Nitrogen (N) deposition has increased globally and has profoundly influenced the structure and function of grasslands. Previous studies have discussed how N addition affects aboveground biomass (AGB), but the effects of N addition on the AGB of different functional groups in grasslands remain unclear. We conducted a meta-analysis to identify the responses of AGB and the AGB of grasses (AGB_grass) and forbs (AGB_forb) to N addition across global grasslands. Our results showed that N addition significantly increased AGB and AGB_grass by 31 and 79%, respectively, but had no significant effect on AGB_forb. The effects of N addition on AGB and AGB_grass increased with increasing N addition rates, but which on AGB_forb decreased. Although study durations did not regulate the response ratio of N addition for AGB, which for AGB_grass increased and for AGB_forb decreased with increasing study durations. Furthermore, the N addition response ratios for AGB and AGB_grass increased more strongly when the mean annual precipitation (MAP) was 300–600 mm but decreased with an increase in the mean annual temperature (MAT). AGB_forb was only slightly affected by MAP and MAT. Our findings suggest that an acceleration of N deposition will increase grassland AGB by altering species composition.

Planted forest plays a significant role in carbon sequestration and climate change mitigation; however, little information has been available on the distribution patterns of carbon pools with stand ages in Pinus massoniana Plantations. We investigated the biomass stock and carbon sequestration across a chronosequence (3-, 5-, 7-, 9-, 12-, 15-, 19-, 29-, 35- and 42-year) of stands with the main objectives: (1) to determine the biomass and carbon stock of the forest ecosystem; and (2) to identify factors influencing their distribution across the age series. Simple random sampling was used for collecting field data in the ten (10) stand ages. Three 20 × 20 m standard plots were laid out in February 2015 across the chronosequence. The diameter at breast height (DBH) and tree height (H) of each tree within each plot were measured using calipers and height indicator. Sub-plots of 2 × 2 m were established in each main plot for collecting soil samples at a 0–30- and 30–60-cm depth. Plantation biomass increased with increasing stand ages, ranging from 0.84 tonnes per hectare (t·ha⁻¹) in the three-year stand to 252.35 t·ha⁻¹ in the 42-year stand. The aboveground biomass (AGB) contributed 86.51%; the maximum value is 300-times the minimum value. Carbon concentrations and storage in mineral soil decreased with increasing soil depth, but were controlled by the management history of the ecosystem. The total ecosystem carbon storage varies with stand ages, ranging from 169.90 t·ha⁻¹ in the five-year plantation to 326.46 t·ha⁻¹ in the 42-year plantation, of which 80.29% comes from the mineral soil carbon and 19.71% from the vegetation. The ratio of the total carbon sequestration by the 42-year to the three-year stand was 1.70, implying substantial amounts of carbon accumulation during the transition period from young to mature-aged trees. The forest ecosystem had the capacity of storing up to 263.16 t·ha⁻¹ carbon, assisting in mitigating climate change by sequestrating 965.83 t·ha⁻¹ of CO₂ equivalents, indicating that the forest is an important carbon sink.