RESUMO
Vegetation restoration can effectively enhance soil quality and soil organic carbon (SOC) sequestration. In this study, the distribution characteristics of soil nutrients and SOC along soil profile (0-100 cm), and their responses to restoration years (16, 28, 38 years) were studied in Caragana korshinskii plantations in the southern mountainous area of Ningxia, compared with cropland and natural grassland. The results showed that: 1) the contents of SOC, soil total nitrogen (TN), total phosphorus (TP), particulate organic carbon (POC), mineral-associated organic carbon (MAOC) and the proportion of particulate organic carbon to total organic carbon (POC/SOC) all decreased with increasing soil depth. The ratio of mineral-associated organic carbon to total organic carbon (MAOC/SOC) exhibited an opposite trend. 2) The contents of SOC, TN, TP, C:P, N:P, POC and MAOC gra-dually decreased as the restoration years increased. However, the C:N ratio showed no significant change. The POC/SOC ratio initially increased and then decreased, while the MAOC/SOC ratio decreased initially and then increased. 3) In three different types of vegetation, POC, MAOC, and SOC showed a highly significant positive linear correlation, with the increase in SOC mainly depended on the increase in MAOC. The SOC, TN, TP, POC and MAOC contents in natural grassland and C. korshinskii plantations were significantly higher than those in cropland. In conclusion, soil nutrients and POC and MAOC contents of C. korshinskii plantations gradually decreased with the increases in restoration years. However, when compared with cropland, natural grassland and C. korshinskii plantations demonstrated a greater capacity to maintain and enhance soil nutrient and carbon storage.
Assuntos
Caragana , Carbono , Florestas , Nitrogênio , Compostos Orgânicos , Fósforo , Solo , China , Solo/química , Carbono/análise , Caragana/crescimento & desenvolvimento , Nitrogênio/análise , Fósforo/análise , Compostos Orgânicos/análise , Nutrientes/análise , Recuperação e Remediação Ambiental/métodos , Sequestro de Carbono , EcossistemaRESUMO
Microorganisms are essential actors in the biogeochemical cycling of elements within terrestrial ecosystems, with significant influences on soil health, food security, and global climate change. The contribution of microbial anabolism-induced organic compounds is a non-negligible factor in the processes associated with soil carbon (C) storage and organic matter preservation. In recent years, the conceptual framework of soil microbial carbon pump (MCP), with a focus on microbial metabolism and necromass generation process, has gained widespread attention. It primarily describes the processes of soil organic C formation and stabilization driven by the metabolic activities of soil heterotrophic microorganisms, representing an important mechanism and a focal point in current research on terrestrial C sequestration. Here, we reviewed the progress in this field and introduced the soil MCP conceptual framework 2.0, which expands upon the existing MCP model by incorporating autotrophic microbial pathway for C sequestration and integrating the concept of soil mineral C pump. These advancements aimed to enrich and refine our understanding of microbial-mediated terrestrial ecosystem C cycling and sequestration mechanisms. This refined framework would provide theoretical support for achieving China's "dual carbon" goals.
Assuntos
Carbono , Ecossistema , Carbono/química , Solo/química , Microbiologia do Solo , Ciclo do Carbono , Sequestro de CarbonoRESUMO
Soil organic carbon (SOC) is the core component of terrestrial carbon (C) sink. Exploring the transformation and stabilization mechanism of SOC is key to understand the function of terrestrial C sink which copes with climate change. The traditional perspective is that plant residues are the initial source of SOC. The new concept of "soil microbial C pump" emphasizes that the synthesized products of soil microbial assimilation are important contributors to the stable SOC. This provides a new insight to the sequestration mechanism of SOC. Due to the complex and variable decomposition process of plant residues and the high heterogeneity of microbial residues, the transformation and stabilization mechanism of plant residues and microbial residues into SOC is still unclear. We reviewed research progress in plant and microbial residues, and introduced the characterization methods of quantification and transformation of plant residues and microbial residues, and also summarized the new findings on the transformation of plant and microbial residues into SOC. We further discussed the contribution and driving factors of microbial and plant-derived C to SOC. Finally, we prospected the future development direction and research focus in this field. This review would provide the scientific reference for the research of soil C sequestration in terrestrial ecosystem.
Assuntos
Ecossistema , Solo , Solo/química , Carbono , Sequestro de Carbono , Celulose , Plantas , Microbiologia do SoloRESUMO
Microbial necromass, an important and stable source of soil organic carbon (SOC), is an important index to evaluate the contribution of microorganisms to SOC transformation and accumulation. It is not clear about the accumulation of microbial necromass in deep soil layer and its contribution to SOC during the restoration process of Caragana korshinskii forests. Combined with the biomarker method, we investigated the carbon contents of bacte-rial, fungal, and microbial necromass in the soil profiles (0-100 cm) of C. korshinskii forests in 16, 28, and 38 years of restoration, with natural grassland as control. We further examined the contribution of microbial necromass to soil organic carbon. The results showed that: 1) Along the soil profile (0-100 cm), the contents of fungal necromass carbon (FNC), bacterial necromass carbon (BNC), and microbial necromass carbon (MNC) significantly decreased with increasing soil depth in natural grassland and C. korshinskii forests. Except for the significant decrease in FNC/SOC, BNC/SOC, and MNC/SOC in the soil of C. korshinskii forests in 38 years of restoration, FNC/SOC and MNC/SOC generally showed an increasing trend followed by a decreasing trend in other plots, while BNC/SOC gradually decreased. 2) With the increases of restoration years, the contents of FNC, BNC, and MNC significantly decreased in C. korshinskii forests. FNC/SOC and MNC/SOC showed an overall increasing trend followed by a decreasing trend, while BNC/SOC gradually decreased. 3) The average contribution of microbial necromass carbon to SOC was highest in C. korshinskii forests in 28 years of restoration (35.0%), followed by C. korshinskii forests in 16 years of restoration (33.5%), natural grassland (31.0%), and C. korshinskii forests in 38 years of restoration (28.6%). In conclusion, when the restoration years of C. korshinskii forests are 16, the contents of microbial necromass carbon and their contributions to SOC are higher compared to natural grassland, which are beneficial for SOC sequestration.
Assuntos
Caragana , Solo , Carbono/análise , Florestas , China , Microbiologia do SoloRESUMO
As the main participants of ecosystem functions, the response of microorganisms to variations in soil moisture caused by the changes in precipitation amounts should be quantified to evaluate the impact of climate change on semi-arid ecosystems. For this purpose, a two-year simulation of the changes in the rainfall patterns was conducted on the Loess Plateau, and five precipitation treatments (80% and 40% decrease in precipitation, D80, D40; natural precipitation, NP; 40% and 80% increase in precipitation, I40, I80) were set up. The results showed that: â Compared with NP, the carbon-to-nitrogen ratio (C/N) was lower in DP80 or IP80, while it reached the maximum value in I40. The mean C/N value of the 0-20 cm soil layer was 10.76. The microbial biomass carbon to microbial biomass nitrogen ratio (MBC/MBN) varied significantly with the soil layer in the treatments of D80 and I80, and the maximum value was 14.15 in D80. â¡ In the grassland soil naturally growing on the Loess Plateau, at the phylum level, the dominant phyla were Actinobacteria, Proteobacteria, Chloroflexi, and Acidobacteria. At the class level, Actinobacteria, Acidobacteria, α-Proteobacteria, and Thermomicrobia were predominant. ⢠RDA analysis showed that changes in soil dissolve organic carbon (DOC), dissolved organic nitrogen (DON), elemental carbon (EC), and pH values were the main factors affecting the distribution of soil bacteria under the five precipitation treatments in the study area. Overall, 80% increase or decrease in precipitation has a significant impact on soil active organic carbon content and bacterial abundance, especially D80. In conclusion, drought or extreme precipitation may considerably change the active organic matter content and bacterial community diversity and abundance in the soils of the Loess Plateau.
Assuntos
Ecossistema , Solo , Carbono/análise , China , Pradaria , Humanos , Nitrogênio/análise , Microbiologia do SoloRESUMO
Decades of ecological restoration on the Loess Plateau has achieved significant on-site benefits to reduce soil erosion and improve soil quality, with remarkable off-site effects of reducing sediment delivery to Yellow River. However, regional forest community succession is still far from being adequately developed. The Ziwuling forest region and its highly developed forest community, as an advanced eco-zone, can lend practical experience to other regions on the Loess Plateau and help to identify the most suitable tree species for a better regional restoration in the future. With the aim to systematically understand the potential effects of typical local tree species to soil properties, three typical and well-established artificial forests in the Ziwuling region, Robinia pseudoacacia, Pinus tabuliformis and Platycladus orientalis were investigated in this study, with the climax community Quercus wutaishanica as a reference. All the four forest type had comparable stand age (25 years). Soil samples from 0-20 cm layers were collected from those four plantations. The soil microbial biomass (carbon and nitrogen), soil enzyme (invertase, urease and alkaline phosphatase) activities and their correlations were measured and analyzed. The results showed that: 1) soil invertase activity ranged from 16.94 to 64.49 mg·g-1·24 h-1, the soil urease activity from 0.15 to 0.26 mg·g-1·24 h-1, and the alkaline phosphatase activity from 0.65 to 1.23 mg·g-1·24 h-1. The activities of those three enzymes were significantly higher in the P. orientalis soil that in the R. pseudoacacia and P. tabuliformis soils. The geometric average values in the P. orientalis soil were even greater than that in the Q. wutaishanica soil. 2) The soil microbial biomass carbon and nitrogen varied from 247.37 to 529.84 mg·kg-1 and 41.48 to 77.91 mg·kg-1, respectively. Both of them were significantly greater in the P. orientalis soil than that in the R. pseudoacacia and P. tabu-liformis soils. Even though the soil microbial biomass carbon in the P. orientalis soil remained lower than that in the Q. wutaishanica soil, its soil microbial biomass nitrogen was greater than in the Q. wutaishanica soil. 3) The dissolved organic carbon and nitrogen in the P. tabuliformis soil were much greater than that in other species, even greater than their own soil microbial biomass carbon and nitrogen. Such a result indicated that dissolved organic matter might play a more important role in providing plant available nutrients than microbial biomass in the P. tabuliformis soil. 4) The microbial biomass carbon and nitrogen were significantly positively correlated with the total organic carbon and the total nitrogen, particularly for the R. pseudoacacia and P. tabuliformis soils. There were significantly positive relationships between the soil invertase activity, urease activity and alkaline phosphatase activity, and their soil organic carbon, total nitrogen and total phosphorus contents. 5) Based on the results of principal component analysis, we concluded that the artificial forests types had obvious effects on soil microbial carbon and nitrogen, soil organic carbon, total nitrogen, the ratio of carbon to phosphorus, the ratio of nitrogen to phosphorus and urease activity. Overall, our findings suggested that P. orientalis is better than R. pseudoacacia and P. tabuliformis in term of improving soil properties in the south forest zone on the Chinese Loess Plateau.
Assuntos
Florestas , Microbiologia do Solo , Biomassa , Carbono , China , Nitrogênio , Fósforo , Pinus , Robinia , Solo , UreaseRESUMO
The objectives of this study were to explore the effects of vegetation type, topographic features and their combined effects on soil microbial biomass stoichiometry, so as to better understand the interaction of soil, soil microbes and nutrient cycling under different vegetation types in the hilly-gully region of the Loess Plateau. Soils from three vegetation zones (forest zone, forest-steppe and steppe) and five slope positions (south/north backslope, south/north shoulder and summit) were chosen and the effects of vegetation types and topography features on soil and C:N:P ratios in soil microbial biomass were investigated in this study. The results showed that, among the five slope positions, the highest concentrations of soil and soil microbial biomass C, N, P were found at the backslope position and the north-facing slope. The effects of vegetation types on soil and soil microbial biomass C, N and P in the two soil layers were significantly different, whereas the effects of slope aspect and positions were only numerically different. As for different soil layers, the topsoil (0-10 cm) was more affected by slope aspect, while the subsoil (10-20 cm) was more influenced by slop position. While the effects of vegetation type on soil C:N, C:P and N:P and soil microbial biomass C:N, C:P were significant, slope aspect and slope position only influenced soil C:P and N:P. Consequently, on the Loess Plateau, the effects of vegetation type on soil and soil microbial biomass C, N, P were stronger than those of the topographic features. The standardized major axis tests showed that C:N:P stoichiometry in soil microbes was well-constrained, especially in the steppe zone. The soil microbial biomass N:P might be used as a useful tool to assess nutrient limitation of ecosystem processes in terrestrial ecosystems. If combined with plant leaf N:P, they could provide more accurate information to estimate the nutrient limitation of fragile ecosystem in hilly-gully region of the Loess Plateau.
Assuntos
Ecossistema , Microbiologia do Solo , Biomassa , China , Nitrogênio , Fósforo , SoloRESUMO
This study was conducted in the forest, forest-steppe and steppe vegetation zones along the Yanhe River Basin, where the leaf and litter samples from four dominant herbaceous plants including Lespedeza davurica, Stipa bungeana, Artemisia sacrorum, Artemisia giraldii were taken. By measuring the concentrations of carbon (C), nitrogen (N), phosphorus (P) and potassium (K), we measured the concentrations and their ratios to explore the limit and resorption of nutrient in the herbaceous plants. The results showed that the leaf N/P of four herbaceous plants was all lower than 14, suggesting their growth was mainly limited by N content. Except for L. davurica, the mean nutrient resorption efficiency of K, N and P in the other three plants was 79.9%, 48.7% and 32.5%, respectively. The higher nutrient resorption efficiency and K concentration in the leaf were beneficial for soil water competition of A. sacrorum and A. giraldii. The litter C/N in A. sacrorum was significantly lower than that in S. bungeana and A. giraldii, which was easy to decompose to benefit the nutrient recycling. This resulted in the wide distribution of A. sacrorum in the three vegetation areas.
Assuntos
Ecossistema , Folhas de Planta , Poaceae , China , Nitrogênio , Fósforo , SoloRESUMO
Carbon (C), nitrogen (N) and phosphorus (P) stoichiometry from the aboveground parts of plants, roots, plant litter and soils, as well as their relationships were studied in grassland under four distinct types of vegetation recovery including natural grassland, grassland with shrubs, grassland after grazing exclusion, and abandoned cropland in Yunwu Mountain, China. The results showed that there was significant correlation among the ecological stoichiometric characteristics of soils with the aboveground parts and roots. The relation between the aboveground parts and roots was closer in P concentration than in N concentration. The linkage of plants and soils was closer in N concentration than in P concentration. The ecological stoichiometric relationships between soils and litter as well as between roots and litter were weak. There was no significant difference between the aboveground parts and roots in total C and N storages among four distinct recovery methods. How-ever, the P storage differed greatly among the four recovery types with the maximum of 0.49 g·m-2 in the abandoned cropland and the minimum value of 0.29 g·m-2 in the grassland after grazing exclusion. Grazing prohibition duration had minor effects on ecological stoichiometric characteristics. The 12-year-abandoned cropland had lower soil organic C and total N concentration (9.98 and 1.07 g·kg-1, respectively) compared with natural grasslands (14.27 and 1.55 g·kg-1, respectively), and this difference of ecological stoichiometric characteristics was caused by the high P concentration in abandoned cropland. The roots N and P concentrations were the lowest in natural grassland with 6.25 and 0.57 g·kg-1, respectively, due to the greatest amount of root biomass. The N and P concentrations in the grassland with shrubs were relatively lower in the aboveground parts(12.77 and 0.98 g·kg-1,respectively) while relatively higher in roots (9.30 and 0.77 g·kg-1, respectively). Overall, the plant composition was the key factor that influenced the ecological stoichiome-tric characteristics of plant communities. The distinctions of the ecological stoichiometric characteristics among different restoration types decreased with the increasing Sorensen index.
Assuntos
Pradaria , Nitrogênio , Solo , Biomassa , Carbono , China , PlantasRESUMO
Choosing the soils under different vegetation recovery of Heidaigou dump as the research objects, we mainly analyzed their basic physical and chemical properties and enzyme activities with the method of Analysis of Variance as well as their relations using Pearson correlation analysis and path analysis hoping to uncover the driving factors of the differences between soil enzyme activities under different vegetation restoration, and provide scientific suggestions for the plant selection as well as make a better evaluation to the reclamation effect. The results showed that: (1) Although the artificial vegetation restoration improved the basic physical and chemical properties of the soils while increasing their enzyme activities to a certain extent, the soil conditions still did not reach the level of the natural grassland; (2) Contents of soil organic carbon (SOC) and soil total nitrogen (TN) of the seabuckthorns were the nearest to those of the grassland, which reached 54. 22% and 70. 00% of those of the grassland. In addition, the soil bulk density of the seabuckthorns stand was 17. 09% lower than the maximum value of the amorpha fruitcosa land. The SOC and TN contents as well as the bulk density showed that seabuckthorns had advantages as the species for land reclamation of this dump; Compared with the seabuckthorn, the pure poplar forest had lower contents of SOC and TN respectively by 35.64% and 32.14% and displayed a 16.79% higher value of soil bulk density; (3) The activities of alkaline phosphotase under different types of vegetation rehabilitation had little variation. But soil urease activities was more sensitive to reflect the effects of vegetation restoration on soil properties; (4) Elevation of the SOC and TN turned out to be the main cause for soil fertility restoration and increased biological activities of the dump.
Assuntos
Carvão Mineral , Recuperação e Remediação Ambiental , Enzimas/química , Mineração , Solo/química , Carbono/análise , Florestas , Pradaria , Hippophae , Nitrogênio/análise , PopulusRESUMO
With the method of litter bags, the characteristics of soil enzyme activities, soil microbial diversity at later stage of decomposition, and the relationships between soil enzyme activity and initial soil property were investigated in the process of stem and leaf decomposition of three typical herbs, i.e., Stipa bungeana, Artemisia sacrorum and Thymus mongolicus in the south Ningxia loess hilly region, Northwest China. The results showed that soil enzyme activity increased under different treatments after 480 d during stem and leaf decomposition. Soil sucrose activity (32.40 mg·g-1·24 h-1) and alkaline phosphatase activity (1.99 mg·g-1·24 h-1) were the highest in S. bungeana treatment. Soil urease activity (2.66 mg·g-1·24 h-1) was the highest in T. mongolicus treatment, and soil cellulase activity (1.42 mg·g-1·72 h-1) was the highest in A. sacrorum treatment. Soil cellulose activity at later stage of decomposition had significant positive correlation with initial microbial biomass carbon of soil. Soil cellulose activity at later stage of decomposition had significant negative correlation with initial nitrate nitrogen content of soil. Ace index, Chao index and Shannon index of soil bacteria and fungi in plant tissue addition treatments were higher than in the control. However, Simpson index was opposed. The stem and leaf decomposition significantly promoted the abundance and diversity of soil bacteria and fungi, accelerated the decomposition rate of stems and leaves, and promoted the cycle and transformation of soil nutrients.
Assuntos
Enzimas/análise , Folhas de Planta , Caules de Planta , Microbiologia do Solo , Solo/química , Artemisia , Bactérias , Biomassa , Carbono/análise , Celulose/análise , China , Ecossistema , Fungos , Nitrogênio/análise , Poaceae , Thymus (Planta)RESUMO
In order to research into the influence of Grain to Green Project in Ziwuling forest region, this paper took three typical plantations which were Robinia pseudoacacia plantation, Pinus tabuliformis plantation, and Platycladus orientalis plantation in the Ziwuling forest region of Shaanxi Province as research objects and analyzed the carbon, nitrogen and phosphorus contents of leaf, litter and soil among the three plantations. The results showed that the contents of C, N and P in the three plantations were in order of leaf > litter > soil, the contents of N and P in leaf of R. pseu-doacacia plantation were significantly higher than that of P. tabuliformis plantation and P. orientalis. Leaf N:P was 12.21, 5.36 and 6.09 in R. pseudoacacia plantation, P. tabuliformis plantation and P. orientalis plantation, respectively. It was indicated that the three species were all subject to N deficiency. C:N and C:P showed the trend of litter > leaf > soil, and N:P demonstrated the trend of leaf > litter > soil. There were highly significant positive relationships in C:N between leaf and litter in P. tabuliformis plantation. N and P in the leaf development process of R. pseu-doacacia plantation were proportionally absorbed, and proportionally remained in the litter after N and P resorption. R. pseudoacacia was the better plantation species than P. tabuliformis and P. orientalis in the south fo-rest zone on the Loess Plateau.
Assuntos
Florestas , Folhas de Planta/química , Solo/química , Carbono/análise , China , Cupressaceae , Nitrogênio/análise , Fósforo/análise , Pinus , RobiniaRESUMO
In order to explore the distribution characteristics of organic carbon of different forms and the active enzymes in soil aggregates with different particle sizes, soil samples were chosen from forest zone, forest-grass zone and grass zone in the Yanhe watershed of Loess Plateau to study the content of organic carbon, easily oxidized carbon, and humus carbon, and the activities of cellulase, ß-D-glucosidase, sucrose, urease and peroxidase, as well as the relations between the soil aggregates carbon and its components with the active soil enzymes were also analyzed. It was showed that the content of organic carbon and its components were in order of forest zone > grass zone > forest-grass zone, and the contents of three forms of organic carbon were the highest in the diameter group of 0.25-2 mm. The content of organic carbon and its components, as well as the activities of soil enzymes were higher in the soil layer of 0-10 cm than those in the 10-20 cm soil layer of different vegetation zones. The activities of cellulase, ß-D-glucosidase, sucrose and urease were in order of forest zone > grass zone > forest-grass zone. The peroxidase activity was in order of forest zone > forest-grass zone > grass zone. The activities of various soil enzymes increased with the decreasing soil particle diameter in the three vegetation zones. The activities of cellulose, peroxidase, sucrose and urease had significant positive correlations with the contents of various forms of organic carbon in the soil aggregates.
Assuntos
Carbono/química , Enzimas/metabolismo , Florestas , Pradaria , Solo/química , Celulase/metabolismo , Tamanho da Partícula , Peroxidases/metabolismo , Urease/metabolismo , beta-Glucosidase/metabolismoRESUMO
The purpose was to characterize the effects of vegetation types on plant leaf and litter carbon (C), nitrogen (N), phosphorus (P), potassium (K) and C: N: P: K ecological stoichiometric characteristics in seven dominant plant species, including Robinia pseudoacacia, Syringa, Sophora viciifolia, Hippophae rhamnoides, Rosa xanthina, Artemisia sacrorum, Artemisia giraldii, of Zhifanggou Watershed on the Loess Plateau, China. This paper indicated the differences between the contents of C, N, P and K and the characteristics of ecological stoichiometric in the different vegetation types, including forest type, shrub type and grass type. Concentrations of C, N, P and K were measured, and C: N: P: K was estimated for different vegetation types. There were no significant differences in leaf C, N and P concentrations among the three vegetation types. But significant differences in leaf K concentration existed, and the K concentration in leaf was the highest in grass type, and the lowest in shrub type. The contents of C, N, P and K in leaf were much higher than those in litter, especially in shrub and grass types. The resorption efficiencies of C, N, P and K were different, and their ranges varied 6.16%-22.84%, 24.38%-65.18%, 22.38%-77.16% and 60.99%- 89.35%, respectively. Grass type had the highest C, P and K resorption efficiencies, and the lowest N resorption efficiency. Values of the N: P ratio in leaf varied in the range of 12.14-19.17, and varied in the range of 12.84-30.67 in litter. Values of the N: P ratio in leaf were the highest in shrub type (19. 17), and the lowest in grass (12. 14), indicating that the growth of shrub plants was limited by P, while the growth of grass plants was limited by N. The K concentration in leaf was significantly negatively correlated with values of the N: P ratio in leaf, and the K concentration in litter was significantly negatively correlated with values of the C: P ratio in leaf. Findings in this study highlighted the characteristics of accumulation and and return of leaf and litters nutrients during the different vegetation succession on the Loess Plateau.
Assuntos
Ecossistema , Folhas de Planta/química , Carbono , China , Nitrogênio , Fósforo , Poaceae , Potássio , ÁrvoresRESUMO
Soil samples from different aspects (southern slope and northern slope) under the same vegetation in two typical vegetation zones (forest vegetation zone and steppe vegetation zone) of Yanhe basin in the loess hilly area were chosen and analyzed, in order to investigate the content and correlation of soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN), soil microbial biomass phosphorus (SMBP) and dissolved organic carbon (DOC). The results show that, in 0-10 cm soil layer of forest vegetation zone, SMBC in southern slope and northern slope are 532.1-792.5 mg x kg(-1) and 333.6-469.8 mg x kg(-1), SMBN are 53.66-87.31 mg x kg(-1) and 47.58-61.38 mg x kg(-1) respectively, both of them are higher in southern slope than those in northern slope, but in steppe vegetation zone, SMBC and SMBN in southern slope are lower than those in northern slope, with SMBC of southern slope and northern slope are 68.90-75.34 mg x kg(-1) and 65.29-128.67 mg x kg(-1), SMBN are 13.94-18.61 mg x kg(-1) and 13.00-20.10 mg x kg(-1) respectively, SMBP in both vegetation zones have a different variation trend compared with SMBC and SMBN; the ratio of SMBC to the sum of SMBC plus DOC (SMBC + DOC) in southern slope of forest vegetation zone reaches the maximum value in two vegetation zones, which is 77.74%. In steppe vegetation zone, this ratio both decreases from northern slope to southern slope and 0-10 cm soil layer to 10-30 cm soil layer. The difference of soil moisture and temperature between different aspects under the same vegetation have a significant effect on soil microbial biomass, it also makes the ratio of SMBC to SMBC + DOC different, SMBC + DOC can reflect soil carbon availability better than SMBC, there might be an obvious change in soil microbial communities in 0-10 cm soil layer of different aspects in forest vegetation zone.
Assuntos
Biomassa , Carbono/química , Microbiologia do Solo , Solo/química , Nitrogênio/química , Fósforo/químicaRESUMO
Taking the rhizosphere and non-rhizosphere soils of five typical plants Agropyron cristatum, Artemisia frigida, Pseudoraphis bungeana, Thymus mongolicus, and Artemisia sacrorum in a mountainous area of southern Ningxia as test objects, this paper studied their C and N forms contents. The C and N forms contents in the rhizosphere and non-rhizosphere soils differed with plant species. In the rhizosphere soil of A. sacrorum, the C content was the highest, with the total soil organic C (TOC), light fraction organic C (LFOC), and heavy fraction organic C contents being 22.94, 1.95, and 20. 88 g kg-1, respectively. In the rhizosphere soil of P. bungeana, the N content was the highest, with the total N (TN), mineralizable N (MN), and available N contents being 2.05 g kg-1 , 23.73 mg kg-1, and 11.99 mg kg-1 , respectively. In the rhizosphere soil of A. frigida, the LFOC/TOC and MN/TN ratios were the highest, which benefited the C and N transformed into more active forms. Light fraction organic C and mineralizable N could be used as the sensitive indicators of plant habitat change. For the five plant species, the contents of different C and N forms in the rhizosphere soil were generally higher than those in the non-rhizosphere soil.
Assuntos
Carbono/química , Nitrogênio/química , Raízes de Plantas/metabolismo , Plantas/metabolismo , Rizosfera , Agropyron/metabolismo , Altitude , Artemisia/metabolismo , China , Ecossistema , Thymus (Planta)/metabolismoRESUMO
A novel actinobacterium, designated strain F22(T), was isolated from grassland soil collected from the Ziwuling area on the Loess Plateau, China. The novel strain was found to have morphological and chemotaxonomic characteristics typical of members of the genus Streptomyces. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain F22(T) belonged to the genus Streptomyces, being most closely related to Streptomyces resistomycificus NBRC 12814(T) (98.28â% sequence similarity), Streptomyces ciscaucasicus NBRC 12872(T) (98.14â%), Streptomyces chartreusis NBRC 12753(T) (98.14â%) and Streptomyces canus NRRL B-1989(T) (98.14â%). In DNA-DNA hybridizations and comparisons of morphological and phenotypic data, strain F22(T) could be distinguished from all of its closest phylogenetic relatives. Strain F22(T) exhibited antibacterial and antifungal activity, especially against Staphylococcus aureus, Bacillus subtilis and Cylindrocarpon destructans. Based on the DNA-DNA hybridization data and morphological, phenotypic and phylogenetic evidence, strain F22(T) represents a novel species of the genus Streptomyces, for which the name Streptomyces ziwulingensis sp. nov. is proposed. The type strain is F22(T) (â=âCCNWFX 0001(T)â=âJCM 18081(T)â=âACCC41875(T)).
Assuntos
Filogenia , Microbiologia do Solo , Streptomyces/classificação , Técnicas de Tipagem Bacteriana , Composição de Bases , China , DNA Bacteriano/genética , Ácidos Graxos/análise , Dados de Sequência Molecular , Hibridização de Ácido Nucleico , Poaceae , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Streptomyces/genética , Streptomyces/isolamento & purificação , Vitamina K 2/análiseRESUMO
Soil fertility is important factors for growth and productivity of vegetation. The relationship between vegetation and soil fertility deserves attention due to its scientific importance and practical applications. However, the effects of soil fertility on vegetation development and succession are poorly documented. Here we study soil fertility in Yanhe watershed at northern Shaanxi on five different land uses, namely shrubland, farmland, natural grassland, woodland, and artificial grassland, and in soil under restoration for 5, 10, 15, 20, and 25. Attribute recognition model based on entropy weight was used to evaluate the soil fertility of typical region in the Loess Plateau of China, which contained 52 soil samples with 6 physical and chemical indexes, including soil organic matter, soil total nitrogen, total phosphorus, etc. The results show that (1) Land use has an obvious effect on soil bulk density, total porosity and capillary porosity of surface layers, but not significant in the subsurface layer; (2) SOM, Ntotal, Nhydro and Kavail are the most in shrubland and woodland while Ptotal and Pavail in farmland, respectively; (3) Vegetation succession on eroded soil result in significant changing of soil fertility; and (4) Vegetation succession on eroded soil result in significant changing of soil fertility.
RESUMO
The relationship between vegetation and soil moisture deserves attention due to its scientific importance and practical applications. However, the effects of soil moisture on vegetation development and succession are poorly documented. Here we study soil water storage in Yanhe watershed at northern Shaanxi on five different land uses, namely shrubland, farmland, natural grassland, woodland, and artificial grassland, and in soil under restoration for 5, 10, 15, 20 and 25. The results show that (1) soil water in soil 0-60 cm below ground is the highest in farmland, and lower in shrubland, artificial grassland, natural grassland and woodland; (2) soil water in artificial grassland and woodland decreases rapidly as the soil depth increases; whereas soil water in farmland, natural grassland, shrubland and woodland decreases; (3) soil water storage of farmland is greater than that of shrubland, artificial grassland, natural grassland and woodland; and (4) the vegetation succession in soil undergo restoration for different years on eroded soil results in a decrease in soil water storage.