The variation and trends of nitrogen cycling and nitrogen isotope composition in tree rings: the potential for fingerprinting climate extremes and bushfires

Abstract

Purpose Climate extremes, such as droughts and floods, have become intensified and more frequent due to intensifying climate change. Increased atmospheric carbon dioxide (CO2) and warming-induced water limitation, as well as climate extremes, may alter carbon (C) and nitrogen (N) cycling in forest ecosystems. This provides a brief review of stable nitrogen isotopic composition (δ15N) in tree ring in relation to climate extremes and bushfires in context of N availability and losses in forest ecosystems. Material and methods Tree rings were extracted from four Pinus sylvestris and four Larix gmelinii sample trees, located in a boreal plantation forest of Mohe City, Heilongjiang Province, China. Tree rings were measured to obtain mean annual basal area increment (BAI), while tree ring δ15N and total N concentrations were measured on mass spectrometer at 3-year intervals. The tree ring δ15N data were related to possible climate extremes and bushfires. A brief review of the relevant literature was also undertaken to support our preliminary research findings. Results and discussion Globally, increasing atmospheric CO2 concentration and water limitations have led to a warmer-drier climate. This has also been associated with increases of climate extremes such as drought and floods as well as bushfires. These extremes have been recorded with detrimental effects on plant and soil structures within forest ecosystems and play an important role in regulating N availability and losses in forest ecosystems. Studies of N deposition within forest ecosystems using soil and plant δ15N also showed that N losses under various climate extremes can occur through direct changes in N cycling, such as increasing soil nitrification and denitrification or leaching. It is highlighted that tree rings δ15N has the potential to fingerprint the intensity and frequency of climate extremes and bushfires in the forest ecosystems, but more such tree ring δ15N research needs to be done in diversified forest ecosystems to confirm the potential of using tree ring δ15N for quantifying the frequency and intensity of climate extremes and bushfires at both regional and global scale. Conclusion The variation and trend of δ15N in the soil–plant-climate systems are closely linked to the N cycling in forest ecosystems, and tree ring δ15N has the great potential to fingerprint both intensity and frequency of climate extremes such as drought and floods as well as bushfires.

Quantitatively mapping the research status and trends of vegetation responses to climate change with bibliometric analysis

“…Vegetation can be a sensitive indicator of climate change (Sun et al 2010;Xu et al 2014;Fu et al 2020;Succarie et al 2020Succarie et al , 2022Liu et al 2021). Changes in vegetation activity are critical for understanding the mechanisms of climate change impacts on ecosystem structure and functions (Ito and Inatomi 2012;Piao et al 2019).…”

Advances in the study of global forest wildfires

“…Forests absorb about a quarter of the carbon dioxide emitted into the atmosphere, so they play an extremely important role in buffering the Earth's contribution to the rise of carbon dioxide in the atmosphere (Anderegg et al 2022). Since 2000, research on wildfires and climate change has been increasing (Succarie et al 2022), and the effects of climate change on fire occurrence include increased temperatures and increased atmospheric CO 2 concentrations. First, warming and increased CO 2 concentrations lead to longer growing seasons, increasing forest and grassland biomass and thus surface combustible loads.…”

Effects of planting basins and farmyard manure addition on soil carbon and nitrogen pools under on‐farm conditions in Makueni county of Kenya

“…The discrimination against the heavier 15 N isotope by microbial N transformations in the soil predominantly affects soil δ 15 N (Asadyar et al., 2021; Hosseini‐Bai et al., 2015; Nessa et al., 2021; Succarie et al., 2022; Xu et al., 2008). Thus, higher δ 15 N in terrestrial ecosystems indicates active N cycling or N availability because of increased microbial activity (Asadyar et al., 2021; Hosseini‐Bai et al., 2015; Succarie et al., 2022; Wang et al., 2020). On the other hand, soil δ 13 C is a biological indicator of C cycling and could be used to interpret soil organic matter (SOM) mineralization processes and land uses (Wang et al., 2013; Saiz et al., 2016; Succarie et al., 2020; Sun et al., 2021; Liu et al., 2021; Fu et al., 2023).…”

“…Soil δ 13 C and δ 15 N are also used to understand the pathways in which C and N leave the ecosystem (Ibell et al., 2010, 2013; Reverchon et al., 2012; Wang, Wang, et al., 2015; Wang, Xu, et al., 2015; McCorkle et al., 2016; Jeong et al., 2022). The 15 N of N sources such as manure or fertilizer applied to the soil, N loss, and N cycling processes affects soil δ 15 N (Asadyar et al., 2021; Choi et al., 2017, 2020; Succarie et al., 2022; Zhang et al., 2018). The soil δ 15 N best indicates N availability or losses since it is enriched with increasing soil N losses because of leaching and denitrification (Ibell et al., 2013; Hosseini‐Bai et al., 2015; Wang et al., 2014, Wang, Wang, et al., 2015; Wang, Xu, et al., 2015; Nessa et al., 2021).…”

“…The soil δ 15 N best indicates N availability or losses since it is enriched with increasing soil N losses because of leaching and denitrification (Ibell et al., 2013; Hosseini‐Bai et al., 2015; Wang et al., 2014, Wang, Wang, et al., 2015; Wang, Xu, et al., 2015; Nessa et al., 2021). The discrimination against the heavier 15 N isotope by microbial N transformations in the soil predominantly affects soil δ 15 N (Asadyar et al., 2021; Hosseini‐Bai et al., 2015; Nessa et al., 2021; Succarie et al., 2022; Xu et al., 2008). Thus, higher δ 15 N in terrestrial ecosystems indicates active N cycling or N availability because of increased microbial activity (Asadyar et al., 2021; Hosseini‐Bai et al., 2015; Succarie et al., 2022; Wang et al., 2020).…”