黄土丘陵区油松、沙棘纯林及混交林土壤呼吸特征比较研究

发布时间：2018-01-07 18:38

本文关键词：黄土丘陵区油松、沙棘纯林及混交林土壤呼吸特征比较研究　出处：《中国科学院大学(中国科学院教育部水土保持与生态环境研究中心)》2017年硕士论文　论文类型：学位论文

【摘要】：土壤呼吸是二氧化碳(CO_2)通过土壤向大气释放的过程,是陆地生态系统碳素从土壤中以CO_2形式返回大气的主要途径。本研究在黄土丘陵区油松、沙棘纯林及二者混交林中分别设置了自然组(含凋落物)和去凋组(不含凋落物),通过对三种林分自然组与去凋组土壤呼吸、5cm土壤温度和含水量的监测,研究三种林分土壤呼吸特征的差异以及土壤温度、土壤含水量和地表凋落物对土壤呼吸的影响。在三种林分内分别设置20 m×20 m样地,样地内随机设置5个观测点,于2015年8月至2016年7月使用LI-8100系统进行监测。主要结论如下:1、油松纯林土壤呼吸动态特征(1)自然组与去凋组土壤呼吸具有相似的季节动态特征,最高值均出现在7月,最低值均出现在2月,冬季土壤呼吸量分别占全年呼吸总量的39.85%和60.70%。(2)凋落物呼吸对油松纯林土壤呼吸的贡献量为2.81 tCO_2/(hm2·a),占林分土壤总呼吸的10.91%,但土壤呼吸与凋落物积累量不存在相关性。(3)季节尺度油松纯林自然组与去凋组土壤呼吸与土壤温度及含水量均存在显著相关性(p0.05),土壤呼吸主要受土壤温度和含水量的共同作用,且凋落物显著提高了油松纯林土壤呼吸的温度敏感性(p0.05)。2、沙棘纯林土壤呼吸动态特征(1)自然组与去凋组土壤呼吸具有相似的季节特征,最高值均出现在7月,最低值均出现在2月,冬季土壤呼吸量分别占全年呼吸总量的29.65%和42.91%。(2)凋落物呼吸对沙棘纯林土壤呼吸的贡献量为10.38 tCO_2/(hm2·a),占林分土壤总呼吸的27.76%,且土壤呼吸与凋落物积累量存在显著线性正相关(p0.05)。(3)季节尺度沙棘纯林自然组与去凋组土壤呼吸与土壤温度及含水量均存在显著相关性(p0.05),土壤呼吸主要受到土壤温度和含水量的共同作用,且凋落物显著提高了沙棘纯林土壤呼吸年通量及温度敏感性(p0.05)。3、混交林土壤呼吸动态特征(1)自然组与去凋组土壤呼吸具有相似的季节特征,最高值均出现在7月,最低值均出现在2月,冬季土壤呼吸量分别占全年呼吸总量的40.24%和51.99%。(2)凋落物呼吸对混交林土壤呼吸的贡献量为7.25 tCO_2/(hm2·a),占林分土壤总呼吸的21.82%,土壤呼吸与凋落物积累量之间不存在显著相关性。(3)季节尺度混交林自然组与去凋组土壤呼吸与土壤温度及含水量均存在显著相关性(p0.05),土壤呼吸主要受到土壤温度和含水量的共同作用,且凋落物显著提高了混交林土壤呼吸温度敏感性(p0.05)。4、凋落物显著提高了沙棘纯林土壤呼吸的温度敏感性及土壤呼吸年通量,但对油松纯林及混交林仅显著提高了土壤呼吸温度敏感性,对土壤呼吸年通量并未显著提升。油松纯林及混交林作为黄土丘陵区水土保持及生态恢复的造林模式更有利于减缓该地区林地碳支出。
[Abstract]:Soil respiration is carbon dioxide (CO_2) released to the atmosphere through the soil, is the main way of terrestrial ecosystem carbon from the soil in the form of CO_2 returns to the atmosphere. This research in the loess hilly area of Pinus tabulaeformis, seabuckthorn pure forest and mixed forest in two were set up in a natural group (including litter and litter removal (Group) no litter), the three stand natural group and to 5cm group of soil respiration fades, soil moisture and temperature monitoring, the difference of three kinds of forest soil respiration and soil temperature, soil moisture and litter respiration effect on soil. Were set up in three forest in 20 m * 20 m plots, plots were set up 5 observation points, from August 2015 to July 2016 using the LI-8100 monitoring system. The main conclusions are as follows: 1. The characteristics of pure forest soil respiration of Pinus tabulaeformis (1) natural group and litter removal group had similar soil respiration Seasonal dynamic characteristics, the highest value appeared in July, the lowest value appeared in February, winter soil respiration accounted for 39.85% of the total annual respiration and 60.70%. (2) contribution to soil respiration of Pinus tabulaeformis forest litter respiration rate was 2.81 tCO_2/ (hm2 - a), accounting for 10.91% of the total soil respiration. But the soil respiration and litter accumulation was not correlated. (3) the seasonal scale natural Pinus tabulaeformis forest group and litter removal group of soil respiration and soil temperature and water content were significantly correlated (P0.05), soil respiration is mainly affected by soil temperature and moisture interaction, and litter significantly improves the temperature sensitivity of Pinus tabulaeformis pure forest soil respiration (P0.05.2), pure forest soil respiration characteristics of sea buckthorn (1) natural group and group to wither with the seasonal soil respiration characteristics is similar, the highest value appeared in July, the lowest value appeared in February, the amount of soil respiration in winter respectively. 29.65% of the total annual respiration and 42.91%. (2) contribution to soil respiration of seabuckthorn pure forest litter respiration rate was 10.38 tCO_2/ (hm2 - a), the total of 27.76% forest soil respiration, and soil respiration and litter accumulation had significant linear correlation (P0.05). (3) the seasonal scale of pure Seabuckthorn the natural forest group and litter removal group of soil respiration and soil temperature and water content were significantly correlated (P0.05), soil respiration is mainly affected by soil temperature and moisture interaction, and litter increased to breathe the pure forest soil flux and temperature sensitivity of sea buckthorn (P0.05.3), the dynamic characteristics of mixed forest soil respiration (1) natural group and group to wither with the seasonal soil respiration characteristics is similar, the highest value appeared in July, the lowest value appeared in February, winter soil respiration accounted for 40.24% of the total annual respiration and 51.99%. (2) litter respiration to soil respiration in mixed forest With suction quantity is 7.25 tCO_2/ (hm2 - a), the total respiration of forest soil in 21.82%, there is no significant correlation between soil respiration and litter accumulation. (3) the seasonal mixed forest natural group and litter removal group of soil respiration and soil temperature and water content were significantly correlated (P0.05). Soil respiration is mainly affected by soil temperature and moisture interaction, and litter mixed forest significantly improves the temperature sensitivity of soil respiration (P0.05.4), litter significantly improves the temperature sensitivity of soil respiration and soil respiration in Seabuckthorn plantations of Pinus tabulaeformis forest flux, but only significantly improved and mixed forest soil respiration the sensitivity of soil respiration flux has not significantly improved. Pure pine forest and mixed forest in loess hilly area of soil and water conservation and ecological restoration afforestation mode is more conducive to mitigate forest carbon expenditures in the region.

【学位授予单位】：中国科学院大学(中国科学院教育部水土保持与生态环境研究中心)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S714

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