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Effect of vegetation type and season on microbial biomass carbon in Central Himalayan forest soils, India
... Each habitat type harbors distinctive ecological characteristics and species compositions that influence regeneration processes and overall forest dynamics (Gairola et al. 2008). These forests face numerous threats, including overexploitation, habitat fragmentation, climate change, and invasion by exotic species (Bargali et al. 2018). ...
... Second, the high seedling-to-tree ratios for invasive species like A. dealbata across all habitats raise substantial conservation concerns. This species is known for its aggressive colonization and potential to alter ecosystem processes (Bargali et al. 2018). The successful establishment of this invasive, even in relatively intact forest habitats, suggests underlying disturbance factors or changing environmental conditions that may favor non-native species over native forest components. ...
... This species showed new regeneration in Oak and Oak-Pine habitats and good regeneration in Pine habitat, suggesting it may become increasingly prevalent in the future forest composition. These invasive dynamics align with global patterns of increasing biotic homogenization in forest ecosystems due to human-mediated species introductions and disturbances (Bargali et al. 2018). ...
The phytosociological data were collected and analyzed to understand tree species composition, diversity, and regeneration patterns across three distinct forest habitats (Oak, Pine, and Oak-Pine mixed) in the Ranikhet forest of Almora District, Kumaon Himalaya, Uttarakhand, India. The study was conducted from 2021 to 2022. A total of 120 plots with a radius of 10 m were established using a stratified random technique to sample tree data. Regeneration (seedlings and saplings) was quantified in 3 m radius concentric circular plots within the existing 10 m tree plots. Results reveal considerable differences in species composition and regeneration patterns across habitats. The Oak-Pine mixed habitat exhibited the highest species richness (15 species) and diversity (Shannon index: 1.625). In contrast, the Pine habitat showed the lowest diversity (Shannon index: 0.1526) with high dominance of Pinus roxburghii (IVI: 280.89). Tree density varied noticeably across habitats, with the highest in Oak-Pine forest (467.09 individuals/ha), followed by Pine (357.99 individuals/ha) and Oak (291.17 individuals/ ha) habitats. Regeneration analysis indicated that invasive species like Acacia dealbata are successfully established across all habitats, while native species showed variable regeneration patterns. The Oak habitat demonstrated good overall regeneration (seedling density: 3740.77 individuals/ha), whereas Pine and Oak-Pine habitats showed fair regeneration. The high seedling-to-tree ratios for invasive species and the absence of regeneration for several native species raise significant conservation concerns. Quercus leucotrichophora showed fair regeneration in Oak and Oak-Pine habitats but good regeneration in Pine habitat, suggesting potential for oak expansion under favourable conditions. Similarity analysis revealed moderate habitat overlap (Simpson's similarity index: 45.45-61.53%), suggesting distinct ecological niches with the highest similarity between Oak and Pine habitats (61.53%). The findings highlight concerns about the expansion of invasive species and regeneration challenges for some native species, providing valuable insights for sustainable forest management and conservation strategies in the Western Himalayan region. The habitat-specific differences in diversity indices and regeneration patterns underscore the importance of maintaining habitat heterogeneity at the landscape scale for preserving the region's forest biodiversity.
... Changes in vegetation type brought on by human intervention are among the most important variables managing nutrient concentrations in terrestrial ecosystems (Zheng et al. 2019). The vegetation of any ecosystem influences the physico-chemical properties of soil by changing the structure of soil, improving water retention capacity, aeration, infiltration and hydraulic conductivity (Horkar and Totey 2002;Bargali et al. 2018). In the Himalaya, grasslands are crucial for preventing soil erosion and stabilizing the slopes of the hills. ...
... Oak forests are essential to the hill people's subsistence agricultural economy by providing agricultural tools, firewood, and fodder (Singh, Rawat, and Chaturvedi 1984;Bargali et al. 2015). The area covered by oak forests has decreased due to human settlement concentration, (Bargali et al. 2018). Pine, distributed between 1000 and 2000 m elevations is an early successional species which form thin canopy forests with scattered trees. ...
... The parent material and soil weathering together control the soil texture, which has a significant impact on the concentrations and stoichiometry of soil nutrients (Yu et al. 2018;Ge et al. 2019). Due to variations in soil parent substances and rates of soil weathering, soil texture is prone to vary at landscape and regional levels, resulting in a complex interplay between soil texture and the biogeochemical cycles of C, N, and P in soils (Silver et al. 2000;Bargali et al. 2018 ...
Land‐use changes are anticipated to be a substantial contributor to global change climate, substantially causing significant modifications in soil characteristics. This study addressed the impact of land‐use change from native forests to grasslands on the soil physico‐chemical properties in entirely replicated grasslands of three different forest zones (Oak, Pine and Cypress) in temperate region of Kumaun Himalaya. A total of 162 soil samples (6 sites × 3 plots × 3 seasons × 3 depths = 162 samples) were randomly collected from each site in triplicates from depths. The soil texture, bulk density (bD), porosity, water holding capacity, soil moisture content, pH, organic carbon (SOC), total nitrogen (TN), available phosphorus (P) and available potassium (K) were determined at different depths in forest and grassland sites. Results showed that soil bD, pH, SOC, TN, P and K significantly ( p < 0.05) decreased with increasing depth. Moreover, conversion of forests into grassland reduced nutrient concentrations, physical qualities (bD and porosity), and pH levels. The decreasing trend of nutrient along the soil depth explains that the zone of nutrient accumulation is not well established in these grasslands because of the substantial leaching effect. Our findings indicate that conversion of natural forests into grasslands resulted in significant losses of SOC and TN stocks which can be attributed to the disturbance of natural forests. Therefore, while making land‐use change plans, the impact of these alterations on soil nutrients must be considered. These findings emphasize the value of establishing natural vegetation (forests) in these areas to retain nutrients and safeguard soil against runoff and erosion. However, anticipating the physico‐chemical impacts of land‐use alteration necessitates a better comprehension of its relations with other drivers of global change, such as changing climate and nitrogen deposition.
... Moreover, it is essential to take into account the significant differences in physico-biochemical properties among the sampling sites. These properties typically exhibit spatial and temporal variations influenced by factors such as topography, climate, weathering processes, and vegetation cover (Bargali et al., 2018). Although there were no significant increases in microbial C or N biomass observed at our site, the noteworthy microbial 15 N immobilization we detected indicates that microbial metabolic activity remains substantial during winter. ...
... Secondly, the freeze-thaw cycles may also lead to the mortality of fine roots and microorganisms, causing cell lysis and subsequent mineral N release (Gaul et al., 2008). Furthermore, soil nutrients are significantly influenced by litter inputs (Bargali et al., 2018). The process of snowmelt and soil thawing likely accelerates litter decomposition, impacting soil nutrient dynamics by breaking down organic matter and releasing nutrients into the soil (Lal, 2004;Bargali et al., 2018). ...
... Furthermore, soil nutrients are significantly influenced by litter inputs (Bargali et al., 2018). The process of snowmelt and soil thawing likely accelerates litter decomposition, impacting soil nutrient dynamics by breaking down organic matter and releasing nutrients into the soil (Lal, 2004;Bargali et al., 2018). These processes enhance nutrient availability in early spring, thereby supporting microbial activity. ...
In seasonal snow-covered regions, the soil microbial community remains highly active, enabling nitrogen (N) mineralization processes to occur even during the winter. Therefore, winter N accumulation is likely to be a primary N source for plant growth in the subsequent spring. However, the availability of winter N resources (i.e., ammonium and nitrate N) to soil microorganisms and plants in temperate grasslands remains unclear. Here, we applied 15 NH 4 Cl and K 15 NO 3 tracers before autumn-winter freezing, and then investigated the retention of both 15 N tracers in soil microorganisms and different plants during the winter and spring period in a typical steppe. The results showed that approximately 33 % and 27 % of 15 NH 4 Cl and K 15 NO 3 tracers were immobilized by soil microorganisms, while little had been uptake by plants during winter. In the subsequent spring, soil retained 32 % and 34 %, microorganisms immobilized 5.1 % and 5.2 %, plant acquired 40 % and 28 % of the 15 NH 4 Cl and K 15 NO 3 tracers, respectively. At a temporal scale, perennial bunch grasses first acquired 15 N in the winter-spring transition, followed by perennial rhizome grasses and forbs in early spring, while legumes utilized little 15 N. In contrast, the 15 N absorption capacity of perennial rhizome grasses and perennial forbs was similar to that of bunch grasses. Additionally, only dominant bunch grasses showed a preference for ammonium N over nitrate N, while other plant species did not exhibit a clear preference for different forms of N. Our results suggest that the temporal differentiation of N utilization between plants and microorganisms enhances the availability of winter N sources. Importantly, the differences among plant species in the timing and quantity of winter N resource utilization contribute to species coexistence in temperate grasslands. This study highlights the crucial role of winter N accumulation as a primary N source for plant growth in temperate grasslands. Understanding the availability of winter N sources for plant and microbial growth is essential for predicting plant community dynamics and species coexistence in these ecosystems.
... Any ecosystem's composition and variation is recognized by the species inventory and diversity parameters (K. Bargali et al., 2018). The highest number of species during the rainy season, followed by winter and summer, indicates notable seasonal variation in distribution of species in grasslands of both the forest zones. ...
... These differences occur due to the variation in its geography, topography, vegetation composition, climate, land use pattern, weathering processes and other biotic as well as abiotic properties (K. Bargali et al., 2018). The soil texture is sandy loam for both the grassland. ...
Grasslands in the Kumaun Himalayan region, formed largely due to degradation of forests by
natural and anthropogenic disturbances, are ecologically significant but poorly studied in
terms of dry matter dynamics and net primary productivity. This study compared seasonal
biomass and productivity variations in grasslands under two contrasting forest zones (Banj oak
and Chir pine). Three permanent plots were established in each zone and within each of these
plots 10 quadrats of 1m × 1m were placed randomly on monthly basis. Maximum density, total
basal area, diversity and live aboveground biomass were observed during the rainy season,
while dead shoot biomass peaked in winter. Aboveground net productivity ranged from 280.96
g m-2 to 394.83 g m-2 for oak and pine zone grassland, respectively. All biomass compartments
varied significantly with season, site, and their interaction (p<0.05). High aboveground biomass
and productivity during rainy season indicates that precipitation promotes aboveground
biomass in grasslands. Oak zone grassland showed lower productivity and nutrient content
as compared to pine zone due to greater grazing and human pressure. This study concludes
that grassland productivity was directed aboveground during the monsoon season and belowground during post-monsoon season, with environmental and anthropogenic factors driving
these patterns. Understanding these dynamics is crucial for managing and conserving
Himalayan grassland ecosystems.
... Studies on soil MBC have been carried out by several researchers in different countries around the world (Soleimani et al. 2019;Bargali et al. 2018;Singh and Gupta 2018;Welemariam et al. 2018;Fang et al. 2014). Likewise, different ecological researches in southern Ethiopia under various ecosystems have been conducted. ...
... Low MBC was reported from non-conserved communal grazing lands in northern Ethiopia (Welemariam et al. 2018), indicated a decreased amount of MBC from disturbed environments (Gelaw et al. 2015). Disturbed ecosystems had lower MBC (Soleimani et al. 2019;Van Leeuwen et al. 2017;Bardgett 2005). Erosion caused a more severe disturbance to soil microbial biomass (Xiaojun et al. 2013), which could be responsible for the loss of carbon in the form of carbon dioxide (Gonzalez-Quiñones et al. 2011). ...
The land-use change from agroforestry (AF) to monoculture-based agriculture has the potential to change soil microbial biomass carbon (MBC). The MBC has been used as an indicator of soil quality as well as to determine the microbial status of soil. The aim of this study was to analyze the distribution of soil MBC across different agroforestry practices (AFPs) at two depths in southern Ethiopia. Soil samples were collected from cropland/parkland, woodlots, home gardens, and trees on soil and water conservation-based agroforestry practices (AFPs). The MBC was determined using the difference in fumigated and non-fumigated extracted carbon contents. The MBC and soil microbial biomass quotient (MBQ) were significantly different among the different AFPs (P < 0.05). The highest contents of MBC were reported from homegarden on topsoil (505.36 ± 12.45 mg kg⁻¹) and subsoil (401.88 ± 7.26 mg kg⁻¹) soil depths (topsoil = 0–30 cm, subsoil = 30–60 cm), followed by woodlot (topsoil: 464.37 ± 9.19 mg kg⁻¹) and (subsoil: 380.24 ± 6.88 mg kg⁻¹), while the lowest result was registered from the subsoil of the croplands (153.10 ± 46.44 mg kg⁻¹). The higher percentage of MBQ was recorded under the woodlots in topsoil layers (1.48%) and subsoil (1.37%), followed by homegarden (topsoil = 1.41%, subsoil = 1.25%), while the lowest was found under the cropland in subsoil (0.57%). The highest content of soil organic carbon was found under homegarden in topsoil (3.62%) and subsoil (3.23%) followed by woodlot (topsoil: 3.16%, subsoil: 2.87%) and trees on soil and water conservation structures (topsoil: 2.69%, subsoil: 2.51%), while the lowest value was registered under cropland/parkland AF practices (topsoil: 2.67%, subsoil: 2.46%). The distribution of MBC was significantly related to soil organic carbon, soil total nitrogen, and soil pH in topsoil. Homegarden and woodlot AFPs were suitable for soil MBC improvement among the different AFPs studied, implying that tree-based systems are important for increasing of MBC and ecosystem stability.
... The results of previous studies that investigated the impacts of seasonal drought on soil microbial biomass are controversial [46,47]. Bargali et al. found that soil MBC was higher in winter (relatively drier and colder) than that in the rainy season (relatively wetter and hotter) in three forest types (Banj-oak forest, Chir-pine forest, and mixed oakpine forest) in Central Himalaya in India because dense individual plants grew slowly or stopped growing in winter, resulting in low nutrient demand for plant growth and high nutrient retention in the soil for microbial growth and reproduction [46]. ...
... The results of previous studies that investigated the impacts of seasonal drought on soil microbial biomass are controversial [46,47]. Bargali et al. found that soil MBC was higher in winter (relatively drier and colder) than that in the rainy season (relatively wetter and hotter) in three forest types (Banj-oak forest, Chir-pine forest, and mixed oakpine forest) in Central Himalaya in India because dense individual plants grew slowly or stopped growing in winter, resulting in low nutrient demand for plant growth and high nutrient retention in the soil for microbial growth and reproduction [46]. However, Manral et al. reported that soil microbial biomass was highest in the rainy season and lowest in winter in a temperate mixed oak-pine forest of Central Himalaya in India due to higher immobilization of nutrients from decomposing litter by microbes as the decomposition rate of litter and microbial activity are at their peak during the rainy period [47]. ...
Severe seasonal droughts driven by global climate change significantly alter the cycling of carbon and nutrients in forest ecosystems, while the investigation into the impacts of floor mass and plant roots on soil microbial biomass within the context of recurrent seasonal droughts is still rare. To investigate the environmental determinants governing soil microbial biomass with the escalating severity of seasonal droughts, we conducted a study in a montane subtropical moist evergreen broad-leaved forest in southwestern China from June 2019 to May 2023. The study results revealed that soil microbial biomass, as well as soil moisture, floor mass, and plant roots, showed an apparent single-hump modal within one year. In the comparative analysis of the soil microbial biomass fluctuation amplitudes across control and watered plots, a discernible disparity was observed, indicating significant differences in microbial biomass dynamics between the respective experimental conditions. The pooled data revealed a statistically significant influence of seasonal drought, floor mass, plant roots, and their reciprocal interactions on the soil microbial biomass, highlighting these factors as pivotal determinants of microbial community dynamics. This study elucidates the interactive regulatory mechanisms by which seasonal drought, floor mass, and plant roots collectively modulate soil microbial biomass within tropical and subtropical forests, offering insights into the complex ecological processes governing microbial community dynamics. This interactive regulation might influence the trajectory of plant species and soil microbial communities, facilitating their adaptive development and evolutionary responses.
... The results of previous studies investigated the impacts of seasonal drought on soil microbial biomass are controversial [50][51][52][53][54][55][56][57]. Singh et al. and Raghubanshi reported that soil microbial biomass was most in dry season and least in rainy season in monsoon forests of India, because massive 14 litterfall and abundantly degradable compounds accumulated on the ground and released massive carbon and nutrients to soil microbes, while simultaneously most tree individuals were in the dormant state during dry season resulting in weak competitiveness with soil microbes for nutrients [50,51]. ...
... Singh et al. and Raghubanshi reported that soil microbial biomass was most in dry season and least in rainy season in monsoon forests of India, because massive 14 litterfall and abundantly degradable compounds accumulated on the ground and released massive carbon and nutrients to soil microbes, while simultaneously most tree individuals were in the dormant state during dry season resulting in weak competitiveness with soil microbes for nutrients [50,51]. Barbhuiya et al. and Bargali et al. found that soil MBC was higher in winter (relatively drier and colder) than that in rainy season (relatively wetter and hotter) in the disturbed tropical wetevergreen forest in Arunachal Pradesh of northeastern India and three forest types (Banj-oak forest, Chir-pine forest, and Mixed oak-pine forest) in Central Himalaya of India, because dense plant individuals grew slowly or stopped to grow in winter, resulting in low nutrient demand for plant growth and high nutrient retention in soil for microbial growth and reproduction [52,53]. However, Basu el al. and Manral et al. reported that soil microbial biomass was most in rainy season and least in winter season in Indian deciduous forests and a temperate mixed oak-pine forest of Central Himalaya in India due to higher immobilization of nutrients from decomposing litter by microbes as the decomposition rate of litter and microbial activity are at their peak during the rainy period [54,55]. ...
Severe seasonal droughts driven by global climate change significantly alter the cycling of carbon and nutrients in forest ecosystems through disturbing plant physiology and phenology, soil physicochemical properties, and soil microbial activity. While, the investigation into the impacts of floor mass and plant roots on soil microbial biomass within the context of recurrent seasonal droughts is still rare. To investigate the environmental determinants governing soil microbial biomass with the escalating severity of seasonal droughts, we conducted a study on soil microbial biomass in a comprehensive block experiment, which was manipulated to explore the interplay between floor mass and plant roots contributions, crossed with a factorial irrigation treatment, in a montane subtropical moist evergreen broad–leaved forest of southwestern China. Within control and watered plots, we respectively established four experimental subplots with plant roots and floor mass included (R+F+), plant roots included but floor mass excluded (R+F−), plant roots excluded but floor mass included (R−F+), and plant roots and floor mass excluded (R−F−) from June 2019 to May 2023. The study results revealed that soil microbial biomass as well as soil moisture, floor mass, and plant roots showed an apparent single–hump modal within one year. In the comparative analysis of soil microbial biomass fluctuation amplitudes across control and watered plots, a discernible disparity was observed, indicating that significant differences in microbial biomass dynamics between the respective experimental conditions. The pooled data revealed a statistically significant influence of seasonal drought, floor mass, plant roots, and their reciprocal interactions on the soil microbial biomass, highlighting these factors as pivotal determinants of microbial community dynamics. This study elucidates the interactive regulatory mechanisms by which seasonal drought, floor mass, and plant roots collectively modulate soil microbial biomass within tropical and subtropical forests, offering insights into the complex ecological processes governing microbial community dynamics. This interactive regulation might influence the trajectory of plant species and soil microbial communities, facilitating their adaptive development and evolutionary responses.
... The distinct seasonal pattern of SMBC was similar in open and closed Sal mixed forest, the value being highest during monsoon and lowest during pre-monsoon (Fig. 4). Several authors found higher SMBC content during monsoon 51,[81][82][83][84][85] . This might be due to the high temperature and moisture during the monsoon significantly promote the growth of soil microbes and contribute to the soil microbial biomass 51,81,84-87 . ...
Forest soil is crucial in climate change mitigation, food security, and biogeochemical nutrient cycling. Mixed Sal forests enhance soil organic matter, improve nutrient availability, and regulate pH dynamics. However, anthropogenic disturbances, including deforestation and land-use changes, significantly alter forest cover, leading to shifts in soil physicochemical and microbial properties. These impacts necessitate rigorous monitoring and comprehensive assessment. Therefore, we investigated the effects of contrasting conditions- closed (no human activities) and open (human interferences) mixed Sal Forest on the vertical and seasonal dynamics of microbial biomass carbon (SMBC). Results revealed that the closed mixed Sal Forest had significantly higher SMBC than the open mixed Sal Forest across the soil profile (D1–D5) with a strong seasonal effect. Closed mixed Sal Forest had 60% higher SMBC in D1 than open mixed Sal Forest while it reduced with depth and 17.1 to 56.7% higher SMBC in the subsurface to bottom-most soil profile (D2–D5). Moreover, SMBC was higher in the monsoon period in both forests. The SMBC reduced by 24.2 to 45.1% in the post-monsoon period while reduction was more intense in the pre-monsoon period (48.1 to 68.2%) compared to the monsoon period under closed mixed Sal Forest. Similarly, the decline was more intense in the open mixed Sal Forest, where SMBC declined 12.1 to 54% in the post-monsoon period and 56.1 to 76.2% in the pre-monsoon period compared to the monsoon period. The study indicates that human interference in mixed Sal forests leads to loss of forest cover, negatively affecting microbiological properties and reducing soil fertility, which weakens the forest’s resilience to climate change. Additionally, SMBC exhibits seasonal variations, reflecting responses to environmental conditions. These results underline the need to reduce human disturbances and enhance forest conservation strategies to ensure soil sustainability and ecosystem stability.
... Further, such variations were also governed by locality factors (Bargali et al., 1993;Bisht et al., 2022). It was observed that under disturbed habitat there is significant alteration in the bioclimatic conditions resulting into heterogenous nature of soil along with their attributes (Bargali et al., 2018;Baumler, 2015). The pH value reflected lesser variation among the four studied sites in the present investigation. ...
Plantation forestry is an important aspect in the field of restoration ecology which has both positive and negative implications. Selection of the species based on soil condition, site compatibility and nature of the species along with its performance is an important context to explore on global basis. Present was carried out with the objective to compare the phytosociology of plantation and natural forests along with their inter-relationship with the soil attributes. The present investigation includes random sampling (quadrat study) within the permanent plot of 1 hectare to measure the structure and diversity of tree, seedling and sampling followed by litter biomass and soil. Soil sampling was done from the respective sites at variable soil depths. The four vegetation stands includes teak, Mangium, Eucalyptus plantation along with natural Sal forests. Results revealed that density values of trees, saplings and seedlings varied from 140 to 1530 individual ha⁻¹, 50–1360 individual ha⁻¹ and 40–300 individual ha⁻¹. The tree, sapling and seedling basal area values were ranged from 1.280 to 80.99 m² ha⁻¹, 0.196–6.012 m² ha⁻¹ and 0.00023–0.13 m² ha⁻¹, respectively. Shannon index value of tree species ranged from 0.101 to 1.434 among the four study sites. Nitrogen, phosphorus and potassium level of soil reflects a significant level of variation among the various sites and soil depths. The salient findings includes that the pH value of natural forest and plantation soil to be acidic as the pH value ranged between 5.55 and 6.25 for the soil depths. Organic carbon was elevated in natural forests compared to plantation sites. Iron, manganese and copper level were highest in Eucalyptus plantation than other sites. The major outcome reflects the importance of soil parameters and phytosociological considerations for restoration of soil habitat. It would also provide an insight on the site quality along with necessary information on ecosystem services by various vegetation stands. Such intensive monitoring of different vegetation stands is highly recommended to procure the benefit in terms of harvestable products, C sink and productivity of the stand. The major significance of the study is to understand and utilize the role of plantation forests in terms of harvestable products, C reserve and productivity as well as proper selection of species along with site quality can be essential for ecological sustainability.
... Finally, we expected to find some influence of vegetation patches on the MBC in agreement with some authors that have identified differences in the microbial biomass among tree species for instance (Babur et al. 2021;Bargali et al. 2018). However, we only detected a certain tendency when considering exclusively the data from the pre-burning sampling. ...
Background and Aims
Prescribed burning is a widely used management technique, often employed to restore grasslands affected by woody plants encroachment. However, its interaction with pre-existing plant species in influencing soil properties remains unclear.
Methods
We conducted a diachronic soil survey to assess the evolution of several soil properties in the mid-term (up to 18 months) after burning, including physico-chemical parameters and microbial biomass carbon on soils under vegetation patches of different plant functional types and life forms. Vegetation patches included Ericaceae and legume shrubs, ferns, and biocrusts dominated by lichens. Soil samples were taken pre-burning, immediately after burning and 9 and 18 months after.
Results
Our findings indicate that while some soil properties returned to pre-burning levels in the mid-term (i. e., soil cations and NH4⁺), others, such as available phosphorous (P Olsen), exhibited a significant decline that persisted even 18 months later. Furthermore, soils under legumes initially displayed higher levels of soil carbon and nitrogen compared to other vegetation patches, but this distinction diminished over time. This was likely due to legumes’ susceptibility to fire damage, in contrast to the greater resilience of Ericaceae shrubs.
Conclusion
Our study highlights the complex vegetation patch-dependent effects of prescribed burning on soil properties. While legumes initially enhance soil carbon and nitrogen, their contribution decreases over time due to fire sensitivity. Some soil parameters recover in the mid-term, but nutrients like available phosphorus continue to decline. Fire management strategies should consider plant diversity and recovery time to mitigate soil fertility loss.
... The soil results in this study indicated a significant depth-wise variation of the physico-chemical properties among the forest communities. In the highly dissected landscapes of mountainous ecosystems, bioclimatic conditions change rapidly and vary within short distances, resulting in a pronounced heterogeneity of soils and their chemical, physical, and biological properties (Bargali et al., 2018;Fartyal et al., 2025). Physico-chemical properties of soils vary in space and time because of variations in topography, climate, weathering processes, vegetation cover, and microbial activities (Paudel and Sah, 2003;Bargali et al., 2019;Manral et al., 2022) and several other biotic and abiotic factors (Manral et al., 2020;Pandey et al., 2024). ...
The Himalayas are a crucial centre of biological diversity, supporting a wide range of habitats of floral and faunal communities. Conserving this ecosystem is vital for sustaining life on Earth, including human well-being. Today, maintaining forest ecosystems in the Indian Himalayan Region (IHR) is indispensable not only for the endemic species, but also for the conservation of global biodiversity. The current study covers Talra Wildlife Sanctuary of northwest Himalaya to quantify the biomass and carbon stock in the conifer and broadleaved forest. The data acquisition was performed through random sampling using 50 × 50 m plots along the different altitudinal gradients. The plants having a diameter at breast height (dbh) >10 cm at a 1.37 girth height were identified, enumerated and measured. The result showed that a total of 14 forest communities were specified based on IVI. The total carbon stock values were found to be varied consistently from 131.5 to 357.7 Mg ha-1 in the TWS. The Picea smithiana-Abies pindrow (Ps-Ap) mixed forest community contained a highest amount of carbon stock, 357.7 ± 48.3 Mg ha-1 ; followed by Picea smithiana (Ps) and Abies Pindrow (Ap) dominant, respectively. The understory biomass was also found in a range from 2.10 to 4.4 Mg ha-1 (avg. 3.34 ± 0.66Mg ha-1). The litter biomass was in a range of 1.2-2.9 Mg ha-1 (avg. 2.04 ± 0.48 Mg ha-1). Soil properties showed that on the top layer (0-15 cm), soil moisture (%) and soil organic carbon (%) were 30.2 ± 4.7 (%) and 2.9 ± 0.55 (%), whereas 21.3 ± 4.8 (%) and 1.9 ± 0.53 (%), respectively, at a depth of 15-30 cm. The correlation coefficient indicated a positive correlation (r = 0.85; p < 0.05) between tree carbon stock and tree density.
... Several studies have integrated climate, soil and stand structure into tree allometric models (Cysneiros et al. 2021;Feldpausch et al. 2011;Le Goff and Ottorini 2022;Zhang et al. 2019) or multiple regression models (Huang et al. 2020;Jian et al. 2022;Ma et al. 2023;Zhang et al. 2019). This is because the bioclimatic conditions change rapidly with the altitude in the highly dissected landscapes and may vary within short distances resulting in a pronounced heterogeneity of soil types (Bäumler 2015;Malik and Haq 2022;Pandey et al. 2024) hence influence the distribution of vegetation types (Bargali et al. 2018;Buron et al. 2024;Manral et al. 2023). However, some independent variables are not statistically significant in the allometric or multiple regression models when a complete regression was performed (e.g. ...
Tree allometric models based on height (H) and diameter (D) are the most commonly used method to estimate forest biomass. Environments and stand characteristics are recognized to affect tree allometries. However, few studies have focused on how to incorporate these effects into allometric models, which restricts the use of these models in a wide domain. Adopting the power-law function Y=aGb as a basic model where Y is either tree height or biomass and the corresponding G is tree diameter D at breast height or D2H, we developed a two-step approximation procedure to quantify the effects of environments and stand characteristics on allometric coefficients a and b for Cunninghamia lanceolata and Pinus forest in China. Results show that most of the allometric coefficients are dependent on stand characteristics for C. lanceolata forest, and on mean annual temperature, stand age and latitude for Pinus forest. The allometric models via the two-step approximation Y=fα+αjxjGfβ+βixi (xj or xi are key drivers associated with environments and stand characteristics. α, αj, β and βi are regression coefficients) considerably improved the accuracy of tree height and biomass estimation. Compared to the basic model, the second approximation models significantly reduced the mean absolute bias between the observed and computed values by 25–34% for C. lanceolata and by 21–26% for Pinus forest, respectively. Our results highlight the necessity of incorporating environments and stand characteristics into the allometric models and provide a universal method to accurately estimate H-D-based tree biomass across a wider domain.
... Even though the standing biomass of microbes in soil is small, its rapid turnover ensures that microbial necromass can contribute a substantial portion (> 50%) of stable soil organic C in many cases (Crowther et al. 2015;Wang et al. 2021a;Hou et al. 2024). Given this importance of MBC, understanding the mechanisms controlling MBC accumulation is critical for managing soil C storage and mitigating global climate change (Bargali et al. 2018;Patoine et al. 2022). ...
Background and aims
Microbial biomass carbon (MBC) has a significant contribution to soil carbon (C) pool. It has been suggested that plant input, soil C and nutrient condition, and microbial characteristic play crucial roles in MBC accumulation. However, the primary driver of MBC accumulation remains uncertain.
Methods
To fill this knowledge gap, we conducted a greenhouse ¹³CO2 labelling experiment by planting three pioneer species (Pinus tabuliformis, Betula platyphylla, Populus purdomii) in soils collected from three different depths, i.e., top-soil (0–10 cm), mid-soil (10–30 cm), and deep-soil (30–100 cm).
Results
We found that MB¹³C positively correlated with plant aboveground and belowground ¹³C. The effects of plant ¹³C on MBC accumulation were mainly mediated by fungal diversity and composition. Specifically, mycorrhizal fungi (e.g., Peziza) and toxigenic genera (e.g., Fusarium and Penicillium) were identified as crucial fungal taxa. Notably, plant ¹³C allocation (aboveground ¹³C, belowground ¹³C, proportion of aboveground ¹³C, and proportion of belowground ¹³C) explained a larger proportion (17.50%) of MB¹³C variation among treatments than did soil available phosphorus contents and microbial community structure (fungal diversity and composition) (1.98%).
Conclusion
Our study suggests that plant inputs are major determinants of soil C storage, as plant C allocation was identified as the primary driver of MBC accumulation. Given the different roles of fungi and bacteria, separating fungal and bacterial biomass C can refine our understanding of MBC accumulation.
... However, the soils today have been degraded because of anthropogenic disturbances and have become a global issue. This issue is more prevalent in developing countries having mountainous gradient (Bargali et al., 2018;Manral et al., 2020) where rapid land use transformation is taking place. The altitude of a place profoundly affects the soil's inherent fertility and runoff-erosion behavior (Bowman et al., 2002). ...
Present investigation was executed during 2020-21 in the Department of Soil Science, SAS, Nagaland University, Medziphema to study altitudinal and land use impact on soil characteristics. Altogether fifty-six soil samples were collected from fourteen villages (seven villages each from < 200 m and > 300 m altitudes) of Dimapur district, Nagaland. From each village four soil samples (two each from cultivated and forest land use) collected and analyzed for physicochemical properties, fertility status and soil acidity components. Results revealed that irrespective of land use soil pH ranged from 4.30-5.20 and 4.40-5.29 in low (<200 m) and high (>300 m) altitude soils, respectively, indicated strongly to moderately acidic soil reaction, while electrical conductivity (EC) reported alike under both altitude soils. Slightly low bulk density and particle density noticed in high altitude and forest soils. Altitude and land use systems influenced remarkably CEC of soils and more values found in high altitude and forest soils. In general soils observed high in organic carbon, DTPA extractable Cu, Fe and Mn, medium in available N, K and Zn and low to medium in available P and S. Noticeable high amount of OC, available N, P, K and S found in high altitude soils. Minutely less concentration of micronutrients observed in high altitude soils. Forest soils showed elevated amount of OC, macro and micronutrients and lower values of bulk density. Reasonable quantity of acidity components reported in these soils and accounted for severe acidity problem. Low quantum of acidity components reported in high altitude and forest soils. Soil pH had negative significant correlation with soil acidity components. Both macro and micro nutrients significantly and positively correlated with OC. CEC had significant negative correlation with BD and positive with organic carbon. Therefore, regular monitoring of soil health and balanced nutrient addition through manures and fertilizers is essential for sustainable crop production.
... Bioclimatic conditions in Himalayan ecosystems fluctuate rapidly over short distances due to the highly fragmented landscape [35,36]. This variability can significantly impact vegetation types and their roles in these delicate ecosystems [8]. ...
Ecosystem functioning and management are primarily concerned with addressing climate change and biodiversity loss, which are closely linked to carbon stock and species diversity. This research aimed to quantify forest understory (shrub and herb) diversity, tree biomass and carbon sequestration in the Binsar Wildlife Sanctuary. Using random sampling methods, data were gathered from six distinct forest communities. The study identified 271 vascular plants from 208 genera and 74 families. A notable positive correlation (r² = 0.085, p < 0.05) was observed between total tree density and total tree basal area (TBA), shrub density (r² = 0.09), tree diversity (D) (r² = 0.58), shrub diversity (r² = 0.81), and tree species richness (SR) (r² = 0.96). Conversely, a negative correlation was found with the concentration of tree dominance (CD) (r² = 0.43). The Quercus leucotrichophora, Rhododendron arboreum and Quercus floribunda (QL-RA-QF) community(higher altitudinal zone) exhibited the highest tree biomass (568.8 Mg ha⁻¹), while the (Pinus roxburghii and Quercus leucotrichophora) PR-QL (N) community (lower altitudinal zone) in the north aspect showed the lowest (265.7 Mg ha⁻¹). Carbon sequestration was highest in the Quercus leucotrichophora, Quercus floribunda and Rhododendron arboreum (QL-QF-RA) (higher altitudinal zone) community (7.48 Mg ha⁻¹ yr⁻¹) and lowest in the PR-QL (S) (middle altitudinal zone) community in the south aspect (5.5 Mg ha⁻¹ yr⁻¹). The relationships between carbon stock and various functional parameters such as tree density, total basal area of tree and diversity of tree showed significant positive correlations. The findings of the study revealed significant variations in the structural attributes of trees, shrubs and herbs across different forest stands along altitudinal gradients. This current study’s results highlighted the significance of wildlife sanctuaries, which not only aid in wildlife preservation but also provide compelling evidence supporting forest management practices that promote the planting of multiple vegetation layers in landscape restoration as a means to enhance biodiversity and increase resilience to climate change. Further, comprehending the carbon storage mechanisms of these forests will be critical for developing environmental management strategies aimed at alleviating the impacts of climate change in the years to come.
... Limited understanding of forest fire ecology, socioeconomics, and cultural impacts hampers effective forest resource management and climate change mitigation (Saha and Howe, 2003;Kodandapani et al. 2008). Uttarakhand, specifically, has been the subject of several studies exploring various facets of forest fires, including fire history, ecological impacts, and conservation threats (Semwal and Mehta, 1996;Sharma and Rikhari, 1997;Rikhari et al. 1999;Bhandari et al. 2012;Singh et al. 2016;Bargali et al. 2018). These studies provide crucial insights for policymaking and conservation efforts. ...
This study investigates forest fire dynamics and their implications for management in the Uttarakhand Himalaya region. Utilizing remote sensing analysis, field surveys, and socio-economic assessments, the research aims to understand the spatial and temporal patterns of fires, assess their impact on vegetation, soil properties, and biodiversity, and propose effective management strategies. Results reveal a significant increase in fire frequency and severity, with a 25% rise in fire occurrences observed over the past decade. High-intensity fires caused extensive damage to vegetation, with a 40% reduction in tree density observed in severely affected areas. Soil organic matter loss due to fires averages at 15%, threatening ecosystem health and resilience. However, opportunities for fire management exist, including prescribed burning and community-based prevention programs. Policy recommendations emphasize the importance of integrating ecological and socio-economic perspectives into fire management strategies to promote ecosystem resilience and community adaptation. This study contributes valuable insights for policymakers, forest managers, and local communities to develop science-based fire management policies and practices, ultimately fostering sustainable forest management and fire risk reduction in the Uttarakhand Himalaya region.
... Climate factors and resource availability impact species distribution, structure, and ecosystem functioning (K. Bargali et al., 2018;Hansen et al., 2001). By transcending traditional economic indicators, GEP aims to encapsulate the multifaceted aspects of ecological health and sustainable development. ...
This study presents an assessment of the Gross Environment Product (GEP) in Uttarakhand, India, evaluating the region's human efforts towards the ecology. Research examines the human efforts being made towards Uttarakhand's air, water, soil, and forest, balancing economic development with environmental sustainability. The GEP equation aggregates diverse environmental indicators to assess ecological efforts being made, showing substantial improvements from 2020 to 2022. Results of the analysis in Uttarakhand shows that Air GEP improved significantly, Soil GEP rose with successful organic farming transitions, Water GEP reflected enhanced conservation efforts, and Forest GEP highlighted effective afforestation measures. The study concludes that strategic sustainable practices can enable ecosystems in Uttarakhand to thrive under human pressures, advocating for the inclusion of GEP in environmental governance for evidence-based decision-making and promoting sustainable development globally. The paper also concludes that though a positive outlook is seen in Uttarakhand GEP but when compared to the pressure on economic activities the efforts needs to increase substantially.
... As altitude rises and temperature decreases, microbial activity diminishes, leading to reduced availability of carbon and nutrients in the soil, as documented by Fierer et al. (2011). These results further emphasize the connection between MBC and environmental factors such as soil moisture, vegetation diversity and nutrient cycling, as suggested by Bargali et al. (2018). ...
... Studies about species-specific plant-soil feedbacks using grasses have shown that plant legacies alter soil OM mineralization, soil respiration rates, and may have long-lasting effects on soil OM that persist even after plant removal (Connell et al. 2021). In forest soils, microbial biomass is sustained by vegetation cover and varied according to tree diversity (Bargali et al. 2018). ...
Plants can modify soil properties over time through interactions with soil microorganisms, creating a legacy that may influence subsequent plant growth. This study investigates how soil vegetation covers affect growth and nutrient uptake and phosphorus (P) and nitrogen (N)use efficiencies in two eucalypt species, and the impact of new plant cultivation on soil microbial traits. Using a greenhouse microcosm experiment, we compared soils from a 20-year eucalypt plantation (Euc) and secondary vegetation (Sec) covers, cultivated for five months with Eucalyptus grandis, E. globulus, or left uncultivated. We measured plant growth, P and N concentrations, root and soil enzyme potential activities, and soil properties. Results showed that E. globulus plants in Euc soil had 23% higher shoot biomass production and 27% greater P uptake efficiency compared to plants in Sec soil. Both eucalypt species showed improved P and N use efficiencies in Euc soils, suggesting beneficial soil legacy effects. Furthermore, microbial traits related to arbuscular mycorrhizal (AM) fungi persisted partially in Sec soils, suggesting a beneficial AM fungal legacy for new eucalypt cultivation. The potential activity of enzymes associated with soil carbon and sulfur cycles was clearly influenced by plant presence, whereas enzymes related to the P cycle maintained their potential activity regardless of plant presence, indicating a lasting soil legacy for P mineralization enzymes. The results highlight the role of plant-soil feedback in nutrient utilization and suggest that soil management strategies should consider past vegetation to enhance sustainable eucalypt production.
... Due to the variations in the content of the litter and the pace of root turnover, the microbes are extremely sensitive to the changes in land use (Hooper & Vitousek, 1998;Zuniga-Gonzalez & Caballero-Hernandez, 2022). Numerous researchers from across the world have studied the C stored in soil microbial biomass in various LUS (Fang et al., 2014;Bargali et al., 2018;Padalia et al., 2018;Soleimani et al., 2019), but there have only been a few prior investigations on microbials biomass C (MBC) from the north-western Himalayas. These highland ecosystems are, according to current estimates, more vulnerable to climate change (Rajput et al., 2017;Singh et al., 2018b;Bhardwaj et al., 2022;Bhardwaj et al., 2023). ...
The evaluation of tree-based land-use systems (LUS) such as forests and agroforestry systems is crucial for mitigating and restraining regional and global climate change since these land use systems have a higher potential for carbon (C) sequestration than the other land use systems. In this context, the present study was conducted in the mid hills of the north-western Himalayas to assess the C stored in biomass and soil under different LUS. The experiments were laid out in Randomized Block Design (Factorial). For the study, the two altitudinal gradients (914–1200 m a.m.s.l. and 1201–1500 m. a.m.s.l.) were taken into consideration. The common LUS in both altitudinal ranges, namely agriculture, horticulture, agrisilviculture, silvipasture, agri-horticulture, agri-horti-silviculture, forest and grassland, were chosen for the study. The forest land use system recorded the maximum aboveground biomass (AG-B) C (99.03 t ha⁻¹); belowground biomass (BG-B) C (25.69 t ha⁻¹) and total biomass (TB) C (124.48 t ha⁻¹), that was subsequently followed by silvipasture, agri-horti-silviculture, agrisilviculture, agri-horticulture, horticulture, agriculture and grassland. The absence of organic matter supplies and intensive land management techniques like tillage and ploughing of the soil might have reduced the soil fertility and microbial activity, as verified by the low SOC and MBC in agriculture. The vegetation C density was also significantly influenced by the altitudinal range. Forest and silvipastural system were identified as the sustainable LUS for vegetation C storage, but among the agroforestry systems, the highest C density was recorded in agri-horticulture whereas, grassland displayed the least C density. Agroforestry systems, particularly agrihorticulture, showed 1.27 times greater C storage in soil than agriculture and mitigated 27.36% greater CO2 than agriculture, followed by agri-horti-silviculture (1.24 times greater SOC storage and 24.75% higher CO2 mitigation). Along the altitudinal range, the soil C density followed an increasing trend. These findings have practical implications for sustainable land use planning, emphasizing the potential of agroforestry systems such as agrihorticulture for mitigating climate change by enhancing C storage in these ecosystems.
... MBC is also a primary driver of soil N mineralization and as such plays an important role in nutrient cycling and organic matter decomposition [9][10][11]. Because MBC forms a reservoir of unstable, plant-available nutrients [12], understanding the dynamics of this pool is essential for understanding soil C cycling, C balance, and biochemical properties [13,14]. Importantly, the size of the MBC pool and its fluxes are often used in evaluations of soil fertility [15][16][17], soil effective nutrient status, and biological activity. ...
Most studies about the effects of N addition on soil microbial biomass evaluate soil microbial and physicochemical characteristics using single-test methods, and these studies have not been integrated and analyzed to comprehensively assess the impact of N fertilization on soil microbial biomass. Here, we conduct a meta-analysis to analyze the results of 86 studies characterizing how soil microbial biomass C (MBC), N (MBN), and P (MBP) pools respond to exogenous N addition across multiple land use types. We found that low N addition (5–50 kg/hm²) rates significantly affect soil microbial biomass, mainly by increasing MBC but also by decreasing MBP and significantly increasing MBC/MBP. N addition affects soil physicochemical properties, significantly reducing pH and significantly increasing the soil dissolved organic N and inorganic N content. Our analysis also revealed that the effects of N application vary across ecosystems. N addition significantly decreases MBP and total P in planted forests but does not significantly affect soil microbial biomass in grasslands. In farmland soil, N addition significantly increases total P, NH4⁺, NO3⁻, MBN, and MBP but significantly decreases pH. Although N addition can strongly influence soil microbial biomass, its effects are modulated by ecosystem type. The addition of N can negatively affect MBC, MBN, and MBP in natural forest ecosystems, thereby altering global ecosystem balance.
... In highly dissected mountain landscapes, bioclimatic conditions change rapidly and often vary within short distances, resulting in a pronounced heterogeneity of soils and their physical, chemical (Bäumler 2015; Bargali et al. 2019) and biological characteristics (Manral et al. 2020(Manral et al. , 2022. This directly affects the vegetation types and their functional traits (Bargali et al. 2018;Karki et al. 2022). In addition, interspecific and intraspecific variations in PFTs enable a species to adapt to diverse abiotic and biotic environments (Cornwell et al. 2006;Cornwell and Ackerly 2009;Silva et al. 2019;Awasthi et al. 2022), influence species coexistence (Turcotte and Levine 2016;Yang et al. 2019;Akram et al. 2022;Khatri et al. 2023) and alter ecosystem processes (Crutsinger et al. 2006;Manral et al. 2020;Zhao et al. 2022). ...
The survival strategy of plants is to adjust their functional traits to adapt to the environment. However, these traits and survival strategies of evergreen broad-leaved forest species are not well understood. This study examined 10 leaf functional traits (LFTs) of 70 common plant species in an evergreen broad-leaved forest in Huangshan Mountain to decipher their adaptive strategies. The phylogenetic signals of these LFTs were assessed and phylogenetically independent contrasts (PIC) and correlation analyses were carried out. LFTs were analyzed to determine their CSR (C: competitor, S: stress-tolerator, R: ruderal) strategies. The results show that plant species exhibit different leaf functional traits and ecological strategies (nine strategies were identified; the most abundant were S/CS and S/CSR strategies). Some traits showed significant phylogenetic signals, indicating the effect of phylogeny on LFTs to an extent. Trait variations among species suggest distinct adaptation strategies to environmental changes. The study species were mainly clustered on the C-S strategy axis, with a high S component. Species leaning toward the C-strategy end (e.g., deciduous species), favored a resource acquisition strategy characterized by higher specific leaf area (SLA), greater nutrient contents (N and P), lower leaf dry matter content (LDMC), and reduced nutrient utilization efficiency (C: N and C: P). Conversely, species closer to the S-strategy end (e.g., evergreen species) usually adopted a resource conservative strategy with trait combinations contrary to those of C-strategy species. Overall, this study corroborated the applicability of the CSR strategy at a local scale and provides insights into the varied trait combinations and ecological strategies employed by plant species to adapt to their environment. These findings contribute to a better understanding of the mechanisms involved in biodiversity maintenance.
... In the highly dissected landscape, bioclimatic conditions change rapidly and could vary within short distances, resulting in a pronounced heterogeneity of soils and their physical, chemical (Baumler, 2015;Padalia et al., 2022) and biological characteristics (Manral et al., 2020). This could directly affect the vegetation types and their functional traits (Bargali et al., 2018;Pandey , 2024). The extensive range of clay can be related to the high variability of the parent material in the region. ...
... In some cases, nutrient excess can lead to decline in plant species diversity and significant changes in the community composition, (Bedford et al., 1999). In the highly fragmented landscapes of disturbed ecosystems bioclimatic conditions change rapidly and may vary within short distances, resulting in a pronounced heterogeneity of soil types and vegetation (Bargali et al., 2018;Bäumler, 2015). The Shannon and Simpson's indices showed higher biodiversity in Huelva compared to Córdoba. ...
Dehesa is a unique ecosystem associated with high biodiversity, that integrates trees, livestock, and pasture, making agro-pastoral production compatible with sustainability. However, in the last few decades, a manifold of factors have caused a decline in tree vitality, density, and coverage, leading to long-term changes in species composition and ecosystem structure. This study aims to determine changes in the diversity of the herbaceous plant community in relation to environmental characteristics, the phytosanitary state of the holm oak (Quercus ilex L. subsp. ballota (Desf.) Samp.), and possible interactions with biotic agents, including Phytophthora cinnamomi. For this purpose, the floristic composition and alpha diversity of the understory were assessed in two dehesa stands in Southern Spain. Additionally, the spatial heterogeneity (beta diversity) patterns of herbaceous plants were evaluated in relation to a climatic gradient and subplot orientation at the regional, plot, tree, and subplot scales. Our findings show that microsite features and climate substantially impact the herbaceous plant community in dehesa stands. Annual precipitation is a crucial factor affecting the diversity and biomass of herbaceous plants on a broader, regional scale, consistent with its role as a limiting factor in the Mediterranean climate. However, site-level differences, such as soil clay content and plot slope angle, positively correlate with plant biodiversity, growth, and richness, varying with the Biodiversity Index considered. Moreover, microsites resulting from the combined effects of plot and tree are the main drivers of dissimilarities between samples, as expressed by beta diversity. Contrary to our initial hypothesis, our results reveal no significant association between tree health and herbaceous biodiversity decline.
... In Warangal District, Telangana State, India, the differentiation in soil properties between forest and agro ecosystems offers valuable insights into ecological dynamics and land management practices. Forest ecosystems, with their natural vegetation and minimal human interference, often show distinct soil characteristics, including higher organic matter content and better soil structure compared to agro ecosystems, where intensive agricultural practices can lead to significant soil alterations (Bargali, et al., 2018;Fauzi et al., 2023). These differences in soil properties affect nutrient cycling, soil stability, and overall ecosystem health, underscoring the need for a thorough understanding of these variations to promote effective land management strategies and conservation practices. ...
This study investigates the physico-chemical properties of soil in agricultural and forest ecosystems within Warangal District, Telangana, to understand how land use affects soil quality across different seasons. The objective was to compare soil pH, moisture, organic carbon, and electrical conductivity between these ecosystems during winter, summer, and monsoon. Soil samples were systematically collected from both ecosystems in each season and analyzed for the aforementioned parameters. The present study was conducted in the Rajanpalle village in Gudur mandal in Warangal district of Telangana state, India. The results reveal that forest soils generally exhibit higher pH, moisture content, and organic carbon levels compared to agricultural soils, reflecting the benefits of natural vegetation and organic matter accumulation. Specifically, forest soils maintain more stable moisture and organic carbon levels, particularly in winter, while agricultural soils show greater variability, especially in organic carbon content, which decreases in summer. Electrical conductivity remains within safe limits for both ecosystems, although agricultural soils have higher conductivity during the monsoon due to increased soluble salts from irrigation and rainfall. These findings underscore the significant impact of land use on soil properties and highlight the importance of implementing sustainable management practices to improve soil health and productivity in agricultural systems while preserving the advantages of forest ecosystems.
... Soil microbial biomass is an indispensable component of soil organic matter and is crucial in nutrient cycling; organic matter dynamics; and, thus, ecosystem services [1,2]. Therefore, microbial community composition is considered an important indicator of soil quality [3,4] and a key ecological factor in rehabilitating degraded ecosystems [2]. ...
The microbial biomass in soil is an active and living constituent of organic matter. It is both a storage pool and a source of plant nutrients that can be used as required. In addition, each microbial indicator evaluates soil quality and health from different perspectives, which are not necessarily very different. This study was conducted to compare some physical, chemical, and biochemical characteristics of the soils of forest (SF) and deforested (SDE) areas located on the slopes of the Kirazlıköprü area, which was previously deforested due to dam construction in Bartın province in northwestern Turkey. Soil samples were taken from the topsoil surface (0–5 cm) to determine the microbial soil characteristics of the SF and SDE sites. The soil microbial biomass N (Nmic) was determined by chloroform fumigation extraction, and the Cmic/Nmic ratio and Nmic/Ntotal percentage were calculated using the original values. Total N, Nmic and Cmic/Nmic values are higher in the forest area. The lowest and highest total N (Ntotal) contents in the SF and SDE soils varied between 1.50 and 3.47 g kg⁻¹ and 0.91 and 1.46 g kg⁻¹, respectively. Similarly, the Nmic contents of the SF and SDE soils varied between 75.56 and 143.42 μg g⁻¹ and 10.40 and 75.96 μg g⁻¹, respectively. A statistical analysis revealed that the mean Ntotal and mean Nmic values differed (p < 0.05) in the SF and SDE soils. The mean Cmic/Nmic values in the SF and SDE soils were 8.79 (±1.65) and 5.64 (±1.09), respectively, and a statistical difference was found between the fields (p < 0.05). Our findings indicate that the soil microbial community structure varies according to the site. As a result, it can be concluded that deforestation and erosion due to dam construction in the area led to the removal of plant nutrients from the soil; deterioration in the amount and activity of microbial biomass; and, consequently, soil losses and degradation of soil quality.
... However, they were lower than those reported for boreal forests by IPCC (2007). In Himalayas, bioclimatic conditions change rapidly and may vary within short distances resulting in a pronounced heterogeneity of soil types and their chemical and physical properties (Bargali et al. 2018). Our study highlighted highest levels of soil organic carbon (SOC), total nitrogen (TN) and potassium (K) across high altitude C. torulosa stands as indicated by positive correlation between elevation and soil nutrient content. ...
Forests play a substantial role in sequestering carbon and regulating the global carbon balance. Himalayan Cypress (Cupressus torulosa D. Don) from an ecological and economic stand point is a least explored evergreen conifer of Central Himalaya that often forms either pure stands or sometimes association with other tree species. However, very little information is known about the carbon sequestration potential of these Cypress stands. Therefore, the main objective of this study was to quantify carbon stocks and carbon sequestration potential of six Cypress stands distributed along the altitudinal gradients of 1600–2500 m asl in Kumaon Central Himalaya. A total of 120 circular plots of 5.65 m radius were laid systematically in six Cypress stands with 20 sample plots in each. Soil physical and chemical properties were also assessed. Results revealed that total tree density and basal area in cypress stand ranged from 440–1050 individuals ha⁻¹ and 30.84–60.79 m² ha⁻¹, respectively. The total carbon stock ranged between 151–285 Mg C ha⁻¹, respectively. Carbon sequestration rate across stands fluctuated between 2.42 and 4.87 Mg C ha⁻¹ yr⁻¹. Soil organic carbon (SOC), total nitrogen (TN) and available potassium (K) levels were higher in high altitude stands. Soil organic carbon (SOC) stock (for soil depth 0-60 cm) ranged from 155.58–398.80 Mg ha⁻¹. Altitude and soil physico-chemical factors showed no significant (p>0.05) impact on carbon stocks of Cypress stands. Overall, the carbon reserves in the soil across stands were 9-57% higher than those in the trees' biomass. These estimates indicate that the value of cypress forests lies not only in their ability to sequester biomass carbon but primarily in their extensive soil carbon reserves. This study provides useful background for future research to assess the trend of carbon sequestration in Cypress stands.
... All the sampling sites differ markedly in physicochemical properties of sediments. Generally, physicochemical properties in sediments vary in space and time because of variation in topography, climate, weathering processes, vegetation cover and microbial activities (Paudel and Sah, 2003;Bargali et al., 2018) and several other biotic and abiotic factors (Bargali et al., 2019, Pandey et al., 2024. In the highly dissected landscapes, bioclimatic conditions change rapidly and may vary within short distances resulting in a pronounced heterogeneity in chemical and physical properties (Baumler, 2015;Vibhuti et al., 2020). ...
Intensive land use change is amongst the major threats of the Indian Himalayan region (IHR). Land use intensifications in the unstable slopes of the fragile environment of IHR affect the ecosystem health and services impacting the global climate. The ecological balance is impacted by the altered demography, natural disasters (flood/drought/earthquake), landslides, soil degradation (erosion/nutrient depletion), forest (primary/secondary) fragmentation, deforestation for agriculture/built environment/monoculture plantations, biodiversity loss, mass tourism etc. The ecosystem productivity is reduced, and the economic progress is affected by the insufficient resource efficiency. Subsistence agriculture is altered, shifting cultivation is intensified and rice terraces are abandoned affecting food security. The IHR is more susceptible to seismic disasters with the intense constructions by old technologies and unskilled practitioners. Therefore, the chapter addresses the ecological aspects of disparate land use intensifications for conservation of resources, sustainable ecosystem services with socio-economic progress of IHR.
Nitrogen and phosphorus (NP) deposition can change the nutrient input of forest ecosystems. The effects of NP deposition on soil aggregate need to be analyzed to propose effective environmental management strategies. In this study, representative Korean pine mixed forests and Korean pine plantations in northeastern China were selected. Soil samples were sieved to obtain four different particle sizes of soil aggregates (> 2, 2–0.25, 0.25–0.053, and < 0.053 mm). Four NP treatments were applied to simulate N and P deposition, and an indoor incubation experiment was conducted over a period of 360 d. Total nitrogen, microbial nitrogen, dissolved organic nitrogen, hydrolyzed nitrogen, NH4+–N, NO3−–N content, and extracellular enzyme activities of NAG, LAP, and AP were determined. Different fractions of N responded differently to NP addition. Lower NP addition had a greater promoting effect on aggregate N compared to higher NP addition. NAG was the main extracellular enzyme affecting N in both forest types. NP addition had a greater effect on the extracellular enzyme activities of the soil aggregates from the Korean pine plantations. These results enhance our understanding of the effects of NP addition on soil nitrogen within temperate forest ecosystems.
This is an Open Access Journal / article distributed under the terms of the Creative Commons Attribution License (CC BY-NC-ND 3.0) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. All rights reserved. In this study, fifty-six soil samples were collected from fourteen villages in the Dimapur district of Nagaland, with seven villages located at altitudes below 200 m and seven above 300 m. Four soil samples were taken from each village, two from cultivated land and two from rainforest areas. The results showed that soil pH ranged between 4.30-5.20 at lower altitudes and 4.40-5.29 at higher altitudes, indicating moderately to strongly acidic conditions. Electrical conductivity (EC) was similar across both altitudes. Bulk density and particle density were slightly lower at higher altitudes and in forest soils. Altitude and land use significantly influenced the cation exchange capacity (CEC), with higher values in forest soils and at greater altitudes. Micronutrient concentrations were marginally lower at higher altitudes. Forest soils exhibited higher levels of organic matter and nutrients, with lower bulk density. Acidity components were found in greater amounts in low-altitude soils, contributing to severe acidity issues. Soil pH had shown a negative value for correlation coefficient(r) with acidic components, while macro and micronutrients were positively correlated with OC. Regular soil health monitoring and balanced nutrient management are recommended for sustainable crop production.
Progressively higher atmospheric nitrogen (N) deposition increasingly affects soil ecosystems' elemental cycling and stability. Biochar (BC) amendment has emerged as a possible means of preserving soil system stability. Nevertheless, the pattern of soil–microbial nutrient cycling and system stability in response to BC after high N deposition in ecologically sensitive regions remains uncertain. Therefore, we investigated the effects of high N (9 g N·m⁻²·a⁻¹), BC (0, 20, 40 t·ha⁻¹), and combinations of the treatments on soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), microbial biomass carbon (MBC), nitrogen (MBN), phosphorus (MBP), microbial entropy (qMB), and stoichiometric imbalance (Cimb:Nimb:Pimb). We found that high N addition decreased topsoil (0–20 cm) TP, C:N, qMBN, and Cimb:Nimb values and increased TN, C:P, N:P, qMBP, Cimb:Pimb, and Nimb:Pimb values. However, BC addition increased 0–40 cm soil qMBC and Nimb:Pimb values and decreased qMBN, Cimb:Nimb, and Cimb:Pimb values. Meanwhile, high BC additions attenuated BC's promotion of soil–microbial nutrients. We observed that a mixture of high N and BC increased the 0–40 cm SOC and TP content, promoted the accumulation of MBN and MBP in the subsoil (20–40 cm), and decreased the topsoil Cimb:Pimb and Nimb:Pimb values compared to high N additions. The impact of high N and BC additions on N and P elements varied significantly between the different soil depths. In addition, redundancy analysis identified C:N, MBC, MBN, and C:P as pivotal factors affecting alterations in soil qMB and stoichiometric imbalance. Overall, adding BC reduced the negative impacts of high N deposition on the stability of soil–microbial systems in the Loess Plateau, suggesting a new approach for managing ecologically fragile areas.
El carbono de biomasa microbiana (CBM) es un indicador biológico utilizado para evaluar el efecto de las prácticas de manejo en suelos agrícolas, debido a la importancia que tienen los microorganismos para intercambiar nutrimentos y energía. En la comunidad de San Miguel Tzinacapan, perteneciente al municipio de Cuetzalan del Progreso en el estado de Puebla, una de las actividades económicas más importantes que se realiza es la producción de café. Sin embargo, los agricultores afirman que en los últimos años la producción a disminuido, al igual que la fertilidad de los suelos, lo que ha traído problemas económicos y de seguridad alimentaria, ya que su producción también es para autoconsumo. Se evalúa la relación que tiene el CBM en tres agrosistemas cafetaleros: el agrosistema (A-1) es un policultivo abonado con pollinaza; el segundo (A-2) a un policultivo abonado con composta; y el tercero (A-3) es un monocultivo convencional de café. Se realizaron dos muestreos de suelos uno durante la temporada de lluvias y otro en la temperada de sequía, para describir los componentes biofísicos y de labranza. Los parámetros físicos y químicos de los suelos se obtuvieron con técnicas estandarizadas y el CBM por el método de fumigación-incubación. El agrosistema A-1 presentó la mayor concentración de materia orgánica (10.6% en secas y 6.49% en lluvias), en carbono orgánico (6.15 %), y cationes de intercambiables principalmente de Ca2+ (42.43 presentó en la época de secas, para el agrosistema A-1, la mayor concentración (0.93 g kg-1), seguido del agrosistema A-2 con 0.18 g kg-1). En cuanto a la salud del suelo el agrosistema A-1 obtuvo los valores más altos (8.6) de los parámetros evaluados en cada agrosistema.
The land-use change from agroforestry (AF) to monoculture-based agriculture has the potential to change soil microbial biomass carbon (MBC). The MBC has been used as an indicator of soil quality as well as to determine the microbial status of soil. The aim of this study was to analyze the distribution of soil MBC across different agroforestry practices (AFPs) at two depths in southern Ethiopia. Soil samples were collected from cropland/parkland, woodlots, home gardens, and trees on soil and water conservation-based AFPs. The MBC was determined using the difference in fumigated and non-fumigated extracted carbon contents. The MBC and soil microbial biomass quotient ( MBQ) were significantly different among the different AFPs (P < 0.05). The highest contents of MBC were reported from homegarden on topsoil (505.36 ± 12.45 mg kg − 1 ) and subsoil (401.88 ± 7.26 mg kg − 1 ) soil depths (surface = 0–30 cm, subsoil = 30–60 cm), followed by woodlot (surface: 464.37 ± 9.19 mg kg − 1 ) and (subsoil: 380.24 ± 6.88 mg kg − 1 ), while the lowest result was registered from the subsoil of the croplands (153.10 ± 46.44 mg kg − 1 ). The higher percentage of MBQ was recorded under the woodlots in topsoil layers (1.48%) and subsoil (1.37%), followed by homegarden (surface = 1.41%, subsoil = 1.25%), while the lowest was found under the cropland in subsoil (0.57%). The highest content of soil organic carbon was found under homegarden in topsoil (3.62%) and subsoil (3.23%) followed by woodlot (topsoil: 3.16%, subsoil: 2.87%) and trees on soil and water conservation structures (topsoil: 2.69%, subsoil: 2.51%), while the lowest value was registered under cropland/parkland AF practices (topsoil: 2.67%, subsoil: 2.46%). The distribution of MBC was significantly related to soil organic carbon in soil depth categories, soil total nitrogen, and soil pH in topsoil. Homegarden and woodlot AFPs were suitable for soil MBC improvement among the different AFPs studied, implying that tree-based systems are important for increasing of MBC and ecosystem stability.
Soil biological characteristics are highly sensitive to land use changes, making them valuable indicators of soil quality. This study assesses the effects of three land use types (agriculture, rangeland, and forest) and elevation variations on soil microbial parameters and their spatial distribution in the Khaneghah region. Standard physicochemical and biological properties of the soil were measured on a total of 72 soil samples collected using systematic and random sampling techniques. Spatial distribution maps of the biological indices were generated using geostatistical techniques, specifically the Kriging method, within a geographic information system (GIS). The results revealed significantly higher values for microbial biomass carbon (MBC = 900 mg Cmic-CO2 kg⁻¹), nitrogen (MBN = 8.97 mg Nmic kg⁻¹), basal respiration (BR = 25.1 mg C-CO2 g⁻¹ day⁻¹), and the total microbial population (MPN = 0.63 × 10⁹ cells g⁻¹) in forest soils compared to rangeland and agricultural soils. The alignment between land use maps and biological index maps reinforced these findings. Although the correlations between biological indices and physicochemical properties were generally weak (positive or negative), organic matter content, field capacity moisture, and silt percentage exhibited a slight positive correlation with most of the microbial indices evaluated. The comparison of soil microbial indices with the digital elevation model map indicated higher levels of MBC, MBN, BR, and MPN at elevated regions. However, the microbial quotient and metabolic quotient (qCO₂) did not show significant changes with increasing elevation. The study also confirmed the effectiveness of Kriging interpolation in mapping specific soil microbial indices, as the correlation between Kriging estimates and measured values at sampling points exceeded 0.2, demonstrating statistical significance at a 5% confidence level.
Soil carbon estimates in the Indian Himalayan region—a global climate change hotspot—primarily rely on the lossy wet oxidation method and predominantly focus on soil organic carbon (SOC), neglecting the soil inorganic carbon (SIC) component. Sensitive and holistic soil carbon estimates are crucial for effective policy planning. By incorporating eight major Central Himalayan forest types along a 3000 m elevational gradient, we report that the acidic Himalayan soil (surface soil pH: 4.74–6.84) of the selected forest types hold up to 31% of the total soil carbon stock as SIC stock. Using soil carbon and soil organic matter assays based on elemental analyzer and the loss-on-ignition method, we established that these Himalayan soils store less than 50% of SOC in SOM, challenging the use of universal factors in the region. The amount of SOC in SOM also showed temporal variability. The machine learning Random Forest algorithm highlighted the influence of SOM and climate variables in regulating the distribution of SOC, microbial biomass carbon, and key carbon cycling soil enzymes. The vertical distribution of SOC was more uniform than that of SIC. We found higher activity of soil carbon-cycling enzymes (dehydrogenase, beta-glucosidase, and phenol oxidase) in the forest types. Sensitive and higher soil carbon estimates substantiate a lower microbial quotient (0.17–1.23 %) than the regional trend. Notably, we explained how seasonal and temporal changes in soil carbon estimations hinder a constant positive soil carbon flux. Meanwhile, the mean surface SOC flux (4.63 Mg C ha−1 yr−1) and SIC flux (1.68 Mg C ha−1 yr−1) indicate that the Himalayan soils have significant potential for carbon sequestration. In conclusion, our research indicates substantial soil organic and inorganic carbon storage in major Central Himalayan forest types, with negative anthropogenic activities posing a clear and present threat to the soil carbon stocks.
Traditional large cardamom agroforestry system in the Indian Eastern Himalayas is known for their important role in soil conservation and fertility management. The present study evaluated the impact of altitude and soil depth on soil organic carbon (SOC) storage and soil nutrient status under this system. Standard analytical methods were adopted for quantifying the soil physico-chemical parameters. We used machine learning (ML) techniques and interpreted the result with a test of correlation followed by a test of statistical significance to evaluate the correlation employing XGBoost, SVR and RFR models. The study reveals altitudinal location significantly influences soil nutrient storage and fertility indices. Among the fertility indices, soil fertility index exhibited inconsistent trend with increasing altitude class while, soil evaluation factor consistently decreased with increasing altitude class. With an overall score of R-square = 0.95 and RMSE = 1.19, the XGBoost model outperformed all others in predicting SOC content. Present study suggests altitudinal gradient plays an important role in soil nutrient management. ML algorithms are crucial in quantifying estimating soil carbon stocks and predicting the carbon sequestering potential of diverse land uses and managements. However, there is need for integrating data from satellite imagery, ground-based sensors, and drone technology with adequate technical expertise for processing and analyzing these multi-modal datasets. Such insights will empower farmers to optimize fertilizer utilization, enhance crop productivity, and implement sustainable soil management practices.
Soil aggregates, which are highly influenced by land conversion, play key roles in driving soil nutrient distribution and microbial colonization. However, the role of soil aggregates in shaping the responses of microbial community composition and multiple ecosystem functions, especially ecosystem multifunctionality (EMF), to land conversion remains poorly understood. In this study, we investigated the impact of the conversion of a longan orchard (LO) to a conventional tea plantation (CTP) and organic tea plantation (OTP) on soil EMF at the aggregate level and explored the underlying mechanism. Our results showed that EMF was significantly reduced in the conventional tea plantation, with 3.44, 1.79, and 1.24 times for large macro-, macro-, and micro-aggregates. In contrast, it was relatively preserved in the organic tea plantation. Notably, micro-aggregates with higher microbial biomass supported more EMF than larger aggregates under the land conversion conditions. The EMF associated with soil aggregates was found to be regulated by the differences in nutrient content and microbial community composition. Random forest analysis, redundancy analysis, and Pearson analysis indicated that both soil nutrient and microbial community composition within soil aggregates jointly determined EMF. This study highlights that soil aggregation influences the stratification of nutrients and microbial communities, which leads to the differing response of aggregate-related EMF to land conversion.
In this study, the impact of cropping systems on phy-sicochemical properties of soil and microbial biomass was evaluated. Soil was collected from four cultivated fields (cropland, crop + single tree species, crop + multiple tree species and homegardens) and one uncultivated (agriculturally discarded) field and analysed. The outcome of the present study indicated that cultivated land squandered about 14% C and 5% N in 8 years of cultivation to the nearby uncultivated land. Soil microbial biomass of cultivated land with multiple tree species (C + mT) was greater than other systems and showed an appreciable seasonal variation. The microbial biomass carbon (C mic) assorted from 166 to 266 μg g-1 and microbial biomass nitrogen (N mic) from 11 to 41 μg g-1. C mic contributed 1.25-1.90% of soil C and N mic 0.83-3.77% of soil N. Among cultivated land, maximum C mic and N mic were reported in C + mT system which suggested that tree plantation in cultivated land has significant positive effects on microbial biomass and other soil properties by shifting natural soil properties under the similar environmental circumstances.
Soil biological health is one of the best indicators for soil fertility thus plays a significant role in sustainability of cropping systems. This study was designed to investigate the impact of different seasonal variations and cropping systems on soil microbial biomass and enzymatic activities in sloppy arid soils. Soil samples were collected from the sloppy soils (high, medium and low height terraces) of Khairimurat areas under wheat (Triticum aestivum)-millet (Pennisetum glaucum) and wheat (Triticum aestivum)-mung bean (Vigna radiate) cropping systems. The results revealed that the soil microbial biomass Carbon (Cmic), Nitrogen (Nmic), Phosphorous (Pmic), soil enzymes such as Dehydrogenase (DH) and Alkaline Phosphatase (AP) activity entirely depends on the soil water availability under both cropping systems at all height terraces. The wheat-mung bean cropping systems stored relatively more Nmic, Pmic, AP (activity) and less Cmic, DH (activity) as compared to wheat-millet cropping systems. Regarding the slope gradient under both cropping patterns, high height terraces had retained more Cmic contents, medium height terraces had shown more DH activity and low height terraces had maintained more Pmic contents. In addition to this, Nmic contents and AP activity remained almost similar in all types of terraces under both cropping patterns. Pertaining to seasonal variations under both cropping patterns, the summer season had shown more Cmic, Nmic, Pmic, DH and AP activity as compared to spring, winter and autumn season in all types of terraces. The soil water contents increased down to depth in all types of terraces under both cropping patterns. However, soil water contents remained heterogeneous in all types of terraces under both cropping patterns. In conclusion, it is suggested that in arid environments, cover crops be included in the cropping system in order to enhance soil biological health.
Citation: Ullah, R., Lone, M. I., Mian, S. M., Ali, S., Ullah, K. S., Sheikh, A. A., & Ali, I. (2012). Impact of seasonal variations and cropping systems on soil microbial biomass and enzymatic activities in slope gradient moisture stressed soils of Punjab-Pakistan. Soil and Environment, 31(1), 21-29.
The microbial biomass of soil is being increasingly recognized as a sensitive indicator of soil quality. Its knowledge is fundamental for sustainable environmental management. This study aimed to determine the impact of different land uses (forest, pasture, and agricultural lands) on soil microbial biomass carbon and nitrogen using the chloroform fumigation extraction (CFE) method. This study also aimed to determine interrelationships between microbial biomass C (Cmic) and N (Nmic) and the physicochemical characteristics of the soil. For this purpose, a total of 45 soil samples were taken from 3 different land uses located in the Aǧdacι Village in Bartιn. Additional core samples were collected from each sample site to determine other physico-chemical characteristics of the soils. The average microbial biomass C were found as 1028.29 μg g-1, 898.47 μg g-1, and 485.10 μg g-1, respectively, for forest, pasture, and agricultural soils. As with microbial biomass C, the average microbial biomass N was found as 129.99 μg g-1, 100.90 μg g-1, and 42.60 μg g-1, respectively, for forest, pasture, and agricultural soils. One-Way ANOVA showed a significant difference in microbial biomass C and N among the study areas. Microbial biomass C and N were shown to be significantly correlated to the physico-chemical properties of the soil, such as organic C, total N, clay, and pH. Present study clearly shows that land use has a significant effect on microbial biomass C and N in soil by altering natural soil characteristics under the same ecological conditions.
The present study was conducted in a tropical dry deciduous forest at Barnawapara wildlife sanctuary, Raipur, Chhattisgarh, India. Leaf litter decomposition and nutrient release were studied in four tree species viz., Shorea robusta C.F. Gaertn.f., Madhuca indica J.F. Gmel., Diospyros melanoxylon Roxb. and Schleichera oleosa (Lour.) Oken. The objectives of the study were to determine the weight loss and nutrient mineralization pattern of leaf litter of these four major species. The weight loss was fastest in S. robusta and slowest in M. indica. Monthly weight loss was positively related (P < 0.05) with the climatic factors (rainfall, temperature and relative humidity) except for M. indica for which the relationship was not significant. Weight remaining was inversely related (P < 0.01) to N and P concentrations, but was positively related to K concentration. The nutrient content in the residual litter decreased continuously with time for all species, except in the case of P for S. robusta and D. melanoxylon. We conclude that S. robusta decomposed at fasters rate followed by D. melanoxylon, S. oleosa and M. indica. The former species also released the two important nutrients (N and P) at a faster rate as compared to the other species. M. indica showed the slowest decomposition rate and nutrient release.
Properties of the top 30 cm of soil under plantations of 1-yr to 8-yr old Eucalyptus (the hybrid E. tereticornis) and in adjacent natural mixed broad-leaved forest were compared in the sub-tropical zone of the central Himalaya. Various soil-physical characteristics decreased with increasing age; soil-chemical properties, notably organic carbon, total N, P and K decreased as a result of reforestation with Eucalyptus and further decreased with increasing age of the plantation.
The soil microbial biomass of soil is being increasing recognized as sensitive indicator of soil quality. Its knowledge is fundamental for sustainable environment management. The soil microbial biomass C, N and P were studied in four different land uses of dry tropical forest of Udaipur, Rajasthan, Western India to assess the influence of abiotic, physico-chemical variables and difference in different land uses (mixed forest, butea plantation, grassland and agricultural lands) on the seasonal variation in soil microbial biomass. Microbial biomass C, N and P were highest during rainy season and lowest during winter in all the four different land use with the exception of microbial N which was lowest in summer in mixed forest and butea plantation. Microbial biomass C and N were shown to be significantly correlated to the abiotic and physico-chemical variables of the soil, such as soil temperature, relative humidity, soil moisture, organic C, total N, clay, and pH. Present study clearly shows that land use has a significant effect on microbial biomass C, N and P in soil by altering natural soil characteristics under the same ecological conditions.
The reconstruction of the landscape history and past environmental fluctuations is a major task with respect to forecasting man or naturally-induced changes. In this context the extent of soil development in fluvial deposits of the Chamkhar Chhu river system in Eastern Bhutan were studied for relative age dating. The deposits represent 25 fluvial terraces up to more than 260 m above the recent river level. We used a set of methods covering physical (soil texture, specific surface area) and chemical (pedogenic oxides, soil development indices) processes, and we calculated solum-weighted means of individual soil parameters to compare different sites, and to minimize problems caused by heterogeneity of the parent materials. The results were maintained by numerical age dating of fossil A horizons. Pedogenic oxides and soil development indices as well as soil texture indicate that soils can be used as proxies of the history of landscape and climate. Local as well as global climate fluctuations are well preserved in the soils despite slope processes inducing reverse-tended soil formation in fluvial deposits of Late Pleistocene origin and older, while soils on fluvial deposits of Holocene age indicate distinct chronosequences (Dorji et al. 2009).
We used the terrestrial ecosystem model “Century” to evaluate the relative roles of water and nitrogen limitation of net primary productivity, spatially and in response to climate variability. Within ecology, there has been considerable confusion and controversy over the large-scale significance of limitation of net primary production (NPP) by nutrients versus biophysical quantities (e.g., heat, water, and sunlight) with considerable evidence supporting both views. The Century model, run to a quasi-steady state condition, predicts “equilibration” of water with nutrient limitation, because carbon fixation and nitrogen fluxes (inputs and losses) are controlled by water fluxes, and the capture of nitrogen into organic matter is governed by carbon fixation. Patterns in the coupled water, nitrogen, and carbon cycles are modified substantially by ecosystem type or species-specific controls over resource use efficiency (water and nitrogen used per unit NPP), detrital chemistry, and soil water holding capacity. We also examined the coupling between water and nutrients during several temperature perturbation experiments. Model experiments forced by satellite-observed temperatures suggest that climate anomalies can result in significant changes to terrestrial carbon dynamics. The cooling associated with the Mount Pinatubo eruption aerosol injection may have transiently increased terrestrial carbon storage. However, because processes in the water, carbon, and nitrogen cycles have different response times, model behavior during the return to steady state following perturbation was complex and extended for decades after 1- to 5-year perturbations. Thus consequences of climate anomalies are influenced by the climatic conditions of the preceding years, and climate-carbon correlations may not be simple to interpret.
Conversion of forests of the humid tropics into pastures and agricultural fields is expected to produce, in the long-term, a decline in soil organic matter content and soil fertility. Changes in microbial biomass (Biomass C, Be) following vegetation removal can provide an early indication for slower, less easily detectable SOM changes. Microbial biomass can also provide an index of soil fertility because it represents an important labile pool of soil nutrients and plays an active role in preventing nutrient loss. There are few published measurements of Be in the humid tropics and fewer of Be changes due to shifts in vegetation cover. We measured Be in two humid tropical soils (an oxic Humitropept at 4.5% C and pH of 5.0 and a fluventic Dystrandept at 2.6% C and pH of 6.4) subjected, for 3 yr, to extreme treatments: soil maintained bare, annual harvest of re-growth, and native 20 yr old secondary vegetation. Both soils showed a similar pattern in total SOM and Be decline following vegetation removal: after 3 yr, total C and N were reduced by 20%. Response of Be was more pronounced. In the bare soil, most of the decline in Be occurred within the first 6 months (to 50% of initial values) and after 15 months. Be appeared to have stabilized at ca 35% of its initial value. Response of Be to the annual harvest treatment was more moderate than to the bare soil treatment. Determining the precise size of microbial biomass is difficult because of variability in time and differences between techniques, but Be values determined by two techniques and on numerous dates were high: in control plots around 2000 (oxic Humitropept) and 1300 (fluventic Dystrandept) μg Cg−1 soil (or 250 and 187 gm−2 after correction for differences in bulk density), which suggests that Be in humid tropical soils can be high. Microbial C represented ca 4% of the total C in the control and declined to ca 1.5% of the total C in the bare soil. Eucaryote:procaryote ratios were close to l for all treatments except in the Fluventic Dystrandept control, which supported a woody vegetation and had a ratio of 3.3. This study demonstrates the dynamic nature of microbial biomass following tropical forest clearing and its potential importance for affecting nutrient loss.
Decomposition of three root litter classes of Quercus leucotrichophora and Pinus roxburghii was studied during 18 months to examine the temporal change in nutrient concentration and mass loss and its spatial pattern and to develop a vegetational model of litter mass loss based on the controls of climate and substrate quality. The experiments involved two forest sites in an altitude of 1600 and 2160m for Quercus and Pine, respectively. In addition a standard root litter was placed on the forest floor of each of the forest site. Litter with greater root diameter tended to be lower in nutrient concentration. Pattern of change of nitrogen concentration differed with diameter. Monthly mean temperature, rainfall and humidity could account for 54–56% of monthly mass loss for both forest sites. Ash free mass loss of fine roots decreased with increasing root diameter. The rate of decomposition was significantly correlated with initial nutrient concentration. Material with higher C/N ratios had a longer duration of immobilisation and in turn a slower release phase.
Investigations focusing on the temperature sensitivity of microbial activity and nutrient turnover in soils improve our understanding of potential effects of global warming. This study investigates the temperature sensitivity of C mineralization, N mineralization, and potential enzyme activities involved in the C and N cycle (tyrosine amino-peptidase, leucine amino-peptidase, ß-glucosidase, ß-xylosidase, N-acetyl-ß-glucosaminidase). Four different study sites in the Austrian alpine zone were selected, and soils were sampled in three seasons (summer, autumn, and winter). A simple first-order exponential equation was used to calculate constant Q10 values for the C and N mineralization over the investigated temperature range (0–30°C). The Q10 values of the C mineralization (average 2.0) for all study sites were significantly higher than for the N mineralization (average 1.7). The Q10 values of both activities were significantly negatively related to a soil organic matter quality index calculated by the ratios of respiration to the organic soil carbon and mineralized N to the total soil nitrogen. The chemical soil properties or microbial biomass did not affect the Q10 values of C and N mineralization. Moreover, the Q10 values showed no distinct pattern according to sampling date, indicating that the substrate quality and other factors are more important. Using a flexible model function, the analysis of relative temperature sensitivity (RTS) showed that the temperature sensitivity of activities increased with decreasing temperature. The C and N mineralization and potential amino-peptidase activities (tyrosine and leucine) showed an almost constant temperature dependence over 0–30°C. In contrast, ß-glucosidase, ß-xylosidase, and N-acetyl-ß-glucosaminidase showed a distinctive increase in temperature sensitivity with decreasing temperature. Low temperature at the winter sampling date caused a greater increase in the RTS of all microbial activities than for the autumn and summer sampling dates. Our results indicate (1) a disproportion of the RTS for potential enzyme activities of the C and N cycle and (2) a disproportion of the RTS for easily degradable C compounds (ß-glucose, ß-xylose) compared with the C mineralization of soil organic matter. Thus temperature may play an important role in regulating the decay of different soil organic matter fractions due to differences in the relative temperature sensitivities of enzyme activities.
AimsNatural secondary forest (NSF) and larch plantation are two of the predominant forest types in Northeast China. However, how the two types of forests compare in sustaining soil quality is not well understood. This study was conducted to determine how natural secondary forest and larch plantation would differ in soil microbial biomass and soil organic matter quality.Methods
Microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), soil organic carbon (SOC) and total nitrogen (TN) in the 0- to 15-cm and 15- to 30-cm soil layers were investigated by making chemical and biological measurements in the montane region of eastern Liaoning Province, Northeast China, during the growing season of 2008 in stands of NSF and Larix olgensis plantation (LOP).Important FindingsWe found that soil MBC and MBN were significantly lower in the LOP than in the NSF. Both MBC and MBN declined significantly with increasing soil depth in the two types of stands. The ratios of MBC to SOC (MBC/SOC) and MBN to TN (MBN/TN) were also significantly lower in the LOP than in the NSF. Moreover, the values of MBC, MBC/SOC, and MBN/TN significantly varied with time and followed a similar pattern during the growing season, all with an apparent peak in summer. Our results indicate that NSF is better in sustaining soil microbial biomass and nutrients than larch plantation in the temperate Northeast China. This calls for cautions in large-scale conversions of the native forests to coniferous plantations as a forest management practice on concerns of sustaining soil productivity.
The large-scale conversion of Amazonian forest to other land-uses is altering carbon (C) stocks in this important eco-region, and these changes will in turn influence global C cycling. In this study, we evaluated changes of forest floor and surface soil C storage caused by converting primary Amazonian forest to tree plantations at the Curuá-Una Forest Reserve, Pará, Brazil. The plantations were established between 1959 and 1973 and they consisted of replicated plots of Pinus caribaea var. hondurensis Barrett and Golfari, Carapa guianensis Aubl., Euxylophora paraensis Hub., and a Leguminosae combination (Parkia multijuga Benth., Dinizia excelsa Ducke, Dalbergia nigra Fr. All. In surface soils (0–20cm), mean C stocks ranged from 7 (P. caribaea) to 11kgm−2 (E. paraensis). Fine litter C inputs ranged from 380gm−2 (E. paraensis) to 513gm−2 (P. caribaea), and forest floor C stocks (fine material) ranged from 359 (E. paraensis) to 542gm−2 (P. caribaea). P. caribaea had the smallest fine root biomass–C (≤2mm diameter) in the forest floor and surface soils (101gm−2). Relative to adjacent terra firme forest, total C stocks in the surface mineral soil, forest floor, and fine roots (live+dead) in the plantations ranged from a net decrease of 13% (P. caribaea) to a net increase of 7% (E. paraensis).
The soil microbial biomass C, N and P were studied in two stands of mixed-oak forest ecosystem of Manipur, North-east India to assess the influence of abiotic variables and difference in forest stand on the seasonal variation in soil microbial biomass. Microbial biomass C, N and P were highest during rainy season and lowest during winter in both the forest stands with the exception of microbial N which was lowest in summer in stand II. Microbial biomass C and P showed a positive significant correlation with abiotic variables, i.e. soil moisture, soil temperature, rainfall, mean air temperature and relative humidity in both the stands. Whereas the microbial N exhibited a positive significant correlation with abiotic variables in stand I, but showed a significant correlation only with soil moisture in stand II. The contribution of microbial C, N and P to total soil organic C, total N and P indicates that microbial biomass is immobilized more in forest stand I in comparison to forest stand II.
The objectives of our research were to describe the seasonal patterns in soil inorganic N and microbial biomass N and to assess the rates of net N mineralization and net nitrification in 29-year-old Mongolian pine (Pinus sylvestris var. mongolica) stands in the south-eastern area of Keerqin Sand Lands, China. The concentrations of soil ammonium-N (NH4+-N), nitrate-N (NO3−-N), and inorganic N as well as the rates of net N mineralization and net nitrification clearly showed seasonal patterns of a bell shape from April to October. However, the seasonal patterns were less obvious for microbial biomass N. Higher NO3−-N concentrations were found in the unfenced, grazed stand and higher NH4+-N concentrations were found in the fenced, ungrazed stand. The rate of cumulative net N mineralization was 55.4kgha−1year−1 in the fenced stand and 33.0kgha−1year−1 in the unfenced stand. Of the annual net N mineralization in the fenced stand, only 33.2% was nitrified to NO3−-N, whereas in the unfenced stand, 62.2% was nitrified. Apparently, N availability components in Mongolian pine stands were significantly affected by the two different management options. Our results suggest that a deficiency in N availability to these Mongolian pine plantations happens in the early part of the annual growing season.
We examined the effects of treefall gap size and soil properties on microbial biomass dynamics in an undisturbed mature-phase
humid subtropical broadleaved forest in north-east India. Canopy gaps had low soil moisture and low microbial biomass suggesting
that belowground dynamics accompanied changes in light resources after canopy opening. High rainfall in the region causes
excessive erosion/leaching of top soil and eventually soil fertility declines in treefall gaps compared to understorey. Soil
microbial population was less during periods when temperature and moisture conditions are low, while it peaked during rainy
season when the litter decomposition rate is at its peak on the forest floor. Greater demand for nutrients by plants during
rainy season (the peak vegetative growth period) limited the availability of nutrients to soil microbes and, therefore, low
microbial C, N and P. Weak correlations were also obtained for the relationships between microbial C, N and P and soil physico–chemical
properties. Gap size did influence the microbial nutrients and their contribution to soil organic carbon, total Kjeldhal nitrogen
and available-P. Contribution of microbial C to soil organic carbon, microbial N to total nitrogen were similar in both treefall
gaps and understorey plots, while the contribution of microbial P to soil available-P was lower in gap compared to the understorey.
These results indicate that any fluctuation in microbial biomass related nutrient cycling processes in conjunction with the
associated microclimate variation may affect the pattern of regeneration of tree seedlings in the gaps and hence be related
with their size.
AimsElevated atmospheric CO2 has the potential to enhance the net primary productivity of terrestrial ecosystems. However, the role of soil microorganisms on soil C cycling following this increased available C remains ambiguous. This study was conducted to determine how quality and quantity of plant litter inputs would affect soil microorganisms and consequently C turnover.Methods
Soil microbial biomass and community structure, bacterial community-level physiological profile, and CO2 emission caused by different substrate C decomposition were investigated using techniques of biological measurements, chemical and stable C isotope analysis, and BIOLOG-ECO microplates in a semiarid grassland ecosystem of northern China in 2006 and 2007 by mixing three contrasting types of plant materials, C3 shoot litter (SC3), C3 root litter (RC3), and C4 shoot litter (SC4), into the 10- to 20-cm soil layer at rates equivalent to 0 (C0), 60 (C60), 120 (C120) and 240 g C m-2 (C240).Important FindingsLitter addition significantly enriched soil microbial biomass C and N and resulted in changes in microbial structure. Principal component analysis of microbial structure clearly differentiated among zero addition, C3-plant-derived litter, and C4-plant-derived litter and among shoot- and root-derived litter of C3 plants; soil microorganisms mainly utilized carbohydrates without litter addition, carboxylic acids with C3-plant-derived litter addition and amino acids with C4-plant-derived litter addition. We also detected stimulated decomposition of older substrate with C4-plant-derived litter inputs. Our results show that both quality and quantity of belowground litter are involved in affecting soil microbial community structure in semiarid grassland ecosystem.
To understand the spatial and temporal dynamics of soil microbial biomass and its role in soil organic matter and nutrient flux in disturbed tropical wet-evergreen forests, we determined soil microbial biomass C, N and P at two soil depths (0–15 and 15–30 cm), along a disturbance gradient in Arunachal Pradesh, northeastern India. Disturbance resulted in considerable increase in air temperature and light intensity in the forest and decline in the soil nutrients concentration, which affected the growth of microbial populations and soil microbial biomass. There were significant correlations between bacterial and fungal populations and microbial biomass C, N and P. Soil microbial population was higher in the undisturbed (UD) forest stand than the disturbed forest stands during post-monsoon and less during rainy season due to heavy rainfall. Greater demand for nutrients by plants during rainy season limited the availability of nutrients to soil microbes and therefore, low microbial biomass C, N and P. Microbial biomass was negatively correlated with soil temperature and pH in all the forest stands. However, there were significant positive relationships among microbial biomass C, N and P. Percentage contribution of microbial C to soil organic C was higher in UD forest, whereas percentage contribution of microbial biomass N and P to total N and total P was higher in the moderately disturbed site than in the highly disturbed (HD) site. These results reveal that the nutrient retention by soil microbial biomass was greater in the selective logged stand and would help in the regeneration of the forest upon protection. On the other hand, the cultivated site (HD) that had the lowest labile fractions of soil organic matter may recover at a slower phase. Further, minimum and maximum microbial biomass C, N and P during rainy and winter seasons suggest the synchronization between nutrient demand for plant growth and nutrient retention in microbial biomass that would help in ecosystem recovery following disturbance.
Assessment of soil quality is an invaluable tool in determining the sustainability and environmental impact of agricultural ecosystems. The study was conducted to assess the quality of the soils under arable cultivation, locally irrigated and non-irrigated, forestry plantations of teak (Tectona grandis Lin.) and gmelina (Gme-lina arborea Roxb.), and cashew (Anacardium occidentale Lin.) plantation agro ecosystems using soil organic carbon (SOC), soil total nitrogen (STN) and soil microbial biomass C (SMBC) and N (SMBN) at Minna in the southern Guinea savanna of Nigeria. Soil samples were collected from soil depths of 0-5 cm and 5-10 cm in all the agro ecosystems and analyzed for physical, chemical and biological properties. All the agro ecosystems had similar loamy soil texture at both depths. The soils have high fertility status in terms of available phosphorus and exchangeable calcium, magnesium and potassium. The irrigated arable land had significantly (P < 0.05) higher SOC and STN in both soil depths than all the other soils due to greater C inputs into the soil and fertilizer application. The cashew plantation soil had the lowest SMBC value of 483 mg kg-1 while teak soil had the highest value of 766 mg kg-1 which was significantly (P < 0.05) different from that of the other soils at the surface layer. At both soil depths, in all the soils, the SMBC/SMBN ratios were >6.6 suggesting fungal domination in all the agroecosystems. The forestry plantation soils had higher SMBC and SMBN as a percentage of SOC and STN respectively than the cultivated arable land soils. Burning for clearing vegetation and poor stocking of forestry plantations may impair the quality of the soil. The study suggests that the locally irrigated agro-ecosystem soil seems to be of better quality than the other agroecosystem soils.
Litters high in cell wall constituents tend to be lower in nutrient concentrations. Relative patterns of change in K and Ca concentrations tended to differ from those of N, P and Na. Monthly rainfall and could account for 25-89% of monthly weight loss of litter on each site. Annual temperature, actual evapotranspiration (AET) and altitude explained, respectively, 48.7%, 53.6% and 49.1% of variability. Measures of cell wall constituents, eg lignin concentration, could account for up to 60% of the variability in weight loss in the first year; however, lignin, as a predictor of weight loss rate, contains considerable information about plant nutrients. In warm temperate and subtropical climates the cell wall constituents seem to be good predictors of weight loss in the first year while in cool temperature to arctic climates, the early stages of decay are prolonged, resulting in good prediction by litter nutrients. -from Authors
Decomposition of leaf litter from 10 woody species was studied using litter bags incubated for 2 yr in 5 forest ecosystems, and Quercus leucotrichophora leaf litter was placed in each forest site to provide uniform substrate quality. Annual weight loss ranged from 47-100% among species. Differences between sites and species were significant. Most species exhibited 2 phases in their nutrient dynamics, a net immobilization phase followed by a net release phase. Net immobilization of N and P occurred in all litter species except Mallotus philippensis, Lyonia ovalifolia and Quercus leucotrichophora, while Ca and K exhibited only a release phase except in Pinus roxburghii and Myrica esculenta, where net immobilization of Ca occurred for a short period. The periods of net immobilization of various nutrients overlapped to a considerable extent. Material with higher initial C:nutrient ratios had a longer duration of immobilization and, in turn, a slower release phase. The critical C:N ratio (at which net release of N occurred), varied from 15:1 to 55:1. Species having higher N contents (1.20-3.04%) had higher weight loss rates. Species having >17% initial lignin accumulated more N. Mean annual temperature, altitude and lignin content were the principal regulating factors for weight loss and nutrient mineralization. -from Authors
Soil microbial activity drives carbon and nutrient cycling in terrestrial ecosystems. Soil microbial biomass is commonly limited by environmental factors and soil carbon availability. We employed plant litter removal, root trenching and stem-girdling treatments to examine the effects of environmental factors, above- and belowground carbon inputs on soil microbial C in a subtropical monsoon forest in southwest China. During the experimental period from July 2006 through April 2007, 2 years after initiation of the treatments, microbial biomass C in the humus layer did not vary with seasonal changes in soil temperature or water content. Mineral soil microbial C decreased throughout the experimental period and varied with soil temperature and water content. Litter removal reduced mineral soil microbial C by 19.0% in the ungirdled plots, but only 4.0% in girdled plots. Root trenching, stem girdling and their interactions influenced microbial C in humus layer. Neither root trenching nor girdling significantly influenced mineral soil microbial C. Mineral soil microbial C correlated with following-month plant litterfall in control plots, but these correlations were not observed in root-trenching plots or girdling plots. Our results suggest that belowground carbon retranslocated from shoots and present in soil organic matter, rather than aboveground fresh plant litter inputs, determines seasonal fluctuation of mineral soil microbial biomass.
In agroecosystems, rich soil biodiversity performs a variety of ecological services and contributes to sustainability of agriculture. In spite of the vast knowledge on this subject globally, the Himalayan mountain agroecosystems remain almost unexplored, and the agriculture is practiced on a subsistence level in the desire of suitable soil fertility management practices. This study was conducted on the soil macrofauna community and its influence on litter decomposition, nutrient release and soil quality in rainfed wheat-paddy cropping systems in two major agroecosystems in the central Himalayan mountains. Following local farmers' practice, Oak leaf litter (agroecosystem-I) and Pine forests leaf litter (agroecosystem-II) were used for farm yard manure (FYM) preparation for soil fertility restoration. Control (traditional cropfields) and treatment (macrofauna excluded plots) were maintained in this study. In both the agroecosystems, 11 soil macrofauna groups were recorded across 0–30 cm soil depths over an annual crop cycle. Total macrofauna density in the rhizosphere zone of agroecosystem-I was significantly greater (P < 0.01) than in agroecosystem-II (2477 vs. 2241 ind m⁻²), and it was particularly significantly greater (P < 0.01) in the top soil (0–10 cm depth) of agroecosystem-I (2321 vs. 1877 ind m⁻²). With regards to macrofauna taxonomic groups and population density our study area falls in the middle range reported for the world (taxonomic groups = 11-22; population density = 1637–9500 ind m⁻²). Decomposition of the Oak and Pine leaf litter was significantly lower (P < 0.01) in macrofauna-excluded litter bags in agroecosystem-I (63.4 vs. 49.4%) than in agroecosystem-II (44.4 vs. 29.2%). Levels of available nutrients (NO3-N,NH4-N, PO4-P and available K) were significantly higher in the soil of control plots than in treatment plots. This study concludes that soil macrofauna plays an important role in litter decomposition and soil quality maintenance, and recommends that nutrient rich Oak leaf litter should be preferred over Pine leaf litter to promote macrofauna diversity and abundance and soil quality enhancement in the rainfed farming of Central Himalaya.
A number of general propositions on soil formation in mountains based on the concept of I.P. Gerasimov of the "autonomous character" of mountain systems and their soil cover is discussed. The following issues are emphasized: the origin of the soil forming rocks in mountain regions, the contribution of denudation processes to soil genesis, and the necessity of the specific approach to soil classification. Geographical regularities in the distribution of mountain soils, their evolution processes, and soil cover changes under the impact of the natural-anthropogenic processes are discussed on the basis of altitudinal zonality types and morphostructural peculiarities of mountain landscapes. The presented materials suggest the necessity to revise the existing concepts of mountain soil formation.
The soils of two forest types i.e., oak (Quercus leucotrichophora A. Camus) and pine (Pinus roxburghii Sargent) were analysed for physico-chemical properties and economic analysis. The collected soil samples from both the forests were analysed for texture, water holding capacity, pH, potassium, phosphorus and nitrogen. The results show that the higher percent of moisture and water holding capacity was in oak forest and lower in pine forest. The forest types indicate that the soil of oak forest was acidic and slightly acidic to pine forest. The average SOC in oak forest was 2.19% followed by 1.63% in pine. The nitrogen for oak and pine forests was 0.15 and 0.19% respectively. The available phosphorus in oak forest was higher (17.99 kg ha -1) than in pine forest (16.88 kg ha -1). The exchangeable potassium was 188.92 kg ha -1 in oak forest and 166.43 kg ha -1 in pine forest. The total nutrients generated by soils, as an ecosystem service in oak and pine forests were calculated for market costs. The total market cost of nutrients in oak was 1372.00 Rs ha -1 and in pine 1227.50 Rs ha -1 . The maximum contribution among the nutrients was of potassium followed by phosphorus and nitrogen in both the forests. The results of the paper conclude that soil is the principal source of ecosystem services which is generating number of other services. Oak forest are rich in nutrients than pine forest. Thus, oak forest should be preferred to protect, enhance their nutrients level for enhancing the forest ecosystem services. [Journal of American Science 2010;6(2):117-122]. (ISSN: 1545-1003).
Soil organic carbon is simultaneously a source and sinks for nutrients and plays a vital role in soil fertility maintenance Soil microbial biomass can be a useful indicator of soil quality and could possibly serve as assessment criteria of successful rehabilitation of ecologically disturbed areas. To assess the impact of restoration on organic carbon and microbial biomass carbon of soil a study has been conducted at rock phosphate mined area, lies in between longitude 77 0 38' to 78 0 20' E and latitude 29 0 35' to 30 0 30' N of Doon Valley. Climate of Maldeota has well demarcated summer, rainy and winter seasons. The soil texture of Maldeota varies from sandy loam to loamy sand. The natural vegetation of the site is represented by tropical dry mixed deciduous forest type. The area was restored way back in 1982. The study site was 26 year old restored mined area having plantation of Acacia catechu and Dalbergia sissoo while adjacent Natural forest area contains dominant tree species of Cassia fistula, Bauhinia vareigata and Flacourtia cataphracta respectively. Results indicated the recovery of soil quality after restoration as the microbial biomass in the restored area was found to be greater as compared to the natural forest.
Background/purpose
Microbial biomass plays an important role in nutrient transformation and conservation of forest and grassland ecosystems. The objective of this study was to determine the microbial biomass among three vegetation types in subalpine mountain forest soils of Taiwan.
Methods
Tatachia is a typical high-altitude subalpine temperate forest ecosystem in Taiwan with an elevation of 1800–3952 m and consists of three vegetation types: spruce, hemlock, and grassland. Three plots were selected in each vegetation type. Soil samples were collected from the organic layer, topsoil, and subsoil. Microbial biomass carbon (Cmic) was determined by the chloroform fumigation–extraction method, and microbial biomass nitrogen (Nmic) was determined from the total nitrogen (Ntot) released during fumigation–extraction. Bacteria, actinomycetes, fungi, cellulolytic microbes, phosphate-solubilizing microbes, and nitrogen-fixing microbes were also counted.
Results
The Cmic and Nmic were highest in the surface soil and declined with the soil depth. These were also highest in spruce soils, followed by in hemlock soils, and were lowest in grassland soils. Cmic and Nmic had the highest values in the spring season and the lowest values in the winter season. Cmic and Nmic had significantly positive correlations with total organic carbon (Corg) and Ntot. Contributions of Cmic and Nmic, respectively, to Corg and Ntot indicated that the microbial biomass was immobilized more in spruce and hemlock soils than in grassland soils. Microbial populations of the tested vegetation types decreased with increasing soil depth.
Conclusion
Cmic and Nmic were high in the organic layer and decreased with the depth of layers. These values were higher for spruce and hemlock soils than for grassland soils. Positive correlations were observed between Cmic and Nmic and between Corg and Ntot.
Methods of determining soil microbial biomass need to be reliable and produce consistent results across soils with a wide range of properties. We investigated the effect of extractant molarity (distilled water and 0.001, 0.01, 0.1, and 0.5 M K2SO4) on the flush of C (i.e. the difference between fumigated and unfumigated subsamples) with the chloroform fumigation–extraction method in soils of different pH. Extraction efficiency of 0.5 M K2SO4 relative to water was dependent upon soil pH. The ratio of extractable C in water to that in 0.5 M K2SO4 for five acidic soils was 1.5±0.3 in unfumigated controls, 1.4±0.2 in fumigated samples, and 1.8±0.7 in fumigated minus control flushes, respectively. Ratios in six alkaline soils were 1.0±0.2, 0.9±0.2, and 0.8±0.2, respectively. Flocculation/dispersion of organic colloids and changes in the diffuse double layer surrounding clay particles are possible reasons for differences in extractable C with changes in extractant molarity and soil pH. Chloroform fumigation–extraction with any of the extractants was less related to soil organic C and potential C and N mineralization during 50 days of incubation (r2=0.51±0.11) than was chloroform fumigation–incubation without subtraction of a control (r2=0.74±0.08). Changes in microbial biomass estimates with changes in extractant molarity and soil pH suggest that chloroform fumigation–extraction may not be reliable in a wide range of soils.
The effects of clearfelling a tropical rainforest and establishing pasture on soil microbial biomass and nitrogen transformations were assayed monthly over 1 yr in three adjacent systems in the central Amazon region: (1) virgin rainforest; (2) slashed-and-burnt forest; and (3) recently established pasture. The amounts of soil organic matter (SOM) and soil microbial biomass-carbon (biomass-C) were substantial in all systems. Total soil-C ranged between 1.9 and 5.2% depending on management and soil layer, whereas biomass-C ranged between 3.5 and 5.3% of total soil-C. The soil biomass-C decreased upon slashing-and-burning to 64% of its original value (1287 μg g−1) in the forest (0–5 cm soil layer) and increased after establishment of pasture to 1290 μg g−1, but remained unchanged in the deeper 5–20 cm soil layer. No significant seasonal variation was measured in any system or soil layer. Soil respiration responded to management like microbial biomass-C but varied significantly over the season with the smallest respiration found in the driest month (October) and the largest respiration at end of the rains in May. Pools of mineral N varied considerably in all systems and soil layers and displayed identical seasonal variations. The forest topsoil contained the highest amounts (on average 47 μg N g−1) and the pasture soil the smallest amounts (on average 24 μg N g−1). The transition of the forest ecosystem to a pasture resulted in increased NO3− concentrations. Net N-mineralization and net NO3− production monitored during short-term laboratory incubations were used as indices of N mineralization and nitrification. No significant differences in N-mineralization indices were measured between systems, but substantial within season variations were recorded in all systems and soil layers. The variations were synchronized in time with extreme net N-mineralization in September and net N-mineralization in October. Significant nitrification indices were measured in all systems. They were identical in the systems, except for small indices found in topsoil of the slashed and burnt area, where, on the other hand, certain localized areas with extreme nitrification rates were detected.
On decrit une serie d'experimentations consistant a mesurer l'augmentation de l'absorbance en U.V. de composes extraits de sols immediatement avant ou apres fumigation pendant des durees diverses jusqu'a 10 jours. Cette methode permet une mesure approximative simple du carbone de la biomasse, mais la methode a la ninhydrine est preferable
Labile soil organic matter (SOM) can sensitively respond to changes in land use and management practices, and has been suggested as an early and sensitive indicator of SOM. However, knowledge of effects of forest vegetation type on labile SOM is still scarce, particularly in subtropical regions. Soil microbial biomass C and N, water-soluble soil organic C and N, and light SOM fraction in four subtropical forests were studied in subtropical China. Forest vegetation type significantly affected labile SOM. Secondary broadleaved forest (SBF) had the highest soil microbial biomass, basal respiration and water-soluble SOM, and the pure Cunninghamia lanceolata plantation (PC) the lowest. Soil microbial biomass C and N and respiration were on average 100%, 104% and 75%, respectively higher in the SBF than in the PC. The influence of vegetation on water-soluble SOM was generally larger in the 0–10cm soil layer than in the 10–20cm. Cold- and hot-water-soluble organic C and N were on average 33–70% higher in the SBF than in the PC. Cold- and hot-soluble soil organic C concentrations in the coniferous-broadleaved mixed plantations were on average 38.1 and 25.0% higher than in the pure coniferous plantation, and cold- and hot-soluble soil total N were 51.4 and 14.1% higher, respectively. Therefore, introducing native broadleaved trees into pure coniferous plantations increased water-soluble SOM. The light SOM fraction (free and occluded) in the 0–10cm soil layer, which ranged from 11.7 to 29.2gkg−1 dry weight of soil, was strongly affected by vegetation. The light fraction soil organic C, expressed as percent of total soil organic C, ranged from 18.3% in the mixed plantations of C. lanceolata and Kalopanax septemlobus to 26.3% in the SBF. In addition, there were strong correlations among soil organic C and labile fractions, suggesting that they were in close association and partly represented similar C pools in soils. Our results indicated that hot-water-soluble method could be a suitable measure for labile SOM in subtropical forest soils.
Soil development of high mountain soils was studied in eastern Nepal with regard to new aspects about the Quaternary history of landscape and climate. The soils were developed in Quaternary glacial deposits, i.e. the lowest clearly identified terminal and lateral moraines of 5 high valleys of the Khumbu and Solu region, all located between 3800 and 4300masl. Particle size analysis, pedogenic iron oxides and weathering indices were used to obtain information on soil development of the different sites. Except for one site no significant differences were found in the extent of soil development indicating that all soils and their corresponding glacial deposits are of similar relative age. In combination with recently published numerical datings of the terminal moraines in one of the high valleys, the age of the deposits could be narrowed down partly correcting former findings. The maximum extent of the last glaciation, if accepted as more or less synchronous to the global Last Glacial Maximum, was less pronounced than previously assumed. However, morphological and pedological findings give evidence of an early phase of Late Pleistocene glaciation further down valley corresponding to new results from High Asia, the Japanese Alps, North Siberia, and the Kamchatka peninsula.
Pedogeochemical analyses were used to study soil development in aeolian deposits overlying moraines and landslide debris in the Imja Drangka valley, a tributary of the Dudh Kosi in the Khumbu Himal, eastern Nepal. Particle size analysis, trace element ratios, iron fractionation and weathering indices based on total element contents were combined with radiocarbon analyses and morphostratigraphical features to obtain information on stratification of the solum, the extent of soil weathering, pre-weathering, and relative or absolute age of the period of deposition and soil development. The results indicate several periods of deposition of loess-like material at least up to 5000m asl, again indicating differences in the age and source of the aeolian deposits, or different extents of weathering independent of recent soil forming processes at the study sites. Several paleosols have developed in these aeolian deposits during the Holocene. A pedogenic overprint by recent pedogenic processes can be seen beyond boundaries of beds within the aeolian deposits. It may complicate the interpretation and correlation of loess–paleosol sequences. Additional data from radiocarbon dating of buried A horizons and charcoal indicate a period of loess accumulation 3000 to 4000 years ago covering older aeolian deposits of early Holocene to Late Pleistocene age.
We investigated the effects of drying–wetting and freezing–thawing cycles on the emission of nitrous oxide, carbon dioxide and methane from intact soil cores from farmed organic soils at sites in Germany, Sweden and Finland. During the first week following wetting or thawing, cores from the German and Swedish sites produced an up to 1000-fold increase in N2O emission rates. The total surplus N2O emission due to the first wetting event ranged between 3 and 140mg N–N2O m−2, and between 13 and 340mg N–N2O m−2 due to the first thawing event but declined following two successive freeze–thaw events. Wetting and thawing produced a greater surplus emission of N2O from grassland sites compared to arable sites. Following wetting, denitrification was responsible for the majority of N2O emission from the German grassland soil while in the German ploughed soil and the Swedish soils denitrification was responsible for less than 60% of the N2O emission. In contrast, following thawing, denitrification was responsible for
Detrital dynamics and microbial nutrient flux due to disturbances such as treefall and tree cutting were studied in a subtropical Pinus kesiya Royle Ex. Gordon forest in north-east India. Disturbance has substantially altered community structure, and therefore soil nutrient status. Natural gap formation has not resulted in significant changes in dry matter, C and N accumulation in litter and fine roots, or in microbial nutrient concentrations. However, there was a significant reduction in all functional parameters in the selectively logged site and soil heap. Soil microbial C, N and P were maximum in the understorey and minimun in the heap. Fine roots and microbial biomass contributed more to nutrient recycling in the ecosystem. N-mineralization was generally higher in the disturbed sites.
Seasonal dynamics of microbial biomass C, N and P were studied in 7-, 13- and 16-year-old regrowths of a disturbed subtropical humid forest in north-east India. Microbial biomass C, N and P were highest during the winter and lowest during the rainy season at both the 0–10 and 10–20 cm sample depths. The surface soil layer (0–10 cm) had significantly higher microbial biomass C, N and P than the subsurface layer (10–20 cm). Microbial biomass C, N and P were highest in the 16-year-old regrowth and lowest in the 7-year-old regrowth, coinciding with highest and lowest clay content and nutrient status of the soil in the 16- and 7-year-old regrowths, respectively. The C/N and C/P ratios in microbial biomass showed a similar trend. Microbial biomass was negatively correlated with soil temperature and pH in all three regrowths.
Factors affecting the compaction susceptibility of South African forestry soils were assessed. Two traditional measures of compaction susceptibility were used: maximum bulk density (ρmbd) determined by the standard Proctor test, defined compactibility, and the compression index using a simple uni-axial test, defined compressibility. Soils were chosen from a broad range of geological and climatic regions and they varied greatly in texture (8 to 66 g 100 g−1 clay) and organic matter content (0.26 to 5.77 g 100 g−1 organic carbon). Soils showed a wide range in ρmbd values, from 1.24 to 2.00 Mg m−3, and this reflected the wide range of particle size distributions and organic matter contents of the soils. Very good correlations were achieved between measures of particle size distribution, particularly clay plus silt and both compactibility and compressibility. Both compactibility and compressibility were significantly correlated with loss-on-ignition (LOI) which is a measure reflecting the combined effects of soil texture and organic matter on soil physical properties. Indices of compaction susceptibility were influenced more by particle size distribution than by organic carbon content. Clear effects of organic carbon on compaction behaviour were only evident for soils with low clay contents (< 25 g 100 g−1. No clear relationship between compactibility and compressibility was found. Compactibility generally increased with decreasing clay plus silt content, whereas compressibility increased up to about 70 g 100 g−1 clay plus silt before decreasing again. It is difficult to define compaction susceptibility solely in terms of indices of compactibility or compressibility particularly as there is no clear relationship between these two properties. A classification system for compaction risk assessment is presented, based on the relationship between compactibility (ρmbd) and LOI, and between clay plus silt content and compressibility.
Microbial biomass is part of the active pool of soil organic matter that plays focal roles in decomposition of organic materials, nutrient cycling and biophysical manipulation of soil structure. We compared two commonly used variants of the chloroform fumigation–incubation method in their relationships with other active, passive and total soil C and N pools in soils from Texas, Georgia, Alberta and British Columbia. The relationship of potential C mineralization with chloroform fumigation–incubation without subtraction of a control was much stronger (r2=0.81±0.10 among five data sets with a total of 844 observations) than with subtraction of a control (r2=0.30±0.22). Similarly, the relationship of soil organic C with chloroform fumigation–incubation without subtraction of a control was better (r2=0.80±0.13) than with subtraction of a control (r2=0.38±0.32). Relationships of net N mineralization, flush of N following fumigation–incubation, flush of CO2-C during the first day following rewetting of dried soil, particulate organic C and N, mean weight diameter of water-stable aggregation and total porosity with chloroform fumigation–incubation were also better without subtraction of a control than with subtraction of a control. In analyses of data taken from published reports, chloroform fumigation–incubation without subtraction of a control was better related with active soil C pools than with subtraction of a control. Chloroform fumigation–incubation without subtraction of a control, unlike that with subtraction of a control, should be considered a more robust method to determine microbial biomass under a wide range of environmental conditions.
The composition and diversity of biotic communities are controlled by the availability of growth-limiting resources. Resource availability for microbial populations in soil is controlled by the amount and types of organic compounds entering soil from plant litter. Because plant communities differ in the amount and type of substrates entering soil, we reasoned that the composition and function of soil microbial communities should differ with the dominant vegetation. We tested this idea by studying two sugar maple (Acer saccharum Marsh.)-dominated and one oak (Quercus spp.)-dominated forest ecosystems in northern Lower Michigan that differ in rates of soil N cycling. We used phospholipid fatty acid (PLFA) analysis to gain insight into microbial community composition, and we used a subset of Biolog GN substrates found in root exudate to assess the metabolic capabilities soil microbial communities. Although microbial biomass did not differ among ecosystems, principal components analysis of bacterial, actinomycetal, and fungal PLFAs clearly separated the microbial communities of the three ecosystems. Similarly, principal components analysis separated microbial communities by differences in growth on carbohydrates, organic acids, and amino acids. Discrimination among microbial communities in the three ecosystems by PLFAs and substrate use occurred in spring, summer, and fall, but the individual PLFAs and substrates contributing to discrimination changed during the growing season. Our results indicate that floristically and edaphically distinct forest ecosystems also differ in microbial community composition and substrate use. This pattern was consistent across the growing season and repeatedly occurred across relatively large land areas.
Soils developed from mica schist in Eastern Nepal (The Himalayas) were investigated. All soil horizons were characterized by high organic carbon and extractable aluminum contents. Chemical and physical analyses indicated andic soil properties. No short-range order minerals could be detected. It is assumed that aluminum is linked to the organic matter, which leads to insolubilization and stabilization of the organic material against microbial degradation. The formation of Al-humus complexes instead of short-range order minerals is preferred if enough Al and water-soluble organic compounds are present. Al-humus complexes are considered responsible for the formation of Andisols from nonvolcanic parent material. The soil is classified as Dystric Haplustand, medial, mesic (US Soil Taxonomy)
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A number of soils are described in the literature as having andic and spodic soil properties, but have developed in nonvolcanic and nonallophanic materials and lack typical Podzol eluvial and illuvial horizons. They cover a wide range of parent materials and different types of climate. They have always been regarded as restricted to small areas. They were assigned to Andisols/Andosols, Podzols/Spodosols, or andic Inceptisols in the WRB and Soil Taxonomy and sometimes also named Cryptopodzols or Lockerbraunerden. Recent soil surveys in Bhutan, E Himalayas, show these soils are widespread at altitudes between 2200-3500 m asl and are spanning several bioclimatic zones. The aim of this study is the detailed characterization of specific properties and processes of formation by physical and chemical analyses, NMR spectroscopy, column experiments, SEM, XRD, and C-14 dating in one of these soils in E central Bhutan. The results indicate advanced soil development with high amounts of oxidic Fe and Al compounds, low bulk densities (partly < 0.5 g cm(-3)), P retention > 85%, and a dominance of Al-hydroxy-interlayered phyllosilicates. Scanning electron microscopy of sand fractions indicate microaggregates highly resistant to dispersion. Column experiments show podzolization with mobilization and translocation of DOM, Fe, and Al. Nuclear-magnetic resonance spectroscopy and C-14 ages of 16,000 BP indicate stabilization of DOM. Applying classification criteria, these soils appear to have andic and spodic features, but are neither Andosols nor Podzols senso strictu. Especially the role of Fe seems to be underestimated with regard to the specific soil-forming processes. Because of their widespread occurrence and distinct properties, we suggest either a simplification of the criteria for existing soil types or a clearly defined separation of volcanic and nonvolcanic/nonallophanic Andosols.