共查询到19条相似文献，搜索用时 250 毫秒
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红松人工林和相邻次生林林下红松天然更新种群格局分析 总被引：2，自引：0，他引：2
为了探讨球果采摘后红松天然更新幼苗幼树的生长生存现状,了解红松天然更新种群的动态,以红松人工林及其相邻蒙古栎次生林两种林分为对象,对红松天然更新幼苗幼树的分布状态及其生长状况进行了调查分析。结果表明:(1)红松人工林与蒙古栎次生林林内红松天然更新种群年龄结构都不完整,蒙古栎次生林内红松天然更新种群年龄对应于球果采摘强度的不同时期出现了两个峰值,而红松人工林内只有前4年生幼苗;(2)两种林分中1~3a红松天然更新幼苗的株/簇与簇数均符合指数函数变化,即红松幼苗幼树多以单株存在,簇生幼苗的数量占比很少;(3)蒙古栎次生林林内的红松天然更新幼苗在苗高和地径生长都比红松人工林内的具有优势,两种林分中1a和2a更新幼苗的苗高差异不明显,但3a更新幼苗的苗高差异显著;次生林内1~3a红松天然更新幼苗的地径均极显著高于人工林林内的红松幼苗。结论:在当前的这种球果采摘条件下,红松人工林及其相邻蒙古栎次生林林内红松更新幼苗幼树分布受到了很大影响,种群年龄结构不合理,大多数幼苗幼树以单株存在。 相似文献
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以海南霸王岭陆均松(Dacrydium pierrei Hickel)天然林为对象,在有陆均松更新幼苗幼树的林分中共设置调查样地35块,样地面积400m~2,调查陆均松幼苗幼树胸径(地径)、树高,胸径5cm以上的全部立木的胸径、树高,林分郁闭度、灌木盖度、草本盖度、枯落物厚度、经纬度、海拔、坡度、坡向等因子。分析陆均松天然更新林分的组成、结构、分布及变化特征,结果表明:(1)陆均松天然更新林分的树种多样性丰富,Simpson指数均超过0.8;均匀度高,Pielou指数均大于0.4;随陆均松幼苗幼树高生长,丰富度指数、多样性指数和均匀度指数均呈逐渐增大的趋势。(2)林分优势树种组明显,断面积最多的5个树种是陆均松、岭南青冈、细刺锥、米椎和红绸,占总断面积的38.2%。(3)随着陆均松幼苗幼树的生长,乔木郁闭度和枯落物厚度呈增加趋势,林下植被盖度呈先增加后减少的趋势,林分断面积呈先减少后增加的趋势。(4)陆均松幼苗幼树主要集中分布在距陆均松母树10~30 m范围以内。(5)陆均松幼苗幼树在海拔1 140~1 180m、坡度为0~15°和西南坡向区域分布最多。 相似文献
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《林业科学》2021,57(3)
【目的】研究华北落叶松人工林天然更新的主要限制因素,探索寻找促进天然更新的实用技术,为改善华北落叶松林天然更新和林分结构提供技术支撑。【方法】在宁夏六盘山选择5个试验点,每个试验点按林冠郁闭度不同选择华北落叶松人工林5类生境(近熟林的林冠下、林隙、林中空地、林缘和退耕幼龄林地),每类生境各设1块12 m×20 m样地,2018年10月中旬在每块样地设置割草、除落、开沟、挖穴和对照5种处理,采用完全随机区组设计,每个区组平行于等高线排列,地表处理后撒播华北落叶松种子(100粒·m~(-2))。整个试验共设置25块样地,每块样地5种处理,每种处理3次重复。在近熟林林冠下和退耕幼龄林生境设置防止鸟鼠采食种子的尼龙网覆盖和不覆盖2种措施。2019年6月计数存活幼苗,并进行统计分析。【结果】不覆网时,退耕幼龄林、林缘、林隙、林冠下和林中空地5类生境的幼苗密度均值依次为2.7、1.8、1.4、1.3和0.8株·m~(-2);开沟、挖穴、清枯、割草和对照5种处理幼苗密度均值依次为2.1、1.9、1.8、1.3和1.1株·m~(-2);每类生境的5种处理之间,最高的平均幼苗密度依次为林缘样地开沟4.1株·m~(-2)、退耕幼龄林样地割草3.6株·m~(-2)、林隙样地开沟2.4株·m~(-2)、林冠下样地挖穴2.1株·m~(-2)、林中空地挖穴1.3株·m~(-2)。林地覆网能极显著提高所有处理的幼苗密度。近熟林内林冠下样地的幼苗密度均值提高幅度依次为清除枯落物2.3株·m~(-2)、开沟1.0株·m~(-2)、对照0.5株·m~(-2)、挖穴0.5株·m~(-2)、割草0.5株·m~(-2),即可提高0.5～2.3株·m~(-2);退耕幼林样地的幼苗密度均值提高幅度依次为清枯2.3株·m~(-2)、开沟1.7株·m~(-2)、挖穴1.3株·m~(-2)、割草0.6株·m~(-2)、对照0.3株·m~(-2),即可提高0.3～2.3株·m~(-2),与近熟林内林冠下样地基本一致。【结论】限制华北落叶松人工林天然更新的主要因素包括动物采食种子、过厚枯落物层阻碍幼苗根系进入土壤、病虫危害、杂草竞争和过密林冠遮荫等;建议采取的最佳复合措施为:通过间伐形成或选择业已存在的中等郁闭生境(如未郁闭幼龄林、林缘、林隙等),在林地部分区域全部清除枯落物或大面积开沟,下种后覆盖防止动物取食种子的尼龙网,这样可大幅提高林下幼苗密度。 相似文献
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《中南林业科技大学学报(自然科学版)》2017,(3)
为深入了解降香黄檀Dalbergia odorifera人工林天然更新的特点及其与环境因子的关系,应用典型样地法,研究广西西南部岩溶石山降香黄檀人工林的天然更新,分析降香黄檀实生幼苗幼树的结构特征、空间分布格局,以及影响其种群更新的环境因子。结果表明:在20个5 m×5 m的样方中共调查降香黄檀幼苗幼树94株,其平均密度1 880株/hm~2,空间分布以随机分布为主。幼苗幼树的个体主要集中在DBH≤3 cm和H≤4.0 m以内,且胸径随树高的增加而增长;其多度随径级的增加而减少,随高度级的增加先增加后减少,均呈现偏锋型曲线。用Canoco对可能影响降香黄檀幼苗幼树更新的9个环境因子进行主成分分析(PCA)表明,选取的环境因子共解释幼苗幼树分布信息的81.91%,影响降香黄檀幼苗幼树密度的主要因子依次为草本个体数、草本覆盖度、林窗面积、土壤含水率、土壤表层p H值、灌木覆盖度、岩石裸露率、土壤有机质含量、灌木个体数。其中,降香黄檀幼苗幼树密度与草本个体数及其覆盖度之间存在极显著正相关(P0.01);土壤表层pH值、灌木覆盖度、岩石裸露率与降香黄檀幼苗幼树密度呈负相关。 相似文献
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为了揭示群团状择伐孔大小对冀北山地华北落叶松人工林持水性能及草本生物量的影响,对华北落叶松林草本生物量和枯落物持水性能进行了研究.结果表明:同一群团状择伐孔内的草本层生物量要高于群团状择伐孔外的生物量,面积为0.049hm2的择伐孔内外草本层生物量最大;而择伐孔面积为0.025hm2的枯落物生物量、最大持水量和有效拦蓄量最大. 相似文献
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为了解苏木山华北落叶松人工林枯落物组成,选择林龄48 a生的苏木山华北落叶松人工林为研究对象,测量了不同林分密度林内枯落物。结果表明:(1)研究区枯落物储量为10.71～19.54 t·hm~(-2),其中半分解层储量为5.90～11.92 t·hm~(-2),未分解层储量为4.81～7.63 t·hm~(-2)。(2)各林分密度枯落物储量为1 800株·hm~(-2)900株·hm~(-2)500株·hm~(-2)1 100株·hm~(-2)。枯落物厚度为2.40～4.72 cm,其中半分解层厚度为0.67～1.80 cm,未分解层厚度为1.73～2.92 cm。(3)各林分密度枯落物含水率均表现为未分解层小于半分解层,枯落物含水率为林分密度500株·hm~(-2)1 800株·hm~(-2)900株·hm~(-2)1 100株·hm~(-2)。 相似文献
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为加深认识天山微生境在植物幼苗定植过程中的作用,以天山北坡中部天山云杉(Picea schrenkiana var.tianschanica)1年生天然更新幼苗为研究对象,基于对幼苗性状和微生境因子的调查,通过对幼苗性状和微生境因子相关性的排序分析,解析幼苗性状与微生境因子之间的关系,探讨微生境因子对幼苗性状的影响。结果表明：显著影响天山云杉1年生天然更新幼苗性状的微生境因子有枯落物层厚度、土壤紧实度、草本层高度、草本层盖度、苔藓层盖度、枯落物层盖度、海拔、根系盘结层厚度、土壤容重、土壤全磷和土壤含水量,这11个微生境因子可解释天山云杉1年生天然更新幼苗56.01%的性状变异,其中枯落物层厚度、苔藓层盖度、土壤紧实度和土壤容重占总解释率的55.13%。在天山云杉天然更新的定植过程中,微生境因子中地被物类型及土壤的疏松程度对1年生幼苗性状有较强的影响。 相似文献
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[Objective]To compare the differences of seed morphological characters among provinces of Quercus variabilis Bl.,and explore the adaptive growth status of seedlings growing in the central distribution area. [Method]The seeds of 6 Q. variabilis provenances from six provinceswerecollected, and the seedlings were cultivated and transplanted to experimental field in the centre of natural distribution range (Wuhan Jiufeng National Forest Park), then the seed morphology and one-year seedling growth traitswere surveyed. [Result](1)There were significantor extremely significantdifferences among provenances in seed length, seed width, seed length/width ratio and 100-seed mass, the order of seed length among provenances was Beijing Provenance (22.28 mm),Hubei Provenance (22.10 mm), He'nan Provenance (20.80 mm), Shaanxi Provenance (19.57 mm), Yunnan Provenance (18.93 mm)and Liaoning Provenance (18.81 mm), the seed width of Beijing Provenance (19.71 mm) and Hubei Provenance (19.16 mm) was higher than that of the others, the seed length/width ratio of He'nan Provenance (1.38) was extremely significantly higher than that of the others; (2)There were significant or extremely significant differences among provenances in seedling height, ground diameter, leaf number, branching number and seedling height/ground diameter, the Beijing Provenance and Hubei Provenance were better in seedling height and leaf number, which were respectively 19.54 cm and 20.26 cm, 8.32 leaves and 9.50 leaves; (3)A decreasing trend with time for seedling growth traits among provenances was found; (4)There was a positive relationship between seed morphological characters and seedling growth traits except seed length/width ratio; the leaf number was significantly related to ground diameter and branching number and the seedling height and leaf number were closely related to the seed morphological characters; (5)It showed a decreasing trend with the growth time in the relationship between seedling growth traits and 100-seed mass. [Conclusion]The seedlings of Beijing Provenance and Hubei Provenance grew better in the experimental field which might be related to their larger seed mass, and the Yunnan Provenance in the south margin and the Liaoning Provenance in the north margin of distribution area of Q. variabilis grew weaker than the provenances in the centre of distribution area.With the effect of climate change, provenances in the margin of distribution area may lose in the community competition in the seedling stage if it cannot take advantage of its dispersal and settlement and affected by the disadvantage of growth and competition, so that the distribution and population renewal would surely be affected. 相似文献
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Seedling emergence, growth, and allocation of Oriental bittersweet: effects of seed input, seed bank, and forest floor litter 总被引：3，自引：0，他引：3
Joshua W. Ellsworth Robin A. Harrington James H. Fownes 《Forest Ecology and Management》2004,190(2-3):255-264
The establishment of invasive plant populations is controlled by seed input, survival in the soil seed bank, and effects of soil surface disturbance on emergence, growth, and survival. We studied the invasive vine Celastrus orbiculatus Thunb. (Oriental bittersweet) to determine if seedlings in forest understory germinate from the seed bank or from seed rain. We also conducted a greenhouse experiment to investigate the role of leaf litter mass and physical texture on seedling survival, growth, and allocation. In the understory of an invaded mixed hardwood forest, we measured seed input, seedling emergence with seed rain, and seedling emergence without seed rain. Mean seed rain was 168 seeds m−2: mean seedling emergence was 107 m−2, and there was a strong correlation between seed rain and seedling emergence. The ratio of seedlings to seed input (0.61) was close to the seed viability (0.66) leaving very few seeds to enter the seed bank. Seed bank germination under field conditions was low (1 seedling m−2). Soil cores were incubated in a greenhouse to determine seed bank viability, and germination from these soil cores did not occur. To determine how litter affects seedling establishment and growth, we measured seedling emergence and biomass allocation in a greenhouse experiment. Seeds were placed below intact and fragmented deciduous leaf litter in amounts ranging from zero to the equivalent of 16 Mg ha−1. Seedling emergence was not affected by fragmented litter, but decreased to <20% as intact litter increased to 16 Mg ha−1. Increasing litter resulted in greater allocation to hypocotyl and less to cotyledon and radicle, and this effect was greater in intact litter. C. orbiculatus seedlings achieve emergence through forest floor litter through plasticity in allocation to hypocotyl growth. The low survival of C. orbiculatus in the seed bank suggests that eradication of seedling advance regeneration and adult plants prior to seed rain may be an effective control strategy. However, the intact forest floor litter of an undisturbed forest will not prevent seedling establishment. 相似文献
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《林业研究》2017,(5)
Emmenopterys henryi Oliv.(Rubiaceae) is an endangered tree species that is native to China.The wild populations of E.henryi have declined rapidly because of its poor natural regeneration,but the actual regeneration processes are not yet understood.In field tracking surveys and experiments in the Wuyishan Nature Reserve in Southeast China to determine the most important stage that affects the regeneration process,seed bank characteristics,seed germination,and seedling growth dynamics were studied in the typical habitats of E.henryi,Phyllostachys pubescens and broad-leaved forests.Results showed that in both P.pubescens and broad-leaved forests,more than 70% of the E.henryi seeds were distributed in moss and litter layers,and few were found in the soil beneath them.However,seed germination in the soil layer was significantly higher than in the moss and litter layers.Seed density,overall seed quality,and germination rate in the broad-leaved forest were significantly higher than in P.pubescens forest.Seed germination was highest in the microsites around the edge of the crown projection area of E.henryi mother trees.The order of survival rate of the seedlings on different ground surfaces was soil mosslitter.In both habitats,the average seed density was 24.9 seeds m~(-2),and the total germination rate was less than 3.5%.However,seedlings developed from only 1% of the germinated seeds,indicating that the seed germination is the most important stage in the natural regeneration of E.henryi. 相似文献
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J. J. Zhu Z. G. Liu H. X. Wang Q. L. Yan H. Y. Fang L. L. Hu L. Z. Yu 《New Forests》2008,36(3):247-260
Larix olgensis is one of the important commercial timber tree species in northeastern China, but it does not naturally regenerate in L. olgensis forests even after cutting. To identify the causes of the regeneration failure, the authors tested the effects of site preparation
in a thinned stand and in a clearcut on the emergence and early establishment of L. olgensis seedlings. The results indicated that there was no correlation between cumulative emergence percentage (CEP) of L. olgensis seedlings and canopy openness, but the CEP was significantly affected by site preparation (P < 0.001). The average seedling survival rates after treatments consisting of removing both litter cover and understory vegetation
cover were significantly higher in the clearcut than in the thinned stand (P < 0.001). Without site preparation, all seedlings in both the thinned stand and the clearcut disappeared within the first
growing season, meaning that ground cover (understory vegetation cover and litter cover) was not beneficial to seedling survival.
The average growth of seedlings exhibited significant differences between the thinned stand and the clearcut, and among the
site preparations (P < 0.001). Intensely thinned stands without ground cover improved seedling growth. These results imply that light and ground
cover might be the main factors limiting the early establishment of L. olgensis seedlings in managed plantation forests 相似文献
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草珊瑚林冠下播种育苗试验 总被引：2，自引：0，他引：2
草珊瑚播种育苗试验在杉木近熟林、阔叶树近熟林、毛竹林的林冠下进行,结果表明：不同树种林冠下的生长环境和土壤条件对草珊瑚种子的发芽率、苗木保存率及生长量均有显著影响;杉木近熟林林冠下较适宜草珊瑚的种子发芽率、苗木保存率、苗高、地径、主根长度、侧根长度、≥3 cm侧根条数7项指标平均达85.1%、83.6%、8.2 cm、0.18cm、5.3 cm、8.4 cm、4.2条。 相似文献
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A 10-year evaluation of the functional basis for regeneration habitat preference of trees in an African evergreen forest 总被引：2，自引：0，他引：2
Colin A. Chapman Kaoru Kitajima Amy E. Zanne Les S. Kaufman Michael J. Lawes 《Forest Ecology and Management》2008,255(11):3790-3796
The spatial distribution of tree juveniles in relation to light environments may reflect species differences in growth, survival, and functional traits and will shape the nature of forest regeneration. Long-term field experiments are important to evaluate this issue because of the potentially very long juvenile period in trees. Here, we combine a 10-year seedling survival–growth data with the results of community ordination and multivariate analyses of functional traits to ask how observed juvenile light guilds are related to species functional traits and seedling performance. We transplanted seedlings at a standardized height of 11 cm into the shaded understory and quantified their growth and survival for 10-years. Using the community-wide stem distribution data, we categorized 33 species including the focal 11 species to understory vs. gap/edge guilds. Then, we determined differences between the two guilds in seedling survival, growth, as well as seed size, adult height, and a series of leaf traits, including toughness and chemical traits (fiber, protein, phenolics, tannins, alkaloids, saponins). Among the 11 non-pioneer species whose seedlings were planted into the understory, there was no significant difference in 10-year survival between light guilds, but species in gap/edge guild tended to achieve greater height than species in the understory guild. The leaf chemical traits of 33 species did not differ between the two juvenile light guilds, but gap/edge species had smaller seeds, taller adults, and tougher leaves than understory species. We used logistic regression as a complementary approach to assess the extent to which plant traits varied between light guilds and the most parsimonious model based on AICc ranking included only leaf toughness and had an Akaike weight of 0.52. In addition, across the 11 species planted as seedlings, these traits were not significantly related to survivorship or growth over 10 years. A Principle Components Analysis illustrated associations among traits. We conclude that light guilds in terms of juvenile stem distribution could not be explained by long-term field performance of post-establishment seedlings alone. Earlier seedling stage or later sapling stage may be more important in differentiation of light guilds. For the species examined difference in growth rates could be linked to seed size and adult stature, but not to the adult leaf chemical traits considered. These results suggest the importance of examining ontogenetic shifts and relationships among functional traits for a better understanding of regeneration strategies of tropical trees. 相似文献
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《Forest Ecology and Management》2007,238(1-3):212-219
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. 相似文献
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利用ABT2号生根粉和NAA,研究不同叶面处理方式对长白落叶松移植苗生长量及质量的影响,结果表明:叶面处理方式不同,对长白落叶松移植苗生长的影响不同,其中,涂刷侧枝的处理方式对苗木生长量有促进作用,而喷洒处理方式则有抑制作用。涂刷侧枝时,ABT2号处理的苗高、地径平均为41.1 cm、0.46 cm,分别比对照提高了17%、5%;NAA处理的苗高、地径平均为37.4 cm、0.51 cm,分别比对照提高了7%、16%。喷洒时,ABT2号处理的苗高、地径平均为33.6 cm、0.41 cm,分别比对照降低了4%、7%;NAA处理的苗高、地径平均为31.4 cm、0.43 cm,分别比对照降低了11%、2%。 相似文献
19.
《Forest Ecology and Management》1997,98(2):149-165
The composition and density of seedlings, as well as height class distribution of woody species, were studied at two dry Afromontane forests in Ethiopia. A total of 40 species were recorded at Gara Ades and 41 at Menagesha forests. The density was 16 290 and 32 650 seedlings/ha at Gara Ades and Menagesha, respectively. A few species were not represented in the seedling bank, although mature trees were present. This may suggest that the species are under threat of local extinction or ‘that they recruit after major disturbances’. The trend in the height class distribution varied from species to species. However, about 50% of the species showed a negative exponential distribution at both sites, while there were indications of intermittent regeneration in the others. Seedling survival and growth of four species were also investigated, both under shade and in the open, at Gara Ades. The number of surviving seedlings declined progressively during the study period in all the species. Damage and uprooting by animals and people, drought, defoliation by insects and burial by siltation are among the apparent causes of seedling mortality. Mean annual height increment was generally low (< 15 cm) in the four species. Only one of the species showed more rapid height growth in gaps than under shade while the other three species had almost similar growth rates under shade and in gaps. The seedling growth analysis does not support the view that climax species quickly commence rapid height growth after canopy gap develops above them. The results show that in dry Afromontane forests, formation of seedling banks under the forest canopy is the major regeneration route of woody plants, especially climax species. 相似文献