Moss regulates soil evaporation leading to decoupling of soil and near-surface air temperatures
- 55 Downloads
Moss covers a vast area from the polar to the tropics on a global scale and has important regulatory effects on the biogeochemical processes in the soil. Previous studies had shown that moss on soil could reduce soil temperature in the warm period and plays an important role in the stability of the soil carbon pool in the context of global warming. The cooling effect of soil temperature by moss may be due to its ability to accelerate soil water evaporation. Most vascular plants achieve limited homeothermy by transpiration, but moss has no organs which can regulate transpiration. Can moss also regulate soil water evaporation as the transpiration of vascular plants? The objective of this study was to determine the differences in temperature and evaporation between moss-covered and bare soil.
Materials and methods
A year-round mesocosm experiment was carried out to investigate soil temperature and evaporation with and without moss. We used a high time-resolution instrument which could simultaneously monitor soil temperature beneath moss layers, photosynthetically active radiation, and near-surface air temperature (20 cm above the soil) in a 10-min interval. In the meantime, we used a chamber method to monitor soil evaporation and heat flux inside the mesocosms simultaneously.
Results and discussion
We found that the evaporation of the moss increased drastically when near-surface air temperature exceeded 30 °C, which kept maximum soil temperature around 30 °C. This finding was different from many previous studies which reported that the evaporation of moss was always greater than bare soil or similar to open water surface. The phenomenon we found may be important for moss, which allowed moss to minimize the loss of water at high temperature and maintain a relatively constant temperature. It is known that moss is a C3 plant, and the high-temperature threshold for the photosynthesis of C3 vascular plants is also around 30 °C. Thus, the temperature-regulating behavior could improve the net carbon gain for moss and benefit for its survival. To our best knowledge, there is no research reporting this phenomenon. In the context of global warming, the temperature-regulating behavior of moss is very important for its controls on soil carbon dynamics and its other ecological functions, especially at lower latitudes with higher soil temperature.
Our result showed that moss can also achieve limited homeothermy through soil water evaporation similarly as the vascular plant through transpiration, and the temperature threshold was around 30 °C. This homeothermy led to the decoupling of soil temperature and near-surface air temperature. How mosses elevate water evaporation in response to high temperature remains to be a challenge for future research.
KeywordsDecouple Evaporation Homeotherms Moss Soil temperature Transpiration
We thank Dr. Francis Bowles for helping with the design of the environmental factor monitoring system.
This research was supported by the Joint Fund for the Promotion of Cross-strait Cooperation in Science and Technology (U1505233), the National “973” Program of China (2014CB954003), and the National Natural Science Foundation of China (31500506).
- Gates D, Hiesey W, Milner H, Nobs M (1964) Temperatures of Mimulus leaves in natural environments and in a controlled chamber. Carnegie Inst Wash Yearbook 63:418–428Google Scholar
- Heijmans MM, Arp WJ, Chapin FS (2004) Controls on moss evaporation in a boreal black spruce forest. Glob Biogeochem Cycles 18(2). https://doi.org/10.1029/2003GB002128
- Jácome J, Gradstein S, Kessler M (2011) Responses of epiphytic bryophyte communities to simulated climate change in the tropics. Bryophyte ecology and climate change. Cambridge University Press, New York, pp 191–207Google Scholar
- Rice SK, Cornelissen JHC (2014) Best practices for measuring photosynthesis at multiple scales, photosynthesis in bryophytes and early land plants. Springer, pp 79–93Google Scholar
- Soil Survey Staff of USDA (2014) Soil Survey Staff, 2014. Natural Resources Conservation Service 2014 National Soil Survey Handbook. Title 430-VI. U.S. Government Printing Office Washington D.C. Sec 602Google Scholar
- Stoy PC, Street LE, Johnson AV, Prieto-Blanco A, Ewing SA (2012) Temperature, heat flux, and reflectance of common subarctic mosses and lichens under field conditions: might changes to community composition impact climate-relevant surface fluxes? Arct Antarct Alp Res 44:500–508CrossRefGoogle Scholar
- Shen T, Corlett RT, Song L, Ma WZ, Guo XL, Song Y, Wu Y (2018) Vertical gradient in bryophyte diversity and species composition in tropical and subtropical forests in Yunnan, SW China. J Veg Sci 29: 1075–1087Google Scholar
- Yamori W, Hikosaka K, Way DA (2014) Temperature response of photosynthesis in C3, C4, and CAM plants: temperature acclimation and temperature adaptation. Photosynthesis Res 119:101–117Google Scholar