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Large contribution of recent photosynthate to soil respiration in tropical dipterocarp forest revealed by girdling
Journal of Ecology ( IF 5.3 ) Pub Date : 2021-10-31 , DOI: 10.1111/1365-2745.13806 Andrew T. Nottingham 1, 2 , Alexander W. Cheesman 3, 4 , Terhi Riutta 5, 6 , Christopher E. Doughty 7 , Elizabeth Telford 2 , Walter Huaraca Huasco 5 , Martin Svátek 8 , Jakub Kvasnica 8 , Noreen Majalap 9 , Yadvinder Malhi 5 , Patrick Meir 2, 10 , Yit Arn Teh 11
中文翻译：
环剥揭示热带龙脑香林近期光合产物对土壤呼吸的巨大贡献
更新日期：2021-10-31
Journal of Ecology ( IF 5.3 ) Pub Date : 2021-10-31 , DOI: 10.1111/1365-2745.13806 Andrew T. Nottingham 1, 2 , Alexander W. Cheesman 3, 4 , Terhi Riutta 5, 6 , Christopher E. Doughty 7 , Elizabeth Telford 2 , Walter Huaraca Huasco 5 , Martin Svátek 8 , Jakub Kvasnica 8 , Noreen Majalap 9 , Yadvinder Malhi 5 , Patrick Meir 2, 10 , Yit Arn Teh 11
Affiliation
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- Tropical forests are the most productive terrestrial ecosystems, fixing over 40 Pg of carbon from the atmosphere each year. A substantial portion of this carbon is allocated below-ground to roots and root-associated micro-organisms. However, there have been very few empirical studies on the dynamics of this below ground transfer, especially in tropical forests where carbon allocation processes are influenced by high plant species diversity.
- We used a whole-stand girdling experiment to halt the below-ground transfer of recent photosynthates in a lowland tropical forest in Borneo. By girdling 209 large trees in a 0.48 ha plot, we determined: (a) the contribution of recent photosynthate to root-rhizosphere respiration and; (b) the relationships among the disruption of this below-ground carbon supply, tree species composition and mortality.
- Mortality of the 209 trees was 62% after 370 days, with large variation among species and particularly high mortality within the Dipterocarpaceae (99%) and Fagaceae (100%) families. We also observed a higher risk of mortality following girdling for species with lower wood density.
- Soil CO2 emissions declined markedly (36 ± 5%) over ~50 days following girdling in three of six monitored subplots. In the other three subplots there was either a marginal decline or no response of soil CO2 emissions to girdling. The decrease in soil CO2 efflux was larger in subplots with dominance of Dipterocarpaceae.
- Synthesis. Our results indicate high spatial variation in the coupling of below-ground carbon allocation and root-rhizosphere respiration in this tropical forest, with a closer coupling in forest dominated by Dipterocarpaceae. Our findings highlight the implications of tree species composition of tropical forests in affecting the dynamics of below-ground carbon transfer and its release to the atmosphere.
中文翻译：
环剥揭示热带龙脑香林近期光合产物对土壤呼吸的巨大贡献
- 热带森林是生产力最高的陆地生态系统，每年从大气中固定超过 40 Pg 的碳。这种碳的很大一部分被分配给地下的根和与根相关的微生物。然而，很少有关于这种地下转移动力学的实证研究，特别是在碳分配过程受植物物种多样性高的影响的热带森林中。
- 我们使用了一个整体环带实验来阻止最近在婆罗洲低地热带森林中的光合产物的地下转移。通过在 0.48 公顷的土地上环绕 209 棵大树，我们确定了：（a）近期光合产物对根际呼吸的贡献；以及；(b) 地下碳供应中断、树种组成和死亡率之间的关系。
- 370 天后 209 棵树的死亡率为 62%，物种间差异很大，尤其是龙脑香科 (99%) 和山毛榉科 (100%) 的死亡率高。我们还观察到对木材密度较低的物种进行环剥后死亡风险较高。
- 在六个监测子区中的三个环剥后，土壤 CO 2排放量在约 50 天内显着下降（36 ± 5%）。在其他三个子图中，土壤 CO 2排放量对环剥有边际下降或没有响应。在以龙脑香科为主的小区中，土壤CO 2流出量的下降幅度更大。
- 合成。我们的研究结果表明，在这片热带森林中，地下碳分配和根 - 根际呼吸的耦合空间变化很大，在以龙脑香科为主的森林中耦合更紧密。我们的研究结果强调了热带森林的树种组成对影响地下碳转移及其向大气释放的动态的影响。
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