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Climate change has far-reaching impacts on ecosystems and the frequency and intensity of extreme global climate events have been increasing over the past century; therefore, assessing ecosystem vulnerability to extreme climate change is critical for sustainable and adaptive ecosystem management. As a climatically sensitive region, coastal China is currently experiencing significant environmental changes. To identify how extreme climate affects ecosystem vulnerability, we calculated and analyzed the spatiotemporal variation in extreme climates, net primary productivity (NPP), and spatial characteristics of ecosystem vulnerability to extreme climate change, and discussed the response characteristics of different ecosystems to extreme climate events based on meteorological data and NPP (1986–2015). The results demonstrated that (1) coastal China has become increasingly warmer over the last thirty decades but the precipitation trend is different in the north and south: precipitation increased in the south and decreased in the north. (2) NPP is rising overall, with the forest ecosystem growing the fastest, particularly since 2010. (3) The ecosystem vulnerability of coastal areas in China is mainly classified as mild or non-vulnerable. However, there were apparent differences in the vulnerability of different ecosystems, with dry land and shrub ecosystems having the highest mean vulnerability. (4) The effects of extreme climates on the vulnerability of different ecosystems and ecosystems in different habitats vary. Overall, rising extreme temperatures can significantly increase the ecosystem vulnerability in the coastal areas of China. The paddy field ecosystem was more influenced by extreme temperatures than other ecosystems, with the southern paddy field ecosystem more influenced than the northern paddy field ecosystem. Our study advances the understanding of vegetation dynamics and their driving mechanisms and provides support for scientifically informed ecological management practices in coastal China.

The establishment of structure activity relationship (SAR) for rakicidin derivatives is pretty vital to develop rakicidins as a new type of anti-cancer agents. Herein, two novel rakicidin derivatives, compounds B1-1 (1) and B1-2 (2), a cyclic depsipeptide and a chain lipopeptide, respectively, were isolated from culture broth of Micromonospora chalcea FIM-R160609, and their structures were elucidated clearly by extensive NMR and HR-ESI-MS analyses. Following, their cytotoxic activities were evaluated against HCT-8 and PANC-1 human cancer cell lines under hypoxic and normoxic conditions. Their activities were significantly decreased when compared with that of rakicidin B1. These results demonstrated that the double bond located on the position 9 and 10 of conjugated diene unit and cycle-type structure plays an important role in keeping the biological activity of rakicidins. Furthermore, the positive effect of double bond and cycle form on the anti-bacterial activities were also confirmed by testing their inhibitory activities against gram positive bacteria. This work will definitely diversify the SAR of rakicidins and provide the guidance for the design of new potent rakicidin analogues. [ABSTRACT FROM AUTHOR]

The escalating frequency and severity of extreme climate greatly impact the carbon dynamics of terrestrial ecosystems worldwide. To understand the multi-temporal response of net ecosystem productivity (NEP) to extreme climate, we investigated 11 temperature and precipitation extreme indices across different vegetation types in China. From 1981 to 2019, the results showed that NEP in China increased at a rate of 0.64 g·m−2·a−2. Extreme climate demonstrated a significant warming trend and a non-significant moistening trend; specifically, maximum daily minimum temperature (TNx) exhibited a significant increase at a rate of 0.34 °C/10 a, while maximum 5-day precipitation (Rx5day) showed an insignificant increase at a rate of 1.78 mm/10 a. NEP was significantly impacted by extreme temperature at the annual, seasonal, and monthly scales, but moderately impacted by extreme precipitation. Specifically, extreme temperature had the most significant effect on grassland, with minimal influence on cropland. In contrast, extreme precipitation had the most significant effect on forest, with minimal impact on cropland. Moreover, the lagged time for extreme precipitation was longer than that for extreme temperature. Extreme precipitation exhibited a corresponding lagged time of at least 2 months (p < 0.01), while extreme temperature exhibited a lagged time of at least 1 month (p < 0.01). The maximum lag time observed was 4 months (p < 0.01). Our findings provide valuable insights into the multi-temporal response of NEP to extreme climate in China and inform sustainable development practices in the region. [ABSTRACT FROM AUTHOR]