scholarly journals Do Fire Regime Attributes Affect Soil Biochemical Properties in the Same Way under Different Environmental Conditions?

Forests ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 274 ◽  
Author(s):  
Víctor Fernández-García ◽  
Elena Marcos ◽  
Otilia Reyes ◽  
Leonor Calvo

Global change is altering fire frequency and severity in many regions across the world. In this work, we studied the impact of different frequency and severity regimes on the soil biochemical properties in burned areas with different environmental conditions. We selected three sites dominated by pine ecosystems along a Mediterranean-Transition-Oceanic climatic gradient, where we determined the fire frequency, and severity of the last wildfire. Four years after the last wildfire, we established 184 4 m2 plots. In each plot, we collected a composed soil sample from a 3 cm depth, and measured several ecological variables potentially affected by the fire frequency and severity (cover of bare soil, cover of fine and coarse plant debris, cover of vegetation, and vegetation height). From each soil sample, we analyzed the enzymatic activities corresponding to the biogeochemical cycles of carbon, nitrogen, and phosphorus (β-glucosidase, urease, and acid-phosphatase, respectively), and the microbial biomass carbon. The results indicated that fire frequency only played a significant role in soil biochemical properties at the Mediterranean and Transition sites. Specifically, we found that increases in frequency contributed to increased urease and phosphatase activities (at the Transition site), as well as microbial biomass carbon (at the Mediterranean and Transition sites). In relation to burn severity, we found opposite patterns when comparing the Mediterranean and Oceanic sites. Specifically, increased severity significantly decreased β-glucosidase, urease, and microbial biomass carbon at the Mediterranean site, whereas at the Oceanic one, severity significantly increased them. Burn severity also decreased microbial biomass carbon at the Transition site. Our results also indicated that, overall, fire frequency determined the studied ecological variables at the Mediterranean and Transition sites, but clear indirect effects on biochemical properties due to changes in ecological variables were not found. This study adds to the knowledge on the impact of shifts in fire regimes on soils in the current context of change.

1988 ◽  
Vol 68 (3) ◽  
pp. 463-473 ◽  
Author(s):  
V. V. S. R. GUPTA ◽  
J. R. LAWRENCE ◽  
J. J. GERMIDA

This study investigated the impact of repeated application of S° fertilizer on microbial and biochemical characteristics of two Grey Luvisolic soils. The Waitville pasture plots received Agri-Sul at a rate of 22 or 44 kg S° ha−1 yr−1 for 5 yr, whereas the Loon River canola-summerfallow plots received single or double applications of Flow-able Sulfur (50 kg S° ha−1) or Agri-Sul (100 kg S° ha−1). Application of S° fertilizer significantly decreased the pH in both soils. Organic C declined in S°-treated plots of the Waitville soil, and there was a narrowing of C:N:S ratios in both soils. Application of S° fertilizer significantly increased the total S, HI-S and sulfate sulfur levels of both soils. There was a 29–45% and 2–51% decline in microbial biomass carbon content due to S° fertilizer application in Waitville and Loon River soils, respectively. Repeated application of S° also resulted in a decline in respiration, dehydrogenase, urease, alkaline phosphatase and arylsulfatase activities, along with populations of protozoa, algae and nitrifiers in both soils. Significant correlations observed among related characteristics further emphasized the treatment effects. These results indicate that the impact of repeated application of S° fertilizer on microbial biomass and activity should be considered when recommending S° as a fertilizer for sulfur-deficient soils. Key words: Sulfur (elemental), microbial biomass, dehydrogenase, urea, phosphomonoesterases, arylsulfatase


Author(s):  
T. L. Ataikiru ◽  
G. S. C. Okpokwasili ◽  
P. O. Okerentugba

This study aimed at determining the impact of Carbofuran and Paraquat use on soil microbial biomass and microbial population as soil health index. Pot experiment, set-up as a randomized block design with replicates was done, with both pesticides applied at recommended rates for eight weeks. Twenty-four (24) soil samples were taken from the pesticides polluted soil as well as the unpolluted soil. These samples were used to assess the effect of pesticides on microbial biomass carbon (MB-C), nitrogen (MB-N) and phosphorus (MB-P). Also, microbial population (determined by aerobic spread plate count) of the pesticide-polluted soils was used as health index. The assessments were done weekly. The microbial biomass values increased from 273.48 µg/g to 293.15 µg/g (MB-C), 17.275 µg/g to 18.52 µg/g (MB-N) and 10.605 µg/g to 11.37 µg/g (MB-P) in carbofuran treated soil while increases from 277.26 µg/g to 288.365 µg/g (MB-C), 17.515 µg/g to 18.22 µg/g (MB-N) and 10.745 µg/g to 11.18 µg/g (MB-P) were observed in paraquat treated soil. The microbial counts in treated soils were within the ranges of 1.95 x 106 cfu/g to 1.03 x 107 cfu/g, 8.83 x 104 to 1.90 x 105 cfu/g, 1.08x 104 to 2.43 x 104, 1.15 x105 to 2.17 x 105 cfu/g, 1.38 x 105 to 2.22 x 105 cfu/g for total heterotrophic bacterial, fungal, actinomycetes, phosphate solubilizers, nitrifiers counts, respectively. The pesticides had no negative effects on the MB-C, MB-N, MB-P and soil microorganisms at recommended field rates, hence their use must be strictly based on these rates. These findings indicate that the relationship between soil nutrients and microbial biomass is significant in facilitating the use of microbial biomass as an important soil quality indicator.


2021 ◽  
Vol 25 (11) ◽  
pp. 34-37
Author(s):  
Anis Naushi ◽  
Ajay Kumar Arya

This investigation was aimed toward assessing the impact of heavy metals on soil microbial cycles. The impacts of lead (Pb) and cadmium (Cd) at various concentrations were researched over a time of about two months. Chloride salts of Pb and Cd were added independently and in blend to soil samples at room temperature (27ºC) in various polythene packs. Samples were taken from the sacks at about fourteen days span and estimations were taken of the microbial biomass carbon (MBC). The outcomes showed that there was a significant reduction in the microbial biomass carbon for all treated soils from the second week to the 6th week. However, on 8th week, increase in microbial biomass carbon was observed. At the 6th week, 2000mgkg-1Pb and 40mgkg-1Cd gave the main reduction (P < 0.05) in microbial biomass carbon of 98%. A critical decrease in biomass carbon in metal contaminated soil demonstrated that this parameter is a decent marker of toxicity of metals on soil microflora.


2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Devanshi Singh ◽  
Priyanka Sharma ◽  
Ujjwal Kumar ◽  
Achlesh Daverey ◽  
Kusum Arunachalam

Abstract Background Forest fire incidences in the Himalayan region of Uttarakhand, India are very common in summers. Pine and oak are the principal and dominant species of Himalayan subtropical forest and Himalayan temperate forest, respectively. Forest vegetation influences the physicochemical and biological properties of soil and forest fire in pine and oak forests may have a different effect on the physicochemical and biological properties of soil. Therefore, the present study was carried out to assess the impact of forest fire on soil microbial properties, enzymatic activity, and their relationship with soil physicochemical properties in the advent of forest fire in the pine and oak forests of the Garhwal region of Uttarakhand Himalaya, India. Results The soil microbial biomass carbon and nitrogen, soil basal respiration, and acid phosphatase activity decreased, whereas dehydrogenase activity increased at burnt sites of both forest types. The overall change in soil microbial biomass carbon was 63 and 40% at the burnt oak forest and burnt pine forest, respectively. Dehydrogenase activity and acid phosphatase activity showed a strong positive correlation with soil organic matter (r = 0.8) and microbial indices, respectively. The ratio of soil microbial biomass carbon/nitrogen was reduced at burnt sites of both forest types. Factor analysis results showed that fire had a significant impact on soil characteristics. The soil basal respiration was linked with macro- and micronutrients at burnt sites, whereas at control sites, it was linked with physicochemical properties of soil along with nutrients. Conclusion Forest fire had a significant impact on soil properties of both forest types. The impact of forest fire on soil microbial biomass carbon was stronger in the oak forest than in the pine forest. Forest type influenced soil enzymatic activity at burnt sites. The bacterial community was dominated over fungi in burnt sites of both forests. Soil microbial indices can be used as a selective measure to assess the impact of fire. Furthermore, forest type plays an important role in regulating the impact of forest fire on soil properties.


Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 684
Author(s):  
Mengke Cai ◽  
Shiping Xing ◽  
Xiaoqing Cheng ◽  
Li Liu ◽  
Xinhao Peng ◽  
...  

The stoichiometric ratios of elements in microorganisms play an important role in biogeochemical cycling and evaluating the nutritional limits of microbial growth, but the effects of thinning treatment on the stoichiometric ratio of carbon, nitrogen, and phosphorus in microorganisms remain unclear. We conducted research in a Larix principis-rupprechtti Mayr. plantation to determine the main factors driving microbial carbon (C): nitrogen (N): phosphorus (P) stoichiometry following thinning and the underlying mechanisms of these effects. The plantation study varied in thinning intensity from 0% tree removal (control), 15% tree reduction (high density plantation, HDP), 35% tree reduction (medium density plantation, MDP), and 50% tree reduction (low density plantation, LDP). Our results indicated that medium density plantation significantly increased litter layer biomass, soil temperature, and other soil properties (e.g., soil moisture and nutrient contents). Understory vegetation diversity (i.e., shrub layer and herb layer) was highest in the medium density plantation. Meanwhile, thinning had a great influence on the biomass of microbial communities. For example, the concentration of phospholipid fatty acids (PLFA) for bacteria and fungi in the medium density plantation (MDP) was significantly higher than in other thinning treatments. Combining Pearson correlation analysis, regression modeling, and stepwise regression demonstrated that the alteration of the microbial biomass carbon: nitrogen was primarily related to gram-positive bacteria, gram-negative bacteria, soil temperature, and soil available phosphorus. Variation in bacteria, actinomycetes, gram-positive bacteria, gram–negative bacteria, and soil total phosphorus was primarily associated with shifts in microbial biomass carbon: phosphorus. Moreover, changes in microbial biomass nitrogen: phosphorus were regulated by actinomycetes, gram-negative bacteria, and soil temperature. In conclusion, our research indicates that the stoichiometric ratios of elements in microorganisms could be influenced by thinning management, and emphasizes the importance of soil factors and microbial communities in driving soil microbial stoichiometry.


Forests ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 508 ◽  
Author(s):  
Zhiwei Ge ◽  
Shuiyuan Fang ◽  
Han Chen ◽  
Rongwei Zhu ◽  
Sili Peng ◽  
...  

Soil resident water-stable macroaggregates (diameter (Ø) > 0.25 mm) play a critical role in organic carbon conservation and fertility. However, limited studies have investigated the direct effects of stand development on soil aggregation and its associated mechanisms. Here, we examined the dynamics of soil organic carbon, water-stable macroaggregates, litterfall production, fine-root (Ø < 1 mm) biomass, and soil microbial biomass carbon with stand development in poplar plantations (Populus deltoides L. ‘35’) in Eastern Coastal China, using an age sequence (i.e., five, nine, and 16 years since plantation establishment). We found that the quantity of water-stable macroaggregates and organic carbon content in topsoil (0–10 cm depth) increased significantly with stand age. With increasing stand age, annual aboveground litterfall production did not differ, while fine-root biomass sampled in June, August, and October increased. Further, microbial biomass carbon in the soil increased in June but decreased when sampled in October. Ridge regression analysis revealed that the weighted percentage of small (0.25 mm ≤ Ø < 2 mm) increased with soil microbial biomass carbon, while that of large aggregates (Ø ≥ 2 mm) increased with fine-root biomass as well as microbial biomass carbon. Our results reveal that soil microbial biomass carbon plays a critical role in the formation of both small and large aggregates, while fine roots enhance the formation of large aggregates.


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