|Alternative Title||Characteristics of Carbon Stock and its Spatial of Differentiation of the Ground Cover in Tibet|
|Place of Conferral||北京|
|Keyword||草本 凋落物 枯倒木 地被物 碳储量 西藏|
|Abstract||以大气CO2浓度增加和温度升高为主要特征的全球气候变化正在改变着陆地生态系统的结构、功能和过程。森林生态系统作为陆地生态系统的最大碳库，国内外很多学者开展了对森林生态系统碳储量的研究，在全国或者区域尺度森林生态系统碳储量研究中，集中对乔木、土壤两个层次的研究，而忽略了草本、凋落物和枯倒木生物量。由于西藏高原对气候变化敏感性，使其成为森林生态系统碳库对气候变化的响应的热点研究区域之一。但迄今为止，有关西藏高原林下地被物碳储量研究还未见报道。因此，本研究根据西藏清查资料的森林面积和蓄积量分布情况，在西藏林芝地区、昌都地区、日喀则地区、山南地区分层抽样，确定调查样点的个数和具体分布，采用样方法研究了不同龄级下或不同林分下草本、凋落物和枯倒木碳储量，以及地被物碳储量的空间差异性，研究结果如下： (1) 不同龄级下草本碳储量的研究结果显示：冷杉、高山松、云南松、圆柏和桦木林下草本碳储量随龄级的增大而增加；高山栎林下，草本碳储量随龄级的增大而减小。另外，草本碳储量最高是圆柏成熟林下草本碳储量，为1.32±0.33 t/hm2；草本碳储量最低在杨树幼龄林，为0.31±0.04 t/hm2。不同龄级下凋落物碳储量的研究结果为：在冷杉、云杉和圆柏林下，凋落物碳储量随龄级的增大而升高；相反，高山栎和桦木林下凋落物随着龄级增大而降低；在高山松幼龄林凋落物碳储量为0.87±0.17 t/hm2，中龄林下凋落物碳储量为3.92±1.66 t/hm2，成熟林凋落物碳储量为3.48±0.93 t/hm2；在云南松幼龄林林下凋落物碳储量为.69±0.09 t/hm2，中龄林为0.47±0.13 t/hm2，成熟林为0.53±0.19 t/hm2。不同龄级下枯倒木碳储量的研究结果为：冷杉、云杉、高山松、云南松林下枯倒木碳储量随龄级增大而增大。对于冷杉，幼龄林、中龄林和成熟林下枯倒木碳储量三者之间存在显著差异；对于云杉，成熟林与其他两个龄级下枯倒木碳储量存在显著差异；对于高山松，成熟林下与幼龄林下枯倒木碳储量差异显著。 (2) 不同森林类型林分下地被物碳储量差异较大。在幼龄林下软阔叶林草本和凋落物碳储量显著高于针叶林。在中龄林下，硬阔叶和软阔叶林下凋落物碳储量与暗针叶林差异显著，硬阔叶林与亮针叶林差异显著；枯倒木碳储量大小为：暗针叶林(2.50±0.52 t/hm2)和亮针叶林(2.24±0.45 t/hm2)显著高于硬阔叶(0.56±0.19 t/hm2)。在成熟林下，草本碳储量大小为：亮针叶林(0.83±0.16 t/hm2) >暗针叶林(0.73±0.12 t/hm2)>软阔叶(0.59±0.19 t/hm2)>硬阔叶(0.53±0.11 t/hm2)，且差异显著；凋落物碳储量为：硬阔叶(2.52±0.36 t/hm2)>暗针叶林(1.87±0.28 t/hm2)>亮针叶林(1.72±0.24 t/hm2)>软阔叶(0.89±0.19 t/hm2)，且差异显著；枯倒木碳储量为：暗针叶林(8.03±1.12 t/hm2)显著高于硬阔叶(2.32±0.37 t/hm2)和软阔叶(2.21±0.29 t/hm2)。 (3) 林下地被物碳储量的垂直分布特征为：草本、凋落物和枯倒随海拔的升高呈先增加后降低的趋势，其中，海拔范围在3400-3600 m内，草本、凋落物和枯倒木碳储量最大，草本碳储量为0.82 t/hm2，凋落物碳储量为3.13 t/hm2，枯倒木碳储量为10.92 t/hm2。林下地被物碳储量的坡度分布特征为：草本碳储量随着坡度的增加而缓慢增大，在坡度高于55°时，草本碳储量达到最大，为0.80 t/hm2；凋落物和枯倒木碳储量随着坡度的增加而增大，在坡度为15~25°时凋落物和枯倒木碳储量达到最大，分别为：2.10 t/hm2、5.75 t/hm2，之后，随着坡度的增加而减少。林下地被物碳储量坡向分布特征进行了研究，草本碳储量的结果为：半阳坡最高，为0.83 t/hm2；阳坡为0.82 t/hm2；阴坡为0.74 t/hm2；半阴坡最低，为0.71 t/hm2。凋落物碳储量：半阴坡显高于著阴坡、半阳坡和阳坡，阴坡显著高于半阳坡、阳坡。枯倒木：半阴坡显著高于阴坡、半阳坡和阳坡，阴坡显著高于阳坡。西藏主要森林类型林下地被物碳储量水平分布特征表现为：南高北低，藏东、西部低，而中部林芝地区最高，且差异显著。在低纬度27~28°，草本碳储量为1.27 t/hm2；凋落物碳储量为1.55 t/hm2；枯倒木碳储量为7.23 t/hm2。在高纬度31~32°之间，草本碳储量为0.74 t/hm2；凋落物碳储量为0.29 t/hm2；枯倒木碳储量为2.19 t/hm2。高纬度与低纬度的地被物碳储量存在显著差异。 (4) 地被物碳储量与年均气温和年降水量大小相关性高，西藏高原林下地被物碳储量先随年均气温和年降水量的增加而增加，当年均气温达到7—9°，地被物碳储量达到最大，为7.95 t/hm2；年降水量达到为700—800 mm，地被碳储量达到最大，为2.18 t/hm2，之后随年均气温和年降水量的增加而减少。|
|Other Abstract||Global climate change has been concerned about worldwide because climate change characterized by global warming and atmospheric CO2 enrichment is changing the structure and function of terrestrial ecosystem. As the major part of the Earth’s terrestrial ecosystems and largest terrestrial carbon pool, forest ecosystem plays an important role in carbon sink, pool, and source. Many scholars at home and abroad research the carbon storage of forest ecosystem. Despite an increasing number of studies have addressed carbon storage in the trees and soil, the herbaceous, litter and dead and drying tree in such storage remains poorly understood. Due to the great sensitivity to climate change sensitivity in Tibet, make it a hot climate change research area. As yet, far less information is available on the characteristics of carbon stock in the forest ecosystem at the regional level in Tibet. Therefore, based on forest area and volume of Tibet forest resource inventory, employed stratified sampling and quadrat method, this study estimated the carbon storage of the herb, litter and dead and drying tree, and its spatial differentiation at the Linzhi, Changdu, Rikaze, Shannan area. The main results are as follows.|
1. The results showed that the carbon storage of herb were no significant difference in different age classes. The carbon storage of the herb increased with the increases of stand age in the Abies, Pinus densata, Pinus yunnanensis, Sabina Chinensis(Linn.) Ant, Betulaceae; decreased with the increases of stand age in the Quercus semecarpifolia; was 0.75±0.37 t/hm2 in mature forest, was 0.68±0.21 t/hm2 in middle-aged forest, was 0.58±0.14 t/hm2 in young forest of the Picea asperata. The results showed that the carbon storage of litter were difference in different age classes. The carbon storage of the litter increased with the increases of stand age in the Abies, P. asperata, and Sabina Chinensis(Linn.) Ant forest, decreased with the increases of stand age in the Q. semecarpifolia, Betulaceae forest, irregular with stand age in the P. densata and P. yunnanensis forest. The results showed that the carbon storage of dead and drying tree were significant difference in different age classes. The carbon storage of the dead and drying tree increased with the increases of stand age in the Abies, P. asperata, P. densata and P. yunnanensis forest.
2. Carbon storage of the ground cover varied greatly with the forest stand. The carbon storage of the herb and litter was more soft broad-leaved forest than coniferous forest in the young forest. In middle-aged forest ecosystem, statistically significant effect was found on the litter carbon storage for broad-leaved forest and dark coniferous forest. The dead and drying tree carbon storage was more bright and dark coniferous forest (2.24±0.45 t/hm2, 2.50±0.52 t/hm2) than sclerophyllous broad-leaved forest (0.56±0.19 t/hm2). In mature forest ecosystem, the herb carbon storage stood in the order of bright coniferous forest(0.83±0.16 t/hm2)> dark coniferous forests (0.73±0.12 t/hm2)> soft broad-leaved forest(0.59±0.19 t/hm2)> sclerophyllous broad-leaved forest(0.53±0.11 t/hm2), and the difference was significant; the litter carbon storage stood in the order of sclerophyllous broad-leaved forest(2.52±0.36 t/hm2)> dark coniferous forest(1.87±0.28 t/hm2)> bright coniferous forest(1.72±0.24 t/hm2)> soft broad-leaved forest(0.89±0.19 t/hm2), and the difference was significant; the carbon storage of dead and drying tree were significantly different with each other.
3. The carbon storage of ground cover increased with altitude ranged from 2000 to 3600 mm, while slightly declined with altitude ranged from 3600 to 4200 mm. Among, the maximum carbon storage of herb, litter, dead and drying tree were 0.82 t/hm2, 3.13 t/hm2, 10.92 t/hm2 at altitudes between 3400 and 3600 m, respectively. The carbon storage of ground cover was difference in different slope. The carbon storage of herb increased with the increases of slope, with the maximum (0.80 t/hm2) at the slope of 55°. But, the carbon storage of litter and dead and drying tree increased with the increases of slope (0-25°), and decreased with the increases of slope (>25°), with the maximum (2.10 t/hm2, 5.75 t/hm2) at slope between 15° and 25°. Comparison with the carbon storage in different exposure, the carbon storage of the herb was 0.83 t/hm2 at semi-sunny slope, 0.82 t/hm2 at cloudy slope, 0.74 t/hm2 at sunny slope, 0.71 t/hm2 at semi-cloudy slope. The order of carbon storage of litter and dead and drying tree from large to small was semi-cloudy slope>cloudy slope>semi-sunny slope>sunny slope, the differences among four exposure were striking. The level distribution characteristics of ground cover carbon storage performance: the south were significantly higher than the north, the central were significantly higher than the eastern and western. At low latitudes from 27 to 28°, the carbon storage of herb was 1.27 t/hm2; which of the litter and dead and drying tree were 1.55 t/hm2, 7.23 t/hm2respectively. Between the high latitudes from 31 to 32°, the carbon storage od the herb was 0.74 t/hm2; which of the litter and dead and drying tree were 0.29 t/hm2, 2.19 t/hm2 respectively.
4. The correlation analysis of annual precipitation and mean annual temperature show that ground cover carbon storage will increase with the increase of precipitation ranged from 200 mm to 800 mm, and temperature ranged from 0° to 9°, slightly decline with the increase of precipitation(>800 mm) and temperature(>9°).
|杨阳. 西藏高原主要森林类型下地被物碳储量及空间变异性研究[D]. 北京. 中国科学院研究生院,2013.|
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