Predicting fine root lifespan from plant functional traits in temperate trees

• Although linkages of leaf and whole-plant traits to leaf lifespan have been rigorously investigated, there is a limited understanding of similar linkages of whole-plant and fine root traits to root lifespan. In comparisons across species, do suites of traits found in leaves also exist for roots, and can these traits be used to predict root lifespan?

• We observed the fine root lifespan of 12 temperate tree species using minirhizotrons in a common garden and compared their median lifespans with fine-root and whole-plant traits. We then determined which set of combined traits would be most useful in predicting patterns of root lifespan.

• Median root lifespan ranged widely among species (95–336 d). Root diameter, calcium content, and tree wood density were positively related to root lifespan, whereas specific root length, nitrogen (N) : carbon (C) ratio, and plant growth rate were negatively related to root lifespan. Root diameter and plant growth rate, together (R2 = 0.62) or in combination with root N : C ratio (R2 = 0.76), were useful predictors of root lifespan across the 12 species.

• Our results highlight linkages between fine root lifespan in temperate trees and plant functional traits that may reduce uncertainty in predictions of root lifespan or turnover across species at broader spatial scales.

Methods
See Materials and Methods in related article.

• 尽管叶片与整株植物性状同叶片寿命的关联已得到严谨探究，但学界对整株植物与细根性状同细根寿命的类似关联的认知仍较为有限。在跨物种比较中，叶片中存在的性状组合是否同样适用于根系？这些性状能否用于预测细根寿命？
• 本研究依托同质园（common garden）实验平台，采用微根窗法（minirhizotrons）观测了12种温带树木的细根寿命，并将各物种的细根中位寿命与细根及整株植物性状进行比对；随后明确了最优的组合性状集合，以预测细根寿命的变化模式。
• 不同物种的细根中位寿命跨度极大（95–336 d）。根直径、钙含量与树木木材密度与细根寿命呈正相关，而比根长（specific root length）、氮（N）:碳（C）比及植物生长速率则与细根寿命呈负相关。根直径与植物生长速率的组合（R²=0.62），或结合根N:C比（R²=0.76），可有效预测12个受试物种的细根寿命。
• 本研究结果揭示了温带树木细根寿命与植物功能性状间的关联，该发现或可降低更大空间尺度下跨物种细根寿命或细根周转（root turnover）预测的不确定性。

方法：详见相关文章的材料与方法（Materials and Methods）。