Land use modifies the inherent effect of soil properties on soil bacterial communities in humid tropical watersheds

De Caires, Sunshine A.; Reinsch, Sabine; Saravanakumar, Duraisamy; St. Martin, Chaney; Wuddivira, Mark N.; Zebarth, Bernie J.; Kaya, Fuat; Liu, Mengying; Chinthalapudi, Durga P.M.; Shanmugam, Shankar Ganapathi; Helgason, Bobbi

Land use modifies the inherent effect of soil properties on soil bacterial communities in humid tropical watersheds

De Caires, Sunshine A. ORCID: https://orcid.org/0000-0001-9922-1580; Reinsch, Sabine ORCID: https://orcid.org/0000-0003-4649-0677; Saravanakumar, Duraisamy; St. Martin, Chaney; Wuddivira, Mark N. ORCID: https://orcid.org/0000-0003-2475-829X; Zebarth, Bernie J.; Kaya, Fuat ORCID: https://orcid.org/0000-0003-0011-9020; Liu, Mengying; Chinthalapudi, Durga P.M. ORCID: https://orcid.org/0000-0002-4377-1097; Shanmugam, Shankar Ganapathi ORCID: https://orcid.org/0000-0001-5598-309X; Helgason, Bobbi ORCID: https://orcid.org/0000-0003-1664-8250. 2025 Land use modifies the inherent effect of soil properties on soil bacterial communities in humid tropical watersheds [in special issue: Land use and management on soil properties and processes: 2nd ed.] Soil Systems, 9 (4), 112. 27, pp. 10.3390/soilsystems9040112

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Official URL: https://doi.org/10.3390/soilsystems9040112

Abstract/Summary

Soil bacterial communities are vital for ecosystem functioning in the humid tropics, yet their response to land-use change remains poorly understood. This knowledge gap is exacerbated by the lack of long-term studies. We employed a space-for-time substitution approach to assess the effects of land-use intensification on soil bacterial communities across a gradient of anthropogenic disturbance in Trinidad. Three sub-watersheds (Arouca = pristine, Maracas = intermediate, Tacarigua = intensive) were selected, each containing adjacent forest, grassland, and agricultural land uses. We combined geophysical soil apparent electrical conductivity (ECa-directed) sampling with 16S rDNA gene amplicon sequencing to characterize bacterial communities and their relationships with soil and landscape properties. Soil properties were the primary determinant of bacterial community structure, explaining 56% of the variation (p < 0.001), with pH, clay content, hygroscopic water, and nutrient availability as key drivers. Bacterial α-diversity differed significantly among sub-watersheds (p < 0.01), with Tacarigua exhibiting lower richness and diversity compared to Arouca and Maracas, but not across land uses. While a core microbiome of ten bacterial families was ubiquitous across land uses, indicating a stable foundational community, land-use intensification significantly altered β-diversity (p < 0.01 among sub-watersheds). Agricultural soils showed the greatest divergence from forest soils (p < 0.05), with a marked decline in key Proteobacterial families (e.g., Xanthomonadaceae, Pseudomonadaceae) involved in nutrient cycling and plant growth promotion. Although inherent soil properties shape the core microbiome, land-use intensification acts as a strong secondary filter, shifting soil bacterial communities toward more stress-resistant Firmicutes with potentially less diverse functions. Our findings demonstrate the utility of integrating space-for-time substitution with molecular profiling to predict long-term microbial responses to environmental change in vulnerable tropical ecosystems.

Item Type:

Publication - Article

Digital Object Identifier (DOI):

10.3390/soilsystems9040112

UKCEH and CEH Sections/Science Areas:

Environmental Pressures and Responses (2025-)

ISSN:

2571-8789

Additional Information:

Open Access paper - full text available via Official URL link.

Additional Keywords:

β-diversity, land-use change, proximal soil sensing, soil microbiome, space-for-time substitution, tropical soils