Arctic Plant Responses to Summer Climates and Flooding Events: A Study of Carbon and Nitrogen‐Related Larch Growth and Ecosystem Parameters in Northeastern Siberia.

Built upon a 5‐year field investigation and a 13‐year satellite data set, this study examines the intricate interrelationships among ecophysiological parameters of Larix gmelinii trees and the prevailing ecosystem, climatic, and environmental factors present in the Indigirka lowlands of northeastern Siberia. It identified spatial‐temporal patterns in July needle nitrogen (N) content as an indicator of N availability from 2009 to 2013. Needle N content (%) revealed distinct yearly values: 2012 (1.31 ± 0.24), 2013 (1.67 ± 0.39), 2009 (1.72 ± 0.15), 2011 (1.84 ± 0.34), and 2010 (2.08 ± 0.25). Positive correlations were found between ecosystem and larch parameters, as well as between September temperature or February/May precipitation and subsequent July ecosystem productivity. Soil moisture (SM) primarily influences N availability across sites, with higher SM levels reducing N availability. However, July air temperature (AT) is the primary driver of interannual N availability changes, with higher temperatures enhancing N availability. Larch photosynthesis is mainly influenced by solar radiation (SR), temperature, N availability, and SM. Annual fluctuations in SR positively impact larch photosynthesis, while high temperatures or wetting events impose limitations on photosynthesis, even if N availability has increased. Consequently, a moderate correlation exists between N availability and photosynthesis across various sites and years (r = 0.422, P = 0.133, n = 14). In summary, this research provides valuable insights into climatic and environmental impacts on larch trees and ecosystems, emphasizing the significance of SM, AT, and SR for predicting future growth patterns of larch. Plain Language Summary: This study investigated nitrogen (N) and carbon (C) levels in July for larch trees growing in the Arctic lowlands of northeastern Siberia. We achieved this by conducting a 5‐year field observation from 2009 to 2013, supplemented with a 13‐year analysis of satellite data. This allowed us to investigate how climate and environmental factors influence these trees. Larch N levels varied depending on the location and year, and soil moisture (SM) and air temperature (AT) playing crucial roles. Wet conditions increase SM and then limit larch N levels, while warmer temperatures enhance N levels. Larch photosynthesis is influenced by sunlight, AT, N levels, and SM. More sunlight improves photosynthesis, but much warmer temperatures or very wet conditions can limit photosynthesis, even if there is enough N. Interestingly, larch photosynthesis and ecosystem productivity showed similar year‐to‐year patterns. Decadal analysis highlights how winter conditions are really important in shaping ecosystem productivity during future Julys. Aside from summer conditions, winter conditions may also exert some influence on larch photosynthesis. This study improves our understanding of N and C levels in summer larch trees, emphasizing the significance of climate and environment in their growth and productivity. Key Points: For larch nitrogen availability in July, soil moisture (SM) controls spatial variations, while air temperature governs interannual fluctuationsFor larch photosynthesis in July, SM shapes spatial variations, while solar radiation and temperature impact interannual changesElevated September air temperatures or increased February/May precipitation will enhance ecosystem productivity in the upcoming July [ABSTRACT FROM AUTHOR]