Spatiotemporal Dynamics in Vegetation GPP over the Great Khingan Mountains Using GLASS Products from 1982 to 2015

Abstract

Gross primary productivity (GPP) is an important parameter that represents the productivity of vegetation and responses to various ecological environments. The Greater Khingan Mountain (GKM) is one of the most important state-owned forest bases, and boreal forests, including the largest primeval cold-temperature bright coniferous forest in China, are widely distributed in the GKM. This study aimed to reveal spatiotemporal vegetation variations in the GKM on the basis of GPP products that were generated by the Global LAnd Surface Satellite (GLASS) program from 1982 to 2015. First, we explored the spatiotemporal distribution of vegetation across the GKM. Then we analyzed the relationships between GPP variation and driving factors, including meteorological elements, growing season length (GSL), and Fraction of Photosynthetically Active Radiation (FPAR), to investigate the dominant factor for GPP dynamics. Results demonstrated that (1) the spatial distribution of accumulated GPP (AG) in spring, summer, autumn, and the growing season varied due to three main reasons: understory vegetation, altitude, and land cover; (2) interannual AG in summer, autumn, and the growing season significantly increased at the regional scale during the past 34 years under climate warming and drying; (3) interannual changes of accumulated GPP in the growing season (AGG) at the pixel scale displayed a rapid expansion in areas with a significant increasing trend (p < 0.05) during the period of 1982-2015 and this trend was caused by the natural forest protection project launched in 1998; and finally, (4) an analysis of driving factors showed that daily sunshine duration in summer was the most important factor for GPP in the GKM and this is different from previous studies, which reported that the GSL plays a crucial role in other areas.

The Global Land Surface Satellite (GLASS) Product Suite

“…The GLASS GPP product has been widely used to examine the spatial and temporal variations in GPP (Han et al 2015;Hu et al 2018;Ma et al 2015;Wang et al 2015;Xu et al 2013). For example, Yuan et al (2019) used the GLASS GPP product to investigate the impacts of atmospheric VPD on global terrestrial GPP and found persistent widespread decreases in GPP after the late 1990s due to increases in VPD, which offset the positive CO2 fertilization effect.…”

“…the MODIS FAPAR product, especially for croplands. Hu et al (2018) also incorporated the GLASS FAPAR product into their GPP calculations.…”

Soil fungal and bacterial communities in southern boreal forests of the Greater Khingan Mountains and their relationship with soil properties

“…www.nature.com/scientificreports/ best-preserved and largest primeval forest in China, is one of the few locations in China with boreal forests 19 . It is also the southernmost boreal forest biome in the world 20 .…”

Distribution and Driving Factors of Forest Swamp Conversions in a Cold Temperate Region

“…Forest swamping was an important means of forest swamp formation in cold temperate regions. Dense canopy forests and the permafrost layers under the forests in cold temperate regions provided cold and wet conditions for swamp development [ 82 , 83 ]. Our results showed that forest swamping widely occurred under such conditions in the study area [ 84 ].…”