Plant biomass in three subalpine grasslands on Qinghai-Tibetan Plateau

Aims: Multiple studies have addressed the relationship between plant
biomass and species richness, often reporting a hump-shaped curve.
However, such research in natural grassland was mostly conducted in
temperate, arid and semiarid areas, with few studies focused on alpine
regions. Moreover, in most cases, plant community biomass was the main
variable of interest, with few studies considering also plant individual
biomass, calculated by dividing plant community biomass by plant
abundance. Location: To explore the relationship between plant biomass and
species richness in subalpine regions, a field survey was conducted in
three locations with fenced subalpine grasslands on the Qinghai-Tibetan
Plateau in China in 2020 and 2023. Methods: Plant aboveground biomass and
species richness were recorded along four transects in each location.
Analyses were performed using both plant community biomass and plant
individual biomass to test whether using a different biomass measure
affected the plant biomass-species richness relationship. Results:
Location and year × location significantly affected species richness,
plant community biomass and plant individual biomass. Curve estimations
demonstrated a positive nonlinear relationship between plant community
biomass and species richness, and a negative nonlinear relationship
between plant individual biomass and species richness. These patterns were
modified by the locations of the three grasslands. Competition can explain
some of the different patterns between plant community biomass-species
richness relationship and plant individual biomass-species richness
relationship. Conclusions: In general, the choice of biomass approach
affected the relationship between plant biomass and species richness in
subalpine grasslands, which indicates that plant abundance impacts plant
biomass-species richness relationship. Future research should consider
further modulators and drivers when exploring the plant biomass-species
richness relationship in grasslands in a climate change context.