【作者】 雷丕锋；

【导师】 项文化； 田大伦；

【作者基本信息】 中南林学院 ， 生态学， 2004， 硕士

【摘要】 碳素营养不仅是绿色植物的重要组成部分，也是最活跃的环境因素，随着全球气候变化研究的深入，森林土壤碳因其巨大的库存量而受到关注。杉木是我国南方亚热带地区特有的优良速生乡土用材树种，目前，我国杉木林面积1239.1×10⁴ hm²，蓄积量为47357.33×10⁴ m³，分别占全国人工林面积和蓄积量的26.55％和46.89％，杉木人工林成为南方集体林区的主要森林类型之一，在区域碳平衡中发挥着重大的作用。本研究以杉木人工林土壤有机碳贮量及其形成的生态过程为主要研究内容，对杉木人工林的土壤有机碳贮量、凋落物及其分解以及土壤呼吸进行测定，来探索杉木人工林土壤有机碳贮量形成与碳平衡机理。主要研究结果为： 杉木人工林土壤层（0～75cm）的有机碳贮量为126.168 t hm^-2，高于同一林区的马尾松林和次生阔叶林地的土壤有机碳贮量，其大小顺序为：杉木林＞马尾松林＞次生阔叶林。不同林分的土壤碳贮量均随着土层深度的增加而减小，主要集中在土壤表层和亚表土层，杉木人工林、马尾松林和次生阔叶林的土壤表层有机碳贮量分别占相应林分土壤有机碳总贮量的53.62％、60.02％和64.35％。 会同14～16年生的杉木人工林内，平均每年的凋落物量为1201.24 kg hm^-2·a^-1，主要由针叶、小枝、落果和其他碎屑物质组成的，其中针叶的年凋落物量最大，为838.92 kg hm^-2·a^-1，占年凋落物总量的69.84％。杉木人工林通过凋落物碳的年总归还量为557.06 kg hm^-2·a^-1，杉木林各年通过凋落物归还的碳总量随着林分年龄的增长而增加。在凋落物各组分归还的碳总量中，主要通过针叶和枯枝凋落，它们凋落的年平均碳总量占年总凋落物碳量的94.4％。杉木人工林年凋落物各组分中的碳含量存在一定的差异，按凋落物各组分中碳含量的高低顺序排列为：针叶＞落果＞碎屑＞枯枝。杉木人工林年凋落物各组分在分解过程中碳的总释放量约为158.06 kg hm^-2·a^-1，占年凋落物碳总量的28.25％，其中的一部分以CO₂的形式释放到大气环境中，另一部分以腐殖质的形式进入土壤并储存于士壤中，成为土壤有机碳的重要来源，再进一步通过土壤呼吸和有机质的氧化分解释放到大气环境中。在加N和加林下植被叶的凋落物分解实验中，3种不同的处理方式对杉木林凋落物针叶的分解均有不同程度的促进作用，其干重损失率为29.13％～43.67％，其中以加入林下植被叶对杉木针叶凋落物的分解促进作用最大。 会同杉木人工林土壤呼吸的日变化规律为，在7月份，土壤呼吸速率日变化曲线呈双峰型，在8时和16时达到极大值，分别为1.317和1.357 μmol m^-2·s^-1，全天平均土壤呼吸速率为1.174μmol m^-2·s^-1。在10月份，土壤呼吸速率曲线呈单峰型，最大值出现在午后14时，为0.984μmol m^-2·s^-1，硕士学位论文:中文摘要但全天土壤呼吸速率的变化不大，为0.746一0.984卿olm-;护。12月份的土壤呼吸速率很小，全天平均土壤呼吸速率仅为0.271脚olm-子s-l，其土壤呼吸曲线也是呈单峰型，在18时达到全天土壤呼吸速率最大值，为0.313卿01 m-4s-l。会同杉木人一工林土壤呼吸速率的季节变化为，随着时间的推移，7月到12月土壤呼吸速率逐步降低，土壤平均呼吸速率为0.271一1.174娜olm一弓扩。经过估算，会同杉木人工林土壤呼吸过程中co:的年释放量为10.474thm’寻r，折合成碳，则每年林地土壤释放的碳总量为2.8565 thm母a-，。更多还原

【Abstract】 Carbon element is not only the important component of the plant, but also one of the most active environmental factors. As the researches on the global warming advanced, the forestland soil carbon attracts great attention for its huge storage. Chinese fir (Cunninghanaa lannceolata) is a fast-growing native Chinese species with valuable timber attributes in subtropical area of southern China. The statistics form the 5th National Forest Researches Inventory showed that the total area and stocking volume of Chinese fir plantations have reached 12.39 million ha and 473.57 million m3, respectively, accounting for 26.55% and 46.89% of those of plantation in the whole nation. Chinese fir plantation has become one of the main forests in southern area, and played a role on the carbon balance of terrestrial ecosystem. To figure out the forming procedure of soil carbon storage and its balance in Chinese fir plantation, the soil organic carbon storage, litterfall amount and its decomposition, and soil respiration were studied in this dissertation. The main results of the research are as follows.The soil carbon storage in Chinese fir plantation was 126.168 t hm"2 at the depth between 0 and 75cm. In contrast to the massoniana pine forestland and the second broadleaf forestland, the carbon storage order ranked as follow: Chinese fir forestland>Massoniana Pine forestland>the second broadleaf forestlands, and they followed the same laws: soil carbon storage of different forestlands decreased as the depth of soil increased. The soil carbon storage mainly distributed in the soil surface layer (0~30cm), accounting for 53.62%, 60.02% and 64.33% of the total soil carbon storage in Chinese fir forestland, Massoniana Pine forestland and the second broadleaf forestlands, respectively.The mean annual amount of dry litter was 1201.24 kg hm-2 a-1 in Chinese fir plantation, consisting of needle leaf, fallen twig, fallen fruit and other detritus, of which the needle leaf was the largest component, the amount was 838.92 kg hm-2 a-1 and made up 69.84%. The return carbon amount through litter in Chinese fir plantation was 557.06 kg hm-2 a-1, and increased with the growth of the Chinese fir plantation. The carbon storage in litter mainly focused on the needle leaf and fallen twigs, which accounted for 94.4%. The carbon concentration of the litter varied with the components of litter-fall, the order was as follow: needle leaf > fallen fruit > other detritus > fallen twig. The annual carbon release was 158.06 kg hm-2 a-1 in the course of the litter decomposition, making up 28.25% of the carbon amount in litter. Some of themreturned to the atmosphere as CO2, and the other stored as the humus in the soil, which was one of the sources of the soil carbon. The three kinds of treatment to the needle leaf was positive to the decomposition in the experiments of the litter decomposition, the dry weight release percentage ranged from 29.13% to 43.67%, among them the understorey leaf’s contribution to the decomposition of needle leaf was most great.The daily changes of soil respiration was as follows: in July, the mean soil respiration rate was 1.174 umol m-2 s-1, and the soil respiration curve over the time was two peaks, occurring at 8:00 and 16:00, which was 1.317 and 1.357, respectively; in October, the soil respiration curve over the time was single peak, occurring at 8:00 and 16:00, which was 0.984, and it changed little, ranging from 0.746 to 0.984; in December, the mean soil respiration rate was only 0.271 umol m-2 s-1, and the soil respiration curve over the time was single peak, the soil respiration reached the highest point at 18:00, which was 0.313. The soil respiration rate over season changes decreased from July to December, the mean soil respiration ranged from 0.271 to 1.174. The annual soil CO2 release amount was 10.474 t hm-2 a-1, and 2.8565 t hm-2 a-1 when it was transformed to carbon.更多还原