气候变化背景下森林动态模拟研究综述

Review of forest dynamics simulation under the background of climate change:a case study of Forest Gap Model and Dynamic Global Vegetation Model

在全球气候变化背景下,森林的地理分布与生态过程研究受到越来越多的关注。森林对气候变化的响应是一个复杂的过程,在已有模拟方法中,林窗模型和全球植被动态模型由于考虑了气候作用下植被的演替与更新等机理,能较为合理地模拟气候变化背景下森林的瞬态响应,是目前气候变化研究的热点之一。全球植被动态模型以植物功能类型(PFTs)表示区域森林植被组成,通过模拟PFTs比例的变化来反映森林地理分布格局的动态变化。通过回顾上述两类模型的发展历程,梳理了模型在模拟研究森林地理分布及生态过程中,对过去和未来气候变化的潜在响应方面的应用,并针对模型中存在的不足,提出今后应在动态模型多尺度研究、加强模型对非气候因子的描述、模型间比较、多源遥感数据与模型同化等方面开展重点研究。

Under the background of global climate change, forest geographic distribution and ecological processes have attracted increasingly more attention of the research community. Response of forest to climate change is a complex process. In the past decade, a growing number of researchers have simulated the climate effects on plant species or vegetation by using various models. Among the simulation models, the Forest Gap Models(FGMs) and Dynamic Global Vegetation Models(DGVMs) consider mechanism like vegetation succession and regeneration under climatic impact, and can reasonably simulate the transient response of forest in the context of climate change, which is one of the hot topics in climate change research. FGMs simulate forest change over time using spatially referenced data on a broad spatial scale(i.e. landscape scale), generally larger than a single forest stand. Spatial interaction among forest stands is a key component of such models. These models can incorporate other spatiotemporal processes such as natural disturbances(e.g. wildfires, hurricanes, outbreaks of native and exotic invasive pests and diseases) and human interference. These models are increasingly used as tools for studying forest management, ecological assessment, restoration planning and climate change. DGVMs are powerful tools to simulate past and future vegetation patterns and associated biogeochemical cycles. Most DGVMs are limited by how they define vegetation and their simplistic representation of competition. They use Plant Functional Types(PFTs) to show regional forest vegetation composition, and simulate proportional changes of PFTs to reflect forest geographic pattern dynamics. DGVMs have shown that forest dynamics could dramatically alter the response of the global climate system over the next century. But there is little agreement among different DGVMs, making forest dynamic one of the greatest sources of uncertainty in predicting future climate. DGVMs' predictions could be strengthened by integrating the ecological realities of biodiversity and height-structured competition for light, facilitated with recent advances in the mathematics of forest modeling,ecological understanding of diverse forest communities, and the availability of forest inventory data. In this paper, we review the development, components and types of the models and discuss the application of simulating potential response of forest geographic distribution and ecological processes to past and future climate change.As for deficiencies in current development and application of FGMs and DGVMs, key research should be carried out in multi-scale study of dynamic models and enhancement of the model description of the non-climatic factors, comparison among models, and assimilation of multi-source remote sensing data and models, among others. In conclusion, only when these models reflect more accurately realistic relationships between plant species or vegetation and climate variables, can they be employed to simulate responses of plant species or vegetation to rapid change in climate.