Effect of shrub coverage on grassland ecosystem carbon pool in southwestern China
XUE Jing-Yue, WANG Li-Hua, XIE Yu, GAO Jing, HE Jun-Dong, WU Yan
Chin J Plant Ecol
2019, 43 ( 4):
365-373.
DOI: 10.17521/cjpe.2017.0062
AimsThe grassland in southwestern China is mainly warm and tropical grass and shrub grassland, accounting for approximately one-tenth of the national grassland area. Analysis of the relationship between shrub coverage and the grassland carbon pool and its composition is of great significance for accurately assessing carbon storage in the southwestern grassland, which grassland is still in the secondary succession stage. MethodsIn a field investigation, 41 representative plots of different geomorphic types in southwestern China were divided into three types according to shrub coverage: no shrub grassland community (shrub coverage is 0), low shrub coverage grassland community (shrub coverage is 0-10%) and high shrub coverage grassland community (shrub coverage is 10%-30%). Carbon density was calculated by measuring the aboveground and underground biomass and litter biomass of grassland communities at different shrub coverage levels, as well as plant and soil carbon content. Important findings The results showed that with increasing shrub coverage and species richness in grasslands, the ecosystem vegetation carbon density increased from 0.304 kg·m -2 to 1.574 kg·m -2, and the roots and litter carbon density also showed growth trends. The soil carbon density increased from 7.215 kg·m -2 to 9.735 kg·m -2, and the ecosystem carbon density increased from 7.519 kg·m -2 to 11.309 kg·m -2, with increasing shrub coverage. Regarding the composition of the grassland carbon pool, the soil carbon pool of the low shrub coverage grassland accounted for the smallest proportion of the ecosystem carbon pool. In summary, the increase in shrub coverage changes the composition of the grassland ecosystem carbon pool and leads to an increase in the amount of ecosystem carbon. Therefore, when estimating the grassland ecosystem carbon pool, it is necessary to overall plan for and take into account the changes in grassland shrub coverage in southern China.
地点 Place | 样地数 No. of sites | 经度 Longitude (E) | 纬度 Latitude (N) | 海拔 Altitude (m) | 地貌类型 Landform | 样地编号 Site number | 四川达州 Dazhou, Sichuan | 2 | 107.60°-108.18° | 31.86°-32.17° | 1 055-1 060 | 盆周山地 Mountain area of basin | 7, 14 | 四川绵阳 Mianyang, Sichuan | 1 | 102.09° | 26.93° | 1 296 | 紫色丘陵区 Purple hilly area | 8 | 四川雅安 Ya’an, Sichuan | 3 | 102.49°-102.87° | 29.29°-29.61° | 1 171-1 592 | 盆周山地 Mountain area of basin | 10, 15, 37 | 四川凉山 Liangshan, Sichuan | 15 | 102.03°-103.77° | 26.26°-29.08° | 1 042-1 998 | 干热河谷及中山区 Dry-hot valley and Middle mountain | 2, 4, 5, 6, 13, 19, 20, 21, 23, 24, 31, 32, 36, 39, 41 | 四川攀枝花 Panzhihua, Sichuan | 5 | 101.73°-101.85° | 26.42°-26.82° | 1 044-1 398 | 干热河谷 Dry-hot valley | 1, 3, 9, 17, 18 | 云南曲靖 Qujing, Yunnan | 3 | 103.47°-104.27° | 24.83°-26.77° | 1 669-1 948 | 滇中丘陵区 Central Yunnan hilly area | 33, 34, 35 | 云南红河 Honghe, Yunnan | 1 | 103.74° | 24.36° | 1 851 | 干热河谷 Dry-hot valley | 25 | 云南昆明 Kunming, Yunnan | 1 | 102.41° | 26.27° | 1 184 | 滇中丘陵区 Central Yunnan hilly area | 11 | 重庆 Chongqing | 8 | 108.71°-109.14° | 30.58°-32.06° | 1 201-1 886 | 盆周山地 Mountain area of basin | 16, 26, 27, 28, 29, 30, 38, 40 | 贵州黔南 Qiannan, Guizhou | 2 | 105.08°-106.84° | 25.28°-26.34° | 1 469-1 504 | 喀斯特石漠化山区 Karst rocky desertification mountain area | 12, 22 |
Table 1
General information on the location and characteristics of the different investigation sites of grassland in southwestern China
Extracts from the Article
分别在我国西南地区的四川、重庆、云南、贵州等地选择丘陵地区、盆周山地、干热河谷地区、喀斯特石漠化区等典型地貌类型单元布置41个草地调查样地, 基本覆盖了我国西南地区的暖性草丛、暖性灌草丛、热性灌草丛、干热河谷灌丛等主要草地类型, 各样地的地理位置和基本信息见表1。
不同灌木植物盖度草地群落的植被碳库差异显著(F = 11.459, p < 0.001), 随着草地群落灌木植物盖度逐渐增大, 植被碳库逐渐增加, 且低灌木植物盖度草地群落和高灌木植物盖度草地群落的植被碳库显著大于无灌木植物草地群落, 但低灌木植物盖度草地群落和高灌木植物盖度草地群落的植被碳库差异不显著(表3; 图1)。就地上植物碳密度而言, 无灌木植物草地群落、低灌木植物盖度草地群落和高灌木植物盖度草地群落分别为0.057、0.089和0.073 kg·m-2, 彼此之间地上植物碳库差异显著(F = 3.348, p = 0.046)。其次, 凋落物碳密度分别为0.005、0.014和0.015 kg·m-2, 三者间凋落物碳库差异显著(F = 9.223, p = 0.001), 低灌木植物盖度草地群落和高灌木植物盖度草地群落的凋落物碳库显著大于无灌木植物草地群落。另外, 三者的地下植物碳密度分别为0.242、1.304和1.486 kg·m-2, 彼此之间差异显著(F = 10.969, p < 0.001), 表现为低灌木植物盖度草地群落和高灌木植物盖度草地群落的根系碳库显著大于无灌木植物草地群落(图1)。随着草地群落灌木植物盖度增加, 包括凋落物和地下碳库在内, 植被碳库有逐渐增加的趋势, 但这种变化随着灌木植物盖度增加, 趋势有所减弱, 表现为低灌木植物盖度草地群落和高灌木植物盖度草地群落的植被碳库差异不显著。
Other Images/Table from this Article
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Table 2
Grassland types and main species in grassland with different shrub coverage levels in southwestern China
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Table 3
Carbon pool in grassland ecosystem with different shrub coverage in southwestern China
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Fig. 1
Vegetation carbon pool of vegetation in grassland community with different shrub coverage in southwestern China. I, II, and III are the three different shrub coverage levels of the grassland community. I, II, and III represent no shrub grassland, low shrub coverage grassland, and high shrub coverage grassland, respectively. The data are the mean ± SE (I, II, n = 18; III, n = 5). Different lowercase letters indicate significant differences among sites with different shrub coverage of grassland levels (p < 0.05).
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Fig. 2
Soil carbon pool in grassland community with different shrub coverage in southwestern China. I, II, and III represent no shrub grassland, low shrub coverage grassland, and high shrub coverage grassland, respectively. The data are the means ± SE (I, II, n = 18; III, n = 5). Different uppercase letters indicate that the soil carbon pool at 0-100 cm was significantly different among different shrub coverage grassland communities (p < 0.05), and different lowercase letters indicate significant differences in the carbon pool at different soil layers (p < 0.05).
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