Permafrost Degradation Leads to Biomass and Species Richness Decreases on the Northeastern Qinghai-Tibet Plateau

Abstract

Degradation of permafrost with a thin overlying active layer can greatly affect vegetation via changes in the soil water and nutrient regimes within the active layer, while little is known about the presence or absence of such effects in areas with a deep active layer. Here, we selected the northeastern Qinghai-Tibet Plateau as the study area. We examined the vegetation communities and biomass along an active layer thickness (ALT) gradient from 0.6 to 3.5 m. Our results showed that plant cover, below-ground biomass, species richness, and relative sedge cover declined with the deepening active layer, while the evenness, and relative forb cover showed a contrary trend. The vegetation indices and the dissimilarity of vegetation composition exhibited significant changes when the ALT was greater than 2.0 m. The vegetation indices (plant cover, below-ground biomass, evenness index, relative forb cover and relative sedge cover) were closely associated with soil water content, soil pH, texture and nutrient content. Soil water content played a key role in the ALT–vegetation relationship, especially at depths of 30–40 cm. Our results suggest that when the ALT is greater than 2.0 m, the presence of underlying permafrost still benefits vegetation growth via maintaining adequate soil water contents at 30–40 cm depth. Furthermore, the degradation of permafrost may lead to declines of vegetation cover and below-ground biomass with a shift in vegetation species.

Simulating potential impacts of climate changes on distribution pattern and carbon storage function of high‐latitude wetland plant communities in the Xing'anling Mountains, China

“…By the end of the 21st century, permafrost in the Xing'anling Mountains would degrade dramatically due to climate warming, as shown in Figure 4. In the Northern Hemisphere, there is a symbiotic relationship between permafrost and wetlands; permafrost acts as a waterproof barrier, which holds water for wetland plant growth (Jin et al, 2008; Jin et al, 2020; Jin, Jin, Iwahana, et al, 2020). Our result shows that, as the key factor affecting the distribution of the most common wetland plant community in the Xing'anling Mountains, projected permafrost degradation plays a significant role in future wetland loss.…”

Shrinking thermokarst lakes and ponds on the northeastern Qinghai‐Tibet plateau over the past three decades

“…Permafrost degradation dries the wetlands and surface soils, causing the decrease in wet species and the expansion of drought‐tolerant plants, turning the alpine meadow into the alpine desert steppe 19 . A vegetation assessment study from the HAYR showed declining plant cover, below‐ground biomass, and species richness in response to the deepening active layer 75 …”

Responses of Plant Bud Bank Characteristics to the Enclosure in Different Desertified Grasslands on the Tibetan Plateau

“…Its climate is cold and humid, with a long winter and no summer. The annual average temperature is 1.1 °C, and the annual rainfall is 615 mm [ 38 , 39 , 40 ]. The altitude of the study area is 3440 m, and the geographical coordinates are 33°55′ N, 102°09′ E. According to the vegetation coverage and quicksand area, desertified grasslands were divided into light desertified grassland (LD), moderate desertified grassland (MD), severe desertified grassland (SD) and extreme desertified grassland (ED) ( Figure 1 , Table 1 ) [ 14 , 15 ].…”