【作者】 张顺恒；

【导师】 陈辉；

【作者基本信息】 福建农林大学 ， 森林培育， 2010， 博士

【摘要】 桉树(Eucalyptus Spp)是世界三大速生丰产用材树种之一,20世纪80年代以来在我国华南、西南、福建东南部等地区广泛引种、大规模造林。本研究以福建省桉树主栽地区漳州、泉州、莆田、福州、宁德市为主要研究区域范围,以广泛推广种植的巨尾桉、尾巨桉、巨桉、尾叶桉等若干种桉树种(无性系)现实林分为主要研究对象,针对该地区桉树人工林培育中已经出现的或可能存在的养分利用率低、地力衰退、植被多样性受干扰等生态问题,从林地管理、林分结构调整、抚育及抚育间伐、土壤营养与养分补偿调控机制、混交造林等方面对桉树人工林生长、植被多样性、土壤肥力等的作用效应进行研究探讨,通过综合分析(经济效益分析、生态效益分析、持续利用分析等),提出构建桉树人工林生态培育优化模式和持续经营利用的关键配套技术,克服桉树丰产与地力消耗间的矛盾、改善生态环境、维护地力,为闽东南桉树人工林的可持续经营提供科学依据和技术保障,实现最佳的经济、生态和社会效益。主要研究结果如下：1、不同林地管理及林分结构调整(林地清理、整地、造林密度、抚育施肥、间伐等)的生态效应差异显著：(1)不同林地清理方式的研究结果表明,采用炼山方式清理林地后,林分生产力降低,3年生时树高、材积、蓄积均下降明显；炼山后林地受到人为干扰,严重影响林下植被的繁育和生长,造成物种多样性有所下降,土壤理化性状有所恶化,直接最终导致林地生产力下降。与炼山相比,不炼山林分平均树高、材积和蓄积量分别增加14.63%、22.16%和56.38%；林下植被种类和盖度分别比炼山的要多31.82%和9.57%；炼山后土壤密度增加4.92%、毛管持水量、田间持水量、毛管孔隙度、非毛管孔隙度、总孔隙度和通气度分别与不炼山的降低了9.02%、5.53%、4.52%、25.45%、9.62%和25.00%。土壤有机质、全N、全P、水解N、有效P、速效K分别降低了14.32%、27.45%、6.44%、33.55%、16.48%和27.83%。(2)不同整地规格、造林密度的研究结果表明,整地挖穴规格对人工林林分生长量及抗风性的效应不明显,而造林密度对林分生长量及抗风性均有显著或极显著的影响；整地规格对土壤肥力、林下植被以及水源涵养的影响较小,但造林密度对土壤肥力、林下植被以及水源涵养的影响却较大；综合林分生长量、抗风性、土壤肥力、林下植被多样性、水源涵养功能以及投资成本,在不严重影响生长量和抗风性的情况下,闽东南山地桉树人工林的整地方式,未必挖大穴,因为挖大穴不但增加造林成本,而且因动土面大、穴内土壤较松,一遇台风反而会加剧林分的风害程度(风倒木增加)。因此,闽东南沿海山地桉树造林整地挖穴规格以小规格(30 cm×20 cm×20 cm)即可。而造林密度以1110-1320株·hm-2较为适宜,不但有利于提高产量、增强抗风性且有利于地力维护。(3)经除草松土、垦覆、施肥等培育措施的桉树林分生长量明显高于无抚育施肥管理的林地,除草松土、垦覆、施肥等培育措施对桉树生长影响较大。经施肥管理,土壤肥力提高,可提供足够的养分给林木和林下植被生长,提高桉树林下植被多样性。适当的垦覆措施有利于提高土壤含水量和土壤空隙度,仅施肥管理有可能降低土壤的水分含量。适当的垦覆措施会使土壤容重变小,疏松多孔,提高土壤水分渗透速率和含水率,不会造成土壤紧实板结、土壤结构破坏或退化。土壤容重的降低使得土壤具有良好的孔隙结构,能够为植被根系提供较好的通气透水条件,可以促进林木生长。2、林地养分资源管理和土壤质量控制是生态培育中的关键技术措施。(1)桉树人工林养分生物循环研究表明,桉树人工林对N、K、Ca的需求量较大,对Mn、Fe有很强的富集能力。P的循环速率最低,仅为11.33-14.70%,其次为K元素(低于20%)；微量元素以Zn、Fe两元素为最低,仅在15%左右。因此,施用N、P、K、Ca肥是培育速生丰产林不可缺少的技术措施,对长期经营桉树的林地,在大量补充N、P、K、Ca肥的基础上,应配施适量的Mn、Zn、Fe肥以促进生态系统的养分循环,促进林木高产、稳产,维护地力。(2)对养分在林木各器官的积累分布及林分的养分生物循环速率研究表明,营养元素的积累量及分布比例,以叶为最大,其次为皮,叶、皮在生态系统中对养分平衡、地力维持有着重要的作用。林木吸收的养分中大部分存留在树体内,而仅有24.16-26.58%的养分由枯落物归还于林地。因此,在采伐利用时,如实行“全树利用”,那么约有73.42-75.84%的养分被输出；如只取走杆材,损失率则下降至15-20%,这有利于林分生态系统的养分循环。因此,在营林生产和采伐利用作业上,应尽可能多地保留采伐剩余物和枯枝落叶,在采伐时将叶、枝、皮归还林地及不炼山,有利于维持生态系统的养分再循环,防止地力衰退。3.桉树生长性状与立地各因子间的相关性研究,揭示了影响闽东南巨桉树人工林生长的主导因子是土层厚度厚、腐殖质层厚度、土壤有机质、坡位、土壤容重及有效磷含量。巨桉的树高生长随土壤有机质、土厚、腐殖质层厚度的增加而增高的趋势,而胸径生长则随坡位下降、土壤容重降低、有效P含量的增加而有增粗的趋势；随着海拔的升高,气温下降,通常对桉树生长影响较大,但巨桉耐寒性较强,试验地海拔在110-350 m之间,因而造成了海拔与生长量之间相关不大。但对其它耐寒性不强的桉树品系如尾巨桉等造林应该控制海拔高度,以避免冻害和出现可能产生的负面生态效应。4.通过抚育间伐合理控制巨尾桉林分密度,能获得较好的经济效益和生态效益。(1)从林下植被多样性、土壤理化性质和林分水源涵养功能的角度进行对比,长周期的巨尾桉人工林以间伐密度950株·hm-2的生态效应最好。巨尾桉林分物种丰富度、均匀度和多样性指数均表现出随密度增大而降低的变化趋势,说明保留合理的密度有利于林下植被的生长,促进桉树人工林生态系统的稳定。(2)从不同密度巨尾桉林土壤养分含量的测定结果,可以看出,随着保留密度的增大,2个土层厚度的土壤中各种养分含量均呈递增的趋势,在保留密度在950株·hm-2时林分的土壤养分达到最大,各项因子达到最佳。(3)土壤层是森林涵养水源的主体,土层厚度0-40 cm的土壤贮水量占土壤总持水量的90%以上,不同密度林分总持水量以950株·hm-2最大,为147.1t·hm-2，700株·hm-2最小,为133.3 t·hm-2,林分间伐密度偏大或偏小都会引起林分涵养水源功能降低,以间伐保留密度为950株·hm-2时,水源涵养功能最好。5、采用混交造林是桉树人工林生态培育有效的生物措施之一,研究结果表明：(1)混交林的生长量均有不同程度的提高,生长潜力大。采用杉木与桉树星状混交(8：2)不论对提高桉树还是杉木的产量以及地力维护都是有利的,适合作为15-20 a中长周期经营。而作为中短周期经营(8-12 a),采用桉树与卷荚等速生相思混交是个很好的选择。(2)混交林在维护地力上优势明显,对桉树人工林持续经营及防治地力衰退意义重大。桉树与杉木或卷荚相思混交,混交林内枯枝落叶量多、成分复杂且养分含量高,明显地改善了土壤理化性状,提高土壤肥力。此外,桉树与杉木或相思混交,由于形成特殊的复层林分结构,也促进了林下植被的发育,提高物种多样性。(3)根据试验研究和生产实践,由于两个混交树种成熟年龄不一,杉木与桉树混交,以培育大径材为目标,可实行中长轮伐期经营(15-20 a左右),但应注意种植密度不宜太大,并应采取翻耕、施肥等措施。巨尾桉-卷荚相思混交由于相思的生长速度会比桉树慢,短期内混交林的产量有可能不如桉树纯林,因此主伐时间应适当延长至8-12 a,不仅能提高林分产量,而且促进地力的改良,产生巨大的经济、生态和社会效益。更多还原

【Abstract】 Eucalyptus (Eucalyptus Spp) is one of the world’s three fast growing timber species widely introduced and used to afforestation since the 20th century 80’s in south, southwest, southeast of Fujian province. The research range of this paper is the main cultivated areas of eucalyptus in Zhangzhou, Fujian, Quanzhou, Putian and Fuzhou, Ningde and the research objective are eucalyptus clone species forest such as Eucalyptus granddis×E. uophylla,Eucalyptus urophylla×E. grandis, Eucalyptus grandis and Eucalyptus urophylla. The problems of the Eucalyptus plantation in these areas are low nutrient use, soil degradation, vegetation diversity reducing and other ecological issues. By researching the forest management, forest structure adjustments, tending and thinning, soil nutrients and nutrient compensation control mechanism, such as mixed planting of Eucalyptus plantations in terms of growth, vegetation diversity, soil fertility and analyzing the efficiency of economics, ecology and sustainability, this research constructed the ecological cultivation optimization model of eucalyptus plantation in Fujian Province and put forward the key technology of sustainable management, aiming at overcoming the contradiction between fast growing and soil fertility consumption, improving ecological environment, maintaining soil fertility. The purpose of the study was supplying scientific basis and technical support for sustainable management of eucalyptus plantations in southeast Fujian and achieving the best economic, ecological and social benefits. The main study results are as follows:1. There was significant ecological effects difference between different way of forest management and forest structure adjustment, such as forest clearing, soil preparation, planting density, tending fertilization, thinning and so on.(1) The different woodland clearance way showed that the forest productivity decreased after burning. The tree height, volume, accumulation decreased significantly of three years old forest. The forests were disturbed by human after burning. The growing of understory vegetation was effected, leading to the reduction of species diversity, deterioration of soil property and eventually leading to forest productivity decline. Compared with the burning, the average height, volume, stock volume, vegetation types,coverage, soil density in no burning forest increased by 14.63%,22.16%,56.38%,22.16%,56.38% and 4.92%. Capillary water, field capacity, capillary porosity, non-capillary porosity, total porosity and aeration decreased 9.02%、5.53%、4.52%、25.45%、9.62% and 25.00% respectively. Soil organic matter, total N, total P, hydrolysis of N, the effective P, available K decreased by 14.32%,27.45%,6.44%,33.55%,16.48% and 27.83% respectively.(2) Results showed that the interaction of soil preparation size and plantation density had no significant effect on forest growth and wind resistance. The plantation density had significant effect on forest growth and wind resistance. Compared with soil preparation size, plantation density had more significant effect on oil fertility, understory vegetation and water conservation. Taking all factors into consideration, such as forest growth, wind resistance, soil fertility, understory vegetation diversity, water conservation and investment cost, eucalyptus plantation in Fujian mountain area may not dig large hole which will increase invest cost and decrease wind resistance. So the size of soil preparation could mainly on small specifications, i.e.30 cm×20 cm×20 cm. And plantation density of 1110-1320 plants per hectare was suitable, which will help to improve output, improve wind resistance and maintain land capability.(3) Growth of eucalyptus forest after weeding, cultivation and fertilizing was significantly higher than those without tending. Weeding and fertilizing had significant effect on growth of eucalyptus forest. After fertilizing, soil fertility could be improved and provide sufficient nutrients to understory vegetation. The weeding, covered, fertilization and other measures to foster the growth of eucalyptus forest was significantly higher than those without the application of plots fertilization management, forest cover reclamation, fertilization and other measures to foster a greater impact on the growth of Eucalyptus. The manure management, soil fertility improvement can provide sufficient nutrients to understory vegetation, improving their diversity. Proper cultivation could help increase soil water content and porosity, with the result of soil volume weight reduction. Furthermore, the soil is more aerated and permeable, improving forest growth.2. The key technology measures for the eco-training were forest resource management and soil nutrient quality control (1) Study of nutritional characteristics of Eucalyptus and nutrient cycling showed that N、K and Ca were in hare demand and accumulation ability of Mn and Fe was strong. The cycling rate of P was the lowest, about from 11.33 to 14.70 percent, next to K. Microelement of Mn and Fe had the lowest cycling rate, about 15 percent. So, application of N, P, K, Ca was indispensable technical measures for long-term management of eucalypt woodland. Combining application of Mn、Z、Fe could promote ecosystem nutrient cycling, and stable yield of forest.(2) Study of nutrient accumulation and forest nutrient cycling rate showed that the distribution proportion of nutrition elements was leaf and bark in sequence. Leaves and barks played an important role for nutrition balance and maintenance of site fertility. Most of nutrient absorbing were in the tree body and only few of them return to forest site by litter, the ratio of which is about from 24.16% to 26.58%. When cutting and using, the best method was "whole tree application", which was good for the forest ecosystem nutrient cycling.3. Better economic and ecological benefits could be achieved by thinning and controlling reasonable stand density.(1) The density of 1200 plants per hectare for long period plantation forest could achieve best ecological benefits, demonstrating in vegetation diversity, soil property, water conservation. The species richness, evenness and diversity indices of Eucalyptus grandis were decreasing with the density increasing. So rational density is suitable for the growth of Eucalyptus and could promote the stability of eco-system.(2) Soil nutrient content was increasing with the density increasing, reaching the peak at the density of 1200 plants per hectare. Soil nutrient content was declining at the density of 1415 plants per hectare.(3) The results showed that the total water capacity of Eucalyptus forest aboveground was from 9.32 to 14.17 ton per hectare, with the most ratio of canopy class and the least ratio of litter. Total water capacity was increasing with the density increasing, reaching the highest value at the density of 1200 plants per hectare and lowest at the density of 600 plants per hectare.4. Mixed forest was one of the most effective bio-ecological cultivation measures.(1) Mass growth of mixed forest was higher than single forest. The fir- eucalyptus mixed with star shape at the ratio of 8 to 2 is advantageous for both the mass of fir and eucalyptus and the maintenance soil fertility, suitable for medium or long term management. The eucalyptus-acacia is suitable for medium or short term management. Results showed that eucalyptus- acacia mixed with star shape and the ratio of acacia between 30% and 50% is suitable for growth of eucalyptus and acacia. If mixed in line, the ratio of 2 line eucalyptus to 3 line acacia is suitable.(2) Mixed forest has obvious advantage of maintenance soil fertility. The eucalyptus- acacia mixed forest with more litter, more complex composition and higher nutrient content, coupled with the interaction of the roots, the soil property and fertility was significantly improved. Besides, the special sub-storied structure promoted the vegetation growth of under forest and improved the species diversity.(3) According to the study results and productive practice, fir-eucalyptus mixed forest and medium or long term rotation management with proper density and plowing, fertilizing could achieve large timber, Eucalyptus- acacia mixed forest and medium or short term rotation management could achieve the forest of plank stuff and pulpwood.(4) Because of different tree age, the fir-eucalyptus mixed forest could be only suitable for medium or long term rotation management. So the eucalyptus breed of small growth stress and strong corrosion is suitable for mixing with fir. As lower growth speed of acacia, the mass growth of mixed forest is lower than eucalyptus forest in short term so the cutting period could extend to 8 to 12 years. Not only the mass growth could be improved but also the soil fertility be promoted and huge economic, ecological and social benefits achieved.更多还原