青藏高原草本沼泽植被净初级生产力时空变化及其对气候变化的响应

Spatio⁃temporal variation in vegetation net primary productivity and its response to climate change in herbaceous marshes on the Qinghai⁃Tibet Plateau

青藏高原是我国重要的草本沼泽分布区,该地区草本沼泽对于东亚生态安全及碳循环具有重要的意义。植被净初级生产力(NPP)是反映生态系统固碳能力的重要指标,气候变化能够显著影响植被NPP。在全球气候变化背景下,青藏高原草本沼泽植被NPP的时空变化及对气候响应机理尚不明确。利用2000―2020年NPP数据和气象数据,对青藏高原草本沼泽植被NPP的时空变化及其对气候变化的响应进行分析。研究表明:青藏高原草本沼泽植被NPP多年平均值为122.80 g C/m^(2),在2000—2020年青藏高原草本沼泽植被年NPP总体呈现显著增加趋势(0.79 g C m^(-2)a^(-1)),其中增加趋势最为显著的地区集中于研究区北部。研究发现青藏高原草本沼泽植被NPP主要受年均气温影响,年均降水对青藏高原草本沼泽植被NPP的影响并不显著。在不同季节,夏季和秋季升温均能够显著增加沼泽植被NPP,其中夏季夜晚最低温升高对青藏高原草本沼泽植被生长的促进作用比白天最高温升高更显著。在全球昼夜不对称增温背景下,未来模拟青藏高原草本沼泽植被NPP时,需重点关注白天和夜晚温度变化对草本沼泽植被生长的不同影响。研究结果有助于评估青藏高原草本沼泽植被固碳潜力,并为青藏高原沼泽生态保护提供科学依据。

Herbaceous marshes have a faster rate of carbon sequestration than other types of marshes and play an essential role in regulating the regional carbon cycle and climate change.As a sensitive region to climate change,the Qinghai⁃Tibetan Plateau has large areas of herbaceous marshes,which are important for ecological security and carbon cycle in East Asia.Vegetation net primary productivity(NPP)is an important indicator of the carbon sequestration capacity of marsh ecosystems.Climate change can significantly affect the NPP of marsh ecosystems.Under the background of global climate change,the change of NPP in herbaceous marshes vegetation and its response mechanism to climate change on the Qinghai⁃Tibet Plateau are not clear.In this study,NPP data and meteorological data from 2000 to 2020 were used to analyze the temporal and spatial variation of the NPP in herbaceous marshes vegetation and its response to climate change on the Qinghai⁃Tibet Plateau.The results showed that the annual average NPP of herbaceous marshes vegetation was 122.80 g C/m^(2).The annual NPP of herbaceous marshes vegetation presented a significant increase trend(0.79 g C m^(-2)a^(-1))from 2000 to 2020,and the most significant increase was mainly concentrated in the northern part of the study area.The NPP of herbaceous marshes vegetation on the Qinghai⁃Tibet Plateau was mainly affected by the average annual temperature,and the effect of average annual precipitation on the NPP of herbaceous marshes vegetation was not significant.In different seasons,summer and autumn warming could significantly increase marsh NPP,and the increase of nighttime minimum temperature in summer had a larger positive effect on the NPP of herbaceous marshes than the daytime maximum temperature in summer.By contrast,the increase of daytime maximum temperature in autumn had a larger positive effect on the NPP of herbaceous marshes than the nighttime minimum temperature in autumn.This study highlights the different effects of seasonal climate changes on the NPP of herbaceous marshes in the Qinghai⁃Tibetan Plateau.Under the background of global diurnal asymmetric warming(faster warming trend during the night than during the day),when simulating the NPP of herbaceous marshes in the future,we should also focus on the different effects of day and night temperature changes on the vegetation growth of herbaceous marshes.The results are helpful to evaluate the carbon sequestration potential of herbaceous marshes and provide theoretical guidance for the ecological conservation of herbaceous marshes on the Qinghai⁃Tibet Plateau.