Revealing the changes of labile nitrogen(LN)fractions in soil aggregates of eucalypt plantations at different ages is of great significance for better understanding of soil nitrogen cycles in such plantations.In this study,the state-owned Daguishan forest farm in Guangxi was selected as the research area,and the soil of eucalypt plantations with different ages(1,2,4 years)along with some adjacent abandoned land(control)during traditional rotation period were selected as the research objects.The undisturbed soil samples of the 0～20 cm soil layer were collected and divided into 4 granular aggregates by the wet sieving method,including＞2 mm,1～2 mm,0.25～1 mm and＜0.25 mm.The contents of LN fractions in soil aggregates of different sizes were determined.The LN components include Particulate Organic Nitrogen(PON),Microbial Biomass Nitrogen(MBN),Ammonium Nitrogen(Ammonium Nitrogen),Nitrate Nitrogen(NH4+-N),Nitrate Nitrogen(NO3--N)and Alkali-hydrolyzable Nitrogen(AN).The results showed that the content of LN in soil aggregates increased significantly as aggregate size decreased in the soil of eucalypt plantations of different ages,resulting in more soil LN distributed in＜0.25 mm aggregates.Overall,the content of LN in soil increased at first and then decreased after the planting of eucalypts,and the highest content was found when the plantation was 2-year-old,indicating that the soil nitrogen availability of eucalypt plantations was the highest at this age.Therefore,after eucalypt plantations reach age 2 years,attention should be paid to supplementing soil LN so as to maintain the nitrogen supply levels of eucalypt plantation soils.
In order to develop Eucalyptus cloeziana plantations,10 families of E.cloeziana were introduced from Australia to the southern Fujian mountains.The results showed that families 1212 and 1202 were the most excellent families,with average preservation rates of 85.56%at age 6 years.The average diameter at breast height(DBH),tree height,crown width,volume with bark and volume without bark were 15.42 cm,12.73 m,4.46 m,0.137 9 m3 and 0.116 4 m3,respectively.The genetic gains of above indicators were 8.56%,1.86%,4.83%,16.50%and 4.55%,respectively.The coefficient of variation of DBH,tree height,crown width,volume with bark and volume without bark ranged from 0.27%to 30.04%,belonging to the range of relatively small to moderate variation.The growth of trees within the family was relatively uniform,and the average wind damage index of selected families was 17.02%,lower than the population average of 14.98%.
The forest resources of Guangxi underwent great changes during the period from 2000 to 2021.The forest area increased from 9.819 million hm2 to 14.864 million hm2.The forest stock volume increased from 370.76 million m3 to 978.22 million m3.The forest covering rate increased from 41.32%to 62.55%.The forest land usage rate increased from 71.84%to 92.11%.The average annual growth rate increased from 4.09 m3·hm-2 to 7.97 m3·hm-2.The stock volume per hectare of forest land increased from 48.80 m3·hm-2 to 84.25 m3·hm-2.The annual growth of forests increased from 40.18 million m3 to 91.37 million m3,and the annual timber production increased from 16.37 million m3 to 38.99 million m3.Based on the results of continuous forest resource inventory in Guangxi from 2000 to 2021,the forest qualities were evaluated using the Analytic Hierarchy Process(AHP)that included 5 main aspects(forest origin,forest structure,forest productivity,forest health,forest value)and 37 sub-classification indicators.The results showed that the forest quality increased from passing grade to good grade from 2000 to 2021.The reasons for improving forest quality were systematically analyzed,and the important factors for improving forest quality were policy driven,market lead and increased investment along with strong,scientific and technological support which provided for scientific resource management.In order to further increase the forest resource quantity and promote forest quality in Guangxi,adjusting the structure of forest types,forest species structure,stand age group structure,tending of young stands,moderately reducing forest harvesting in the future were proposed.
Tissue culture technology is an important means for the regeneration and reproduction of woody plants.This paper summarizes the research progress of tissue culture technology and molecular regulation mechanism of organ re-generation in woody plants.This scrutiny of research progress has made it clear that establishment of regeneration sys-tems for woody plants is closely related to internal factors(explant genotypes,physiological states,etc.)and external factors(plant hormones,culture conditions,etc.).Gene expression,hormone signaling pathways and other signaling pathways play key regulatory roles in the process of de novo regeneration of woody plant organs.The difficulty in induc-ing adventitious buds and roots can be a bottleneck in the regeneration of woody plants.In the future,regulatory mecha-nism of regeneration of woody plants should be further studied to improve the regeneration efficiency and quality of woody plants.
To identify key NAC transcription factors involved in wood formation,a NAC transcription factor gene EugNAC007 of the clone DH32-29 of Eucalyptus urophylla×E.grandis was cloned based on RNA sequencing data and its function analyzed.The coding DNA sequence length of the EugNAC007 gene was found to be 1 711 bp and encodes an acidic protein with 569 amino acid residues of molecular weight of 64.32 KD.The EugNAC007 protein contained a typical NAC domain at the N terminus and shared relatively high homology with the Arabidopsis NAC with TRANSMEMBRANE MOTIF1(AtNTM1)that regulates cell division.The results of RT-qPCR showed that EugNAC007 was predominantly expressed in xylem tissues.Overexpression of EugNAC007 in poplar suppressed growth of tree height.These results indicated that the EugNAC007 may participate in the processes of wood formation through the regulation of cell division,but the regulation mechanism is still unclear.This study advanced deep excavation of NAC transcription factors involved in wood formation processes in Eucalyptus.
In order to cultivate fast-growing,high-yield,high-quality and efficient Eucalyptus urophylla×E.grandis coppice plantations,an experiment was conducted on the number of coppice sprouts per stump.From the data obtained,the growth and economic benefits of a 7-year-old E.urophylla×E.grandis coppice plantation were studied and analyzed.The results showed that the individual size of the stems was proportional to the volume of standing trees,and the maximum output value and profit rate could be obtained when the number of sprouts per stump was 2.It proved reasonable to select the effective number of stems per hectare at 1 755～2 025 for the cultivation of E.urophylla×E.grandis coppice plantations.The stand differentiation of retaining the above number of stems was not obvious,the yield was the highest and the economic benefit was maximized,which was suitable for promotion in afforestation practice.
In order to facilitate the swift and precise calculation of eucalypt forest volumes using relative tree height curve models for use in Guangxi eucalypt plantations,an optimal relative tree height curve model was developed using data gathered from 336 sample plots.The model was generated by fitting relative diameter(RDi)as the independent variable against relative tree height(RHi)as the dependent variable(RHi=(1-e-0.512 38)-0.826 11×(1-e-0.512 38×RDi)0.826 11).The model underwent validation,with the total relative error and average systematic error both falling below 2%,the mean percent standard error being less than 6%,and the estimation accuracy exceeding 99.7%.Through testing by tree species,region,and different forest stands based on average breast diameter and average tree height segments,the model displayed total relative errors and average systematic errors within 5%,with mean percent standard errors below 10%,and an estimation accuracy exceeding 98.0%.This suggests that the eucalypt relative tree height curve model developed is well-suited and versatile.It offers a rapid and precise method for estimating forest volume in the context of forest resource planning and design surveys,logging area design surveys,and forest resource asset assessments in Guangxi eucalypt forests.
Eucalypt has made great contributions to maintaining national timber security,promoting economic development and helping rural revitalization.The early use of eucalypt was mainly concentrated in the traditional industrial fields such as pulp and paper,fiberboard and plywood.The development potential was limited,the raw material consumption was large,the labor force was intensive,the product grade was low,and the processing level was shallow.Development of newer ways of eucalypt utilization is now urgently needed,along with developing new products to enable industrial upgrading.In recent years,through the joint efforts of eucalypt science and technology workers and production practitioners,new breakthroughs have been made in new ways of eucalypt utilization.These new ways mainly involve:(1)Cultivation of large-diameter timber to support increased solid wood utilization;(2)Production of viscose fiber to improve product value;(3)Cultivation of biomass energy forests for production of green energy;(4)Cultivation of ornamental eucalyptus for landscaping;(5)Extraction and processing eucalypt by-products to support development of new industries.This paper makes a comprehensive review of scientific research and industrial development progress in these five aspects with aim of providing a reference for promoting the transformation and upgrading of the eucalypt industry.
Monitoring and studying forest diseases and pests can better protect and manage forest resources,reduce the impact of diseases and pests on ecosystems,and improve the potential for sustainable forest development.Conventional forest pest and disease monitoring mainly uses image scale feature recognition to obtain monitoring results,neglecting the impact of vegetation moisture content on images which can result in significant errors in interpreting results.Therefore,this study of forest pest monitoring based on multi-spectral remote sensing images was proposed.The core spectra of forest multispectral remote sensing images were extracted step by step,the spectral response based on the multispectral remote sensing images was calculated.Next,the characteristic vectors of diseases and pests were obtained,the characteristics of forest diseases and pests were identified and the monitoring results of forest diseases and pests were generated by hierarchical classification according to the water content of forest vegetation.The results showed that the monitoring data obtained by the proposed method have a small error,with an average of only 0.010 125,indicating that the monitoring effect is good.By using this method,the degree of pests and disease incidence can be detected early and the trends of their spread monitored.Therefore,multispectral remote sensing images can help prevent further spread of pests and diseases,help to limit the damage to forests and meet the practical needs of forest protection.
A large amount of glyphosate herbicide is used in eucalypt afforestation.When the applied glyphosate exceeds the soil's degradation capacity,glyphosate cannot be quickly broken down and remains in the soil potentially affecting soil health and fertility.In order to investigate whether there is potential to reduce glyphosate use in eucalypt afforestation and to explore the short-term change rules of glyphosate residue in soils,this study examined a third generation Eucalyptus urophylla×E.grandis plantation as the research object.The standard local glyphosate concentration(3.375 kg a.i.·hm-2)was set as 100%base treatment,and then doses of 50%,75%and 125%of the base treatment were applied along with an artificial(manual)weeding treatment.Soil surface(0～20 cm)and subsurface(20～40 cm)soil samples were collected at 10,50 and 100 days after spraying the glyphosate to test herbicide impacts on the soil.The results showed that there was no significant difference in weeding effect between the 75%reduction treatment and the 100%local standard concentration treatment.Except for the 125%concentration treatment,the residual amount of glyphosate in surface and subsurface soil reached the international safety standard(＜0.1 mg·kg-1)by 100 days after application.The detection rate of AMPA(a decomposition product of glyphosate)increased with time up to 100 days.The ranks of glyphosate half-life were:high concentration treatment＞low concentration treatment,50～100 d＞10～50 d,and 0～20 cm＞20～40 cm.The results showed that the 75%reduction treatment can achieve expected effects,indicating that there is space for reduction of glyphosate application in eucalypt plantations whilst the use of additives could potentially further reduce the amounts of glyphosate applied.Overall,it was clear that glyphosate half-life in eucalypt plantation soil is positively correlated with the concentration of chemical applied and that it is shorter in surface than deeper soil layers.
Species of contaminated bacteria found in eucalypt tissue cultures were investigated by morphological and molecular biology methods in order to potentially reduce the incidence of deleterious contamination of such cultures.In total 50 species representing 25 genera of microorganism were identified from tissue culture bottles,including 7 species from 6 genera of bacteria along with 43 species from 19 genera of fungi,equating to 14.0%of contaminants being bacte-ria and 86.0%being fungi.Eucalypt subculture seedlings were mainly contaminated by Luteibacter yeoj uensis along with Penicillium spp.and Aspergillus spp.each with 5 species.Later after transplanting,it was found that eucalypt explants were contaminated by 21 species representing 11 genera of fungi and 1 species of bacteria.
Data from published literature on biomass measurements of Eucalyptus spp.(including E.urophylla×E.grandis,E.grandis×E.urophylla,E.urophylla×E.tereticornis and E.urophylla),Acacia spp.(including A.mangium,A.melanoxylon,A.auriculiformis,A.confusa and A.trinervata)and Pinus elliottii forests in different locations in China were collected and analyzed.The characteristics of three common estimation coefficients of biomass(biomass conversion and expansion factor BCEF,biomass expansion factor BEF,and root/shoot ratio R)in different forests and the relation-ship with stand structure characteristics(stand age,mean DBH,mean tree height,stand density,and standing volume),climatic factors(annual average temperature and annual average precipitation)and topographic factors(elevation)were summarized and differences examined.The results showed that the mean BCEF values of Eucalyptus spp.,Acacia spp.,and P.elliottii forests averaged 0.66 Mg·m-3,0.98 Mg·m-3 and 0.69 Mg·m-3,respectively,the mean BEF values were 1.26,1.61 and 1.66 respectively,and the mean R values were 0.19,0.23 and 0.22 respectively.The main factors influenc-ing the biomass estimation coefficients of Eucalyptus forests were tree height and stand density,while the biomass esti-mation coefficients of Acacia forests were mainly affected by DBH and stocking volume.Estimated biomass coefficients for P.elliottii forests were not significantly influenced by stand structural characteristics,but mainly by climatic factors(mean annual temperature,mean annual precipitation)and topographic factors(elevation).Therefore,differences in bio-mass estimation coefficients due to stand structure characteristics and climatic and topographic factors should be taken into account when estimating biomass of planted forests at the regional scale.
由丽赤壳属真菌引起的叶焦枯病是我国桉树人工林重要病害,选育抗病品种是防控该病害的重要途径之一.本研究将引起桉树叶焦枯病的3种丽赤壳属病原菌,通过孢子悬浮液(浓度为5 × 104 conidia·mL-1)喷雾接种法接种至14个桉树基因型苗木,通过比较感病指数来评估不同桉树基因型的抗病性.结果表明:不同丽赤壳属病原菌物种对同一桉树基因型的致病力存在差异,不同桉树基因型对丽赤壳属病原菌的抗病性差异达显著水平,其中桉树基因型GZ-1的抗病性最强.本研究结果拟为桉树人工林抗病基因型的选择提供一定的理论指导.
无人机遥感技术的不断革新为自然保护地的高效管理提供了技术支撑.本文研究和总结了2020-2022年以来利用无人遥感技术对湛江红树林自然保护区内红树林资源变化特征和外来物种入侵的动态变化情况.研究表明,湛江红树林国家级自然保护区内的红树林外来物种无瓣海桑和互花米草近三年的数据对比都有扩散的趋势,其中保护区内无瓣海桑增加167.9hm2,变化较大的区域集中在雷州半岛东海岸.互花米在保护区专项项目支持下进行了清理,2021较2020年面积下降,但2022年其面积较2020年增加了45.6％,在保护区全域扩散趋势明显.
通过测定7个粗皮桉无性系各个时期的胸径、树高、保存率和风害指标,分析其不同时期的生长差异,筛选和评价优良无性系.结果显示粗皮桉无性系间生长性状存在极显著差异.0～1.5年生时,粗皮桉无性系PL3的胸径增量最高,为8.18 cm;2.5～3.0年生时PL3胸径增量排名第二,低于对照无性系DH32-26;3年生时PL3的平均单株胸径、树高和材积分别为12.89 cm、16.51m和0.112 m3,高于对照DH32-29,PL3性状变异系数均低于DH32-29,说明无性系PL3生长具有优势,且个体间遗传差异比DH32-29小,稳定性好.PL3抗风性强于DH32-29、DH32-28,低于DH32-26.综合比较,粗皮桉无性系PL3的生长优势明显,抗风性强,可作为良种开发.
为了解桉树混交林研究现状和发展趋势,以CNKI数据库为文献来源,采用文献计量法对1978-2022年桉树混交林相关文献进行分析.结果表明:桉树混交林领域研究可分为缓慢起步、平稳增长和急剧上升3个阶段;前沿主题包括土壤养分、林分生长;研究趋势主要集中在桉树树种、伴生树种、生物量、混交造林等;农林类高校及科研院所、林场、林业局等单位是文献产出的主要机构,总体表现为省(自治区)内部合作较多、跨省(自治区)之间合作较少;作者主要来自科研机构或者高校,不同机构间交流和合作较少.
用材林是森林生态系统的重要组成部分,也是林业产业发展的重要物质基础.目前,国内外如何评价用材林林分质量没有统一的标准和方法.为推进林业产业高质量持续发展,有必要深入开展用材林质量评价研究.本研究以林分起源、林分结构、林分产能、林分健康、林分价值等5大类35项指标建立用材林质量评价指标体系,采用层次分析法确定各评价指标权重和评分标准,评价结果分为优秀、良好、中等、及格、不及格5个等级.以广西为例,按照上述评价方法对2015年广西用材林林分质量进行评价,结果为中等等级.
以尾叶桉和巨尾桉为对象,采用198株伐倒木样木数据分径阶形成建模数据,对比修正决定系数、总相对误差、平均系统误差、平均百分标准误差及预估精度指标,选定最优带(去)皮削度方程为d/D=[(H-h)/(H-1.3)](c0+c1Z0.25+c2Z0.5+c3(D/H));应用树高曲线(h=c1 ×(1-e-c3×D)c2)、树皮率方程(Pv=c1+c2× lnD)计算机理论造材,结合广西速丰桉木材市场计量实际需求,按2.6 m材长规格,分别编制尾叶桉和巨尾桉胸径树高二元经济材出材率表,精度达到了林业数表模型编制要求,可广泛适用于广西速丰桉伐区调查、森林资产评估等生产实践.
通过对近10年中国桉树人工林研究领域的相关文献分析,探讨其研究进展及发展趋势.检索中国知网(CNKI)数据库中2013-2022年桉树人工林研究的相关文献,利用CiteSpace6.1.R2软件对文献的年度发文量、作者、机构、关键词共现等数据进行可视化处理.结果表明:共检索获取3 938篇相关文献,其中年平均发文量为394篇,逐渐发文量总体基数相对较高,总体呈现相对下降趋势.作者与机构间的合作呈现出"高内聚、低耦合"的现象;具有较大影响力的作者分别为陈健波(69篇)、陈少雄(59篇)、郭东强(55篇);机构分布以广西大学(442篇)、中国林业科学研究院速生树木研究所(212篇)为主.研究热点为尾巨桉、病虫害、土壤养分、巨桉、桉树皮、挥发油、林业、森林资源、生态效益等;研究趋势为森林资源、林分生长、蓄积量、萌芽林、大花序桉、造林技术等.综合得出,近10年间中国对于桉树人工林研究的关注度整体较高,但机构间的交流与合作仍需加强;其研究热点与桉树木材利用和化工生产紧密相关,相关研究与发展的潜力巨大.
以波罗栎、滇青冈、高山栲、华山松、旱冬瓜、云南松等6个常见乡土树种为试材,通过对应用于采矿迹地植被修复造林初期成活率、保存率和生长量的追踪监测,探究乡土树种应用于采矿迹地植被修复中的可行性,结果表明:6种乡土树种应用于采矿迹地植被修复均能取得较高的成活率和保存率,但植被修复前期生长情况表现各异,其中旱冬瓜、云南松、高山栲在矿山迹地植被修复初期生长迅速,能快速成林,取得较好的植被恢复效果,可在今后的采矿区植被恢复中推广应用;华山松、滇青冈、波罗栎在采矿迹地植被修复中应用的可行性有待结合造林中、后期的表现进一步论证.
