飞播生产若干基本技术问题的研究与思考

对陕西飞播生产过程中若干基本技术问题进行了讨论,阐述了飞播的基本原理、飞播区、树种及种子、飞播作业、成效等内容。认为飞播属于人工促进的自然恢复方式,其实质就是通过种群演替实现群落演替。播区范围的确定应以地类的适播性为前提,选地适播。在群落学层次上,建群种或优势种是确定飞播树种的先决条件。对于种子质量,不仅仅只是播种质量,还需要注意种源质量。飞播作业的核心在于适时、准确落种。飞播成效上,飞播树种的成苗、成林效果是基本。同时,文中也论述了飞播生产中存在的技术偏差和误区,以及需要进一步研究和关注的技术问题。建议飞播在工程理念上应理性回归。     

Seed rain,soil seed bank,seed loss and regeneration of Castanopsis fargesii (Fagaceae) in a subtropical evergreen broad-leaved forest

Understanding the seed rain and seed loss dynamics in the natural condition has important significance for revealing the natural regeneration mechanisms. We conducted a 3-year field observation on seed rain, seed loss and natural regeneration of Castanopsis fargesii Franch., a dominant tree species in evergreen broad-leaved forests in Dujiangyan, southwestern China. The results showed that: (1) there were marked differences in (mature) seed production between mast (733,700 seeds in 2001) and regular (51,200 and 195,600 seeds in 2002 and 2003, respectively) years for C. fargesii. (2) Most seeds were dispersed in leaf litter, humus and 0–2 cm depth soil in seed bank. (3) Frequency distributions of both DBH and height indicated that C. fargesii had a relatively stable population. (4) Seed rain, seed ground density, seed loss, and leaf fall were highly dynamic and certain quantity of seeds were preserved on the ground for a prolonged time due to predator satiation in both the mast and regular years so that the continuous presence of seed bank and seedling recruitments in situ became possible. Both longer time observations and manipulative experiments should be carried out to better understand the roles of seed dispersal and regeneration process in the ecosystem performance.     

Genetic variation in seed and seedling traits of six <Emphasis Type="Italic">Haloxylon ammodendron</Emphasis> shrub provenances in desert areas of China

China is one of the countries most severely affected by desertification. Haloxylon ammodendron is an ecologically important component of the desert ecosystem and is one of the main shrub species used for ecological restoration. We compared the genetic variation in seed and seedling traits among six H. ammodendron provenances arrayed from east to west in China. The experiment was carried out in a greenhouse in well-prepared seedling beds (lines 1.5 m apart and seeds with in lines 1.0 m apart, 2.0 cm deep) with five lines (seven seeds per line) per provenance in a randomized block design with six replicates. The seed traits of fruit wing length, kernel weight, germination rate, and survival rate were compared, as were the seedling traits of internode length, branch number, assimilation shoot diameter, height, collar diameter, new shoot length, main root number, main root length, aboveground fresh weight, and underground fresh weight. Moreover, correlations between each seed and seedling trait and climate and geographical factors were assessed. The results show that the seeds from Dengkou County, Inner Mongolia had the best performance. Germination rate and survival rate were significantly positively correlated with longitude; and fruit wing length, kernel weight, seedling height, and new shoot length were significantly negatively correlated with latitude. Fruit wing length was significantly correlated with altitude. Among the climatic factors, the temperature in January had a strong direct effect on fruit wing length, germination rate, seedling height, and new shoot length. The mean annual rainfall had a strong direct effect on collar diameter. Humidity had a strong direct effect on survival rate. Seedling height, aboveground weight, and collar diameter could be important criteria for early provenance selection in the seedling stage. This study provides a reference for the selection of high-quality H. ammodendron seeds for drylands of northwest China.     

果翅、盐分及干旱胁迫对白梭梭种子萌发的影响

从生态学角度研究了果翅、温度、盐分和干旱胁迫等因素对白梭梭种子萌发的影响,结果表明:去除种翅能显著促进种子萌发,无翅种子比有翅种子萌发速率快(P<0.05),提早1 d达最高萌发率。变温条件有利于种子萌发。白梭梭种了萌发率随着NaCl浓度增加而降低,但在0.9 mol.L-1的浓度中仍有2%的种子萌发;将未萌发的种子移至蒸馏水中后,部分种子可以萌发,在较低浓度盐溶液(0.05～0.6 mol.L-1)中培养的种子其萌发恢复率低,而高浓度(0.7～1.0 mol.L-1)中培养的种子其萌发恢复率高。在较低程度的干旱胁迫下,白梭梭种子迅速萌发,而较高程度的干旱胁迫下种子萌发受抑制,在PEG浓度50%时不萌发;同等干旱胁迫程度下,无翅种子比有翅种子萌发率高。     

Seed dispersal and its implications for silviculture of African mahogany (Entandrophragma spp.) in undisturbed forest in the Central African Republic

The study of seed dispersal has received considerable attention in tropical ecology with emphasis placed on its role in the maintenance of species diversity. Since seeds of numerous high-value tropical timber trees are nominally or actively wind dispersed, the subject is also of interest to tropical foresters. In central Africa, up to 70% of harvested timber trees are wind dispersed, including African mahoganies of the genus Entandrophragma. The dual goals of managing many remote areas in central Africa for both biodiversity and timber production values has led to the consideration of low impact logging techniques. In the Central African Republic, increasing light downwind of Entandrophragma has been proposed as a way of increasing regeneration and recruitment of these trees. Mean wind direction at the time of dehiscence of Entandrophragma angolense and Entandrophragma cylindricum was compared with compass orientation of seed shadows for five individuals in mature, undisturbed forest. Mean wind direction was found to be toward the northeast for morning, afternoon, and daily winds and was significantly different from the orientation of seed shadows for all trees. Mean branch direction did not vary significantly from a random pattern, but matched the direction of the seed shadow better than wind direction did. It is concluded that harvesting interventions aimed at increasing light downwind of Entandrophragma will not necessarily benefit seedlings of the species at the study site and further silvicultural research is needed to determine appropriate management interventions, particularly in remote areas of Africa where conservation values are important.     

Seed Biology,Stand Characteristics,and Regeneration of Fraxinus rhynchophylla Hance

Fruit size and seed moisture content were measured and seed production and dispersal were monitored to understand the seed biology of the Korean ash (Fraxinus rhynchophylla Hance) in two Korean ash forests. A combination of four ground treatments and four crown closure levels were created in a natural forest to understand the site conditions needed for seedling emergence in natural stands and to determine practical regeneration methods for direct seeding. The seed size of Korean ash increased until late May and its moisture content decreased rapidly in early November. Prolific seed bearing occurred every 3 yr. The distance of seed dispersal by wind was about 30 m, but more than 90% of the seeds dispersed within 10 m from the seed trees. Twenty-five seed trees per hectare provided for successful natural regeneration. The seedling emergence in the natural stands was best with scarification treatment and 25～50% of crown closure.     

A Mechanistic Approach for Evaluating the Role of Wind Dispersal in Tree Population Dynamics

Abstract

We observed seed (or diaspore) dispersal of six species (4 species of Betulaceae, 2 species of Aceraceae) for 5 years in a species-rich deciduous broad-leaved forest (Ogawa Forest Reserve, central Japan), and explained the observed patterns with a mechanistic model of dispersal. The model involves three parameters which can be biologically interpreted; terminal seed velocity (F), tree height (H), and amount öf dispersed seed per reproductive individual (Q).The relationship between dispersed seed density and distance from a single seed source were explained well by the model. Two dimensional distribution of seed density dispersed from multiple seed sources was approximated by the model. We evaluated the dispersal success in reaching safe sites as the gap area covered by a given seed density, and discussed the adaptive meaning of the dispersal traits based on the model and empirical data. While Fdid not vary greatly among the species, Qshowed greater variation among the species in this forest. The species with large Qdescended more slowly (H/F)in this forest. The traits which were related to the enlargement of dispersal area tended to compensate for the low survival-of seedlings.     

凹叶厚朴种子保存方法及幼苗生长规律

对凹叶厚朴的种子保存方式及相应的播种苗的发芽情况、幼苗生长规律进行统计分析。结果表明:冷藏处理的凹叶厚朴种子发芽慢、发芽持续时间长;播种苗株高生长呈"S"型的慢—快—慢的规律,地径与叶幅生长表现出快—慢—快—慢的规律;株高、地径、叶幅三者之间的生长呈极显著正相关;种子经沙藏的凹叶厚朴发芽时间、出苗速度及发芽率均优于冷藏处理,而且,沙藏处理的苗高、地径、叶幅的累积生长量相应地大于冷藏处理。     

欧洲垂枝桦不同种源种子形态及萌发特性研究

以引进俄罗斯欧洲垂枝桦不同种源种子为材料,对不同种源种子形态及其萌发特性进行研究的结果表明:不同种源种子吸水量没有显著差异,而在种长、种宽、种厚、翅长、翅宽、千粒重、含水率、生活力、发芽率、发芽势和发芽指数存在显著差异;新西伯利亚种源种子最大、质量最重、发育最好、有生活力种子高达82.75%;采用混雪冷藏处理种子萌发能力最强,新西伯利亚种源种子发芽率、发芽势、发芽指数分别达到67.63%、55.41%、27.19;而对照种源采用低温冷藏处理种子萌发效果最差,其发芽率、发芽势、发芽指数分别为38.51%、32.42%、11.89。     

Reproductive strategies and seeds behavior of Betula platyphylla Suk. Population

Introduction6Birch(BetulaplatyphyllaSuk.)isaphotophilousandbroad-leaftreespecies,whichisdistributedwidelyinthenortheastofChina,especiallyinclearcuttingorburnedforestareasaftertheoriginalvegetationisdamaged(Zhou1986).Birchisjustapioneertreespeciesthroughsecondary-forestsuccession.Sincebirchpopulationoftengrowsrapidlyinalargearea,itusuallyhasagreatamountofseedstorage.Itstimberisanimportantrawmaterialinbuildingmaterials,suchasplywood,veneer,etc..Itsforesightisbroadlyprospectedonexplorationandap…     

Towards a DNA marker assisted seed source identification: a pilot study in European beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis> L.)

The widespread European forest tree Fagus sylvatica L. is of great importance for forest management. However, information about seed dispersal is still very rare, though important for harvesting strategies and later on seed source identification. We refined a DNA fingerprinting method for beech nut shells in order to directly assign dispersed seeds to their mother trees. A pilot study was conducted in two beech stands in Germany where leaves of the adult trees and the exocarp of dispersed seeds were fingerprinted at six nSSR loci. While one stand was randomly analysed for adults and dispersed seeds the other was systematically investigated following common harvesting procedures. Imitating the typical net harvesting strategy, seeds were collected beneath 19 adult trees. Exocarp genotyping revealed that on average three different mother trees contributed to a sample of five or six seeds collected beneath a single adult tree. Of the identified mother trees most were located within a radius of 15 m from the sampling point. The repeated pattern of seed dispersal within a short distance constitutes the basis for a straightforward strategy for the assignment of seed lots to a seed source stand. This strategy is based on the matching of individual genotypes without the necessity for a full inventory of the putative source stand. Additionally, we provide allelic ladders of five nSSR loci for standardization among laboratories.     

Development and evaluation of a real‐time PCR seed lot screening method for Fusarium circinatum,causal agent of pitch canker disease

Fusarium circinatum is a serious pathogen of Pinus spp. worldwide, causing pitch canker disease. F. circinatum can contaminate seeds both internally and externally and is readily disseminated via contaminated seed. Many countries require screening of pine seeds for F. circinatum before they can be imported. The currently accepted screening method is based on culturing the pathogen on a semi‐selective medium and identifying it using morphological traits. This method is time‐consuming and does not allow for accurate identification of the pathogen to the species level. A bulk DNA extraction and real‐time PCR procedure to screen seeds for the presence of F. circinatum were developed in this study. The real‐time PCR method resulted in the detection of F. circinatum in 5 of 6 commercial seed lots tested and has a lower detection limit of 1 × 10^?5 ng of F. circinatum DNA per PCR. The culture‐based method detected Fusarium spp. in four of six of the same seed lots. The real‐time PCR method can be used to screen multiple seed lots in 2 days, whereas the culture‐based method requires a minimum of 1–2 weeks. This new real‐time PCR seed screening method allows for fast, sensitive and accurate screening and can be adapted to handle larger volumes of seeds.     

不同催芽方法和播种期对福建山樱花种子发芽率与幼苗生长的影响

介绍了福建山樱花种子采集和处理方法,并研究了不同催芽方法和播种期对种子发芽率与幼苗生长的影响。结果表明,变温沙藏或冷藏的种子次年春播种的发芽率分别达94.5%和90.03%,变温沙藏的种子当年夏季播种的发芽率达83.8%,均能获得较高的发芽率;采种当年播种的苗木,以变温沙藏的地径和苗高为最大,分别达0.49 cm和24.47 cm,即采即播的地径和苗高为最小;采种次年播种的,以常温沙藏的地径和苗高最大,分别达0.90 cm和77.65 cm。     

Petroleum flotation technique upgrades the germinability of <Emphasis Type="Italic">Casuarina equisetifolia</Emphasis> seed lots

The germination of Casuarina equisetifolia Forst seed lots is low (40–50%) even when freshly collected. This study aimed at upgrading the germination performance by removing non-germinable seeds using petroleum flotation technique. Seeds collected from 19 individual trees in seedling seed orchards in India were assessed using X-ray to determine the proportion of different seed lot fractions. The feasibility of petroleum ether as a separation medium was tested. Morphological characters of floating and sunken seeds were further studied using image analysis technique to examine their effects on the separation efficiency. The X-ray analysis revealed a large quantity of shrivelled, empty and insect-damaged seeds, altogether accounting 50%, which were the causes of low percentage germination of un-graded seed lots (48%). Petroleum flotation resulted in 90% germination in the sunken fraction and 4% in the floating fraction. The separation was distinct for most seed lots, except few seed lots that had relatively low germination in the sunken fractions and more than 10% germination in the floating fractions. As a whole, petroleum flotation appears to be a feasible technique to upgrade the germination of C. equisetifolia seed lots, and its efficacy is influenced by wing surface area, seed density and wing quotient of filled and empty seeds.     

不同种子催芽方法对杜松育苗的影响

采用3种不同的方法对杜松种子进行催芽处理实验,结果表明:相比于混砂催芽方法和温、冷水交替浸种催芽法,采用热水浸种、变温催芽方法处理的种子,播种后出苗时间短,苗齐,其1年生幼苗高生长、地径以及壮苗数量都较高。在育苗上,热水浸种、变温催芽方法要好于其它两种方法。     

蒙古栎秋播种育苗技术的研究

自１９９３年起对本局大趟子苗圃进行了蒙古栎秋播育苗试验,并对蒙古栎从采种、种子调制、田间管理及起苗、留床、造林等环节上形成了一套完整的科学育苗方法,避免了春播育苗种子储藏和鼠害等一系列不利问题,研究探索了最佳播种量和最佳经营密度。     

云杉天然群体表型多样性研究

以系统揭示云杉全分布区天然群体表型变异程度和变异规律为目的 ,以其全分布区 10个有代表性天然群体 ,每个群体 30个个体为试材 ,对针叶、球果、种鳞、种翅和种子等 17个表型性状进行系统比较分析 ,采用方差分析、多重比较、相关分析和聚类分析等统计分析方法 ,讨论了群体间和群体内的表型多样性。结果表明 :云杉种内表型性状在群体间和群体内存在极其丰富的遗传差异。云杉球果、针叶、种鳞、种翅和种子 5个表型性状的变异系数分别为 19 14 %、2 6 4 6 %、13 5 8%、19 78%和 174 0 % ,种鳞性状稳定性较其他性状高。表型分化系数 (VST)的变幅为 2 0 9%～ 4 0 6 2 % ,群体间表型分化系数均值为 30 99%。群体间变异 (30 99% )小于群体内变异 (6 9 0 1% )。 17个表型性状间多数呈极显著或显著的正相关 ,球果长度、球果径、种鳞长度、种鳞宽度和种子千粒重为云杉易测定和重要的表型性状。云杉种内群体表型变异在空间分布上呈现以纬度为主的单向变异模式 ,利用群体间欧氏距离进行UPGMA聚类分析表明 ,云杉群体可以划分为 5类     

A rapid,automated flaw segmentation method using morphological reconstruction to grade wood flooring

Region-Growing Algorithms(RGAs) are used to grade the quality of manufactured wood flooring. Traditional RGAs are hampered by problems of long segmentation time and low inspection accuracy caused by neighborhood search. We used morphological reconstruction with the R component to construct a novel flaw segmentation method. We initially designed two template images for low and high thresholds, and these were used for seed optimization and inflation growth, respectively. Then the extraction of the flaw skeleton from the low threshold image was realized by applying the erosion termination rules. The seeds in the flaw skeleton were optimized by the pruning method. The geodesic inflection was applied by the high threshold template to realize rapid growth of the flaw area in the floor plate, and region filling and pruning operations were applied for margin optimization. Experiments were conducted on 512×512, 256×256 and 128×128 pixel sizes, respectively. The 256×256 pixel size proved superior in time-consumption at 0.06 s with accuracy of 100%. But with the region-growing method the same process took 0.22 s with accuracy of 70%. Compared with RGA, our proposed method can realize more accurate segmentation, and the speed and accuracy of segmentation can satisfy the requirements for on-line grading of wood flooring.     

Reproductive strategies and seeds behavior ofBetula platyphylla Suk. population

By the methods of morphological anatomy and investigation in the sample fields, the main studies were carried out such as morphological anatomy of reproductive organs, birch population’s reproductive ages, reproductive allotment value and seed behavior. The relationship between birch population and their surroundings was studied. The results showed that birch’s flower organs and its seeds were suitable well for spreading by wind. The seeds by wind can fly far away in a short time. The quantity of seed spreading greatly varied with different communities. Birch’s reproduction age can be changed in different ecological surroundings. The reproductive allotment value of birch was obviously different at different reproductive stages. In the mesic habitat, birch can grow well. The lowest reproductive age of them was 12, average age 15. In most cases the age of branches to bearing fruits was more than 18. The order of reproductive allotment values was as follows: a flowering phase > flower bud phase > fruit phase.     

Intra and inter-annual variation in seed rain in a secondary dry tropical forest excluded from chronic disturbance

Domestic livestock grazing and firewood extraction are chronic and pervasive disturbances in dry secondary forest that reduce diversity and modify composition. Exclosure of such disturbances may allow the reestablishment of original diversity. To investigate potential vegetation recovery following 30 years of perturbation, seed rain was evaluated monthly during 3 years in 96 0.78 m² seed traps located in eight exclosures established in 2006 in a species-poor secondary dry forest in central Mexico. Twelve additional seed traps were located outside the exclosures in 2010 for comparison purposes. Baseline diversity of seed sources (trees, ?5 cm DBH) was recorded to compare standing tree composition with seed rain. Also, baseline diversity of potential primary (birds) and secondary (ants) dispersal vectors were registered to infer current plant-animal interactions. Total seed rain over 3 years within the exclosures comprised 180,375 seeds from 61 woody species, an average of 1.12 seeds/m²/month. Half of these species (31) and 95% of the seeds falling within the exclosures belonged to trees typical of perturbed sites. Sixty percent of all recorded seeds belonged to an early-successional, bird-dispersed shrub (Hamelia patens Jacq., Rubiaceae). Seed rain at one non-excluded plot was dominated by the wind-dispersed early-successional tree Heliocarpus sp. (Tiliaceae). Richness and seed density increased significantly in the second year of exclusion; however, by the third year, richness remained constant while seed density decreased. Seed rain was richer and more abundant during the dry season and was dominated by wind-dispersed species. Phenology, successional status and the dispersal modes of woody species explained most variance in richness and seed density of seed rain in early-successional dry forest. Seeds of early-successional species were dispersed in equal measure by abiotic and biotic vectors, whereas biotic vectors dispersed a higher density of late-successional seeds. The amount and timing of fall of abiotically dispersed seeds of the three most abundant species in the standing tree community may prolong their current domination of the landscape. However, even when richness in the seed rain within exclosures remained constant through time, composition was gradually shifting towards animal-dispersed species which may start a positive feedback producing an increase in animal visitation and a further increase of richness.