**5. Conclusion**

The underlying mechanisms that influence feedbacks and vegetation dynamics within a complex plant-microbial community interaction are largely unresolved [4, 56]. Soil ecosystems are dynamic and diverse, and their physicochemical characteristics vary spatially and temporally. In this study, we compared and contrasted the intra-microbial abundance and diversity of a pasture site in two sampling periods and sampling methods. Our results showed that several classes of soil microbes instrumental in soil nutrient cycling, plant health, plant organic matter decomposition, and soil stabilization were present. These included in order of abundance: bacteria (63%), AMF (17%), saprophytic fungi (9%), actinomycetes (8%), and micro-eukaryotes (3%). The composition of the soil communities changed with the falling temperature, with bacterial abundance diminishing by up to 10% from August to October with a similar magnitude of increase in AMF observed during the same period. Our results showed that the soil bacterial communities were primarily influenced by abiotic conditions, while fungal communities were shaped by the biotic environment such as the plant species such as seen during the flush of regrowth by brome grass (cool season grass) and reallocation of nutrients to root growth that contributed to AMF rapid proliferation and abundance. These findings may provide reasonable evidence that a prolonged positive feedback between brome grass plant-AMF microbial interactions elicits subsequent biases toward the continued dominance and development of brome grass monoculture in a site that was once natural grassland.

Our findings showed that the random sampling technique has the same sensitivity and reliability as an ECa-based method in capturing the spatial and temporal dynamics of soil microbiota and can thus be used as a method of choice for sites with a relatively low range of ECa variability, indicative of similar soil chemical, physical, and microbial properties, especially in locations with established legacy effects (in our case, more than 20 years of a brome grass monoculture). Our findings support and add to new information regarding temporal changes in plant-climate-soil interactions which have not been conducted previously for pasture sites dominated by cool-season grasses such as brome grass over several decades of development.

**185**

**Author details**

, Jane Asiyo Okalebo1

\* and Shaokun Wang2

2 Urat Desert-Grassland Research Station, Northwest Institute of Eco-Environment

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

1 School of Natural Resources, University of Nebraska, Lincoln, NE, USA

and Resources, Chinese Academy of Sciences, Lanzhou, China

\*Address all correspondence to: jane.okalebo@gmail.com

provided the original work is properly cited.

Taity Changa1

*Spatio-Temporal Dynamics of Soil Microbial Communities in a Pasture: A Case Study…*

The authors acknowledge an internal funding grant provided by the University of Nebraska-Lincoln's Research and Development Office and Agricultural Research Service (ARS), USDA. We acknowledge Les Howard and Paul Koerner for their

*DOI: http://dx.doi.org/10.5772/intechopen.93548*

**Acknowledgements**

**Abbreviations**

valuable technical assistance.

N nitrogen

OC organic carbon WDRF BpH Woodruff buffer pH

pH potential of hydrogen

ECa apparent electroconductivity

*Spatio-Temporal Dynamics of Soil Microbial Communities in a Pasture: A Case Study… DOI: http://dx.doi.org/10.5772/intechopen.93548*
