Earth and Environmental Sciences Area, Lawrence Berkeley National Laboratory, Berkeley, California, USA.
Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, USA.
Glob Chang Biol. 2022 Sep;28(18):5560-5574. doi: 10.1111/gcb.16318. Epub 2022 Jul 10.
Crown damage can account for over 23% of canopy biomass turnover in tropical forests and is a strong predictor of tree mortality; yet, it is not typically represented in vegetation models. We incorporate crown damage into the Functionally Assembled Terrestrial Ecosystem Simulator (FATES), to evaluate how lags between damage and tree recovery or death alter demographic rates and patterns of carbon turnover. We represent crown damage as a reduction in a tree's crown area and leaf and branch biomass, and allow associated variation in the ratio of aboveground to belowground plant tissue. We compare simulations with crown damage to simulations with equivalent instant increases in mortality and benchmark results against data from Barro Colorado Island (BCI), Panama. In FATES, crown damage causes decreases in growth rates that match observations from BCI. Crown damage leads to increases in carbon starvation mortality in FATES, but only in configurations with high root respiration and decreases in carbon storage following damage. Crown damage also alters competitive dynamics, as plant functional types that can recover from crown damage outcompete those that cannot. This is a first exploration of the trade-off between the additional complexity of the novel crown damage module and improved predictive capabilities. At BCI, a tropical forest that does not experience high levels of disturbance, both the crown damage simulations and simulations with equivalent increases in mortality does a reasonable job of capturing observations. The crown damage module provides functionality for exploring dynamics in forests with more extreme disturbances such as cyclones and for capturing the synergistic effects of disturbances that overlap in space and time.
树冠损伤在热带森林的冠层生物量周转中占比超过 23%，是树木死亡率的重要预测因子；然而，植被模型通常不考虑树冠损伤。我们将树冠损伤纳入功能组装陆地生态系统模拟器 (FATES) 中，以评估损伤与树木恢复或死亡之间的时间滞后如何改变人口动态和碳周转模式。我们将树冠损伤表示为树木树冠面积和叶片及树枝生物量的减少，并允许地上和地下植物组织比例的相关变化。我们将带有树冠损伤的模拟与具有等效即时死亡率增加的模拟进行比较，并将基准结果与来自巴拿马巴罗科罗拉多岛 (BCI) 的数据进行对比。在 FATES 中，树冠损伤导致生长速率下降，与 BCI 的观测结果相匹配。树冠损伤会导致 FATES 中碳饥饿死亡率增加，但仅在根系呼吸率高且损伤后碳储存减少的情况下才会增加。树冠损伤还会改变竞争动态，因为能够从树冠损伤中恢复的植物功能类型会胜过那些无法恢复的类型。这是对新的树冠损伤模块的附加复杂性与改进的预测能力之间权衡的首次探索。在 BCI 这个没有经历过高水平干扰的热带森林中，树冠损伤模拟和具有等效死亡率增加的模拟都能很好地捕捉到观测结果。树冠损伤模块提供了功能，可用于探索具有更极端干扰（如气旋）的森林中的动态，还可捕捉空间和时间上重叠的干扰的协同效应。
