Eco-physiological characteristics of Tetracentron sinense Oliv.saplings in response to different light intensities

The regeneration of Tetracentron sinense Oliv.is poor in the understory and in open areas due to the charac-teristics of natural regeneration of the species on forest edges and in gaps.It is unclear whether different light intensities in various habitats affect eco-physiological characteristics of saplings and their natural regeneration.In this study,the light intensity in T.sinense habitats was simulated by artificial shading(L1:100%NS(natural sunlight)in the open;L2:50%NS in a forest gap or edge;L3:10%NS in understory)to investigate differences in morphology,leaf structure,physiology,and photosynthesis of 2-year-old sap-lings,and to analyze the mechanism of light intensity on sapling establishment.Significant differences were observed in morphology(including leaf area,and specific leaf area)under different light intensities.Compared to L1 and L3,chloroplast structure in L2 was intact.With increasing time,superoxide dismutase(SOD)and catalase(CAT)activities in L2 became gradually higher than under the other light intensities,while malondialdehyde(MDA)content was opposite.Shading decreased osmoregulation substance contents of leaves but increased chlorophyll.The results suggest that light intensities significantly affect the eco-physiological characteristics of T.sinense saplings and they would respond most favorably at intermediate levels of light by optimizing eco-physiological characteristics.Therefore,50%natural sunlight should be created to promote saplings establishment and population recovery of T.sinense during in situ conservation,including sowing mature seeds in forest edges or gaps and providing appropriate shade protection for seedlings and saplings in the open.

Effect of nitrogen levels on photosynthetic parameters,morphological and chemical characters of saplings and trees in a temperate forest

Exploring the response differences of leaf physiology parameters to enhanced nitrogen deposition between saplings and trees is vital for predicting the variations of terrestrial ecosystem structure and function under future global climate change. In this study, the ecophysiological parameters of saplings and trees of Fraxinus mandshurica Rupr. were measured at different levels of nitrogen addition in a temperate forest. The results show that ecophysiological parameters maximum net photosynthetic rate(Pmax), apparent quantum efficiency(a), dark respiration(Rd), light saturation point(Lsp), photosynthetic nitrogen use efficiency(PNUE),specific leaf area(SLA)and stomatal conductance under saturated light intensity(Gsmax) were higher in saplings than in trees. These physiological parameters and not Nleaf(leaf nitrogen content)led to relatively lower Pmaxand Rdin trees. For both saplings and trees, low and median nitrogen addition(23 and 46 kg ha-1a-1) resulted in significant increases in Pmax, Rd, Lsp, Chl, PNUE, SLA and Gsmax. These parameters tended to decline under high additions of nitrogen(69 kg ha-1a-1),whereas Nleaf was always enhanced with increasing nitrogen. Variations in Pmax and Rd with increasing nitrogen were attributed to variations in the strongly related parameters of, Lsp, Chl, PNUE, SLA and Gsmax. Overall, the response sensitivity of physiological parameters to enhanced nitrogen levels was lower in trees compared with saplings.

Habitat associations of saplings and adults in an old-growth temperate forest in the Changbai mountains, northeastern China

Species-habitat association analysis is useful to detect spatial arrangement of individual plants, to discover rules about the distribution of species and to generate hypotheses about the possible underlying process controlling observed structures. Quantifying methods were used to classify habitats in terms of topographical variables in a mixed temperate broad-leaved Korean pine forest of the Changbai mountains in northeastern China. All of the 625 20 m × 20 m quadrats of the plot could be unambiguously assigned to one of three habitat categories （low-plateau, high-plateau and slope）. Torus-translation tests were used to estimate species-habitat associations. Many species are clearly distributed in a biased fashion with respect to habitats. Fifteen （55.6%） out of 27 species showed strong positive or negative association with specific habitats. We compared species-habitat associations at the sapling and adult stages. Adjusted density values indicated few species exhibit extremely strong habitat associations. Only 9 out of 26 species had adjusted densities 〉 3 in the habitat for which they had strong positive affinity. Few species show the same associations at the small tree and large tree stages. Only 3 out of 22 occurring associations with a specific habitat appeared to have a consistent habitat association at the two stages. These results suggest that species-habitat associations exist in the 25-ha plot of the temperate forest of the Chang- bai mountains. Owing to limitations in our statistical methodology, we partly underestimated associations by ignoring rare species. Regeneration niches can contribute to co-existence, but regeneration niches due to habitat associations play a limited role in species co-existence, since most species show a similar trend in habitat associations at the sapling and adult stages. We should pay more attention to shifts in habitat associations, i.e. niche shifts at different stages of existence.

Does nitrogen fertilization impact nonstructural carbohydrate storage in evergreen Podocarpus macrophyllus saplings?

Nonstructural carbon(NSC),which represents the relationship between the carbon source and carbon sink,is an important factor that reflects the functions and performance of a tree.However,little is known regarding the timeseries responses of NSC storage in evergreen species to different nitrogen(N)fertilization regimes.This study,which was based on a pot experiment,examined the response of the NSC(soluble sugars and starch storage to different N addition intensities[light N addition(LN):6.5 g N m^(-2)a^(-1);moderate N addition(MN):13.0 g N m^(-2)a^(-1);and heavy N addition(HN):26.0 g N m^(-2)a^(-1))]in saplings of the evergreen species Podocarpus macrophyllus.Our results showed that the net photosynthetic rate(P_(n))under MN was significantly higher than that under LN,but was comparable to that under HN.Moreover,saplings subject to MN had a significant higher leaf biomass than that to LN and HN.These results indicated that the C supply via photosynthesis under MN was greater than that under LN and HN.The NSCs reserve under MN was considerable with that under LN,which suggested that saplings in MN group consumed higher and stored lower properties of NSCs than those in LN group.However,saplings under HN stored higher properties of NSCs than those under MN considering that no difference in NSCs pools was found between the two treatments.The leaf N concentrations were found in the increasing sequence of LN<MN<HN,whilst the leaf chlorophyll concentration under HN was obviously lower than that under MN.The growth rate under MN was higher than that under LN and HN.We concluded that the NSCs allocation between con-sumption and reserve in P.macrophyllus saplings depended on soil N availability,and an excessive N addition to soil favors the storage rather than the consumption of NSCs by plants.

Effects of Different Water and Fertilizer Combinations on Tree Structure,Leaf Parameters and Photosynthesis of Apple Saplings

[ Objective] This study aimed to investigate the effects of different water and fertilizer combinations on apple saplings. [ Method] ＇ Tianhong 2＇ Fuji /SH40/Malus robusta Rehd. was used as the experimental material to analyze the effects of different irrigation modes and combinations of basal fertilizer and dressing fertilizer on tree structure, leaf parameters and photosynthesis of apple saplings. [ Result] The results showed that different water and fertilizer combinations ex- hibited varying effects on tree structure, leaf parameters and photosynthesis of apple saplings. To be specific, applying 432 000 kg/hm2 basal fertilizer, 480 kg/hm2 urea and 915 kg/hmz organic fertilizer ＋ 0 ＋ 915 kg/hm2 organic fertilizer as dressing fertilizer, and 1% urea as leaf fertilizer was conducive to promoting growth of branches and leaves, increasing leaf thickness, individual leaf area and SPAD, and improving photosynthesis of apple saplings under half root irrigation and whole root irrigation conditions. In addition, the effects were more significant under whole root irrigation conditions. [ Conclusion] Selecting the appropriate water and fertilizer combination is conducive to the growth of apple saplings.

Effect of Gamma Irradiation Doses on Morphological and Biochemical Attributes of Grape Saplings

The demand of grape in Bangladesh is fulfilled through import from foreign countries. The fruits of local cultivars of grapes are sour and seeded. Development of seedless grape varieties having increased sweetness, higher yield with better nutritional quality is necessary to reduce the import dependency. The present research activities are the part of a grape improvement project. A pot experiment was conducted at the Bangladesh Institute of Nuclear Agriculture (BINA), Mymensingh, during June to November 2011 to determine the suitable gamma irradiation doses on growth, leaf area and biochemical characters of grape saplings. Three vegetative bud stages viz. bud initiation stage, 4-leaf stage and 8-leaf stage, and four doses of gamma irradiation viz. 0, 5, 10, and 15 Gy were used as treatments. The experiment was laid out in a Randomized Complete Block Design with four replications. Different irradiation doses and vegetative bud stages showed significant variations in respect of plant growth characters, leaf area, soluble protein and total sugar content. Interaction effects also had significant variations on most of the parameters studied. Higher doses of gamma irradiation had showed detrimental effect on grape saplings. Generally, increased in irradiation doses showed decreased and detrimental effects on most of the parameters under study. Maximum numbers and length of roots, total dry matter, leaf area and chlorophyll-a and chlorophyll-b content were found at 5 Gy irradiation dose. Total soluble protein and sugar content of leaf were found maximum at no irradiation and 15 Gy, respectively. Higher number of roots and length, total dry matter, leaf area, chlorophyll-a, and b and soluble protein content of leaf were observed at bud initiation stage while 8-leaf stage showed maximum total sugar of leaf. In the combined effect of gamma irradiation and vegetative bud stages, all parameters showed best results in 5 Gy with bud initiation stage except total sugar content of leaf.

Growth Analysis of Nyssa yunnanensis Saplings

The growth of Nyssa yunnanensis saplings in Guanping area was monitored in 2011, 2013 and 2015. The results showed that the average basal diameter growth rate during 2013-2015 was higher than that during 2011-2013, and that during 2009-2011 was lowest; the average height growth rates in the durations of 2011-2013 and 2013-2015 were basically the same, and that during 2009-2011 was relatively slow; the growth of diameter at breast height（DBH） in the duration of 2013-2015 was significantly higher than that in the duration of 2011-2013. Comprehensive and better nature-returning work, as well as long-term and stable funding, is required for the protection of Nyssa yunnanensis.

Environmental and biological factors affecting the abundance of Prosopis flexuosa saplings in the central-west Monte of Argentina

Background:Trees and forests in drylands help mitigate the challenges through provision of economic products and vital environmental services such as habitat for biodiversity,prevention of erosion and desertification,regulation of water,microclimate,and soil fertility.The condition and changes in dry forests can be assessed by using ecological indicators able to quantify spatial and temporal changes in vegetation.One of the ways to determine the condition of the forest is to study the dominant tree species and its regeneration.Our study aimed to assess whether the abundance of Prosopis flexuosa saplings is affected by environmental and biological factors.Results:To evaluate the first variables we used data from remote sensing such as satellite images and Aster Global Digital Model(GDEM).The second set of variables was about exotic and native ungulates and we used feces of these animals and camera traps to take data.We found that sapling abundance related positively to sandy substrates and negatively to Wetness Index.On the other hand,in relation to biological variables,the abundance of saplings was positively affected by density of adult trees and by number of seeds dispersed by equines,but space use by Lama guanicoe had a negative relationship with saplings.This research shows that P.flexuosa saplings are benefited from sandy substrates and the conditions around adult trees.In addition to this,we found that exotic ungulates in low densities have neutral(i.e.cattle)or positive(i.e.equines)effects on sapling abundance.Conclusions:Based on these findings,we conclude that regeneration of the population of P.flexuosa in our study area has no major problems.In addition,we corroborated that the presence of exotic and domestic ungulates in low densities does not have deleterious consequences for saplings of the dominant tree,P.flexuosa.

林窗对黄檗幼树空间分布及生长发育的影响

【目的】林窗增加了林分空间结构的复杂性和林下生境的异质性,对林下幼树的更新具有重要影响。黄檗是我国国家重点保护野生植物,研究黄檗幼树的生长状况、空间分布与林窗空间结构的关系,有助于了解其对林下生境的适应性,对促进黄檗种群的更新具有重要意义。【方法】本文以2014年在北京百花山自然保护区内林下栽种的黄檗幼树为研究对象,于2021年对黄檗的生长及存活状况进行了调查,并使用背包式激光雷达获取了样地的林窗空间结构数据。采用空间点格局、生境关联性检验和方差分析等方法研究了林窗对黄檗幼树空间分布及生长状况的影响。【结果】(1)自然生长条件下,7年后黄檗幼树存活率为19.25%,在排除扩散限制后,存活黄檗幼树的空间分布表现为聚集分布。(2)林窗空间结构是黄檗幼树空间分布格局形成的重要原因,黄檗幼树分布与林窗边缘呈显著正关联,而与林冠区呈显著负关联。(3)黄檗幼树的基径在林窗边缘显著高于林冠区和林窗中心(P<0.01),在林冠区与林窗中心之间没有显著差异;黄檗幼树的冠幅和树高则呈现显著的梯度变化(P<0.05),即林窗边缘>林冠区>林窗中心。【结论】研究表明林窗对黄檗幼树的空间分布格局和生长状况具有重要的影响。林窗边缘的生境条件更有利于黄檗幼树的存活和生长,而林窗中心和林冠区则会对黄檗幼树的生长发育产生一定的抑制作用。

基于种子活力和苗期生长的枫桦半同胞家系初选

枫桦(Betula costata)为东北林区重要的用材和观赏树种,通过系统比较枫桦不同半同胞家系的种子活力和生长性状,为枫桦优良家系选择提供参考。以枫桦30个半同胞家系为材料,对家系间种子千粒质量、发芽率、发芽势、发芽指数、苗高和地径等6个性状进行方差分析和相关分析,并采用主成分分析法对参试家系进行综合评价。结果表明:种子千粒质量、发芽率、发芽势、发芽指数、苗高和地径在不同家系间差异均达到极显著水平;各性状的家系遗传力均高于0.88;不同性状间均呈极显著正相关;利用主成分分析法选择JL6、JL18、JL22、JL7、JL25和JL4为优良家系,优良家系的种子千粒质量、发芽率、发芽势、发芽指数、苗高和地径的平均值分别比总平均值高19.62%、15.97%、15.31%、26.81%、32.15%和14.49%,遗传增益分别为19.46%、22.67%、22.79%、24.07%、32.07%和14.44%,上述家系的母本可以初步确定为枫桦采种的首选母树。

银缕梅扦插育苗技术

本文结合基层林业生产实际,介绍了从大棚建立、基质配置、穗条采集、扦插、移苗到病虫害防治全过程的银缕梅扦插繁殖方法,以期为银缕梅的人工繁育提供参考。

香榧的无性繁殖育苗与栽培管理技术

香榧是一种经济价值高的树种,为我国特有的木本油料树种。本文根据多年来生产实践,从香榧的花芽生长、授粉特点等生长结果习性和气象、土壤、海拔等适生环境方面入手,介绍了香榧的嫁接、扦插等无性繁殖育苗方法,以及香榧的栽植、施肥、土壤管理、整形修剪、保花保果和病虫害防治等管理技术要点,以期为广大香榧种植者提供技术参考。

石菖蒲林下生态栽培技术

石菖蒲不仅具有较高的药用价值,还可制作室内盆景,与兰花、菊花、水仙并列为“花中四雅”,市场前景广阔。本文从林地选择、种苗繁育、苗株移栽、生长期管理、病虫害防治、采收加工及采收后管理等方面介绍了石菖蒲林下栽培技术要点,以期为石菖蒲林下栽培提供参考。

Height growth of Korean pine plantation sapling in Benxi, Liaoning Province, China

The height growth of Korean pine plantation was investigated for different ages of saplings in Benxi city of the eastern Liaoning, China. The sapling and seedling age were determined by branch annuals. Results show that the mean height of third- to eight-year Korean pines ranges from 13.31 cm to 111.73 cm and only 19.4% of the saplings reached the height above 130 cm. The height （Y） of eight-year-old Korean pine increases linearly with the increment of ground stem （x） （Y=3.1x＋35.15）. The relation between height and age can be described by an exponential equation. The second year after planting of the Korean pine is considered as the key period of Korean pine growth really adapting to the local environment; plantation management should be strengthened in this year. The Korean pine seedlings need two years to adapt to the local environment, thus early care and management should be taken in the second year.

Indexes of Tree Structure of Cylindrical Pear Orchards at the Sapling Stage

The reasonable tree and population structure parameters of various cylindrical pear orchards were studied.The results showed that for 3-year-old ‘Xinli No.7’,the tree height was 3.48 m,and the trunk height was 63 cm;there were 63 branches per plant,which was equivalent to 19 971 branches per 667 m^2;the leaf area index was 1.62.For the 3-year-old ‘Xueqing’,the tree height was 3.03 m,and the trunk height was 74 cm;the number of branches per plant was 57,which was equivalent to 18 069 branches per 667 m^2;the leaf area index was 1.73.The cylindrical trees of the two varieties had the following characteristics: the canopy structure was tight;the branches were equally distributed,and the number of medium branches and short branches accounted for more than 60% of the total number of branches of the whole plant.

施肥处理对相思树种幼林生长的影响

为了研究不同施肥处理对相思树种幼林生长的影响,对相思树种人工幼林进行不同施肥方式和施肥配方试验,观测其胸径、树高及材积生长量的变化。结果表明:基肥不同配方对相思树种幼林胸径、材积的影响差异显著,对树高的影响差异不显著;追肥不同配方对相思幼林生长量的影响差异不显著,但不同树种间幼林生长差异显著。影响相思树种幼林生长的因素主次排序为树种>基肥>追肥。正交设计9个处理间,相思树种幼林生长的树高、胸径、材积都存在显著差异(P<0.05),其中,处理A_(1)B_(2)C_(3)和A_(2)B_(3)C_(3)相思幼林树高最高,处理A_(3)B_(2)C_(2)相思幼林胸径和材积最大。结果为发展相思树种人工造林提供了技术支撑。

松树株数识别的YOLOv5轻量化算法研究

随着5G技术的发展,其高带宽、低时延和高密度接入特点,促使云计算模式向“云-管-端”模式改变,边缘计算作为终端关键技术对人工智能算法在算力有限的终端上的部署成为关键。以苗圃验收环节中松树株数识别的视频检索算法为例,提出一种适用于人工智能算法在终端部署的轻量级苗圃松树苗检测计数算法。算法通过在YOLOv5网络的基础上引入MobileNet v3特征提取机制来实现网络的轻量化,将压缩激励网络(Squeeze-and-Excitation Networks,SENet)中的轻量级注意模块集成作为bneck基本块,提高网络对于特征通道的敏感程度,增强网络的特征提取能力;在IoU(Intersection over Union,IoU)基础上进一步考虑目标框和预测框的向量角度,使用SIoU损失函数作为预测函数,重新定义相关损失函数,从而使苗圃树苗预测框更加接近真实框。研究结果表明,改进后的模型参数量明显减少,改进后的网络模型大小与对比试验中的方法相比,模型在准确率(Precision)降低3.26%、平均精确率均值(Mean Average Precision,mAP)降低1.03%的情况下,帧率(Frame Per Second,FPS)提升了21.48%,达到71.43帧/s,计算量较原YOLOv5s减少了148.44%。证明该算法具有高效性和轻量性,为边缘计算终端人工智能算法移植提供算法原型。

氮沉降对杉木幼树生物量及其分配的影响

为了探索氮沉降对中亚热带常绿针叶树种的影响,在福建三明森林生态系统国家野外科学观测研究站开展模拟大气氮沉降试验,以杉木幼树为研究对象,设置了对照(CK,0 kg·hm^(-2)·a^(-1))、低氮(LN,40 kg·hm^(-2)·a^(-1))和高氮(HN,80 kg·hm^(-2)·a^(-1))3种氮浓度处理,分析植物生物量及其分配对氮沉降的响应。结果表明:(1)在不同浓度氮沉降处理下,叶、皮、干、枝、地上部分和总生物量与CK均无显著差异(P>0.05),而根生物量则在HN处理后显著升高(P<0.05)。(2)在LN处理下,叶质量比、枝质量比、皮质量比和干质量比与CK均无显著差异(P>0.05);而根质量比、根叶比和根冠比则显著增大(P<0.05),地上部分质量比显著减小(P<0.05)。在HN处理下,叶质量比、枝质量比、皮质量比、干质量比、根质量比、根冠比和地上部分质量比与CK均无显著差异(P>0.05);而根叶比则显著增大(P<0.05)。(3)在不同氮沉降处理下,叶生物量与枝生物量,叶、枝和干生物量与地上生物量均呈现极显著正相关关系(P<0.01)。枝生物量与干生物量在CK和HN处理下呈现极显著正相关关系(P<0.01),在LN处理下呈现极显著负相关关系(P<0.01)。地上生物量与根生物量在CK处理下呈现极显著正相关关系(P<0.01),在LN和HN处理下呈现极显著负相关关系(P<0.01)。氮沉降总体上促进了杉木幼树的生长,增加了生物量的积累,同时通过把更多生物量分配给根系来维持杉木幼树的正常生长。

不同种植模式对海南榴莲幼树生长的影响

以海南榴莲幼树为对象,调查研究不同种植模式对‘金枕’‘猫山王’和‘黑刺’等不同品种榴莲生长的影响。结果表明,在无间/套种模式下,‘猫山王’榴莲株高增长量达0.54m,显著高于‘金枕’的0.39m,其余指标增长也比‘金枕’大,表现较优;在槟榔—榴莲套种模式下,‘金枕’和‘猫山王’各项指标增长量差异不显著,‘黑刺’榴莲除株高增长量达到0.72m,显著高于‘金枕’和‘猫山王’外,其余指标增长量均显著低于上述两个品种;在百香果—榴莲间种模式下,‘金枕’各项指标增长量显著高于‘猫山王’,同时,‘金枕’在主干粗度、一级分枝粗度方面分别达到17.92mm、4.27mm,也显著高于‘黑刺’的9.62mm、2.75mm。此外,在槟榔—榴莲套种模式下,3个榴莲品种在主干粗度、一级分枝粗度增长上表现较好的同时,一级分枝长度增长量均达到38.30cm以上,远大于其他两种种植模式。综合分析表明,‘金枕’和‘猫山王’在各项指标增长上整体表现较好,是较适宜的榴莲品种;槟榔—榴莲套种是较适宜的榴莲种植模式。研究旨在为榴莲规模化种植提供参考。

湖南栎类天然次生林林分空间结构对林下幼树物种多样性的影响

【目的】林分空间结构是影响幼树物种多样性的重要因子之一,研究林分空间结构对林下幼树物种多样性的影响规律,可为提高生态系统结构的稳定性和进行合理的森林经营管理提供理论依据。【方法】在湖南省宁乡县青羊湖林场、郴州市五盖山林场、平江县芦头林场、益阳市龙虎山林场以及桑植县八大公山自然保护区内设置并调查了49块20 m×30 m的栎类天然次生林典型样地。以混交度、树冠指数、开敞度和聚集指数来描述林分空间结构,以Margalef指数、Auclair&Goff指数和Pielou指数来描述幼树物种多样性,采用Pearson相关分析、多元线性逐步回归法和典型相关分析3种方法探索乔木层空间结构对林下幼树物种多样性的影响规律。【结果】1)Pearson相关分析结果表明混交度对丰富度指数Margalef影响极其显著(P<0.01);对于均匀度指数Pielou指标,聚集指数对其有显著影响(P<0.05),混交度和树冠指数对其影响极显著(P<0.01);对于多样性指数Auclair&Goff指标,树冠指数对其影响显著(P<0.05),混交度对其有极显著影响(P<0.01);2)多元线性逐步回归分析结果表明,影响3个物种多样性指数的主导因子均为混交度和树冠指数;3)由典型相关分析结果得到,第一组典型相关变量关系数为0.6471(P<0.01),说明林分空间结构与幼树物种多样性在整体相关程度极显著,典型载荷分析结果指出,混交度和树冠指数是幼树物种多样性的关键因素;4)由上述3种统计方法的分析结果可知,混交度和树冠指数是影响湖南栎类天然次生林幼树物种多样性的主要驱动因子。【结论】混交度和树冠指数是影响湖南栎类天然次生林幼树物种多样性关键林分空间结构因子,因此可以通过调控树种混交程度和冠层结构改变林分结构的混交度和树冠指数,从而促进其天然更新,达到保护和丰富其幼树物种多样性的目的。