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Future crop yield increases are unlikely to keep pace with the dietary needs of a global human population expected to reach nine billion by 2050. This study used United States Department of Agriculture county‐level yield data and autoregressive moving‐average models to examine how changes in maize (Zea maysL.), soybean (Glycine maxL.), and winter wheat (Triticum aestivumL.) yields, temporal variability in yields, and yield gaps have varied across space and time from 1970–2017. The majority of county‐level yields have increased linearly, although the increases in wheat lag behind corn and soybean. Where trends were nonlinear, accelerating yields were found in more mesic regions east of the Great Plains, and decelerating yields were found in the drier central and western United States. Mean crop yields were positively correlated with rate of yield increase and negatively correlated with interannual variability. Hotspots were identified in Minnesota, Iowa, Illinois, Nebraska, and some West Coast states where crop yields are currently the largest, have the lowest yield gaps, and since 1970, have had the highest rates of change and/or are experiencing an acceleration of annual yield gains. Across all crop types, the counties with the lowest average yields, highest yield gaps, lowest rates of yield increase over time, and/or deceleration in yield increases were predominantly found in the central United States, including the Dakotas, Kansas, Oklahoma, and Texas. Regions of greatest performance generally have fertile soils, plentiful growing season rainfall, and optimal growing season length and temperatures, or are benefitting from irrigation.

Paleoclimate records identified a severe drought lasting approximately a decade on the Mongolian Plateau during the 2000s, the severity of which was only exceeded by a single drought during the last two millennia. Under high‐emission scenarios, arid and semiarid areas are projected to continue to experience a drying trend over the coming decades; therefore, understanding how ecosystems respond to long‐lasting drought has global implications. Here we used a process‐based ecosystem model to examine the interannual and intra‐annual variations in net ecosystem productivity in response to climate extremes across the Mongolian Plateau. We find that the recent‐decade drought caused Mongolian terrestrial ecosystems to shift from a carbon (C) sink to a C source, canceling 40% of climate‐induced C accumulation over the entire twentieth century. Our study details a shortened C sequestering season, increased summer C source, and accelerated C depletion during the 2000s drought. Multiple lines of evidence have shown detrimental effects of drought events on ecosystem production and carbon dynamics, but it remains uncertain how arid and semiarid ecosystems respond to long‐lasting drought. Here we reveal that a severe drought during the first decade of the 2000s on the Mongolian Plateau considerably weakened C sequestration capacity and accelerated C depletion. This work has broad implications for understanding impacts of persistent droughts on terrestrial C dynamics as a drying trend, in many arid and semiarid areas, is projected to continue over the coming decades. The recent decade (2000–2009) has been identified as one of the driest periods on the Mongolian Plateau over the most recent ~2,000 yearsThis long‐duration drought shortened the C sequestration season, increased the summer C source, and led to a net annual C releaseThe NEP amplitude in this dry decade increased due to reduced C uptake and increased C emissions, implying an accelerated C depletion

Pasture can be either a source or a sink for atmospheric carbon dioxide, depending primarily on climate and land management. In the absence of specific data on pasture in the northeastern United States, the parameterization of ecosystem models for carbon and energy flux has been based on data from grasslands in the Great Plains (United States), where climate is more arid and less management intensive than in the eastern United States. Models have not been adequately parameterized to simulate carbon dynamics under managed dairy grasslands in the humid eastern United States. This paper aims to provide TEM‐Hydro2—a terrestrial ecosystems model—with region‐specific dairy pasture parameterization in Pennsylvania to more realistically determine humid grassland dynamics under a changing climate. Through this study, we highlight the importance of considering region‐specific calibration data in reporting realistic ecosystem response to climate change through the comparison to a simulation based on a xeric parameterization. Our field observations indicate that Pennsylvania's more humid climate results in higher carbon and nitrogen flux exchanges between grassland and the atmosphere, but the soil carbon pool is significantly lower compared with the semiarid grassland. Moreover, Pennsylvania pasture is simulated to be more sensitive to climate change based on the region‐specific parameterization. Projected to the end of the 21st century, dairy pasture in Pennsylvania will probably experience increased carbon uptake and soil carbon accumulation under continuous grazing management, while hay production would drastically reduce Pennsylvania dairy pasture's capacity to sequester carbon.

One of the most largest known and important metallogenic provinces in China is East Tianshan, where seven major types of Late Paleozoic metal deposits have been recognized: (1) porphyry-type Cu-Mo-(Au) ore deposits, (2) volcanic Fe-Cu deposits, (3) orogenic lode gold deposits, (4) magmatic Cu-Ni sulfide deposits, (5) epithermal gold deposits, (6) volcanic hydrothermal Cu deposits, and (7) skarn Cu-Ag deposits. Tectonically, the development of these Late Paleozoic metal mineral deposits was closely associated with the subduction and closure of the ancient Tianshan ocean intervening between the Tarim craton and the Junggar-Kazakhstan block. In the Late Devonian to Early Carboniferous, the northern margin of the Tarim craton existed as a passive-type continental margin, whereas the ancient Tianshan ocean was subducted beneath the southern margin of the Junggar-Kazakhstan block, resulting in the formation of the Dananhu-Tousuquan magmatic arc and associated porphyry-type Cu-Mo-(Au) deposits. In the Middle Carboniferous, the ancient Tianshan ocean began to subduct beneath the northern margin of the Tarim craton, leading to the formation of the Aqishan-Yamansu magmatic arc and associated volcanic Fe-Cu deposits. In the Late Carboniferous, the ancient Tianshan ocean was closed, and a continent-arc collision occurred, leading to the formation of the Tianshan orogen. Following the collision was an extensional event, which was associated with the emplacement of large amounts of ultramafic-mafic complexes and the formation of a number of large- to medium-scale magmatic copper-nickel ore deposits along the Kangger suture zone. In the Early Permian, East Tianshan entered into a post-collision stage, associated with the widespread emplacement of granitoid bodies and eruption of within-plate volcanism, which led to the formation of volcanic hydrothermal copper deposits, skarn-type Cu-Ag deposits, post-orogenic gold deposits, and epithermal gold deposits in East Tianshan.

Spatiotemporal patterns of crop nitrogen (N) budget have important implications for agricultural N management and environmental policy. Previous studies examined crop N budget in different countries but often overlooked cross‐crop differences at sub‐national scales. In this study, we synthesize multiple databases to examine the N budget of eight major crops in the United States at the county scale during 1970–2019. Our analyses show that national crop N use efficiency (NUE) increased from 0.55 kg N kg−1N in the 1970s to 0.65 kg N kg−1N in the 2010s. Four out of eight crops such as corn, rice, cotton, and sorghum demonstrated an increasing NUE trend during the study period, whereas the other crops overall presented a declining NUE trend. Nationwide, about 41% of the total N input was not used by these crops (i.e., N surplus) over the study period, of which temporal variation was mainly driven by corn due to its large planting area and high N input. The national N surplus first increased in the 1970s and remained relatively stable till the 2000s. Since the early 2010s, however, N surplus began to decline and approached the levels in the early 1970s—an encouraging development that may lead to decreased N pollution to the environment. The hotspots of national N surplus coincided with corn‐ and rice‐producing counties. The sub‐national variations and temporal dynamics in crop N budget revealed in this study highlight the urgent need to understand the farm‐level crop N balance and the dominant factors controlling crop NUE for mitigating N pollution. We synthesized county‐level crop nitrogen (N) budget data of eight major crops in the United States during 1970–2019The national crop nitrogen use efficiency (NUE) increased from 0.55 kg N kg−1N in the 1970s to 0.65 kg N kg−1N in the 2010s, with an average NUE of 0.59 kg N kg−1NN surplus accounted for 41% (27%–55%) of the national total N input, with a significant decline detected during the recent decade We synthesized county‐level crop nitrogen (N) budget data of eight major crops in the United States during 1970–2019 The national crop nitrogen use efficiency (NUE) increased from 0.55 kg N kg−1N in the 1970s to 0.65 kg N kg−1N in the 2010s, with an average NUE of 0.59 kg N kg−1N N surplus accounted for 41% (27%–55%) of the national total N input, with a significant decline detected during the recent decade