scholarly journals Differences in Bacterial Diversity, Composition and Function due to Long-Term Agriculture in Soils in the Eastern Free State of South Africa

Diversity ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 61 ◽  
Author(s):  
Joel P. Dube ◽  
Angel Valverde ◽  
Joachim M. Steyn ◽  
Don A. Cowan ◽  
Jacqueline E. van der Waals
Keyword(s):  
South Africa ◽  
Land Use ◽  
Land Use Change ◽  
Bacterial Diversity ◽  
Agricultural Soil ◽  
Free State ◽  
Rrna Gene ◽  
And Function ◽  
Eastern Free State

Land-use change from natural to managed agricultural ecosystems significantly impacts soil bacterial diversity and function. The Eastern Free State (EFS) is one of the most productive agricultural regions in South Africa. However, no studies aiming to understand the changes in bacterial diversity, composition and function due to land-use change in this area have been conducted. This study investigated, using high-throughput 16S rRNA gene amplicon sequencing, the effects of long-term agriculture on bacterial diversity, composition and putative function in the EFS by comparing microbiomes from lands that have been under agronomic activity for over 50 years to those from uncultivated land. Results indicate that agriculture increased bacterial diversity. Soil chemical analysis showed that land-use shifted soils from being oligotrophic to copiotrophic, which changed bacterial communities from being Actinobacteria dominated to Proteobacteria dominated. Predictive functional analysis using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) suggested that agricultural soil was abundant in genes associated with plant fitness and plant growth promotion, while non-agricultural soil was abundant in genes related to organic matter degradation. Together, these results suggest that edaphic factors induced by long-term agriculture resulted in shifts in bacterial diversity and putative function in the EFS.

scholarly journals CH4and N2O fluxes in the Colorado shortgrass steppe: 2. Long-term impact of land use change

1997 ◽  
Vol 11 (1) ◽  
pp. 29-42 ◽  
Author(s):  
A. R. Mosier ◽  
W. J. Parton ◽  
D. W. Valentine ◽  
D. S. Ojima ◽  
D. S. Schimel ◽  
...  
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Shortgrass Steppe ◽  
N2o Fluxes ◽  
Long Term Impact

The Effects of Long‐Term Land‐Use Change on Soil Properties in Perth, Ontario Canada

2016 ◽  
Author(s):  
Trina Stephens
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
North America ◽  
Land Use Change ◽  
Soil Properties ◽  
Carbon Storage ◽  
Organic Matter Content ◽  
Matter Content ◽  
Topographic Gradients

Land‐use change can have a major impact on soil properties, leading to long‐term changes in soilnutrient cycling rates and carbon storage. While a substantial amount of research has been conducted onland‐use change in tropical regions, empirical evidence of long‐term conversion of forested land toagricultural land in North America is lacking. Pervasive deforestation for the sake of agriculturethroughout much of North America is likely to have modified soil properties, with implications for theglobal climate. Here, we examined the response of physical, chemical and biological soil properties toconversion of forest to agricultural land (100 years ago) on Roebuck Farm near Perth, Ontario, Canada.Soil samples were collected at three sites from under forest and agricultural vegetative cover on bothhigh‐ and low‐lying topographic positions (12 locations in total; soil profile sampled to a depth of 40cm).Our results revealed that bulk density, pH, and nitrate concentrations were all higher in soils collectedfrom cultivate sites. In contrast, samples from forested sites exhibited greater water‐holding capacity,porosity, organic matter content, ammonia concentrations and cation exchange capacity. Many of these characteristics are linked to greater organic matter abundance and diversity in soils under forestvegetation as compared with agricultural soils. Microbial activity and Q10 values were also higher in theforest soils. While soil properties in the forest were fairly similar across topographic gradients, low‐lyingpositions under agricultural regions had higher bulk density and organic matter content than upslopepositions, suggesting significant movement of material along topographic gradients. Differences in soilproperties are attributed largely to increased compaction and loss of organic matter inputs in theagricultural system. Our results suggest that the conversion of forested land cover to agriculture landcover reduces soil quality and carbon storage, alters long‐term site productivity, and contributes toincreased atmospheric carbon dioxide concentrations.

Response of phosphorus fractions to land-use change followed by long-term fertilization in a sub-alpine humid soil of Qinghai–Tibet plateau

2018 ◽  
Vol 19 (3) ◽  
pp. 1109-1119 ◽  
Author(s):  
Xiaolei Sun ◽  
Meng Li ◽  
Guoxi Wang ◽  
Marios Drosos ◽  
Fulai Liu ◽  
...  
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Phosphorus Fractions ◽  
Tibet Plateau ◽  
Qinghai Tibet Plateau

scholarly journals Warming increases carbon and nutrient fluxes from sediments in streams across land use

2013 ◽  
Vol 10 (2) ◽  
pp. 1193-1207 ◽  
Author(s):  
S.-W. Duan ◽  
S. S. Kaushal
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Land Use Change ◽  
Sulfate Reduction ◽  
Organic Matter Content ◽  
Soluble Reactive Phosphorus ◽  
Overlying Water ◽  
Sediment Fluxes ◽  
Urban Sites

Abstract. Rising water temperatures due to climate and land use change can accelerate biogeochemical fluxes from sediments to streams. We investigated impacts of increased streamwater temperatures on sediment fluxes of dissolved organic carbon (DOC), nitrate, soluble reactive phosphorus (SRP) and sulfate. Experiments were conducted at 8 long-term monitoring sites across land use (forest, agricultural, suburban, and urban) at the Baltimore Ecosystem Study Long-Term Ecological Research (LTER) site in the Chesapeake Bay watershed. Over 20 yr of routine water temperature data showed substantial variation across seasons and years. Lab incubations of sediment and overlying water were conducted at 4 temperatures (4 °C, 15 °C, 25 °C, and 35 °C) for 48 h. Results indicated: (1) warming significantly increased sediment DOC fluxes to overlying water across land use but decreased DOC quality via increases in the humic-like to protein-like fractions, (2) warming consistently increased SRP fluxes from sediments to overlying water across land use, (3) warming increased sulfate fluxes from sediments to overlying water at rural/suburban sites but decreased sulfate fluxes at some urban sites likely due to sulfate reduction, and (4) nitrate fluxes showed an increasing trend with temperature at some forest and urban sites but with larger variability than SRP. Sediment fluxes of nitrate, SRP and sulfate were strongly related to watershed urbanization and organic matter content. Using relationships of sediment fluxes with temperature, we estimate a 5 °C warming would increase mean sediment fluxes of SRP, DOC and nitrate-N across streams by 0.27–1.37 g m−2 yr−1, 0.03–0.14 kg m−2 yr−1, and 0.001–0.06 kg m−2 yr−1. Understanding warming impacts on coupled biogeochemical cycles in streams (e.g., organic matter mineralization, P sorption, nitrification, denitrification, and sulfate reduction) is critical for forecasting shifts in carbon and nutrient loads in response to interactive impacts of climate and land use change.

scholarly journals Soil microbial community dynamics and assembly under long-term land use change

2017 ◽  
Vol 93 (10) ◽  
Author(s):  
Dennis Goss-Souza ◽  
Lucas William Mendes ◽  
Clovis Daniel Borges ◽  
Dilmar Baretta ◽  
Siu Mui Tsai ◽  
...  
Keyword(s):  
Land Use ◽  
Microbial Community ◽  
Land Use Change ◽  
Soil Microbial Community ◽  
Community Dynamics ◽  
Soil Microbial ◽  
Microbial Community Dynamics

scholarly journals Most Mexican hummingbirds lose under climate and land-use change: Long-term conservation implications

2021 ◽  
Author(s):  
David A. Prieto-Torres ◽  
Laura E. Nuñez Rosas ◽  
Daniela Remolina Figueroa ◽  
María del Coro Arizmendi
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Conservation Implications

scholarly journals Diversity of siderophore-producing bacterial cultures from Carlsbad Caverns National Park caves, Carlsbad, New Mexico

2021 ◽  
Vol 83 (1) ◽  
pp. 29-43
Author(s):  
Tammi Duncan ◽  
Margaret Werner-Washburne ◽  
Diana Northup
Keyword(s):  
National Park ◽  
Ferric Iron ◽  
16S Rrna Gene Sequencing ◽  
Siderophore Production ◽  
Rrna Gene ◽  
Hydroxamate Siderophores ◽  
Rrna Gene Sequencing ◽  
And Function ◽  
Ferromanganese Deposits

Siderophores are microbially-produced ferric iron chelators. They are essential for microbial survival, but their presence and function for cave microorganisms have not been extensively studied. Siderophores are classified based on the common functional groups (catechols, hydroxamates, carboxylates, and mixed) that coordinate to ferric (Fe3+) iron. Cave environments are nutrient-limited and previous evidence suggests siderophore usage in carbonate caves. We hypothesize that siderophores are likely used as a mechanism in caves to obtain critical ferric iron. Cave bacteria were collected from long-term parent cultures (LT PC) or short-term parent cultures (ST PC) inoculated with ferromanganese deposits (FMD) and carbonate secondary minerals from Lechuguilla and Spider caves in Carlsbad Caverns National Park, NM. LT PC were incubated for 10−11 years to identify potential chemolithoheterotrophic cultures able to survive in nutrient-limited conditions. ST PC were incubated for 1−3 days to identify a broader diversity of cave isolates. A total of 170 LT and ST cultures, 18 pure and 152 mixed, were collected and used to classify siderophore production and type and to identify siderophore producers. Siderophore production was slow to develop (>10 days) in LT cultures with a greater number of weak siderophore producers in comparison to the ST cultures that produced siderophores in <10 days, with a majority of strong siderophore producers. Overall, 64% of the total cultures were siderophore producers, with the majority producing hydroxamate siderophores. Siderophore producers were classified into Proteobacteria (Alpha-, Beta-, or Gamma-), Actinobacteria, Bacteroidetes, and Firmicutes phyla using 16S rRNA gene sequencing. Our study supports our hypothesis that cave bacteria have the capability to produce siderophores in the subsurface to obtain critical ferric iron.

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