Understanding the spatiotemporal changes in soil organic carbon (SOC) and their driving factors is an important prerequisite for decision-making in maintaining sustainable agricultural development and addressing climate change. A total of 1219 cropland topsoil SOC data (0-20 cm) collected from southern Jiangsu Province of China in 1980, 2000, and 2015, and geostatistical sequential Gaussian simulation were used to identify the changes in the spatiotemporal patterns of SOC during the period of 1980-2015. Results showed that the changes in SOC within the different time periods were significantly different, with a net increment of 3.65 g kg-1 during the period of 1980-2000 and a net decrement of 2.32 g kg-1 during the period of 2000-2015. Significant SOC accumulation occurred throughout the study area during 1980-2000, while SOC decline became predominant in the southeast during 2000-2015. Overall, the SOC contents for 60% of the study area increased significantly over the entire 35-year period. The SOC increase during the first two decades (1980-2000) was largely attributed to the increasing soil C input that resulted from the enhanced crop productivity by chemical fertilizers, while the stagnant soil carbon inputs associated with the rapid urban expansion were the primary reason for constraining cropland SOC accumulation in the subsequent 15 years (2000-2015). These findings highlight the importance of balancing agricultural development and urbanization processes to maintain SOC levels, and may also provide some guidance for planning cropland soil C management strategies in many areas that are undergoing similar urbanization processes.
Exploring the driving factors of ecosystem services (ESs) trade-offs/synergies is crucial for ecosystem management, especially in ecological conservation red line (ECRL) areas that maintain regional and national ecological security. Soil conservation (SC), water yield (WY) and carbon sequestration (CS) were simulated in the Beijing ECRL areas. Geographical weighted regression was used to explore the trade-offs/synergies, and the geographical detector was applied to quantitatively identify their driving factors. Results show that (1) the SC and CS show marked synergy which characterized more than 80% of each ECRL area; the proportion of the space area of trade-off and synergy between SC and WY, and WY and CS was roughly 3 to 7 and 4 to 6 in each ECRL area, respectively. (2) The synergy of the three pairs of ESs was most sensitive to terrain factors. The precipitation erodibility of soil and its necessity for vegetation make it a determinant of the trade-off between SC and CS; temperature was the determinant in the trade-off between WY and CS, with an explanatory power of 32.8%; potential evapotranspiration was best able to explain the spatial distribution of the trade-off between SC and WY. (3) The interaction between precipitation and other factors had the greatest explanatory power on the spatial relationship between SC and WY. Precipitation and relief amplitude are the main interactive factors respectively affecting the spatial trade-off and synergy between SC and CS. The trade-off and synergy between WY and CS were most sensitive to the interaction between climate factors and terrain factors.
Restoration has now emerged as a global priority, with international initiatives such as the “UN Decade on Ecosystem Restoration (2021-2030)”. To fulfil the large-scale global restoration ambitions, an essential step is the monitoring of vegetation recovery after restoration interventions. The aim of this study was to evaluate the utility of remotely-sensed vegetation indices, Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI), to monitor the rate of forest regeneration across a tropical forest restoration project area in Kibale National Park, Uganda. As a result, we observed non-linear patterns in NDVI and EVI across the first 25 years of recovery. Both NDVI and EVI increase for the first 10 years of forest regeneration. This “greening” phase could be used as the indicator of successful onset of forest recovery. In particular, the decline of elephant grass, which suppresses the natural regeneration of trees in our area, can be detected as an increase in NDVI. Primary forests differed from the 25-year-old regenerating forests based on the unique combination of low mean and low seasonal variation in EVI. Our results, therefore, suggest that the long-term success of forest restoration could be monitored by evaluating how closely the combination of mean, and degree of seasonal variation in EVI, resembles that observed in the primary forest.
Land degradation is one of the major global environmental issues that need serious attention. The land itself is a complex system regulating myriads of processes and perturbation in anyone these would certainly lead to the stimulation of land degradation. Among these, fly ash (FA) dumping is one of the common-practices, which has been adopted to overcome land-use disruption and other health hazards. However, this practice has become a driving factor for FA-induced land degradation. Therefore, in purview to tackle this issue, the present article is aimed to identify and suggest plausible sustainable practices to restore and manage FA contaminated sites. It preliminarily deals with the systematic exploration and identification of FA-based and associated contaminated lands via geospatial technology with a brief focus on monitoring its different contaminant profiles in the FA and soil systems. Moreover, the article emphasizes identifying the potential local plant species in the FA-contaminated regions to understand the local people’s demands. Following this, it would suggest the major sustainable approaches to expedite the restoration of FA contaminated lands along with the key highlights of their bottlenecks, while the ground implementation. Nevertheless, the article aimed to unravel the recommended prospects to address those bottlenecks to develop an efficient restoration enterprise during the Decade on Ecosystem Restoration (2021-2030).
Fly ash (FA) is the 80% of coal burnt by-product of thermal power plants (TPPs), its disposal in landfills causes environmental and health issues. The amount of FA production is increasing continuously to fulfil the worldwide energy for demand, which possibly never find a practically safe method for FA dumping. Its fine particle size disperses in the air and causes air pollution and water pollution is resulted due to slurry erosion from FA dumps and contamination by leachate. Health issues and environmental concerns due to fly ash landfills/dumpsites can be prohibited by covering with phytoaccumulator plant species. Limitations of plant growth in FA includes alkaline pH, contain metals such as Cr, Cd, As, Hg and Pd, toxic level of B, pozzolanic properties of FA and lack of microbial activity. Generally, the phytoremediation process is slow therefore, to accelerate the phytoremediation process FA require organic amendments and bio-fertilizers. This article focuses on the role of naturally occurring plants in stabilization of FA dumpsite and physiochemical changes in FA. This review summarises the different holistic approaches of rehabilitations of FA landfills and also compiles how to convert FA landfills into useful landfills for bioenergy productions. Utilization of organic matter and industrial waste has been proved to provide essential nutrients for plant establishment and heavy metal accumulation. The outcomes of this learning are beneficial for classifying site-specific ecological restoration of FA landfills through holistic approach.
Land degradation due to soil erosion presents a challenge for sustainable development. We investigated the impact of land use type and land management practices on runoff and sediment yield dynamics in the northwestern highlands of Ethiopia. The study area included 14 zero-order catchments with a surface area ranging from 324 m2 to 1715 m2. V-notch weirs produced from plastic jars were introduced as measuring alternatives that met local constraints. Runoff depth at the weir was registered at 5-min intervals during two rainy seasons in 2018 and 2019. Rainfall was measured using tipping-bucket rain gauges. Runoff samples were collected in 1-L bottles and suspended sediment concentration (SSC) was determined. The mean event runoff coefficient ranged from 3% for forests to 56% for badlands. Similarly, the mean annual sediment yield (SY) was lowest for forests (0.8 Mg ha-1 yr-1) and highest for badlands (43.4 Mg ha-1 yr-1), with significant differences among land use types (14.8 Mg ha-1 yr-1 in cropland, 5.7 Mg ha-1 yr-1 in grazing land, and 2.9 Mg ha-1 yr-1 in plantations). Soil organic matter (SOM) reduced runoff and SY, necessitating the consideration of agronomic and land management practices that enhance SOM. Annual SY decreased exponentially with the rock fragment cover (RFC). In fields where RFC was less than 20%, collecting rock fragments for installing stone bunds resulted in a net increase in SY. Rehabilitating badlands and enhancing SOM content in croplands can substantially reduce catchment SY and, hence considerably contribute to the sustainability of this type of environment.
This paper reported the recovery of desert plant communities after twenty years of oil-derived hydrocarbon contamination in desert habitats of Kuwait, caused by the First Gulf War (1990 – 1991). The hypothesis that certain native desert plant species can tolerate weathered oil-polluted soils with oil breakdown products (i.e., polycyclic aromatic hydrocarbons ( PAHs)) and have the potential to function as bioindicators and phytoremediator species for oil-polluted soil was tested. A field survey of 200 quadrat sampling plots at seven hydrocarbon-contaminated and unpolluted desert areas in Kuwait was performed that recorded 42 plant species, with Haloxylon salicornicum, Cyperus conglomeratus and Rhanterium epapposum as the most dominant species. Analysis of plant tissues indicated plant uptake and accumulation of some PAHs. H. salicornicum was used as a representative species in a controlled field study that included growth of plants in hydrocarbon-polluted and unpolluted soils in two separate desert areas under similar growth conditions. Results showed a significant decrease in plant biomass in oil-contaminated soil compared to those from the uncontaminated site. However, the plants appeared green and healthy in both sites, and showed no overt stress. The results suggest that some desert plant communities exhibit signs of recovery after severe oil pollution, and that H. salicornicum may serve as a phytoremediator of oil-contaminated desert soils. Our results also demonstrated that some desert plant communities could be cultivated in oil fields to reduce hydrocarbon contamination and provide guide to other ecosystem services through improving soil quality and biodiversity.
Biota play major roles in soil function and are highly sensitive to any disturbances including land degradations. The objective of research was to evaluate the effectiveness of different methods used to determine soil quality in sandy soil, in particular to compare the microarthropod and vegetation indices. The following soil fauna indices were used: Collembola and Acari abundance, QBS-ar index, decomposition rate, feeding activity. The Ellenberg index was used as a vegetation indicator, in which the response to pH, nutrients, and moisture was analysed. We based on an experiment conducted at a former military site in the Czech Republic. Soil quality was determined at two sites which differ slightly in nutrient content. Collembola abundance, feeding activity, and QBS-ar index were highly sensitive to minor differences in nutrients. In the group of vegetation indices, only the response to pH was significant. All analysed indices showed better biological quality in soils with higher nutrient content. Collembola were positively correlated with all vegetation indicators, which may indicate a close relation of springtails to certain plant species or similar habitat requirements. Finally, we indicate the usefulness of biological indicators for monitoring the quality of soil, which can be adopted when making various decisions concerning land use.
Large scale changes in land use pattern such as deforestation and machine-intensive farming process have increased carbon concentrations in atmosphere which negatively affects agricultural sector. Cross-disciplinary approaches were applied to investigate the land use changes and their impacts on the soil properties over Kanshi watershed. The results revealed that vegetation cover has been declined over the Kanshi catchment area during the last two decades. The deforestation and urbanization are the basic reasons for the fall of water tables in the Kanshi catchment area. Furthermore, the decreasing trend of rainfall and increasing trend of temperature was estimated during the last two decades. While the water discharge was decreased by 44.15 % during the last two decades in the Kanshi watershed. This substantial and significant change resultant due to climate change or increased intercession of anthropogenic activities on the earth surface. The highest stream flow was found in 1992 in the Kanshi catchment due to heavy rainfall. But in 2019, flow was on its peak value. Such variations in flow of stream increase due to fluctuations in rainfall pattern and vegetation cover resulted land degradation. 85% of local community is agreed that extensive agricultural practices, population growth, settlement patterns and brick industry have significant negative impact on vegetative cover and water discharge.
Tropical forest and swidden agriculture are declining, while commercial plantation is continuously expanding. However, little is known about the mechanisms, processes and trends of the tropical forest-swidden-plantation (FSP) nexus. Global ongoing initiatives including the UN-REDD Programme, not only have repeatedly emphasized the significance of conserving forests, reforestation and afforestation, but re-pushed swidden agriculture to the forefront of a long-standing international debate of climate changes and biodiversity. Many facets limit our understanding of swidden agriculture. The lack of geographic and demographic data and their dynamics across the tropics undoubtedly further aggravate this situation since the first appeal of eradication of shifting cultivation by the FAO. Although recent studies have enriched significantly our knowledge of forest loss and plantation expansion, previous research has proceeded separately and has yet to be integrated under the umbrella of sustainable swidden agriculture. Efforts are needed to investigate the dynamics of the FSP nexus for sake of a synergetic goal of climate mitigation and poverty alleviation.
A comprehensive evaluation indicator system is needed to provide a integrated assessment of the degree of sloped cropland degradation. We employed bibliometrics to perform statistical analysis on research studies involving cropland degradation. Frequency analysis was then used to identify high-frequency indicators with which to construct a total index set (TIS) for evaluation of the degree of sloped cropland degradation in black soil region. In addition, soil measurement data from sloped cropland in Baiquan and Keshan Counties, Heilongjiang province, China, were used as a basis to construct a minimum index set (MIS). The TIS included A-horizon thickness, clay content, organic matter content, pH, slope gradient, ridge-slope angle, gully density, bulk density, large water-stable aggregate content, soil cation exchange capacity, and crop yield. The first six of these were included in the MIS. In the studied area, undegraded soil, mildly degraded soil, and moderately degraded soil and above accounted for 7%, 48% and 45% of investigated sloped croplands, respectively. Slope gradient is one of the main factors affecting soil degradation. Soil degradation mainly presented as worsening of soil physicochemical characteristics. In addition, downslope and small-angle ridge cultivation are benefit for soil organic matter maintenance and the soil structure and nutrient retention capacity is better than soil with contour or large-angle ridge cultivation. The reason might be that downslope and small-angle ridge cultivation are usually employed on soil with small slope. The study results provide a scientific basis for improving the quality and productivity of sloped cropland in black soil region.
Araucaria araucana is an iconic long-lived endangered tree species exclusively distributed in Southern Chile and Argentina. Araucaria forest ecosystems provide a myriad of ecosystem benefits to local aboriginal Mapuche-Pehuenche communities. Among the main current threats for Araucaria forests are the increasing frequency and severity of wildfires and overgrazing. This study evaluates the effect of uncontrolled livestock grazing on soil quality indicators linked to critical functions relevant to forest regeneration and ecosystem service provision. We also aim to determine a set of soil quality indicators that are sensitive enough to grazing pressure, so they are useful as early indicators of degradation or the effectiveness of restoration practices. This study evaluated twenty soil quality indicators in two contiguous degraded forest areas with contrasting grazing pressure. We observed a substantial shift in forest structure, a reduction in tree coverage on the overgrazed sites. Overgrazing has produced significant deterioration of most soil physical, chemical, and biological quality indicators making soil conditions less suitable for seed germination and sapling establishment. We also observed an alteration in C, N, and P biogeochemical pools. Besides, soil physical indicators alterations suggest changes in these soils' hydrological behavior, potentially reducing water storage, availability, and increasing runoff. We show that uncontrolled grazing in native protected areas degrades soils and forest health, restricting forest regeneration and potentially accelerating erosive processes. Our results emphasized the need for an improved conservation plan for these forests that systematically evaluates and monitors livestock grazing and all its direct and indirect effects, including soil quality.
Forest transition theory posits that socioeconomic development in a country or region may cause its forestland to shift from net loss to net gain. However, forest transition may also occur under various policies, resulting in forest gains in some regions but deforestation in other regions. We used the telecoupling framework to address this crucially important issue that has rarely been examined. Using time series satellite images and statistical yearbook data from 2000 to 2020, this study seeks to understand land use change patterns, the corresponding regional spillover effects, and driving forces behind such patterns in Zhejiang Province, China. The results show that large-scale continuous deforestation has taken place since 2000, causing a total loss of forestland by 186,014 ha. In parallel with this forest loss and a slight decrease in arable land, urban construction land has soared by 169.45%. We found that developed municipalities such as Hangzhou witnessed increases in urban land at the expense of large-scale deforestation in underdeveloped municipalities such as Lishui. We believe that this cross-region land change pattern may arise from the Balance of Arable Land System (BALS) policy that seeks to achieve a goal of no net loss of cropland. Whatever land use policy—such as the BALS policy—must strike a good balance between competitive land uses that have different objectives such as residents’ living, ecology, and production. In addition to enriching the forest transition theory, this study provides a solid basis for future land use decisions in developing regions or countries.
Clear-cutting means forest removing (stem only) and is the most common type of forest harvesting but undoubtedly has a negative impact on the C budget in soils. This work aimed to describe responses of soil organic matter in the forest soils to forest removing under temperate climate conditions of lowland and mountain regions in south-western Poland. Using advanced instrumental analysis, like EPR, 1H NMR and FT-IR spectroscopy it has been found that clear-cutting, alters C cycling and accelerates decomposition in the forest floor leading to loss of humic fractions in the investigated soils. In the mountain forests the more labile, low-molecular fulvic fraction decreased as the effect of harvesting practice. The transformation of organic matter after clear-cutting resulted in the loss of less humified organic matter containing humic substances of less polymerised molecules. Analysis of the semiquinone radical structures and concentrations showed a decrease in radical concentration observed for HA from mountain clear-cut areas compare to the undisturbed forest. Results presented in this paper have proved less aliphatic character of humic acid molecules from the lowlands, compared to the mountain forest as the effect of clear-cutting. Harvesting practices in mountain regions should be approached with particular care due to the risk of erosion of exposed surfaces and soils containing less humified and less stable organic matter than in the lowlands. Humic fractions of higher solubility, less stability and tendency to migrate through the soil profile may favour the leaching of nutrients and consequently cause the eutrophication of waters.
A four-year field experiment was carried out to evaluate an integrated use of saline water for the saline soil reclamation in Hebei Province of North China. A landscape shrub (Caryopteris × clandonensis ‘Worcester Gold’) was cultivated using drip irrigation scheduled by rootzone soil matric potential control at five levels of water salinity (ECi): 0.8, 3.1, 4.7, 6.3, and 7.8 dS·m−1. Soil matric potential control was applied using a threshold of −5, −10, −15, and −20 kPa in the first, second, third, and fourth year, respectively. After four growing seasons, the saline soil (initial ECe value of 27.8 dS·m−1) was reclaimed to slightly saline soil for 0–1 m depth (4.1–7.2 dS·m−1) under drip irrigation with saline water of ECi < 7.8 dS·m−1. The salt leaching efficiency of root zone soil was highest in the first year and lowered year-by-year. The plants strongly responded to the different soil water and salinity regime. Significant decreases in survival rate, plant growth, and shoot dry weight in response to increasing ECi were found. To achieve a relative survival rate of >50%, the threshold salinity of irrigation water for ‘Worcester Gold’ cultivation was 7.8, 7.0, 5.6, and 5.3 dS·m–1, for the first, second, third, and fourth growing season, respectively. It is recommended to use an inter-seasonal evolving matric potential threshold of −10 kPa for dry season of the third year, −15 kPa for rainy season of the third year and dry season of the fourth year, and −20 kPa for rainy season of the fourth year.
Sustainable agronomic practices are tried all over the world to promote safe and eco-friendly crop production. Therefore, in the present study, the effect of seed endophytic bacteria and its consortia on soil biochemical property, soil nutrient, and yield of chickpea (Cicer arietinum L.) under field and pot conditions are investigated. Both the experimental results proved a significant increase in total soil organic carbon (OC), electric conductivity (EC), organic matter (OM), soil nutrient like available N, P and K content and important soil enzymes like dehydrogenase (DHA), beta glucosidase, alkaline phosphate, and urease was observed under the Enterobacter hormaechei BHUJPCS-15 (T1), Enterobacter cloacae BHUJPCS-21 (T2) and combined T3 (consortia of T1 and T2) treatments. Similarly, a significant increase in the grain yield (27-45% and 57-73%) in microbial treatment was found in pot and field experiments, respectively than control. In addition, whereas the higher plant biomass (14-38% and 42-78%) was recorded in the treated plant over the control plant. Similarly, the plant photosynthetic pigment (Chl a, b, total Chl) were also increased in the microbial treated plant than the control untreated chickpea plant. Our present study highlights the significance of sustainable agronomic practices for improving the soil quality and agricultural yield while reducing adverse impacts of chemicals by the use of seed endophytic microbes and their consortia.
Despite many studies explored the effect of livestock grazing on plant communities, the response of species composition and diversity to livestock grazing in arid rangelands remain ambiguous. This study examined the effects of livestock grazing on plant communities in arid steppe rangelands of North Africa. Plant diversity of annual species, perennial species and all species combined was measured and compared between grazed and grazing-excluded areas. We also examined the relative importance of species turnover and community nestedness. Moreover, the effects of livestock grazing on beta diversity at local among transects and landscape among sites scales were examined using the multiplicative diversity partitioning. Results revealed that livestock grazing significantly decreased the alpha diversity of all species combined and the diversity of annual plants. Livestock grazing induced a shift in plant community composition where most of species composition variation (~74%) was due to infrequent species replacement ‘turnover’ between the two management types rather than nestedness (~26%). Results revealed also that among transects, beta diversity was higher in grazed steppes than in grazing-excluded steppes. Whereas, among sites, beta diversity was lower in grazed steppes compared to grazing-excluded steppes. These findings suggest that livestock grazing in arid steppe rangelands increases the variation in plant species composition at a local spatial scale and engenders vegetation homogeneity at landscape spatial scale. Therefore, the implementation of appropriate management practices such as short-term grazing exclusion is mandatory to prevent these ecosystems from large scale biotic homogenization.