Soil Vegetation Research Articles

Land surface temperature prediction with dual satellites and BPNN: a comparative transfer function analysis

ABSTRACT Driven by global sustainability goals, understanding land surface temperature (LST) in urban thermal environments (UTE) is crucial. This study analyses remotely sensed LST data from Aqua and Terra satellites in a rapidly growing non-tier Indian city. It uniquely integrates remote sensing and soft computational analysis to predict daytime LST using artificial neural networks (ANN). The study is categorized based on transfer functions and hyper-parameters to enhance the comprehension of LST prediction and simulation scenarios by employing Back Propagation Neural Network (BPNN) model. Results indicate that the tansig transfer function yields the best performance overall in Aqua and Terra LST prediction, while purelin performs the least effectively. This study provides evidence that soft computing techniques effectively estimate LST data, offering a valuable solution for data scarcity issues. However, the findings are specific to the study area and may vary elsewhere. Exploring alternative methods and incorporating data from other areas could potentially improve accuracy and overall performance. Future research could focus on investigating the mechanisms behind different methods and their interactions with various factors. Additionally, integrating other variables like vegetation index, soil moisture, and others could contribute to a more holistic understanding of LST dynamics and enhance predictive capabilities.

Examining the Effects of Soil and Water Conservation Measures on Patterns and Magnitudes of Vegetation Cover Change in a Subtropical Region Using Time Series Landsat Imagery

Soil and water erosion has long been regarded as a serious environmental problem in the world. Thus, research on reducing soil erosion has received continuous attention. Different conservation measures such as restoring low-function forests, closing hillsides for afforestation, planting trees and grass, and constructing terraces on slope land have been implemented for controlling soil erosion problems and promoting vegetation cover change. One important task is to understand the effects of different conservation measures on reducing water and soil erosion problems. However, directly conducting the evaluation of soil erosion reduction is difficult. One solution is to evaluate the patterns and magnitudes of vegetation cover change due to implementing these measures. Therefore, this research selected Changting County, Fujian Province as a case study to examine the effects of implementing conservation measures on vegetation cover change based on time series Landsat images and field survey data. Landsat images between 1986 and 2021 were used to produce time series vegetation cover data using the Google Earth Engine. Sentinel-2 images acquired in 2021 and Landsat images in 2010 were separately used to develop land cover maps using the random forest method. The spatial distribution of different conservation measures was linked to annual vegetation cover and land cover change data to examine the effects on the change in vegetation cover. The results showed a significant reduction in bare lands and increase in pine forests. The vegetation coverage increased from 42% in 1986 to 79% in 2021 in the conservation region compared with an increase from 73% to 87% in the non-conservation region during the same period. Of the different conservation measures, the change magnitude was 0.44 for restoring low-function forests and closing hillsides for afforestation and 0.65 for multiple control measures. This research provides new insights in terms of understanding the effects of taking proper measures for reducing soil and water erosion problems and provides scientific results for decisionmaking for soil erosion controls. The strategy and method used in this research are valuable for other regions in understanding the roles of different conservation measures on vegetation cover change and soil erosion reduction through employing remote sensing technologies.

Spatial patterns and drivers of ecosystem multifunctionality in China: Arid vs. humid regions

Ecosystem multifunctionality (EMF) refers to an ecosystem's capacity to simultaneously uphold multiple ecological functions or services. In terrestrial ecosystems, the potential patterns and processes of EMF remain largely unexplored, limiting our comprehension of how ecosystems react to various driving factors. We collected environmental, soil and plant nutrient data, investigate the spatial distribution characteristics of EMF in China's terrestrial ecosystems, differentiating between arid and humid regions and examining the underlying drivers. Our findings reveal substantial spatial heterogeneity in the distribution of EMF across China's terrestrial ecosystems, with pronounced variations between arid and humid regions. In arid regions, the EMF index predominantly falls within the range of −1 to 1, including approximately 66.8 % of the total area, while in humid regions, the EMF index primarily falls within the range of 0 to 2, covering around 55.2 % of the total area. Climate, soil, and vegetation factors account for 61.4 % and 51.9 % of the total EMF variation in arid and humid regions, respectively. Notably, climate emerges as the dominant factor governing EMF variation in arid regions, whereas soil physicochemical properties take precedence in humid regions. Specifically, mean annual temperature (MAT) emerges as the primary factor influencing EMF variation in arid regions, while the normalized difference vegetation index (NDVI) and soil biodiversity index (SBI) play pivotal roles in regulating EMF variation in humid regions. Indeed, climate can exert both direct and indirect influences on EMF. In summary, our study not only compared the disparities in the spatial distribution of EMF in arid and humid regions but also unveiled the distinct controlling factors that govern EMF changes in these different regions. Our research has contributed novel insights for evaluating the drivers responsible for mediating EMF in diverse ecosystems, shedding light on the adaptability and response mechanisms of ecosystems under varying environmental conditions.

Integrating Multiscale Geospatial Analysis for Monitoring Crop Growth, Nutrient Distribution, and Hydrological Dynamics in Large-Scale Agricultural Systems

Monitoring crop growth, soil conditions, and hydrological dynamics are imperative for sustainable agriculture and reduced environmental impacts. This interdisciplinary study integrates remote sensing, digital soil mapping, and hydrological data to elucidate intricate connections between these factors in the state of Ohio, USA. Advanced spatiotemporal analysis techniques were applied to key datasets, including the MODIS sensor satellite imagery, USDA crop data, soil datasets, Aster GDEM, and USGS stream gauge measurements. Vegetation indices derived from MODIS characterized crop-specific phenology and productivity patterns. Exploratory spatial data analysis show relationships of vegetation dynamics and soil properties, uncovering links between plant vigor, edaphic fertility, and nutrient distributions. Correlation analysis quantified these relationships and their seasonal evolution. Examination of stream gauge data revealed insights into spatiotemporal relationships of nutrient pollution and stream discharge. By synthesizing diverse geospatial data through cutting-edge data analytics, this work illuminated complex interactions between crop health, soil nutrients, and water quality in Ohio. The methodology and findings provide actionable perspectives to inform sustainable agricultural management and environmental policy. This study demonstrates the significant potential of open geospatial resources when integrated using a robust spatiotemporal framework. Integrating additional measurements and high-resolution data sources through advanced analytics and interactive visualizations could strengthen these insights.

Evaluating the relative influence of climate and human activities on recent vegetation dynamics in West Bengal, India

Assessing the relative importance of climate change and human activities is important in developing sustainable management policies for regional land use. In this study, multiple remote sensing datasets, i.e. CHIRPS (Climate Hazard Group InfraRed Precipitation with Station Data) precipitation, MODIS Land Surface Temperature (LST), Enhanced Vegetation Index (EVI), Potential Evapotranspiration (PET), Soil Moisture (SM), WorldPop, and nighttime light have been analyzed to investigate the effect that climate change (CC) and regional human activities (HA) have on vegetation dynamics in eastern India for the period 2000 to 2022. The relative influence of climate and anthropogenic factors is evaluated on the basis of non-parametric statistics i.e., Mann-Kendall and Sen's slope estimator. Significant spatial and elevation-dependent variations in precipitation and LST are evident. Areas at higher elevations exhibit increased mean annual temperatures (0.22 °C/year, p < 0.05) and reduced winter precipitation over the last two decades, while the northern and southwest parts of West Bengal witnessed increased mean annual precipitation (17.3 mm/year, p < 0.05) and a slight cooling trend. Temperature and precipitation trends are shown to collectively impact EVI distribution. While there is a negative spatial correlation between LST and EVI, the relationship between precipitation and EVI is positive and stronger (R2 = 0.83, p < 0.05). Associated hydroclimatic parameters are potent drivers of EVI, whereby PET in the southwestern regions leads to markedly lower SM. The relative importance of CC and HA on EVI also varies spatially. Near the major conurbation of Kolkata, and confirmed by nighttime light and population density data, changes in vegetation cover are very clearly dominated by HA (87%). In contrast, CC emerges as the dominant driver of EVI (70–85%) in the higher elevation northern regions of the state but also in the southeast. Our findings inform policy regarding the future sustainability of vulnerable socio-hydroclimatic systems across the entire state.

Impact of Soil Temperature and Precipitation on Vegetation Cover Over Selected Stations in Iraq

Records of precipitation and soil temperature, two of the most significant climatic elements impacting vegetation cover, were gathered as annual and monthly data over a period of 20 years from the European Center for Long-term Numerical Weather Forecasts. The goal of this study was to ascertain the impact of plant cover on climatic variations. The study’s final findings revealed that Mosul station had the greatest value of vegetation at 0.24 and Basra station had the lowest value at 0.15. The Mosul station recorded the maximum amount of precipitation, 1400 mm in the northern and central parts during the winter, and the lowest amount, 8 mm, during the fall and summer months in the districts west of the Rutba station. Using the Pearson test, it was discovered that the relationship between vegetation cover and soil temperature is inverse, and this, in turn, plays a significant role in the lack of vegetation cover in the southern regions because of nature. The desert of the region, as well as the lack of precipitation and high temperatures, is responsible for the region’s lack of vegetation. The highest value reached by the soil temperature was in the year 2018 at the Basra station.

Soil carbon, nitrogen, and phosphorus storage in juniper–oak savanna: role of vegetation and geology

Abstract. Woody-plant encroachment into grasslands and savannas has been globally widespread during the past century, likely driven by interactions between grazing, fire suppression, rising atmospheric CO2, and climate change. In the southernmost US Great Plains, Ashe juniper and live oak have increased in abundance. To evaluate potential interactions between this vegetation change and the underlying soil parent material on ecosystem biogeochemistry, we quantified soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), and δ13C of SOC in soils obtained from trenches passing through grassland, juniper, and oak patches on soils lying atop the respective Edwards and Buda limestone formations in central Texas. Soils on the Edwards formation are more shallow and have more rock outcropping than those on Buda. The δ13C values of SOC under grasslands was −19 ‰, whereas those under woody patches were −21 ‰ to −24 ‰, indicating that wooded areas were relatively recent components of the landscape. Compared with grasslands, areas now dominated by juniper or oak had elevated SOC, TN, and TP storage in soils lying atop Edwards limestone. In Buda soils, only oak patches had increased SOC, TN, and TP storage compared with grasslands. Woody encroachment effects on soil nutrients were higher in soils on the Edwards formation, perhaps because root and litter inputs were more concentrated in the relatively shallow layer of soil atop the Edwards bedrock. Our findings suggest that geological factors should be considered when predicting nutrient store responses in savannas following vegetation change. Given that woody encroachment is occurring globally, our results have important implications for the management and conservation of these ecosystems. The potential interactive effects between vegetation change and soil parent material on C, N, and P storage warrant attention in future studies aimed at understanding and modeling the global consequences of woody encroachment.

Western Caucasus regional hydroclimate controlled by cold-season temperature variability since the Last Glacial Maximum

The Caucasus region is key for understanding early human dispersal and evolution in Eurasia, and characterizing the environmental contrast between Last Glacial Maximum and Holocene is crucial for investigating human adaptation strategies to large climatic shifts. However, a paucity of high-resolution paleoclimate records leave this context largely unknown for early human populations in the Caucasus region. Based on our model-proxy comparison of high- and low-resolution records of 24 stalagmites from three caves, we find spatially distinct changes in vegetation and seasonality of precipitation, especially under glacial conditions. Supported by modern oxygen-isotope data and climate modeling, we identify a supraregional cold-season temperature control for oxygen isotopes in Black Sea speleothems, which previously had been interpreted as a local moisture-source signal. Carbon-isotope and trace-element data further suggest disproportionate changes in vegetation cover and soil dynamics at high altitudes, which would have resulted in a reduction but not a disappearance of human refugia during the Last Glacial Maximum, relative to the current interglacial. Our findings imply that abrupt climatic pressures from harsh conditions were overcome by adaptive strategies in the past.

Heavy metal contamination in the wastewater irrigated soil and bioaccumulation in cultivated vegetables: Assessment of human health risk

Heavy metal contamination in soil and accumulation in cultivated vegetables is currently an urgent ecological problem prevalent throughout the world. The study investigated the concentrations of heavy metals (Cr, Ni, Zn, Cu, and Pb) in irrigation water, soil, and vegetables grown in the vicinity of the industrial area of northern India. Furthermore, this study also assessed the health risk to the local population from consuming vegetables grown in metal-contaminated areas. In the present study, concentrations of all heavy metals in the soil remained within the acceptable limits stipulated by national standards, with the exception of Ni, which exceeded the prescribed threshold limit (Ni=75–100, Cu=135–270, Zn=300–600, Pb=250–500 µgg−1). The concentration of heavy metals in the vegetables was found maximum at the Lohta site followed by Ramnagar, Varuna, Dinapur, and Shivpur as compared to the control site (BHU). The highest concentration of Zn, Cu, Cr, Ni, and Pb was found in Spinacia oleracea followed by Amaranthus grain, Mentha spicata, Abelmoschus esculentus, Solanum melongena, Lagenaria siceraria, Solanum lycopersicum, Momordica charantia, Luffa acutangula, and least in Phaseolus vulgaris. The higher metal content of these vegetables is further supported by an increase in the metal pollution index (MPI) of wastewater-irrigated soil. The maximum DIM (Daily intake of metals) was reported in S. oleracea (0.061 μg g−1/day), whereas the minimum for P. vulgaris (0.007 μg g−1/day). On the basis of health quotient (HQ) revealed that at the Lohta, Ramnagar, Varuna Dinapur sites, HQ values of Cr, Ni, Cu, and Pb were found greater than one (>1) for both children and adults on the consumption of all tested plants. The HQ value of all heavy metals except Zn indicated their contamination in the vegetables and their health risks to the local residents. As a result, continuous monitoring and source control should be conducted for heavy metals i.e., Cr, Ni, Zn, and Pb, to ensure the region's food quality and environmental security.

A novel index for vegetation drought assessment based on plant water metabolism and balance under vegetation restoration on the Loess Plateau

Vegetation is vital to the ecosystem, contributing to the global carbon balance, but susceptible to the impacts of climate change. Monitoring vegetation drought remains challenging due to the lack of widely accepted drought indices. This study focused on vegetation, and simulated the vegetation suitable water demand and soil available water supply (calculated by Remote-sensing-based Water Balance Assessment Tool model). The standardized Vegetation Water deficit Index (SVWDI) was established by calculating the vegetation water deficit, which reflects the response of vegetation to drought. We examined the spatiotemporal evolution of vegetation drought on the Loess Plateau and evaluated the applicability of standardized vegetation water deficit index. Our findings revealed that the standardized vegetation water deficit index demonstrated an overall upward trend across different time scales from 1991 to 2020. Drought conditions were concentrated in the first 20 years of the study period, but vegetation drought on the Loess Plateau has been alleviated in the past decade. Moreover, as the time scale extended, the trend of SVWDI generally decreased, with approximately 49.50 % (1-month scale), 46.66 % (3-month scale), 47.08 % (12-month scale), and 32.16 % (24-month scale) of the grid areas experiencing increased SVWDI. The correlation between SVWDI and tree-ring width index (TRWI) performed well under all precipitation gradients, but the Palmer drought severity index (PDSI) was only highly correlated with TRWI in regions with low precipitation. In terms of the relationship with vegetation health, SVWDI demonstrated the highest correlation with the normalized difference vegetation index (NDVI) across different time scales, followed by PDSI and standardized precipitation evapotranspiration index (SPEI). This study provides insights into the evolution of vegetation drought in response to climate change. The findings can guide initiatives such as returning farmland to forest and grassland on the Loess Plateau to aid climate change adaptation strategies.

Artificially remediated plants impact soil physiochemical properties along the riparian zones of the three gorges dam in China

River ecosystem biodiversity and biogeochemical processes are shaped largely by riverside vegetation and soil. Moreover, river ecosystems provide ecological services influenced by the surrounding vegetation and soil interactions. However, the mechanisms by which artificially remediated plants (ARPs) and riparian soil interact to provide these benefits are still unclear among various ARPs. This study fills this gap and examines the impact of ARPs along the riparian zones of Three Gorges Dam (TGD) in Chongqing City, China. We sampled four varieties of ARPs from the Ruxi River Basin in the TGD. These varieties included Cynodon dactylon, Hemarthria altissima, Taxodium disticum, and Salix mastudana. Our results indicated substantial changes in soil physicochemical parameters. Comparably, T. distigum contains significantly higher soil chemical contents. Interestingly, principal component analysis explained almost 100% of the variance for all plant species in this study. Moreover, different vegetation types and soil chemical properties were positively correlated using Pearson correlation analysis (p &amp;lt; 0.05). Furthermore, all plant species exhibited strong negative correlations with physical characteristics (up to r = −1.00). Specifically, these mechanisms explain the interactions between ARPs and soil from riparian areas in the TGD. Hence, this study may facilitate ecological restoration and land management in degraded riparian areas.

Biochar increases pakchoi yield by regulating soil bacterial communities but reduces it through soil fungi in vegetable soil

Biochar increases pakchoi yield by regulating soil bacterial communities but reduces it through soil fungi in vegetable soil

The role of large mammalian herbivores in shaping and maintaining soil microbial communities of natural mineral licks: A case study on sika deer at the firebreak adjacent to the Sino-Russian border.

Mineral licks are indispensable habitats to the life history of large mammal herbivores (LMH). Geophagy at licks may provide the necessary minerals for LMH, while LMH may be ecosystem engineers of licks by altering vegetation cover and soil physicochemical properties (SPCP). However, the precise relationship between the LMH and licks remains unclear. To clarify the geophagy function of licks for LMH and their influence on soil at licks, we recorded visitation patterns of sika deer around licks and compared SPCP and microbial communities with the surrounding matrix in a firebreak adjacent to the Sino-Russian border. Our study indirectly supports the "sodium supplementation" hypothesis. Proofs included (1) a significantly higher sodium, iron, and aluminum contents than the matrix, while lower carbon, nitrogen, and moisture contents; (2) significantly higher deer visitation during sodium-demand season (growing season), along with an avoidance of licks with high iron contents, which is toxic when overdose. The microbes at the licks differed from those at the matrix, mainly driven by low soil carbon and nitrogen and altered biogeochemical cycles. The microbial communities of licks are vulnerable because of their unstable state and susceptibility to SPCP changes. Structural equation modeling (SEM) clearly showed a much stronger indirect effect of deer on microbes at licks than at the matrix, especially for bacteria. Multiple deer behaviors at licks, such as grazing, trampling, and excretion, can indirectly shape and stabilize microbes by altering carbon and nitrogen input. Our study is the first to characterize soil microbial communities at mineral licks and demonstrate the processes by which LMH shapes those communities. More studies are required to establish a general relationship between the LMH and licks to promote the conservation of natural licks for wildlife.

Dynamics of Species Richness in Understory Deciduous Teak Forest (Tectona grandis)

Teak plantation forest is a deciduous forest that sheds its leaves during the dry season. It is generally a secondary forest that is managed in a monoculture manner so that it is homogeneous. However, when teak sheds its leaves, it that may impacts the dynamics of understory species changes due to differences in environmental factors growing in the dry and wet seasons. The study observed 90 plots carried out over a year, namely two times during the dry season and 2 times during the wet season. We placed three transects around the forest edge, each (9 transects), and plotted 1 m × 1 m plots. Data collection was carried out at distances of 5, 10, 15, 20, 25, 30, 35, 40, 45 and 50 m on each transect. In each plot, the composition of the understory vegetation cover, litter cover and soil bare was observed. The research was also observed canopy openness and collected rainfall data for one year from the nearest Meteorology station. Species found were recorded for identification based on origin, life form, original habitat, and seed dispersal. The study‘s results found 57 species, 16 species only in DS, then 17 species only in WS, and 24 in both seasons. The dynamics of changes in these species are influenced by the season, which will affect the environment around the plant. Seasonal differences impact light intensity, canopy openness, leaf fall and growth, and litter thickness, which impact the understory diversity and abundance.

Integrated Analytical Hierarchy Process (AHP) and GIS techniques based Soil Erosion Susceptibility Mapping in Chite Watershed, Mizoram, India

Soil erosion is a significant form of land degradation that profoundly affects agricultural and ecosystem sustainability. The present study aimed at addressing this issue by developing precise and feasible erosion susceptibility map in Chite watershed, India, using integrated approach combining the Analytical Hierarchy Process (AHP) with Geographic Information System (GIS). To evaluate erosion susceptibility conditions, multiple causative factors including elevation, slope, drainage density, distance from streams, land use / land cover, rainfall intensity, normalized difference vegetation index, lithology, soil texture and lineament density were selected. These factors and their sub-classes were prioritized by AHP method based on their relative influence on soil erosion. Subsequently, the calculated AHP weights were utilized for generating a spatial dataset of soil erosion susceptibility through GIS technology. Accuracy assessment by the area under the ROC curve (AUC) reveals considerably acceptable results for the predicted map when compared to erosion inventory, producing an accuracy level of 0.812 (81%) and 0.922 (92%) for erosion and non-erosion points respectively. Thus, the present study manifests the efficiency of integrating the AHP and GIS techniques for erosion susceptibility mapping in the Chite watershed and this may serve as a valuable tool for sustainable land management and erosion control.

Estimation of forest canopy density through Geospatial Technology-a case study on Sathyamangalam Forest, Erode District, Tamil Nadu.

The term forest canopy density (FCD) refers to one of the important criteria used to evaluate forest's ecological health. It plays a significant role in assessing the health of the forest and serves as a key landmark for potential management actions. The canopy coverage or crown cover is referred to the percentage of the forest floor that is covered by the vertical projection of tree crowns and necessary for monitoring the condition of the forest. The present study aims to estimate the forest canopy density (FCD) through Geospatial Techniques for Sathyamangalam Forest for the period between 2016 and 2022 with SENTINEL 2A satellite data. The weighted overlay analysis method was implemented with biophysical parameters, namely, Normalize Difference Vegetation Index (NDVI), Advanced Vegetation Index (AVI), Shadow Index (SI), and Soil Bareness Index (SBI) to analyze the state of the forest and its activity. The results observed significantly that the forest canopy with 158.60 km2 in 2016 which is increased to 190.37 km2 in 2018 (1.14%) then suddenly decreased to 134.85 km2 in 2020 (2.47%). The forest canopy has recovered some of its original area with 168.83 km2 through better environmental conditions during 2021-2022 (1.52%). Therefore, Geospatial Technology plays a significant role in estimating recent changes in regional forest.

Distribution Characteristics of Carbon Density in Plant–Soil System of Temperate Steppe and Temperate Desert in the Longzhong Loess Plateau

Grassland, as a key component of the carbon cycle in terrestrial ecosystems, is vital in confronting global climate change. Characterising the carbon density of grassland ecosystems in the Longzhong Loess Plateau is important for accurately assessing the contribution of grasslands to global climate change and achieving the goal of “peak carbon” and “carbon neutral”. In this study, the Longzhong Loess Plateau was used as the research object to explore changes in the plant–soil system carbon density in two grassland types by analysing the aboveground vegetation biomass carbon density, belowground vegetation biomass carbon density, 0–100 cm soil carbon density, and ecosystem carbon density of temperate steppe and temperate desert. The results showed that the vegetation biomass (standing and living, litter, and belowground biomass), soil, and ecosystem carbon densities of the temperate steppe were significantly higher than those of the temperate desert (p &lt; 0.05). Their carbon densities were 700.51, 7612.95, and 8313.45 g·m−2, respectively. The vertical distribution of belowground biomass and soil carbon density in the temperate steppe was significantly higher than that in the temperate desert. The overall trend of belowground biomass carbon density in the temperate steppe and temperate desert showed a gradual decrease, whereas soil carbon density showed a steady increase. More than 91% and 96% of the carbon was stored in soil in the temperate steppe and temperate desert, respectively, and the belowground biomass carbon stock accounted for more than 84% of the total biomass carbon pools in both temperate steppe and temperate desert. Temperate steppe has a significant effect in improving the carbon stock of grassland ecosystems, so ecological protection and restoration of grassland should be strengthened in the future to enhance the capacity of grassland to sequester carbon and increase sinks.

Heat Treatment of Seeds to Control Invasive Common Ragweed (Ambrosia artemisiifolia), Narrow-Leaved Ragwort (Senecio inaequidens) and Giant Hogweed (Heracleum mantegazzianum)

The intended or unintentional transport of soil material contaminated with weed seeds is one of the most important drivers in the spreading dynamics of invasive alien plants (IAPs). This phenomenon can be observed at any kind of construction site. Typical transfer of soil contaminated with IAP seeds can be observed along with road construction (soil translocation) or road maintenance services (deposit of mown plant biomass). Thus, an effective inactivation of these seeds by heating can avoid the spread of IAPs substantially. In the present study, the effects of various thermal control techniques (dry air heating and wet heating with hot steam, hot water, and hot foam) on seed survival of the widespread European IAPs common ragweed (Ambrosia artemisiifolia), narrow-leaved ragwort (Senecio inaequidens), and giant hogweed (Heracleum mantegazzianum) are discussed. Dry and wet seeds which were either uncovered or covered with soil were tested for survival at different treatment temperatures and different exposure times. Results revealed that particularly dry seeds of all three species could withstand temperatures of 100 °C for at least 6 h in climate chambers. Dry seeds of common ragweed and narrow-leaved ragwort survived exposure times of up to 48 h. Wet seeds were significantly more susceptible to heat treatments. Giant hogweed seeds were completely killed after 12 h at 70 °C. The exposure of IAP seeds to hot water was generally more effective than the treatment with hot steam. The treatment with hot foam was only effective when seeds were lying unprotected on the soil surface. Dry seeds of all the three species survived hot foam application in the field when they were covered by vegetation and leaf litter or soil. Due to the robustness of the seeds, a preventive management of IAPs by an efficient control before seeds formation is substantial to avoid their further dispersal.

Temperature Matters More than Fertilization for Straw Decomposition in the Soil of Greenhouse Vegetable Field

As the largest organic carbon input to agroecosystems, crop straw can solve the problem of soil quality degradation in greenhouse vegetable fields, harmonize the balance between soil nutrients and energy, and improve soil quality to maintain the sustainable production of greenhouse vegetables. However, the microbial mechanism of the straw decomposition process under different temperatures and fertilization treatments in greenhouse vegetable soils has not been clarified. Soil samples were used to investigate the biology of straw decomposition in the soil at three incubation temperatures (15, 25, and 35 °C) through a soil incubation experiment (60 d) under different fertilization treatments. Fertilization treatments for this long-term field experiment included chemical fertilizer (CF), substitution of half of the chemical N fertilizer with manure (CM), straw (CS), or combined manure and straw (CMS). The results showed that soil hydrolase activities tended to decrease with increasing temperature during straw decomposition. Compared with the CF, organic substitutions (CM, CMS, and CS) increased soil β-glucosidase, β-cellobiosidase, N-acetyl-glucosaminidase, and β-xylosidase activities during straw decomposition. Soil CO2 emission rates were the highest at each incubation temperature on the first day, rapidly declining at 25 °C and 35 °C and slowly declining at 15 °C. The soil CO2 cumulative emissions tended to increase with increasing temperature under different fertilization treatments. PCA showed that the responses of soil enzyme activities to temperature at 7, 15, and 30 d of straw decomposition were stronger than those of fertilization. In summary, both fertilization treatment and incubation temperature could influence soil CO2 emissions by affecting soil physicochemical properties and enzyme activities during straw decomposition, whereas incubation temperature had a stronger effect on straw decomposition than fertilization, as indicated by PLS-PM and three-way ANOVA. Considering the influence for fertilization on the straw decomposition process at different incubation temperatures, the straw applications (CMS and CS) were more suitable to temperature changes.

Effects of microplastics on N2O production and reduction potential in crop soils of northern China

Microplastics (MPs) pollution are found to be increasing in vegetable soils and potentially affecting N2O production and their associated pathways; however, its specific effects remain unclear. Here, we selected two common MPs, PE and PP at four different concentration levels of 0, 0.5, 1.5 and 3%, and conducted several incubation experiments aiming to explore soil bacterial and fungal N2O production. Results showed that the bacteria were the main contributors for the production of N2O, regardless of the absence or presence of MPs; and its contribution was decreased with increasing concentrations of PE and PP. The nosZ clade I and II genes were positively correlated with N2O reduction rates, indicating a combined regulation on soil N2O reduction. PE significantly inhibited the bacterial nitrification and denitrification, but did not affect the total N2O production rates; while PP significantly reduced both the bacterial and fungal N2O production rates. The resistance of fungal N2O production to MPs pollution was stronger than that of the bacterial N2O production. It highlights that the MPs pollution could reduce the potential of N2O production and reduction, and thus disturb soil nitrogen cycling system; while the inhibition on N2O production via bacteria and fungi varies with different types of MPs. This study is conducive to an improved and more comprehensive understanding of the ecological impacts of MPs within the agroecosystem.