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Changes in Soil Properties, Organic Carbon, and Nutrient Stocks After Land‐Use Change From Forests to Grasslands in Kumaun Himalaya, India
Land Degradation & Development
Abstract
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.
... However, it is higher than the range highlighted by Sharma et al. (2021) in alpine meadows, where BD values were between 0.27 and 0.35 g cm −3 . In contrast, the BD values in this study are lower than those reported by Fartyal et al. (2025) for forest and grassland ecosystems, suggesting variability in BD across different ecosystems and environmental conditions. ...
... These variations in soil properties can be attributed to the soil heterogeneity, which refers to the spatial and temporal variability in soil properties such as soil texture, structure, and nutrient content. Such heterogeneity can influence BD by affecting soil compaction, porosity, and water retention, all of which vary across ecosystems and environmental conditions (Fartyal et al. 2025). ...
Treeline ecotones are ecologically sensitive ecosystems that are increasingly vulnerable to recent global warming and land degradation processes such as soil erosion, nutrient depletion, and organic matter loss. However, little is known about how floral diversity in treeline ecotones responds to changing environmental factors, particularly in the high Himalayan treeline ecotones. The present study examined the potential effects of topographic and edaphic factors on the vegetation structure of treeline ecotones of two mountain summits in Kumaun Himalaya. Using line transects, plots, and quadrats, we recorded 96 plant species from 72 genera and 36 families. Jaccard similarity coefficients revealed varying degrees of similarity in species composition between different aspects and elevations. Beta diversity analysis indicated nestedness as a dominant driver of community composition. Vegetation assessments showed shifts in tree density (ranging from 12.50 to 227.50 individuals per hectare), basal area (ranging from 0.138 to 9.855 square meters per hectare), and dispersion patterns along the elevational gradient. The dominant tree species across all treeline ecotone plots was Rhododendron arboreum . Regeneration was evident, with 69% of trees in smaller girth classes, indicating active recruitment. In addition to vegetation distribution, this study analysed soil characteristics across the treeline ecotones to assess potential land degradation trends. Soil temperature, pH, moisture, and water holding capacity decreased with elevation. South and east aspects had higher temperatures, pH, and phosphorus, while north and west aspects had higher moisture, organic carbon, and nitrogen. Results indicate that decreasing soil moisture, increasing bulk density, and declining total organic carbon at higher elevations and exposed aspects are indicative of degradation processes that may impact long‐term vegetation stability. The significant relationships between soil parameters and species distribution highlight the importance of understanding degradation dynamics in shaping floristic patterns. Non‐metric multidimensional scaling (NMDS) showed distinct clusters of treeline plots based on environmental variables (stress value: 0.17), while canonical correspondence analysis (CCA) demonstrated strong species‐environment correlations, explaining 83.08% of the total inertia. Given the observed soil degradation trends, conservation strategies should prioritize soil stabilization, erosion control, and nutrient depletion to mitigate the risks of ecosystem degradation. This research provides key insights into ecosystem resilience and serves as a foundation for monitoring treeline ecotones under changing environmental conditions.
... These factors influence the carrying capacity of the IHR. The overexploitation of natural resources has created a big gap between the demand and supply of goods and services (Bisht et al., 2023;Fartyal et al., 2025). As a result, the natural habitat and the number of consequential species have shifted to a marginalized scale, which is of grave concern (Gupta et al., 2019;Olokeogun and Kumar, 2020;Mishra et al., 2020;Dhimal et al., 2021;Kumar et al., 2021). ...
... 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.
... Forest gaps formed due to natural disturbances such as treefalls or human activities like logging, play a crucial role in regeneration of the plant species (Brokaw, 1985;Newell et al., 1993;Denslow, 1995). Regeneration in forest ecosystems is assessed by the survival and extent of distribution of seedlings and saplings under varied environmental conditions (Bargali and Bargali, 2016;Mourya et al., 2019;Fartyal et al., 2025). Moreover, regeneration capacity of tree species is vital in maintaining the forest community structure (Bargali et al., 2014) and also in suggesting the possible future perturbations (Hua et al., 2022;Maletha et al., 2022). ...
Gap dynamics is a crucial ecological process in which canopy openings created by disturbances influence structure, regeneration and growth pattern in forest ecosystems. The canopy gaps (an area > 25 m2 opened by the removal of canopy trees) in the forests are usually caused by both anthropogenic and natural stressors, such as logging, treefalls, windstorms, and fires. Though the canopy gaps play an important role in shaping recruitment of the seedlings and hence the forest ecosystem assemblages, little is known about how the gaps have affected the vegetation establishment in the forest ecosystems, particularly in Terai, Nepal. The present study was carried out in core and buffer zone forests of two lowland national parks of Nepal, viz., Parsa National Park and Bardiya National Park, to assess the influence of gap size on the Shorea robusta seedlings’ recruitment and establishment. Altogether 120 gap sites were sampled ranging in size from 71 to 914.5 m2, which were categorized into small gaps (< 200 m2), medium gaps (200-400 m2), and large gaps (> 400 m2). The mean density of S. robusta seedlings was significantly higher in small (1.98 ind. m-2) compared to the medium-sized (1.37 ind. m-2) and large-sized (0.54 ind. m-2) canopy gaps in both core areas and buffer zones. The small gaps provided the most favorable conditions for seedling recruitment in both locations, possibly due to optimum light and nutrient availability. Moreover, regression analysis showed a significant inverse relationship between seedling density and the size of the canopy gaps. These results indicate that the larger gaps are not favorable for the assemblage and recruitment of S. robusta seedlings, which might be due to the feeble seed dispersal ability of the species for longer distances. Forest managers, therefore, are suggested to maintain small gap sizes to foster the natural regeneration of S. robusta in the forest stands of Terai, Nepal.
Keywords: Buffer zone, lowland forests, national parks, seedlings recruitment
... Given that soil pH is a key factor influencing the decomposition of organic matter, particularly in specific vegetation types (Li et al. 2023), the elevation in soil pH observed in this study is likely to play a pivotal role in enhancing the decomposition process of organic matter. The soils generally vary in space and time because of variation in vegetation, topography, climate, weathering processes and microbial activities (Paudel and Sah 1970;Fartyal et al. 2025) and several other biotic and abiotic factors (Pandey et al. 2024). Physico-chemical and biological characteristics of soil therefore vary within short distances according to parent rocks, vegetation types and land use. ...
Vernicia fordii, a tropical and subtropical oil tree species, is highly esteemed for its fruit but yields slow economic returns. To address this, a study was conducted on intercropping Vernicia fordii with Polygonatum odoratum, a Chinese herbal medicine, to investigate its effects on rhizosphere soil microorganisms and potential for accelerated economic gains. Comparisons were drawn with monocultures of both P. odoratum and V. fordii. Utilizing 16S rDNA sequencing analysis, the study unveiled a profound impact of intercropping on the rhizosphere soil microbial community. Specifically, the abundance of certain bacterial communities such as Actinomycetes, Bacteroidetes, and Chloroflexi, as well as fungal communities like Ascomycota and Basidiomycota, underwent significant changes under intercropping conditions. Within the bacterial community, the relative abundance of Actinobacteria, Myxococcola, and Chloroflexi increased notably by approximately 33.3%, 50%, and 50%, respectively, while Proteobacteria and Acidobacteria decreased significantly by 16.7% and 20%, respectively (p < 0.05). Concurrently, Ascomycota and Basidiomycota in the fungal community showed a significant increase in relative abundance by 10% and 5%, respectively. Functional predictions further indicated enhanced metabolic activities related to nitrogen fixation and chitin decomposition.Moreover, intercropping led to a marked increase in soil nutrient content, including organic matter, available potassium, alkaline hydrolyzable nitrogen, and sucrase activity, which are crucial for the advancement of biogeochemical processes. In terms of plant growth, P. odoratum under intercropping exhibited significant advantages, with increased plant height, ground diameter, and biomass. Notably, the ground diameter increased by 9.75% and biomass by 28.8%. Additionally, the chemical composition of P. odoratum underwent changes, with polysaccharides, total flavonoids, and total saponins showing increases of 1%, 32.9%, and 13.9%, respectively, whereas total phenolic content decreased by 19.0% (p < 0.05). In summary, intercropping not only alters the composition and abundance of soil microbial communities and enhances soil nutrient content but also promotes the growth and accumulation of specific chemical components in P. odoratum. These findings have positive implications for agricultural and forestry production, offering valuable insights for improving agricultural efficiency and economic benefits.
Lantana camara L. (Verbenaceae) is a highly invasive species, listed among the top 100 most problematic weeds globally. This study examined the floristic composition, diversity and soil characteristics in Lantana camara dominated forests in three different forest zones of the Kumaun Himalayan region viz. Oak (1324–1813 m above sea level), Pine (1392–1743 m a.s.l.) and Sal (410–584 m a.s.l.). In each zone, three subplots of 0.5 ha (rectangular plot of 50 m × 100 m) were established and within each plot, five 10 m × 10 m quadrats for trees, ten 5 m × 5 m quadrats for shrubs and twenty 1 m × 1 m quadrats for herbs were placed randomly. Tree density was highest in the pine zone (120–140 individuals hectare⁻1) and lowest in oak (40–120 ind. ha⁻1) zone. L. camara density varied significantly, with the highest infestation in the oak zone (17760–30280 ind. ha⁻1), followed by pine (12600–31560 ind. ha⁻1) and sal (6160–15200 ind. ha⁻1). The correlation analysis revealed that soil properties including texture, organic carbon and nitrogen varied significantly among forest zones. Seasonal fluctuations significantly influenced (p < 0.05) herbaceous diversity and richness. Positive correlation between L. camara invasion and soil nutrients indicated a detrimental long-term impact on composition and diversity in the Kumaun Himalayan forests.
Phenology is acknowledged as one of the important traits that contribute significantly to the success of alien species. Differences in the life history traits related to invasive and native vegetation have been shown to influence the success and extent of the plant invasion. Therefore, to obtain this information, we documented and contrasted the duration of key phenological events viz., vegetative, reproductive and senescence between an invasive alien plant species Ageratina adenophora (Sprengel) King and Robinson and associated 29 natives in different habitats viz., Oak, Pine and Cypress forests and grassland. The results indicated vegetative phase and senescence tends to be more synchronised between species than in reproduction. Distinct periodicity in the reproductive phases between A. adenophora and the associated species was observed, with A. adenophora flowering earlier than most of the other species in all habitats. The reproductive cycle of A. adenophora was over before the onset of rainy season which enabled dispersed seeds to optimize the growing condition provided by the rain, giving head start over associated species. Senescence phases in A. adenophora was longest compared to associated species. The observation made in the study may assist in understanding the phenological behavior of A. adenophora and associated species, and may develop a guideline for future mechanistic management of A. adenophora.
Soil organic carbon (SOC) and total nitrogen (TN) stock are key indicators of soil quality in tropical regions; however, their status is often degraded, especially due to massive deforestation in natural forest areas associated with extensive agricultural land use. The aim of this study was to investigate the dynamics of SOC and TN stock in different land-use systems in the Abobo woreda, Western Ethiopia. To analyze their status, 80 disturbed (composite) and 45 undisturbed soil samples were collected from the top 20 cm of soil in five major land-use types: natural forestlands, grasslands, recently developed commercial farmlands, old commercial farmlands, and small-scale cultivated lands. The results showed that SOC stock varied significantly across the different land-use types, with mean stock ranging from 32.23 Mg·ha−1 in recently developed commercial farmlands to 54.54 Mg·ha−1 in natural forestlands. The mean TN stock ranged from 2.54 Mg·ha−1 in recently developed commercial farmlands to 4.63 Mg·ha−1 in natural forestlands. With natural forestlands as a baseline and the duration ranging in age from 15 to 45 years since land-use conversion, the mean annual absolute rates of change in SOC and TN stock loss were 0.49, 1.49, 0.39, and 0.45 Mg·ha−1·yr−1 and 0.05, 0.14, 0.03, and 0.04 Mg·ha−1·yr−1 for grasslands, recently developed commercial farmlands, old commercial farmlands, and small-scale cultivated lands, respectively. The results of this study revealed that soil disturbance during forestland conversion to tillage enhanced the decomposition rate of organic matter in recently developed commercial farmlands. Nevertheless, after agricultural abandonment and vegetation restoration, the SOC and TN stock capacities were enriched in the old commercial farmlands. It is, therefore, important to effectively restore vegetation and implement sustainable land-use management practices.
This study was conducted in a temperate mixed oak–pine forest of Central Himalaya, India to (i) evaluate altitudinal and seasonal variations in the microbial biomass carbon (C), nitrogen (N) and phosphorus (P) and (ii) analyse the relationships between soil microbial biomass C, N and P and physico-chemical properties of soil. Three permanent plots were established in natural forest stands along an altitudinal gradient, three replicates were collected seasonally from each site, and microbial biomass (C, N and P) were determined by a fumigation extraction method. Microbial biomass C, N and P decreased significantly (p < 0.01, correlation coefficient 0.985, 0.963, 0.948, respectively) with increasing altitude having maximum values during rainy season and minimum values during winter season. Microbial biomass C, N and P showed positive correlations with silt particles, water holding capacity, bulk density, soil moisture, organic C, total N and P and negative correlations with sand particles, porosity and soil pH. Microbial biomass C was strongly associated with soil microbial N (r = 0.80, p < 0.01) and P (r = 0.89, p < 0.01) content and soil microbial biomass N and P also showed a strong linear relationship (r = 0.92, p < 0.01). Soil microbial biomass exhibited weak seasonality and was highly influenced by altitude and abiotic variables. The significantly high microbial C, N and P during the rainy season (p < 0.01) and low microbial biomass during the winter season may be 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. The microbial C:N ratio indicated that soil fertility is influenced by species composition. Our findings suggested that high microbial biomass and low C:N ratios during the rainy season could be considered a nutrient conservation strategy of temperate mixed oak–pine forest ecosystems.
The belowground systems of trees have a major role in forest functioning through absorption of water and nutrient cycling. This study deals with the fine root dynamics including fine root biomass, necromass, production, turnover, and nutrient return in transitional Sal (Shorea robusta Gaertn. f.) dominated sub-tropical forest ecosystems of Central Himalaya, India. Four sites namely,
Site-1 (Kaladhungi), Site-2 (Fatehpur), Site-3 (Ranibagh), Site-4 (Amritpur) were selected in Sal forest within an elevational range between 405 and 580 m above sea level. The dominant and associated co-dominant species were selected from each site for the estimation of fine root dynamics by using sequential core and ingrowth core methods. The results revealed that the fine root biomass, necromass, and production were significantly (p < 0.05)
affected by location, seasons, and soil properties. The fine root biomass and production decreased with increasing soil depth and also influenced by stand characteristics including tree density and basal area. The rainy season was most productive with maximum fine root biomass (507.37 kg ha−1 ) as well as fine root production (600.26 kg ha−1 season−1 ) in the dominant tree
species S. robusta. Among the associated co-dominant tree species highest fine root biomass (330.48 kg ha−1 ) and fine root production (410.04 kg ha−1 season−1) was reported for Tectona grandis L. during the rainy season, while lowest fine root biomass (126.72 kg ha−1) and fine root production (195.59 kg ha−1 season−1 ) in the Glochidion velutinum Wight tree species
during the winter season. Annual fine root production ranged from 460.26 to 1583.55 kg ha−1 yr −1 , while turnover rate varied from 1.37 to 4.45 yr−1 across all the studied sites. The fine roots added carbon input of 154.38 to 564.20 kg ha−1 yr−1 and nitrogen input of 6.58 to 24.34 kg ha−1 yr−1 to the soil through
annual flux. The study improves our understanding on fine root parameters under the influence of sites, soils and seasonal and spatial variation. The return of nutrients to the soil through fluxes from the roots illustrates the role of fine roots in carbon and nitrogen cycling of the forests and this potential can be
harnessed to assess the long-term carbon and nitrogen pool estimations in forests and to plan and manage the forest ecosystems.
Carbon stock assessment in various ecosystems is vital for monitoring the health of these ecosystems and national accounting for the United Nations convention on climate change. The influence of various anthropogenic drivers on carbon stock in different ecosystems has not been examined comprehensively. This study aims to determine the impact of anthropogenic pressures (lopping, cutting, grazing) on soil physico-chemical properties and carbon stock in four temperate broadleaf forests dominated by different species of oak, viz., Banj oak (Quercus leucotrichophora), Rianj oak (Quercus lanuginosa), Moru oak (Quercus floribunda) and Kharsu oak (Quercus semecarpifolia) along an elevation gradient from 1700–3000 m asl in Gori valley, western Himalaya. Biomass data were collected from 120 quadrats of 10 × 10 m size at three distinct altitudes (4 forest sites × 3 altitudes × 10 quadrats) and analysed for carbon stock, whereas soil samples were randomly collected in triplicate from three depths of each altitude of the forest site and further analysed for their physico-chemical properties. A total of 767 individual trees with a diameter of ≥31 cm were measured at twelve sites and standing biomass was estimated following the growing stock volume equations. Mean carbon stock was highest in Moru oak (396.6 ± 29.5 Mg C ha⁻¹) and lowest in Banj oak forest (189.3 ± 48.6 Mg C ha⁻¹). We also found soil to be the largest pool of forest carbon (43.0–59.7%) followed by aboveground biomass (31.5–45.0%), belowground biomass (8.4–11.7%) and litter (0.4–0.5%). The basal area showed significant effect on altitude and carbon stock, whereas disturbance showed significant (p < 0.05) negative correlation with the total carbon stock. Soil nitrogen exhibited a significant positive correlation (R² = 0.60) with the basal area, indicating that nitrogen enhances tree growth and forest carbon stock. However, anthropogenic disturbance showed a significant negative impact on the basal area, soil nutrients and carbon stock of oak forests. This concludes that forest structure, anthropogenic pressure and soil parameters contribute to the carbon stock of the area. Considering the significance of these overexploited oak forests, it is recommended to conserve the old-growth forest species in the study area, since they have the highest carbon accumulation potential.
Himalayas with diverse topographical and ecological zones sustain diverse agroecosystems. Differences in precipitation regimes, cropping systems, land-use systems and availability of resources significantly affects energy flow within agroecosystems (AGEs) of the region. Thus, the present study was aimed to evaluate the energy use pattern and economic profitability of different sized agroecosystems (small, medium and large) along the altitudinal gradient [very low altitude (VLA), low altitude (LA), mid altitude (MA) and high altitude (HA)] of Central Himalaya, India. The sampling was carried out following random stratified design and total 108 agroecosystems (4 altitudes× 3 sizes × 3 replicates × 3 seasons) were assessed. Data collected on quantities of agricultural inputs and outputs were converted to energy values using standard energetic constants and monetary values on the basis of local market price. Low altitude agroecosystems predominantly support cereal + pulse based cropping systems while, high altitudes favour cash crop cultivation (vegetables). Significant variation (P < 0.05) in total input and output energy was observed seasonally, while differences were insignificant across sizes and altitudes. Irrespective of the sizes and seasons, farmyard manure (organic fertilizer) contributed major share of total energy inputs across all altitudes in the order: HA AGEs (66.7 %) > MA AGEs (66.1 %) > VLA AGEs (62.6 %) > LA AGEs (52.1 %). The share of non-renewable energy inputs (inorganic fertilizers and fuel) declined along altitudinal gradient as: LA (31.1 %) > VLA (26.9 %) > MA (12.5 %) > HA (11.8 %). Seasonally, highest net energy was recorded during rainy season (92286 M J ha−1 yr−1) followed by summer (68906 M J ha−1 yr−1) and winter (18686 M J ha−1 yr−1). The economic yield significantly increased with increasing altitude and was recorded maximum for large sized agroecosystems. Energy use efficiency (EUE) differed distinctly (P < 0.05) across seasons and was recorded maximum during rainy season (8) while, across sizes and altitudes it did not vary significantly. EUE did not reflect any definite pattern along altitudinal gradient [HA AGEs (3.84) > VLA AGEs (3.81) > LA AGEs (3.56) > MA AGEs (3.01)]. Benefit-cost ratios (BCR) differed significantly (P < 0.05) along altitudes and was maximum at VLA AGEs (5.27) however, differences were insignificant across sizes and seasons. From present study, it can be concluded that season and altitude had significant impact on the energetics and economic flow of the agroecosystems while, no marked differences were observed for size classes. High altitude agroecosystems were energetically efficient while, monetary wise very low altitude systems.
Ecosystem succession and biodiversity change associated with grassland fires are crucial for the patterns and dynamics of ecosystem functioning and services. The reactions to fire by different grassland types vary diversely, and are determined by certain species assemblages and environments. However, there are still uncertainties concerning the role of fire in affecting grassland ecosystems and how the effects are sustained. By conducting a bibliometric analysis of related articles indexed in the Web of Science between 1984 and 2020, we firstly described the general trend of these articles over the recent decades (1984–2020). The major research progress in the effects of fire on grassland ecosystems was then systematically summarized based on three levels (individual level, community level, and ecosystem level) with eight topics. We concluded that strong persistence or resistance of adapted individuals facilitated community conversion to a novel environment, which temporally and spatially interacted with ecological factors. The novel habitats could maintain more frequent fires and change an ecosystem structure and functioning. Nonetheless, the transformation of ecosystem states will present more uncertainties on prospective succession trajectories, global carbon storage, and subsequent biodiversity conservation. This review is important to flourish biodiversity, as well as aid conservation policies and strategy making.
Grasslands cover an estimated 31%–43% of the Earth’s land surface, possess an intrinsic conservation value, and offer indispensable ecosystem services. However, grasslands have been extensively managed and exploited, face major threats, including land-use change, climate change, woody encroachment, and biological invasion. The primary tools used to sustainably manage grassland soils include prescribed fire, grazing and mowing, and soil amendments. We present four research highlights describing contemporary, leading-edge grassland research examining the importance of plant, soil, and microbial interactions; the underappreciated role of “biocrusts”; and the use of novel crop systems for climate change mitigation. Our synthesis suggests that to sustainably manage grassland soils, we must (1) consider interactions between different above- and belowground ecosystem components; (2) navigate the complex trade-offs produced by different management actions; (3) develop contextual, case-specific best management practices; (4) and integrate the practices of grassland restoration and the sustainable management of grassland soils.
The rhizosphere is the unique hotspot that is highly influenced by plant roots and characterized by higher microbial activity and nutrient availability. Land uses modify the rhizospheric soil properties through the stimulatory effects of various root exudates and soil nutrients. The present work was aimed to study rhizosphere soil properties under different land use systems at Ballowal Saunkhri watershed in Punjab state, India. For this study, soil samples were collected from three land use systems (horticulture, farm forest and cropland) at four depths, viz. 0–15, 15–30, 30–60 and 60–90 cm during pre-rainy and post-rainy seasons. The results indicated that farm forestry system had significantly higher soil organic carbon (SOC), cation exchange capacity, micronutrient cations (Zn, Fe, Cu, Mn) and microbial properties (total microbial count, microbial biomass carbon, basal soil respiration, dehydrogenase activity, alkaline phosphatase activity and microbial quotient) compared with other land use systems. However, bulk density, available phosphorus, available potassium and metabolic quotient were observed higher under cropland system. The principle component analysis identified that SOC and available potassium were the most contributing and reliable variables for assessing soil quality for different land use systems.
Introduction: In Central Himalaya, anthropogenic activities have led to the widespread replacement of Banj oak(Quercus leucotrichophora) forest by Chir pine (Pinus roxburghii) for decades. This study was conducted to determine how natural Banj oak, Chir pine, and mixed oak-pine forest would differ in soil microbial biomass and soil nutrients.Soil microbial biomass nitrogen (SMBN) and phosphorus (SMBP), soil organic carbon (SOC) total nitrogen (TN), and total phosphorus (TP) in the 0 to 15 cm soil layer were investigated in the Central Himalayan region in the stands of Banj oak, mixed oak-pine, and Chir pine forest.
Results: The SMBN and SMBP were significantly higher in Banj oak and mixed oak-pine forest as compared to Chir pine forest that shows more microbial biomass in oak forests. The ratios of SMBN to TN (SMBN/TN) and SMBP to TP (SMBP/TP) were significantly higher in the Chir pine forest indicating that in this forest, the proportion of microbial biomass N and P of the total soil N and P was more as compared to Banj oak forest. A similar pattern of variation was reported in relation to season across the forests, all with an apparent peak in the rainy season.
Conclusion: These results indicate that low microbial biomass N and P may be one of the reasons to create a nutrient poor site in Chir pine forest. The collection of pine litter by local people also impairs the return of nutrients to the soil and makes it difficult for Banj oak to re-invade areas occupied by Chir pine. This calls for cautions in large-scale conversions of the Banj oak forests to coniferous plantations as a forest management practice on concerns of sustaining soil productivity.
Soil carbon and nitrogen are essential factors for agricultural production and climate
changes. A total of 106 soil samples from three agricultural lands (including two
rice fields and one sugarcane field) and four non-agricultural lands (including two
forest lands, one wasteland and one built-up land) in the Mun River Basin were
collected to determine soil carbon, nitrogen, soil pH, soil particle sizes and explore
the influence of pH and soil texture on soil C and N. The results show that total
organic carbon (TOC) and nitrogen (TON) contents in topsoil (TOC: 2.78 ~ 18.83 g
kg−1; TON: 0.48 ~ 2.05 g kg−1) are much higher than those in deep soil (TOC: 0.35 ~
6.08 g kg−1; TON: <0.99 g kg−1). In topsoil, their contents of forest lands and croplands
(TOC: average 15.37 g kg−1; TON: average 1.29 g kg−1) are higher than those of other
land uses (TOC: average 5.28 g kg−1; TON: average 0.38 g kg−1). The pH values range
from 4.2 to 6.1 in topsoil, and with increase in soil depth, they tend to increase and
then decrease. Soil carbon, nitrogen and the C/N (TC/TN ratio) are negatively
correlated with soil pH, demonstrating that relatively low pH benefits the accumulation
of organic matter. Most soil samples are considered as sandy loam and silt loam from
the percentages of clay, silt and sand. For soil profiles below 50 cm, the TOC and TON
average contents of soil samples which contain more clay and silt are higher than those
of other soil samples.
This study evaluated the impact of predominant land uses on the physico‐chemical and biological properties of soils along an altitudinal gradient in Indian Central Himalaya to enhance the scientific knowledge and identify suitable land use pattern. Soil samples were collected from six predominant agricultural land uses including (i) open cropland (OC), (ii) cropland with multiple tree species (C+mT), (iii) cropland with single tree species (C+sT), (iv) crop near rhizosphere of trees (C+R), (v) Homegardens (HG) and (vi) Agriculturally discarded land (ADL). The physico‐chemical properties showed the significant differences with land use systems and altitude. Soil texture varied from sandy loam to clayey loam with altitude. The minimum bulk density and higher porosity were recorded for HG system while WHC, moisture, pH, C, SCS, N, SNS and P in C+mT system. Soil microbial biomass carbon (16‐397 μgg‐1) and nitrogen (28‐68 μgg‐1) were significantly higher in C+mT and lowest under open cropland. The highest microbial biomass was recorded in the lower altitudinal region of Tarai and lowest was recorded in the higher altitudinal region. Across the seasons, soil microbial biomass was maximum during the rainy and minimum during the winter season. Interestingly, ADL also showed significant contribution in soil microbial biomass carbon and nitrogen and could be used for crop production in future. This study concludes that good soil health, higher amount of microbial biomass and better soil qualities occurred in tree planted soils than open crop lands, mainly attributed to the greater availability of organic matter, litter diversity and fine roots.
Bacteria are the highest abundant microorganisms in the soil. To investigate bacteria community structures, diversity, and functions, contrasting them in four different seasons all the year round with/within two different forest type soils of China. We analyzed soil bacterial community based on 16S rRNA gene sequencing via Illumina HiSeq platform at a temperate deciduous broad-leaved forest (Baotianman, BTM) and a tropical rainforest (Jianfengling, JFL). We obtained 51,137 operational taxonomic units (OTUs) and classified them into 44 phyla and 556 known genera, 18.2% of which had a relative abundance >1%. The composition in each phylum was similar between the two forest sites. Proteobacteria and Acidobacteria were the most abundant phyla in the soil samples between the two forest sites. The Shannon index did not significantly differ among the four seasons at BTM or JFL and was higher at BTM than JFL in each season. The bacteria community at both BTM and JFL showed two significant (P < 0.05) predicted functions related to carbon cycle (anoxygenic photoautotrophy sulfur oxidizing and anoxygenic photoautotrophy) and three significant (P < 0.05) predicted functions related to nitrogen cycle (nitrous denitrificaton, nitrite denitrification, and nitrous oxide denitrification). We provide the basis on how changes in bacterial community composition and diversity leading to differences in carbon and nitrogen cycles at the two forests.
Vegetation coverage is an important parameter for affecting soil erosion and the physical and chemical properties of soil. To analyze the mutual influence between vegetation coverage and soil quality at different slope aspects in a reclaimed dump, fitting analyses were built between the normalized difference vegetation index and soil physical properties at each slope aspect. Twenty six quadrats were sampled in slope-platform alternate mode. Each quadrat was 10 m × 10 m. Vegetation index and soil physical properties were measured and calculated. Through curve fitting analysis, the results showed that soil bulk density has a negative correlation with the vegetation index on shady and half shady slopes, sunny slopes, and half sunny slopes. Soil porosity has a positive correlation with the vegetation index on shady and half shady slopes, sunny slope, and half sunny slope. The soil mass water content has a concave function relationship with the vegetation index on shady and half shady slopes and has a quadratic function relationship with the vegetation index on sunny and half sunny slopes, with the parabola moving upwards. The soil gravel content has a linear relationship with the vegetation index on shady and half shady slopes, and the image has a negative slope with a quadratic function relationship to the vegetation index on sunny slope and half sunny slope, with the parabola moving downwards. Due to differences among hydrothermal conditions, the relationship between vegetation coverage and soil quality indicators at different slope aspects is different; therefore, reasonable improvement of soil quality indicators on sunny and half sunny slopes could help plants to grow. These findings feed into a reference document that sets out how vegetation and soil quality may be improved in mining areas.
The majority of the Earth’s terrestrial carbon is stored in the soil. If anthropogenic warming stimulates the loss of this carbon to the atmosphere, it could drive further planetary warming1, 2, 3, 4. Despite evidence that warming enhances carbon fluxes to and from the soil5, 6, the net global balance between these responses remains uncertain. Here we present a comprehensive analysis of warming-induced changes in soil carbon stocks by assembling data from 49 field experiments located across North America, Europe and Asia. We find that the effects of warming are contingent on the size of the initial soil carbon stock, with considerable losses occurring in high-latitude areas. By extrapolating this empirical relationship to the global scale, we provide estimates of soil carbon sensitivity to warming that may help to constrain Earth system model projections. Our empirical relationship suggests that global soil carbon stocks in the upper soil horizons will fall by 30 ± 30 petagrams of carbon to 203 ± 161 petagrams of carbon under one degree of warming, depending on the rate at which the effects of warming are realized. Under the conservative assumption that the response of soil carbon to warming occurs within a year, a business-as-usual climate scenario would drive the loss of 55 ± 50 petagrams of carbon from the upper soil horizons by 2050. This value is around 12–17 per cent of the expected anthropogenic emissions over this period7, 8. Despite the considerable uncertainty in our estimates, the direction of the global soil carbon response is consistent across all scenarios. This provides strong empirical support for the idea that rising temperatures will stimulate the net loss of soil carbon to the atmosphere, driving a positive land carbon–climate feedback that could accelerate climate change.
Man-made forest fires in the traditionally populated zone (about 800–2000 m altitude) are common in much of the Central Himalaya, and are a major topic of environmental debate. This study based on an analysis of data of the State Forest Department at Uttarakhand on incidence of forest fires shows that these are high-frequency, low-severity surface fires of small size, largely determined by the moisture conditions of the pre-monsoon season (from March to mid-June), and the traditional practices of biomass collection by local people.
Due to the different degrees of controls exerted by biological and geochemical processes, climate changes are suggested to uncouple biogeochemical C, N and P cycles, influencing biomass accumulation, decomposition and storage in terrestrial ecosystems. However, the possible extent of such disruption in grassland ecosystems remains unclear, especially in China’s steppes which have undergone rapid climate changes with increasing drought and warming predicted moving forward in these dryland ecosystems. Here, we assess how soil C-N-P stoichiometry is affected by climatic change along a 3500-km temperate climate transect in Inner Mongolia, China. Our results reveal that the soil from more arid and warmer sites are associated with lower soil organic C, total N and P. The ratios of both soil C:P and N:P decrease, but soil C:N increases with increasing aridity and temperature, indicating the predicted decreases in precipitation and warming for most of the temperate grassland region could lead to a soil C-N-P decoupling that may reduce plant growth and production in arid ecosystems. Soil pH, mainly reflecting long-term climate change in our sites, also contributes to the changing soil C-N-P stoichiometry, indicating the collective influences of climate and soil type on the shape of soil C-N-P balance.
Fire is one of the most destructive threats faced by our forests. Fire is good servant but a bad master. The fire season starts in March/April continues up to June. Wildfires destroy not only flora (tree, herbs, grassland, forbs, etc.) and their diversity but also considerable long term negative impact on fauna including wild endangered species. Repeated fires can convert some shrub-lands to grass and fire exclusion converts some grassland to shrub-land and forest. Fires affect animals mainly through effects on their habitat. The extent of fire effects on animal communities generally depends on the extent of change in habitat structure and species composition caused by fire. Fire can also influence a physico-chemical property of soil including texture, color, bulk density, pH, porosity, organic matter, nutrient availability and soil biota. Drought, disease, insect infestation, overgrazing or a combination of these factors may increase the impact of fire on an individual plant species or communities. Common effects include plant mortality, increase flowering, seed production and numerous communal affects. Fire affected area showed reduction in species diversity both in flora and fauna. In a social context, fire directly affects people, property and infrastructure, thereby directly affecting the health and livelihood of individuals and communities.
The present article describes the biodiversity sustained by oak trees and shrubs, both aboveground and below. They support mammals (e.g., deer, monkeys, rodents, flying squirrel and bears), birds (e.g., jays and woodpeckers); gall-forming and other herbivorous insects, parasites, weevils that depend on oak acorns, and ants that colonize remains of the acorn shells; numerous epiphytes including lichens, bryophytes, ferns, and orchids; semi-parasites that in turn support a variety of birds and fruiting fungi both ectomycorrhizal and nonectomycorrhizal; earthworms, springtails and others. Oaks also provide fodder for livestock, firewood for cooking, tools for agricultural activity and leaves for fertilizing fields. In India, in terms of natural coverage, no other genus matches Quercus.
Grasslands are one of Earth’s major biomes and the native vegetation of up to 40 % of Earth’s terrestrial surface. Grasslands occur on every continent except Antarctica, are ecologically and economically important, and provide critical ecosystem goods and services at local, regional, and global scales.
Grasslands are surprisingly diverse and difficult to define. Although grasses and other grasslike plants are the dominant vegetation in all grasslands, grasslands also include a diverse assemblage of other plant life forms that contribute to their species richness and diversity. Many grasslands also support a diverse animal community, including some of the most species-rich grazing food webs on the planet.
Grasslands allocate a large proportion of their biomass below ground, resulting in large root to shoot ratios. This pattern of biomass allocation coupled with slow decomposition and weathering rates leads to significant accumulations of soil organic matter and often highly fertile soils.
Climate, fire, and grazing are three important drivers that affect the composition, structure, and functioning of grasslands. In addition to the independent effects of these factors, there are many interactions among grazing, fire, and climate that affect ecological patterns and processes in grasslands in ways that may differ from the independent effects of each driver alone.
Grasslands occur under a broad range of climatic conditions, though water is generally limiting for some part of the year in most grasslands. Many grasslands experience periodic droughts and a dormant season based on seasonal dry or cold conditions.
Grasslands are sensitive to climate variability and climate changes. There are well-documented shifts in the distribution of North American grasslands in response to past droughts, and both observational data and experiments suggest that grasslands will be affected by future changes in rainfall and temperature.
Fire is a common occurrence, particularly in more mesic grasslands, due to the large accumulations of dry, highly combustible fine fuel in the form of dead plant material. Fire affects virtually all ecological processes in grasslands, from the physiology of individual plants to the landscape-level patterns, though the effects of fire vary with grassland productivity and the accumulation of detritus.
All grasslands are grazed or have experienced grazing as a selective force at some point in their evolutionary history. The ecological effects of grazing vary with climate and plant productivity, and the associated evolutionary history of grazers in different grasslands.
Grasslands have been heavily exploited by humans, and many temperate grasslands are now among the most threatened ecosystems globally. Widespread cultivation of grasslands was the major land-use change that impacted grasslands historically, while multiple global changes drivers (i.e., altered fire and grazing regimes, woody plant encroachment, elevated CO2, invasive species, fragmentation) contribute to the contemporary loss of grasslands.
Grassland restoration aims to recover the diversity and ecosystem services that grasslands provide. While restored grasslands may attain productivity comparable to native grasslands and sequester carbon for extended periods, they typically support much less diversity than comparable native grasslands. Recovery of soil communities and properties is often very slow.
A soil vegetation study was carried out in the Navegaon National Park (Maharashtra). Six soil profiles were excavated under the three plant communities. Physico-chemical and morphological properties of soils were studied and they are classified accordingly. The soils under the plant community Tectona – Pterocarpus – Buchanania are very deep and dark brown to yellowish brown in colour with abundance of silica and iron concretion. These are moderately drained soils with silty loam to loamy in texture. They are classified as loamy, skeletal, mixed hyperthermic family of Typic Ustorthent and Udic Haplustoll. The soils under the plant community Cleistanthus – Ougeinia – Tectona are shallow to medium in depth and dark yellowish brown to dark reddish brown in colour and silty clay loam in texture. These arer classified as loamy, mixed, hyperthermic and loamy, skeletal, mixed hyperthermic family of Udic Haplustoll and paralithic vertic Haplustoll. The soils under the plant community Cleistanthus – Terminalia – Lagerstroemia are deep silty loam in texture and dark brown in colour, acidic to neutral. These are classified as loamy, mixed, hyperthermic family of Udic Argiustoll and Udic Haplustoll.
Factors such as topography, soil composition, and nutrient availability significantly influence the density patterns of Ageratina adenophora. Understanding these dynamics addresses a gap in our knowledge of the species' adaptive mechanisms in mountainous regions. Furthermore, the impact of habitat features along road corridors on the population dynamics of invasive plants remains underexplored, particularly regarding the effects of disturbance levels, light availability, and soil properties on their establishment. A species-specific rapid ecological assessment was conducted using stratified random sampling, with parallel transects of 50 × 2 m established in triplicates at 20 m intervals. This resulted in 43 main transects across the identified plots and 67 parallel transects in adjacent habitats. The number of individuals of A. adenophora and its clumps were recorded from each quadrat. Chemical and physical parameters of soil were measured for soil collected from 0-15 cm depth. Linear Mixed Model analysis revealed a significant negative effect of elevation (p<0.05) on the density of clumped individuals (Estimate: -0.31, t-value: -3.05), total individuals (Estimate: -0.27, t-value: -2.61), and clump number (Estimate: -0.30, t-value: -4.78). Western aspect also showed a significant decrease in clumped individuals (Estimate: -1.83, t-value: -2.80), total individuals (Estimate: -2.24, t-value: -3.47), and clump number (Estimate: -0.81, t-value: -1.97). Total A. adenophora density was highest near settlements (133 ind. m², Estimate: 1.19) and grasslands (103 ind. m², Estimate: 1.16), but lowest in broadleaf forests (26 ind. m²). Density decreased significantly with increasing distance from road verges (Estimate: -0.24, t-value: -2.34). Soil moisture content positively influenced total individuals (Estimate: 0.19, t-value: 2.75), clumped individuals (Estimate: 0.23, t-value: 3.20), clump numbers (Estimate: 0.05, t-value: 1.09), and individuals per clump (Estimate: 0.37, t-value: 3.28). Available nitrogen positively influenced non-clumped individuals (Estimate: 0.17, t-value: 2.04) but negatively affected individuals per clump (Estimate: -0.25, t-value: -2.21), indicating that lower nitrogen levels correlate with higher individual density per clump. Hence, effective restoration efforts are needed including soil improvement, invasive species removal and control, and the planting of native species.
This study aimed to examine the effects of spatial and temporal variability in edaphic, and climatic attributes on soil net nitrogen mineralization rate, and to understand the pattern of fine root decomposition of dominant and co-dominant tree species, and its influence on the nutrient cycling in forest ecosystems. Study was carried out at four different sites in sub-tropical forest ecosystems of Shorea robusta, in foothills of Central Himalayan region, India. Co-dominant tree species at four sites were Mallotus philippensis (site A), Glochidion velutinum (site B), Holarrhena pubescens (site C), and Tectona grandis (site D). Buried bag technique was used for nitrogen mineralization, while fine root decomposition was determined using fine root mesh bags. Seasonal variation, soil depth, soil characteristics, and site variability, all significantly (p < 0.05) affected nitrogen mineralization rates. Fine root decomposition was significantly affected by nutrient concentration of fine roots. Total mineral nitrogen was maximum at site D (16.24 ± 0.96 μg g−1 soil), while minimum at site C (10.10 ± 0.84 μg g−1 soil). Maximum nitrogen mineralization (13.18 ± 0.18 μg g−1 month−1) was recorded during summer season at site D, while the minimum nitrogen mineralization (3.20 ± 0.46 μg g−1 month−1) was recorded during rainy season at site C. Inorganic-N and net nitrogen mineralization was relatively higher in 0–20 cm soil layer than 20–40 cm and 40–60 cm soil layer. The fine roots showed 70.61–74.82 % weight loss on completion of 365 days of decomposition
process. Maximum fine root decomposition was observed in the G. velutinum, and minimum in T. grandis. A significant positive correlation (p < 0.05) was observed between root nitrogen and carbon content, and decomposition rates per month. This study concluded that the spatial and temporal variability in soil nitrogen mineralization rates and fine root decomposition optimises nutrient cycling in forest ecosystems, which can contribute to the development of sustainable forest management practices.
The present study deals with the understory structure, diversity, and soil macro and micronutrients in vari�ous forest stands of the Duldula forest in northern Chhattisgarh. Forest stands include four natural (dense,
moderately dense, regenerated, and degraded forests) and one plantation (teak). Stratified random sampling
methods were used to evaluate the phytosociological attributes of shrubs, climbers, and herbs in various for�est stands. Soil samples were analyzed for macro and micronutrients at two different depths (0�10 cm and
10�20 cm). A total of 14 shrubs, 17 climbers, and 30 herb species representing 9, 8, and 12 families, respec�tively were recorded from various forest stands. The total density value of shrubs, climbers, and herbs ranged
between 600 and 1760 individuals ha�1
, 320�5240 individuals ha�1, and 356,000�684,000 individuals ha�1
,
respectively for different forest stands. Shannon index values for shrub, climber, and herb ranged between
0.78�2.88, 1.68�2.45, and 2.57�3.59, respectively. The soil of the study area was found to be acidic in nature
with moderate levels of organic carbon (%), macro, and micronutrient status. Considering the total density
value of various forests stands highest number of shrubs, climbers, and herbs were recorded in degraded for�ests which indicates the process of degradation facilitates the growth of understory vegetation in comparison
to tree species. In most cases, the soil attributes were higher in dense forests. This, therefore, indicates that
sustainable management of the soil is essential for the restoration of degraded forests to a natural condition.
Invasive plant Ageratina adenophora
(Sprengel) R. King & H. Robinson has invaded
majority of the temperate forests in Kumaun, Central
Himalaya. Information on A. adenophora invaded
forest types, their structural attributes, population
demography and regeneration status are still at
rudimentary level. Considering this, the present study
was conducted to assess the impacts of A.
adenophora on vegetational attributes and
regeneration status of three forest types, viz., Oak
(Quercus oblongata D. Don), Pine (Pinus roxburghii
Sarg.) and Cypress (Cupressus torulosa D. Don). We
selected three sites for each forest type and each site
was further purposively stratified into paired
sampling plots of 1 ha each i.e., A. adenophora
invaded and uninvaded sites. Our results showed
large densities of cut stumps or felled trees
throughout invaded sites, but with fewer fire signs in
comparison to uninvaded sites. In uninvaded sites,
total density and basal area calculated for woody
species were relatively higher than those in invaded
sites, although results were insignificant (p>0.05).
With the exception for Cypress forests, vegetation
indices showed low woody species richness and
diversity in invaded Oak and Pine forests. Also,
regeneration of Q. oblongata, P. roxburghii and C.
torulosa tree species did not differ significantly
(p>0.05) between invaded and uninvaded sites. These
insignificant differences clearly imply that A.
adenophora’s presence has not entirely changed the
perennial plant communities in terms of composition,
structure and natural regeneration. However, tree
species with poor or no regeneration status requires
special attention and needs management strategies
involving control of invasive species in forest
ecosystems.
A floristic and structural survey of a natural temperate grassland community was conducted in the Nainital district of Kumaun Himalaya, India, to examine the effect of slope aspect as one of the topographical factors on the vegetation composition and soil characteristics. Structural data was collected by sampling the vegetation from three slope aspects viz. North aspect (NA), East aspect (EA) and South aspect (SA). Three permanent plots of 20 m × 20 m were established at each aspect and within each of these plots 10 quadrats of 1 m × 1 m were placed randomly, and various ecological parameters were determined. Soil samples were collected from 2 depths i.e. 0–15 cm (surface layer) and 15–30 cm (subsurface layer) and soil characteristics were determined. A total of 22 species were recorded out of which NA had 16 species belonging to 8 families, EA had 14 species belonging to 9 families and SA had 7 species belonging to 5 families. Density, total basal area, diversity, evenness, and biomass showed significant effects of slope aspect. Significant positive relationships between ecological parameters (density, total basal area, diversity, species richness, and biomass) with soil characteristics (moisture, temperature and water holding capacity) suggested strong influence of edaphic variables on ecological parameters. NA contained more moisture, had a higher water holding capacity and lower soil temperature as compared to SA which encourages the herbaceous vegetation and facilitates the growth of species.
Soil physical and chemical properties and microbial biomass dynamics are significantly related to vegetation types. However, how different vegetation types influence the soil and microbial dynamics remains poorly understood. The aim of the present study is to assess the influence of vegetation types on soil physical properties (bulk density (BD), porosity, moisture, texture, and water holding capacity), chemical properties (soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), soil pH and electrical conductivity (EC), and SOC, TN and TP stocks), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), microbial biomass phosphorus (MBP), and stocks as well as soil and microbial biomass C: N: P stoichiometry within three soil depth (0–10 cm, 10–30 cm and 30–60 cm) in central Himalaya. Five vegetation types, namely oak (Quercus leucotrichophora A. Camus) forest, Chir-pine (Pinus roxburghii Sarg.) forest, deodar (Cedrus deodara (Roxb.) G.Don) forest, Sal (Shorea robusta (Roth) forest) and one was abandoned agricultural land was selected for the present study. Principal component analysis (PCA) and correlation analyses were performed to evaluate the relationship among physical, chemical, and microbial characteristics and stoichiometry. ANOVA revealed significant differences in soil physical and chemical properties, microbial biomass, and stoichiometry due to vegetation types (P < 0.001), soil depths (P < 0.001), and vegetation types × soil depth interaction (P < 0.001). The results showed that the SOC, TN, TP, MBC, MBN, and MBP contents decreased with soil depths. MBC, MBN, and MBP contents were significantly and positively related to SOC, TN, and TP contents. Oak and deodar forests had the highest, SOC, TN, TP, MBC, MBN, and MBP contents, compared with other vegetation types. Sal forest soil (0–10 cm) had the highest SOC: TN, and SOC: TP ratios. Different vegetation types have different soil properties and stoichiometry, implying their different soil C, N, and P stocks. Thus our findings can help in developing a promising guideline for sustainable management strategies and soil management in long run.
This study estimated seasonal variations among several parameters of the fine roots
and N dynamics in Mangifera indica based agroforestry systems e.g., homegarden
(HG), agri-horticulture (AH) and agri-horti-silviculture (AHS) systems in bhabhar
region of Indian Central Himalaya. Fine root biomass (FRB) and fine root
production (FRP) of M. indica were highest in AH system and lowest in HG system
while fine root turnover (FRT) showed a reverse trend. FRB, FRP and FRT rate
decreased with soil depth and distance from the tree base, with larger variations in
AH system. The biomass: necromass ratio varied between 1.91 and 2.42 for HG,
between 2.27 and 3.29 for AH and between 2.09 and 2.46 for AHS systems. Among
all the selected agroforestry systems, concentrations of mineral N (NH4-N and NO3-
N) were higher in AH system and lower in AHS system while net N mineralization
rates were higher in AHS system. In HGs, FRB was significantly correlated with
ammonification, nitrification and N mineralization while, in AH system it was
positively correlated with nitrification and N mineralization. In AHS system it was
positively correlated with ammonification only. Thus it can be concluded that in
agroforestry systems FRB was enhanced by rapid N mineralization. The variability
in FRB and N mineralization between selected agroforestry systems were possibly
due to the differences in soil characteristics and management practices. For
enrichment of soil nutrients, the contribution of fine roots could be of more
importance through the process of decomposition under the prevailing agroforestry
systems.
The tropical deforestation due to biotic interference, land use change, and population explosion in Asian countries has attracted the global concern with respect to conservation and protection of forest resources. Indian soils are limited in terms of nutrient reserves and organic matters. Our present study deals the influence of disturbance on phytosociology, vegetation carbon (C), and nitrogen (N) along with soil properties of tropical deciduous forest in Chhattisgarh. The stratified random sampling technique was used for quantifying the vegetation. Results revealed that 43.75% species are rare in occurrence in undisturbed forest (UF), and in disturbed forest (DF) about 50% species showed rarity over the area as per the Raunkiaer frequency class of species rarity and commonness. Total density and basal cover were 1090 trees ha−1 and 28.16 m2 ha−1, respectively. in UF and was 190 trees ha−1 and 10.99 m2 ha−1 in DF. The disturbance resulted into 31.63% loss in total biomass in DF compared to UF. The increasing disturbances are altering the forests attributes in terms of poor standing stock, basal area, and diversity in DF. The concentration of dominance and beta diversity value was higher in DF. It may be increased due to influx of generalist species in DF. Stand biomass was found to be 3‐times higher in UF than the DF. Higher value of C and N stock and soil nutrient were found in UF. Thus, proper conservation, protection, and restoration of these forests should be the priority to improve the C pool and ecological services.
Clarifying the response of soil microbial communities and their potential functions during succession is of great significance for understanding the biogeochemical processes and the sustainability of forest development. However, the study of microbial community dynamics during the process of succession remains poorly understood in boreal forest ecosystems. Thus, in order to study the dynamics of microbial diversity caused by succession, we adopted the "space instead of time" method and selected four habitats in a national natural reserve (including grassland, birch forest, mixed forest and larch forest) to represent the primary successional sequence of the boreal forest. We used 16S and ITS rRNA gene sequencing to detect bacterial and fungal communities and used FAPROTAX and FUNGuild database to predict bacterial and fungal functional groups. The results showed that forest succession significantly changed the community composition of bacteria and fungi, among which the fungal community was more sensitive to the changes with successional stage. The relative abundance of ectomycorrhizal fungi significantly increased with succession, while the relative abundance of bacterial functional groups involved in the nitrogen cycle did not change significantly, indicating that fungi might play a major regulatory role in the nutrient cycling process during the successional process. In this study, the soil total carbon and total nitrogen were the dominating factors affecting the soil microbial community and the structure of fungal functional groups. Our results suggest that the shifts in fungal community structure and functional groups may play a key role in soil nutrient cycling during boreal ecosystems succession.
The conversion of natural forest to artificial vegetation may deplete nutrients and thus affect the soil quality. However, little is known about synergetic changes of microbial and physicochemical dynamics in soils after natural forest conversion and their implications. In the current study, we synthesized the responses of soil microbial and physicochemical properties in the uppermost soil layer (<20 cm) following natural forest conversion, as reported in 51 published studies (127 sites). Our results showed that the response ratios of soil moisture, soil microbial carbon and nitrogen, bacteria, fungi, enzymatic activities, soil organic carbon, total carbon, total nitrogen, NO3–, total phosphorus, available phosphorus, cations (K⁺, Mg²⁺ and Ca²⁺), and cation exchange capacity (CEC) overall declined following natural forest replacement. In contrast, natural forest conversion caused significant increases in soil bulk density, soil pH and NH4⁺. Reductions of microbial carbon, organic carbon and total nitrogen in soil were independent of revegetation type, but variations in soil pH, available phosphorus and fungi were correlated to land use. Soil CEC reduction increased soil pH, allowing soils to retain NH4⁺, which promoted fungal growth. Moreover, natural forest replacement led to the loss of soil cations in regions of higher precipitation. Revegetation practices led to greater consumption of soil microbial and chemical nutrients and produced “harder” soils (increased soil compaction and decreased moisture content) in warmer regions. Stand age influenced ratios of soil carbon to nitrogen and ratios of bacteria to fungi following natural forest conversion. Altogether, our study suggests that natural forest conversion results in decreased soil microbial and chemical fertility, and desirable soil properties are more likely to be lost in warmer regions and over time as global climate warming exacerbates, which in turn may potentially damage ecosystem sustainability.
Excessive land use has a series consequences on the degradation of land function and exerts tremendous pressure on the ecological environment. Farming, mining, and heavy metal pollution have resulted in many negative effects on soils. Biochar has become a hot research topic in the fields of agriculture, environment, and energy as an environmentally friendly soil improver in recent years. The application of biochar for both agricultural and environmental benefits has been studied and reviewed extensively. However, there are limited reviews on the structures of biochar and other biochar applications. This paper provides an overview of recent advances in the effects of the various physicochemical properties of biochar and biochar utilizations including its use as catalyst, soil amendment, water retention, contaminant adsorbent, gas storage, ion exchange, and soil microbial activity. Discussions on biochar on the physical, chemical, biological properties after amendment to the soil and preparation condition. However, the negative effects of biochar in preparations and applications need to be recognized through scientific observation and research. It is anticipated that further research on biochar amendment will increase the understanding on the interactions of biochar with soils, review the negative effects of biochar and it should be alleviated as much as possible.
Forest fire monitoring, assessment, and management are important aspects of the tropics because of their significant ecological, economic, and social impact. Soil is considered one of the most important natural resources. Wildfire alters the soil nutrient status and pool through volatilization, erosion, leaching, oxidation, and ash transport. Little information is available on how soil properties, carbon stock, nitrogen stock, and soil microbial biomass carbon vary along depth and fire severity (high, medium, low, and no fire). In order to address this question, soil was sampled from 0–10 to 10–20 cm depths from different fire zones (high, medium, low, and no fire zone) of Bhoramdeo Wildlife Sanctuary of Chhattisgarh, India. The level of macronutrients, carbon stock, nitrogen stock, and microbial biomass carbon was higher at no-fire zone than in the rest of the sites (high, medium, and low severity fire zones). Total soil carbon stock (0–20 cm soil depth) was highest in no-fire zone (69.51 ton ha−1) followed by medium (66.55 ton ha−1) or low fire severity (53.69 ton ha−1). The total soil nitrogen stock across the sites ranged between 2.60 and 4.08 ton ha−1, and it was higher in the no-fire zone followed by the medium or high fire severity. Soil microbial biomass carbon reflected a similar trend with higher values in no-fire zone followed by the medium fire severity, high fire severity and low fire severity zones. Such information on wildfire and soil attributes is essential for the preparation of better management and action plan to regulate the forest soil quality.
The main objective of the study was to investigate influence of Nepalese alder (Alnus nepalensis D. Don) on fine root biomass (diameter ≤ 2 mm) dynamics and the physical and chemical properties of the soil in white oak (Quercus leucotrichophora A. Camus) forests. Five representative stands of each oak mixed alder (OMA) and oak without alder (OWA) were selected along the stand development gradient in the Indian central Himalaya. Fine root and soil samples from of 0–10 cm, 10–20 cm, and 20–30 cm depths were collected using soil core method. Soil physical and chemical properties and monthly variations in fine root dynamics (biomass distribution and decomposition) were analyzed. Fine root decomposition was studied by using the litterbag technique. Redundancy and correlation analyses were performed to evaluate the relationship between fine root dynamics, stands, and tree total basal area and soil properties. Both the fine root biomass and production of Q. leucotrichophora were significantly (P < 0.05) higher for oak without alder stands than oak mixed alder stands. Fine root biomass, production, and turnover rate of A. nepalensis were significantly (P < 0.05) higher than Q. leucotrichophora in oak mixed alder stands. Within the investigated soil profile, in all the sites, maximum fine root biomass and production were found in the upper (0–10 cm) soil depths. The analyses revealed clear differences in all the measured soil physical and chemical properties and fine root traits in oak mixed alder and oak without alder stands. The soil organic carbon (SOC), total nitrogen (TN) contents, and soil C and N stocks were significantly (P < 0.05) higher in oak mixed alder stands than oak without alder stands while opposite trends were found for soil pH and bulk density (BD). Present findings reveal that improvement of the soil properties under oak mixed alder stands was significantly higher than the oak without alder stands. Fine root decomposition for A. nepalensis was significantly faster than Q. leucotrichophora. Q. leucotrichophora fine roots in OMA stands decomposed at significantly faster rates compared to OWA stands. Additionally, the present study suggests that variation, in fine root dynamics across the forest stands was not only positively correlated to the soil physical and chemical properties but also highly dependent on the forest stand characteristics.
The effect of living roots on the co-mineralization of soil organic carbon (SOC) and nitrogen (SON) and driving mechanisms of the rhizosphere priming effect (RPE) remains unclear. Moreover, it is still poorly understood whether the abiotic mechanisms, whereby roots accelerate soil organic matter (SOM) loss by destabilizing organo-mineral associations, are involved. Biotic and abiotic processes involved in the RPE and gross N mineralization (GNM) were investigated using three paddy soils (C 3) under maize (C 4 plant) cultivation. The soils had high and low total N (1.79 and 3.3 g kg − 1 soil) as well as iron-(Fe-) (hydr-) oxide (1.1 and 2.2 g kg − 1 soil) contents, which gave the following combinations: high-Fe/low-N, low-Fe/low-N, and low-Fe/high-N. The RPEs and GNM were measured using a 13 C-natural abundance approach and 15 N-pool dilution technique, respectively, on day 86 of maize cultivation. Living roots enhanced native SOC mineralization by 70.4-204% and GNM by 118-382%. As expected, biotic mechanisms contributed to RPEs ('microbial activation' and 'microbial N-min-ing') that was supported by the increase of soil microbial biomass C and extracellular enzyme activities in presence of plant, and the lower C/N ratio of primed SOM than the original SOM in unplanted soils. Higher RPEs and relative primed N mineralization via stronger 'microbial N-mining' were found in low-Fe/low-N vs low-Fe/ high-N soils. In contrast to expectations, the RPEs and relative primed N mineralization were greater in high-Fe/ low-N versus low-Fe oxide soils. The strongest decrease in SOM-derived Fe-bound C and increase in root-derived Fe-bound C were observed in the high-Fe soil, because root exudates liberated more C from Fe-bound SOM and co-precipitated with Fe oxides. This shows that the abiotic process was involved in RPEs whereby root exudates promoted soil C loss by releasing it from Fe-organic complexes. Thus, this study demonstrated that coupled biotic-abiotic processes could regulate RPEs.
Soil organic carbon (OC) and nitrogen (N) dynamics following afforestation are crucial for evaluating the balance of OC and N and their feedback to ecosystem functionality. However, the variations in newly input and old OC and N among soil aggregates are rarely studied. This knowledge gap hinders our understanding of the mechanisms behind OC and N responses to land-use changes. Herein, we measured the natural abundance of δ¹³C and δ¹⁵N and soil OC and N stocks in bulk soils and aggregates (>0.25 mm, 0.25–0.053 mm and <0.053 mm) in afforested land to identify the dynamics of newly input and old OC and N after land-use change. Soils were collected from farmlands (age 0) and afforested woodlands ranging in age from 10 to 35 years in China’s Loess Plateau. We showed that afforestation decreased the natural abundance of δ¹³C and δ¹⁵N in bulk soils and aggregates, and δ¹³C and δ¹⁵N were mostly enriched in the silt + clay fraction. Afforestation resulted in an increase in total and newly input OC and N; however, the old OC and N remained stable in the bulk soils and macroaggregates. Increases in new OC and N were the main contributors to the accumulation of soil OC and N pools in the topsoil. Furthermore, the OC and N associated with macroaggregates accounted for 76.5–84.0% and 42.2–83.5% of the new OC and N in bulk soils, and 52.7–79.7% and 64.3–86.6% of the old OC and N in bulk soils along the 10–35 years afforestation. The coupling effects of OC and N existed in new- and old- OC and N stocks, regardless of bulk soils or aggregates. These results indicated that both macroaggregates and newly input OC and N contributed to the synchronous sequestration of OC and N in soils after afforestation.
Large-scale primary native broadleaf forests (BF) have been converted to secondary forests (SF) and plantation forests (PF) in subtropical China over the past decades. However, how and what magnitude of plant and soil carbon (C), nitrogen (N), and phosphorus (P) stocks and stoichiometry are affected by forest conversion is still vague. Here, we addressed this issue by systematically measuring tree biomass and the C, N, and P concentrations in tree organs and soils (0–100 cm) collected from 300 plots in Fujian province. With forest conversion of BF to PF, the tree C, N, and P stocks declined by 43.8, 47.9, and 63.1%, respectively, and the soil C and N stocks across whole soil depth decreased by 19.1% and 13.0%, respectively, and these decreases were more evident after conversion of BF to PF than SF. However, soil P stock showed a tendency of decreasing at 0–20 cm soil depth but increasing at 20–100 cm soil depth following conversion of BF to SF and PF. This unconformity of the vertical pattern of P stock in contrast to C and N stocks, was perhaps due to higher C and N inputs and greater P uptake from the subsoil and its redistribution to the topsoil in BF than in SF and PF. The tree and soil C, N, and P stoichiometry was strongly related to tree biomass, indicating that tree biomass was a vital factor driving soil inputs and retention of nutrients, and thus affecting their stoichiometry. The leaf N:P ratios ranging from 16.7 to 17.2 at our study sites suggested that co-limitations of N and P for forest growth could occur in the studied region. Our results provided insights into the C, N, and P linkages between soils and trees as affected by forest conversion, and advised that predicting these linkages could be an effective approach to identify the impacts of forest conversion, thereby implementing targeted conservation and rehabilitation actions.
China initiated the “Grain for Green Project” in 1999 to mitigate soil erosion. The vegetation cover of the Chinese Loess Plateau, one of the most erosive regions in the world, has been greatly increased. However, studies on quantitatively investigating the climate change and human activities on vegetation coverage change were rare. In this study, spatio-temporal changes in vegetation coverage were investigated using MODIS normalized difference vegetation index (NDVI) data over 2000–2016. And a new method was introduced using Net Primary Productivity (NPP) model and relationship between NPP and NDVI to quantitatively and spatially distinguish the NDVI affected by climate change and human activities. Results showed that mean NDVI value over 2009–2016 were 14.46% greater than that over 2000–2007. In order to quantify the contribution of climate change and human activities to vegetation change, an NPP model suitable for the grassland of the Chinese Loess Plateau was identified using biomass observations from field survey and literature. The NDVI affected by climate change (NDVIclimate) was estimated by the NPP model and the relationship between NPP and NDVI. And the NDVI affected by human activities (NDVIhuman) was calculated by actual NDVI minus NDVIclimate. Comparison of the two stages showed that human activities and climate change contributed 42.35% and 57.65% respectively to the ΔNDVI on grassland in the Loess Plateau. After analysis of numerous NDVIhuman related factors, the slopes restored by the “Grain for Green Project” was considered the main influence factor of human activities.
Organic carbon (OC) and nutrient dynamics are closely related to soil texture, but how texture influences the distribution of OC and nutrients in aggregates in various land use types has not been examined. This knowledge gap precludes our mechanistic understanding of soil biogeochemical cycles at large spatial scales. Herein we compared the contents and stoichiometric ratios of OC and nutrients in both bulk soils and aggregates in cropland and woodland across a clay content gradient (7–31%) in the Loess Plateau. The soil metrics that were measured included the proportions of water-stable aggregates, and the contents of OC, nitrogen (N) and phosphorous (P) in bulk soils and each aggregate fraction. The stoichiometric ratios of carbon (C), N and P were calculated. The relationships between soil metrics and clay content were analyzed. We hypothesize that OC, N and P in aggregates increase with clay content, and these relationships are independent of land use types. In partial support of these hypotheses, the proportion of macroaggregates and the contents of OC, N and P in bulk soils and most aggregate fractions linearly increased with clay content. The slopes of these linear relationships were not affected by land use type. The C/N ratio were minimally affected, while the C/P and N/P ratios in both bulk soils and aggregates increased with clay content, and these relationships changed with land use type. Proportion of macroaggregates, contents of OC and N, and ratios of C/N, C/P and N/P were significantly higher in woodland than in cropland across or within sites. Furthermore, the distribution patterns of OC, N and P contents, and C/P and N/P ratios among aggregates varied with site and land use type. These suggested that soil texture determines the distribution of OC, N and P and their stoichiometric ratios within soil aggregates in the Loess Plateau of China, and most of these determining relationships were independent from land use types.
Understanding the influences of land use conversions on soil quality (SQ) and function are essential to adopt proper agricultural management practices for a specific region. The primary objective of this study was to develop soil quality indices (SQIs) to assess the short-term influences of different land uses on SQ in semiarid alkaline grassland in northeastern China. Land use treatments were corn cropland (Corn), alfalfa perennial forage (Alfalfa), monoculture Lyemus chinensis grassland (MG) and successional regrowth grassland (SRG), which were applied for five years. Twenty-two soil indicators were determined at 0-20cm depth as the potential SQ indicators. Of these, thirteen indicators exhibited treatment differences and were identified as the total data set (TDS) for subsequent analysis. Principal component analysis was used with the TDS to select the minimum data set (MDS), and four SQIs were calculated using linear/non-linear scoring functions and additive/weighted additive methods. Invertase, N:P ratio, water-extractable organic carbon and labile carbon were identified as the MDS. The four SQIs performed well, with significant positive correlations (P<0.001, n=16) among them. However, the SQI calculated using the non-linear weighted additive integration (SQI-NLWA) had the best discrimination under different land-use treatments due to the higher F values and larger coefficient of variance as compared to the other SQIs. The SQI value under the MG treatment was the highest, followed by that under the SRG and Alfalfa treatments, and all of these were significantly higher than that of Corn treatment. These results indicated that conversion of cropland to perennial forage or grassland can significantly improve the SQ in the Songnen grassland. In addition, SQI-NLWA can provide a better practical, quantitative tool for assessing SQ and is recommended for soil quality evaluation under different land uses in semiarid agroecosystems.
Litter decomposition in terrestrial ecosystems has a major role in the biogeochemical cycling of elements in the environment. Climatic features, like temperature, rainfall, humidity, and seasonal variations affect the rate of litter decomposition. This review attempts to understand the litter decomposition process in tropical forest ecosystems. It also reviews the influence of various factors on litter degradation and techniques used for assessing leaf litter decomposition. It is observed that very few studies were conducted on litter decomposition in forest ecosystems, such as tropical and temperate forests. Hence, comprehensive studies on litter degradation have to be undertaken in order to understand the turnover rate of nutrients and other elements in these sensitive ecosystems.
Grazing management is a known influence of carbon accumulation in agricultural soil, but there is conflicting evidence on the extent. This study compared organic carbon and nitrogen stocks at the conclusion of a 5-year grazing trial on a fertilised native pasture in south-eastern Australia. The study included three grazing treatments: ungrazed, tactically grazed (set stocking with biannual rest periods) and cell grazed (intense stocking with frequent long rest periods). There was no influence of grazing treatment detected on pasture sward composition when averaged over seasons or on total nitrogen or bulk density. The cell grazing treatment had total carbon stock of 32·9MgCha-1 (SE=1·8) in the 0-0·30m soil layer, which was a significant increase (p<0·05) relative to the ungrazed treatment at 25·6MgCha-1 but not statistically greater than the tactical treatment at 29·5MgCha-1. There was no difference detected in labile carbon stocks to 0·30m, which indicates that differences in soil carbon due to grazing was accumulated over the 5-year trial rather than reflecting short-term seasonal impacts. We propose that a combination of factors contributed to a greater stock of soil carbon under grazed pastures including differences in plant shoot/root allocation, root growth and root turnover with defoliation under grazing as well as lower plant productivity where grazing is excluded because of shading and nutrient tie-up. This study demonstrates removing grazing pressure may lead to lower soil carbon stocks in native pastures over time and provides evidence of the potential for grazing management to increase soil carbon in the short-term.
Evergreen broad-leaved forest (EBLF), covering a lot of area in China, is the zonal vegetation type in subtropical area. However, under long-term human disturbances, this forest is shifting to include much more degraded area dominated by secondary forests, shrub and grassland. Unfortunately, forest nutrients dynamics remain poorly qualified, despite the growing view that these processes might be extremely important in helping us understand changes of biogeochemical cycle in the context of the global change (particular in the change of land use), and shedding light on the conservation and restoration of EBLF. To understand the impacts of the degradation of EBLF on soil carbon and nutrient pools, we chose mature EBLF as the reference climax forest, and secondary and young evergreen broad-leaved forest, secondary conifer and evergreen broad- leaved mixed forest, secondary coniferous forest, shrubs and grassland to represent different degradation stages in Tiantong National Forest Park. After examining soil nutrients and carbon pools, we obtained the following results and conclusions: (1) Soil total N stocks displayed the following order: mature evergreen broad-leaved forest > secondary and young broad- leaved forest > shrub > secondary coniferous forest > grassland > secondary conifer and broad-leaved mixed forest; (2) soil total P is in the order: mature evergreen broad forest > secondary coniferous forest > secondary conifer and broad- leaved mixed forest > secondary and young broad-leaved forest > grassland > shrub; (3) soil organic carbon is in the pattern of mature evergreen broad forest > secondary coniferous forest > secondary and young broad-leaved forest > shrub > grassland > secondary conifer and broad-leaved mixed forest; (4) stock of soil NH4+-N displayed an "U" shape in the series of EBLF degradation; and (5) stock of soil NO3- was highest in the grassland than other degraded types, in which significant differences were not found. These results suggested that soil carbon and nutrients pools decreased gradually during degradation of EBLF. The mature EBLF can be considered as a major carbon sink and a huge nutrient pools in this region.
Soil chemical properties under grassland were compared with those under adjoining first-rotation pine forest aged 20 and 25 years, at coastal and inland hill country sites in Canterbury, New Zealand. The pasture sites had been treated with fertiliser but not limed. Organic carbon, total nitrogen, sulphur, and phosphorus, and exchangeable potassium, calcium, and magnesium levels were lower in soil beneath forest at one or both of the sites. In contrast, available phosphorus and sulphur concentrations were marginally higher beneath forest at both sites despite fertiliser application to grassland. Mineralisable nitrogen also was higher beneath forest at the inland site, but not at the more agriculturally developed coastal site. Differences between sites for total sulphur and exchangeable magnesium were ascribed to greater atmospheric inputs of these elements to forest at the coastal site. At both sites, soils under forest were more acid and had higher exchangeable aluminum levels. Differences between forest and grassland for organic carbon and total nitrogen and phosphorus were confined to the upper soil layers (0-0.1 m), while differences in soil acidity progressed to a depth of 0.2 m, and differences in exchangeable cations were evident to 0.4 m, the greatest depth measured. Soil (< 2 mm) bulk density and nutrient pools were measured at the coastal site, and bulk density was similar beneath forest and grassland. Total nitrogen and exchangeable potassium and magnesium pools to 0.3 m depth were lower under forest than grassland, while the exchangeable aluminium pool was higher under forest. Organic carbon, total phosphorus and sulphur, and exchangeable calcium pools were similar under the two types of vegetation. Lower concentrations and pools of nutrients in soil beneath forest may have been due to uptake and sequestration of nutrients in forest biomass, or to fertiliser application to grassland, although the latter would have been counteracted to some extent by nutrient removals by grazing animals.
Leases of land concessions in Cambodia have accelerated in the last ten years. An analysis using high-resolution maps and official documents shows that deforestation rates in the land concessions are higher than in other areas.
African tropical forests are thought to play an important role in global carbon sequestration. However, the
increasing rate of deforestation and the impact of changes in land use require a critical and updated look at
what is happening. This work emphasizes the role of bulk density as a main driver in carbon (C) and nitrogen
(N) stock in four land-use categories: natural forest, tree plantations, crop land and degraded soil. The study
was conducted in the Central Highlands of Ethiopia, where deforestation and human pressure on native forests are exacerbated and erosion has caused extensive soil loss. The methodological approach consisted of evaluating the confounding effect of bulk density and then estimating C and N stocks based on a fixed-mass method rather than the usual fixed-depth method, in order to compare differences across land use categories. Wehypothesized
that elevation gradient would play a determining role in C and N concentrations and stocks in native forest,
whereas tree species would be the main factor in plantations. C and N concentrations and bulk densities in
mineral soil were analyzed as repeated measures in an irregular vertical space ranging from 0–10 cm,
10–30 cm, 30–50 cm and 50–100 cm, using a linear mixed model approach. Single observations from the forest
floor were analyzed by a general linear model. Results indicated that soil depth is a more important factor than elevation gradient in native forests, though C and N concentrations and stocks diminished near human
settlements. Native forest stored on average 84.4%, 26.4% and 33.7% more carbon and 82.4%, 51.8% and 27.1% more nitrogen than bare soil, crop land and plantations, respectively. Conversion of crop and degraded land to plantations ameliorated soil degradation conditions, but species selection didnot affect carbon and nitrogen stocks.