Department of Biology, University of North Florida, Jacksonville, Florida, USA.
School of Forestry and Wildlife Sciences, Auburn University, Auburn, Alabama, USA.
Glob Chang Biol. 2022 Jan;28(2):612-629. doi: 10.1111/gcb.15938. Epub 2021 Oct 27.
Temperature acclimation of leaf respiration (R) is an important determinant of ecosystem responses to temperature and the magnitude of temperature-CO feedbacks as climate warms. Yet, the extent to which temperature acclimation of R exhibits a common pattern across different growth conditions, ecosystems, and plant functional types remains unclear. Here, we measured the short-term temperature response of R at six time points over a 10-month period in two coastal wetland species (Avicennia germinans [C mangrove] and Spartina alterniflora [C marsh grass]) growing under ambient and experimentally warmed temperatures at two sites in a marsh-mangrove ecotone. Leaf nitrogen (N) was determined on a subsample of leaves to explore potential coupling of R and N. We hypothesized that both species would reduce R at 25°C (R ) and the short-term temperature sensitivity of R (Q ) as air temperature (T ) increased across seasons, but the decline would be stronger in Avicennia than in Spartina. For each species, we hypothesized that seasonal temperature acclimation of R would be equivalent in plants grown under ambient and warmed temperatures, demonstrating convergent acclimation. Surprisingly, Avicennia generally increased R with increasing growth temperature, although the Q declined as seasonal temperatures increased and did so consistently across sites and treatments. Weak temperature acclimation resulted in reduced homeostasis of R in Avicennia. Spartina reduced R and the Q as seasonal temperatures increased. In Spartina, seasonal temperature acclimation was largely consistent across sites and treatments resulting in greater respiratory homeostasis. We conclude that co-occurring coastal wetland species may show contrasting patterns of respiratory temperature acclimation. Nonetheless, leaf N scaled positively with R in both species, highlighting the importance of leaf N in predicting respiratory capacity across a range of growth temperatures. The patterns of respiratory temperature acclimation shown here may improve the predictions of temperature controls of CO fluxes in coastal wetlands.
叶片呼吸作用（R）的温度驯化是生态系统对温度响应以及气候变暖时温度-CO 反馈幅度的重要决定因素。然而，R 的温度驯化在不同的生长条件、生态系统和植物功能类型中是否表现出共同的模式仍不清楚。在这里，我们在滨海湿地生态交错带的两个地点，测量了两种沿海湿地物种（红树植物海桑 [C 红树林] 和盐沼草互花米草 [C 盐沼草]）在 10 个月内的 6 个时间点的叶片呼吸作用对短期温度的响应，这些物种在环境温度和实验增温条件下生长。我们从部分叶片中测定了叶片氮（N），以探索 R 和 N 之间潜在的耦合关系。我们假设，随着季节的变化，两个物种的叶片呼吸作用在 25°C（R ）和短期温度敏感性（Q ）都会随着空气温度（T）的升高而降低，但在海桑中的下降幅度会大于互花米草。对于每个物种，我们假设在环境温度和增温条件下生长的植物的季节性温度驯化 R 是等效的，表现出趋同的驯化。令人惊讶的是，海桑的叶片呼吸作用通常随生长温度的升高而增加，尽管 Q 值随着季节温度的升高而下降，且在不同地点和处理中表现一致。弱的温度驯化导致海桑的呼吸作用的自我平衡能力降低。互花米草的 R 和 Q 值随着季节温度的升高而降低。在互花米草中，季节性温度驯化在很大程度上在不同的地点和处理中是一致的，从而导致更大的呼吸作用自我平衡能力。我们得出结论，共存的滨海湿地物种可能表现出不同的呼吸作用温度驯化模式。尽管如此，两种物种的叶片 N 与 R 呈正相关，突出了叶片 N 在预测一系列生长温度下的呼吸能力方面的重要性。这里显示的呼吸作用温度驯化模式可能会提高对滨海湿地 CO 通量温度控制的预测。
