黄土高原油松人工林对土壤酶活性及微生物的影响

发布时间：2018-03-17 01:01

本文选题：油松人工林　切入点：土壤酶活性　出处：《西北农林科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：油松作为黄土高原地区的先锋树种,因其具有耐寒、耐旱和耐贫瘠的特性而被作为主要的人工作林树种广泛栽植。前期对油松的研究已经发现,油松造林后随着林龄的增加土壤理化性质会发生一系列变化,这些变化对土壤的微生物活性,土壤酶活性都会产生深刻的影响,进而影响林木的生长和幼苗更新。但是这方面的研究还很欠缺,尤其是有关影响机制的研究。本研究旨在揭示油松人工林对土壤酶活性和微生物生的影响及其季节变化,为油松人工林的可持续管理提供依据。本研究的研究地点位于黄土高原子午岭林区的富县和尚塬林场。分别选择8年生(PF8)、22年生(PF22)和42年生(PF42)的油松人工林,以及大约70年林龄的油松天然次生林(NSF)。每种类型林分设置3个20m×20m的标准样地.在标准样地内按照S型采集土壤样品。土壤样品主要测定土壤理化性质,土壤酶活性和土壤微生物量碳氮等三方面的指标。幼苗更新选择成熟人工林(PF42)和天然次生林(NF)进行调查。研究发现林龄和季节对除全氮以外的其他土壤指标均有显著的影。土壤pH、全氮、有机碳和全磷含量在夏季最高,而土壤碳氮比在秋季最高。土壤理化性质在油松人工林不同阶段的变化规律不同。比如,土壤容重、温度、硝态氮、铵态氮、全氮、全磷和速效磷含量随林龄增长而下降;而土壤含水量孔隙度、全钾、速效钾和有机碳随林龄增加而逐渐提高。油松天然次生林土壤营养元素的含量均高于油松人工林,随季节的变化规律是夏季和秋季高于春季和冬季。油松林土壤微生物量碳和氮含量均表现为夏季高于秋季、春季和冬季.其原因可以理解为:植物在夏季具有较强的光合能力,促使根系分泌更多的碳水化合物,进而激发土壤微生物的活性增强。油松人工林土壤微生物量碳含量在8年林地最低,在22年林地达到最高值,而到42年时有所下降。油松人工林土壤微生物量碳的含量从8年到22年迅速提高,而到PF42又有所下降说明土壤微生物量碳的累积主要在油松人工林的幼龄林到中龄林阶段。土壤微生物量氮含量却随年龄增长而下降。土壤微生物量氮的持续下降的原因主要是温带森林土壤氮较高的矿化率和淋溶作用。土壤微生物量碳和氮含量在天然次生林均高于不同林龄的人工林,而Cmic/Nmic、Cmic/SOC、和Nmic/TN在天然次生林均低于不同林龄人工林。对于油松人工林,Cmic/SOC和Nmic/TN值在22年林地最高。土壤蔗糖酶、碱性磷酸酶、脲酶和过氧化物酶的活性在植物光合作用活性达到峰值的夏季均高于其他季节。土壤脲酶和蔗糖酶活性在四个季节均有显著差异,碱性磷酸酶活性在春季和夏季有显著差异。此外,土壤脲酶、蔗糖酶和碱性磷酸酶在油松人工林不同林龄阶段均有显著的变化。比如,脲酶活性随林龄的增长而降低,碱性磷酸酶活性随林龄的增长而提高,然而蔗糖酶活性在22年的林地达到最高,到42年时有所下降。与人工林相比,土壤脲酶、碱性磷酸酶和蔗糖酶活性在天然次生林相对较高。土壤微生物活性与土壤理化性质的相关性在不同季节的表现不尽相同。在春季,所测四种酶活性指标均与土壤理化性质存在显著相关性。然而,土壤理化性质与过氧化物酶活性在夏季和秋季无显著相关性,与蔗糖酶、脲酶和碱性磷酸酶存在显著相关性。土壤微生物量氮和全氮在四个季节均有显著的相关性,而土壤微生物量碳和有机碳在冬季没有显著相关性,在其他三个季节有显著相关。42年生油松人工林林下幼苗数量为244株/375m2,其中10年以上的幼苗占大约4%。而天然次生林的幼苗数量为547株/375m2,其中年龄大于10的幼苗数量占16%。天然次生林林下幼苗更新能力明显强于油松人工林。说明油松天然次生林相比人工林可为幼苗的生长发育提供较好的生境和土壤条件。通过冗余分析可知,掉落物厚度层、植物覆盖度、pH、土壤含水量、土壤有机碳、氨态氮、速效磷、全磷、速效钾、全钾、脲酶、蔗糖酶、微生物量碳、微生物量氮等因子与油松幼苗更新显著相关,揭示了油松林发育过程中,土壤特征对幼苗更新有非常重要的影响。综上所述,油松林土壤理化性质、微生物量碳、微生物量氮、土壤酶活性随季节变化和林龄的增长均有显著的变化(p0.05)。土壤微生物量碳和氮含量在夏季和秋季显著高于春季和冬季。随着林玲变化土壤微生物量碳在油松人工林不同发育阶段实现上升后下降,土壤微生物量氮随着林玲下降。土壤脲酶、碱性磷酸酶、蔗糖酶和过氧化物酶活性在夏季显著高于其他季节。与油松人工林相比,天然次生林土壤脲酶、碱性磷酸酶和蔗糖酶活性较高。土壤微生物活性与土壤理化性质的相关性在不同季节的表现不尽相同。土壤微生物量氮和全氮在四个季节均有显著的相关性,而土壤微生物量碳和有机碳在冬季没有显著相关性,在其他三个季节有显著相关。林下幼苗更新数量和年龄结构多样性在油松天然次生林高于人工林。因此说在黄土高原地区油松天然次生林生态系统在维持土壤质量方面优于油松人工林。因此,在黄土高原油松人工林经营过程中,以天然次生林生态系统为参考,进一步对人工林实施近自然经营措施,对人工林生态系统包括土壤生态系统的可持续发展有很重要的意义。
[Abstract]:As a pioneer species of Pinus tabulaeformis in the Loess Plateau, because of its cold, drought and barren resistance characteristics were as the main work forest tree species widely cultivated. Preliminary study on Pinus tabulaeformis have found that pine after afforestation increased with forest age and soil physical and chemical properties have a series of changes, these changes on Soil microbial activity the soil enzyme activity will have a profound impact, thereby affecting the growth of trees and seedlings. But this research is still lacking, especially the research on the influence mechanism. This study aims to reveal the influence of Pinus tabulaeformis Plantation on soil enzyme activity and microbe and its seasonal changes, provide the basis for the sustainable management of Pinus tabulaeformis plantation. The study site is located in the Loess Plateau, the plateau Fuxian Ziwuling forest. Monks were selected in 8 years old (PF8), 22 years (PF22) and 42 years (PF42). Pinus tabulaeformis Plantation and natural forest of Pinus tabulaeformis, about 70 years of age (NSF). The standard samples of each type of stand set 3 20m * 20m. In the standard plots in type S soil samples were collected. The soil samples were mainly determined soil physical and chemical properties, soil enzyme activity and soil microbial biomass carbon and nitrogen in three the seedling index. Select the mature plantation and natural forest (PF42) (NF) were investigated. The study found that the age and season on the other soil indexes were significant except total nitrogen outside. Soil pH, total nitrogen, organic carbon and phosphorus content in summer is the highest, and the soil carbon nitrogen ratio is the highest in autumn. The physical and chemical properties of soil in Pinus tabulaeformis Plantation in different stages is different. For example, the soil bulk density, temperature, nitrate nitrogen, ammonium nitrogen, total nitrogen, total phosphorus and available phosphorus content decreased with the increase of age; while the water content of soil porosity, total potassium, available potassium and The organic carbon increased gradually with the increase of forest age. The content of Pinus tabulaeformis natural forest soil nutrient elements were higher than that of Pinus tabulaeformis plantation, the seasonal variation law is in summer and autumn than in spring and winter. Pine soil microbial biomass carbon and nitrogen content were higher in summer than in autumn, spring and winter. The reason can be understood as: the plant has strong photosynthetic capacity in the summer, to root secrete more carbohydrates, enhance and stimulate soil microbial activity of Pinus tabulaeformis plantation. Soil microbial biomass carbon content in 8 years in 22 years of woodland, woodland reached the highest value, and by the 42 year decline. The content of soil microbial biomass carbon in Pinus tabulaeformis plantation from 8 years to 22 years to improve rapidly, and PF42 decreased that accumulation of soil microbial biomass carbon in Pinus tabulaeformis Plantation to forest stage. The soil microbial biomass nitrogen The amount was decreased with age. The reason for declining soil microbial biomass nitrogen is mainly temperate forest soil nitrogen mineralization rate and higher leaching. Soil microbial biomass carbon and nitrogen content were higher than those of different ages in the natural secondary forest and plantation, Cmic/Nmic, Cmic/SOC, and Nmic/TN in the natural secondary forest were lower than those of different the age of plantation. The plantation of Pinus tabulaeformis, Cmic/SOC and Nmic/TN in 22 years. The highest value of woodland soil invertase, alkaline phosphatase, urease and peroxidase activity in plant photosynthesis activity reached the peak of the summer season. He was higher than the soil urease and invertase activity in the four seasons had significant differences, there are significant differences in the the spring and summer of alkaline phosphatase activity. In addition, the changes of soil urease, invertase and alkaline phosphatase in different age stages of Pinus tabulaeformis Plantation significantly. For example, urease activity Decreased with age increasing, alkaline phosphatase activity increased with the age increasing, but the invertase activity in the 22 years of woodland reached the highest in 42 years decreased. Compared with the plantation soil urease, alkaline phosphatase and invertase activity was relatively high in natural secondary forest. The relationship between physicochemical properties of soil microbial activity and the soil is not the same in different seasons. In spring, the four kinds of enzyme activity index had significant correlation with soil physicochemical properties. However, soil physicochemical properties and peroxidase activity in summer and fall, no significant correlation with invertase, urease and alkaline phosphatase in soil were significantly correlated. Microbial biomass nitrogen and total nitrogen in four seasons had significant correlation, and soil microbial biomass and organic carbon had no significant correlation in the winter, in the other three seasons were significantly related to.42 years old The number of Pinus tabulaeformis seedlings under Lin Lin for 244 strains of /375m2, of which 10 years of seedlings accounted for about 4%. and the number of natural forest seedlings was 547 plants /375m2, the age of more than 10 seedlings accounted for 16%. of natural secondary Lin Lin seedlings was stronger than that of natural forest of Pinus tabulaeformis Plantation. Pinus tabulaeformis plantation can provide better than the habitat and soil conditions for the growth and development of seedlings. Through redundancy analysis, falling object thickness, plant coverage, pH, soil moisture, soil organic carbon, ammonia nitrogen, available phosphorus, total phosphorus, available potassium, total potassium, urease, invertase, microbial biomass carbon, microbial biomass nitrogen update factor and pine seedlings significantly correlated, reveals the process of Pinus tabulaeformis forest development, soil characteristics has very important influence on seedling regeneration. In summary, the physicochemical properties of Pinus tabulaeformis forest soil, microbial biomass carbon, microbial biomass, soil enzyme Changes in the growth of activity changes with the seasons and age were significantly (P0.05). Soil microbial biomass carbon and nitrogen content in summer and autumn was significantly higher than that in spring and winter. Along with the changes of soil microbial biomass carbon Lin Ling in Pinus tabulaeformis Plantation in different developmental stages to achieve increased and then decreased, soil microbial biomass nitrogen with Lin Ling decreased. Soil Urease Activities. Alkaline phosphatase, invertase and peroxidase activity in summer was significantly higher than that in other seasons. Compared with the natural secondary forest of Pinus tabulaeformis plantation, soil urease, alkaline phosphatase and invertase activity. The higher correlation between the physicochemical properties of soil microbial activity and soil vary in different seasons. Soil microbial biomass nitrogen and total nitrogen in the correlation between the four the season was significantly, while soil microbial biomass and organic carbon had no significant correlation in the winter, in the other three seasons are significantly related. The young forest Update the seedling number and age structure of diversity in natural secondary forest was higher than that of the plantation of Pinus tabulaeformis. So that in the Loess Plateau area of secondary natural Pinus tabulaeformis forest ecosystem in maintaining soil quality is better than that of Pinus tabulaeformis Plantation in Loess Plateau. Therefore, Chinese pine plantation management process in natural secondary forest ecosystem for reference, further implementation of near natural management measures on the plantation, the plantation ecosystem including the sustainable development of soil ecosystem has very important significance.

【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S714.3

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