ISWC OpenIR  > 水保所2018--届毕业生论文
抚育间伐对油松人工林群落特征的影响
段梦成
Subtype硕士
Thesis Advisor王国梁
2015-06
Degree Grantor中国科学院研究生院
Place of Conferral北京
Keyword间伐 植物群落 更新 人工林碳储量 微生物群落
Abstract抚育间伐是人工林近自然经营的重要方式,研究间伐对人工林群落的影响,实践上,可为发展不同管理目标的人工林提供决策依据;理论上,探讨间伐对微生物群落的影响及机制,有助于认识群落变化的生物和非生物学过程,对于评价抚育间伐下的人工林生态服务功能具有重要意义。然而,目前关于间伐对人工林植物和微生物群落的影响以及驱动因素仍不清楚,制约了人们对生态过程和机制的认识以及森林管理措施的运用。本论文以子午岭林区54年林龄的油松人工林为对象,研究了四种间伐强度{保留密度800(强度),1500(中度),2200(轻度)和2900株/hm2(对照)}对油松人工林植物群落特征、土壤性质和微生物特征的影响及影响因素。主要研究结果表明:
(1)间伐强度影响植物群落特征。强度间伐下油松乔木径级最大,林分空间结构最优,植物多样性最高,中度间伐次之,轻度间伐最差。冠层郁闭度和地面叶凋落物厚度是影响林下物种组成的主要原因。此外,强度间伐下的辽东栎幼苗幼树更新状态最佳,有利于人工林向近自然林(针阔混交林)过渡,这对指导人工林的近自然经营有重大意义。虽然中度间伐下油松幼苗幼树更新状况最佳,但是,油松林内尚未出现大径级油松幼树,其能否正常更新还需持续长期的定位观测。
(2)中度和强度间对土壤性质有明显改善作用。虽然中度和强度间伐下土壤表层SOC含量 ( 14.18和13.41 g/kg)较对照(17.14 g/kg)有显著降低,不利于土壤碳固存,但却能提高了土壤表层含水量、EOC和全磷含量,降低土壤容重和碳氮比,有利于改善土壤质量。此外,中度和强度间伐显著降低了与碳氮磷循环相关的四种水解酶的活性,因为该间伐强度下易变组分在增加,减少了微生物在资源获取方面的投资。
(3)轻度和中度间伐能显著增加人工林碳储量,其中,轻度间伐下油松人工林生态系统碳储量最高(217.57 t/hm2),中度间伐次之(205.37 t/hm2)。乔木层是人工林生态系统中最大的碳库,轻度和中度间伐下其储量占人工林总碳储量
73.21%和74.62%,是人工林系统碳储量增加的主要原因,土壤层碳储量的降低是强度间伐下人工林碳储量减少的主要原因。尽管中度和强度间伐叶凋落物的现存量较对照显著减少了34.34%和51.85%,但林下灌草生物量却显著增加了,对森林碳汇有一定的补偿作用。
(4)不同间伐强度对微生物群落影响不同。间伐对总的微生物含量影响不大,但却改变了微生物群落组成,如中度和强度间伐真菌含量(1.07和1.31 nmol/g)显著低于对照和轻度间伐(2.46和1.85 nmol/g),真菌细菌比也表现出相同规律。微生物群落多样性呈随间伐强度增加呈先减后增趋势,且强度间伐下(2.92)恢复到间伐之前的水平(2.98),这对维持黄土高原土壤生态系统的稳定性和活性具有重要意义。植物多样性的增加以及SOC含量变化是微生物群落特征变化的关键。
本研究发现,强度间伐不仅能优化人工林群落结构,增加植物多样性和促进乡土物种更新,还能够改善土壤理化性质,增加土壤微生物多样性;轻度间伐是发展碳汇人工林的最佳间伐强度,中度间伐次之。该研究结果对黄土高原油松林管理具有参考价值。
Other AbstractTending thinning is an important way for near-natural management of plantations. Studying the impacts of thinning on artificial forest communities can practically provide decision-making basis for the development of planted forests with different management objectives; theoretically, exploring the effects and mechanisms of thinning on plantation communities is conducive to comprehend the biological and non-biological processes, which has a profound implication for evaluating the ecological service functions of the plantations under the thinning. However, the influence and driving factors of thinning on plant and microbial communities are still unclear, restricting people's knowledge of ecological processes and mechanisms and the execusion of forest management measures. In this study, by taking the 54 stand age Pinus tabulaeformis plantations with the following four reserved densities 800(heavy), 1500(medium), 2200(light) and 2900(unthinning) stems/hm2 after tending thinning in the Ziwuling area of ​​Loess Plateau as the research objects, we analyzed effects of thinning on plant community, soil characteristics and microbial community and their influencing factors. Our main research results showed that:
(1) Thinning intensity affected plant community characteristics. Under heavy thinning, Pinus tabulaeformis had the largest tree size, the spatial structure of the forest was the optimal, the plant diversity was the highest, the medium thinning was the second, and the light thinning was the worst. Canopy closure and litter thickness was the main reason affecting the understory species composition. In addition, the regeneration status of the seedlings and saplings of Quercus liaotungensis under heavy thinning is best, contributing to the transition from artificial forests to near-natural forests (coniferous and broad-leaved mixed forests), which is of great significance in guiding the near-natural management of plantations. Although there was a better renewal of Pinus tabulaeformis under medium thinning, a long-term observations are required, for large-diameter pine young trees have not yet emerged in the forest.
(2)Both of medium and heavy thinning significantly improved soil properties. Although the soil surface SOC content (14.18 and 13.41 g/kg) was significantly lower than that of the control (17.14 g/kg) under medium and heavy thinning, it could increase soil surface water content, EOC and Total phosphorus content, reduced soil bulk density and carbon-nitrogen ratio, consequently improving soil quality. In addition, medium and heavy thinning significantly reduced the activity of the four hydrolase enzymes associated with the carbon, nitrogen, and phosphorus cycle, as the liable components increased at the thinning intensity, decreasing microbial investment in resource acquisition.
(3)Light and medium thinning can significantly increase the carbon storage of plantations, of which, the light thinning is the highest (217.57 t/hm2) in ecosystem ecosystem of Pinus tabulaeformis plantation, followed by medium thinning (205.37 t/hm2). The arboreal layer was the largest carbon pool in the plantation ecosystem, which accounted for 73.21% and 74.62% of the total carbon storage of the plantation under light and medium thinning, which is the main reason for the increase of carbon storage in the plantation system,but reduction in soil layer is the main reason for the decrease in carbon stocks under heavy thinning. Although the existing amount of leaf litter under medium and heavy thinning decreased by 34.34% and 51.85% compared with the control, the biomass of understory shrubs increased significantly, which had a certain compensatory effect on forest carbon sinks.
(4) Different thinning intensities have different effects on microbial communities. Thinning had slight effect on the total microbial content, but changed the microbial community composition, such as fungi (1.07 and 1.31 nmol/g) under medium and heavy thinning was significantly lower than the control and light thinning (2.46 and 1.85 nmol/g). The fungal bacteria ratio also showed the same pattern. The diversity of microbial community showed a trend of decreasing first and then increasing with the increase of the thinning intensity, and the heavy thinning (2.92) recovered to the level of unthinning (2.98), which is of great significance for maintaining the stability and activity of the soil ecosystem in the Loess Plateau. The increase of plant diversity and the change of SOC were driving forces to the change of microbial community characteristics.
This study found that heavy thinning can not only optimize the community structure of plantation, increase plant diversity and promote native species regeneration, but also improve soil physical and chemical properties and increase soil microbial diversity; light thinning is the best way to develop carbon sink plantations, followed by medium thinning. The research results have reference value for the management of Pinus tabulaeformis plantation in Loess Plateau.
Subject Area生态学
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/8145
Collection水保所2018--届毕业生论文
Affiliation中国科学院大学
Recommended Citation
GB/T 7714
段梦成. 抚育间伐对油松人工林群落特征的影响[D]. 北京. 中国科学院研究生院,2015.
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