Biomass, carbon, and nitrogen pools in Mexican tropical dry forest landscapes
Biomass, carbon, and nitrogen pools in Mexican tropical dry forest landscapes
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DOI：
10.1007/s10021-002-0195-4
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发表时间：
2003-11-01
期刊：
影响因子：
3.7
通讯作者：
Ellingson, LJ
中科院分区：
文献类型：
--
作者：
Jaramillo, VJ;Kauffman, JB;Ellingson, LJ
热带干旱森林是热带地区分布最广的土地覆盖类型。随着世界范围内从森林到牧场或农业的土地利用/土地覆盖变化速度加快，量化完整森林和转换地点的生态系统生物量和碳（C）和氮（N）库变得越来越重要。在墨西哥中部沿海地区，我们采样总地上生物量（TAGB），和两个洪泛平原森林，三个高地干林，和四个牧场从干林转换的N和C池。我们还采样地下生物量和土壤C和N池在两个网站的每一个土地覆盖类型。洪泛平原森林的TAGB高达416 Mg ha（-1），而干旱森林的TAGB范围为94至126 Mg ha（-1）。来自干旱森林的牧场的TAGB范围从20至34毫克公顷。枯木（立木和倒木）占干旱森林总生物量的27%-29%，而洪泛区森林仅占10%左右。根生物量在洪泛平原森林中平均为32.0 Mg ha（-1），在干旱森林中平均为17.1 Mg ha（-1），在牧场中平均为5.8 Mg ha（-1）。虽然总的根生物量是相似的土地覆盖类型内的网站之间，根分布不同的深度和大小类。根系生物量的最高比例发生在土壤的顶部20厘米在所有网站。牧草地上和根系总碳库分别为12和2.2 Mg ha（-1），洪泛平原森林分别为180和12.9 Mg ha（-1）。草地的地上和根池分别为149和47 kg ha-1，洪泛平原森林的地上和根池分别为2623和264 kg ha-1。土壤有机碳库在牧场比在干旱森林，但土壤氮库计算相同的土壤深度时相似。生态系统碳库总数为306个。洪泛平原森林的Mg ha（-1），干旱森林的141 Mg ha（-1）和牧场的124 Mg ha（-1）。土壤C占整个生态系统C的37%~ 90%，土壤N占85%~ 98%。氮库缺乏一致的土地利用变化引起的土壤库减少表明，C和N的损失是由于燃烧的地上生物量。我们估计，在墨西哥，干燥的森林景观储存约2.3 Pg C，这大约等于该国万年青森林储存的C（约2.4 Pg C）。在墨西哥干燥的热带地区燃烧生物质向大气中的潜在碳排放量可能达到708 Tg C，而万年青森林为569 Tg C。
Tropical dry forest is the most widely distributed land-cover type in the tropics. As the rate of land - use/land-cover change from forest to pasture or agriculture accelerates worldwide, it is becoming increasingly important to quantify the ecosystem biomass and carbon (C) and nitrogen (N) pools of both intact forests and converted sites. In the central coastal region of Mexico, we sampled total aboveground biomass (TAGB), and the N and C pools of two floodplain forests, three upland dry forests, and four pastures converted from dry forest. We also sampled belowground biomass and soil C and N pools in two sites of each land-cover type. The TAGB of floodplain forests was as high as 416 Mg ha(-1), whereas the TAGB of the dry forest ranged from 94 to 126 Mg ha(-1). The TAGB of pastures derived from dry forest ranged from 20 to 34 Mg ha-1. Dead wood (standing and downed combined) comprised 27%-29% of the TABG of dry forest but only about 10% in floodplain forest. Root biomass averaged 32.0 Mg ha(-1) in floodplain forest, 17.1 Mg ha-1 in dry forest, and 5.8 Mg ha(-1) in pasture. Although total root biomass was similar between sites within land-cover types, root distribution varied by depth and by size class. The highest proportion of root biomass occurred in the top 20 cm of soil in all sites. Total aboveground and root C pools, respectively, were 12 and 2.2 Mg ha(-1) in pasture and reached 180 and 12.9 Mg ha(-1) in floodplain forest. Total aboveground and root pools, respectively, were 149 and 47 kg ha-1 in pasture and reached 2623 and 264 kg ha(-1) in floodplain forest. Soil organic C pools were greater in pastures than in dry forest, but soil N pools were similar when calculated for the same soil depths. Total ecosystem C pools were 306. The Mg ha(-1) in floodplain forest, 141 Mg ha(-1) in dry forest, and 124 Mg ha(-1) in pasture. Soil C comprised 37%-90% of the total ecosystem C, whereas soil N comprised 85%-98% of the total. The N pools lack of a consistent decrease in soil pools caused by land-use change suggests that C and N losses result from the burning of aboveground biomass. We estimate that in Mexico, dry forest landscapes store approximately 2.3 Pg C, which is about equal to the C stored by the evergreen forests of that country (approximately 2.4 Pg C). Potential C emissions to the atmosphere from the burning of biomass in the dry tropical landscapes of Mexico may amount to 708 Tg C, as compared with 569 Tg C from evergreen forests.