The lack of clarity of how natural vegetation restoration influences soil organic carbon(SOC) content and SOC components in soil aggregate fractions limits the understanding of SOC sequestration and turnover in forest...The lack of clarity of how natural vegetation restoration influences soil organic carbon(SOC) content and SOC components in soil aggregate fractions limits the understanding of SOC sequestration and turnover in forest ecosystems.The aim of this study was to explore how natural vegetation restoration affects the SOC content and ratio of SOC components in soil macroaggregates(>250 μm), microaggregates(53–250 μm), and silt and clay(<53 μm) fractions in 30-, 60-, 90-and 120-year-old Liaodong oak(Quercus liaotungensis Koidz.) forests, Shaanxi, China in 2015.And the associated effects of biomasses of leaf litter and different sizes of roots(0–0.5, 0.5–1.0, 1.0–2.0 and >2.0 mm diameter) on SOC components were studied too.Results showed that the contents of high activated carbon(HAC), activated carbon(AC) and inert carbon(IC) in the macroaggregates, microaggregates and silt and clay fractions increased with restoration ages.Moreover, IC content in the microaggregates in topsoil(0–20 cm) rapidly increased;peaking in the 90-year-old restored forest, and was 5.74 times higher than AC content.In deep soil(20–80 cm), IC content was 3.58 times that of AC content.Biomasses of 0.5–1.0 mm diameter roots and leaf litter affected the content of aggregate fractions in topsoil, while the biomass of >2.0 mm diameter roots affected the content of aggregate fractions in deep soil.Across the soil profiles, macroaggregates had the highest capacity for HAC sequestration.The effects of restoration ages on soil aggregate fractions and SOC content were less in deep soil than in topsoil.In conclusion, natural vegetation restoration of Liaodong oak forests improved the contents of SOC, especially IC within topsoil and deep soil.The influence of IC on aggregate stability was greater than the other SOC components, and the aggregate stability was significantly affected by the biomasses of litter, 0.5–1.0 mm diameter roots in topsoil and >2.0 mm diameter roots in deep soil.Natural vegetation restoration of Liaodong oak forests pr展开更多
Background:Forest soils in tropical and subtropical areas store a significant amount of carbon.Recent framework to assess soil organic matter(SOM)dynamics under evolving global conditions suggest that dividing bulk SO...Background:Forest soils in tropical and subtropical areas store a significant amount of carbon.Recent framework to assess soil organic matter(SOM)dynamics under evolving global conditions suggest that dividing bulk SOM into particulate and mineral-associated organic matter(POM vs.MAOM)is a promising method for identifying how SOM contributes to reducing global warming.Soil macrofauna,earthworms,and millipedes have been found to play an important role in facilitating SOM processes.However,how these two co-existing macrofaunae impac the litter decomposition process and directly impact the formation of POM and MAOM remains unclear.Methods:Here,we set up a microcosm experiment,which consisted of 20 microcosms with four treatments earthworm and litter addition(E),millipedes and litter addition(M),earthworm,millipedes,and litter addition(E+M),and control(only litter addition)in five replicates.The soil and litter were sterilized prior to beginning the incubation experiment to remove any existing microbes.After incubating the samples for 42 days,the litte properties(mass,C,and N contents),soil physicochemical properties,as well as the C and N contents,and POM and MAOM^(13)C abundance in the 0–5 and 5–10 cm soil layers were measured.Finally,the relative influences o soil physicochemical and microbial properties on the distribution of C and N in the soil fractions were analyzed Results:The litter mass,C,and N associated with all four treatments significantly decreased after incubation especially under treatment E+M(litter mass:-58.8%,litter C:-57.0%,litter N:-75.1%,respectively),while earthworm biomass significantly decreased under treatment E.Earthworm or millipede addition alone showed no significant effects on the organic carbon(OC)and total nitrogen(TN)content in the POM fraction,but join addition of both significantly increased OC and TN regardless of soil depth.Importantly,all three macrofauna treatments increased the OC and TN content and decreased the^(13)C abundance in the MAOM fraction.More than65%of the tot展开更多
The present study was an effort to understand the amount of litter fall and its subsequent decomposition and quantify the release of available nutrients and soil physicochemical characteristics in plantations of four ...The present study was an effort to understand the amount of litter fall and its subsequent decomposition and quantify the release of available nutrients and soil physicochemical characteristics in plantations of four forest tree species(Lagerstroemia parviflora, Tectona grandis, Shorea robusta and Michelia champaca) in the Chilapatta Reserve Forest of the Cooch Behar Wildlife Division in the Terai zone of West Bengal, India. The most litter(5.61 Mg ha)was produced by T. grandis plantation and the least(4.72 Mg ha) by L. parviflora. The material turnover rate to the soil through decomposition from total litter was fastest during the first quarter of the year and subsequently decreased during the next two quarters. The material turnover rate was only 1 year, which indicates that more than90% of the total litter produced decomposed within a year.The available primary nutrient content in litter varied across the four plantations over the year. The plantations generally did not significantly influence the soil physical characteristics but did significantly influence the availability of primary nutrients and organic carbon at two depths(1–15 and16–30 cm) over the year. The availability of soil primary nutrients in the four plantations also increased gradually from the first quarter of the year to the third quarter and then decreased during the last quarter to the same level as in the first quarter of the year at both depths. The availability for soil organic carbon in the plantations followed a similar trend. The amount of litter produced and the material turnover in the soil in the different plantations differed, influencing the nutrient availability and organic carbon at the plantations. The amount of soil organic carbon was highest for T. grandis(2.52 Mg ha) and lowest for L. parviflora(2.12 Mg ha). Litter is the source of soil organic matter,and more the litter that is produced by the plantations, the higher will be the content and amount of soil organic carbon in the plantation.展开更多
Forest recovery may be influenced by several factors, of which fire is the most critical.However, moderate-and long-term effects of fire on forest recovery are less researched in Northwest China.Thus, the effects of d...Forest recovery may be influenced by several factors, of which fire is the most critical.However, moderate-and long-term effects of fire on forest recovery are less researched in Northwest China.Thus, the effects of different forest recovery time after fire(1917(served as the control), 1974, 1983 and 1995) and fire severities(low, moderate and high) on larch(Larix sibirica Ledeb.) forest were investigated in the Kanas National Nature Reserve(KNNR), Northwest China in 2017.This paper analyzed post-fire changes in stand density, total basal area(TBA), litter mass, soil organic carbon(SOC) and soil nutrients(total nitrogen, total phosphorus and total potassium) with one-way analyses of variance.Results indicate that litter mass, TBA, SOC and soil nutrients increased with increasing recovery time after fire and decreasing fire severity, while the stand density showed an opposite response.The effects of fire disturbance on SOC and soil nutrients decreased with increasing soil depth.Moreover, we found that the time of more than 43 a is needed to recover the litter mass, TBA, SOC and soil nutrients to the pre-fire level.In conclusion, high-severity fire caused the greatest variations in stand structure and soil of larch forest, and low-severity fire was more advantageous for post-fire forest stand structure and soil recovery in the KNNR.Therefore, low-severity fire can be an efficient management mean through reducing the accumulation of forest floor fuel of post-fire forests in the KNNR, Northwest China.展开更多
Water extractable organic carbon (WEOC) and nitrogen (WEON) are two key parameters of soil water extractable organic matter (WEOM). Proper management of manure application rate in combination with tillage and cropping...Water extractable organic carbon (WEOC) and nitrogen (WEON) are two key parameters of soil water extractable organic matter (WEOM). Proper management of manure application rate in combination with tillage and cropping management could maintain appropriate WEOC and WEON concentrations in soils while decreasing the risk of their runoff from cropland and pastures. The objective of this research was to determine the effect of poultry litter (PL) application on WEOC and WEON in soils under different crops, tillage regimes, and grazing strategies. From 2001 to 2012, PL was applied at multiple rates to cultivated fields in a corn-oat/wheat-hay rotation or to pastures grazed by cattle or ungrazed. Soil samples (0 - 15 cm) were analyzed for KCl-extractable mineral N, and WEOC, and WEON contents. In addition, Ultraviolet-visible (UV-vis) and fluorescence spectroscopies were used to characterize WEOC stability. Organic N levels were higher at the high PL application rates. The soil C:N ratio narrowed as the PL application rate increased. However, the soil from pastures which received PL tended to have a wider range of C:N ratios than soil from the cultivated fields, despite identical PL application rates. The spectral analyses indicated that WEOC properties were responsive to management and PL application rate;therefore, this parameter may be used as a guide to provide best management strategy for manure application.展开更多
Grasslands store large stocks of soil organic carbon(SOC) in the subsoil, but our knowledge of belowground processes becomes less robust with depth. Vertically explicit SOC models typically assume that the depth distr...Grasslands store large stocks of soil organic carbon(SOC) in the subsoil, but our knowledge of belowground processes becomes less robust with depth. Vertically explicit SOC models typically assume that the depth distribution of belowground production follows the depth distribution of belowground biomass, but this assumption has not been tested. In addition to the effects of soil temperature and moisture on decomposition, some vertically explicit SOC models implement an intrinsic decrease in belowground decomposition with depth, yet this effect has rarely been observed empirically. We simultaneously measured the depth distributions of belowground biomass, production, and litter decomposition to assess whether belowground biomass depth distributions were suitable predictors of belowground production and whether belowground decomposition decreased with soil profile depth. We found that live and total(live +dead) belowground biomass was distributed relatively more shallowly than total belowground production, and thus total belowground biomass was a biased predictor of the vertical distribution of belowground production. The depth distribution of live roots < 2 mm in diameter was found to be the best predictor of total belowground production depth distribution. Using an intact decay core method,we found that belowground litter decomposition decreased by 49% from 0–10 to 30–40 cm depth, and model-simulated effects of soil temperature and moisture accounted for only 9% of the observed decrease with depth. Vertically explicit SOC models can be improved with more accurate empirical belowground production depth distribution estimates, but depth-specific decomposition rates currently implemented in SOC models are necessary to explain observed decreases in belowground litter decay with depth.展开更多
Plant-derived carbon(C)inputs via foliar litter,root litter and root exudates are key drivers of soil organic C stocks.However,the responses of these three input pathways to climate warming have rarely been studied in...Plant-derived carbon(C)inputs via foliar litter,root litter and root exudates are key drivers of soil organic C stocks.However,the responses of these three input pathways to climate warming have rarely been studied in alpine shrublands.By employing a 3-year warming experiment(increased by 1.3℃),we investigated the effects of warming on the relative C contributions from foliar litter,root litter and root exudates from Sibiraea angustata,a dominant shrub species in an alpine shrubland on the eastern Qinghai-Tibetan Plateau.The soil organic C inputs from foliar litter,root litter and root exudates were 77.45,90.58 and 26.94 g C m^(-2),respectively.Warming only slightly increased the soil organic C inputs from foliar litter and root litter by 8.04 and 11.13 g C m^(-2),but significantly increased the root exudate C input by 15.40 g C m^(-2).Warming significantly increased the relative C contributions of root exudates to total C inputs by 4.6%but slightly decreased those of foliar litter and root litter by 2.5%and 2.1%,respectively.Our results highlight that climate warming may stimulate plant-derived C inputs into soils mainly through root exudates rather than litter in alpine shrublands on the Qinghai-Tibetan Plateau.展开更多
With limited use of inorganic fertilizers on smallholder farms,plant residues could be viable alternatives for soil fertility improvement.This study was conducted to determine how residue quality and decomposition of ...With limited use of inorganic fertilizers on smallholder farms,plant residues could be viable alternatives for soil fertility improvement.This study was conducted to determine how residue quality and decomposition of nine plant species influence soil N availability,microbial biomass,andβ-glucosidase activity during soil fertility improvement.Significant differences in N concentration were found among the species,ranging from 12.2 g kg-1 in Zea mays to 39.2 g kg-1 in Baphia nitida.The C/N ratio was the highest in Z.mays(34.4),whereas lignin and polyphenol concentrations were the greatest in Acacia auriculiformis.The highest decomposition rate(0.251%per day)occurred in Tithonia diversifolia,and the lowest in A.auriculiformis,Albizia zygia,B.nitida,and Z.mays,with the half-lives of 28-56 d.Between 80%and 89%of N,P,K,Ca,and Mg were released from T.diversifolia in 7 d,compared with over 70%retention in A.auriculiformis,B.nitida,and Z.mays.The decomposition and nutrient release half-lives of Gliricidia sepium,Leucaena leucocephala,Azadirachta indica,and Senna spectabilis were less than 14 d.Soil mineral N,microbial biomass,andβ-glucosidase activity increased under all treatments,with T.diversifolia having the greatest effect.While N mineralization occurred in all of the species throughout the experiment,an initial N immobilization was recorded in the A.zy.gia,B.nitida,A.auriculiformis,and Z.mays treatments for up to 14 d.Decomposition and nutrient release rates,mineral N,soil microbial biomass,andβ-glucosidase activity were dependent on residue quality,and P and lignin levels,the lignin/N ratio,and the(lignin+polyphenol)/N ratio had the most significant effects(P≤0.05).展开更多
Leaf litter input from riparian landscapes has been identified as both a major energy flow to stream ecosystems and as a food source for stream macroinvertebrates. In this study the benthic macroinvertebrate community...Leaf litter input from riparian landscapes has been identified as both a major energy flow to stream ecosystems and as a food source for stream macroinvertebrates. In this study the benthic macroinvertebrate community was used to evaluate the decomposition of organic matter in river systems. The aim of this work was to study the decomposition of organic matter using the benthic macroinvertebrate colonization. The research was developed over five months (January 2011 to May 2011) in four different sites, distributed along the River Ferreira terminal area, northern Portugal. A litter bag experiment was used to examine the role of macroinvertebrate communities in the processing of organic material on the river. Litter bags were placed in the water and collected every 7, 15, 30, 60, 90 and 120 days. In litter bags was observed a high abundance of Oligochaeta and Chironomidae, which are characterized by being detritivorous-herbivores and filtering collectors, respectively, indicating the benthic macroinvertebrate more involved on the decomposition of organic matter. These results contributed to increase current knowledge about benthic macroinvertebrate communities and may serve as incentive for future research works.展开更多
The effects of supplementing a blend of organic acids (OA) and a lactic acid bacteria (LAB) based-probiotic on egg to chick weight loss (%) and Salmonella spp. recovery counts in the litter of commercial broiler breed...The effects of supplementing a blend of organic acids (OA) and a lactic acid bacteria (LAB) based-probiotic on egg to chick weight loss (%) and Salmonella spp. recovery counts in the litter of commercial broiler breeders were examined in three independent trials during the years 2013, 2014 and 2015. In each trial, ten thousand birds were divided into two groups of 5000 birds (4500 females and 500 males in each group): Control non-treated group, receiving regular water or treated group, receiving OA and probiotic in the drinking water from 25 to 35 weeks of age. During the ten weeks of evaluation, one thousand fertile eggs or hatched chickens in each trial respectively, were evaluated to obtained, hatching set weight, transferred egg weight, and hatching chick weight, to estimate the difference between egg to chick weight loss (%). Besides, in trial 2 (2014) and trial 3 (2015), litter samples were collected to evaluate Salmonella spp. counts. The supplementation of OA and probiotic during ten consecutive weeks significantly decreased the egg to chick weight loss (%) when compared with the control non-treated groups in all three trials evaluated. Interestingly, at the end of the trials 2 and 3, no counts of Salmonella spp. in the litter were detected. In contrast, control-non treated groups resulted in 4.30 and 4.24 Log10 of Salmonella spp. in trials two and three respectively. The results of the present study suggest that supplementation of OA and a LAB-probiotic for ten consecutive weeks decrease the egg to chick weight loss (%) and reduce Salmonella spp. counts in the litter of commercial broiler breeders. Higher initial body weight in broiler chickens and reduction of Salmonella spp., clearly justify the use of the combination of these products, as alternatives to antibiotics.展开更多
基金funded by the National Key Research and Development Program of China (2017YFC0504601)the Science and Technology Service Network Initiative of Chinese Academy of Sciences (KFJ-STS-ZDTP-036)the National Natural Science Foundation of China (41671513)
文摘The lack of clarity of how natural vegetation restoration influences soil organic carbon(SOC) content and SOC components in soil aggregate fractions limits the understanding of SOC sequestration and turnover in forest ecosystems.The aim of this study was to explore how natural vegetation restoration affects the SOC content and ratio of SOC components in soil macroaggregates(>250 μm), microaggregates(53–250 μm), and silt and clay(<53 μm) fractions in 30-, 60-, 90-and 120-year-old Liaodong oak(Quercus liaotungensis Koidz.) forests, Shaanxi, China in 2015.And the associated effects of biomasses of leaf litter and different sizes of roots(0–0.5, 0.5–1.0, 1.0–2.0 and >2.0 mm diameter) on SOC components were studied too.Results showed that the contents of high activated carbon(HAC), activated carbon(AC) and inert carbon(IC) in the macroaggregates, microaggregates and silt and clay fractions increased with restoration ages.Moreover, IC content in the microaggregates in topsoil(0–20 cm) rapidly increased;peaking in the 90-year-old restored forest, and was 5.74 times higher than AC content.In deep soil(20–80 cm), IC content was 3.58 times that of AC content.Biomasses of 0.5–1.0 mm diameter roots and leaf litter affected the content of aggregate fractions in topsoil, while the biomass of >2.0 mm diameter roots affected the content of aggregate fractions in deep soil.Across the soil profiles, macroaggregates had the highest capacity for HAC sequestration.The effects of restoration ages on soil aggregate fractions and SOC content were less in deep soil than in topsoil.In conclusion, natural vegetation restoration of Liaodong oak forests improved the contents of SOC, especially IC within topsoil and deep soil.The influence of IC on aggregate stability was greater than the other SOC components, and the aggregate stability was significantly affected by the biomasses of litter, 0.5–1.0 mm diameter roots in topsoil and >2.0 mm diameter roots in deep soil.Natural vegetation restoration of Liaodong oak forests pr
基金supported by the GuangDong Basic and Applied Basic Research Foundation(2022A1515110439)the National Natural Science Foundation of China(32101393)+1 种基金China Postdoctoral Science Foundation(2023M7339832023M743547)。
文摘Background:Forest soils in tropical and subtropical areas store a significant amount of carbon.Recent framework to assess soil organic matter(SOM)dynamics under evolving global conditions suggest that dividing bulk SOM into particulate and mineral-associated organic matter(POM vs.MAOM)is a promising method for identifying how SOM contributes to reducing global warming.Soil macrofauna,earthworms,and millipedes have been found to play an important role in facilitating SOM processes.However,how these two co-existing macrofaunae impac the litter decomposition process and directly impact the formation of POM and MAOM remains unclear.Methods:Here,we set up a microcosm experiment,which consisted of 20 microcosms with four treatments earthworm and litter addition(E),millipedes and litter addition(M),earthworm,millipedes,and litter addition(E+M),and control(only litter addition)in five replicates.The soil and litter were sterilized prior to beginning the incubation experiment to remove any existing microbes.After incubating the samples for 42 days,the litte properties(mass,C,and N contents),soil physicochemical properties,as well as the C and N contents,and POM and MAOM^(13)C abundance in the 0–5 and 5–10 cm soil layers were measured.Finally,the relative influences o soil physicochemical and microbial properties on the distribution of C and N in the soil fractions were analyzed Results:The litter mass,C,and N associated with all four treatments significantly decreased after incubation especially under treatment E+M(litter mass:-58.8%,litter C:-57.0%,litter N:-75.1%,respectively),while earthworm biomass significantly decreased under treatment E.Earthworm or millipede addition alone showed no significant effects on the organic carbon(OC)and total nitrogen(TN)content in the POM fraction,but join addition of both significantly increased OC and TN regardless of soil depth.Importantly,all three macrofauna treatments increased the OC and TN content and decreased the^(13)C abundance in the MAOM fraction.More than65%of the tot
文摘The present study was an effort to understand the amount of litter fall and its subsequent decomposition and quantify the release of available nutrients and soil physicochemical characteristics in plantations of four forest tree species(Lagerstroemia parviflora, Tectona grandis, Shorea robusta and Michelia champaca) in the Chilapatta Reserve Forest of the Cooch Behar Wildlife Division in the Terai zone of West Bengal, India. The most litter(5.61 Mg ha)was produced by T. grandis plantation and the least(4.72 Mg ha) by L. parviflora. The material turnover rate to the soil through decomposition from total litter was fastest during the first quarter of the year and subsequently decreased during the next two quarters. The material turnover rate was only 1 year, which indicates that more than90% of the total litter produced decomposed within a year.The available primary nutrient content in litter varied across the four plantations over the year. The plantations generally did not significantly influence the soil physical characteristics but did significantly influence the availability of primary nutrients and organic carbon at two depths(1–15 and16–30 cm) over the year. The availability of soil primary nutrients in the four plantations also increased gradually from the first quarter of the year to the third quarter and then decreased during the last quarter to the same level as in the first quarter of the year at both depths. The availability for soil organic carbon in the plantations followed a similar trend. The amount of litter produced and the material turnover in the soil in the different plantations differed, influencing the nutrient availability and organic carbon at the plantations. The amount of soil organic carbon was highest for T. grandis(2.52 Mg ha) and lowest for L. parviflora(2.12 Mg ha). Litter is the source of soil organic matter,and more the litter that is produced by the plantations, the higher will be the content and amount of soil organic carbon in the plantation.
基金supported by the National Natural Science Foundation of China (31570634)the Project of Xinjiang Agricultural Vocational College (XJNZYKJ201712)
文摘Forest recovery may be influenced by several factors, of which fire is the most critical.However, moderate-and long-term effects of fire on forest recovery are less researched in Northwest China.Thus, the effects of different forest recovery time after fire(1917(served as the control), 1974, 1983 and 1995) and fire severities(low, moderate and high) on larch(Larix sibirica Ledeb.) forest were investigated in the Kanas National Nature Reserve(KNNR), Northwest China in 2017.This paper analyzed post-fire changes in stand density, total basal area(TBA), litter mass, soil organic carbon(SOC) and soil nutrients(total nitrogen, total phosphorus and total potassium) with one-way analyses of variance.Results indicate that litter mass, TBA, SOC and soil nutrients increased with increasing recovery time after fire and decreasing fire severity, while the stand density showed an opposite response.The effects of fire disturbance on SOC and soil nutrients decreased with increasing soil depth.Moreover, we found that the time of more than 43 a is needed to recover the litter mass, TBA, SOC and soil nutrients to the pre-fire level.In conclusion, high-severity fire caused the greatest variations in stand structure and soil of larch forest, and low-severity fire was more advantageous for post-fire forest stand structure and soil recovery in the KNNR.Therefore, low-severity fire can be an efficient management mean through reducing the accumulation of forest floor fuel of post-fire forests in the KNNR, Northwest China.
文摘Water extractable organic carbon (WEOC) and nitrogen (WEON) are two key parameters of soil water extractable organic matter (WEOM). Proper management of manure application rate in combination with tillage and cropping management could maintain appropriate WEOC and WEON concentrations in soils while decreasing the risk of their runoff from cropland and pastures. The objective of this research was to determine the effect of poultry litter (PL) application on WEOC and WEON in soils under different crops, tillage regimes, and grazing strategies. From 2001 to 2012, PL was applied at multiple rates to cultivated fields in a corn-oat/wheat-hay rotation or to pastures grazed by cattle or ungrazed. Soil samples (0 - 15 cm) were analyzed for KCl-extractable mineral N, and WEOC, and WEON contents. In addition, Ultraviolet-visible (UV-vis) and fluorescence spectroscopies were used to characterize WEOC stability. Organic N levels were higher at the high PL application rates. The soil C:N ratio narrowed as the PL application rate increased. However, the soil from pastures which received PL tended to have a wider range of C:N ratios than soil from the cultivated fields, despite identical PL application rates. The spectral analyses indicated that WEOC properties were responsive to management and PL application rate;therefore, this parameter may be used as a guide to provide best management strategy for manure application.
基金funded through a grant from the Wisconsin Focus on Energy Environmental and Economic Research and Development Program awarded to the second author M.E.Dornbush,K.Fermanich,J.Stoll,and P.Baumgart through the Environmental Management and Business Institute at the University of Wisconsin-Green Bay,USAfunded through the Barbra Hauxhurst Cofrin Graduate Research Fellowship in Environmental Science and Policy at the University of Wisconsin-Green Bay,USA
文摘Grasslands store large stocks of soil organic carbon(SOC) in the subsoil, but our knowledge of belowground processes becomes less robust with depth. Vertically explicit SOC models typically assume that the depth distribution of belowground production follows the depth distribution of belowground biomass, but this assumption has not been tested. In addition to the effects of soil temperature and moisture on decomposition, some vertically explicit SOC models implement an intrinsic decrease in belowground decomposition with depth, yet this effect has rarely been observed empirically. We simultaneously measured the depth distributions of belowground biomass, production, and litter decomposition to assess whether belowground biomass depth distributions were suitable predictors of belowground production and whether belowground decomposition decreased with soil profile depth. We found that live and total(live +dead) belowground biomass was distributed relatively more shallowly than total belowground production, and thus total belowground biomass was a biased predictor of the vertical distribution of belowground production. The depth distribution of live roots < 2 mm in diameter was found to be the best predictor of total belowground production depth distribution. Using an intact decay core method,we found that belowground litter decomposition decreased by 49% from 0–10 to 30–40 cm depth, and model-simulated effects of soil temperature and moisture accounted for only 9% of the observed decrease with depth. Vertically explicit SOC models can be improved with more accurate empirical belowground production depth distribution estimates, but depth-specific decomposition rates currently implemented in SOC models are necessary to explain observed decreases in belowground litter decay with depth.
基金supported by the Open Project from the Ecological Security and Protection Key Laboratory of Sichuan Province(ESP1904,ESP2102)the Doctoral Scientific Research Foundation of China West Normal University(18Q047)the Scientific Research Innovation Team Project of China West Normal University(CXTD2020-4).
文摘Plant-derived carbon(C)inputs via foliar litter,root litter and root exudates are key drivers of soil organic C stocks.However,the responses of these three input pathways to climate warming have rarely been studied in alpine shrublands.By employing a 3-year warming experiment(increased by 1.3℃),we investigated the effects of warming on the relative C contributions from foliar litter,root litter and root exudates from Sibiraea angustata,a dominant shrub species in an alpine shrubland on the eastern Qinghai-Tibetan Plateau.The soil organic C inputs from foliar litter,root litter and root exudates were 77.45,90.58 and 26.94 g C m^(-2),respectively.Warming only slightly increased the soil organic C inputs from foliar litter and root litter by 8.04 and 11.13 g C m^(-2),but significantly increased the root exudate C input by 15.40 g C m^(-2).Warming significantly increased the relative C contributions of root exudates to total C inputs by 4.6%but slightly decreased those of foliar litter and root litter by 2.5%and 2.1%,respectively.Our results highlight that climate warming may stimulate plant-derived C inputs into soils mainly through root exudates rather than litter in alpine shrublands on the Qinghai-Tibetan Plateau.
基金fully funded by the International Foundation for Science (IFS) in Stockholmsupported by the West Africa Regional Program of the CGIAR Research Program on Climate Change, Agriculture, and Food Security (CCAFS) in Bamako, Mali
文摘With limited use of inorganic fertilizers on smallholder farms,plant residues could be viable alternatives for soil fertility improvement.This study was conducted to determine how residue quality and decomposition of nine plant species influence soil N availability,microbial biomass,andβ-glucosidase activity during soil fertility improvement.Significant differences in N concentration were found among the species,ranging from 12.2 g kg-1 in Zea mays to 39.2 g kg-1 in Baphia nitida.The C/N ratio was the highest in Z.mays(34.4),whereas lignin and polyphenol concentrations were the greatest in Acacia auriculiformis.The highest decomposition rate(0.251%per day)occurred in Tithonia diversifolia,and the lowest in A.auriculiformis,Albizia zygia,B.nitida,and Z.mays,with the half-lives of 28-56 d.Between 80%and 89%of N,P,K,Ca,and Mg were released from T.diversifolia in 7 d,compared with over 70%retention in A.auriculiformis,B.nitida,and Z.mays.The decomposition and nutrient release half-lives of Gliricidia sepium,Leucaena leucocephala,Azadirachta indica,and Senna spectabilis were less than 14 d.Soil mineral N,microbial biomass,andβ-glucosidase activity increased under all treatments,with T.diversifolia having the greatest effect.While N mineralization occurred in all of the species throughout the experiment,an initial N immobilization was recorded in the A.zy.gia,B.nitida,A.auriculiformis,and Z.mays treatments for up to 14 d.Decomposition and nutrient release rates,mineral N,soil microbial biomass,andβ-glucosidase activity were dependent on residue quality,and P and lignin levels,the lignin/N ratio,and the(lignin+polyphenol)/N ratio had the most significant effects(P≤0.05).
文摘Leaf litter input from riparian landscapes has been identified as both a major energy flow to stream ecosystems and as a food source for stream macroinvertebrates. In this study the benthic macroinvertebrate community was used to evaluate the decomposition of organic matter in river systems. The aim of this work was to study the decomposition of organic matter using the benthic macroinvertebrate colonization. The research was developed over five months (January 2011 to May 2011) in four different sites, distributed along the River Ferreira terminal area, northern Portugal. A litter bag experiment was used to examine the role of macroinvertebrate communities in the processing of organic material on the river. Litter bags were placed in the water and collected every 7, 15, 30, 60, 90 and 120 days. In litter bags was observed a high abundance of Oligochaeta and Chironomidae, which are characterized by being detritivorous-herbivores and filtering collectors, respectively, indicating the benthic macroinvertebrate more involved on the decomposition of organic matter. These results contributed to increase current knowledge about benthic macroinvertebrate communities and may serve as incentive for future research works.
文摘The effects of supplementing a blend of organic acids (OA) and a lactic acid bacteria (LAB) based-probiotic on egg to chick weight loss (%) and Salmonella spp. recovery counts in the litter of commercial broiler breeders were examined in three independent trials during the years 2013, 2014 and 2015. In each trial, ten thousand birds were divided into two groups of 5000 birds (4500 females and 500 males in each group): Control non-treated group, receiving regular water or treated group, receiving OA and probiotic in the drinking water from 25 to 35 weeks of age. During the ten weeks of evaluation, one thousand fertile eggs or hatched chickens in each trial respectively, were evaluated to obtained, hatching set weight, transferred egg weight, and hatching chick weight, to estimate the difference between egg to chick weight loss (%). Besides, in trial 2 (2014) and trial 3 (2015), litter samples were collected to evaluate Salmonella spp. counts. The supplementation of OA and probiotic during ten consecutive weeks significantly decreased the egg to chick weight loss (%) when compared with the control non-treated groups in all three trials evaluated. Interestingly, at the end of the trials 2 and 3, no counts of Salmonella spp. in the litter were detected. In contrast, control-non treated groups resulted in 4.30 and 4.24 Log10 of Salmonella spp. in trials two and three respectively. The results of the present study suggest that supplementation of OA and a LAB-probiotic for ten consecutive weeks decrease the egg to chick weight loss (%) and reduce Salmonella spp. counts in the litter of commercial broiler breeders. Higher initial body weight in broiler chickens and reduction of Salmonella spp., clearly justify the use of the combination of these products, as alternatives to antibiotics.
