Cordeiro Amanda L, Norby Richard J, Andersen Kelly M, Valverde-Barrantes Oscar, Fuchslueger Lucia, Oblitas Erick, Hartley Iain P, Iversen Colleen M, Gonçalves Nathan B, Takeshi Bruno, Lapola David M, Quesada Carlos A
Instituto Nacional de Pesquisas da Amazônia - INPA Manaus Brazil.
Colorado State University - CSU Fort Collins CO USA.
Plant Environ Interact. 2020 Apr 22;1(1):3-16. doi: 10.1002/pei3.10010. eCollection 2020 Jun.
A common assumption in tropical ecology is that root systems respond rapidly to climatic cues but that most of that response is limited to the uppermost layer of the soil, with relatively limited changes in deeper layers. However, this assumption has not been tested directly, preventing models from accurately predicting the response of tropical forests to environmental change.We measured seasonal dynamics of fine roots in an upper-slope plateau in Central Amazonia mature forest using minirhizotrons to 90 cm depth, which were calibrated with fine roots extracted from soil cores.Root productivity and mortality in surface soil layers were positively correlated with precipitation, whereas root standing length was greater during the dry periods at the deeper layers. Contrary to historical assumptions, a large fraction of fine-root standing biomass (46%) and productivity (41%) was found in soil layers deeper than 30 cm. Furthermore, root turnover decreased linearly with soil depth.Our findings demonstrate a relationship between fine-root dynamics and precipitation regimes in Central Amazonia. Our results also emphasize the importance of deeper roots for accurate estimates of primary productivity and the interaction between roots and carbon, water, and nutrients.
热带生态学中一个常见的假设是，根系会迅速对气候线索做出反应，但这种反应大多局限于土壤的最上层，较深层的变化相对有限。然而，这一假设尚未得到直接验证，导致模型无法准确预测热带森林对环境变化的反应。我们利用微型根钻在亚马逊中部成熟森林的上坡高原地区测量了至90厘米深度的细根季节性动态，并通过从土芯中提取的细根进行校准。表层土壤层的根系生产力和死亡率与降水量呈正相关，而深层土壤在干旱时期的根长则更长。与以往的假设相反，在深度超过30厘米的土壤层中发现了很大一部分细根现存生物量（46%）和生产力（41%）。此外，根周转率随土壤深度呈线性下降。我们的研究结果证明了亚马逊中部细根动态与降水模式之间的关系。我们的结果还强调了深层根系对于准确估算初级生产力以及根系与碳、水和养分之间相互作用的重要性。
