IMHE OpenIR  > 山地表生过程与生态调控重点实验室
贡嘎山峨眉冷杉树干呼吸时空动态及其影响因子
Alternative TitleTemporal-spatial variation and controls of stem respiration of Abies fabri on Gongga Mountain
Language中文
赵广
Thesis Advisor朱万泽
2015
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Name硕士
Degree Discipline自然地理学
Keyword峨眉冷杉 树干呼吸 时空动态 影响因子
Abstract树干是森林木质组织的重要组成部分,也是森林生态系统中最大的生物量储存体,在全球范围内是巨大的碳库。树干呼吸占到树木自养呼吸的14~48%,是森林碳循环的重要组成部分。因此,阐明树干呼吸的时空变化规律及其与影响因子的关系,准确评估树干呼吸在森林碳循环中的作用,不仅可为构建陆地生态系统碳循环模型提供基础数据,而且对于研究全球变化下森林生态系统的响应和适应有重要科学意义。鉴于西南林区在我国森林碳增汇功能中的重要地位,本文以贡嘎山东坡峨眉冷杉(Abies fabri)为研究对象,采用红外线气体分析仪-土壤呼吸气室水平测定法于2014年5~12月原位监测了峨眉冷杉中龄林和成熟林树干呼吸速率,测定、比较了不同林龄、径阶峨眉冷杉树干呼吸的时间动态,探索了树干呼吸的空间变化规律,估算林分树干呼吸总量,并分析峨眉冷杉树干呼吸速率与林木相关生物因素和环境因子的关系。本文主要研究结果如下: (1)峨眉冷杉树干呼吸时间变化格局:树干呼吸日变化呈单峰型,高峰值主要出现在12:00~16:00之间,最小值发生在6:00附近。中龄林和成熟林树干呼吸季节变化趋势相似,均呈单峰模式,但成熟林树干呼吸速率显著高于中龄林。树干呼吸速率从5月份开始升高,7月份中龄林和成熟林呼吸值均达到最高,分别为1.69和2.76 μmol?m-2?s-1;之后,呼吸速率下降明显,最低值出现在12月,分别为 0.01和0.15μmol?m-2?s-1。测定期间,5~10月为峨眉冷杉生长季,平均呼吸速率为1.45 μmol?m-2?s-1, 11~12月为非生长季,平均呼吸值为0.25 μmol?m-2?s-1。 (2)峨眉冷杉树干呼吸空间变化格局:不同高度的树干温度表现为T0.3 m>T1.3 m>T2.3 m,树干1.3 m处的呼吸速率最大。整体上,随着季节的变化,不同树干高度呼吸速率间的差异逐渐减小。不同方向树干温度和呼吸速率均表现为南面>北面。 (3)峨眉冷杉树干呼吸与环境因子的关系:树干呼吸与气温、土温和树干温度的指数关系均达到显著水平,气温、土温和树干温度分别可以解释树干呼吸变化的76%~92.7%、58 %~97%和65.5%~96.5%。小胸径的树干呼吸与气温的相关性高于土温和树干温度,而大胸径的树干呼吸与树温和土温的相关性较高。树干呼吸气温敏感系数Q10在2.7~6.6之间变化,中龄林树干呼吸平均Q10为4.4,成熟林树干呼吸平均Q10为3.6。树干表面相对空气湿度日变化和季节变化明显;胸径10~75 cm的树干呼吸与相对湿度的指数关系达到显著水平,胸径80~90 cm 未达到显著水平。 (4)峨眉冷杉树干呼吸与生物因子的关系:随胸径增大,树干呼吸速率先迅速升高,后趋于平缓;中龄林Q10随树干DBH增大而升高,成熟林Q10随DBH增大而减小。中龄林树干边材平均氮素含量为1.41 g/kg,高于成熟林平均含量(1.38 g/kg);树干呼吸值与边材氮素存在显著正相关关系,且中龄林树干呼吸与氮素的相关性高于成熟林。树干生长速率变化范围在1.27 ~3.62 mm/a之间,随树干胸径增大,树干生长速率先增大后减小;树干呼吸值与树干生长速率的正相关关系达到显著水平。 (5)峨眉冷杉树干呼吸的表达方式与呼吸通量估算:不同表达单位的树干呼吸与各种生物因子的相关程度不同。边材氮含量与五种表达方式的树干呼吸速率的相关性均达到显著水平;基于树干表面积和树干体积的呼吸速率受胸径影响最大,基于边材干重和氮素含量的树干呼吸速率与氮素含量、生长速率和边材含水率相关性达到显著水平,且与生长速率的关系最为密切。整体上,边材含水率与呼吸速率的相关性较低。表面积法推算的中龄林树干CO2年释放通量为8.51 t CO2? hm-1?a-1,成熟林为 16.65 t? CO2?hm-1?a-1;积分法推算的中龄林树干CO2年释放通量为19.19 t? CO2?hm-1?a-1,成熟林为27.46 t? CO2?hm-1?a-1;两种方式估算的林分树干呼吸CO2年释放通量差异较大;积分法更适合估算贡嘎山地区峨眉冷杉中龄林和成熟林的树干呼吸通量。
Other AbstractStem, an important part of forest xylem tissue, is not only the biggest biomass storage in forest ecosystems, but also a huge carbon pool on a global scale. Stem respiration, accounting for about 14~48% of tree autotrophic respiration, plays a pivotal role in forest ecosystem carbon. Investigation temporal-spatial variations and the controlling factors of stem respiration, and accurate assessment the role of stem respiration, are not only essential steps in providing basic data for constructing carbon cycling models of terrestrial ecosystem, but also have great scientific significance for studying the response and adaptation of forest ecosystem to global change .Southwest forestry area occupies an important position in forest sinks of China. In this paper, we measured stem respiration in situ for immature and mature Abies fabri forests on Gongga Mountain using IRGA with Li-6400-09 during period from May to December 2014. A technique of horizontally oriented soil chamber (HOSC) was applied to measure the CO2 released by stems. Our objectives were to examine the temporal-spatial variations in stem respiration of Abies fabri and to determine the relationship between stem respiration and environment and biotic factors. The main results of the research are as follows: (1) The temporal variations in stem respiration of Abies fabri The diurnal course of stem respiration presented a clear single-peak type, of which high peak mainly occurred between12:00 to 16:00 and the minimum appeared at 6:00. The seasonal variation in stem respiration of immature and mature Abies fabri forests showed similar pattern, with their maximum occurring in July and minimum occurring in December. While the respiration in mature forests were significantly higher than immature forests, with the rate of 1.69 and 2.76 μmol?m-2?s-1 in July respectively , and 0.01and 0.15μmol?m-2?s-1 in December respectively. The means stem respiration of growing season (from May to October) and non-growing season (from November to December) were 1.45 and 0.25 μmol CO2?m-2?s-1 respectively (2) The spatial variations in stem respiration of Abies fabri Stem temperature at different height ranked as 0.3 m>1.3 m>2.3 m, but maximum stem respiration appeared at 1.3 m. On the whole, with the season changing,the gap of stem respiration in different height tended to be closed. Both respiration and temperature on the south face of stem were stronger than the north. (3) The relationship between stem respiration and environment factors Strong exponential relationship had been developed between stem respiration and temperature (air, soil and stem temperature). Air temperature, soil temperature and stem temperature could explain the variation in stem respiration for about 76~92.7%, 58~97% and 65.5%~96.5% respectively. The correlation between stem respiration of small diameter and air temperature were more significant than that of the soil temperature and stem temperature, while stem respiration of large diameter had a strong relationship with stem temperature and soil temperature. Q10, sensitivity coefficient of respiration and air temperature, ranged from 2.7 to 6.6, with 4.4 for average in immature forest and 3.6 for average in mature forest. Relative air humidity in stem surface showed strong diurnal and seasonal patterns. The exponential relationship between relative air humidity and stem respiration with DBH from 10~75 cm reached significant level, but the stem respiration with DBH from 80~90 cm had not. (4) The relationship between stem respiration and biotic factors. With increasing diameter, stem respiration of Abies fabri were rising at first and then remained unchanged. The Q10 in immature forest increased, but it decreased in mature forest, with the increase of diameters scale of tress. Average nitrogen content in sapwood of immature forest was 1.41g/kg, which was higher than that of mature forest. The relationship between stem respiration and nitrogen content in sapwood was a significant positive correlation, and the correlation with immature forest was higher than that with mature forest. With increasing diameter, stem growth rate increased at first and then decreased, ranging from 1.27 to 3.62 mm/a. The positive correlation between stem respiration and growth rate reached significant level. (5) The expressing units and efflux of stem respiration Different expressing units of stem respiration are correlated with various biotic factors to different degrees. Five expressing units of stem respiration were strongly correlated with nitrogen contents in sapwood. Respiration rates per unit stem surface and volume were strongly affected by DBH, while respiration rates per unit sapwood dry mass and nitrogen content were significantly correlated with stem growth rate, nitrogen content and moisture content in sapwood. On the whole, there was a poor relationship between moisture content in sapwood and respiration rates. Two methods were applied to estimate respiration flux of Abies fabri. Annual efflux of CO2 from stems for immature and mature forests were 8.51 and 16.65 t? CO2?hm-1?a-1 respectively, estimating on the base of stem surface areas. And when estimating on the base of stem volume, they were 19.19 and 27.46 t? CO2?hm-1?a-1 respectively. There were big gaps between annual efflux CO2 estimated by two methods from stems of Abies fabri.
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/13959
Collection山地表生过程与生态调控重点实验室
Recommended Citation
GB/T 7714
赵广. 贡嘎山峨眉冷杉树干呼吸时空动态及其影响因子[D]. 北京. 中国科学院大学,2015.
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