• Energy Research

AbstractA key challenge in ecology is to understand the relationships between organismal traits and ecosystem processes. Here, with a novel dataset of leaf length and width for 10 480 woody dicots in China and 2374 in North America, we show that the variation in community mean leaf size is highly correlated with the variation in climate and ecosystem primary productivity, independent of plant life form. These relationships likely reflect how natural selection modifies leaf size across varying climates in conjunction with how climate influences canopy total leaf area. We find that the leaf size‒primary productivity functions based on the Chinese dataset can predict productivity in North America and vice‐versa. In addition to advancing understanding of the relationship between a climate‐driven trait and ecosystem functioning, our findings suggest that leaf size can also be a promising tool in palaeoecology for scaling from fossil leaves to palaeo‐primary productivity of woody ecosystems.

AbstractA key challenge in ecology is to understand the relationships between organismal traits and ecosystem processes. Here, with a novel dataset of leaf length and width for 10 480 woody dicots in China and 2374 in North America, we show that the variation in community mean leaf size is highly correlated with the variation in climate and ecosystem primary productivity, independent of plant life form. These relationships likely reflect how natural selection modifies leaf size across varying climates in conjunction with how climate influences canopy total leaf area. We find that the leaf size‒primary productivity functions based on the Chinese dataset can predict productivity in North America and vice‐versa. In addition to advancing understanding of the relationship between a climate‐driven trait and ecosystem functioning, our findings suggest that leaf size can also be a promising tool in palaeoecology for scaling from fossil leaves to palaeo‐primary productivity of woody ecosystems.

The UK Government is hosting COP26 in Glasgow between 31st October and 12th November 2021. It plans to make progress in four key areas which summarize as ‘coal, cars, cash and trees’ (Carbon Brief, 2021). The first two of these aims—to get agreement for the rapid phase out of coal, the most polluting of fossil fuels, and to ensure a rapid transition away for cars fuelled by fossil fuels—are very important, but are not directly related to the remit of Global Change Biology. The latter two aims—ensuring that the financial support of $100 billion per year promised in 2010 by wealthy countries to developing countries finally gets delivered and ensuring that climate solutions adopted also co-deliver to nature—are squarely within the remit of Global Change Biology. With respect to the ‘cash’ aim, this flow of finance is essential to allow poorer countries to adapt to, and to mitigate, climate change. We know that a vast proportion of the potential for natural climate solutions is located in the developing world (Griscom et al., 2020), so if we are to realize that global potential, developing countries must have the financial backing to ensure that this happens in an equitable and just way. Not all of this cash will be used for nature-based solutions, of course, but a proportion of it will be, and nature-based solutions would almost certainly not happen at the scale and speed required to help us meet net zero greenhouse gas emissions targets without this cash. With respect to the ‘trees’ aim, the first thing to note is that nature-based solutions are about so much more than just planting trees (Seddon et al., 2021)! ‘Trees’ is just shorthand for nature-based solutions, but the broad variety of nature-based solutions available, beyond just tree planting, must be encouraged at COP26. The recent joint workshop report by IPBES and IPCC (Pörtner et al., 2021) demonstrated that we cannot successfully resolve either of the existential threats of climate change or biodiversity loss unless we tackle ...

The UK Government is hosting COP26 in Glasgow between 31st October and 12th November 2021. It plans to make progress in four key areas which summarize as ‘coal, cars, cash and trees’ (Carbon Brief, 2021). The first two of these aims—to get agreement for the rapid phase out of coal, the most polluting of fossil fuels, and to ensure a rapid transition away for cars fuelled by fossil fuels—are very important, but are not directly related to the remit of Global Change Biology. The latter two aims—ensuring that the financial support of $100 billion per year promised in 2010 by wealthy countries to developing countries finally gets delivered and ensuring that climate solutions adopted also co-deliver to nature—are squarely within the remit of Global Change Biology. With respect to the ‘cash’ aim, this flow of finance is essential to allow poorer countries to adapt to, and to mitigate, climate change. We know that a vast proportion of the potential for natural climate solutions is located in the developing world (Griscom et al., 2020), so if we are to realize that global potential, developing countries must have the financial backing to ensure that this happens in an equitable and just way. Not all of this cash will be used for nature-based solutions, of course, but a proportion of it will be, and nature-based solutions would almost certainly not happen at the scale and speed required to help us meet net zero greenhouse gas emissions targets without this cash. With respect to the ‘trees’ aim, the first thing to note is that nature-based solutions are about so much more than just planting trees (Seddon et al., 2021)! ‘Trees’ is just shorthand for nature-based solutions, but the broad variety of nature-based solutions available, beyond just tree planting, must be encouraged at COP26. The recent joint workshop report by IPBES and IPCC (Pörtner et al., 2021) demonstrated that we cannot successfully resolve either of the existential threats of climate change or biodiversity loss unless we tackle ...

Soil organic matter (SOM) is one of the most complex natural mixtures on earth. It plays a critical role in many ecosystem functions and is directly responsible for sustaining life on our planet. However, due to its chemical heterogeneity, SOM composition at molecular-level is still not completely clear. Consequently, the response of SOM to global climate change is difficult to predict. Here we highlight applications of two complementary molecular-level methods (biomarkers and nuclear magnetic resonance (NMR)) for ascertaining SOM responses to various environmental changes. Biomarker methods that measure highly specific molecules determine the source and decomposition stage of SOM components. However, biomarkers only make up a small fraction of SOM components because much of SOM is non-extractable. By comparison, (13)C solid-state NMR allows measurement of SOM in its entirety with little or no pretreatment but suffers from poor resolution (due to overlapping of SOM components) and insensitivity, and thus subtle changes in SOM composition may not always be detected. Alternatively, (1)H solution-state NMR methods offer an added benefit of improved resolution and sensitivity but can only analyze SOM components that are fully soluble (humic type molecules) in an NMR compatible solvent. We discuss how these complementary methods have been employed to monitor SOM responses to: soil warming in a temperate forest, elevated atmospheric CO(2) and nitrogen fertilization in a temperate forest, and permafrost thawing in the Canadian High Arctic. These molecular-level methods allow some novel and important observations of soil dynamics and ecosystem function in a changing climate.

Soil organic matter (SOM) is one of the most complex natural mixtures on earth. It plays a critical role in many ecosystem functions and is directly responsible for sustaining life on our planet. However, due to its chemical heterogeneity, SOM composition at molecular-level is still not completely clear. Consequently, the response of SOM to global climate change is difficult to predict. Here we highlight applications of two complementary molecular-level methods (biomarkers and nuclear magnetic resonance (NMR)) for ascertaining SOM responses to various environmental changes. Biomarker methods that measure highly specific molecules determine the source and decomposition stage of SOM components. However, biomarkers only make up a small fraction of SOM components because much of SOM is non-extractable. By comparison, (13)C solid-state NMR allows measurement of SOM in its entirety with little or no pretreatment but suffers from poor resolution (due to overlapping of SOM components) and insensitivity, and thus subtle changes in SOM composition may not always be detected. Alternatively, (1)H solution-state NMR methods offer an added benefit of improved resolution and sensitivity but can only analyze SOM components that are fully soluble (humic type molecules) in an NMR compatible solvent. We discuss how these complementary methods have been employed to monitor SOM responses to: soil warming in a temperate forest, elevated atmospheric CO(2) and nitrogen fertilization in a temperate forest, and permafrost thawing in the Canadian High Arctic. These molecular-level methods allow some novel and important observations of soil dynamics and ecosystem function in a changing climate.

ABSTRACTSoil organic carbon (SOC) decomposition underpins soil‐atmosphere carbon exchange and is regulated by climate change‐mediated variations in soil redox conditions. Periodic anoxia, commonly occurring following precipitation, soil flooding, and erosion events, is assumed to preserve SOC. Yet, water saturation may also increase SOC decomposition relative to unsaturated conditions, and contradictory findings among previous studies remain unexplained. Here, using incubation experiments on 20 soils collected across a 24° latitude gradient in China, we show that 70% of the soils showed a higher or similar anoxic decomposition rate of SOC compared to the oxic treatment, indicating fast SOC loss under relatively short anoxia. Methane production was far lower than CO2 due to the presence of alternative terminal electron acceptors (TEAs). Variation in alternative TEAs and microbial community shows that fast anoxic decomposition was primarily driven by iron (Fe) reduction, which accounted for up to 90% of anoxic CO2 production. Meanwhile, positive relationships among water‐extractable organic carbon (OC), hydrochloric acid‐extractable ferrous Fe, relative abundance of Fe‐reducing prokaryotes, and the SOC decomposition rate suggest the release of readily metabolized substrates following Fe reduction. This release provided substrates for anoxic metabolism and potentially led to the loss of OC protected by Fe (Fe‐bound OC; a slow‐cycling OC pool under oxic conditions). Mass balance calculation confirms that Fe‐bound OC loss was mostly similar to elevated anoxic SOC decomposition in magnitude, and random forest modeling indicates that soils rich in reducible Fe, SOC, and Fe‐reducing prokaryotes most likely experience elevated SOC decomposition under periodic anoxia. Overall, our findings demonstrate that fast anoxic decomposition of SOC is a potentially important pathway that may stimulate SOC loss under climate change‐mediated intense hydrologic regimes, particularly for soils rich in reducible Fe and SOC.