基于Biome-BGC模型的刺槐人工林生产力和内在水分利用效率研究

目的 探究刺槐人工林生产力和内在水分利用效率(iWUE)的影响因子及其对气候变化的响应。 方法 使用过程模型Biome-BGC对我国半湿润区内比较干旱的陕西省白水县和比较湿润的河南省民权县的刺槐人工林模拟净初级生产力(NPPs),并用实测净初级生产力(NPPm)数据进行验证,根据模拟结果计算生态系统内在水分利用效率(iWUEs)。分析两地刺槐人工林的生态系统与树轮iWUE变化趋势的差异。 结果 两地刺槐年际生物量均随年龄增大而首先迅速增加,具有明显的幼龄效应,随后逐步稳定并在一定范围内波动;在不包含幼龄林数据时,两地刺槐人工林NPPs与NPPm呈极显著正相关(P＜0.01),树轮年际内在水分利用效率(iWUEm)则均呈波动上升趋势。白水县刺槐林的iWUEs与iWUEm呈极显著负相关(P＜0.01),但民权县刺槐林的iWUEs与iWUEm呈显著正相关(P＜0.05)。 结论 温度是影响iWUEm的关键因子,年降水量和大气CO2浓度是影响生物量的关键因子。Biome-BGC 模型能较好地模拟幼龄林以后的刺槐人工林的NPP,在半湿润区内湿润程度不同地点之间,刺槐人工林的生长关系一致,但碳水关系比较复杂。

Productivity and Intrinsic Water Use Efficiency of Robinia pseudoacacia Plantations based on Biome-BGC Model

Objective To explore the impact factors of productivity and intrinsic water use efficiency (iWUE) of plantation and their responses to climate change. Method Biome-BGC, a process-based model, was used to simulate the net primary productivity (NPP) of Robinia pseudoacacia plantation (NPPs) in Baishui County (BS) and Minquan County (MQ) in China and the simulation results were verified with the measured NPP (NPPm). The intrinsic water use efficiency of the ecosystem was calculated according to the simulation results(iWUEs). The differences of the variation of iWUE between the ecosystem and tree-ring(iWUEm) of R. pseudoacacia plantation at two sites were also analyzed. Results Annual biomass of both sites increased rapidly with age at first time, with obvious juvenile effect, and then fluctuated within a certain range. Without the young forest data, the NPPs and NPPm of R. pseudoacacia plantation at the two sites showed a significant positive correlation (P<0.01). The iWUEs and iWUEm of BS showed a highly significant negative correlation (P<0.01), while a reverse pattern was observed at MQ site (P<0.05). Conclusion Temperature is the key factor affecting iWUEm, and annual precipitation and atmospheric CO2 concentration are the important factors affecting biomass. Biome-BGC model can well simulate the NPP of R. pseudoacacia plantation after the young stage. The growth relationship of R. pseudoacacia plantation is consistent between sites with different humidity levels in semi-humid regions, but the relationship between carbon and water is more complex.