基于InTEC模型的塔河森林净初级生产力影响因子定量分析

森林净初级生产力(NPP)是反映森林碳源/汇能力的重要参数,其时空变化同时受气象变化(大气温度、降水等)、大气成分变化(CO₂浓度、N沉降)和各种森林干扰的影响.然而,目前影响森林NPP变化的关键因子尚不明确.为了探究这一问题,本研究在综合考虑InTEC模型的干扰和非干扰因子的基础上,重新模拟了不同立地指数下的NPP-林龄关系,并嵌入1987—2015年林火数据,模拟1901—2015年塔河森林平均NPP变化特征,设计9种模拟情景定量分析1961—2015年不同影响因子对塔河森林NPP变化的贡献,并探究塔河森林NPP年际以及年代变化的主要影响因子,为森林经营提供指导性策略.结果表明: 1901—1960年,塔河森林NPP的变化趋势较为平稳,1960年以后NPP随干扰因子变化趋势显著.林火和立地指数(SCI)的引入,均在不同时间对NPP的分布特征产生了不同影响.1960年以后,塔河森林NPP大幅变化的主要原因是森林年龄和林火的干扰,其年际平均贡献率为-49%,其次是降水和CO₂,分别为-28%和17%,气温和氮沉降的平均贡献率分别为5%和1%.

Quantitative analysis of impact factors on net primary productivity of Tahe forest based on InTEC model

Net primary productivity (NPP) is an important character reflecting forest carbon source/sink capability, with the spatial-temporal change of which being affected by meteorological change (air temperature, precipitation, etc.), changes in atmospheric composition (CO₂ concentration, nitrogen deposition) and various disturbances. However, the key factor driving the changes of forest NPP is still unclear. In order to explore this issue, the relationship between NPP and forest age under different site class index (SCI) was re-simulated and embedded the forest fire data in 1987-2015 to simulate the change characteristics of average NPP of Tahe forest from 1901 to 2015 by comprehensively considering the disturbance and non-disturbance factors of InTEC model, nine scenarios were considered to quantitatively analyze the contribution of different influence factors to the changes of NPP in Tahe forest from 1961 to 2015, and to explore the main influencing factors of the interannual and chronological changes of the Tahe forest NPP to provide a guiding strategy for forest management. The results showed that NPP in Tahe forest was relatively stable from 1901 to 1960, but had a significant trend with the disturbance factors after 1960. The embedding of forest fire and SCI data had different effects on the distribution characteristics of NPP at different times. After 1960, the main reason for the significant change of NPP in Tahe forest was stand age and fire disturbance, with an average annual contribution rate of -49%, followed by precipitation and CO₂, which were -28% and 17% respectively. The average contribution rates of temperature and nitrogen deposition were only 5% and 1%, respectively.