scholarly journals Impacts of long-term land use on terrestrial organic matter input to lakes based on lignin phenols in sediment records from a Swedish forest lake

2021 ◽  
Vol 774 ◽  
pp. 145517
Author(s):  
Bingjie Yang ◽  
Karl Ljung ◽  
Anne Birgitte Nielsen ◽  
Elise Fahlgren ◽  
Dan Hammarlund
2019 ◽  
Author(s):  
Bingjie Yang ◽  
Anne Birgitte Nielsen ◽  
Karl Ljung ◽  
Elise Fahlgren ◽  
Anne Hormes ◽  
...  

Author(s):  
Trina Stephens

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.


2013 ◽  
Vol 10 (2) ◽  
pp. 1193-1207 ◽  
Author(s):  
S.-W. Duan ◽  
S. S. Kaushal

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.


Silicon ◽  
2020 ◽  
Author(s):  
Barbara von der Lühe ◽  
Laura Pauli ◽  
Britta Greenshields ◽  
Harold J. Hughes ◽  
Aiyen Tjoa ◽  
...  

Abstract The effects of land use and fire on ecosystem silicon (Si) cycling has been largely disregarded so far. We investigated the impacts of land use and fire on Si release from topsoils and litter of lowland rainforest and oil-palm plantations in Jambi Province, Indonesia. Lower concentrations of Si in amorphous silica (ASi) were found in oil-palm plantation topsoils (2.8 ± 0.7 mg g− 1) compared to rainforest (3.5 ± 0.8 mg g− 1). Higher total Si concentrations were detected in litter from oil-palm frond piles (22.8 ± 4.6 mg g− 1) compared to rainforest litter (12.7 ± 2.2 mg g− 1). To test the impact of fire, materials were burned at 300 °C and 500 °C and were shaken with untreated samples in simulated rainwater for 28 h. Untreated oil-palm topsoils showed a significantly lower Si release (p≤ 0.05) compared to rainforest. The fire treatments resulted in an increased Si release into simulated rainwater. Si release from oil-palm topsoils and litter increased by a factor of 6 and 9 (500 °C), respectively, and Si release from rainforest topsoils and litter by a factor of 3 and 9 (500 °C). Differences between land use were related to initial ASi and litter Si concentrations, and to losses of soil organic matter during burning. We conclude that transformation of rainforest into oil palm plantations could be an important and immediate Si source after a fire event but may indirectly lead to a decrease in the long-term Si availability to plants.


2020 ◽  
Author(s):  
Patthapong Chaiseanwang ◽  
Piyaphong Chenrai

<p>Fifteen samples were collected from coal mines Mae Than basins located in Lampang Province, Northern Thailand to investigate organic geochemical characterization which can provide organic matter input, thermal maturity and depositional environment. The total organic carbon (TOC) content of the coal samples ranges from 30.12 to 73.71 wt. %, while shales and mudstones value between 5.98 – 24.87 wt. %. The extractable organic matter (EOM) content of all samples, which is yielded from bitumen extraction, values in the range of 1,256 and 16,421 ppm indicating good to excellent hydrocarbon generation potential. The organic geochemical data were studied by using Gas-chromatography Mass-spectrometry (GC-MS) providincg biomarker and non-biomarker data. The thermal maturity of studied samples is represented as immature stage due to ratio of Ts/(Ts+Tm) and homohopane isomerization. The distribution of normal alkanes is predominantly long-chain normal alkanes with odd-numbered carbon. The high Carbon Preference Index (CPI) value of samples indicates terrestrial organic matter input. The depositional environment of the study area can be interpreted that the coal formation is occurred within an oxidizing condition with the majority of higher plant input, whereas shale and mudstone is slightly more anoxic-aquatic environment.</p>


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