Soil Vegetation Research Articles

Effects of grazing and vegetation on Daurian Pika populations in northern Mongolia

Abstract Daurian Pika (Ochotona dauurica) are steppe-dwelling burrowing mammals with the potential to have large effects on central Asian grasslands due to their extensive range, propensity to occur at extremely high density, and roles as ecosystem engineers and important prey species. The few studies that have been done are mostly from northern China and Russia, while little research has been done in the majority of their range in Mongolia. We studied a population of Daurian Pika in the Darhad Valley of northern Mongolia, near the southern edge of the permafrost, where climate change is progressing rapidly. We evaluated pika populations at 87 random plots across a large 40 × 125 km area and assessed the impact of factors related to vegetation cover, grazing, and soils that predicted their occupancy and an index of their density (number of active burrows). We found that pikas were more likely to occur in areas with taller grass and higher forb cover, and burrow densities were higher in areas with low or moderate grazing and lower soil moisture. In summer, pikas mainly foraged on grass compared with forbs—while in fall, forbs appeared to be selected for in haypiles. Dense pika burrow systems had taller grasses and forbs in their immediate vicinity, suggesting that in some cases, pika could help promote plant growth for other grazers. Long-tailed Ground Squirrel (Urocitellus undulatus) was the second most abundant small mammal in our study sight and selected for areas with high cover of overgrazing indicator species and for short forbs, providing little evidence for competition with Daurian Pika. Our results suggest that shorter grass (~1 cm) can decrease pika occupancy by 75%, while heavy grazing may decrease burrow density by 66% in dry soils. With grazing pressure in Mongolia increasing dramatically since the 1990s, future research is strongly needed to assess the impacts of grazing on this keystone species.

The Spatial Dynamics of Diazotrophs in the Forefield of Three Tibetan Glaciers.

Nitrogen is often a limiting nutrient for microbial communities and plants in glacier forefields. Nitrogen-fixing microorganisms (diazotrophs) play an important role in providing bioavailable nitrogen, with their composition determining the nitrogen-fixating capacities. This study investigates the spatial and temporal dynamics of diazotrophs in the forefields of three Tibetan glaciers: Qiangyong, Kuoqionggangri, and Longxiazailongba. We collected soil samples from recently deglaciated barren grounds, and also along an ecosystem succession transect at Kuoqionggangri glacier, encompassing barren ground, herb steppe, legume steppe, and alpine meadow ecosystems. Our finding revealed abundant and diverse diazotrophs in the recently deglaciated barren ground. They are taxonomically affiliated with anaerobic Bradyrhizobium, Desulfobulbus, and Pelobacter, which may be relics from subglacial sediments. The vegetated soils (herb steppe, legume steppe, and alpine meadow) were dominated by phototrophic Nostoc and Anabaena, as well as symbiotic Sinorhizobium. Soil physicochemical parameters, such as soil organic carbon, pH, and nitrate ion, significantly influenced diazotroph community structure. This study highlights the critical role of diazotrophs in mitigating nitrogen limitation during early ecosystem development in glacier forefields. Understanding the distribution and ecological drivers of diazotrophs in these rapidly changing environments provides insights into biogeochemical cycling and ecosystem resilience under climate change.

Production and Subsequent Application of Different Biochar-based Organic Fertilizers to Enhance Vegetable Quality and Soil Carbon Stability

Production and Subsequent Application of Different Biochar-based Organic Fertilizers to Enhance Vegetable Quality and Soil Carbon Stability

Carbon mineralization potential and nutrient dynamics in soils under vegetation types and soil depths at Luot mountain

Soil mineralization is a crucial soil process that improves soil physical properties, enhances carbon sequestration, and provides essential minerals and available nutrients for plant growth. This study was conducted at five vegetation types and soil depths at Luot mountain area, located in VNUF campus, Hanoi city. Samples were incubated in the dark at 25°C and measured at intervals of 1, 2, 5, 10, 15, 25, 35, and 40 days in the laboratory to determine C-CO2 respiration from soils. The study showed that CO2 emissions were highest in topsoils and decreased with deeper soil depths. Mineralized C-CO2 decreased from Shrubs > Acacia + Native species (NS) > Pinus + NS > Native species > Control. CO2 emissions peaked early in the incubation period and then stabilized in the 40-day incubation period. Larger aggregates (≥ 5mm) decreased significantly under most vegetation types, except for Shrubs, where the reduction was minimal. Aggregate size ≥3mm increased post-incubation, notably under Pinus + NS and Native species, with smaller aggregates also increasing slightly. Organic matter content was highest in the topsoil but decreased post-incubation due to microbial C mineralization. There was an increase in soil organic matter at 10-20 cm and 20-40 cm layers after incubation, especially under Shrubs. Available nitrogen slightly increased in soils post-incubation for most vegetation types. Phosphorus content increased post-incubation, peaking under Shrubs, while potassium levels were generally poor but increased during incubation. The study found that C-CO2 mineralization was strongly associated with soil porosity and pH, suggesting that higher porosity and optimal pH enhance mineralization, with organic matter content being crucial for available nutrient cycles in soils.

Optimal vegetation coverage from the perspective of ecosystem services in the Qilian Mountains

Abstract The Qilian Mountains (QLMs) serve as a vital ecological security barrier in the northwest China, determining the optimal fractional vegetation cover (FVC) of different land-use types is crucial for ecological restoration and protection. Based on the normalized vegetation index, meteorological data, soil data and land-use data, the InVEST model, bivariate spatial autocorrelation and elastic analysis, we calculated the water conservation, soil conservation and carbon storage, analyzed the spatio-temporal distribution characteristics of FVC and ecosystem services (ES) and the correlation between them. This study aims to evaluate the optimal FVC of the different land-use types and vegetation restoration’s effect on it in the QLMs. The results showed that the FVC and ES showed an increasing trend from 2000 to 2020, with a spatial distribution pattern of high values in the southeast and low values in the northwest. There was a significant and positive correlation between FVC and ecosystem service functions (p < 0.05), FVC had the most obvious effect on soil conservation, followed by water conservation. The optimal FVC varied by land-use type, with its value between 0.4 and 0.48 for forest land, 0.24 and 0.30 for grassland and 0.19 to 0.20 for unused land. In the eastern of the QLMs, nearly 70% of the forests and 50% of the grasslands exceeded the optimal vegetation coverage, while 36% of the grasslands and 62% of the unused lands were under-covered in the western of the QLMs. The findings suggest that differentiated ecological restoration and management measures should be formulated according to the status of vegetation restoration, to enhance the comprehensive capacity of ecosystem services in the QLMs.

Calcium Silicate Application as a Salt Stress Mitigation Strategy for Vegetables in the Salt-affected Soils of Sandy Plains of Kerala, India

Soil salinity inhibits plant growth due to osmotic stress and reduced plant and water uptake. In the Onattukara sandy plains of Kerala, saltwater intrusion is a major problem in several panchayaths near the coastal area. In uplands also, cultivation is not possible due to the salt stress from saltwater intrusion. One of the strategies for removing the inhibitory effect of salt stress on plant growth is the application of beneficial nutrients to the plants. Therefore, a study was carried out to understand the effect of calcium silicate application on mitigating salt stress in vegetables and using tomato as a test crop. A detailed germination study was conducted in laboratory conditions prior to pot culture experiment to find out the critical level of salinity for tomato and two salinity levels 30mM and 40 mM NaCl were selected for the pot culture experiment. For accessing the effect of the various levels of calcium silicate on reducing salt stress in tomato, a pot culture experiment was conducted in Onattukara region (AEU 3) in completely randomized design with ten treatments replicated thrice with varying levels of CaSiO3 from 100 kg ha-1 to 150 kg ha-1. The treatments had a significant effect on all the biometric characteristics and yield attributes of the crop. The highest fruit weight, fruit per plant, and fruit yield were observed in treatment with soil test-based NPK recommendation and 125 kg ha-1 of CaSiO3 applied. It was also observed that the relative water content was higher and the water saturation deficit was lower in this treatment. CaSiO3 application @125 kg ha-1 along with soil test-based recommendation of NPK can be recommended as a salt stress mitigation strategy for boosting vegetable production in the salt-affected soils of sandy plains of Kerala.

Segmentation uncertainty of vegetated porous media propagates during X-ray CT image-based analysis

Abstract Background and Aims Phase segmentation is a crucial step in X-ray computed tomography (CT) for image-based analysis (CT-IBA) to derive soil and root information. How segmentation uncertainty (SU) affects CT-IBA of vegetated soil has never been explored. Methods We proposed a new framework enabled by machine learning to measure SU and its propagation from the first to the second-order parameters derived from CT-IBA. Vegetated glass beads of varying moisture contents and plant species were CT scanned. Segmented images were used to determine volumetric fractions and morphological properties of each phase for determining the absolute permeability (K). Results Although the root phase is susceptible to SU, its influence on CT-IBA is minimal when the root content is low. However, its SU was magnified when the water phase is present. The grain phase has a lower SU susceptibility, but due to its large volumetric content, the IBA can be affected significantly. Fine roots were found to exhibit higher SU than coarse roots, indicating that root architecture has an effect on the segmentation of the root phase, and thus higher-order properties like K. Conclusion Segmentation of the grain phase is sensitive to SU. A small SU will lead to a remarkably erroneous estimation of pore morphological properties and K. To reduce SU, we suggest reducing the water content to a discontinuous state of a cohesionless vegetated porous media specimen before sending it for CT scanning and IBA. However, caution should be taken when fine roots were dried and experienced excessive shrinkage.

Climate Change May Increase the Impact of Coastal Flooding on Carbon Storage in China’s Coastal Terrestrial Ecosystems

Climate warming exacerbates the deterioration of soil and degradation of vegetation caused by coastal flooding, impairing ecosystem climate-regulating functions. This will elevate the risk of carbon storage (CS) loss, further intensifying climate change. To delve deeper into this aspect, we aimed to integrate future land use/land cover changes and global mean sea-level rise to assess the impact of coastal floods on terrestrial CS under the effects of climate change. We compared the 10-year (RP10) and 100-year (RP100) return-period floods in 2020 with projected scenarios for 2050 under SSP1-26, SSP2-45, SSP3-70, and SSP5-85. The study findings indicate that CS loss caused by coastal flooding in China’s coastal zones was 198.71 Tg (RP10) and 263.46 Tg (RP100) in 2020. In 2050, under the SSP1-26, SSP2-45, and SSP3-70 scenarios, the CS loss is projected to increase sequentially, underscoring the importance of implementing globally coordinated strategies for mitigating climate change to effectively manage coastal flooding. The value of CS loss is expected to increase in 2050, with an anticipated rise of 97–525% (RP10) and 91–498% (RP100). This highlights the essential need to include coastal flood-induced CS changes in carbon emission management and coastal climate risk assessments.

Snowmelt-mediated isotopic homogenization of shallow till soil

Abstract. The hydrological cycle of sub-arctic areas is dominated by the snowmelt event. An understanding of the mechanisms that control water fluxes during high-volume infiltration events in sub-arctic till soils is needed to assess how future changes in the timing and magnitude of snowmelt can affect soil water storage dynamics. We conducted a tracer experiment in which deuterated water was used to irrigate a plot on a forested hilltop in Lapland, tracked water fluxes of different mobility and monitored how the later snowmelt modifies the labelled soil water storage. We used lysimeters and destructive soil coring for soil water sampling and monitored and sampled the groundwater. Large spatiotemporal variability between the waters of different mobility was observed in the subsurface, while surface water flow during the tracer experiment was largely controlled by a fill-and-spill mechanism. Extensive soil saturation induced the flow of labelled water into the roots of nearby trees. We found that labelled water remained in deeper soil layers over the winter, but the snowmelt event gradually displaced all deuterated water and fully homogenized all water fluxes at the soil–vegetation interface. The conditions required for the full displacement of the old soil water occur only during a snowmelt with a persistently high groundwater table. We propose a conceptual model where infiltration into the soil and eventual soil water replenishment occur in three stages. First, unsaturated macropore flow is initiated via the surface microtopography and is directed towards the groundwater storage. The second stage is characterized by groundwater rise through the macropore network, subsequent pore water saturation and increased horizontal connectivity of macropores. Shallow subsurface lateral fluxes develop in more permeable shallow soil layers. In the third stage, which materializes during a long period with a high groundwater table and high hydrological connectivity within the soil, the soil water is replenished via enhanced matrix flow and pore water exchange with the macropore network.

Effect of different concentrations of Copper (Cu) on growth sttributes and bioaccumulation in <em>Celesia argentea</em> and <em>Amaranthus hybridus</em>

Cultivation of vegetables in polluted soil has been on the increase following the perceived fertility of such soil. This study investigated the growth performance and bioaccumulation of copper (Cu) in Amaranthus hybridus and Celosia argentea planted in Cu polluted soil. The research was conducted at the University of Ilorin botanical garden. Vegetable seedlings were transplanted into soil pots pre-treated with Cu - 100, 200 and 400 mg/kg; denoted as T1, T2 and T3 respectively, and a control pot without Cu treatment. Amaranthus hybridus grown in soil polluted with 200 mg/kg of Cu gave the highest stem length at 1, 2 and 3 weeks after transplanting (WAT) i.e., 3.98, 5.00 and 7.05 cm respectively. There was no significant difference in stem girth and leaf length and breadth of Celosia argentea grown in 200 mg/kg Cu (P<0.05). However, leaf length and breadth and number of leaves were significantly higher (P<0.05) in C. argentea grown in soil with same Cu concentration at 3 WAT i.e., 4.63 cm, 2.27 cm and 9.17 respectively. Bioaccumulation pattern recorded in A. hybridus indicated that those grown in soil polluted with 100 mg/kg of Cu have the highest elemental Cu accumulation (73.77 mg/kg). Amaranthus hybridus and Celosia argentea recorded highest wet and dry weights in those planted in soil polluted with 200 mg/kg of Cu.

Soil-forming factors controlling Technosol formation in historical mining and metallurgical sites in the high-alpine environment of the Tatra Mountains, southern Poland

The Tatra Mountains are a unique Central European alpine ecosystem where the non-anthropogenic soil cover and soil-forming processes are well recognized. However, the Technosols in the area’s high-mountain environment have not been studied in detail to date. Therefore the aim of this study was to identify the most important soil-forming factors controlling the properties of Technosols developed in historical mining and metallurgical sites in the Tatra Mountains of southern Poland active from the 15th Century until the end of the 19th. The present paper is one of the first attempts to study the genetic aspects of high-mountain Technosols in the temperate climatic zone. The study involved determining soil morphology and classification, soil properties, magnetic susceptibility, mineral composition, optical microscopic observations and total concentration of major elements. The studied Technosols were poorly developed soils with simple soil morphology (mainly A horizon in the topsoil and C horizons in the subsoil). There was a high content of rock fragments. The research has shown that the properties of Technosols in the Tatra Mountains were primarily determined by past human activities like mining and metallurgy as well as the type of anthropogenic parent material, which included mining wastes and metallurgical slags and determined soil properties together with mineral and chemical composition. Soil formation was significantly influenced by vegetation which was conditioned by the relief and climatic conditions dependent on altitudinal zonation. Vegetation and plant-derived soil organic matter shaped topsoil properties. The lengthy soil-forming process acting since a few centuries in some Technosols led to the formation of Bw horizons.

Desert landscape features influencing the microgeographic genetic structure of Nelson's pocket mouse Chaetodipus nelsoni.

Elucidating the factors that drive the genetic patterns of natural populations is key in evolutionary biology, ecology and conservation. Hence, it is crucial to understand the role that environmental features play in species genetic diversity and structure. Landscape genetics measures functional connectivity and evaluates the effects of landscape composition, configuration, and heterogeneity on microevolutionary processes. Deserts constitute one of the world's most widespread biomes and exhibit a striking heterogeneity of microhabitats, yet few landscape genetics studies have been performed with rodents in deserts. We evaluated the relationship between landscape and functional connectivity, at a microgeographic scale, of the Nelson's pocket mouse Chaetodipus nelsoni in the Mapimí Biosphere Reserve (Chihuahuan desert). We used single-nucleotide polymorphisms and characterized the landscape based on on-site environmental data and from Landsat satellite images. We identified two distinct genetic clusters shaped by elevation, vegetation and soil. High elevation group showed higher connectivity in the elevated zones (1250-1350 m), with scarce vegetation and predominantly rocky soils; whereas that of Low elevation group was at <1200 m, with denser vegetation and sandy soils. These genetic patterns are likely associated with the species' locomotion type, feeding strategy and building of burrows. Interestingly, we also identified morphological differences, where hind foot size was significantly smaller in individuals from High elevation compared to Low elevation, suggesting the possibility of ecomorphs associated with habitat differences and potential local adaptation processes, which should be explored further. These findings improve our understanding of the genetics and ecology of C. nelsoni and other desert rodents.

Atlantic Forest Regeneration Dynamics Following Human Disturbance Cessation in Brazil

The Brazilian Atlantic Forest (BAF) is one of the most important biodiversity hotspots and species-rich ecosystems globally. Due to human activities, it has been significantly reduced and fragmented. This study examined both biotic (floristic composition, diversity, and structure) and abiotic (topographic and soil) factors in BAF fragments undergoing varying levels and durations of human disturbance cessation: approximately 20 years (20 y), ~30 years (30 y), and over 40 years (&gt;40 y). We aimed to understand the recovery dynamics of floristic composition, diversity, and structure in BAF fragments in relation to abiotic factors. Several statistical tools were employed to examine similarities/differences and relationships. Forests of the 30 y group exhibit significantly greater homogeneity in terms of floristic composition, while forests of the 20 y group are characterized by lower species abundance and diversity. The floristic composition was primarily influenced by soil features and the time of disturbance. Under “Environmental Protection Areas”, soil–vegetation recovery can occur more swiftly than usually observed for BAF. A significant BAF recovery was observed approximately 40 years after the end of human disturbance. A partial recovery featured 30 y disturbed areas, while in 20 y forests, recovery is in its early stages. Human-disturbed BAF can gradually rebound when effective management practices are implemented.

Protection of understory vegetation by deer exclosure fences prevent the reduction of beech growth due to soil erosion

Overbrowsing by ungulates has degraded understory vegetation in worldwide forests. Understory degradation causes soil erosion and environmental degradation, causing mature tree decline. Although ungulate exclosure fences are installed to protect vegetation, their effectiveness in preventing tree decline associated with soil degradation remains unclear. We aimed to fill this gap on slopes of Mt. Shiraga, Japan, where sika deer have overbrowsed for >20 years. Tree-ring records in 1960–2022 for eight beeches per each of inside and outside fences were analyzed to compare stem basal area increment (BAI, cm−2 yr−1) and trend change timings for BAI (i.e., break-point). Soil properties, exposed root height (ERH) as cumulative soil erosion index, and intrinsic water use efficiency (iWUE) as water limitation proxy were also compared. Compared with areas inside fences, areas outside fences had no understory vegetation, higher ERH, and higher soil hardness and moisture. BAI outside fences turned their growth trend from positive to negative since 2004, but not inside fences. Break-point of BAI outside fences matched the understory degradation period in the field. The long-term BAI trend (i.e., regression slope of BAI) after the break-point was negatively related to ERH but not to soil properties (e.g., soil hardness and moisture). Furthermore, BAI outside fences was negatively related to iWUE after the break-point, whereas BAI inside fences was not. These results indicate that the maintenance of understory by fencing prevents overbrowsing-associated mature tree decline through mitigating root exposure and related water limitation, despite the potential of water competition with understory.

Assessing the Soil Infiltration Rate of Alpine Meadows Using the Electrolyte Tracer Method

ABSTRACTGrassland on the Qinghai‐Tibet Plateau is highly susceptible to climate change and human activities, and vegetation degradation can affect biodiversity and soil erosion. Soil infiltration is a crucial water flow process that determines the amount of runoff and water storage capacity, and it is of great importance in maintaining biodiversity. This research investigated the effects of vegetation degradation and soil rates on soil infiltration rate and processes using the electrolyte tracer method. This technique accurately calculated soil infiltration rate by tracking continuous changes in the solute concentration change process throughout the experimental period and did not require calibration. Findings indicate that vegetation type, root mass, soil water content and soil porosity significantly affect soil infiltration rate. In particular, root mass was found to have a negative effect on soil infiltration rate. Soil moisture content initially dominated soil infiltration, but subsequently, soil porosity became increasingly influential in affecting infiltration in degraded meadow. Soil infiltration capacity varied more with vegetation type than with surface runoff. Shrub meadows had the highest infiltration rate followed by normal alpine meadows and degraded meadows, indicating the importance of vegetation on soil infiltration. The research also shows that mixed shrub and meadow can improve the ecological environment by introducing a more complex root system and increasing the infiltration rate. The electrolyte tracer method was used as an alternative to other methods that can be used in different environments than the one studied in this research.

Spatiotemporal Changes in Vegetation Cover and Soil Moisture in the Lower Reaches of the Heihe River Under Climate Change

As global climate change intensifies, arid land ecosystems face increasing challenges. Vegetation, a key indicator of climate variation, is highly responsive to meteorological factors such as temperature (Tem), precipitation (Pre), and soil moisture (SM). Understanding how fractional vegetation cover (FVC) responds to climate change in arid regions is critical for mitigating its impacts. This study utilizes MOD13Q1-NDVI data from 2000 to 2022, alongside corresponding Tem, Pre, and SM data, to explore the dynamics and underlying mechanisms of SM and FVC in the context of climate change. The results reveal that both climate change and human activities exacerbate vegetation degradation, underscoring its vulnerability. A strong correlation between FVC and both Tem and Pre suggests that these factors significantly influence FVC variability. In conclusion, FVC in the lower reaches of the Heihe River is shaped by a complex interplay of Tem, Pre, SM, and human activities. The findings provide a scientific basis and decision-making support for ecological conservation and water resource management in the lower reaches of the Heihe River, aiding in the development of more effective strategies to address future climate challenges.

Grass species and mycorrhizal fungi improved aggregate stability of compacted and vegetated soils

Abstract Aim Compaction of slope soils can substantially hinder root penetration of grass cover, which may be alleviated through the colonisation of arbuscular mycorrhizal (AM) fungi and aggregate stabilisation. We investigated aggregate stabilisation and breakdown mechanisms in compacted dense mycorrhizal soils. Methods A pot-culture experiment with seven treatments (five replicates per treatment) was implemented. In a local decomposed granitic soil, we inoculated two grass species (Chrysopogon ziaanioides and Cynodon dactylon) with AM fungi. We used loose soil to grow C. dactylon to compare it with compacted dense soil, as well as pots without a plant and/or fungal inoculation for comparison. After 20 weeks of cultivation, we measured root and AM fungal characteristics, soil organic matter and aggregate properties by dry sieving, wet sieving and Le Bissonnais methods. Results Compaction led to the formation of macro-aggregates (&gt; 0.25 mm) but had a negative influence on the aggregate stability. The fungal inoculation increased polysaccharide production and aggregate stability in the compacted soil vegetated with C. dactylon. The inoculated C. ziaanioides showed a similar level of aggregate stability as the inoculated C. dactylon, but the uninoculated group demonstrated higher aggregate stability compared with the inoculated group owing to root decomposition. The aggregate stability against various breakdown mechanisms was related to the established aggregate hierarchy and qualitative organic matter inputs. Conclusion Soil organic matter supplied by grass species together with the mediation of AM fungal hyphae played a crucial role in the systemic enhancement of aggregate stability in the compacted soil.

Agricultural drought monitoring and early warning at the regional scale using a remote sensing-based combined index.

Early detection of agricultural drought can alert farmers and authorities, enhancing the resilience of the food sector. A framework is proposed for developing a novel regional agricultural drought index (RegCDI) by combining remotely sensed vegetation health, soil moisture and crop water stress via a transparent Shannon's entropy weighting method. The framework consists of the selection of suitable datasets based on their regional performance, the aggregation of selected drought indicators, the validation of the combined index against crop yield, and the testing of predictive capabilities. The creation and performance of RegCDI are demonstrated for the drought prone Indian state of Odisha. MODIS surface reflectance is selected for crop water stress and GLDAS-2 for assessing soil moisture deficits and vegetation health. Three selected indicators (SMCI, TCI, and SIWSI-1) are combined into RegCDI for Odisha. The performance of RegCDI is evaluated (a) against other popular drought indices and (b) by comparing with seasonal crop yields. RegCDI is used to identify drought hotspots based on drought severity, duration, and propensity over the study area. A reforecast evaluation of RegCDI (up to three months ahead) showed that the indicators based on soil moisture deficit and crop water stress could predict drought conditions up to two months ahead with no less than 80% accuracy. This demonstrated the potential of the RegCDI framework and its component indicators for early warning of drought in Odisha.

Spatiotemporal Variability of Soil Erosion in the Pisha Sandstone Region: Influences of Precipitation and Vegetation

The Pisha sandstone area, situated in the upper and middle reaches of the Yellow River in China, is characterized by severe soil and water erosion, making it one of the most critical regions on the Loess Plateau. The rugged terrain and exposed bedrock complicate management efforts for this area, posing challenges for accurate forecasting using soil erosion models. Through an analysis of terrain, vegetation, and precipitation impacts on soil erosion, this study offers theoretical support for predicting soil erosion within the exposed Pisha sandstone area of the Loess Plateau. This has substantial implications for guiding water and soil conservation measures in this region. Focusing on China’s exposed sandstone area within the Geqiugou watershed, temporal and spatial changes in vegetation cover and land use from 1990 to 2020 were analyzed. The result shows that, from 1990 to 2020, the grassland area has exhibited a consistent downward trend, with successive reductions of 64.86% to 59.46%. The area of low vegetation cover witnessed a significant decline of 59.29% in 2020 compared to that in 1990. The moderate erosion area decreased from 84.52 to 57.17 km2. The significant reduction in soil and water loss can be attributed to the expansion of forest and grassland areas, with the implementation of the Grain for Green project serving as a key policy driver for facilitating this expansion. This study provided a good example of combining rainfall with vegetation coverage to fast estimation soil erosion. A mathematical relationship between the vegetation rainfall coupling index (RV) and soil erosion was established with strong fitting effects, enabling estimation of the soil erosion volume under varying slope conditions within Pisha sandstone areas. The main focus of future soil and water conservation in the Pisha sandstone area should be on effectively managing the channel slope and minimizing exposed bedrock areas through a combination of slope cutting, the application of anticorrosive materials, and the implementation of artificial vegetation planting.

Developing Site-Specific Prescription Maps for Sugarcane Weed Control Using High-Spatial-Resolution Images and Light Detection and Ranging (LiDAR)

Sugarcane is a perennial grass species mainly for sugar production and one of the significant crops in Costa Rica, where ideal growing conditions support its cultivation. Weed control is a critical aspect of sugarcane farming, traditionally managed through preventive or corrective mechanical and chemical methods. However, these methods can be time-consuming and costly. This study aimed to develop site-specific, variable rate prescription maps for weed control using remote sensing. High-spatial-resolution images (5 cm) and Light Detection And Ranging (LiDAR) were acquired using a Micasense Rededge-P camera and a DJI L1 sensor mounted on a drone. Precise locations of weeds were collected for calibration and validation. Normalized Difference Vegetation Index derived from multispectral images separated vegetation coverage and soil. A deep learning (DL) algorithm further classified vegetation coverage into sugarcane and weeds. The DL model performed well without overfitting. The classification accuracy was 87% compared to validation samples. The density and average heights of weed patches were extracted from the canopy height model (LiDAR). They were used to derive site-specific prescription maps for weed control. This efficient and precise alternative to traditional methods could optimize weed control, reduce herbicide usage and provide more profitable yield.