长白山森林景观历史重构的种源区划分及验证

Provenance zone allocation and validation for reconstruction of historical forest landscape in Changbai Mountains

为了研究当前长白山森林植被分布和演替进程坡向差异形成的机理,重构了800年前长白山火山大喷发后的森林植被演替动态,强调种子传播在火山灰裸地上森林植被演替中的作用。火山喷发后,种源区是没有受到破坏的原始森林生态系统,在不考虑外界干扰的理想情况下,其森林结构和功能长期保持相对稳定状态,并为火山灰裸地上的植被恢复提供种子。本文综合前人研究结果,划分了长白山火山大喷发后的火山灰裸地的范围,并把火山灰裸地外围宽15 km的区域定义为种源区。为了论证种源区是一个稳定的森林生态系统,同时为火山灰裸地上的森林景观重构奠定基础,本文应用空间直观森林景观模型LANDIS PRO 7.0模拟种源区800年的森林地上生物量和树种分布面积的动态变化,用森林调查数据和文献数据对模型结果进行校验和验证。结果表明,种源区的森林地上生物量在阔叶红松林带和云冷杉林带以及整个景观水平上保持稳定波动状态。阔叶红松林带和云冷杉林带主要树种的模型初始化生物量以及景观水平上长期模拟的生物量在野外调查和文献研究的结果范围内。拟合优度检验值珋e(%)、MAE(%)、RMSE(%)和ME均小于10,模型初始化生物量和长期模拟结果与野外调查和文献研究的结果差异较小。合理划分种源区并对其模拟结果进行校验和验证,对种源区的森林生态系统进行有效的稳定性分析,有助于提高火山灰裸地上森林植被演替模拟的准确性,对正确解释当前长白山各坡向森林植被分布规律和演替进程的差异、预测未来长白山森林植被演替动态具有重要意义。

For the sake of studying the formation mechanism of forest distribution and succession process differences among four terrestrial aspects of Changbai Mountains, the forest succession dynamics after the volcano super eruption occurred 800 years ago was to be reconstructed. Espe- cially, the role of seed dispersal in the forest succession on tephra bare land was emphasized. Provenance zone was an intact and primeval forest ecological system after the volcano eruption, of which the forest composition, stand structure and succession dynamics can keep stable in long term regardless of any interference, and it provided sufficient seeds for the vegetation recovery on tephra bare land. This study defined the distribution range of tephra bare land after Changbai vol- cano erupted by integrating previous research results and a 15-km extension outside the tephra bare land as provenance zone. In order to prove that provenance zone is a stable forest ecosystem and pave the way for the forest landscape reconstruction on tephra bare land, a spatially explicittbrest landscape model LANDIS PRO 7.0 was used to simulate the 800 years long dynamic chan- ges of forest aboveground biomass and species distribution area in provenance zone. Moreover, the simulation results were calibrated and validated using inventory data and data derived from published papers. The results showed that forest aboveground biomass in provenance zone kept relatively stable either in broad-leaved Korean pine forest belt, spruce-fir forest belt or at the whole landscape scale. Both the initialization biomass of major species in broad-leaved Korean pine forest belt, spruce-fir forest belt and the long-term results simulated at landscape scale were in the range of field survey and previous researches. The goodness of fit test value e （%） , MAE （%）, RMSE （%） and ME were less than 10. Little differences were found between model ini- tialization biomass, long-term simulation results and field survey or previous researches. A rea- sonable provenance zone allocation, calibration and validation for the simulation results and an effective stability analysis for the forest ecosystem in provenance zone were beneficial to enhan- cing the veracity of forest succession simulation on tephra bare land. It is of significance to explain the present differences of forest distribution regulations and succession processes among different aspects of Changbai Mountains as well as to predict its future forest succession dynamics.