A soil seed bank in a mature conifer plantation and establishment of seedlings after clear-cutting in southwest Japan

Compositions and spatial distribution patterns of buried viable seeds, and demographic transition from buried viable seeds to seedlings after clear-cutting were examined in a 75-year-old conifer plantation in southwest Japan. A part of the plantation was cleared in December 1997 and study plots were set up on a cleared site and a preserved site. Soil samples (a total of 105 l for the preserved plot and 90 l for the cleared plot) were collected from surface soils in spring 1998 and were incubated in a greenhouse for 120 days. There were an estimated 1064 buried viable seeds per square meter from 67 species in the preserved plot and 1754 seeds/m² from 53 species in the cleared plot. The soil seed bank was from mostly low density species with some high density species, and contained many pioneer species that were absent in the floor vegetation. Buried viable seeds were clumped together, especially in gravity-dispersal species. Although plenty of buried viable seeds were pooled in the soil, few seedlings emerged on the forest floor. In contrast, a number of seedlings, including many pioneer species, emerged in the cleared plots, showing a positive correlation between seed weight and germination rate. It is assumed that dominance of the seedlings established after clear-cutting depends on germination rates and/or growth rates of the seedlings rather than the initial density of buried viable seeds. These results suggest strong contribution of the soil seed bank to the establishment of the secondary vegetation after disturbance in a mature conifer plantation.     

化学药剂防治杉木种子园球果病害的室内药效试验

应用 10种化学药剂防治杉木种子园的 2种主要球果病害的室内药效试验结果表明 :内吸杀菌剂多菌灵、甲基硫菌灵对病原菌的菌丝生长、孢子萌发有强毒杀抑制作用     

Spatio-temporal variation of environmental signals inducing seed germination in temperate conifer plantations and natural hardwood forests in northern Japan

To document the spatial and temporal variation of environmental signals inducing seed germination in temperate forests, we measured temporal patterns of environmental signals and seed germination of six pioneer tree species in unthinned and thinned stands of conifer forests (Cryptomeria japonica plantations) and in the understory and gaps of hardwood forests in Japan. We also conducted germination experiment in laboratory for the six pioneer species to test the effects of red:far-red (R:FR) light ratio and temperature fluctuations on the seed germination. In conifer forests, the photosynthetic photon flux density (PPFD), the R:FR ratio, and the amplitude of temperature fluctuations in thinned stands were 2, 1.5, and 3 times higher, respectively, than those of unthinned stands. The PPFD and R:FR ratios just above forest floor also increased after the removal of thick litter accumulation. As a result, higher seed germination was observed in thinned compared to unthinned stands for three photoblastic species, whereas little differences were observed for three non-photoblastic species. These findings suggest that thinning, which frequently reduces litter accumulation, can substantially affect the regeneration of pioneer species and the resultant species diversity in conifer plantations. None of the measured environmental signals changed seasonally in unthinned stands of conifer forests, but they all changed remarkably in the understory of the hardwood forests. In this system, all signals were high and nearly identical to those in the gaps in early spring prior to canopy closure. Thus, the percent germination of the three photoblastic species was enhanced by high R:FR ratios and/or large temperature fluctuations even beneath the canopy and was nearly equal to that in the thinned conifer stands where the environmental conditions were nearly identical to those in the gaps. However, all of the environmental signals decreased with the expansion of canopy leaves and reached minimums at canopy closure. Even in the thinned stands and the gaps, the PPFD and magnitude of temperature fluctuations decreased over time due to shading by growing herbs and/or emerging canopy leaves. In these temporally changing environments, the germination of all photoblastic species ceased simultaneously. This study clearly demonstrated that the environmental signals inducing seed germination of photoblastic pioneer species spatially and temporally change in temperate forests, particularly in deciduous hardwood forests. Furthermore, these signals, PPFD, R:FR ratio, and the amplitude of temperature fluctuations, appear to play a very important role in tree regeneration and subsequent species diversity.     

Recovery of understory vegetation biomass and biodiversity in burned larch boreal forests in Northeastern China

Recovery of biomass and biodiversity of forest understory vegetation after fire disturbance has been widely studied; however, how this relationship changes and what are the determinants at different post-fire stages in larch boreal forests are still unclear. We investigated a chronosequence of 81 understory plots in larch boreal forests that were disturbed by fires in 1987 (S5), 1992 (S4), 1996 (S3), 2002 (S2), or 2007 (S1). Analysis of variance was conducted to test the differences of biodiversity and biomass among various post-fire stages. Different regression models were used to fit the relationship between biomass and biodiversity, while factors influencing this relationship were identified by boosted regression tree analysis. Results showed that total understory biomass increased from 2.51?t?ha^?1 in S1 to 8.47?t?ha^?1 in S3 and declined to 5?t?ha^?1 in S5. Similar dynamics were also found between species richness and species diversity. Positive linear correlations linked biomass and biodiversity throughout most of the post-fire periods. Slope and stand density were the two most important factors influencing the secondary succession of understory vegetation after fire. Geographical factors and overstory competition determine the orientation of vegetation recovery, and the impacts of climate on vegetation are muted after fire disturbances.     

Surface wildfire in conifer broad-leaved forests of the Hyrcanian region of Iran: short-term effect on regeneration and damage to trees

Wildfires in recent years have resulted in degradation and damage to the Hyrcanian forest ecosystems in Northern Iran.This study was carried out to investigate fire damage to trees and changes in regeneration in early-season growth after wildfires in the Golestan Province.For this purpose,a random sampling plan was used,with 60 circular plots(each plot is 1000 m2) for each stand and 240 circular(25 m2) plots for regeneration within the burned and unburned areas,respectively.In each plot,habitat factors were recorded,including crown canopy percentage,forest stratum,herb-layer cover percentage,species,diameter at breast height,tree and regeneration quality,and quantity of seedlings and saplings.Our results showed that bark is an important factor for fire resistance in Hyrcanian forests.The Persian ironwood and European yew has the highest and lowest fire resistance;as broad leave species are more resistant than needle leaf species.Density of regeneration in unburned area was higher than burned area,and statistical analysis showed significant differences for all species between two areas.Fire effects on sapling were different among species which indicates sapling has different resistance to fire.Forest floor fuel,season,stand composition and microclimate have more effects on fire severity while environmental factors,regeneration and management practices shaping future composition stands.     

赤松梢斑螟防治技术的研究

赤松梢斑螟(D ioryctria sylvestrellaRatzeburg)主要以幼虫危害红松幼林的球果、嫩梢和干部,造成红松种子产量下降、质量低劣,严重的可导致红松种子绝产。为了解决红松种子严重短缺的问题,利用2.5%溴氰菊酯、20%速灭杀丁、50%辛硫磷和40%氧化乐果等化学药剂,在黑龙江省苇河林业局林木种子园进行了赤松梢斑螟防治试验。试验结果表明,球果被害率可减少20%~85%,种子被害率减少25%~45%。     

The relationships between the number of seeds in the cones of Abies alba Mill. and their damage by spermatophagous insects

A study was conducted on the relationships between the total number of seeds in cones of Abies alba Mill. and the number of seeds that were viable, infertile, infested with the larvae of Megastigmus suspectus Borr. or damaged by Resseliella piceae Seitn. The seeds were obtained from cones collected in southern Poland in the Gorce National Park in both partial and strict reserves during 1996–1998. A total of 54,958 seeds extracted from 217 cones were used in the study. The data obtained were subjected to statistical analysis. Spearman rank correlation coefficient was computed. A correlation was found between the total number of seeds and each of the groups mentioned above except seeds infested with M. suspectus. An appropriate test was also used to compare the proportions of each of the groups. It was found that the proportions differ from year to year, and for the different sites, except the proportion of viable seeds. No correlation was found between the numbers of seeds infested with M. suspectus and the number of seeds damaged by R. piceae.     

青海云杉种实害虫发生危害研究

青海云杉种实害虫的主要种类为云杉球果小卷蛾,主要发生于天然林及母树木,虫害株率高达100%.-般低海拔林分重于高海拔林分,老母树林重于新母树林,纯林、疏林重于混交林和郁闭林分,远离天然林的种子园没有种实害虫的发生.在同一坡面上,随坡位升高虫害减轻,平缓林分重于陡坡林分,不同坡向间差异不明显;干燥林分重于湿润林分.平均单果虫口密度3头左右时,虫害果较健康果相比,出种率下降2.5%,健饱种数下降18.3%,虫蛀种子率达16.2%,千粒重下降0.93g,发芽率降低28%.     

Effects of single-tree selection harvesting on hymenopteran and saproxylic insect assemblages in the canopy and understory of northern temperate forests

Insects respond to changes in microhabitat caused by canopy disturbance, and thus can be used to examine the ecological impacts of harvesting. Single-tree selection harvesting is the most common silvicultural system used to emulate local small-scale natural disturbance and maintain uneven-aged forest structure in temperate forests. Here, we test for differences in richness, abundance, and composition of hymenopteran and saproxylic insect assemblages at four different taxon levels (selected insect orders; and all hymenopteran families, and braconid subfamilies and morphospecies) between the canopy and understory of unharvested and single-tree selection harvested sites in a northern temperate forest from central Canada. Harvesting had no effect on insect assemblage richness, composition or abundance at the three highest taxon levels (order, family and subfamily). Similarly, richness and abundance at the lowest-taxon level (braconid morphospecies) were similar, although composition differed slightly between unharvested and harvested stands. Insect assemblages were vertically stratified, with generally higher abundance (for Diptera, Hymenoptera, some hymenopteran families and braconid subfamilies) and richness (for braconid morphospecies) in the understory than the canopy. In particular, composition of the braconid morphospecies assemblage showed relatively low similarity between the understory and canopy. Single-tree selection harvesting appears to influ-ence wood-associated insect taxa only subtly through small changes in community composition at the lowest taxon level, and thus is recommended as a conservative approach for managing these northern temperate forests.     

西南地区麻疯树人工林有害生物种类及化学控灾技术

该文报道了西南地区麻疯树人工林中危害叶、花、果实和根的22种有害生物种类及其危害分布。麻疯树柄细蛾Stomphastis thraustica Meyrick、麻疯树蛀梢斑螟Oncocera faecella Zeller、蓖麻夜蛾Achaea janata Linnaeus、丽盾蝽Chrysocoris grandis Thunberg、长盾蝽Scutellera perplexa Westwood、绿鳞象甲Hypomeces squamosus Fabricius、堆蜡粉蚧Nipaecoccus vastator Maskell、黑翅土白蚁Odontotermes fomosanus Shiraki、烂皮病Phomasp.、白粉病Oidium monilioides Nees、灰霉病Botrytis cinerea Pers、麻疯树叶褐斑病Cercospora malloti Ell.、麻疯树枝枯病普遍发生,麻疯树柄细蛾、麻疯树蛀梢斑螟在1~3 a生人工林危害较重,灰霉病在苗圃危害较重,黑翅土白蚁、烂皮病在个别林分已引起少数树株死亡;麻疯树枝枯病在个别林分引起树株枯死率最高达85%,是麻疯树人工林最危险的有害生物种类。通过室内和林间试验初步提出了主要有害生物的化学控灾技术。     

我国种子库房的研究现状及发展趋势

种子产业现代化的发展很快,做好种子贮藏工作的一个关键因素是建立环境条件良好的贮藏种子的场所--种子库.本文介绍了国内种子库建设的现状及种子储藏环境,分析了我国种子库房的发展趋势.     

对半干旱地区草牧场防护林建设的探讨

草原(场),是发展畜牧业的必要条件,直接关系农业发展、农民增收、农村稳定.为实现对草场的可持续利用,龙江县加大草牧场防护林的建设力度,把“主副换位“、“牧业富民“进程作为新农村建设的重要内容,采取人工植树种草、改良和天然封禁的办法相结合,为草场建设绿色屏障,有效遏制了草场碱化、沙化、退化现象,为畜牧业的稳步健康发展创造必要的生态条件.     

张家口市园林树木害虫危害规律与防治对策

为全面了解张家口市区园林树木害虫的种类、分布及其危害规律,给防治提供理论依据,作者采用踏查和标准地调查的方法对张家口市区内主要街道、公园及城郊周边绿化的园林树木害虫进行了全面调查。结果表明,张家口园林树林害虫群落共有5个目20个科38种,优势种集中于天牛、蚧虫、卷叶蛾等类群及天幕毛虫、舞毒蛾等。并对不同类群的害虫提出了综合防治对策。     

应用菊酯油烟剂喷烟防治杉木种子园害虫试验

1993-1994年在洋口林场应用3Y－25型脉冲式烟雾机喷施0．05％溴氰菊酯油烟剂防治杉木种子园害虫的试验。结果表明：菊酯油烟剂喷烟可同时防治杉木球果麦蛾、杉木蝙长蝽及杉梢小卷蛾的成虫和幼虫。二次处理区球果虫害率比对照下降45．6％。     

Important insect pests of poplars in agroforestry and strategies for their management in northwestern India

Today, more than 143 species of insects infest both indigenous as well as exotic species of poplars in northwestern India, with about 65 species infesting Populus deltoides alone. Random sampling surveys (1984-2002) were undertaken in lower hills and plains of six states (Uttar Pradesh, Uttaranchal, Haryana, Punjab, Himachal Pradesh, and Jammu and Kashmir) in this region. The survey included 36 nurseries, 84 large ( ≥ 3 ha) and 255 small (< 3 ha) block and bund plantations and recorded seven species causing outbreaks. However, eight insects having wide spread distribution in this region were identified as posing a threat to agroforestry with P. deltoides and need to be managed. Amongst these, three species (Clostera cupreata, C. fulgurita and Apriona cinerea) were ranked as 'major pests' as they had relatively higher incidence (> 50% of attack) and caused extensive economic loss during outbreaks, coupled with tree mortality which persisted for several years in succession over large areas. Five insects were identified as 'potential pests', as they also caused heavy infestation and economic loss, but only in some years, on a localized scale and with no large scale plant mortality, but need to be checked to improve productivity. The 'potential pests' were: one species in plantations (Ascotis selenaria) and four insects in nurseries [(Eucosma glaciata , Phalantha phalantha, Nodostoma waterhousie and white grubs) with >50% incidence]. Integrated pest management practices, comprising cultural methods, use of bio-pesticides, tolerant poplar varieties/clones, natural enemies, recommended safe insecticides and avoiding alternate host plants of the pest, are discussed for important pests.     

Role of income diversification in protecting natural forests: evidence from rural households in forest margins of Sri Lanka

Ranchers need alternative livestock feeds when herbaceous forages become limiting in summer. Our objectives were to determine: (1) leaf and stem biomass components, (2) nutritive value [in vitro dry matter digestibility (IVDMD), total nonstructural carbohydrate (TNC), N, and N digestibility] of leaves for animal browse, (3) concentration of the secondary metabolites robinin and mimosine, and (4) in vitro leaf and bark toxicity for black locust (Robinia pseudoacacia L.) and mimosa (Albizia julibrissin Durz.), respectively, pollarded at 50 cm in Arkansas, USA. Black locust exceeded mimosa for every yield component (leaf mass tree⁻¹, leaves shoot⁻¹, shoots tree⁻¹, shoot mass tree⁻¹, stem basal area, and biomass tree⁻¹) except mass leaf⁻¹. Projected yields were 1,900 and 1,600 kg leaves ha⁻¹ for black locust and mimosa, respectively, assuming a population of 12,300 trees ha⁻¹. Mimosa leaves had greater IVDMD, TNC, and N digestibility than black locust. Mimosa leaves exceeded the nutritional N requirements of growing cattle (Bos taurus L.) and goats (Capra hircus L.), but protein supplementation would be needed for growing goats grazing black locust leaves. Tissue concentrations of secondary metabolites robinin and mimosine were below detectable limits in black locust and mimosa, respectively. The extract of black locust bark, but not leaves, was toxic to bioassayed African green monkey (Cercopithecus aethiops L.) cells. Either black locust or mimosa could provide moderate quantities of high quality, rotationally grazed forage for goats during summer months when herbaceous forage may in short supply.     

马尾松种子园无性系结实量、种实性状及遗传参数的分析

马尾松(Pinusmassoniana)是我国南方重要的用材树种。80年代初在马尾松主产区建立了一批初级无性系种子园,并开展了种子园有关营建技术的研究。反映种子园无性系繁育能力的种实性状包括了球果及种子性状,是林木种子园经营管理者所关注的重要内容,它涉及到种子园的产量和种子品质等问题。国外对火炬树(P .teada)、阿勒皮红松(P .abasica)、斑克松(P .banksiana)、白云杉(Piceaglaua)、北美黄杉(Pseudosugamenziesii)等树种(Matthewsetal.,1986 ;Matzirisetal.,1998;Todhunteretal.,1981;Horh ,1984 ;Clairetal .,1991) ,研究了花粉产量…     

意杨丰产林病虫害调查及其防治研究

意杨是睢宁县的重要用材树种.但目前病虫害日益增多.作者从1986年起,开展了主要病虫害的调查和防治试验.结果认为桑天牛、白杨透翅蛾、白杨舟蛾、杨树腐烂病是睢宁县意杨最重大的病虫害.文内还具体地论述了这些病虫害的危害症状、生物学特性、天敌及其防治方法.     

桉树病虫害的发生现状及防治策略

介绍了桉树病虫害的发生种类、严重程度，主要讨论了桉树病虫害发生的严重形势、发生原因及其防治对策。     

蚂蚁在舞草种子传播及避免其被啮齿类取食中的作用

选择云南思茅地区景谷县和西双版纳勐仑镇,研究蚂蚁传播舞草种子及避免啮齿类取食种子的影响,以探讨蚂蚁在舞草种群发生发展中的作用.结果显示:蚂蚁传播舞草种子的距离一般较近,但均超过种子自身的扩散距离.几种主要蚂蚁的传播曲线显示:传播的距离各自都有一高峰,平均传播距离为0.93～2.53 m.阻止蚂蚁搬运,景谷和勐仑实验点啮齿类对舞草种子的取食率分别为28.3% 和16.5%;而阻止啮齿类取食,蚂蚁搬运的舞草种子率白天可达77%,晚上为35.7%.成熟的舞草种子日释放时间与蚂蚁活动的时间吻合,蚂蚁可先于啮齿类将种子搬走.这表明舞草与蚂蚁互惠共生,使其种子既得以扩散,又减少了啮齿类的取食,从而促进种群的繁衍.