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Concentrations of leaf nitrogen (N) and phosphorus (P) are key leaf traits in ecosystem functioning and dynamics. Foliar stoichiometry varies remarkably among life forms. However, previous studies have focused on trees and grasses, leaving the knowledge gap for the stoichiometric patterns of shrubs. In this study, we explored the intra- and interspecific variations of leaf N and P concentration in relation to climate, soil property and evolutionary history based on 1486 samples composed of 163 shrub species from 361 shrubland sites in northern China expanding 46.1° (86.7-132.8° E) in longitude and 19.8° (32.6-52.4° N) in latitude. The results showed that leaf N concentration decreased with precipitation, leaf P concentration decreased with temperature and increased with precipitation and soil P concentration. Both leaf N and P concentrations were phylogenetically conserved, but leaf P concentration was less conserved than leaf N concentration. At community level, climates explained more interspecific, while soil nutrient explained more intraspecific, variation of leaf nutrient concentrations. These results suggested that leaf N and P concentrations responded to climate, soil, and phylogeny in different ways. Climate influenced the community chemical traits through the shift in species composition, whereas soil directly influenced the community chemical traits. [ABSTRACT FROM AUTHOR]

Given the interdependence of climate change (CLC) and urban expansion (URE) on ecosystem productivity in China and India, hybrid physics-based models were fitted in this study to evaluate the effects of these variables on photosynthetically active radiation (PAR). This was accomplished by interpolating the most recent five general circulation models (GCMs) from coupled model intercomparison project phase 6 (CMIP6) into the CMIP6 multi-ensemble model. The potential of PAR is projected to increase by 0.001 to 2.077% in China and by 0.002 to 6.737% in India, on a seasonal and annual basis, if the warming is kept at 1.5 °C from now until the end of this century. The effects of CLC and URE on the changes in PAR in China and India were investigated, and URE had a greater impact than CLC when compared to effective contributions, with 49.47% for China and 28.41% for India in the entire case scenario. In contrast, CLC and PAR residual factor (PRF) have a greater impact in India than in China, with effects of 13.79% and 57.79% compared to 0.89% and 49.64%, respectively. Preferences for exotic, high-productivity plant species, irrigation, CO2 fertilization, and nitrogen deposition are suggested as measures for replenishing PAR in both countries. [ABSTRACT FROM AUTHOR]

[Display omitted] • Grassland degradation is the main reason for the decline in carbon storage. • The carbon storage of farmland has increased significantly. • The risk of carbon storage reduction in the future is still high. The carbon storage of terrestrial ecosystems is closely related to global climate change. Therefore, assessing the impact of land-use changes on carbon storage is instructive to reduce global carbon emissions. Taking an arid region in northwest China as an example, this paper analyzed the land-use changes in arid region from 1980 to 2015. It used the CA-Markov model to predict the land-use pattern from 2020 to 2050, the carbon storage and sequestration module in Integrated Valuation of Ecosystem Services and Tradeoffs (Invest) mode to assess and predict ecosystem carbon storage over the past 35 years and in the next 30 years and discusses the impact of land-use changes on the carbon storage of terrestrial ecosystems. The results showed that: (1) The high-value areas of carbon storage in arid region were primarily concentrated in grassland, forests and farmland, and the low-value areas of carbon storage were mainly in desert areas. (2) The carbon storage in arid region showed a downward trend. From 1980 to 2015, the carbon reserves of terrestrial ecosystems in arid region decreased by 90.95 Tg, and the net loss of carbon reserves from 2020 to 2050 was 14.72 Tg. Grassland degradation was the main reason for the reduction of carbon storage in arid region. (3) The carbon storage of farmland had increased significantly, but the expansion of farmland dominated by high carbon density grassland, wetland and forest, had reduced the overall carbon storage of the arid region. [ABSTRACT FROM AUTHOR]

Much of our existing knowledge of Middle Jurassic paleoclimate is based on well-dated marine isotopic records that show fluctuations between warm (greenhouse effected) and cool climates. In contrast, much less is known from contemporaneous terrestrial deposits that are often difficult to correlate stratigraphically with marine successions, and are typically considered as showing regional rather than global signals. In this paper we show that the carbon-isotopic, petrological and floral record through 20 m thick coals in the Northern Qaidam Basin (NW, China) represents a relatively comprehensive northern hemisphere Bajocian (Middle Jurassic) record for terrestrial climatic change. δ13C coal values for 88 samples from the Yuqia area in Northern Qaidam Basin range from–25.3‰ to –22.5‰, indicating that C3 plants were the main coal-forming vegetation in the region during the Middle Jurassic. This isotopic variation follows fluctuations in the composition of ferns and gymnosperms, where higher ratios correspond to more negative δ13C values. The similar carbon isotope values of gymnosperms and coal from the Yuqia area indicate that the coal comprises a high proportion of organic material derived from gymnosperm taxa, which is consistent with the very high abundance of diterpenoids in coal and especially pimarane and abietane that are produced primarily by gymnosperms. Results from the coal matrix provide an opportunity to record paleoclimate changes, showing several striking and regular coal-forming cycles with distinct long- and short-term variations. Trends of δ13C coal values changes coupled with the evolution of coal-forming plants may record a gradual increase in paleo-CO 2 (p CO 2) concentration, water-table level changes and the decrease in abundance of Classopollis conifer pollen through Bajocian. This result is in accordance with the published marine carbonate records for this time, with correlation enabled through matching carbon isotope curves from the terrestrial succession at Yuqia and marine records. The similarity of the terrestrial and marine geochemical and floral record is an indication that the observed paleoclimate signal is a global phenomenon. Furthermore, the high-frequency fluctuation of δ13C coal values, along with the coal petrologic variations may record short-term changes of environmental factors (e.g. temperature or humidity/precipitation), especially during intervals when palaeobotanical composition has not fluctuated intensely. • Paleoclimate trends evaluated from terrestrial Northern Qaidam Basin, NW China • Carbon-isotope, petrological and floral record of Bajocian age Yuqia coals revealed • Isotope value distribution indicate coals largely derived from gymnosperm plants • Variations in long- and short- peat deposition cycles record paleoclimate trends • Similarity of marine geochemical and terrestrial record supports global signal [ABSTRACT FROM AUTHOR]

The spatial and temporal variations of the vegetation carbon flux in China from 1901 to 2005 were studied using the vegetation net primary production (NPP) values from seven Earth-system models. In addition, the temporal and spatial changes in the nitrogen deposition flux in China were studied using the NHx and NOx fluxes from 1901 to 2005. The relationship between changes in the carbon flux, nitrogen flux and climate was analyzed. The results show that (1) over the past 100 years, NPP in China has shown an upward trend. The average trend coefficient is 0.88 and the NPP distribution trend is generally low in the north and high in the south, with a gradual increase from the northwest to the southeast. Temperature, precipitation and radiation are all conducive to plant growth in the direction of the gradient. The correlation coefficients between the ensemble model mean NPP and temperature, precipitation, longwave radiation and shortwave radiation are 0.88,0.73,0.91 and 0.67, respectively. (2) In the past 100 years, the NHx and NOy fluxes in China have shown an upward trend, with trend coefficients of 0.98 and 0.98, respectively, which pass the 99.9% confidence level of the t-test. NHx and NOy fluxes are also generally low in the north and high in the south, with a gradual increase from the northwest to the southeast in a step-like pattern. (3) The spatial distribution of the correlation coefficients between the NHx and NOy fluxes and air temperature is similar, with only slight differences in values. The spatial distribution of the correlation coefficients between the NHx and NOy fluxes and precipitation is similar in overall pattern, but the pattern is relatively complicated, with a positive-negative-positive-negative-positive pattern occurring across the monsoon region from north to south, and a negative-positive-negative-positive pattern occurring beyond the monsoon region from east to west. (4) The spatial distribution of the correlation coefficients between the NHx and NOy fluxes and NPP shows a generally consistent pattern, but the pattern is relatively uneven. The average distribution of the ensemble model mean is positive correlation in northeast China and southwest China, and alternating positive and negative correlation in other regions. [ABSTRACT FROM AUTHOR]