Department of Ecosystem Science and Management, The Pennsylvania State University, 109 Tyson Building, University Park, PA 16802, USA.
Glob Chang Biol. 2013 Jun;19(6):1697-708. doi: 10.1111/gcb.12163. Epub 2013 Mar 25.
Fine root dynamics control a dominant flux of carbon from plants and into soils and mediate potential uptake and cycling of nutrients and water in terrestrial ecosystems. Understanding of these patterns is needed to accurately describe critical processes like productivity and carbon storage from ecosystem to global scales. However, limited observations of root dynamics make it difficult to define and predict patterns of root dynamics across broad spatial scales. Here, we combine species-specific estimates of fine root dynamics with a model that predicts current distribution and future suitable habitat of temperate tree species across the eastern United States (US). Estimates of fine root lifespan and turnover are based on empirical observations and relationships with fine root and whole-plant traits and apply explicitly to the fine root pool that is relatively short-lived and most active in nutrient and water uptake. Results from the combined model identified patterns of faster root turnover rates in the North Central US and slower turnover rates in the Southeastern US. Portions of Minnesota, Ohio, and Pennsylvania were also predicted to experience >10% increases in root turnover rates given potential shifts in tree species composition under future climate scenarios while root turnover rates in other portions of the eastern US were predicted to decrease. Despite potential regional changes, the average estimates of root lifespan and turnover for the entire study area remained relatively stable between the current and future climate scenarios. Our combined model provides the first empirically based, spatially explicit, and spatially extensive estimates of fine root lifespan and turnover and is a potentially powerful tool allowing researchers to identify reasonable approximations of forest fine root turnover in areas where no direct observations are available. Future efforts should focus on reducing uncertainty in estimates of root dynamics by better understanding how climate and soil factors drive variability in root dynamics of different species.
细根动态控制着植物向土壤中碳的主要通量，并介导陆地生态系统中养分和水分的潜在吸收和循环。为了准确描述从生态系统到全球尺度的生产力和碳储存等关键过程，需要了解这些模式。然而，细根动态的有限观测使得难以在广泛的空间尺度上定义和预测细根动态的模式。在这里，我们将细根动态的种特异性估计与一个模型相结合，该模型预测了美国东部温带树种的当前分布和未来适宜栖息地。细根寿命和周转率的估计是基于经验观察以及与细根和整个植物特征的关系得出的，并且明确适用于相对寿命较短且在养分和水分吸收中最活跃的细根池。综合模型的结果确定了美国中北部更快的根周转率模式和美国东南部较慢的周转率模式。根据未来气候情景下树种组成的潜在变化，预测明尼苏达州、俄亥俄州和宾夕法尼亚州的部分地区根周转率将增加超过 10%，而美国东部其他地区的根周转率预计将下降。尽管存在潜在的区域变化，但整个研究区域的根寿命和周转率的平均估计在当前和未来气候情景之间仍然相对稳定。我们的综合模型提供了第一个基于经验、空间明确和空间广泛的细根寿命和周转率估计，并且是一种潜在的强大工具，允许研究人员在没有直接观测的情况下识别森林细根周转率的合理近似值。未来的工作应侧重于通过更好地了解气候和土壤因素如何驱动不同物种根动态的变异性来减少根动态估计的不确定性。
