Abstract
Climate warming is becoming an increasingly serious threat. Understanding plant stoichiometry changes under climate warming is crucial for predicting the effects of future warming on terrestrial ecosystem productivity. Nevertheless, how plant stoichiometry responds to warming when interannual rainfall variation is considered, remains poorly understood. We performed a field soil warming experiment (+5°C) using buried heating cables in subtropical areas of China from 2015 to 2018. Stoichiometric patterns of foliar C:N:P:K:Ca:Mg, non-structural carbohydrate, and stable isotope of Cunninghamia lanceolata seedlings were studied. Our results showed that soil warming decreased foliar P and K concentrations, C:Ca, P:Ca, and P:Mg ratios. However, soil warming increased foliar Ca concentration, δ15N value, C:P and N:P ratios. The response ratios of foliar N, C:N, and δ15N to soil warming were correlated with rainfall. Our findings indicate that there was non-homeostasis of N and C:N under warming conditions. Three possible reasons for this result are considered and include interannual variations in rainfall, increased loss of N, and N limitation in leaves. Piecewise structural equation models showed that stoichiometric non-homeostasis indirectly affected the growth of C. lanceolata seedlings in response to soil warming. Consequently, the growth of C. lanceolata seedlings remained unchanged under the warming treatment. Taken together, our results advance the understanding of how altered foliar stoichiometry relates to changes in plant growth in response to climate warming. Our results emphasize the importance of rainfall variations for modulating the responses of plant chemical properties to warming. This study provides a useful method for predicting the effects of climate warming on economically important timber species.
Highlights
The global average temperature has reportedly increased by 0.85◦C compared with the pre-industrial levels (IPCC, 2018), and this has raised widespread attention
We focused on two questions: (i) how does warming affect the stoichiometric patterns of foliar C:N:P:K:Ca:Mg, non-structural carbohydrate, and stable isotope in C. lanceolata seedlings; and (ii) what are the effects of the stoichiometric homeostasis, non-structural carbohydrate, and stable isotope on the growth of C. lanceolata seedlings under the warming scenarios? Addressing these questions is critical for the future cultivation and productivity of C. lanceolata seedlings
There was no significant difference in the height and ground diameter of C. lanceolata seedlings between the control and warming treatments (Table 1), soil temperature was increased and soil moisture was decreased under warming treatment (Figure 1)
Summary
The global average temperature has reportedly increased by 0.85◦C compared with the pre-industrial levels (IPCC, 2018), and this has raised widespread attention. Different methods, including greenhouses (Day et al, 2008), open top chambers (Nybakken et al, 2011), soil heating cables (Zhang et al, 2019), reflectors (Sardans et al, 2008a), and infrared heaters (Dijkstra et al, 2012), may have contributed to the differences in results (Yue et al, 2017) Many other factors, such as rainfall, developmental stage, and resource supply might affect the response of plant stoichiometry to warming (Han et al, 2011). One-time sampling only provides a “snapshot” of the plant’s response to warming, and the details of seasonal and interannual variations in these responses warrant further investigation (Ren et al, 2021)
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