连作杨树人工林土壤有机碳储量与碳循环过程研究

发布时间：2018-08-04 19:37

【摘要】：杨树是我国最重要的速生丰产树种,在缓解木材供需矛盾中发挥了重要的作用。然而在栽植面积快速增长的同时,杨树连作现象也越发普遍。连作会导致人工林地土壤养分有效性降低、微生物群落结构失衡,并加剧土壤的自毒效应,进而引起林分生产力下降,严重制约人工林的可持续发展。然而杨树连作是否会影响土壤碳储量与碳循环过程,目前尚不清楚。基于此,本研究以大汶河沿岸沙地不同连作代数(一代林、二代林和三代林)I-107杨树人工林生态系统为研究对象,采用空间代替时间的研究方法,从土壤碳含量和碳储量、土壤酶活性、凋落物分解以及土壤呼吸及其组分等方面探讨连作杨树人工林的土壤碳过程,重点阐明土壤碳循环过程的影响因子,揭示连作对杨树人工林土壤碳循环的影响机制。本研究从土壤碳循环角度探究杨树人工林的连作效应。研究成果可为全面探究杨树人工林碳固持和连作障碍提供基础数据,同时为杨树人工林地力维持和可持续经营提供科学依据。主要研究结论如下:(1)三种不同连作代数杨树人工林生态系统土壤有机碳含量和微生物量碳含量在0~100cm土壤深度内随土层的加深而减少,杨树人工林连作使土壤上层(0~40cm)的有机碳含量和微生物量碳含量显著减少,而对深层土壤(60~100cm)无显著影响。连作会导致土壤理化性质和养分含量下降,造成林地养分亏缺。杨树人工林种植提高了土壤脲酶、过氧化氢酶以及?-葡萄糖苷酶活性,杨树人工林连作则降低了土壤蔗糖酶、脲酶以及?-葡萄糖苷酶活性,反而提高了过氧化氢酶活性。(2)杨树人工林连作同时降低了凋落叶和细根的分解速率。凋落叶和细根在1a内的分解速率均呈现出明显慢-快-慢的阶段性特征。杨树细根的分解速率快于凋落叶,其达到95%的分解率分别大致需要3.3a和4.06a;土壤有机碳含量、土壤微生物量碳含量以及土壤?-葡萄糖苷酶活性显著影响两种类型凋落物的分解速率。(3)三种林分RS、RA和RH的日变化和月变化均呈现出明显的单峰格局;RA平均贡献率为40.04%,且存在季节差异;土壤呼吸速率及其各组分与5cm处土壤温度存在显著的指数关系,与土壤含水量之间没有相关性,同时包含土壤温湿度的幂-指数模型能够更好地表示土壤呼吸速率与土壤温湿度的关系,RA的温度敏感性(Q10)大于RH;连作抑制了杨树人工林的RS和RH,连作过后土壤理化性质和微生物生物量的下降是导致其土壤呼吸速率差异的主要原因。(4)三种林分土壤SOCR和MBCR均随连作代数的增加而减小。连作条件下,三种林分土壤生态系统均表现为“碳汇”,杨树人工林连作不利于土壤有机碳的积累和碳贮存。凋落物分解是人工林土壤养分的主要来源,杨树连作减少了林地土壤碳输入,同时降低了林地土壤呼吸速率以及凋落物分解速率,在抑制土壤碳周转的同时减缓了养分释放效率和强度,致使林地土壤养分供应不足,造成林地养分亏缺,进而导致林地生产力下降。因此,杨树连作不利于林地生产力的提高,在杨树人工林的经营过程中,应尽量避免连作经营,并采取人工施加有机肥等措施缓解连作障碍。
[Abstract]:Poplar is the most important fast-growing and high yield tree species in China. It plays an important role in alleviating the contradiction between supply and demand of wood. However, the continuous cropping of poplar is more common when the planting area is growing rapidly. Continuous cropping will lead to the decrease of soil nutrient availability, the imbalance of microbial community structure and the self toxic effect of soil, and then the self toxicity effect of soil is aggravated. However, it is not clear whether the poplar continuous cropping will affect the soil carbon storage and carbon cycle process. Based on this, this study takes the I-107 poplar plantation ecosystem of different continuous cropping Algebras (one generation forest, two generation forest and three generation forest) on the sandy land along the great Wen River, and takes the ecological system of poplar plantation as the research object. The soil carbon content and carbon storage, soil enzyme activity, litter decomposition and soil respiration and its composition were discussed with space instead of time. The influence factors of soil carbon cycle in soil carbon cycle were clarified, and the influence mechanism of continuous cropping on soil carbon cycle in poplar plantation was revealed. The research results can provide basic data for the comprehensive exploration of carbon fixation and continuous cropping barriers of poplar plantation, and provide a scientific basis for the maintenance and sustainable management of poplar artificial forestland. The main conclusions are as follows: (1) three different continuous cropping algebraic poplar artificial Lin Sheng Soil organic carbon content and microbial biomass carbon content decreased with soil depth in 0~100cm soil depth. Poplar plantation continuous cropping reduced soil organic carbon content and microbial biomass carbon content significantly, but had no significant effect on deep soil (60~100cm). Continuous cropping would lead to soil physical and chemical properties and nutrient content. Soil urease, catalase and glucosidase activity were increased by plantation of poplar plantation, and the activity of sucrase, urease and glucosidase in the poplar plantation decreased, but increased the activity of catalase. (2) the continuous cropping of Poplar Plantation decreased the litter and fine roots simultaneously. The decomposition rate of the litter and fine roots in the 1A showed a distinct slow fast slow phase characteristic. The decomposition rate of the fine root of the poplar was faster than that of the litters. The 95% decomposition rate of the poplar was approximately 3.3a and 4.06a, respectively, and the soil organic carbon content, soil microbial biomass carbon content and soil glucosidase activity were significantly affected. The decomposition rate of two types of litter. (3) the diurnal and monthly changes of the three species of RS, RA and RH all showed an obvious single peak pattern; the average contribution rate of RA was 40.04%, and there was a seasonal difference; the soil respiration rate and its components were significantly related to the soil temperature at 5cm, and there was no correlation with the soil water content. The power exponential model containing soil temperature and humidity can better indicate the relationship between soil respiration rate and soil temperature and humidity, the temperature sensitivity of RA (Q10) is greater than RH, and continuous cropping inhibits the RS and RH of poplar plantation. After continuous cropping, the decrease of soil physical and chemical properties and microbial biomass is the main reason for the difference of soil respiration rate. (4) The SOCR and MBCR of the three stand soil decreased with the increase of continuous cropping algebra. Under continuous cropping, the soil ecosystem of the three stands was "carbon sink". The continuous cropping of poplar plantation was not beneficial to the accumulation of soil organic carbon and carbon storage. Litter decomposition was the main source of soil nutrients in the plantation, and the poplar continuous cropping reduced the soil carbon transport in the forest soil. At the same time, the soil respiration rate and litter decomposition rate decreased, while the soil carbon turnover was inhibited and the nutrient release efficiency and intensity were slowed down, which resulted in the lack of nutrient supply in the woodland soil, resulting in the loss of woodland nutrient and the decline of the productivity of woodland. Therefore, the poplar continuous cropping was not conducive to the increase of woodland productivity, and in poplar trees. In the process of plantation management, continuous cropping management should be avoided as much as possible, and measures such as artificial application of organic fertilizer should be adopted to alleviate continuous cropping obstacles.
【学位授予单位】：山东农业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：S714

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