Climate warming has caused a widespread increase in extreme fire weather, making forest fires longer-lived and larger^1–3. The average forest fire size in Canada, the USA and Australia has doubled or even tripled in recent decades^4,5. In return, forest fires feed back to climate by modulating land–atmospheric carbon, nitrogen, aerosol, energy and water fluxes^6–8. However, the surface climate impacts of increasingly large fires and their implications for land management remain to be established. Here we use satellite observations to show that in temperate and boreal forests in the Northern Hemisphere, fire size persistently amplified decade-long postfire land surface warming in summer per unit burnt area. Both warming and its amplification with fire size were found to diminish with an increasing abundance of broadleaf trees, consistent with their lower fire vulnerability compared with coniferous species^9,10. Fire-size-enhanced warming may affect the success and composition of postfire stand regeneration^11,12 as well as permafrost degradation¹³, presenting previously overlooked, additional feedback effects to future climate and fire dynamics. Given the projected increase in fire size in northern forests^14,15, climate-smart forestry should aim to mitigate the climate risks of large fires, possibly by increasing the share of broadleaf trees, where appropriate, and avoiding active pyrophytes.

Unleashing the land sector’s potential for climate mitigation requires purpose-driven changes in land management. However, contributions of past management changes to the current global and regional carbon cycles remain unclear. Here, we use vegetation modelling to reveal how a portfolio of ecological restoration policies has impacted China’s terrestrial carbon balance through developing counterfactual ‘no-policy’ scenarios. Pursuing conventional policies and assuming no changes in climate or atmospheric carbon dioxide (CO₂) since 1980 would have led China’s land sector to be a carbon source of 0.11 Pg C yr⁻¹ for 2001–2020, in stark contrast to a sink of 175.9 Tg C yr⁻¹ in reality. About 72.7% of this difference can be attributed to land management changes, including afforestation and reforestation (49.0%), reduced wood extraction (21.8%), fire prevention and suppression (1.6%) and grassland grazing exclusion (0.3%). The remaining 27.3% come from changes in atmospheric CO₂ (42.2%) and climate (−14.9%). Our results underscore the potential of active land management in achieving ‘carbon-neutrality’ in China.

Forest ecosystems play an important role in the global carbon cycle. Clarifying the large-scale dynamics of net primary productivity (NPP) and its correlation with climatic factors is essential for national forest ecology and management. Hence, this study aimed to explore the effects of major climatic factors on the Carnegie–Ames–Stanford Approach (CASA) model-estimated NPP of the entire forest and all its corresponding vegetation types in China from 1982 to 2015. The spatiotemporal patterns of interannual variability of forest NPP were illustrated using linear regression and geographic information system (GIS) spatial analysis. The correlations between forest NPP and climatic factors were evaluated using partial correlation analysis and sliding correlation analysis. We found that over thirty years, the average annual NPP of the forests was 887 × 10¹² g C/a, and the average annual NPP per unit area was 650.73 g C/m²/a. The interannual NPP of the entire forest and all its corresponding vegetation types significantly increased (p < 0.01). The increase in the NPP of evergreen broad-leaved forests was markedly substantial among forest types. From the spatial perspective, the NPP of the entire forest vegetation gradually increased from northwest to southeast. Over the years, the proportions of the entire forest and all its corresponding vegetation types with a considerable increase in NPP were higher than those with a significant decrease, indicating, generally, improvements in forest NPP. We also found climatic factors variably affected the NPP of forests over time considering that the rise in temperature and solar radiation improved the interannual forest NPP, and the decline in precipitation diminished the forest NPP. Such varying strength of the relationship between the interannual forest NPP and climatic factors also varied across many forest types. Understanding the spatiotemporal pattern of forest NPP and its varying responses to climatic change will improve our knowledge to manage forest ecosystems and maintain their sustainability under a changing environment.

Wildfire is the most prevalent natural disturbance in the North American boreal forest (NABF) and can cause postfire land surface temperature change (ΔT_fire) through biophysical processes. Fire regimes, such as fire severity, fire intensity, and percentage of burned area (PBA), may influence ΔT_fire through their impacts on postfire vegetation damage and, if so, there may be important feedbacks between fire regime and climate warming through biophysical effects. Here, we employ satellite observations to investigate postfire diurnal ΔT_fire across NABF. We further use a stepwise multiple linear regression model to examine the driving factors for ΔT_fire by incorporating latitude, fire regime variables, and their interactions. Our results demonstrate a pronounced asymmetry in diurnal ΔT_fire, characterized by daytime warming in contrast to nighttime cooling. Clear latitudinal patterns are found in ΔT_fire, with stronger effects in lower latitudes. Such latitudinal patterns of ΔT_fire, especially the daytime one, are driven by both latitudinal patterns in fire regimes and an increased sensitivity of ΔT_fire to fire regime as the latitude decreases. The multiple linear regression model explains 37% of the variance in daytime ΔT_fire, whereas for the nighttime ΔT_fire the explanatory power is rather low (5%). For daytime ΔT_fire, fire severity accounted for most (43.65%) of the model explanatory power, followed by PBA (24.60%) and fire intensity (13.10%). Our results highlight important fire regime impacts on daytime ΔT_fire and, further, on the annual ΔT_fire, suggesting that fire might amplify future boreal climate change through positive feedbacks between fire regime and postfire surface warming.

The extensive implementation of the ‘Grain for Green’ project over the Loess Plateau has improved environmental quality. However, it has resulted in a greater consumption of soil water, and its overall hydrological effects remain highly controversial. Our study utilized a coupled land-atmosphere model to evaluate the effects of vegetation changes resulting from revegetation or reclamation on the hydrology of the Loess Plateau. Revegetation was found to stimulate an increase in precipitation, evapotranspiration, and atmospheric water content. However, the increase in precipitation was insufficient to compensate for soil water loss driven by intensified evapotranspiration, resulting in a decrease in both runoff and soil water content. In contrast to revegetation, reclamation would reduce precipitation, although the reduction was less than the decrease in evapotranspiration. This could lead to an increase in both runoff and soil water content. The results provide an important scientific basis for the hydrological effects of vegetation changes on the Loess Plateau, which is particularly important for guiding current and future revegetation activities toward sustainable ecosystem development and water resources management.