锐齿栎林年龄序列土壤呼吸组分特征研究

Characteristics of soil respiration components in the Quercus aliena var. acuteserrata forest chronosequence

关键词:  林龄, 自养呼吸, 异养呼吸, 土壤, 温度, 土壤特性

Key words:  forest age, rhizospheric respiration, heterotrophic respiration, soil temperature, soil properties

摘要:

林龄作为影响土壤呼吸的因素已是碳循环关注的热点问题之一,且林龄在模拟演替及长期碳动态的监测过程中发挥重要作用。该研究采用Li-Co-r8100土壤呼吸仪,研究林龄对土壤呼吸通量及其组分的影响。结果表明:锐齿栎林年龄序列(40 a, 80 a, >160 a)及不同组分的土壤呼吸速率都表现出明显的单峰型季节动态,且与5 cm土壤温度呈显著指数相关。这可能是由于温度变化影响土壤生物活性引起的,土壤温度与土壤呼吸关系的指数方程可以解释80%以上的土壤呼吸变化。土壤呼吸及其不同组分在林龄间均无明显差异,土壤呼吸对温度的敏感性在锐齿栎林年龄序列及各组分间也无显著差异,这可能与林龄间土壤特性、森林生产力、微环境条件等相差不大有关。加倍凋落物的累计土壤呼吸通量显著(P<0.05)高于对照、断根和去除凋落物处理的累积呼吸量,说明增加凋落物输入为土壤提供了更丰富的养分,改善了样地微环境,有利于激发土壤微生物活性。锐齿栎林累计土壤呼吸通量与土壤有机碳(SOC)、细根生物量(FR)和微生物呼吸(MR)也显著相关,表明该地区土壤特性以及地下新陈代谢能很好地解释锐齿栎林土壤呼吸格局。

Abstract:

The forest age as a factor affecting soil respiration is one of the hot issues in the carbon cycle, and forest age also plays an important role in simulating succession and monitoring the long-term carbon dynamic. We investigated soil respiration dynamics and characteristics in warm-temperate oak chronosequence in China, and measured soil respiration with a Li-Cor infrared gas analysis. We studied the effects of forest age on soil respiration flux and different components of Quercus aliena. The results showed that the seasonal patterns of soil respiration among the age classes of Q. aliena var. acuteserrata forest(40 a, 80 a, >160 a)and different components showed the obvious seasonal dynamics, and occurred as a unimodal curve. Soil respiration rate had a significantly exponential correlation to 5 cm soil temperature. This also could be explained by the effects of temperature on the activity of soil organisms. The exponential equations of soil temperature and soil respiration accounted for more than 80% of the variations in soil respiration rate. There was no significant variation in soil respiration and its components among different forest ages, and the sensitivity of soil respiration to temperature in different age chronosequence and soil components of Q. aliena var. acuteserrata forest also had no significant difference, which might be explained by the fact that there was no significant difference among the age classes of Q. aliena var. acuteserrata forest in soil properties, forest productivity and micro-environmental conditions. The cumulative soil respiration in treatment with doubled litter was significantly(P<0.05)higher than that of other components, which indicated that more litter could provide more abundant nutrient for the activity of soil microorganisms. There were also correlations of cumulative soil respiration with soil organic carbon(SOC), fine root biomass(FR)and microbial respiration(MR), which indicated that the soil properties and underground metabolism could well enough to explain the pattern of soil respiration among the age classes of Q. aliena var. acuteserrata forest in this region.