scholarly journals Fungal Biodiversity Mediates the Effects of Drying on Freshwater Ecosystem Functioning

Ecosystems ◽  
2021 ◽  
Author(s):  
Rebeca Arias-Real ◽  
Cayetano Gutiérrez-Cánovas ◽  
Isabel Muñoz ◽  
Cláudia Pascoal ◽  
Margarita Menéndez
Keyword(s):  
Organic Matter ◽  
Ecosystem Functioning ◽  
Fungal Biomass ◽  
Ecosystem Processes ◽  
Freshwater Ecosystems ◽  
Organic Matter Decomposition ◽  
Data Set ◽  
Positive Effects ◽  
Fungal Biodiversity ◽  
Manipulative Experiments

AbstractInvestigating the influence of biodiversity on ecosystem functioning over environmental gradients is needed to anticipate ecosystem responses to global change. However, our understanding of the functional role of freshwater biodiversity, especially for microbes, is mainly based on manipulative experiments, where biodiversity and environmental variability are minimized. Here, we combined observational and manipulative experiments to analyse how fungal biodiversity responds to and mediates the impacts of drying on two key ecosystem processes: organic matter decomposition and fungal biomass accrual. Our observational data set consists of fungal biodiversity and ecosystem processes from 15 streams spanning a natural gradient of flow intermittence. Our manipulative design evaluates the responses of ecosystem processes to two fungal richness levels crossed with three levels of drying. For the observational experiment, we found that increasing the duration of drying reduced fungal species richness and caused compositional changes. Changes in species composition were driven by species turnover, suggesting resistance mechanisms to cope with drying. We also found that fungal richness had a positive effect on organic matter decomposition and fungal biomass accrual. Positive effects of fungal biodiversity were consistent when controlling for the effects of drying duration on richness by means of structural equation modelling. In addition, our results for the manipulative experiment showed that the positive effects of higher richness on both ecosystem processes were evident even when exposed to short or long simulated drying. Overall, our study suggests that maintaining high levels of biodiversity is crucial for maintaining functional freshwater ecosystems in response to ongoing and future environmental changes.

Influence of carbon and nitrogen on cellulose and lignin degradation in forest soils

1995 ◽  
Vol 25 (8) ◽  
pp. 1231-1236 ◽  
Author(s):  
James A. Entry ◽  
Carole B. Backman
Keyword(s):  
Organic Matter ◽  
Soil Type ◽  
Fungal Biomass ◽  
Lignin Degradation ◽  
Cellulose Degradation ◽  
Bacterial Biomass ◽  
Terrestrial Ecosystems ◽  
Organic Matter Decomposition ◽  
Decomposition Rates ◽  
C And N

The concentration of lignin in plant tissue is a major factor controlling organic matter decomposition rates in terrestrial ecosystems. Microcosms were used to determine the influence of C and N additions on active bacterial and active fungal biomass, cellulose degradation, and lignin degradation at 4, 8, and 12 weeks in soils from the Tuskeege National Forest in southern Alabama. Active bacterial and active fungal biomass was determined by direct microscopy; cellulose and lignin degradation were measured radiometrically. The experimental design was a 33 latin square. Treatments were as follows: soil type, soil C (soils amended with the equivalent of 0, 400, or 800 kg C•ha−1 as cellulose), and soil N (soils amended with the equivalent of 0, 250, or 500 kg N•ha−1 as NH4NO3). Active bacterial biomass, active fungal biomass, and cellulose and lignin degradation did not differ with soil type. Active bacterial biomass was not affected by N or C additions. As C and N concentrations increased, active fungal biomass as well as cellulose and lignin degradation increased. The concentration of C and N (together) in the soil correlated with both cellulose and lignin degradation (r2 = 0.76, p < 0.001; r2 = 0.44, p < 0.001, respectively). Active fungal biomass correlated curvilinearly with both cellulose and lignin degradation (r2 = 0.38, p < 0.001; r2 = 0.33, p < 0.001, respectively). The lignin:N ratio is often used to predict organic matter decomposition rates in terrestrial ecosystems. These results lead us to conclude that a cellulose:lignin:N ratio may be a more accurate predictor of organic matter decomposition rates than C:N ratio or lignin:N ratios.

Design and test of a generic cohort model of soil organic matter decomposition: the SOMKO model

2001 ◽  
Vol 10 (6) ◽  
pp. 639-660 ◽  
Author(s):  
Jacques Gignoux ◽  
Joanna House ◽  
David Hall ◽  
Dominique Masse ◽  
Hassan B. Nacro ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Organic Matter Decomposition ◽  
Cohort Model ◽  
Soil Organic Matter Decomposition

scholarly journals Microfinance and Vulnerability to Seasonal Famine in a Rural Economy: Evidence from Monga in Bangladesh

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Claudia Berg ◽  
M. Shahe Emran
Keyword(s):  
Food Security ◽  
Rural Economy ◽  
Screening Process ◽  
Data Set ◽  
Estimation Strategy ◽  
Positive Effects ◽  
Unique Data ◽  
Primary Mechanism ◽  
Poor Households ◽  
Microfinance Institution

AbstractThis paper uses a unique data set on 143,000 poor households from Northern Bangladesh to analyze the effects of microfinance membership on a household’s ability to cope with seasonal famine known as Monga. We develop an identification and estimation strategy that exploits a jump and a kink at the 10-decimal land ownership-threshold driven by the Microfinance Institution screening process to ensure repayment by excluding the ultra-poor. Evidence shows that microfinance membership improves food security during Monga, especially for the poorest households who survive at the margin of one and two meals a day. The positive effects on food security are, however, not driven by higher income, as microcredit does not improve the ability to migrate for work, nor does it reduce dependence on distress sale of labor. The evidence is consistent with consumption smoothing being the primary mechanism behind the gains in food security of MFI households during the season of starvation.

scholarly journals Microfinance and Vulnerability to Seasonal Famine in a Rural Economy: Evidence from Monga in Bangladesh

2020 ◽  
Vol 20 (3) ◽  
Author(s):  
Claudia Berg ◽  
M. Shahe Emran
Keyword(s):  
Food Security ◽  
Rural Economy ◽  
Screening Process ◽  
Data Set ◽  
Estimation Strategy ◽  
Positive Effects ◽  
Unique Data ◽  
Primary Mechanism ◽  
Poor Households ◽  
Microfinance Institution

AbstractThis paper uses a unique data set on 143,000 poor households from Northern Bangladesh to analyze the effects of microfinance membership on a household's ability to cope with seasonal famine known as Monga. We develop an identification and estimation strategy that exploits a jump and a kink at the 10 decimal land ownership-threshold driven by the Microfinance Institution (MFI) screening process to ensure repayment by excluding the ultra-poor. Evidence shows that microfinance membership improves food security during Monga, especially for the poorest households who survive at the margin of one and two meals a day. The positive effects on food security are, however, not driven by higher income, as microcredit does not improve the ability to migrate for work, nor does it reduce dependence on distress sale of labor. The evidence is consistent with consumption smoothing being the primary mechanism behind the gains in food security of MFI households during the season of starvation.

Soil drying and organic matter decomposition

1967 ◽  
Vol 26 (2) ◽  
pp. 269-276 ◽  
Author(s):  
W. O. Enwezor
Keyword(s):  
Organic Matter ◽  
Organic Matter Decomposition ◽  
Soil Drying

A generally applicable pedotransfer function that estimates field capacity and permanent wilting point from soil texture and bulk density

2008 ◽  
Vol 88 (5) ◽  
pp. 761-774 ◽  
Author(s):  
J. A. P. Pollacco
Keyword(s):  
Organic Matter ◽  
Soil Moisture ◽  
Bulk Density ◽  
Soil Texture ◽  
The United States ◽  
Pedotransfer Functions ◽  
Pedotransfer Function ◽  
Data Set ◽  
Wide Range ◽  
Fitting Parameters

Hydrological models require the determination of fitting parameters that are tedious and time consuming to acquire. A rapid alternative method of estimating the fitting parameters is to use pedotransfer functions. This paper proposes a reliable method to estimate soil moisture at -33 and -1500 kPa from soil texture and bulk density. This method reduces the saturated moisture content by multiplying it with two non-linear functions depending on sand and clay contents. The novel pedotransfer function has no restrictions on the range of the texture predictors and gives reasonable predictions for soils with bulk density that varies from 0.25 to 2.16 g cm-3. These pedotransfer functions require only five parameters for each pressure head. It is generally accepted that the introduction of organic matter as a predictor improves the outcomes; however it was found by using a porosity based pedotransfer model, using organic matter as a predictor only modestly improves the accuracy. The model was developed employing 18 559 samples from the IGBP-DIS soil data set for pedotransfer function development (Data and Information System of the International Geosphere Biosphere Programme) database that embodies all major soils across the United States of America. The function is reliable and performs well for a wide range of soils occurring in very dry to very wet climates. Climatical grouping of the IGBP-DIS soils was proposed (aquic, tropical, cryic, aridic), but the results show that only tropical soils require specific grouping. Among many other different non-climatical soil groups tested, only humic and vitric soils were found to require specific grouping. The reliability of the pedotransfer function was further demonstrated with an independent database from Northern Italy having heterogeneous soils, and was found to be comparable or better than the accuracy of other pedotransfer functions found in the literature. Key words: Pedotransfer functions, soil moisture, soil texture, bulk density, organic matter, grouping

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