Influence of soil pedological properties on termite mound stability

Published Date

15 January 2016, Vol.262:45–51, doi:10.1016/j.geoderma.2015.08.020

Title 

Influence of soil pedological properties on termite mound stability

• Author 

• P. Jouquet ^a,b,,
• N. Guilleux ^a,b
• L. Caner ^c
• S. Chintakunta ^b
• M. Ameline ^b
• R.R. Shanbhag ^d

• aInstitute of Ecology and Environmental Sciences (UMR 242 iEES Paris), Institute of Research for Development (IRD), 32 av. H. Varagnat, 93143 Bondy, France
• bIndo-French Cell for Water Science (IFCWS), Civil engineering Department, Indian Institute of Science, 560 012 Bangalore, Karnataka, India
• cUniversité de Poitiers, IC2MP-HydrASA UMR 7285, B35, 5 rue Albert Turpain, TSA51106, 86073 Poitiers, France
• dInstitute of Wood Science and Technology, Malleswaram, 560 003 Bangalore, Karnataka, India

Received 7 April 2015. Revised 13 July 2015. Accepted 12 August 2015. Available online 25 August 2015.

Highlights

• •
  Termite mound density is similar in ferralsol and in vertisol.
• •
  Stability of termite mound aggregates is reduced compared to control.
• •
  Degradation of termite nests by rain is more important in vertisol than ferralsol.
• •
  Termites impact differently soil dynamics depending on the environment.

Abstract

This study investigated the influence of soil properties on the density and shape of epigeous fungus-growing termite nests in a dry deciduous forest in Karnataka, India. In this environment, Odontotermes obesus produces cathedral shaped mounds. Their density, shape (height and volume) and soil physicochemical properties were analyzed in ferralsol and vertisol environments. No significant difference was observed in O. obesus mound density (n = 2.7 mound ha^{− 1} on average in the vertisol and ferralsol areas). This study also showed that O. obesus has a limited effect on soil physical properties. No differences in soil particle size, pH, or the C:N ratio and base saturation were measured whereas the C and N contents were reduced and CEC was higher in termite nest soils in both environments. Clay mineralogical composition was also measured, and showed the presence of higher amounts of smectite clays in termite nest soils, which thus explained the increasing CEC despite the reduced C and N content. However, the main difference was the shape of the termite mounds. The degradation of the nests created a hillock of eroded soil at the base of termite mounds in the vertisol while only a thin layer of eroded soil was observed in the ferralsol. The increased degradation of termite mounds in the vertisol is explained by the presence of smectites (2:1 swelling clays), which confer macroscopic swelling and shrinking characteristics to the soil. Soil shrinkage during the dry season leads to the formation of deep cracks in the termite mounds that allow rain to rapidly penetrate inside the mound wall and then breakdown unstable aggregates. In conclusion, it appears that despite a similar abundance, termite mound properties depend to a large extent on the soil properties of their environments.

Keywords

• Ferralsol
• Vertisol
• Odontotermes obesus
• India
• Aggregate
• Termite mound shape
• Clay mineralogical properties

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• ⁎ 
  Corresponding author at: UMR 242, iEES-Paris, IRD, 32 av. H. Varagnat, 93143 Bondy, France.

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