Assessing uncertainties in a second-generation dynamic vegetation model caused by ecological scale limitations
Assessing uncertainties in a second-generation dynamic vegetation model caused by ecological scale limitations
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DOI：
10.1111/j.1469-8137.2010.03340.x
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发表时间：
2010-01-01
期刊：
影响因子：
9.4
通讯作者：
Woodward, F. Ian
中科院分区：
文献类型：
--
作者：
Fisher, Rosie;McDowell, Nate;Woodward, F. Ian
最近开发的第二代动态全球植被模型（DGVM）明确地代表了干扰、光的垂直竞争和演替的生态动态。在这里，我们介绍了改进的第二代 DGVM，并研究了这些模型未代表的二维空间尺度上的人口统计过程的表示如何影响预测的群落结构以及生态系统对气候变化的响应。我们研究的关键人口统计过程是种子平流、种子混合、树苗生存、竞争排斥和植物死亡率。我们在模拟亚马逊雨林生态系统的背景下改变了这些参数，该生态系统包含七种植物功能类型（PFT），这些植物功能类型沿着生长和饥饿引起的死亡风险之间的权衡面变化。改变五个不受约束的参数产生了从单一栽培到七种 PFT 平等共同主导的群落结构。当暴露于气候变化情景时，二氧化碳施肥和植物死亡率增加的相互竞争影响导致模拟之间的生态系统生物量存在很大差异，21世纪中叶的生物量预测范围为1.5至27.0 kg C m-2。使用生物量、叶面积指数（LAI）、总初级生产力（GPP）和净初级生产力（NPP）的当代观测范围过滤结果并没有显着限制潜在结果。我们得出的结论是，人口统计过程代表了 DGVM 预测中不确定性的一大来源。
P>Second-generation Dynamic Global Vegetation Models (DGVMs) have recently been developed that explicitly represent the ecological dynamics of disturbance, vertical competition for light, and succession. Here, we introduce a modified second-generation DGVM and examine how the representation of demographic processes operating at two-dimensional spatial scales not represented by these models can influence predicted community structure, and responses of ecosystems to climate change.The key demographic processes we investigated were seed advection, seed mixing, sapling survival, competitive exclusion and plant mortality. We varied these parameters in the context of a simulated Amazon rainforest ecosystem containing seven plant functional types (PFTs) that varied along a trade-off surface between growth and the risk of starvation induced mortality.Varying the five unconstrained parameters generated community structures ranging from monocultures to equal co-dominance of the seven PFTs. When exposed to a climate change scenario, the competing impacts of CO2 fertilization and increasing plant mortality caused ecosystem biomass to diverge substantially between simulations, with mid-21st century biomass predictions ranging from 1.5 to 27.0 kg C m-2.Filtering the results using contemporary observation ranges of biomass, leaf area index (LAI), gross primary productivity (GPP) and net primary productivity (NPP) did not substantially constrain the potential outcomes. We conclude that demographic processes represent a large source of uncertainty in DGVM predictions.