关键词: 南海中西部海域, 碳氮稳定同位素, 营养生态位, 鸢乌贼

Abstract: In this study, we selected typical subalpine meadow distributed in Shanxi Province to explore the geographical distribution of vegetation biomass of subalpine meadow at the community level. After biomass was harvested, the variation of total biomass (TB), aboveground biomass (AGB), below-ground biomass (BGB) and root:shoot ratio (R/S) were analyzed at different geographical gradients (longitude, latitude, and altitude). The results showed that TB, AGB, and BGB substantially varied across the region. The variation was the largest for the AGB with a range of 32.50-756.00 g·m^-2, followed by the BGB with a range of 140.50-1586.50 g·m^-2. The variation in TB was the smallest with a range of 248.25-2342.50 g·m^-2. The TB decreased significantly with altitude (P<0.05), whereas increased slowly with longitude (P>0.05), and slightly decreased with latitude (P>0.05). The largest TB was found at 1700-1800 m, 113.4-113.85°E, 35-35.5°N (with an average of 896 g·m^-2). The AGB decreased significantly with increasing latitude and altitude (P<0.001), and gradually increased with longitude (P<0.05). The largest AGB was found at 1700-1800 m, 112.05-112.5°E, 35-35.5°N (with an average of 366.06 g·m^-2). The BGB showed a trend of “decreaseincreasedecrease” as the latitude increased, but increased slightly overall (P>0.05), slightly increased with longitude (P>0.05), and increased significantly with the increases of altitude (P<0.05). The maximum BGB was found at 3000-3100 m, 113.4-113.85°E, 35-35.5°N (with an average 745.63 g·m^-2). The R/S increased significantly with increasing latitude and altitude (P<0.05), slightly increased with longitude (P>0.05), and showed a significant exponential function with latitude and altitude (P<0.05), characterized by isometric growth (average power exponent of 1.025). Results from redundancy analysis showed that latitude and altitude had greater impacts on the biomass of subalpine meadow, while longitude had less impact. The AGB was negatively correlated with longitude, latitude, and altitude. Subalpine meadow allocated more biomass to belowground parts.

Key words: trophic niche, Sthenoteuthis oualaniensis, central and western South China Sea, carbon and nitrogen stable isotopes