Chin J Plant Ecol ›› 2016, Vol. 40 ›› Issue (3): 221-235.DOI: 10.17521/cjpe.2015.0243

• Research Articles • Previous Articles     Next Articles

Effects of air temperature and relative humidity on equilibrium moisture content and time-lag of forest land surface dead fine fuels

Hai-Qing HU1, Xin LU1, Long SUN1,*(), Zhi-Lin QU2, Yu LIANG1, Hai-Yang LI1   

  1. 1College of Forestry, Northeast Forestry University, Harbin 150040, China

    2College of Science, Northeast Forestry University, Harbin 150040, China
  • Received:2015-06-26 Revised:2015-11-27 Online:2016-03-10 Published:2016-03-25
  • Contact: Long SUN

Abstract: Aims

This study was conducted to determine the effects of air temperature and relative humidity on the equilibrium moisture content (EMC) and time-lag of forest dead fine fuels by taking Larix gmelinii leaves, Betula platyphylla leaves and mixture of L. gmelinii and B. platyphylla leaves as examples.

Methods

Measurements were made on moisture content of fuels under different air temperature and humidity conditions (a total of 20 temperature by relative humidity combinations). Equations describing the dynamics of moisture content of fine-grain fuels in three types of forests were developed and the EMC and time-lag were estimated. The moisture-time mode, EMC-temperature and EMC-relative humidity models, time-lag-temperature and time-lag-relative humidity models for fine-grain fuels were also established.

Important findings

Data were fit by four EMC models. The Van Wanger model gave the best fit with small errors (both mean absolute error (MAE) and root mean square error (RMAE) within 0.01); the performance of Nelson model was worst. Further analysis revealed that both air temperature and relative humidity significantly affected EMC and time-lag. Air temperature was negatively correlated with EMC and time-lag, whereas relative humidity was positively correlated with EMC and time-lag. Using the time-lag-relative humidity model overestimated the time-lag. There are some uncertainties and limitations remaining in the current analysis, and further research is needed on both desorption and absorption processes of fine fuels, with broader range of fuel types and more influencing factors.

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Key words: equilibrium moisture content, moisture content, dead fine fuel, relative humidity, air temperature, time-lag