The spatial variation of forest aboveground carbon sequestration (ACS) is crucial for assessing the carbon storage and time of carbon-emission peaking. Unfortunately, a systematic assessment of accurate ACS and its change has not yet been developed, especially at a large scale. Here, we evaluate the spatiotemporal ACS trend based on LANDIS PRO and PnET-II models from 2000 to 2020 in Western Sichuan, China, coupled with multi-source remote sensing datasets (e.g., MODIS and Lansat) and in situ forest inventory to obtain the landscape information. The Mann-Kendall trend test is used to examine the ACS trend. The total ACS increased from 344.62 to 466.99 Tg due to large-scale reforestation programs from 2000 to 2020. The evergreen coniferous forest contributed the most ACS (85.28%) in Western Sichuan compared with other species. The developed methodology can be applied to analyzing the ACS at the watershed and regional levels promptly and helping decision-makers and managers develop effective forest management measures.

Recently studies usually used remote sensing products and reanalysis datasets to obtain the precipitation. Yet, due to sparse ground observations and complex topography, the accuracy of precipitation products in mountainous regions is one of the great concerns in hydrology. Thus, assessing the accuracy and availability of precipitation products is vital to hydrological research in mountainous regions. In this study, we evaluated the precision of precipitation products including IMERG, ERA5-Land, and AERA5-Asia at multiple temporal and spatial scales using ground observations of meteorological stations from 2001 to 2015 in Southwest China, a typical mountainous region. The key findings are: (1) The IMERG datasets had the best performance on a monthly scale. (2) The IMERG and AERA5-Asia data products had higher precision at seasonal and annual scales. (3) The AERA5-Asia achieved better performance in the high- altitude areas compared to others. In addition, the ERA5- Land has the lowest accuracy. This study can provide important guidelines for the selection of precipitation products for both scientific and management purposes in mountainous areas, especially in Southwest China.

Climate variability and vegetation disturbance as critical driving factors significantly affect the regional hydrology in forested watersheds. Yet, due to landscape heterogeneities such as topography, soil characteristics, climate conditions, and vegetation types, hydrological responses to climate and forest changes and associated mechanisms have not been fully understood. The forested Stellako watershed, a typical forest-disturbed area in Canada, has been studied to assess the annual streamflow affected by climate variability and forest disturbance. The study period was from 1951 to 2018. The methods include the modified double mass curve (MDMC), Autoregressive Integrated Moving Average (ARIMA) intervention, and multivariate ARIMA. In the Stellako watershed, 1980 was identified as a breakpoint in the yearly time series between 1951 and 2018. The 1951-1979 period was considered the reference. From 1980 to 2018, the streamflow decreased by 14.69 and 26.18 mm due to climate and forest changes, respectively. The annual runoff variation was mainly attributed to forest disturbances contributing 60.78% of the total variations. Thus, a timely assessment of the runoff variety at a watershed scale has been obtained. The developed methodology can be applied to quantify the disturbance effects at a watershed or regional scale and develop watershed and forest management strategies under future climate and forest changes.

Understanding the temporal variations of terrestrial water storage (TWS) in large river basins is crucial for water resource management and ecosystem protection. Yet, the variations of TWS in large river basins are often been assessed in term of temporal trends with limited studies on the stationarity of TWS. In this study, we investigated the temporal trends and stability of TWS in then large river basins in China from 2004 to 2014 using the corrected Gravity Recovery and Climate Experiment (GRACE) gravity satellite data. Key findings are: (1) the average TWS in China showed a significant downward trend during the study period; and (2) the TWS in ten large river basins was non-stationary across China. Water surpluses were observed in the Northeast and the Southeast, while water deficits were found in the Northwest and the Southwest. This study provides policy-makers with critical information to design adaptive strategies and plans for basin-scale water resources management.

Southwest China is an ecologically fragile area in China. Understanding temporal and spatial variations of vegetation degradation can help to formulate measures of ecosystem protection and ecological function restoration. In this study, we evaluated vegetation dynamics and identified vegetation degradation and its spatial patterns in Southwest China, based on land cover, DEM, and GLASS LAI datasets from 2001 to 2017. The key results are: (1) Though the average LAI in Southwest China showed an insignificant trend during the study period, based on grid-scale analysis, significant declines in LAI indicating vegetation degradation were identified in some areas such as western Sichuan, western and central Yunnan, and western Tibet; (2) about 10.75% of the vegetation experienced significant degradation during the study period in Southwest China; (3) degraded vegetation was mostly distributed in high elevation areas, and about 43% degraded vegetation was located in areas with the elevation between 3500m and 5000m; (4) the dominant degraded vegetation types included grassland, alpine vegetation, shrubland, and coniferous forest. Our findings can provide valuable management implications for vegetation restoration and ecological protection in Southwest China.

The upper Minjiang River watershed provides critical ecological services to sustain downstream populated cities in the Chengdu plain of China. Understanding its environmental quality dynamics and associated response to vegetation change can help with vegetation restoration program designs for better protection of watershed ecosystems. In this study, five environmental quality indices were first calculated to evaluate environmental quality dynamics by use of MODIS MCD12Q1 and SPOT NDVI products. Then, responses of environment quality to vegetation change from 2001 to 2017 were assessed. Key findings were: (1) there was a slight decline in the integrated ecological index (EI), indicating a relatively stable environment quality in the study watershed; (2) EI had significant positive correlations with forest land or grassland area, while its relationship with the sparse woodland area was significantly negative; and (3) environmental quality changes were mainly driven by soil erosion, earthquake, landslides, vegetation change, and human activities. This study has important implications for the protection of environmental quality by vegetation restoration.