Soil science
Yahya Kooch; Mahmood Tavakoli Feizabadi; Katayoun Haghverdi
Abstract
IntroductionSoil, as habitat substrate, helps to regulate important ecosystem processes, including nutrient absorption, organic matter decomposition. Water availability and the well-being of humanity are directly linked to soil functions. On the other hand, vegetation with different species and ages ...
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IntroductionSoil, as habitat substrate, helps to regulate important ecosystem processes, including nutrient absorption, organic matter decomposition. Water availability and the well-being of humanity are directly linked to soil functions. On the other hand, vegetation with different species and ages have significant effects on the status of the surface soil layer through the creation of diverse environmental conditions and the production of different organic substances. However, few studies have been conducted in relation to the effect of the age of afforestation and the type of vegetation on the soil status. Considering that a practical, complete and effective assessment of soil condition should be the result of simultaneous measurement of physical, chemical and biological indicators, hereupon, the present study aimed to investigate the effect of 20-year old poplar stand, 20-year old maple stand, 10-year old poplar stand, 10-year old maple stand and rangeland cover, in plot 3 of Delak-Khil series of wood and paper forests in Mazandaran province, on the organic layer properties and physical, chemical and biological (including microbial activities, enzyme activity, earthworm population and biomass, the number of soil nematodes and root biomass) properties of the surface soil layer. Materials and MethodsFor this purpose, some parts of the study area were selected which are continuous with each other and have minimum height difference from the sea level, minimum change in percentage and direction of slope. Then, in order to take samples from the organic and surface layer of the soil, three one-hectare plots with distances of at least 600 meters were selected in each study habitats. From each of the one-hectare plots, 5 leaf litter samples and 5 soil samples (30 cm × 30 cm by 10 cm depth) were taken to the laboratory for analysis . In total, 15 litter samples and 15 soil samples were collected from each of the habitats under study. One part of the soil samples was passed through a 2 mm sieve after air-drying to perform physical and chemical tests, and the second part of the samples was kept at 4 °C for biological tests. One-way analysis of variance tests was used to compare the characteristics of organic layer and soil between the studied habitats. In the following, Duncan's test (P>0.05) was used to compare the average parameters that had significant differences among different habitats.Results and DiscussionThe results of this research showed that afforested stands with different ages and pasture cover had a significant effect on the characteristics of the organic and surface soil layers. The results indicated the improvement of most of the characteristics of the organic and surface soil layer in the afforested stands, especially the 20-year old afforestation compared to the rangeland cover. The organic matter produced in 20-year old afforestation, especially with poplar species, had a higher quality (high nitrogen and carbon content and low carbon-to-nitrogen ratio) compared to organic matter produced in 10-year old afforestation and pasture cover. Most of the physicochemical characteristics of the soil under 20-year old afforestation were in a better condition than the other studied habitats. Also, according to the results of this research, the highest values of biological characteristics such as microbial activity, enzyme activity, and the population of earthworms and nematodes were observed in the subsoil of 20-year old afforestation especially with poplar species. Based on the results obtained from the principal component analysis, the higher values of nitrogen, phosphorus, calcium, magnesium and potassium content of the organic layer led to the improvement of soil fertility characteristics, microbial activities, enzyme activity, earthworm population, the number of soil nematodes and root biomass, respectively, under poplar and maple plantation for 20 years, meanwhile, 10-year old plantation, especially with maple species, and rangeland with the production of organic materials with high carbon content and carbon to nitrogen ratio, resulted in the reduction of organic matter decomposition (greater thickness of organic layer), and consequently the reduction of the mentioned properties of the surface soil layer. ConclusionAccording to the findings of this research, it can be concluded that plantation with poplar species, especially after 20 years, had a higher ability to improve the soil condition compared to maple, which can be considered by managers in future afforestation. Also, with the passage of time, the presence of tree covers (poplar and maple) had a higher priority than rangeland cover in improving the fertility status and suitable edaphological conditions of the soil.
Soil science
Y. Kooch; A. Shahpiri; K. Haghverdi
Abstract
Introduction
Forests, encompassing approximately 30% of the Earth's land area, hold significant ecological importance due to their rich biodiversity and the multitude of environmental services they provide. These ecosystems outperform other terrestrial habitats, making them invaluable to all life forms ...
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Introduction
Forests, encompassing approximately 30% of the Earth's land area, hold significant ecological importance due to their rich biodiversity and the multitude of environmental services they provide. These ecosystems outperform other terrestrial habitats, making them invaluable to all life forms on our planet. The destruction of forest habitats and changes in land use patterns exert significant impacts on the variability of soil quality indicators. The consequence of forest degradation encompass various adverse consequences, including the destruction of wildlife habitats, climate change, global warming, diminishing plant and animal biodiversity, and reduced water conservation capacity. Extensive research has been conducted to investigate soil quality in diverse land uses within temperate regions. However, there is a noticeable scarcity of studies focusing on semi-arid regions. It is imperative to note that a comprehensive and practical assessment of soil condition necessitates the simultaneous measurement of physical, chemical, and biological indicators. Such an integrated approach ensures a thorough and effective evaluation of soil quality. The primary objective of this study was to assess the impact of various land uses, namely natural forest (C. betulus - P. persica), plantation (Q. castaneifolia), garden, rangeland, and agricultural lands (rice), on the physical, chemical, and biological properties of the organic and mineral soil layers. Specifically, the investigation focused on the evaluation of fauna and flora, microbial communities, and enzyme activities. The study was conducted in the semi-arid region of Kajur Nowshahrmourd.
Materials and Methods
To achieve this objective, contiguous sections of the study area were carefully chosen, ensuring minimal variations in height above sea level, percentage and direction of slope. Subsequently, three slice of one-hectare dimension plots (100 × 100) were selected within each study habitat, with a minimum distance of 600 meters between them. From each one-hectare plot, four leaf litter samples and four soil samples (30 cm × 30 cm, 10 cm depth) were collected and transported to the laboratory for analysis. In total, 12 litter samples and 12 soil samples were collected from each of the habitats. The soil samples were divided into two parts: one part was air-dried and then passed through a 2 mm sieve for subsequent physical and chemical testing, while the other part was stored at 4 degrees Celsius for biological assessments. One-way analysis of variance tests were employed to compare the characteristics of the organic layer and soil among the studied habitats. Furthermore, Duncan's test (P>0.05) was utilized to compare the average parameters that exhibited significant differences among the different habitats.
Results and Discussion
The findings derived from this investigation underscore the substantial variability in organic layer characteristics across different vegetation types. Natural forests emerged as the most prominent in terms of thickness, nitrogen content, and calcium concentration, whereas agricultural areas exhibited the lowest values. Grassland areas displayed the highest carbon content and carbon-to-nitrogen ratio, while agricultural and natural forest areas demonstrated comparatively lower values. Agricultural lands demonstrated elevated bulk density and sand content, whereas natural forests exhibited the lowest values. Notably, natural forests showcased the highest porosity, aggregate stability, silt percentage, and macro- and micro-aggregate quantities, while agricultural areas presented the lowest values. Chemical analysis of the soil indicated that natural forests recorded the highest values for most chemical characteristics, while agricultural lands displayed the lowest values. Biological attributes generally exhibited the highest levels in natural forests and the lowest levels in agricultural areas. Specifically, the abundance and biomass of epigeic and endogeic fauna did not exhibit significant differences among different land uses during the summer season. Managed forests demonstrated the highest values for moisture content, basal respiration, substrate-induced respiration, and microbial biomass carbon. Conversely, agriculture exhibited the lowest values in these regards. The microbial biomass carbon-to-nitrogen ratio was highest in agricultural areas, while natural forests displayed the lowest value. Natural forests displayed the highest values for most nitrogen transformation characteristics, whereas agricultural areas exhibited the lowest values. Nitrogen nitrification and mineralization showed a decreasing trend across different land uses during the summer and autumn seasons. The type of vegetation cover also significantly influenced the variability of soil ammonium and nitrate levels.
Conclusion
Based on the results obtained from this study, it can be inferred that the preservation and conservation of natural forest cover should be given utmost importance. Additionally, in degraded areas, the establishment of woody vegetation can serve as a viable approach for the restoration of ecosystems with similar ecological conditions. Furthermore, the presence of tree covers, specifically C. betulus and P. persica, is of greater significance compared to rangeland and agricultural land uses in enhancing soil fertility and creating favorable biological conditions. As a result, this research provides valuable insights into the impact of different land uses on the characteristics of the organic and mineral soil layers in mountainous habitats. The information obtained can be instrumental in guiding natural resource managers and offering practical assistance in decision-making processes.
