Schaefer C E G R, do Amaral E F, de Mendonça B A F, Oliveira H, Lani J L, Costa L M, Fernandes Filho E I
Departamento de Solos, Universidade Federal de Viçosa, 36571-000 Viçosa, Minas Gerais, Brazil.
Environ Monit Assess. 2008 May;140(1-3):279-89. doi: 10.1007/s10661-007-9866-0. Epub 2007 Sep 11.
The relationships between soils attributes, soil carbon stocks and vegetation carbon stocks are poorly know in Amazonia, even at regional scale. In this paper, we used the large and reliable soil database from Western Amazonia obtained from the RADAMBRASIL project and recent estimates of vegetation biomass to investigate some environmental relationships, quantifying C stocks of intact ecosystem in Western Amazonia. The results allowed separating the western Amazonia into 6 sectors, called pedo-zones: Roraima, Rio Negro Basin, Tertiary Plateaux of the Amazon, Javari-Juruá-Purus lowland, Acre Basin and Rondonia uplands. The highest C stock for the whole soil is observed in the Acre and in the Rio Negro sectors. In the former, this is due to the high nutrient status and high clay activity, whereas in the latter, it is attributed to a downward carbon movement attributed to widespread podzolization and arenization, forming spodic horizons. The youthful nature of shallow soils of the Javari-Juruá-Purus lowlands, associated with high Al, results in a high phytomass C/soil C ratio. A similar trend was observed for the shallow soils from the Roraima and Rondonia highlands. A consistent east-west decline in biomass carbon in the Rio Negro Basin sector is associated with increasing rainfall and higher sand amounts. It is related to lesser C protection and greater C loss of sandy soils, subjected to active chemical leaching and widespread podzolization. Also, these soils possess lower cation exchangeable capacity and lower water retention capacity. Zones where deeply weathered Latosols dominate have a overall pattern of high C sequestration, and greater than the shallower soils from the upper Amazon, west of Madeira and Negro rivers. This was attributed to deeper incorporation of carbon in these clayey and highly pedo-bioturbated soils. The results highlight the urgent need for refining soil data at an appropriate scale for C stocks calculations purposes in Amazonia. There is a risk of misinterpreting C stocks in Amazonia when such great pedological variability is not taken into account.
即使在区域尺度上，亚马逊地区土壤属性、土壤碳储量和植被碳储量之间的关系也鲜为人知。在本文中，我们使用了来自RADAMBRASIL项目的西部亚马逊地区大型可靠土壤数据库以及近期植被生物量估算数据，来研究一些环境关系，量化西部亚马逊地区完整生态系统的碳储量。研究结果将西部亚马逊地区划分为6个区域，即土壤地带：罗赖马、黑河盆地、亚马逊第三纪高原、雅瓦里-茹鲁阿-普鲁斯低地、阿克里盆地和朗多尼亚高地。整个土壤的最高碳储量出现在阿克里和黑河区域。在前者，这是由于高养分状况和高黏土活性，而在后者，则归因于广泛的灰化作用和砂质化作用导致的碳向下移动，形成了灰化层。雅瓦里-茹鲁阿-普鲁斯低地浅薄土壤的年轻特性，加上高铝含量，导致植物生物量碳/土壤碳比值较高。罗赖马和朗多尼亚高地的浅薄土壤也观察到类似趋势。黑河盆地地区生物量碳从东到西持续下降，这与降雨量增加和砂含量升高有关。这与砂质土壤中碳保护较少和碳损失较大有关，因为砂质土壤遭受活跃的化学淋溶和广泛的灰化作用。此外，这些土壤的阳离子交换容量较低，保水能力也较低。以深度风化的红壤为主的区域总体上具有高碳固存模式，且高于马德拉河和内格罗河以西亚马逊上游地区的浅薄土壤。这归因于碳在这些黏土性且高度土壤生物扰动的土壤中更深的掺入。研究结果凸显了为在亚马逊地区进行碳储量计算而在适当尺度上完善土壤数据的迫切需求。如果不考虑如此巨大的土壤学变异性，就存在误读亚马逊地区碳储量的风险。
