Litter Density Research Articles

Study of pollution status in urban environment caused by attitude and waste littering behavior of citizens

Littering behavior is one of the main challenges in waste management, especially in big cities. In this study, density and composition of litter in Tehran was investigated and the urban pollution status was calculated by using the clean environment index. The results showed that the average density of litter in the studied locations was 0.182 number/m2. Spatial variation in the litter density showed that the average density in commercial and residential land-uses was 0.22 and 0.14 number/m2, respectively. Cigarette butts (29%), bottle caps (18%), and paper receipts (10%) consisted the largest ratio of the litter composition in the studied locations. Clean environment index for the studied locations was calculated in the range of 2.34 to 10.42. Based on this, 30% of the studied locations were in a clean status and 70% were in a polluted and worse status. The litter density in the city, interviews with citizens, and the results of previous studies showed insufficient awareness of citizens about the consequences of littering in the urban environment, which led to the prevalence of littering behavior. So, the littering behavior by citizens has caused the urban environment pollution and increased health risk. Educating citizens and modifying their behavior to avoid littering is necessary to improve the observed status.

Litter in French urban areas-part 1: composition, sources, and spatio-temporal variations on urban surfaces.

Urban areas concentrate on human activities that generate large amounts of waste. A small fraction is mismanaged and ends up on urban surfaces and eventually in waterways. The fraction reaching waterways is usually estimated using poorly constrained data, while litter density on urban surfaces and its subsequent transfer dynamics are also poorly documented. This study provides new insights into litter composition, sources, and spatio-temporal variations in the urban catchments of Pin Sec and Jules Verne (Nantes, France), which are dominated by industrial/commercial, collective, and individual housing areas. Regular litter collection on selected street sections was combined with visual counting of street litter (> 1 cm). In total, 50.8 kg (dry weight) of litter were collected and 232,217 items were counted, mainly smoking and food consumption-related items. Litter densities ranged between 40,000 and 452,000 items/km2 depending on local activities, item mobility, and land use as a driver of road and foot traffic. A median litter accumulation rate of 7 g/inhabitant/day was estimated, suggesting that 0.6% of the total amount of waste generated in public places is mismanaged. Results over space show that litter is strongly correlated with land use and that litter accumulation is promoted in green spaces. Results over time show that litter stock is quickly renewed and that items may have long residence time on urban surfaces.

Seasonal difference in marine litter along the coast of Dar es Salaam, Tanzania

Marine litter accumulation poses a significant threat to marine ecosystems and biodiversity. Marine litter and the influence of river discharge on marine litter accumulation during wet and dry seasons along the coast of Dar es Salaam was investigated. Litter samples collected between 2019 and 2021 from transects on beaches and by nets spanned across two rivers were counted, dried and weighed, and litter counts and weight (kg) calculated by area (litter/m2) and volume (litter/m3). Over three years, a total of 127,658 marine litter items weighing 470 kg were sampled from beaches, and 1,365 items from rivers, in nine different litter categories. Most of the litter (70 %) was produced locally and the marine litter density decreased by 61 % over the three years of the study. Litter densities at beaches and rivers were significantly greater during the wet than the dry season, attributed to the transport of litter in rivers to the ocean, especially plastics, which had a higher density than other riverine litter. It is concluded that high local plastic pro- duction and poor waste disposal systems require an intervention, and that a policy to minimize and reduce marine litter should be developed and implemented.

Effects of the types and ages of vegetation restoration on land surface roughness in the Eastern Hobq Desert, Northern China

Vegetation restoration has an important remodelling effect on near-surface characteristics, and consequent changes in land surface roughness (LSR) are key influences on soil wind erosion processes. However, the effects of vegetation restoration types and ages on LSR and the underlying mechanisms are not fully understood. In this study, the sand-fixing vegetation restoration area of the Hobq Desert was examined in comparison to a bare sand control area. The LSR of four artificial vegetation types (Salix psammophila, Caragana korshinskii, Artemisia ordosica, and Populus simonii) with restoration age of 36 years, and Salix psammophila and Caragana korshinskii after different periods of restoration (20, 28, 36 and 45 years) were measured using Structure-from-Motion (SfM) photogrammetry. Near-surface characteristics that may affect LSR were also measured. The results showed that vegetation restoration was associated with a 230–409 % higher LSR compared to the control site (1.74 mm). LSR in the different vegetation restoration areas were ranked, from high to low, as follows: AO (8.85 mm) > CK (7.89 mm) > SP (6.70 mm) > PS (6.61 mm). LSR also increased with time since restoration, with the greatest rate of increase during the first 20 years. The change of LSR is mainly affected by the change of near-surface characteristics, with the direct effects of biological crust thickness (0.331), litter thickness (0.289), soil bulk density (−0.239), and clay content (0.171) being significant. Stem diameter, litter density, biological crust coverage, and soil organic matter affected LSR indirectly, mainly through acting on the above factors. Finally, LSR was effectively estimated based on biological crust thickness, litter thickness, and soil bulk density (R2 = 0.904). The research results will help to further deepen the understanding of the influence mechanism of vegetation restoration on LSR, and provide scientific basis and practical reference for vegetation ecological restoration in similar areas.

Decoupling the effects of near-surface characteristic change on soil roughness in a dune-meadow cascade ecosystem

As an important indicator of ecological restoration, soil roughness changes exhibit a synergistic evolutionary relationship with near-surface characteristics such as soil and vegetation. However, the main controlling factors for changes in soil roughness in different ecosystems are still unclear. This study was conducted to clarify the changes in soil roughness in different ecosystems and to decouple and quantify the impact of near-surface characteristics on soil roughness in the Horqin Sandy Land (China). Soil roughness was measured using the structure-from-motion (SfM) technique, showing a pattern of farmland (14.08 mm) > semi-mobile dune (12.59 mm) > meadow (6.19 mm) > woodland (5.67 mm). Redundancy analysis (RDA) results showed that the near-surface characteristics of the dune-meadow cascade ecosystem that explained soil roughness, in descending order of importance, were as follows: sand, soil moisture content (MC), silt, plant stem diameter (SD), clay, pH, soil organic matter (SOM), soil shear resistance (SC), litter thickness (LT), water-stable aggregates (WSA), litter density (LD) and bulk density (BD). Specifically, in the semi-mobile dune ecosystem, the order of total effects on soil roughness was as follows: sand (1.311) > pH (0.447) > clay (0.387). In the woodland ecosystem, SC (0.226), pH (|-0.216|), and LD (0.179) were important factors controlling soil roughness. In the farmland ecosystem, MC (0.380), LT (|-0.378|), and SOM (|-0.336|) were the main controlling factors of soil roughness. In the meadow ecosystem, silt (0.574), SOM (|-0.413|), and clay (|-0.380|) significantly influenced soil roughness. Compared to other machine learning models and stepwise regression models, the k-nearest neighbors (KNN) model could predict soil roughness changes more accurately. The findings of this research are of great significance for ecological restoration and sustainable development of the ecologically fragile areas in northern China.

Production and decomposition of mangrove litter in Dompak estuary waters, Tanjungpinang

Levels of density, production and decomposition of litter in Dompak Estuary Waters. The aim of this research is to determine the level of density, production and decomposition of Mangrove litter in the Dompak Estuary Waters of Tanjungpinang City. This research was carried out in February - March 2024. In determining the sampling points the researchers used the Purposive Sampling method. Sampling in this research used the line transect method. The results of the research show that the level of mangrove density at station 1 is 1,299 ind/ha in the medium category, station 2 is 599 ind/ha in the rare category and station 3 is 1,666 ind/ha in the dense category. Mangrove cover at station 1. Amounted to 73.83% with medium criteria in the medium category. Station 2. Amounting to 65.60% with medium criteria in the medium category and station 3 amounting to 79.93 with solid criteria in the good category and the production of mangrove litter in Dompak Estuary Waters is 3.09 gbk/m2. With a leaf composition of 7.10 gbk/m2, twigs of 0.48 gbk/m2 and flowers/leaves of 1.69 gbk/m2. Mangrove decomposition at station 1 was 21.74%, station 2 was 29.88% and station 3 was 21.14%.

Baseline assessment of macrolitter on the coastline of Algeria: Fit-for-purpose data for tailor-made measures to navigate the Plasticene Age

Curbing the growing threat of marine litter requires reliable, coherent and fit-for-purpose data. The present study reports the findings of beach macrolitter surveys carried out in seventeen sites along the coastline of Algeria. The median litter density recorded along these sites amounted to 578 items per 100 m of coastline (range: 317–2684 items/100 m). Every surveyed beach exceeded the European threshold value of 20 items per 100 m of coastline by a significant margin. In addition, the evaluation conducted employing the Mediterranean threshold value of 130 items per 100 m of coastline indicated that each of the seventeen surveyed beaches resides within the non-Good Environmental Status spectrum. A significant proportion of the litter, accounting for 43 %, is attributed to food and beverage consumption-related items, highlighting the impact of single-use food packaging, including food and beverage containers resulting from unsustainable practices mainly by beach users and inadequate waste management.

Study of the impact of structural factors and cleaning efficiency in reducing hazardous litter density and its related pollution in urban environment

Cigarette filter is the most common hazardous litter that contains many pollutants including PAHs. The durability of this litter in the urban environment has an important effect on the rate of pollutant leakage. In this study, the leakage rate of PAHs from the littered cigarette filters was estimated by considering the affecting parameters on their durability in the urban environment. The results showed that the density of littered cigarette filters in the studied locations was 0.00048–0.13563 g/m2. The maximum spatial variation of the littered cigarette filter was 225 times. The average leakage of the total studied PAHs was estimated to be 2.048 µg/10 m2. The impact of structural factors and efficiency of urban cleaning in the estimated leakage was at most 2.4 times. It is necessary to change the behavior of citizens in littering the cigarette filter, considering its durability in the urban environment, to reduce the environmental and health consequences caused by the leakage of PAHs.

Litter in French urban areas-Part 2: transport dynamic and fluxes in stormwater.

Urban areas constitute a major hotspot of litter, including plastic litter, that stormwater can wash off towards waterways. However, few studies quantified and characterized litter densities in urban areas and fluxes transported by stormwater networks. Moreover, little information is available on litter transport dynamics in stormwater, and on the factors driving this transport. This study aims at characterizing and quantifying litter amounts transported by stormwater of two nested French urban catchments (total surface area of 105ha). Litter densities relative to land uses and rain events were investigated in the same catchments as in a compagnon paper (Ledieu et al., 2024). The present study explores the impact of rain events on the transport of urban litter in stormwater. Litter collection and characterization combined with a capture/recapture experiment using tagged litter placed in stormwater inlets show total litter fluxes of 29kg/year, in which 14kg/year are plastics, exported at the stormwater outlet. These fluxes confirm that stormwater runoff is a considerable pathway from urban surfaces to waterways, especially regarding small plastic litter (< 2.5cm). Item transport dynamic is however not linear and only 0.3% of the urban litter appear remobilized. Litter transport dynamics depends on several factors (urban litter densities, hydrometeorological parameters, item composition and morphologies, and stormwater management systems) that should be considered in global models.

Plastic litter assessment of the riverbanks of Pulot River and its tributary in Sofronio Española, Palawan Island, Philippines

Rivers are essential sources of plastic litter in the marine environment. Recently, the Philippines was reported as the biggest polluter of plastic litter from riverine sources. However, the riverine plastic litter's origin has been less established. In this study, we determined the density, composition, and accumulation of plastic litter on the riversides of Pulot River and its tributary in Palawan Island, Philippines. We also identified the possible sources of plastic litter. Results showed that the plastic litter density was highest at the river edge during the first sampling period. Litter densities for the predefined zones and sampling periods all showed no significant differences. The most dominant plastic litter types were food packaging and plastic bags, followed by toiletries. ‘Others’ consisted of multilayers, mixed, and plastics accounted for the most abundant polymer types. We identified the residents in the vicinity illegally dumping litter, for there were small illegal dumping sites along the river. These results suggest the urgent need for better waste policy implementation measures to protect the riparian environments and reduce the input of riverine plastic litter into the marine environment to ensure river resource sustainability.

Effect of manual cleaning system on urban pollution and litter management in developing areas

Litter is an important challenge in urban management, which is affected by the efficiency of the cleaning system. In this study, the efficiency of manual cleaning system in litter collection was evaluated by Clean Environment Index (CEI) in three land-uses. The results showed that in the study area, the density of litter was in the range of 0.011–0.736 number/m2. The cigarette butt was the most observed litter (0.183/m2). On average, 17% of the observed litter were plastic. Based on calculated CEI, all commercial areas were in a dirty or extremely dirty status, which included 40% of all areas. However, residential and recreational areas were in clean and very clean status, respectively. The average CEI in commercial, residential, and recreational areas was 22.59, 3.69, and 0.413, respectively. Although the efficiency of manual cleaning was suitable for residential and recreational areas, the pollution status in commercial areas showed the low efficiency of the manual cleaning system. Using alternative methods for commercial areas can improve the litter management.

Plastic pollution on Moroccan beaches: Toward baselines for large-scale assessment

In Africa, Morocco is the 10th largest producer of plastic. The severity of this plastic has attracted increasing amounts of attention in the Moroccan Atlantic and Mediterranean in recent years. However, at the national level, there is limited knowledge of plastic pollution. To obtain an exhaustive and comprehensive evaluation of plastic pollution levels in Morocco, large-scale monitoring is needed on all the coasts of the country. In this context, this paper examined the composition, abundance, distribution, source and quality of beaches on two Moroccan coasts using four beach quality indices along 29 beaches. During two seasons, a total of 72,105 items were counted. The mean litter abundance was 0.31 items/m2, and the Mediterranean beaches were more dense than the Atlantic beaches. In particular, litter density was greater in spring (0.35 items/m2) than in summer (0.29 items/m2). The data indicate considerable differences in the density of marine debris according to the seasonality, beach typology and presence of rivers. Hazardous litter items were collected along both Moroccan coasts, constituting 8.41 % of the total collected items, with a mean of 0.026 items/m2. The use of environmental indices allowed us to classify Moroccan beaches as “moderate cleanliness”, “moderate abundance” of plastics, “moderately safe” presence of hazardous litter and “mediocre” environmental status. The findings of the present study indicate that the sources of litter on both Moroccan coasts come mainly from recreational activities and dumping. The waste management practices recommended for Moroccan beaches include reducing sources, mitigating mitigation measures and changing littering behavior.

The impact of different management on pine-based agroforestry system and litter accumulation on the population and activity of cellulolytic bacteria

Abstract. Arfarita N, Nuraini Y, Rinady MVP, Noerhayati E, Prayogo C. 2024. The impact of different management on pine-based agroforestry system and litter accumulation on the population and activity of cellulolytic bacteria. Biodiversitas 25: 924-936. Agroforestry leads to the accumulation of organic matter, and the environmental conditions, litter quality, and decomposing organisms influence the rate at which litter decomposes. Litter decomposition in agroforestry systems is slow due to the high lignin and phenolic substances content, low light intensity, and high humidity under the canopy's shading condition. Therefore, a study was carried out to address this issue to isolate cellulolytic bacteria capable of breaking down plant litter using a qualitative cellulase activity testing method. The complete randomized block design and Tukey's test were used to determine the treatment's significance. Six agroforestry systems were examined: pine-coffee, pine-banana, pine-cardamom, pine-cardamom, mixed garden, and citrus. The PK (Pine-Coffee) plot had the highest canopy cover, litter density, and cellulolytic bacteria. The study identified three cellulolytic bacteria isolates (PK1, PK13, and PK10) from the 50 isolated bacteria of PK plot, producing the largest clear zones on CMC media. These identified isolates belonging to the Bacillus genus were Gram-positive bacteria with rod-shaped cells. The different types of litter in agroforestry systems affect the content of lignin, polyphenols, cellulose, and C/N ratios, which can influence the abundance of cellulolytic bacteria and their potential cellulase activity.

Assessment of seabed litter at Concepción Seamount (Canary island) using a remotely operated towed vehicle

The seafloor is recognised as a major sink for marine litter. However, studies conducted in this compartment addressing marine litter densities and its interactions with fauna are scarce, mainly due to sampling constraints. In this paper, we assess marine litter density, composition and interactions with marine communities and evaluate its relationship with fishing activities at the “Banco de la Concepción” seamount (Canary Islands, Spain). We took advantage of underwater video records taken with a Remotely Operated Towed Vehicle in the framework of the LIFE IP INTEMARES project.A total of 56 video transects were analysed covering about 9 km with 19 h of video recording. Transects were categorised as high, low, and null fishing effort based on the Vessel Monitoring System (VMS) positional data registered between 2009 and 2017. Litter items were recorded in 70% of the transects with a mean density of 2122 (±2464) items km−2. There were significant differences in litter densities over the three levels of fishing pressure, with a density decrease from stations of high to stations of null fishing pressure.Regarding categories, plastic was by far the most abundant category found (83.1%), mainly consisting of fishing lines, both monofilaments and entangled longlines. The study of the interactions of marine litter with fauna showed that less than 20% of the items presented an interaction with benthic organisms either by causing or not a visible impact. The sponge Asconema setubalense accounted for more than half (57.4%) of all interactions, but only 5% of all A. setubalense specimens showed physical damage.

The first assessment of marine litter on Somalian coast: The case of Liido Beach, Mogadishu

This paper presents the first assessment of marine litter in the Mogadishu coastal area of Somalia. Samples were collected monthly using 100 m × 40 m transect and classified following OSPAR Marine Litter Survey Guide while litter sources were identified using Ocean Conservancy Marine Debris Index. The results showed a total of 119873 items consisting of plastics (89.47%), clothing items (7.53%), and others (3.00%) recovered from Liido Beach. Litter density ranged from 2.19 items/m2 to 14.18 items/m2 with a mean of 6.25 items/m2 and Clean Coast Index (CCI) suggesting that Liido Beach is extremely dirty (>20 items/m2). In addition, the primary sources of marine litter at the beach are local recreational and shoreline activities (54.12%), and dumping (36.61%). The dominance of plastic litter on the beach poses potential threats to marine biodiversity in the Somalia coastal area and the West Indian Ocean. It is recommended that effective strategies and solutions to mitigate litter on the beach and other coastal areas in Somalia should be developed and compensated with public education and awareness campaigns across the country.

High levels of anthropogenic litter trapped in a mangrove area under the influence of different uses

The contamination of mangroves by anthropogenic litter has increased in recent decades. Notably, Brazil occupies a prominent status within Latin America, boasting the second-largest mangrove areas globally. In Santos-São Vicente Estuarine System (SESS), mangroves coexist with a preeminent port complex and substantial urbanization rates. Nevertheless, the anthropogenic litter occurrence and distribution in this ecosystem remains unknown. This study aimed to comprehensively assess anthropogenic litter across 13 strategically positioned sites in the SESS. The total litter density (Mean ± SD) was 22.84 ± 36.47 (0.00–142.00) items·m−2, putting the SESS among the top four most contaminated mangrove ecosystems worldwide. Residential zones accumulated more litter than uninhabited areas and significant correlation was seen with human modification index. Plastic was the prevalent material (70.4 %), measuring mostly between 2.5 and 30 cm (41.1 %). It is imperative that local authorities adopt comprehensive strategies to mitigate contamination, while also curtailing the litter inputs to the SSES mangrove ecosystem.

Wildfires’ Effect on Soil Properties and Bacterial Biodiversity of Postpyrogenic Histic Podzols (Middle Taiga, Komi Republic)

Data on the main properties of Histic Podzols in the pine forests of semi-hydromorphic landscapes in the middle taiga of the Komi Republic after forest fires are presented. A decrease in topsoil horizon thickness by more than 7.6 times, an increase in litter density by 6 times, and a decrease in litter stock by 4 times were observed in postfire soil. There was an increase in carbon content in the pyrogenic horizon (48%) and in the upper part of the podzolic horizon—from 0.49 at the control plot to 1.16% after the fire. The accumulation of all studied trace metals (Cu—from 2.5 to 6.8 mg × kg−1; Zn—from 35.7 to 127.4 mg × kg−1; Ni—from 2.2 to 8.1 mg × kg−1; Pb—from 1.4 to 28.3 mg × kg−1; Cd—from 0.3 to 1.1 mg × kg−1) in soils after wildfires was recorded. The effect of the fire can be traced to a depth of approximately 20–30 cm. A significant influence of the pyrogenic factor on the alpha and beta bacterial diversity was noted. The bacterial response to a forest fire can be divided into an increased proportion of spore-forming and Gram-negative species with complex metabolism as well.

Abundance and transport of macro-litter at sea turtle nesting beach: A case study for sustainable habitat management

In the last few decades, the worldwide production and usage of plastic have increased substantially. As a consequence, a major proportion of the mismanaged plastic is leaking from the land (source) to the sea (sink) affecting the marine environment in the form of emerging contaminants. Along the east coast of India, the sandy beaches adjacent to River Rushikulya support the winter mass nesting of Olive Ridley Sea turtles. The present study assesses the beach litter density (items/m2), composition (%), probable sources, and transport pathway prior to the nesting event. Sampling was carried out at four transects covering a 400 m2 area during low tide, aggregates to 890 litter materials of 15 categories. The Clean Coast Index (CCI) shows the maximum density (moderately clean to dirty) of litter observed along the backshore and the minimum (very clean) on the foreshore. The particle tracking model carried out for two seasons i.e., southwest and northeast monsoon infers that the transporting time of the litter from river to beach varied between 3–4 and 6–7 days, respectively. Our study suggests most of the debris accumulated on the nesting beaches after the monsoonal flood. Thus, it is recommended that cleaning the beaches by engaging local fishermen prior to the nesting, installing trash booms, and managing solid wastes in the river upstream, are some of the doable, effective, and best management practices that need to be adopted for sustainable management of this turtle rookery habitat.

A baseline assessment of anthropogenic macrolitter on dunes along the Bulgarian Black Sea Coast using visual census and Unmanned Aerial Systems

Beach-dune systems are among the most dynamic and sensitive elements of coastal ecosystems in the world. They represent an intersection between human activities, flora, fauna and economic interests in tourism. The Bulgarian Black Sea shoreline spans 518.7 km and comprises 131 km (25%) of the depositional coast, including beaches and 46 dune systems. Over the past three decades, heavy anthropogenic impacts have been observed, significantly altering the cleanliness of the beach-dune systems along the Bulgarian Black Sea Coast (BBSC). The research initially began as an initial assessment of macrolitter on dunes (MLD) using Unmanned Aerial Systems (UAS). However, due to concerning data obtained in the first year, it transitioned into a mid-term monitoring program conducted between 2018 and 2022. The baseline assessment is based on a visual census, UAS mapping and manual image screening procedure in a GIS environment for litter mapping in 40 areas of litter monitoring (ALMs) along the Bulgarian Coast. Throughout the five-year monitoring period, the most abundant type of MLD was “Artificial polymer materials,” accounting for 83.4% of the total number, followed by “Paper/Cardboard” (6.2%), “Glass/Ceramics” (2.8%), “Metal” (2.8%), “Processed/Worked wood” (1.83%), “Rubber” (1.29%), and “Cloth/Textile” (1.17%). Generally, 95% of the total litter amount was assessed from Land-based sources and 5% from Sea-based sources. The COVID-19 pandemic indirectly affected the cleanliness of the Bulgarian dunes due to restrictions on foreign travel, which increased the domestic tourist pressure on the Bulgarian beaches, resulting in a more significant amount of waste accumulating on the beaches and dunes. The abundance experienced an increase of 39% between 2018 and 2021. A similar upward trend (+41%) was observed in the density of macrolitter on the dunes. Based on visual census data, the average density was estimated to be 0.54 ± 0.35 items/m2. The spatial distribution of MLD is a complex combination of anthropogenic impact and wind processes that affect various eco-geomorphological elements of the beach-dune system. The embryonic dunes retained only 16% of the total items (Dav: 0.32 ± 0.12 items/m2). The highest litter density was registered on the foredunes (Dav: 0.71 ± 0.21 items/m2; 28% of total items). The backdunes contained the highest litter abundance, accounting for 55% in larger areas (Dav:0.59 items/m2). Density litter maps established that dune vegetation acted as a natural trap, retaining 40% more macrolitter compared to areas without dune plants. A Clean Dune Index (CDI) was developed to evaluate the cleanliness of Bulgarian dunes. Based on aggregated CDI data for 2018–2022, the cleanliness of the dunes along the Bulgarian Coast was categorised as “moderate” (CDIav:10.89). Dune systems near the most visited resorts were classified as “extremely dirty”, with the highest CDI values recorded at Kavatsite (27.22), Nessebar – South (25.01), Bolata (24.69), Asparuhovo - Varna (24.33) and Slanchev bryag (24.09). On the other hand, the dune systems at Ropotamo and Lipite were rated with the lowest CDI – 0.95 and 1.2. Dunes are sensitive habitats and require minimal anthropogenic impact, which requires the intensification of the use of high-resolution remote sensing methods for litter mapping. The quality of the presented data and the results obtained outline drones as a future primary tool for beach and dune surveys.

Water-holding characteristics of litter and soil and the influencing factors after individual rainfall

To clarify the water-holding characteristics of forest litter and soil, different densities (0, 300, 600, 900 g·m-2) of Pinus tabuliformis litter were covered on the typical soil surface of loess cinnamon and calcareous cinnamon in north China. Based on an artificial simulated rainfall experiment, we observed the variation of litter and soil water content with time, and analyzed the variation process and influencing factors of litter and soil water content after rainfall. The results showed that water content of P. tabuliformis litter decreased significantly with the increases of duration after the rainfall, and that the range of litter water contents under all treatments was 22.9%-71.0%. There was a decreasing exponential function between the decline rate and time. Litter water content was only affected by litter density. The higher the litter density, the greater the decreasing rate of litter water content. Soil water content fluctuated and decreased with the increases of duration after the rainfall, with a variation of 1.5%-8.5%. Soil water-holding capacity was affected by litter density, soil type, and slope position. Litter could effectively reduce the fluctuation of soil water. The higher litter density, the smaller the coefficient of variation of soil water content, the greater the effect of litter on soil water fluctuation, and the better the soil water-holding capacity. The water-holding capacity on loess cinnamon soil was significantly higher than that of calcareous cinnamon soil. Soil water-holding capacity on the downslope was significantly higher than that on the upslope and middle slope, without any difference between upslope and middle slope.