水杉人工林细根寿命估计毕业论文_生态学毕业论文

水杉人工林细根寿命估计毕业论文

2021-04-27更新

摘 要

细根(直径≤2mm)是森林生态系统的重要组成部分,在树木水分和养分吸收、碳水化合物储存等方面发挥着重要作用。其寿命是指细根从出生到死亡的时间,是细根生理生态学特性的重要指标之一,是森林生态系统养分和C循环过程的核心环节。本文经过微根管方法现地观测水杉细根生长动态,通过生存分析方法来讨论细根形态(直径、根序)、土层深度和出世的时节对水杉细根寿命的影响。研究的结果表明:

1)细根的寿命与细根的直径和根序有着紧密的联系:直径等级逐渐提高,细根存活时间逐渐延长;而随着根序等级的提高,细根的寿命也逐步延长,累计存活率叶相应的提高。

2)细根寿命具备显著的季节规律性和土壤层次性:在季节性方面,水杉细根寿命的长短具体表现为春季<夏季<秋季。春季最短,而秋季最长;生长在土壤表层(0-15cm)的细根较生长在土壤深层的细根的寿命短,而随着土壤深度的不断增加,细根的寿命也越来越长。

关键词水杉人工林、生存分析、细根寿命、现地观测法

Estimation of fine root longevity in Metasequoia glyptostrobodies plantation

ABSTRACT

Fine root (diameter ≤ 2mm) is an important part of forest ecosystem, plays an important role in tree water and nutrient absorption, carbohydrate storage and so on. Root lifespan, the time from the birth to the death, is an important physiological and ecological characteristics of fine roots, and root lifespan is also the core part in the forest ecosystem nutrients and carbon cycle process. In this paper, the growth dynamics of fine root in Metasequoia glyptostroboides plantation was observed by minirhizotron method. We used survival analysis method to study the effects of fine root morphology (diameter, root order), soil depth and birth season on the root lifespan of Metasequoia glyptostroboides. The results of the study showed that:

1) Fine root longevity was closely related to fine root diameter and root order. The fine root lifespan gradually extended and the cumulative survival rate was improved with the increase of root diameter and order class.

2) Fine root longevity has obvious seasonal regularity and soil hierarchy. According to three seasonal root cohorts, the lifespan of autumn root cohort was longest and the lifespan of spring root cohorts was the shortest. The longevity of fine roots is prolonged with the increase of soil depth. The fine roots lifespan in the surface soil is the shorter than that in deeper soil.

Key words:Metasequoia glyptostrobodies, Survival analysis, Fine root longevity, In situ observation method.

目 录

1 前言………………………………………………………………1

1.1引言…………………………………………………………..1

1.2细根研究进展……………………………………………………1

1.2.1细根寿命的研究方法…………………………………………..1

1.2.2细根寿命的影响因素…………………………………………..3

1.3研究目的与意义………………………………………………….4

2 研究地概况与研究方法………………………………………………..5

2.1研究地概况……………………………………………………..5

2.2研究方法……………………………………………………….5

2.2.1样地设置……………………………………………………5

2.2.2仪器安装……………………………………………………6

2.2.3根系的影像收集与处理…………………………………………6

2.3统计分析方法……………………………………………………7

2.3.1细根寿命的比较方法…………………………………………..7

2.3.2细根寿命影响因子生存分析……………………………………..7

2.3.3细根寿命影响因子的检验……………………………………….8

3 结果与分析…………………………………………………………9

3.1细根总数量、直径、根序分布……………………………………….9

3.2细根总体寿命…………………………………………………..10

3.3细根直径与细根寿命……………………………………………..11

3.4细根根序与细根寿命……………………………………………..11

3.5细根土层分布与细根寿命………………………………………….12

3.6细根出生季节与细根寿命………………………………………….13

3.7对照样地不同影响因子对细根寿命的影响……………………………..14

3.8讨论………………………………………………………….15

3.8.1细根寿命与细根形态………………………………………….15

3.8.2细根寿命与出生季节………………………………………….15

3.8.3细根寿命与土层分布………………………………………….16

参考文献……………………………………………………………17

致谢……………………………………………………………….19

1 前言

1.1引言

根系是植物吸收水分和养分的功能器官,同时对树木又起到固定作用。在森林生态系统中,由于细根不断周转,有大批的C被耗费,并伴随着大量养分的释放。因而在森林生态系统的物质和养分循环环节中,细根起关键性的作用,且极易受到环境因素的影响。细根的生物量在大多数陆地生态系统中一般只占根系总生物量的3%-30%,但由于细根周转而导致树木每年的净初级生产力有10%-75%左右被消耗掉【1】。土壤有机质和营养元素的周转在忽略细根的生产、死亡和分解的情况下,将被低估20%-80%【2】。因而,细根生长、死亡的周转过程被认为是生态系统当中碳和养分循环过程中举足轻重的环节。细根寿命长短是细根周转率最直接的决定因子和最直观的体现。因而,关于不同树种细根寿命及其影响因素的探讨与研究,则在准确估计森林生态系统碳和养分循环过程中起着重要的作用【3-5】

1.2细根研究进展

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