, 5320 containerized spruce seedlings were planted on scarified and unscarified plots on three sites in southern Sweden. Seedlings in six size classes, which differed with regard to age (1.5-3.5 yrs) and cultivation density (28-446 seedlings m 2) were grown using the Combicell system. None of the seedlings was treated with insecticides, except for those in the smallest class, where both untreated and treated seedlings were used. Inspections were made periodically during the first 3 yrs and after both 5 and 7 yrs. A statistically significant relationship was found between seedling losses due to pine weevil attack and seedling stem-base diameter at the time of planting out, on both scarified and unscarified plots. For seedlings with a stem-base diameter of around 10 mm, mortality due to pine weevil attack on scarified plots was low enough to be considered negligible. This threshold diameter was several millimetres greater for seedlings planted on unscarified plots. An analysis of the relationship between the extent of weevil damage and seedling growth rate showed that among surviving seedlings, those that grew fast tended to show low levels of damage. On unscarified plots, the mortality rate amongst seedlings treated once with a permethrin insecticide was only one-third that of untreated seedlings. On scarified plots, the corresponding difference was somewhat smaller. Repeated insecticide treatment resulted in a pronounced reduction in seedling mortality on the unscarified plots, whereas the effect was weaker on scarified plots.     

Water relation patterns of bare-root and container jack pine and black spruce seedlings planted on boreal cut-over sites

Water relation patterns and subsequent growth were studied on bare-root and container jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana (Mill.) B.S.P.) seedlings during the first growing season on boreal cut-over sites.Containerized seedlings of both species had greater needle conductance compared to bare-root seedlings over a range of absolute humidity deficits. Needle conductance of containerized seedlings in both species remained high during periods of high absolute humidity deficits and increasing plant moisture stress. Bare-root seedlings of both species had a greater early season resistance to water-flow through the soil-plant-atmosphere continuum (SPAC) than container seedlings. Resistance to water flow through the SPAC decreased in bare-noot seedlings of both species as the growing season progressed, and was comparable to container seedlings 9 through 14 weeks after planting. Four weeks after field planting jack pine container seedlings had greater new root development compared to bare-root seedlings, while at the end of the summer both stock types had similar new root development. Black spruce bare-root seedlings had greater new root development compared with container seedlings throughout the growing season.     

金沙江干热河谷区退耕还林适宜造林树种筛选研究

金沙江干热河谷上段退耕还林区适宜造林树种筛选结果:甜酸角、山毛豆、苏门答腊金合欢、新银合欢、久树、印度黄檀等适宜在海拔1400m以下地带造林,构树、木豆、坡柳、余甘子、川楝等适宜在海拔1600m以下地带造林,山合欢、黑荆树、墨西哥柏、干香柏等适宜在海拔1400～1600m地带造林。木豆、坡柳、山毛豆等可进行直播造林,山合欢、黑荆树、川楝、苏门答腊金合欢、新银合欢、久树等采用百日容器苗造林,甜酸角、墨西哥柏、干香柏、印度黄檀等采用1年生容器大苗造林效果更好。块状整地(规格40cm×40cm×40cm),施有机肥加一定量的N、P肥作基肥,塘底施放高丙体粉防治白蚁危害,于雨季初期择时取苗造林,造林后应防止种植塘积水。造林苗木选用充分木质化的粗大壮苗;造林后和雨季中、后期及时清除种植塘周围杂草。     

山杏容器苗造林试验初报

采用田间试验方法,对葫芦岛地区山杏容器苗造林技术进行了系统试验与分析。试验结果表明,山杏容器苗造林成活率分别比裸根苗和直播造林提高14.7和33.4个百分点;山杏容器苗造林可在春、雨、秋三季进行,最佳造林时间分别为4月初6、月末、11月初;宜使用大、中型规格的容器杯培育苗木。     

Effect of slash removal on Gremmeniella abietina incidence on Pinus sylvestris after clear-cutting in northern Sweden

The Gremmeniella abietina outbreak in Sweden in 2001-2003 forced forest owners to sanitary clear-cut large areas of middle-aged Pinus sylvestris stands. There is, however, little knowledge of effective reforestation of P. sylvestris on G. abietina-infected sites. Gremmeniella abietina disease incidence on P. sylvestris seedlings planted in 2003 was studied with and without (control) removal of infected P. sylvestris slash. Removed slash was piled in stacks around the regeneration plots. The seedlings were planted within 1 year after sanitation felling on three sites in northern Sweden. One year after planting, G. abietina pycnidia were found on 32% of the control seedlings and total infection, including stem cankers, reached 44%. Total and G. abietina-induced mortality was 15 and 10%, respectively. The method of removing and piling the infected slash reduced the number of infected seedlings by 50% and seedling mortality by 27% 1 year after planting, compared with control. Consequently, even if there is a clear sanitation effect of removing infected slash to the sides of the regeneration area, it does not eradicate the infection source from the stands. Postponed planting, slash burning or complete removal of the infected slash is needed to minimize the infection risk. The positive correlation found between slash coverage and infection rate indicates that clear-cuts with large amounts of infected slash should be given priority for slash treatment.     

可降解容器苗生产装播线控制系统设计

工厂化容器育苗生产已成为我国发达地区苗木的主要生产方式。本课题研制出的气吸式精量播种控制系统可实现不同规格苗盘及不同形状种子的精确定量播种,通过HMI人机界面,用户可根据不同的苗盘类型及不同的播种次数进行参数修改,利用PLC控制实现容器苗生产的自动化。     

Influence of different forest conversion strategies on ground vegetation and tree regeneration in pine (<Emphasis Type="Italic">Pinus sylvestris</Emphasis> L.) stands: a case study in NE Germany

The conversion of anthropogenic into more natural, self-regenerating forests is one of the major objectives of forestry throughout Europe. In this study, we present investigations on permanent plots with different silvicultural treatment in NE German pine stands. Management of old-growth pine stands on acidic and nutrient-poor sandy sites differs in fencing, thinning, and planting of certain tree species. The investigations were carried out on the community, population, and individual level of the pine forest ecosystems. Thus, vegetation changes, size and height of tree populations, and height increment of tree individuals were observed over a time span of 6 years. Special attention was paid to short-lived tree species such as, e.g., Frangula alnus and Sorbus aucuparia, as well as to Fagus sylvatica as one of the most typical forest tree species of Central Europe. Vegetation changes are interpreted as a consequence of natural regeneration of formerly degraded forest sites, involving an increase in nutrient availability. High browsing pressure can be considered as a key factor for the inhibition of tree seedlings and growth of saplings. Some Sorbus aucuparia individuals, however, succeeded in growing out of the browsing height also in unfenced stands. Few found specimens of Fagus sylvatica proved that this species is able to establish spontaneously on these relatively dry, acidic sites under continental climate influence. Such natural regeneration processes, also including spontaneous rejuvenation of trees, can be integrated into silviculture as passive forest conversion management. An active management like thinning of stands, planting of trees, and fencing can accelerate forest conversion with regard to height growth and species number of trees.     

Site preparation of abandoned fields and early establishment of planted small-sized seedlings of silver birch

Field experiments at two sites in Sweden investigated the possibility of establishing silver birch (Betula pendula Roth) on abandoned fields by planting small (5–10 cm tall) seedlings. The effects of five modes of soil preparation (no preparation, rotary cultivation, deep ploughing, soil inversion, and removal of topsoil) with or without preliminary herbicide weed control on seedling performance were studied for three growing seasons following plantation. Both a split-plot design and a randomized block design were used to evaluate the experiments. Where there was no site preparation, seedling survival was close to nil. The highest seedling survival rates on the site with sandy soil were obtained on sites prepared by removing topsoil, or by transposing it by deep ploughing. On the site with silty soil, the best survival was observed on sites created by soil inversion or rotary cultivation. The tallest seedlings were found on sites with topsoil retained within the soil profile. Herbicide application with glyphosate promoted seedling survival and seedling height in combination with no soil preparation, but was of little effect when followed by mechanical soil preparation.     

Nursery fertilization enhances survival and physiological status in Canary Island pine (<Emphasis Type="Italic">Pinus canariensis</Emphasis>) seedlings planted in a semiarid environment

We tested the hypothesis that fertilized containerized Pinus canariensis seedlings increases survival when planted in semiarid sites through the improvement of their physiological status during the establishment phase by an increment in root growth. Seedlings were cultured under two different regimes: traditional (in non-fertilized natural soil) and alternative (in fertilized peat). Morphological attributes and nitrogen content were measured before planting. Measurements of survival and growth in the plantation were made periodically for 2 years and physiological plant responses (leaf water potential, gas exchange and chlorophyll fluorescence) during the third summer after planting were tested and finally a set of plants were excavated to measure the same parameters as before planting. Seedlings cultivated using fertilized peat achieved the highest values for all of evaluated parameters. During the third dry season, big seedlings exhibited better physiological status. Therefore, enhanced root growth can result in better water uptake during the dry period thereby increasing survival and growth in the next few years after planting. A feed-back physiological model is proposed to explain P. canariensis establishment in a semiarid environment.     

尾巨桉萌芽更新不同密度处理对林分初期生长的影响

对尾巨桉不同处理更新3.2a生林分的生长调查,分析结果表明:在密度1 110株/hm2时,植苗更新林分平均胸径比萌芽更新林分高6.8%;平均单株材积比萌芽更新高11.4%;萌芽更新林分平均胸径随保留密度的增大而减小,方差分析结果表明不同处理尾巨桉林分胸径生长有极显著差异。萌芽更新林分平均单株材积随保留密度的增大而减小,萌芽保留1 110株/hm2平均单株材积比2 100株/hm2减小26.5%。在相同密度1 110株/hm2时,植苗更新林分每公顷蓄积比萌芽更新高23.1%。萌芽更新林分单位面积蓄积随密度的增大而增大,林分密度2 100株/hm2的林分每公顷蓄积量比密度1 110株/hm2高53.7%。