Abstract
ABSTRACT Because permafrost is extremely sensitive to climate change, it is of great importance to understand the relationship between permafrost and vegetation biomass. This study aims to reveal the impacts of permafrost on above- and belowground vegetation biomass on the northern Qinghai-Tibetan Plateau. Soil temperature, moisture, active-layer thickness, vegetation coverage, aboveground biomass (AGB), belowground biomass (BGB), and soil organic carbon were investigated in the growing seasons during 2014–2016. The average AGB and BGB in the growing seasons were 0.036 and 0.83 g cm−2, respectively. The AGB was significantly positively correlated with BGB, soil moisture, and soil organic carbon content, but was significantly negatively correlated with mean annual ground temperature and active-layer thickness, suggesting that permafrost degradation can potentially decrease vegetation growth. The BGB was positively correlated with active-layer thickness and was negatively correlated with soil moisture. This study suggests that permafrost degradation can decrease the soil moisture on the northern Qinghai-Tibetan Plateau and thus decrease AGB. The decreased soil moisture can also lead to lower BGB, while the vegetation in drier soils tends to have higher BGB to access more water resources for plant growth.
Highlights
Permafrost affects the soil hydrological regime because of the relatively impermeable layer of the permafrost table (O’Donnell et al 2012)
The aboveground biomass (AGB) was significantly positively correlated with belowground biomass (BGB), soil moisture, and soil organic carbon content, but was significantly negatively correlated with mean annual ground temperature and active-layer thickness, suggesting that permafrost degradation can potentially decrease vegetation growth
This study suggests that permafrost degradation can decrease the soil moisture on the northern Qinghai-Tibetan Plateau and decrease AGB
Summary
Permafrost affects the soil hydrological regime because of the relatively impermeable layer of the permafrost table (O’Donnell et al 2012). Because soil moisture and nutrients are major environmental factors controlling vegetation distribution (Shen et al 2008; Wardle et al 2004), permafrost degradation will inevitably affect vegetation growth because permafrost degradation usually means increasing ground temperature and deepening active-layer thickness, which further affect soil moisture conditions (Wu and Zhang 2010; Zhao et al 2010). In comparison with the active layers in arctic regions, which are largely less than 1 m (Ping et al 2015), the active layers in low-latitude permafrost regions are usually about 2 m or deeper (Qin et al 2016; Wu et al 2016b). It can be expected that permafrost degradation may decrease the biomass in low-latitude permafrost regions. There are no reports about the relationship between vegetation biomass and active layer, and this knowledge gap hinders our understanding of the effects of permafrost degradation on ecosystem functions
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