Soil Chemical Properties and Biological Processes Under Pine Trees With and Without Dendroctonus Bark Beetle Infestation

ABSTRACT

Pine forests are highly appreciated for the ecosystem services and raw materials they provide to society. However, insect pests are a constant threat. Bark beetles of the genus Dendroctonus are responsible for the high mortality that prevails in pine forests. Studies suggest that their presence can be related to changes in physicochemical and biological soil’s properties. The question is: How do the chemical properties of the soil and the biological processes change in pine trees with and without Dendroctonus? We analyze variables such as pH, nitrogen reserves (N), total carbon (C), C/N ratio, cation exchange capacity (CEC), and macronutrient concentrations in soils under Pinus montezumae Lamb infested with Dendroctonus spp. and under healthy trees (same specie), as a control. The trees were grouped into three categories, according to the number of Dendroctonus resin’s lumps they presented. The functional diversity of soil bacteria was evaluated with Shannon-Weiner index. Significant differences were found in the contents of Ca, ammonium (NH4), and iron (Fe), they decrease while the frequency of lumps increases. The functional diversity of soil bacteria was higher in soils under asymptomatic pines. Taken together, our results show that Dendroctonus may be related to biological processes instead of chemical soil variables.

KEYWORDS:

• Bark beetle
• gen III biolog
• conifers
• Shannon H’ index
• volcanic soil

Acknowledgments

To CONACyt for the Master’s scholarship (792447) awarded to the first author. The authors would like to thank the following persons for their work and support during fieldwork: Sara I. Martínez González, E.I. Rosa I. Galán Breth, E. I. Ángel F. Zaragoza Méndez, Rodolfo Sánchez González and Arturo Sánchez González. Also, our gratitude to Sandra Rocha, Lourdes Cruz, Karla Tapia, and Ninfa Portilla for their work at the Soil Lab of the Instituto de Ecología, A. C., and to Ofelia Ferrera Rodríguez for her support at the Environmental Microbiology Lab of the Instituto de Ecología, Campus 3.