School of Forestry, Northern Arizona University, Flagstaff, AZ 86011, USA.
The Evergreen State College, Olympia, WA 98505, USA.
New Phytol. 2012 Aug;195(3):631-639. doi: 10.1111/j.1469-8137.2012.04185.x. Epub 2012 May 29.
Soil carbon dioxide (CO(2)) efflux is a major component of terrestrial carbon (C) cycles; yet, the demonstration of covariation between overstory tree genetic-based traits and soil C flux remains a major frontier in understanding biological controls over soil C. Here, we used a common garden with two native tree species, Populus fremontii and P. angustifolia, and their naturally occurring hybrids to test the predictability of belowground C fluxes on the basis of taxonomic identity and genetic marker composition of replicated clones of individual genotypes. Three patterns emerged: soil CO(2) efflux and ratios of belowground flux to aboveground productivity differ by as much as 50-150% as a result of differences in clone identity and cross type; on the basis of Mantel tests of molecular marker matrices, we found that c. 30% of this variation was genetically based, in which genetically similar trees support more similar soil CO(2) efflux under their canopies than do genetically dissimilar trees; and the patterns detected in an experimental garden match observations in the wild, and seem to be unrelated to measured abiotic factors. Our findings suggest that the genetic makeup of the plants growing on soil has a significant influence on the release of C from soils to the atmosphere.
土壤二氧化碳（CO2）排放是陆地碳（C）循环的主要组成部分；然而，证明林冠树种遗传特征与土壤 C 通量之间的共变仍然是理解生物对土壤 C 控制的主要前沿。在这里，我们使用一个包含两个本地树种，黑杨（Populus fremontii）和山杨（P. angustifolia）及其天然杂交种的共同花园，以及其个体基因型的重复克隆的分类学身份和遗传标记组成，来测试地下 C 通量的可预测性。出现了三种模式：由于克隆身份和杂交类型的差异，土壤 CO2 排放和地下通量与地上生产力的比值差异高达 50-150%；基于分子标记矩阵的 Mantel 检验，我们发现这种变异中有 c. 30%是基于遗传的，在树冠下，遗传相似的树木支持比遗传不同的树木更相似的土壤 CO2 排放；在实验花园中检测到的模式与野外观察结果相匹配，并且似乎与测量的非生物因素无关。我们的研究结果表明，生长在土壤上的植物的基因组成对土壤向大气中释放 C 具有重要影响。
