【作者】 赵一鹤；

【导师】 杨宇明；

【作者基本信息】 中国林业科学研究院 ， 生态学， 2008， 博士

【摘要】 大面积种植桉树(Eucalyptus spp.)对生物多样性影响的问题不容忽视,本研究在云南省普洱市巨尾桉工业原料林内设置了样地89块,并在其邻近相似条件下设立了巨尾桉工业原料林原植物群落样地(参照)8块,采用群落学调查方法和土壤分析,α多样性测度方法和应用SPSS软件进行统计分析,探讨了巨尾桉工业原料林的群落结构,重点阐述了林下植物物种多样性变化特征、影响因子及作用规律,并进行了巨尾桉工业原料林与原植物群落林下植物物种多样性的对比分析与评价,为提高巨尾桉工业原料林林下植物物种多样性,以及可持续经营提供理论依据。在云南南部南亚热带山地环境条件下,巨尾桉工业原料林中幼林下伴生植物物种多样性虽较高,但物种组成特征表现为以阳生性先锋植物和适应性强的广布旱生植物物种为主,多属次生成分和外来物种,特别是一些新侵入的种类,而原植物群落的林下植物物种成分在巨尾桉工业原料林中较少。这主要是由于巨尾桉工业原料林营建后,改变了原植物群落的光照和水分等生态因子,与外来物种的生物学特性相适应,加之外来物种的入侵性和扩散性较强,这样就为外来物种的入侵创造了条件,使外来物种入侵的机会增加,造成了草本层的主要种类以紫茎泽兰、飞机草等外来入侵物种占优势,并成为群落内主要的伴生种类。阐明了巨尾桉工业原料林林下植物物种多样性的特征和变化规律,在研究区域范围内,林下植物物种丰富度表现为草本层大于灌木层,多样性指数和均匀度指数则是灌木层大于草本层。这主要反映了巨尾桉工业原料林群落内部存在的空间异质性,草本层以次生性或入侵优势种明显,形成单优种群,灌木层植物则表现不明显,反映了南亚热带次生性草本植物适应性较强,在人工干预后很快进入新建群落,并形成优势;灌木多属原有成分,对生境要求较严格,在人为干预下,恢复较次生性草本植物要缓慢。定量的研究和分析了物种多样性与不同因子的相关性,明确提出了立地条件是影响林下植物物种多样性的关键因子,立地因子中土壤类型是影响巨尾桉工业原料林林下植物物种多样性最为关键的因子,赤红壤对物种丰富度影响较大,黄棕壤对物种多样性指数影响较大。坡向也是影响巨尾桉工业原料林林下植物物种多样性的重要立地因子,与草本层的Simpson指数相关性达到显著水平。因此,在滇南南亚热带山地环境条件下,经营巨尾桉工业原料林不能象平原地区采用统一的造林规划设计和技术方法,必须针对不同坡向和坡度,尽量避免在阴坡和>25°的陡坡上规模造林,另外把土壤类型作为巨尾桉工业原料林经营条件与实施措施的一项重要条件来考虑。论述了巨尾桉工业原料林林下植物物种多样性与土壤肥力关系较密切,明确提出了土壤有机质含量是影响林下物种多样性的最为关键因子,水解性N的含量是影响林下物种多样性的重要因子。为了保持林下土壤肥力和提高林下植物物种多样性,构建高物种多样性的稳定生态系统,结合土壤性质,进行科学合理施肥。由于滇南南亚热带山地从山谷、山坡到山脊约1000m的高差范围内,广泛分布着季风常绿阔叶林、针阔混交林、思茅松林和热性灌草丛。规模化营造巨尾桉工业原料林替代原有的天然或半自然植被,对滇南南亚热带山地植物生态系统多样性和物种多样性带来明显的影响,主要表现在:在原南部南亚热带山地植被垂直带的多样化植被生态系统类型变为单一的人工植被类型,即生态系统多样性受到影响;由原含有丰富物种多样性的天然或半自然植被生态系统被单一的人工植被替代,其林下植物物种多样性发生明显改变,物种丰富度减少和多样性指数降低。因此,在生态系统和物种多样性丰富的云南南部南亚热带山地,不破坏原有天然植被或仅开发少量次生性灌丛地,并选择适宜的坡向、土壤类型,同时采取适地适树,营造混交林,保留天然植被走廊和控制林分密度等措施,将对林下植物物种多样性的影响降到最低,促进巨尾桉工业原料林林下植物物多样性的提高,以达到可持续经营的目的。从物种丰富度、物种多样性、外来入侵物种、林下植被生物量和覆盖度5个方面,对巨尾桉工业原料林林下植物物种多样性进行评价指标的选择和标准的研究,形成综合值为75分,其理论检验结果显示巨尾桉工业原料林林下物种多样性程度与实际情况相符,说明所提出的评价标准与指标是科学和客观的。因此,本研究提出的评价标准与指标可以评价判断巨尾桉工业原料林林下植物物种多样性,有助于在规划、设计、造林和经营管理过程中注意林下植物物种多样性的恢复和改善问题。更多还原

【Abstract】 Mass plantation of Eucalyptus spp. has significant impacts on local biodiversity. In this study,89 plots of E. grandis×E. urophylla in the a industrial plantation and 8 plots of original communities were compared in similar, adjacent stands set up in Puer City, Yunnan Province. Synecology sampling, soil analysis, andαbiodiversity data were analyzed using the software SPSS. The community structure of the E. grandis×E. urophylla industrial plantation and the undergrowth’s biodiversity changes, patterns, and driving factors were discussed. A comparison study of biodiversity in the original endemic communities and the E. grandis×E. urophylla communities was carried out. The findings of the study will provide theoretical support for improving under-forest biodiversity of artificial E. grandis×E. urophylla forests and their sustainable management.In the subtropical mountains of southern Yunnan, undergrowth’s species diversity of young-middle stands of artificial E. grandis×E. urophylla forests can be very high. However, a large portion of the species composition is composed of pioneer heliophyte, adaptable dispersed species, secondary and exotic species. Original elements of the endemic floristic composition are rarely found in undergrowth of E. grandis×E. urophylla industrial plantation, largely due to the alternation of habitats during mass forestation. such as light and water ecological factors, to be accommodated with themselves bionomics. Additionally, these exotic species have strong diffusion and invasiveness. All above factors produced advantageous conditions for these exotic species to invade.At the same time, human disturbances have caused species invasion. Eupatorium adenophorum and Eupatorium odoratum etc. have already dominated the herbaceous layers and major companion species of regional communities.This paper summarizes the characters of the undergrowth species diversity and the changing patterns. Within the studied area, the herbaceous layer is generally higher than shrub layer in terms of undergrowth species richness and lower in terms of evenness and diversity. This shows the environmental heterogeneity of the E. grandis×E. urophylla plantation. The herbaceous layer was dominated by secondary and exotic species, forming a“consociation”. Yet the shrub layer lacks such dominant species. This shows that the secondary subtropical herb species have higher adaptability than shrubs, and can enter and dominate new communities after human disturbances. Compatibly, shrub genuses are stricter to their habitat. Their recovery after human disturbances is much slower than herbs.The correlation analysis of species diversity and environmental factors showed that the stand situation largely determines the undergrowth species diversity. The soil type is positively pertinent to the Simpson indicator of the herbaceous layer, Lateritic red soil has high impacts on species richness, while yellow-brown soil has high impacts on species biodiversity indicators.Another key factor is the aspect of a stand. showing that“aspect”is the most important factor that decides the undergrowth species diversity of E. grandis×E. urophylla forest。Thus, the forestation and management of E. grandis×E. urophylla in subtropical mountainous stands of south Yunnan should not have just one uniform plan, design and methodology, like that in big plains. It should be designed according to different aspects, slopes, and gradient. The forestation on slope >25°should be avoided. Additionally, soil type should also be taken as an important factor.Undergrowth species diversity of E. grandis×E. urophylla industrial plantation has a close relationship to soil fertility. The concentration of soil organic matter, especially the hydrolyzable nitrogen, is a key factor of undergrowth species diversity. In order to maintain the fertility of soil and improve the undergrowth species diversity, scientific and reasonable fertilization conforming to the characteristics of the soil will be important to build a stable ecosystem with high species diversity.A spectrum of monsoon evergreen broadleaved forests, mixed forests, Pinus kesiya var. langbianensis (Simao Pine) forests, and dry-hot shrub-grasslands are distributed along the great rivers and through the mountain ranges of the studied area, which has a 1000m elevation difference. Large scale forestation of E. grandis×E. urophylla forests for industrial purposes will replace the original natural or sub-natural vegetation and have the following large-scale impacts on local ecosystem and species diversity: 1) the original south-subtropical mountains have very diverse ecosystems, which will be lost and altered into unitary artificial vegetation. 2) The original natural or sub-natural vegetation with high species diversity will be replaced by artificial vegetation. The undergrowth species diversity will decrease with significant species richness and diversity loss.For South Yunnan’s mountains that have such high ecosystem and species diversity, there are several methods to delimitate the impacts of E. grandis×E. urophylla industrial plantation on undergrowth species diversity. For example, do not use the original forest land; use just a few of the secondary shrub lands; arrange different tree species for different aspects and soil types of the stand; build mixed forests; maintain the biological corridors; manage the stand density. The subsequent management will promote the undergrowth biodiversity preservation and realize the ultimate goal of“sustainable forest”.A species diversity assessment indicators system and the standards for the undergrowth of E. grandis×E. urophylla industrial plantation were set up using the following five factors: species richness, species diversity, importance value of exotic species, undergrowth vegetation biomass and coverage. The system was validated through case studies found to be scientifically sound. The proposed biodiversity assessment indicators system has provided a useful tool to assess the E. grandis×E. urophylla forestation, and to consider and involve the biodiversity amelioration and recovery issues during planning, forestry design, forestation and management of planting Eucalyptus forests.更多还原